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With the anticipated population growth by 2050, the demand for high-quality protein for human consumption is set to rise. To enhance the sustainability of U.S. cattle production, producers and researchers have traditionally concentrated on improving the feed efficiency of steers through advancements in genetics, nutrition, and microbiome tools, resulting in a more marketable beef product. However, without successful pregnancies, there would be no marketable animals to feed. Despite extensive research on hormonal impacts on cattle physiology, including nutrition and reproduction, there is limited knowledge about how the rumen microbial environment is impacted by pregnancy and feed efficiency in female beef cattle. Understanding the rumen microbiome's role in feed efficiency and its response to hormonal changes during pregnancy is crucial for advancing sustainable beef cattle production. Therefore, this review highlights the importance of understanding the microbial dynamics in the rumen of pregnant beef females. Although progress has been made, gaps remain in understanding how varying nutritional requirements throughout pregnancy affect the rumen microbiome, highlighting the need for continued research. Addressing these areas will lead to more efficient and sustainable cattle production practices, benefiting beef production and contributing to global food security. [ABSTRACT FROM AUTHOR]

Folate metabolism is required for important biochemical processes that regulate cell functioning, but its role in female reproductive physiology in cattle during peri- and post-conceptional periods has not been thoroughly explored. Previous studies have shown the presence of folate in bovine oviductal fluid, as well as finely regulated gene expression of folate receptors and transporters in bovine oviduct epithelial cells (BOECs). Additionally, extracellular folic acid (FA) affects the transcriptional levels of genes important for the functioning of BOECs. However, it remains unknown whether the anatomical and cyclic features inherent to the oviduct affect regulation of folate metabolism. The present study aimed to characterize the gene expression pattern of folate cycle enzymes in BOECs from different anatomical regions during the estrous cycle and to determine the transcriptional response of these genes to increasing concentrations of exogenous FA. A first PCR screening showed the presence of transcripts encoding dihydrofolate reductase (DHFR), methylenetetrahydrofolate reductase (MTHFR), and methionine synthase (MTR) in bovine reproductive tissues (ovary, oviduct and uterus), with expression levels in oviductal tissues comparable to, or even higher than, those detected in ovarian and uterine tissues. Moreover, expression analysis through RT-qPCR in BOECs from the ampulla and isthmus during different stages of the estrous cycle demonstrated that folate metabolism-related enzymes exhibited cycle-dependent variations. In both anatomical regions, DHFR was upregulated during the preovulatory stage, while MTHFR and MTR exhibited increased expression levels during the postovulatory stage. Under in vitro culture conditions, ampullary and isthmic cells were cultured in the presence of 10, 50, and 100 μM FA for 24 h. Under these conditions, isthmus epithelial cells exhibited a unique transcriptional response to exogenous FA, showing a pronounced increase in MTR expression levels. Our results suggest that the expression of folate metabolism-related genes in BOECs is differentially regulated during the estrous cycle and may respond to exogenous levels of folate. This offers a new perspective on the transcriptional regulation of genes associated with the folate cycle in oviductal cells and provides groundwork for future studies on their functional and epigenetic implications within the oviductal microenvironment. • Genes related to folate metabolism enzymes are expressed in bovine oviduct ephitelial cells (BOECs). • DHFR , MTHFR , and MTR expression levels exhibit cycle-dependent variations in BOECs from ampulla and isthmus regions. • MTR is upregulated in isthmus cells cultured with increasing levels of folic acid. • Folate metabolism could have important functional and epigenetic implications in the bovine oviduct. [ABSTRACT FROM AUTHOR]

Simple Summary: Cattle are increasingly exposed to high temperatures with accelerating climate change, presenting the risks of heat stress, poor welfare, and even death. In Australia, the sudden onset of extreme conditions means that deaths are not uncommon. Understanding the impact of high environmental temperatures on cattle behaviour and physiology is critical. We aimed to investigate changes in infrared eye temperature and their association with behavioural responses, such as changes in body postures, alterations in feeding behaviour, and body self-care. Twenty-four Angus steers were individually housed to assess heat load responses when they were fed either a standard finisher diet based on cereal grains or an alternative diet with 8% of the grains replaced by an isoenergetic amount of lucerne hay. No differences were observed between different dietary cohorts. The infrared eye temperature (IRT-Eye), of the steers exposed to high environmental temperatures was increased, and this had a strong association with behaviour and physiology. Cattle with increased IRT-Eye temperature showed stress-related behavioural responses, including a downward-facing head, ears directed backwards, and other indicators of heat stress such as increased panting, standing, and increased rumen temperature. The strong association of IRT-Eye with behaviour and physiology suggests that it can be used to detect heat stress in cattle. Cattle in regions with high ambient temperatures are at risk of heat stress. Early detection is important to allow action to be taken to minimise the risks to cattle exposed to thermal stress. This study aimed to investigate the impact of heat stress on IRT-Eye temperature and its association with the behavioural and physiological responses of heat-stressed Angus steers (n = 24) on finisher and or substituted diets. Overall, 2 cohorts of 12 Angus steers were individually housed in a climate-controlled facility to examine responses to heat stress when fed on a standard finisher diet, based on a high percentage of cereal grains, and on a substituted diet in which 8% of the grains were replaced by an isoenergetic amount of lucerne hay. Exposing feedlot cattle to hot environmental conditions increased IRT-Eye temperature, which had a strong association with behaviour and physiology. There was no evidence of differences between the different dietary cohorts. The cattle with increased IRT-Eye temperature showed stress-related responses, including a downward-facing head, ears directed backwards, and other indicators of heat stress such as increased panting, standing, and increased rumen temperature. The strong association of IRT-Eye temperature with stress-related behaviours, as well as with rumen temperature and panting behaviour, highlights the potential for IRT-Eye to be utilised as a non-invasive tool to assess cattle responses in hot conditions. [ABSTRACT FROM AUTHOR]

Genome-wide association studies (GWAS) significantly enhance our ability to identify trait-associated genomic variants by considering the host genome. Moreover, the hologenome refers to the host organism's collective genetic material and its associated microbiome. In this study, we utilized the hologenome framework, called Hologenome-wide association studies (HWAS), to dissect the architecture of complex traits, including milk yield, methane emissions, rumen physiology in cattle, and gut microbial composition in pigs. We employed four statistical models: (1) GWAS, (2) Microbial GWAS (M-GWAS), (3) HWAS-CG (hologenome interaction estimated using COvariance between Random Effects Genome-based restricted maximum likelihood (CORE-GREML)), and (4) HWAS-H (hologenome interaction estimated using the Hadamard product method). We applied Bonferroni correction to interpret the significant associations in the complex traits. The GWAS and M-GWAS detected one and sixteen significant SNPs for milk yield traits, respectively, whereas the HWAS-CG and HWAS-H each identified eight SNPs. Moreover, HWAS-CG revealed four, and the remaining models identified three SNPs each for methane emissions traits. The GWAS and HWAS-CG detected one and three SNPs for rumen physiology traits, respectively. For the pigs' gut microbial composition traits, the GWAS, M-GWAS, HWAS-CG, and HWAS-H identified 14, 16, 13, and 12 SNPs, respectively. We further explored these associations through SNP annotation and by analyzing biological processes and functional pathways. Additionally, we integrated our GWA results with expression quantitative trait locus (eQTL) data using transcriptome-wide association studies (TWAS) and summary-based Mendelian randomization (SMR) methods for a more comprehensive understanding of SNP-trait associations. Our study revealed hologenomic variability in agriculturally important traits, enhancing our understanding of host-microbiome interactions. [ABSTRACT FROM AUTHOR]

Background: The Rembi sheep breed is renowned for its exceptional meat quality and significant economic profit. Nevertheless, there is a gap in research on the hepatic parameters of this breed in Algeria despite the considerable value of the liver in the Algerian population's diet. Objectives: The research aimed to determine the impact of physiological factors (age, physiological stage, and body condition score) on biochemical sheep liver parameters. Methods: Sixty clinically healthy female Rembi breed sheep, aged between 3 months and 7 years, raised at the Technical Institute of Livestock (ITELV) Ksar Chellala Farm in Tiaret Province, Algeria, were selected for biochemical analysis and assessing aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), total bilirubin (TBIL), direct bilirubin (DBIL), albumin (ALB), and total protein (TP). Results: The concentrations of AST, ALP, and GGT increased significantly (P≤0.001) in young sheep, while ALT and TP levels decreased (P≤0.05). However, a high level of GGT (P<0.001) was also observed in lactating ewes, and during pregnancy, females have a low level of ALP (P<0.001). Furthermore, the body condition score does not affect any of the measurements. Conclusion: Considering the animal's age and physiological stage is critical before interpreting the results. [ABSTRACT FROM AUTHOR]

Simple Summary: Japanese black cattle are a well-known Wagyu cattle breed in Japan, with the best-producing carcass. Based on previous studies and the literature, the existence of the internal carotid artery in cattle still needs to be determined. Thus, this research examined the arterial supply in the brains of Japanese black cattle, especially the presence of the internal carotid artery and its closure at different ages. The internal carotid artery (ICA) is a branch of the common carotid artery (CCA), along with the external carotid artery (ECA), which together provide the blood supply for the brain. The description of the ICA in cattle is vague, including denial of its existence or degeneration at an early stage after birth. This anatomical study investigated the internal carotid artery in Japanese black cattle. Sixty-five heads of Japanese black cattle aged from newborn to 13 years were dissected and injected with colored latex from the CCA after separating the head and body. Diameter measurements of the artery branches from the CCA on its bifurcation were conducted. Furthermore, a histological examination of the ICA wall's structures, which consist of the tunica intima, tunica media, and tunica externa, was performed. The ICA of Japanese black cattle is closed on the left side after age 3 years, except for a small lumen at 13 years, whereas the right ICA remains open at all ages. The location of occlusion of the left internal carotid artery (LICA) shows thickness of the tunica intima and an increased connective tissue layer area. The diameter of the ICA does not differ between the left and right sides, and there is no correlation with age. Therefore, further studies are needed, especially of ICA occlusion related to Japanese black cattle's physiology or cerebrospinal disease. [ABSTRACT FROM AUTHOR]

Sustainable livestock systems should provide high production yields while respecting animal welfare. The silvopastoral system (SPS: silvopastoral-trees, pasture, and cattle) offers a more holistic cattle management strategy, than only pasture system (PAS). The SPS incorporates the production of wood and forage, offering protection for the animals while grazing. However, the relationship between animal behavioral indicators in the SPS has been poorly studied in subtropical conditions. The present study was established to investigate the effect of the SPS on the physiological, behavioral, and health responses during one grazing cycle of the Purunã cattle. Thirty heifers were randomly assigned into two groups of 15 animals, either kept on the SPS or under a monoculture system (PAS: pastoral-cattle on pasture). Body weight and body surface temperature, time of grazing, and lying behavior were assessed for both systems during late Autumn (40 days) in a subtropical humid region of Brazil. The data showed a statistically significant influence of the SPS on the reduction of the heifers’ average body surface temperature, from 27.7 oC to 30.3 oC in PAS (P = 0.02). Although there was an important effect of the SPS on decreasing eating behavior (4.77 events/1.5 h), compared to animals kept in the PAS (6.21 events/1.5 h), the differences in forage availability and quality may have played a role in the animals kept in the SPS. Animals in the SPS presented statistically significantly fewer drinking (P = 0.0001) events, higher body condition score (BCS) decline (P = 0.02), and Rhipicephalus microplus (cattle-tick) score (P = 0.009), than animals maintained on the PAS. There was an aggregated tick distribution, and infested animals lost (high tick score) significantly more weight (P = 0.0216) than non-infested ones (low tick score) under SPS conditions. More studies are required to understand better the influence of multiple factors on Purunã behavior and health, especially when considering distinct agricultural systems, forage availability, geographical and subtropical-humid (Cfb) climate conditions, and the impact of ectoparasites on animal performance. [ABSTRACT FROM AUTHOR]

Simple Summary: Rumination is important for the digestive physiology of cattle and can currently be continuously recorded by sensor technologies. Although a decrease in rumination time is associated with several disorders, it often does not lead farmers to take specific action. In this study, we monitored rumination activity with the use of an ear-tag-based accelerometer system. To investigate the association between a decrease in rumination time and the digestive physiology of dairy cows, we compared rumen fluid characteristics between cows with accelerometer-based health alerts and matched healthy counterparts. Cows with health alerts showed greater variations in rumen fluid characteristics during the health alerts than healthy cows. Monitoring rumination activity is considered a useful indicator for the early detection of diseases and metabolic disorders. Accelerometer-based sensor systems provide health alerts based on individual thresholds of rumination times in dairy cows. Detailed knowledge of the relationship between sensor-based rumination times and rumen physiology would help detect conspicuous animals and evaluate the treatment's success. This study aimed to investigate the association between sensor-based health alerts and rumen fluid characteristics in Holstein-Friesian cows at different stages of lactation. Rumen fluid was collected via a stomach tube from 63 pairs of cows with and without health alerts (ALRT vs NALRT). Pairs were matched based on the day of lactation, the number of lactations, and health criteria. Rumen fluid was collected during and after health alerts. The parameters of color, odor, consistency, pH, redox potential, sedimentation flotation time, and the number of protozoa were examined. Results showed differences between both groups in odor, rumen pH, sedimentation flotation time, and protozoan count at the first rumen fluid collection. Within the groups, greater variations in rumen fluid parameters were found for ALRT cows compared to NALRT cows. The interaction between health alert and stage of lactation did not affect the rumen fluid parameters. [ABSTRACT FROM AUTHOR]

Simple Summary: The general consensus on maternal behavior in free-ranging beef cattle was reviewed. Factors which may affect the display of these behaviors were also explored and provide important information relevant to calf survival and performance. A key aspect of the maternal instinct in all mammals relates to an intricate interplay of various hormones and neurotransmitters around the time of parturition. The influence of these hormones on regulating and initiating maternal behavior in a number of species were also described to provide unique insights for predicting maternal behavior in cattle. Lastly, current methods of measuring behavior were additionally summarized. Bovine maternal behavior is known to be influenced by a variety of factors including hormonal mediation, breed, age, parity, host genetics and general management practices. Following centuries of varying levels of domestication processes, the behavior of the bovine cow has altered from that of her original wild ungulate ancestors, although many maternal instincts have remained unchanged. The influence of maternal behavior on calf health and performance is of interest to cow-calf beef production operations, as in most instances, the cow is solely responsible for rearing the calf until weaning. However, investigating the magnitude of this influence is challenging, in part because objective measurement of behavioral traits is difficult, particularly in extensive settings. In recent years, while a number of remote monitoring devices have been developed that afford opportunities for objective measurement of behavioral traits in livestock, characterization of physiological mechanisms that underlie superior maternal behavior, including identification of potential biomarkers remains elusive in cattle. Hormonal profiles during the periparturient period have been shown to influence behavioral patterns in both current and future generations in other mammalian species and may provide insights into the physiology of bovine maternal behavior. Therefore, the aim of this review is to describe general characteristics of bovine maternal behavior and the factors known to influence it, including hormonal drivers, through which cross-reference to other species is made. Current methods of measuring and assessing behavior that may also be applicable to most production settings have also been reviewed. At present, there is no known hormonal assay that can be used to measure and/or reliably predict bovine maternal behavior post-calving or across generations. Being able to objectively assess superior maternal behavior, whether that be through remote monitoring, hormonal profiling or indirectly through measuring calf performance will be beneficial to livestock industries in the future. [ABSTRACT FROM AUTHOR]

Climate change affects animal physiology. In particular, rising ambient temperatures reduce animal vitality due to heat stress and this can be observed at various levels which included genome, transcriptome, and microbiome. In a previous study, microbiota highly associated with changes in cattle physiology, which included rectal temperature, drooling score and respiratory score, were identified under heat stress conditions. In the present study, genes differentially expressed between individuals were selected representing different additive genetic effects toward the heat stress response in cattle in their production condition. Moreover, a correlation network analysis was performed to identify interactions between the transcriptome and microbiome for 71 Chinese Holstein cows sequenced for mRNA from blood samples and for 16S rRNA genes from fecal samples. Bioinformatics analysis was performed comprising: i) clustering and classification of 16S rRNA sequence reads, ii) mapping cows' transcripts to the reference genome and their expression quantification, and iii) statistical analysis of both data types--including differential gene expression analysis and gene set enrichment analysis. A weighted co-expression network analysis was carried out to assess changes in the association between gene expression and microbiota abundance as well as to find hub genes/microbiota responsible for the regulation of gene expression under heat stress. Results showed 1,851 differentially expressed genes were found that were shared by three heat stress phenotypes. These genes were predominantly associated with the cytokine-cytokine receptor interaction pathway. The interaction analysis revealed three modules of genes and microbiota associated with rectal temperature with which two hubs of those modules were bacterial species, demonstrating the importance of the microbiome in the regulation of gene expression during heat stress. Genes and microbiota from the significant modules can be used as biomarkers of heat stress in cattle. [ABSTRACT FROM AUTHOR]

Ruminant species are important to human society due to their ability to convert human-inedible sources of energy and protein to human-edible food. Greater efficiency of meat and milk production will require the management of the complex reproductive biology of many cattle with a limited capacity and limited budget within a smaller, hotter, and more climatically erratic land area. The over-riding drivers of new reproductive technologies in North America will be smaller economic margins, larger herd size, fewer agricultural workers per farm, and a greater reliance on automation to offset the reduced agricultural labor force. Climate change and the possibility that consumers may dictate the procedures used for animal reproductive management may present additional challenges. The successes of the past 20 years (timed AI, genomic selection for fertility in both bulls and cows, automated estrus detection, chemical and ultrasonographic pregnancy diagnosis, and gender selected semen) will be improved upon in the next 20 years as most of these technologies can be optimized further. Improving embryo technologies and increasing our understanding of embryonic loss may provide the greatest challenges for the future. Researchers must attempt to devise practical methods to release more follicles from the primordial follicle pool so that a greater number of oocytes and embryos can be harvested from individual animals. Embryonic loss continues to be an unsolved question that cuts the total number of potential offspring by nearly one-third. The identification of fertile embryos in vitro, better methods of cryopreservation, and the optimization of methods of transfer into recipient animals may improve the efficiency of advanced embryo technologies. The derivation of oocytes, sperm, and embryos from pluripotent stem cells may yield a vast supply of gametes and embryos from genetically superior animals and radically change the reproductive management in the future., Competing Interests: Declaration of competing interest The authors claim no conflict for the content of this article., (Copyright © 2024 Elsevier Inc. All rights reserved.)

By 2050, the U.S. beef industry must produce an extra 40 million tons of beef to satisfy the global demand. Such an increase in inventory will undoubtedly enhance methane (CH4) production from livestock, which should be reduced by over 20%. The addition of plant secondary metabolites, such as anacardic acid present in cashew nutshell extract (CNSE), has shown promising results in reducing CH4 yield, although its effects seemed to be diet-dependent. This study evaluated the addition of CNSE to a high-grain diet (85:15 grain:forage) on in vivo CH4 emissions, nutrient digestibility, performance, feeding behavior, and ruminal fermentation parameters of beef steers. Sixteen Angus crossbred steers [599 ± 40 kg of bodyweight (BW)] and 6 ruminally cannulated crossbred steers (490 ± 51 kg of BW) were utilized in a crossover design with 2 experimental periods of 56 d each, composed by 14 d of adaptation, 35 d of measurement, and 7 d of washout. Following adaptation, steers were sorted by BW, and assigned to receive no additive (CON) or CNSE at 5 g/steer/d. Data were analyzed using the MIXED procedure of SAS. Inclusion of CNSE increased (P < 0.05) propionate concentration and molar proportion (MP; mol/100 mol), tended to decrease acetate MP (P = 0.10), reduced the acetate:propionate (A:P) ratio (P = 0.05), and MP of branched-chain volatile fatty acids (P < 0.01). Neither in vitro organic matter digestibility nor in vitro CH4 yield were affected by CNSE inclusion (P > 0.05). Steers receiving CNSE exhibited greater (P < 0.05) final BW, dry matter intake (DMI), and average daily gain (ADG) but lesser (P < 0.05) in vivo CH4 emission rate (g/d), yield (g/kg of DMI), and intensity (g/kg of ADG). Meal length, bunk visit duration, and apparent total tract digestibility of DM increased (P < 0.05) after CNSE addition. Considering CNSE-supplemented steers spent more time in the feedbunk and exhibited higher DMI, CH4 mitigation was unlikely associated with intake reduction. The addition of CNSE to a high-grain diet in beef steers demonstrated significant improvements in animal performance and reduced CH4 emissions, as the result of shifts in ruminal fermentation patterns, favoring propionate instead of acetate concentration, leading to a reduction in the A:P ratio. CNSE shows promise as a strategy to enhance beef industry sustainability., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The current study was designed to evaluate the effect of particle size (PS) and inclusion level of wheat straw (WS) obtained from genetically improved wheat on the performance and feeding behavior of Sahiwal cows. Twelve multiparous, mid-lactating Sahiwal cows (DIM 135 ± 25, mean ± SD; 12.8 ± 1.6 kg/d milk, 331 ± 21 kg of BW) were split into groups of 4 and subjected to each of four treatments in a 2*2 cross-over design. For experimental diets, TMR differed in the length and inclusion level of the WS component in that diet, (1) straw chopped with a 2 cm screen (Fine chopped- FC, and inclusion, i.e., FCA = 20% and FCB = 30%) or (2) straw chopped with a 4 cm screen (long chopped-LC, and inclusion, i.e., LCA = 20% and LCB = 30%). The increased dry matter (DM) intake (9.10 kg/d) and crude protein (CP) intake (1.25 kg/d) were observed in FCA. The diets with the shorter PS and higher inclusion (i.e., FCB) exhibited higher neutral detergent fibre (NDF) intake (3.77 kg) and acid detergent fibre (ADF) intake (2.72 kg). The findings of digestibility showed higher DM-digestibility in LCA (55.24%). Meanwhile, the higher digestibility of CP (52.9%) and ADF (36%) was found in LCB, and NDF (38.5%) was observed in LCA. Moreover, cows receiving FCA diets showed improved milk (15.5 kg/d), 3.5%FCM (17.76 kg/d), fat (0.683/d Kg), and protein (0.516 kg/d) yields and production efficiency. However, the milk composition was improved in cows fed with LCB diets. Furthermore, the behavioural activities showed higher eating (i.e., 228.3 min/day), rumination (391 min./day), and chewing (617.9 min./day) activities in LCB diets. Whereas, the lying activity (568.5 min/day) was greater in FCA-fed cows. Our study suggests that incorporating fine-chopped WS @ 20% improves the overall production performance and feeding behavior of the cows., Competing Interests: Declarations. Ethical statement: All the experimental procedures were approved by the Institutional Animal Care and Use Committee of the Institute of Animal and Dairy Sciences and the Director of Graduate Studies at the University of Agriculture, Faisalabad (Permit Number: DGS/16421–24, dated 22–05–2023). Conflicts of interest: The author declares no conflicts of interest., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

In tropical beef cattle production systems, animals are commonly raised on pastures, exposing them to potential stressors. The end of gestation typically overlaps with a dry period characterized by limited food availability. Late gestation is pivotal for fetal development, making it an ideal scenario for inter- and transgenerational effects of the maternal gestational environment. Intergenerational effects occur due to exposure during gestation, impacting the development of the embryo and its future germline. Transgenerational effects, however, extend beyond direct exposure to the subsequent generations. The objective of the present study was to verify these effects on the post-natal performance of zebu beef cattle. We extended the use of a reaction norm model to identify genetic variation in the animals' responses to transgenerational effects. The inter- and transgenerational effects were predominantly positive (-0.09% to 19.74%) for growth and reproductive traits, indicating improved animal performance on the phenotypic scale in more favourable maternal gestational environments. Additionally, these effects were more pronounced in the reproductive performance of females. On average, the ratio of direct additive genetic variances of the slope and intercept of the reaction norm ranged from 1.23% to 3.60% for direct and from 10.17% to 11.42% for maternal effects. Despite its relatively modest magnitude, this variation proved sufficient to prompt modifications in parameter estimates. The average percentage variation of direct heritability estimates ranged from 19.3% for scrotal circumference to 33.2% for yearling weight across the environmental descriptors evaluated. Genetic correlations between distant environments for the studied traits were generally high for direct effects and far from unity for maternal effects. Changes in EBV rankings of sires across different gestational environments were also observed. Due to the multifaceted nature of inter- and transgenerational effects of the maternal gestational environment on various traits of beef cattle raised under tropical pasture conditions, they should not be overlooked by producers and breeders. There were differences in the specific response of beef cattle to variations in the quality of the maternal gestational environment, which can be partially explained by transgenerational epigenetic inheritance. Adopting a reaction norm model to capture a portion of the additive variance induced by inter- or transgenerational effects could be an alternative for future research and animal genetic evaluations., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Background: During the transitional period, dairy cows experience oxidative stress and are more susceptible to diseases, including left displacement of the abomasum (LDA)., Objectives: This study aimed to compare oxidative stress biomarker levels in cows with LDA to those in healthy conditions and investigate the associations between predictive metabolites linked to LDA and oxidative stress biomarkers., Methods: In this case-control study, 400 healthy multiparous Holstein cows were matched for lactation number, milk production and calving date. Blood samples were collected at four time points: 21 and 7 days before, as well as 7 and 21 days after parturition from all animals. During the observation period, seven cows diagnosed with LDA in the main population, and seven healthy cows were randomly selected as controls for the comparison of oxidative stress, liver enzymes and metabolic parameters. Analysis of blood parameters utilized repeated measures ANOVA, and the degree of relationship between oxidative stress biomarkers and other measured parameters was assessed using Pearson correlations., Results: The LDA group exhibited significantly higher levels of urea, blood urea nitrogen (BUN), gamma-glutamyl transferase, glucose, cholesterol, triglyceride (TAG), β-hydroxybutyric acid (BHBA), aspartate aminotransferase (AST), sorbitol dehydrogenase, serum amyloid A (SAA), chloride, sodium, potassium, total antioxidant capacity (TAC) and malondialdehyde (MDA) compared to the control cows (p < 0.05). Positive correlations were observed among BUN, glucose, TB, AST, SAA, BHBA, TAG and MDA. Conversely, these parameters displayed negative correlations with TAC. Negative correlations were found among chloride, sodium, potassium, calcium, phosphorus and MDA, whereas positive correlations were observed with TAC., Conclusions: These findings highlight the elevated level of oxidative stress and compromised antioxidant defence in cows with LDA and the intricate interplay among oxidative stress, metabolic parameters and liver enzymes., (© 2024 The Author(s). Veterinary Medicine and Science published by John Wiley & Sons Ltd.)

Regulatory T cells (Tregs) have emerged as crucial players in maintaining maternal-fetal tolerance and promoting successful pregnancy outcomes. This review examines the importance of these cells in pregnancy, drawing on human and animal-based studies, with a focus on their role in bovine fertility. Tregs employ various mechanisms to mediate maternal-fetal tolerance, including regulation of effector T-cell responses, interactions with innate immune cells in the uterine microenvironment, and modulation of trophoblast function. In humans, Treg dynamics during normal pregnancy and alterations in pregnancy complications provide compelling evidence for their involvement in maintaining fetal-maternal harmony. Animal models, particularly mouse studies, have further elucidated the importance of Tregs in preventing fetal rejection and promoting successful pregnancy outcomes. The review also explores the characterization of bovine Tregs, highlighting their similarities and unique features compared to human and rodent counterparts. Recent studies have indicated the presence and potential significance of Tregs in the bovine uterine environment during early pregnancy. Translational applications of Treg research in livestock fertility are discussed, with a focus on immunomodulatory strategies for enhancing Treg function, such as antigen-specific tolerance induction, pharmacological targeting of Treg pathways, and cell-based therapies using autologous or allogeneic Tregs. The review concludes by emphasizing the potential impact of Treg-based strategies on the livestock industry and the broader implications for human reproductive health. Future research directions are outlined, underscoring the need for further investigations into the role of Tregs in bovine reproductive tissues and their relationship with fertility outcomes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The objective of this study was to evaluate changes in longissimus dorsi muscle depth (LDD) across lactation (0 to 300 DIM) and identify the effect of low versus high muscle reserves immediately after parturition on BW and body reserve changes as well as production variables across a 300-d lactation. Forty multiparous cows were classified as high muscle (HM; LDD > 5.0 cm; n = 18) or low muscle (LM; LDD ≤ 5.0 cm; n = 22) based on LDD measurements collected within 24 h of parturition. Body weights and ultrasound scans to assess LDD and back fat depth (BFD) were collected monthly from parturition until 300 DIM. Ultrasound scans captured and measured using available software. Blood samples were taken at 7, 150 and 300 DIM, and plasma was analyzed for markers of metabolic status by measuring insulin, nonesterified fatty acids (NEFA), creatinine, and 3-methylhistidine (3-MH). Milk yield was recorded daily and milk components were analyzed monthly. Data analysis was performed and the statistical models included the fixed effect of muscle group, time, their interaction, and the random effect of cow nested within muscle group with repeated measures using a first-order autoregressive covariance structure. Muscle group was not related to BW or BFD for any of the time points measured. Cows lost BW from 0 to 60 DIM and gained weight from 60 to 300 DIM. Similarly, BFD decreased between 0 to 90 DIM and increased BFD after 90 DIM until 300 DIM. A muscle group by time interaction was observed for LDD. The HM cows had more muscle at 0 DIM, indicative of treatment assignment (1.34 cm more), and 300 DIM (0.78 cm more) and tended to have more muscle at 60 DIM (0.66 cm more) compared with LM. After 240 DIM, both muscle groups began net accretion of muscle reserves until 300 DIM. No differences were observed for blood metabolites measured based on muscle group. However, significant time effects for creatinine, 3-MH, and NEFA concentrations existed, which reflected the observed changes in BFD and LDD measured in ultrasound scans. For statistical analysis of daily milk production, observations were grouped into 3 stages of lactation, early (0-60 DIM), mid (60-240 DIM), and late lactation (240-300 DIM). A muscle group by stage of lactation interaction was present, where in early and mid-lactation, HM cows produced, on average, 1.9 kg more milk/d; however, in late lactation, LM cows produced 1.8 kg more milk/d. Our results indicate that muscle reserves are depleted in early lactation, and accreted in late lactation, whereas BW and BFD started to increase by 90 DIM. Data also supports that cows with more extensive muscle depletion in early lactation had greater milk production, however, substantial muscle accretion in late lactation may result in reduced milk production., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

This study utilized Bayesian inference in a genome-wide association study (GWAS) to identify genetic markers associated with traits relevant to the adaptation of Hereford and Braford cattle breeds. We focused on eye pigmentation (EP), weaning hair coat (WHC), yearling hair coat (YHC), and breeding standard (BS). Our dataset comprised 126,290 animals in the pedigree. Out of these, 233 sires were genotyped using high-density (HD) chips, and 3750 animals with medium-density (50 K) single-nucleotide polymorphism (SNP) chips. Employing the Bayes B method with a prior probability of π = 0.99, we identified and tagged single nucleotide polymorphisms (Tag SNPs), ranging from 18 to 117 SNPs depending on the trait. These Tag SNPs facilitated the construction of reduced SNP panels. We then evaluated the predictive accuracy of these panels in comparison to traditional medium-density SNP chips. The accuracy of genomic predictions using these reduced panels varied significantly depending on the clustering method, ranging from 0.13 to 0.65. Additionally, we conducted functional enrichment analysis that found genes associated with the most informative SNP markers in the current study, thereby providing biological insights into the genomic basis of these traits., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

This study aimed to evaluate the effects of early group housing on the performance, health, and behavior of dairy calves during the preweaning period using systematic and meta-analysis approaches. Peer-reviewed articles written in English that compared dairy calves individually and group-housed with performance, health, or behavior outcomes were collected from Web of Science, PubMed, and CABDirect databases. The resulting articles (n = 850) underwent a 4-step appraisal process following the Preferred Reporting Items for Systematic Review and Meta-Analyses protocols, resulting in a final sample of 51 articles containing 85 studies. The weighted or standardized mean differences between individually housed and group-housed (pair or group with >2 calves) calves were analyzed for each variable using the DerSimonian and Laird methods. Heterogeneity between calf housing systems was evaluated by the χ 2 test and I 2 statistics. A meta-regression analysis was conducted to identify categorical covariate effects for variables with high heterogeneity. Most of the studies included in this review evaluated female calves (45.8%) weaned at 8 wk old (52.6%). Housing systems were mainly paired housing (55.3%), followed by groups of 3 to 6 calves (30.65) and groups of 7 to 15 calves (4.7%). We did not find studies with comparable outcomes for more robust health parameters (as occurrence of diseases), only blood parameters, that were not influenced by the housing system. However, weight gain and feed intake parameters were higher in group-housed calves. Through the meta-regression, we found that ADG was positively affected by the group housing in studies with calves housed in small pen areas (<1.5 m 2 per calf). Group-housed calves presented more active behaviors (feeding and playing) and less stress-related behaviors (self-grooming and interacting with the pen) than individually housed calves. The behavioral tests most used were novel object, human approach, novel environment, and social tests. Individually housed calves presented fewer vocalizations on these tests and spent more time interacting with humans during the human approach test than group-housed calves. Our findings provide consistent evidence that group housing improves the welfare of dairy calves; however, the effects on health parameters are still scarce and unclear., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

This experiment assessed pregnancy losses from day 31 of gestation to calving in lactating Holstein cows reared in tropical conditions, and evaluated if serum concentrations of haptoglobin and pregnancy-associated glycoproteins (PAGs) during early gestation differs according to pregnancy losses. Cows (708 primiparous and 844 multiparous) were assigned to an ovulation synchronization + fixed-time artificial insemination (FTAI) protocol (day -11-0 of the experiment). Pregnancy status was verified using transrectal ultrasonography on days 31, 62, 120, and according to calf birth. Blood samples were collected from all cows on day 24, and from cows diagnosed as pregnant on day 31. Pregnancy losses were greater (P < 0.01) from day 31-62 (12.8 %) and day 120 to calving (12.1 %) compared with day 62-120 (6.42 %). Pregnancy losses were greater in multiparous compared with primiparous cows from day 31-62 (17.1 vs. 9.5 %) and from 120 to calving (15.4 vs. 7.7 %). Serum PAGs concentrations on day 31 were less (P ≤ 0.03) in cows that lost the pregnancy from day 31-62 (3.57 ng/mL) and from day 62-120 (4.40 ng/mL) compared to cows that maintained the pregnancy (5.57 and 5.66 ng/mL, respectively). Cows that experienced pregnancy loss from day 31-62 had greater (P = 0.05) serum haptoglobin concentrations on day 24 (0.414 mg/mL) compared with cows that maintained the pregnancy (0.271 mg/mL). Collectively, this experiment provides novel information about pregnancy losses after day 31 of gestation in lactating Holstein cows reared in tropical environments., Competing Interests: Declaration of competing interest Nothing to declare., (Copyright © 2024 Elsevier B.V. All rights reserved.)

India is the largest milk producer contributing 25 % to the global production. From a mere 17 million tons (MTs) in 1951, milk production increased to an inconceivable 230 MTs in 2023. Nondescript cows and buffaloes were the main milk animals. Since 1965, nationwide programs for cross breeding native cattle with exotic milk breeds such as Jersey, Holstein Friesian (HF) and Brown Swiss (BS) and upgradation of buffalo breeds along with disease eradication, feed and fodder development and provision of veterinary and extension services were implemented. Now 75 % of the milk in India is produced by the native, exotic and crossbred cows (43 %) and native breeds of buffaloes (32 %). National Dairy Development Board (NDDB) created dairy cooperatives, an Indian innovation to connect rural milk producers to urban and semi-urban consumers. These cooperatives transformed subsistence dairy farming into a profitable rural enterprise and created millions of jobs. Due to the success of the above activities, since 1998 India continues to produce the highest volumes of milk in the world. It is envisioned to increase (i) milk production to 450 million tons (MTs) (one-third of the global production) (ii) gain a share of 15 % in global milk and milk products exports and (iii) build sustainable green practices to match global standards during the next 25 years. India is increasingly deploying artificial insemination (AI) with sex sorted-frozen semen, embryo transfer and in vitro production of embryos using sex sorted semen, progeny testing and genomic selection to improve reproduction and productivity among dairy animals. Mitigation of disease burden is undertaken through nationwide vaccination against diseases such as Foot and Mouth, TB, Brucellosis etc. Nutritious fodder crops and feed additives that support higher productivity and reduce enteric methane emissions are promoted. Management and interventional practices such as better nutrition, amelioration of summer stress, oestrus synchronisation etc., are increasingly implemented. Use of internet enabled technology services (IETS) for extension activities, mobile veterinary and animal husbandry services are rapidly becoming commonplace. All these practices portend greater achievements in milk production in the fore-seeable future. Achievements, aspirations, accosts, approaches and appraisal are presented., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Temperament (docility) is a key breeding goal in the cattle industry due to its direct relationship with animal welfare, cattle handler's safety and animal productivity. Over the past six decades, numerous studies have reported heritability estimates for temperament-related traits in cattle populations ranging from low to high values. Therefore, the primary objective of this study was to perform a comprehensive systematic review with meta-analysis to obtain weighted estimates of heritability for temperament-related traits in worldwide cattle populations. After data editing and quality control, 106 studies were included in the systematic review, of which 29.2% and 70.8% reported estimates of heritability for temperament-related traits in dairy and beef cattle populations, respectively. Meta-analyses were performed for 95 heritability estimates using a random model approach. The weighted heritability estimates were as follow: (a) flight score at weaning = 0.23 (95% CI: 0.15-0.32); (b) flight speed at weaning = 0.30 (95% CI: 0.26-0.33); (c) joint analysis of flight speed and flight score at weaning = 0.27 (95% CI: 0.22-0.31); (d) flight speed at yearling = 0.26 (95% CI: 0.21-0.30); (e) joint analysis of flight speed at weaning and yearling = 0.27 (95% CI: 0.24-0.30); (f) movement score = 0.12 (95% CI: 0.08-0.15); (g) crush score at weaning = 0.21 (95% CI: 0.17-0.25); (h) pen score at weaning = 0.27 (95% CI: 0.19-0.34); (i) pen score at yearling = 0.20 (95% CI: 0.17-0.23); (j) joint analysis of pen score at weaning and yearling = 0.22 (95% CI: 0.18-0.26); (k) cow's aggressiveness at calving = 0.10 (95% CI: 0.01-0.19); (l) general temperament = 0.13 (95% CI: 0.06-0.19); (m) milking temperament = 0.16 (95% CI: 0.11-0.21); and (n) joint analysis of general and milking temperament = 0.14 (95% CI: 0.11-0.18). The heterogeneity index ranged from 0% to 77%, and the Q-test was significant (p < 0.05) for four single-trait meta-analyses. In conclusion, temperament is moderately heritable in beef cattle populations, and flight speed at weaning had the highest weighted heritability estimate. Moreover, between-study heterogeneity was low or moderate in beef cattle traits, suggesting reasonable standardization across studies. On the other hand, low-weighted heritability and high between-study heterogeneity were estimated for temperament-related traits in dairy cattle, suggesting that more studies are needed to better understand the genetic inheritance of temperament in dairy cattle populations., (© 2024 The Author(s). Journal of Animal Breeding and Genetics published by John Wiley & Sons Ltd.)

Efficient and sustainable reproduction and production of cattle and goats are vitally important for ensuring global food security. There is a need for potent biomarkers to accurately evaluate semen quality and predict male fertility. Although there is a reasonable set of biomarkers identified in bull sperm, there is a significant lack of such information in buck sperm along with a lack of transfer of proven technologies in goat reproductive biotechnology. These gaps are important problems because they are preventing advances in fundamental andrology and applied science of goat production. Both cattle and goats are ruminants, and they share significant similarities in their genetics and physiology although subtle differences do exist. This review harnesses the power of utilizing the knowledge developed in bull sperm to generate information on buck sperm fertility markers. These include genomic, functional genomic, epigenomic fertility markers. Revealing molecular underpinnings of such similarity and diversity using systems biology is expected to advance both fundamental and applied andrology of livestock and endangered species., Competing Interests: Declaration of Competing Interest The authors of this manuscript declare that they have no conflicts of interest., (Copyright © 2024. Published by Elsevier B.V.)

Male fertility potential depends on physical, endocrine, and genetic factors responsible for producing functional male gametes. Although the main function of the male gamete, the spermatozoon, is to deliver its genetic material to the oocyte, this premise has been modified over the past few years. It is believed that the spermatozoon provides essential factors for fertilization and pre-implantation embryo development. A viable/healthy spermatozoon has functional subcellular compartments (nucleus, acrosome, midpiece, and flagellum) due to the actions of proteins, transcripts, and epigenetic marks in the organelles present in them that have important roles in reproductive biology. Male fertility potential reflects viable spermatozoa with proper function. Therefore, new approaches to functional sperm analysis are essential. Additionally, intrinsic factors and sperm molecules constitute potential biomarkers of viable spermatozoa and male fertility. Among these factors are proteins, the genome, and coding and non-coding RNAs, such as microRNAs, that act during fertilization and early embryo development. Research has been seeking increasingly efficient tools to predict fertility and functional studies of these molecules through gene and protein expression. Thus, analytical tools are essential to identify and classify viable and functional spermatozoa, to evaluate assisted reproductive male potential., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The capacity of recipients to support transferred embryos is a challenge for dairy cattle production systems. This review explores methods for increasing P4 to improve early pregnancy establishment in dairy cattle. A key aspect of P4 supplementation during the critical first weeks of pregnancy is its correlation with successful embryo elongation. Moreover, P4 was correlated to an increased chance of embryo survival after maternal recognition of pregnancy. Internal releasing devices increase circulating P4 concentrations but may negatively impact fertility possibly due to unwanted health pathologies such as vaginitis and the still undefined mechanism of haste luteolysis. The accessory corpus luteum (CL) induction in recipient dairy cattle increases endogenous P4 output increasing circulating P4 concentrations. Two ovulatory inducers are commonly used: gonadotropin-releasing hormone (GnRH) and human chorionic gonadotropin (hCG). Despite their distinct structures, GnRH and hCG are equally capable of inducing ovulation in cattle. The P4 supplementation by an accessory CL formation was widely used in fixed-time artificial insemination breeding programs, but still not exhaustively studied in embryo transfer (ET) programs. The induction of an accessory CL in ET programs has yielded inconsistent results depending on parity, embryo type production, embryo stage of development, and type of hormone used. Although maternal physiological mechanisms support the idea of increasing P4 for higher fertility and better embryo development, the actual results in creating a high-P4 maternal environment are still uncertain., Competing Interests: Declaration of Competing Interest None., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In livestock breeding, offspring of a particular sex are often favoured. Various biological mechanisms influence the offspring sex ratio (OSR). It has been hypothesised that maternal body condition/nutritional status influence OSR. We analysed the relationship between the nutritional status of the cow and OSR. The analysed dataset contained 40,913 milk recordings of 39,192 cows from 3625 farms. Nutritional status was estimated based on the fat-to-protein (F:P) ratio and urea content in milk in the seven to fourteen days prior to conception. Somatic cell count (SCC) was also considered. Cows with > 150,000 SSC were analysed separately. When SSC was normal (≤150,000), high urea with high F:P resulted in a higher probability of male offspring (61 %), with OSR significantly deviating towards male (1.47). Conversely, a high urea level and low F:P resulted in a higher probability of female offspring (57 %), with OSR significantly in favour of females (0.79). At normal or low milk urea, the sex of the offspring did not change within F:P classes. The sex ratio did not deviate from 1:1 when F:P and urea were in the normal range. When SCC was high, the probability of particular sex did not change significantly in either combination of F:P and urea, but OSR showed a tendency toward males (OSR>1) when F:P and urea were low or normal. Our results confirmed the influence of maternal nutritional status on the offspring sex. Thus, adjusting nutrition in the pre-insemination period seems to be a way to influence the sex ratio of offspring in dairy cows., Competing Interests: Declaration of Competing Interest We wish to draw the attention of the Editor to the following facts which may be considered as potential conflicts of interest and to significant financial contributions to this work. [OR] We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us. We confirm that we have given due consideration to the protection of intellectual property associated with this work and that there are no impediments to publication, including the timing of publication, with respect to intellectual property. In so doing we confirm that we have followed the regulations of our institutions concerning intellectual property. We further confirm that any aspect of the work covered in this manuscript that has involved either experimental animals or human patients has been conducted with the ethical approval of all relevant bodies and that such approvals are acknowledged within the manuscript. We understand that the Corresponding Author is the sole contact for the Editorial process (including Editorial Manager and direct communications with the office). He/she is responsible for communicating with the other authors about progress, submissions of revisions and final approval of proofs., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Enhancing reproductive performance is a key strategy to mitigate involuntary culling rates, thereby extending productive life (PL) and ultimately improving profitability in dairy cattle herds. A piecewise Weibull proportional hazards model was used to investigate the effect of several important reproductive traits on PL in Holstein dairy cows. Data comprised 200,747 lactation records from 82,505 cows sired by 1952 bulls across 36 dairy herds. PL was defined as the number of days from the first calving to the last milk record or censoring. The statistical model accounted for the time-dependent fixed effects of changes in herd size, year-season, milk production, fat and protein contents, and the time-independent fixed effect of age at first calving. Herd-year and sire effects were also included as random effects. Reproductive traits include calving traits such as calving ease (CE), calf size (CZ), and calf survival (CS), as well as female fertility traits such as number of inseminations per conception (NI), days from calving to first service (CFS), days from first service to conception (FSC), and days open (DO). All reproductive traits had a significant effect on PL (p < 0.001). Each reproductive trait was analysed separately. The relative risk (RR) of being culled increased as the severity of calving difficulties increased in both primiparous and multiparous cows. Cows that calved small or large calves showed a higher risk of being culled compared with those that calved medium size calves. The increased RR of culling was observed only for primiparous cows that gave birth to dead calves. In addition, cows that required more NI, a longer CFS, FSC, and DO had shorter longevity. These insights can deepen our comprehension of the factors affecting PL and provide information for refining management and breeding strategies, which could lead to increased profitability and sustainability in Iranian dairy farming., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

The objective was to evaluate the effect of maternal exposure to heat stress conditions at different stages of pregnancy on the reproductive performance and antral follicle count of progeny. The study was conducted at five commercial dairy farms located in southeastern Brazil. Retrospective data (2002 and 2015) on reproductive indices of daughters of Holstein cows that were exposed to heat stress conditions in the first (n = 447), second (n = 729) or third (n = 746) trimester of pregnancy and daughters of cows not exposed to heat stress (n = 359) were analyzed. Antral follicle count (AFC) and ovarian size were determined in a subgroup of animals (n = 242) by transrectal ultrasound. Statistical analysis was performed using the SAS GLIMMIX procedure. The number of services after first calving was lower in daughters of cows not exposed to heat stress conditions than in those exposed during different trimesters of pregnancy (P = 0.03). The calving interval was longer for daughters of cows exposed to heat stress conditions in the second and third trimesters of pregnancy than for those not exposed to heat stress (P = 0.01). In addition, the probability of pregnancy at first AI, (P = 0.01) and the AFC (P = 0.001) were greater in daughters of cows not exposed to heat stress conditions than in those exposed during the different phases of the gestational period. These findings indicate that maternal heat stress in different stages of pregnancy negatively affect the future fertility and AFC of bovine offspring., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Skeletal muscle is vital in maintaining metabolic homeostasis and adapting to the physiological needs of pregnancy and lactation. Despite advancements in understanding metabolic changes in dairy cows around calving and early lactation, there are still gaps in our knowledge, especially concerning muscle metabolism and the changes associated with drying off. This study aimed to characterize the skeletal muscle metabolome in the context of the dietary and metabolic changes occurring during the transition from the cessation of lactation to the resumption of lactation in dairy cows. Twelve Holstein dairy cows housed in tiestalls were dried off 6 wk before the expected calving date. Cows were individually fed ad libitum TMR composed of grass silage, corn silage, and concentrate during lactation and of corn silage, barley straw, and concentrate during the dry period. The metabolome was characterized in skeletal muscle samples (M. longissimus dorsi) collected on wk -7 (9 d before dry-off), -5 (6 d after dry-off), and wk -1, and wk 1 relative to calving. The targeted metabolomics approach was conducted using the MxP Quant 500 kit (Biocrates Life Sciences AG) with liquid chromatography, flow injection, and electrospray ionization triple quadrupole mass spectrometry. Statistical analysis on the muscle metabolite data was performed using MetaboAnalyst 5.0, which allowed us to conduct various multivariate analyses such as principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), informative heat map generation, and hierarchical clustering. The statistical analysis revealed a clear separation between pregnancy (wk -7, -5, and -1) and postcalving (wk 1). Starting 5 wk before calving and continuing through the first week thereafter, the concentration of 3-methylhistidine (3-MH) in the muscle increased. This coincided with an increase in the concentrations of 11 AA (Phe, His, Tyr, Trp, Arg, Asn, Leu, Ile, Gly, Ser, and Thr) in the first week after calving, whereas Gln decreased. l-Arginine pathway metabolites (homoarginine, ornithine, citrulline, and asymmetric dimethylarginine), betaine, and sarcosine followed a similar pattern, increasing from wk -7 to -5, but decreasing from wk -1 to 1. The transition from pregnancy to lactation was associated with an increase in concentrations of the long-chain acylcarnitine species C16, C16:1, C18, and C18:1 in the muscle, whereas the concentrations of phosphatidylcholine and sphingomyelin in the muscle remained stable. The significant changes observed in the metabolome mainly concerned the AA and AA-related metabolites, indicating muscle protein breakdown in the first week after calving. The metabolites produced by the l-Arg pathway might contribute to regulating skeletal muscle mass and function in periparturient dairy cows. The elevated concentrations of long-chain acylcarnitine species in the muscle in the first week after calving suggest incomplete fatty acid oxidation, likely due to insufficient metabolic adaptation in response to the fatty acid load around the time of calving., (Copyright © 2025 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The aim was to estimate the relative contribution of imprinting effects from both paternal and maternal sides to phenotypic variation in milk production traits including 305 days milk yield (MY), average daily milk production (ADM), fat percentage (F%), protein percentage (P%), 305 days fat yield (FY), 305 days protein yield (PY), ratio of fat percentage to protein percentage (F:P) and somatic cell score (SCS) in Iranian Holstein cows. To do this, each trait was analysed with a series of four animal models, which were identical for fixed and additive genetic effects but differed for combinations of paternal and maternal imprinting effects. The log-likelihood ratio test (LRT) and Akaike's information criteria (AIC) were used to select the best model for each trait. Correlations between traits due to additive and imprinting effects were estimated by bivariate analyses. For all traits studied, fitting the imprinting effect led to a better data fit. Also, it resulted in a noticeable decrease in additive genetic variance from 8% (SCS) to 28% (F:P). A significant maternal imprinting effect was detected on all traits studied. Estimates of maternal imprinting heritability ( h mi 2 ) were 0.07 ± 0.02, 0.04 ± 0.01, 0.06 ± 0.01, 0.05 ± 0.01, 0.5 ± 0.01, 0.09 ± 0.02, 0.07 ± 0.02 and 0.06 ± 0.01 for MY, ADM, F%, P%, FY, PY, F:P and SCS, respectively. For F:P, in addition to the maternal imprinting effect, a significant paternal imprinting component was also detected with a 7% contribution to phenotypic variance of F:P. Estimates of direct heritability ( h a 2 ) were 0.29 ± 0.02, 0.17 ± 0.01, 0.22 ± 0.02, 0.11 ± 0.01, 0.18 ± 0.02, 0.22 ± 0.02, 0.15 ± 0.04 and 0.06 ± 0.01 for MY, ADM, F%, P%, FY, PY, F:P and SCS, respectively. Maternal imprinting correlations (r mi ) were in a wide range between -0.75 ± 0.15 (P%-SCS) and 0.95 ± 0.11 (MY-ADM). Additive genetic correlations (r a ) ranged between -0.54 ± 0.05 (MY-P%) and 0.99 ± 0.01 (MY-ADM) and phenotypic correlations (r p ) ranged from -0.30 ± 0.01 (MY-F%) to 0.93 ± 0.01 (MY-ADM). The Spearman's correlation between additive breeding values including and excluding imprinting effects deviated from unity especially for top-ranked animals implying re-ranking of top animals following the inclusion of imprinting effects in the model. Since including imprinting effects in the model resulted in better data fit and re-ranking of top animals, including these effects in the genetic evaluation models for milk production traits was recommended., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Background: There are no studies belong NOTCH2 gene polymorphism in relation to reproductive and productive traits in Holstein cattle. The objective of the present study was to investigate the effect of NOTCH2 gene polymorphisms on productive and reproductive performance of fertile and anestrum cattle., Methods: The cattle were classified into anestrus for 3-12 months postpartum (n = 115, 37.7%) and normal cyclic fertile (n = 190, 62.3%). Age at 1st calving, calving interval, calf birth weight, milk yield and days of milking data were obtained from the farm records for all animals. Blood samples were collected from fertile and anestrum animals for DNA extraction and the PCR as well as single-strand conformation polymorphism techniques (SSCP) were performed for detection of the NOTCH2 gene polymorphism., Results: The sequencing results showed that NOTCH2 gene in cattle is polymorphic with 5 genotypes AA, AG, GG, CC and CT. Four novel SNPs as transition single base substitution mutations were detected at 3: 23,192,033 (A/G), 3:23192149 (C/T), 3:23192071 (C/T) and 3:23192143 (G/A). GG genotype of NOTCH2 gene was associated with shorter calving interval and heavier calf birth weight in both fertile and anestrum cattle., Conclusions: NOTCH2 gene in cattle could be used as a genetic marker involved in reproductive traits in both fertile and anestrum cattle., Competing Interests: Declarations. Ethics approval and consent to participate: All animal management and sampling procedures were carried out under the direction of the Medical Research Ethics Committee (MREC) of National Research Centre with approval number 07110723. All methods were carried out in accordance with relevant guidelines. We used the animals and their data in the study after the acceptance of the farm supervisors who participated in the research. Consent to participate: Not applicable. Consent for publication: Not applicable. Conflict of interest: No conflict of interest exists. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

In the present study 1,709 cattle, including 1,118 Drakensberger (DRB), 377 Nguni (NGI), and 214 Tuli (TUL), were genotyped using the GeneSeek® Genomic Profiler™ 150 K bovine SNP panel. A genomic data set of 122,632 quality-filtered single nucleotide polymorphisms (SNPs) were used to identify selection signatures within breeds based on conserved runs of homozygosity (ROH) and heterozygosity (ROHet) estimated with the detectRUNS R package. The mean number of ROH per animal varied across breeds ranging from 36.09 ± 12.82 (NGI) to 51.82 ± 21.01 (DRB), and the mean ROH length per breed ranged between 2.31 Mb (NGI) and 3.90 Mb (DRB). The smallest length categories i.e., ROH < 4 Mb were most frequent, indicating historic inbreeding effects for all breeds. The ROH based inbreeding coefficients (F ROH ) ranged between 0.033 ± 0.024 (NGI) and 0.081 ± 0.046 (DRB). Genes mapped to candidate regions were associated with immunity (ADAMTS12, LY96, WDPCP) and adaptation (FKBP4, CBFA2T3, TUBB3) in cattle and genes previously only reported for immunity in mice and human (EXOC3L1, MYO1G). The present study contributes to the understanding of the genetic mechanisms of adaptation, providing information for potential molecular application in genetic evaluation and selection programs., Competing Interests: Declarations. Ethics approval: The genotypic data used in the current study was provided by SA Stud Book with consent from the Drakensberger, Nguni, and Tuli Cattle Breeders' Society of South Africa. The study was approved by the Ethics Committee in the Faculty of Natural and Agricultural Sciences at the University of Pretoria (NAS235/2022). Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s).)

In cattle, oviductal function is controlled by the ovarian sex-steroids estradiol and progesterone. Here, we tested the hypothesis that the exposure to contrasting sex-steroid milieus differentially impacts the oviductal fluid composition. Estrous cycles of non-lactating, multiparous Nelore cows were pre-synchronized and then synchronized with a protocol designed two induce ovulation of large or small follciles. Larger preovulatory follicle (day 0) and corpora lutea (day 4) and greater estradiol (day 0) and progesterone (day 4) concentrations were observed in the large follciles group. Four days after induced ovulation, oviductal fluid was collected post-mortem. Quantitative mass spectrometry was used to determine the concentration of amino acids, biogenic amines, acylcarnitines, phosphatidylcholines, lysophosphatidylcholines, sphingomyelins, hexoses, prostaglandins, and related compounds. Multivariate analyses (orthogonal projections to latent structures discriminant analysis) were conducted to compare the metabolomic signatures of oviductal fluids. Correlation network analysis was conducted to measure the strength and hierarchy of associations among metabolites. Of the 205 metabolites quantified, 171 were detected in at least 50% of the samples and were included in further data analysis. After orthogonal projections to latent structures discriminant analysis analysis, samples of the large follciles and small follciles were divided clearly into two non-overlapping clusters. Twenty metabolites had different or tended to have different concentrations in the oviductal fluid when comparing groups. Seven of these 20 analytes had greater concentrations in large follciles cows. Moreover, total sum of biogenic amines, phosphatidylcholines, and prostaglandins were higher in the small follciles group. The correlation network showed that the large follciles group metabolites' concentrations were highly intercorrelated, which was not observed in the small follciles group. We concluded that the periovulatory endocrine milieu regulates the composition of the oviductal fluid., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Reproductive outcomes were evaluated in Nelore (Bos indicus) heifers submitted to one, two or no ovulation induction protocols based on progesterone (P4) and estradiol (E2) prior to a timed-artificial insemination (TAI) protocol. A total of 1,437 heifers (13.0 ± 0.8 mo old; 3.1 ± 0.1 of body condition score [BCS] and 279.9 ± 25.8 kg of body weight [BW]) were randomly assigned to 1 of 3 treatments: 0IND (n = 486): no ovulation induction protocol; 1IND (n = 481): one ovulation induction protocol; or 2IND (n = 470): two ovulation induction protocols. On Day -47, heifers from 2IND received a disinfected intravaginal P4 device (2 g, previously used for 21 d), kept until Day -40, when 0.5 mg of E2 cypionate (EC) was given. On Day -19, heifers from 2IND and 1IND underwent the same protocol. On Day 0, all heifers were submitted to the same TAI protocol, starting with a P4 device (0.5 g), 0.5 mg of cloprostenol sodium (PGF), and 1.5 mg of E2 benzoate. On Day 7, P4 device was removed, 0.5 mg of PGF, 0.5 mg of EC, and 200 IU of equine chorionic gonadotropin (eCG) were administered. The TAI was performed 2 d later (Day 9). Blood samples were collected on Days -47 and 0, to determine the presence of CL (circulating P4 concentrations ≥ 1.0 ng/mL). Ultrasound was performed on Days 40, 75 and between Day 150 and parturition to assess pregnancy per AI (P/AI) and pregnancy loss (PL). Statistical analyses were performed using SAS 9.4 ( a-c P ≤ 0.05; A,B 0.05 < P ≤ 0.10). The proportion of heifers with CL on Day -47 was similar among groups (3.4%). A greater proportion of heifers from 1IND had CL on Day 0, followed by 2IND, then 0IND (87.9 a ; 80.4 b ; 28.8 c %). There was an effect of treatment on expression of estrus (2IND: 66.6 a ; 1IND: 67.2 a ; 0IND: 57.4 b %), P/AI on Day 40 (2IND: 53.4 a ; 1IND: 43.9 b ; 0IND: 46.5 b %), P/AI on Day 75 (2IND: 49.8 a ; 1IND: 40.5 b ; 0IND: 44.4 ab %) and final P/AI (2IND: 45.5 a ; 1IND: 35.8 b ; 0IND: 40.5 ab %). No differences were observed in PL (40-75 = 6.3%; 75-final = 9.6%; Total = 15.3%). Particularly within lighter heifers, there was an effect of treatment on P/AI on Day 40 (0IND: 39.2 b ; 1IND: 43.3 ab ; 2IND: 53.9 a %) and on Day 75 (0IND: 36.6 B ; 1IND: 39.0 AB ; 2IND: 48.5 A %). At the first pregnancy diagnosis, more nonpregnant heifers from 2IND had CL on Day 40 than 0IND, but 1IND did not differ from the other groups (85.4 a ; 74.8 b ; 80.8 ab %). In conclusion, ovulation induction protocols performed prior to the TAI protocol increased the proportion of heifers with CL on Day 0. The use of two induction protocols resulted in greater fertility, particularly in lighter heifers, and increased cyclicity among nonpregnant heifers. These results indicate that this strategy may be an optimized method for inducing cyclicity and enhancing fertility of prepubertal Nelore heifers raised in pasture-based feeding systems., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Subtle changes in behaviour, which may be useful as early indicators of disease or stress in farm animals, can be detected using precision livestock technologies. However, as animals often display differences in their baseline behaviours from one another, individual variation needs to be measured and accounted for if we want to successfully detect abnormalities. In addition to consistent individual differences in their mean behaviour, which are called behavioural types and measured by repeatability, animals may differ in the amount of day-to-day variation around their own mean. This is known as predictability and it is very rarely measured in animals as it requires data with high granularity for extended periods of time, which is hard to obtain without precision technologies. Here we aim to quantify the repeatability and predictability of lying and feeding, two behaviours which have been investigated as potential indicators of disease with inconsistent results, in dairy cows. We used data on daily lying behaviours from leg-mounted sensors for 1439 cows and data on daily feeding behaviours from neck-mounted sensors for 2584 cows belonging to multiple herds to quantify the variation between individuals, the individual differences in predictability and any correlations between individual behaviour type and predictability of the same behaviour. Using multivariate double hierarchical generalised linear models, we were able to quantify individual variation in feeding and lying behaviours of adult cows for the first time. Consistent variation between individuals was present for all measures of lying and feeding with repeatability values of 0.38 for daily feeding time and 0.34 for daily lying time. Individuals also varied in their levels of predictability with coefficients of 0.46 and 0.29 for the daily lying and feeding time respectively. Lastly, there were significant positive correlations between several behaviours and the amount of residual intra-individual variation for the same behaviour (mean lying bout length: 0.93, mean feeding bout length: 0.88), indicating that cows with the longest bouts of the two behaviours were also more variable and unpredictable, perhaps due to an opportunistic strategy. These results highlight the importance of measuring individual variation in behaviour, supporting the evidence of personality traits in cattle, as well as differences in predictability, which must be taken into account in any use of behavioural indicators for early disease diagnosis., Competing Interests: Declaration of Competing Interest None, (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The aim was to evaluate the efficiency of two different ultrasonographic systems, Doppler mode vs. Two-dimensional mode (B mode), to identify the pregnancy status of beef cows and heifers on day 21 (D21) after Timed Artificial Insemination (TAI). The experiment was performed on a commercial beef farm in central-west region of Brazil using 1895 Nelore heifers and cows. All females had ovulation synchronized for a TAI that was performed on D0. Twenty-one days after the TAI, all animals had their ovaries evaluated by ultrasound for pregnancy diagnosis based on the size of the corpus luteum (CL). Using B mode ultrasonography, females without a CL or with a CL ≤ 10 mm in diameter were considered nonpregnant, whereas females with a CL > 10 mm in diameter were considered potentially pregnant. After the B mode examination, the Doppler mode was turned on, and the CL was evaluated by the subjective percentage of blood perfusion in the total area of the CL. Using Doppler mode, females were considered nonpregnant if they had no CL or the CL had ≤25 % of the total area with detectable blood perfusion, whereas animals with >25 % blood perfusion in the CL were considered potentially pregnant. The results for each method (potentially pregnant or nonpregnant) were later compared with the gold standard technique, which was a pregnancy diagnosis on D33 after TAI using ultrasound with visualization of an embryonic heartbeat. The accuracy was determined using the 2 × 2 contingency table approach. The area under the curve using the receiver operating characteristic curve for Doppler mode and B mode were 0.929 and 0.902 (P < 0.01), respectively. There were almost no false negatives (designated non-pregnant but later pregnant at D33) with either technique (0.2 % vs. 0.3 %; P = 0.65 for Doppler mode vs. B mode, respectively). False positives (designated pregnant but non-pregnant on D33) were greater for B mode compared to Doppler (19.1 % vs. 14.0 %; P < 0.01). This resulted in Doppler mode having similar high values as B mode for Negative Predictive Value (99.9 vs. 99.6 %; P = 0.85) and Sensitivity (99.8 vs. 99.7 %; P = 0.86) but there were differences in Specificity (86 vs. 80.9 %; P < 0.01), Positive Predictive Value (88 vs. 84.3 %; P < 0.01), and Accuracy (93.0 vs. 90.4 %; P < 0.01). In conclusion, evaluation of CL blood perfusion by Doppler produced greater accuracy in the early identification of nonpregnant heifers and cows on D21 after TAI than measurement of CL diameter with B mode ultrasound; although both had over 90 % accuracy in identifying pregnant and nonpregnant females., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Climate change is a major concern for the near future and for livestock breeding. Cattle breeding, due to its greenhouse gas emissions, is one of the most implicated industries. Consequently, the main future goals are to breed animals resilient to climate change, with the aim of lowering the livestock impact on the environment and selecting animals that will be able to resist different, unsuitable, and changing climates. The aim of this literature review is to compare the most recent studies on the response and adaptation of beef cattle breeds to extreme environments, in terms of genes and pathways involved. Beef breeding is just starting to implement genomics in its selection plans, and shedding light on the genomic responses to extreme climates could speed up and simplify the adaptation of these breeds to climate change. This review discusses the genes involved in climatic stress responses, including those related to extremely cold climates, in beef and dual-purpose cattle breeds. Genes were associated with productive traits, coat and skin structure and development, thermotolerance, cellular physiology and DNA repair mechanisms, immune system, and fertility traits. The knowledge of genes and pathways involved in climate resilience should be taken into consideration for further selection in beef cattle breeding and could promote the valorization of local breeds adapted to extreme environmental conditions. The use of local or resilient breeds could enhance the environmental and social sustainability, animal welfare, and production, compared with the introduction of cosmopolitan breeds with uncertain adaptation in uncontrolled environmental areas., (© 2024 The Author(s). Animal Genetics published by John Wiley & Sons Ltd on behalf of Stichting International Foundation for Animal Genetics.)

We offer a perspective on the major challenges that are confronting the management of reproduction in sheep and cattle in Australia and New Zealand, over the next two decades. An important context is the dominance of grazing systems in which large flocks or herds are managed over large areas where it is challenging to manage reproduction with precision. Consequently, the variable forage supply usually dominates reproductive outcomes, a problem that will be exacerbated by global heating. Thus, in extensive grazing systems, there is a great need for technological solutions to improve the management of nutrition. Global heating will also exert direct effects on reproductive function. Therefore, for the foreseeable future, reproduction will remain a focus for industry. In addition, as the industries develop, we foresee continued societal pressure to reduce medication, mitigate environmental damage, and improve animal well-being. Management solutions for extensive grazing systems must involve minimal interventions with the animals and be applicable to diverse genotypes and environments. Clearly, genetics and breeding will be at the heart of solutions and elegant strategies will be needed that focus on developing animals that are robust, if perhaps a little less productive. A high rate of genetic gain is the main reason for pursuing reproductive technologies, but highly advanced reproductive technology is not likely to be the best fit in extensive management systems. Even for AI, the simplest technology, uptake is limited and lateral thinking is needed to find ways to improve the rates of genetic gain. We conclude that there are many opportunities for improving reproductive performance in sheep and cattle in Australia and New Zealand. As we gain deeper understanding of the processes involved, we should be able to make progress in fertility and fecundity, embryo survival, and postnatal survival. Improvements in reproductive performance will increase productivity, and should also be associated with significantly improved animal well-being and a reduction in methane emissions intensity. To capture these benefits, the development of new management options will require lateral thinking about reproductive technology for extensive grazing systems, and a transdisciplinary approach that brings together the systems biology of grazing animals with an understanding of the barriers to adoption by farmers., Competing Interests: Declaration of competing interest The authors declare that the research described herein was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024. Published by Elsevier Inc.)

The objective of this study was to evaluate which biochemical markers in the prepartum period of dairy cows influence the immediate postpartum period, the quality of colostrum, and the passive immunity transference in the calves. The experiment was performed on a commercial dairy farm with 52 pregnant multiparous Holstein cows. Animals that gave birth to twins or males were discarded from the experiment. On days -20 of the expected calving date and 24 hours after calving, blood collections, body condition score assessments, and animals weighing were performed. Blood samples from calves were performed 24 hours after colostrum intake. Calf plasma was used to estimate the passive immunity transfer by % brix and total plasma proteins (TPP). In the principal component analysis, it was shown that postpartum NEFA and BHBA was higher in cows with higher prepartum urinary pH and Ca lower prepartum. The cows with the highest NEFA and BHBA in pre and postpartum were the ones that had the lowest % brix in the colostrum. The % brix of the cow's colostrum directly influenced the % brix and TPP of the calves. The NEFA in the cows prepartum negatively influenced the markers of immunity, the higher the NEFA, the lower the % brix of the cows' colostrum, % brix of the calves, and TPP. In multivariate regression analyses it was shown that pre-calving NEFA was the marker that most influenced post-calving cow markers and calf % brix, along with colostrum time and % brix of the colostrum (P= 0.0092; r 2 = 0.83). Cows with higher values NEFA in the prepartum had lower calcemic in the immediate postpartum period. Prepartum NEFA was the marker that most influenced the cows' immediate postpartum period, being directly related to Ca serum, and also to the passive immunity transference., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The present study was undertaken to determine the effect of heat stress on milk production (test day milk yield) and compositional traits (fat%, protein%, fat yield, protein yield) as well as to observe the pattern of response to increasing heat load on these traits in Jersey crossbred cows, maintained at ICAR-National Dairy Research Institute, Eastern Regional Station, Kalyani, West Bengal, India. The weather information, obtained from the NASA POWER database based on the location of the farm latitude and longitude, was used to calculate the Temperature Humidity Index (THI). To analyze the data, a linear model was fitted to the milk production and compositional records, which were adjusted for additive genetic effect of animal, permanent environmental effect of animals and known environmental sources of variations. Subsequently, a segmented linear regression model was fitted, and the least squares estimates of production and composition traits in different classes of THI were used as the dependent variable. Two THI break-points (BP) for milk yield and one THI BP for fat yield, protein %, and protein yield were found. The first and second BP for milk yield was at THI 59 and 77, respectively, with a significant decline in milk yield of -0.04 kg/unit of THI at second BP. The BP for fat and protein yield was at THI 76, with a decline rate of -1.18 and - 0.61 g/unit of THI increase, respectively. The findings revealed the significant adverse effects of THI on milk production and composition traits in Jersey crossbred cattle., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: The authors consent that this manuscript and all associated data should be published. Competing interests: The authors declare no conflicts of interest., (© 2024. The Author(s) under exclusive licence to International Society of Biometeorology.)

Milk lipolysis is defined as the hydrolysis of triglycerides, the major component of milk fat, resulting in the release of short-chain fatty acids (FA), which are responsible for rancid flavor, and partial glycerides, which impair functional properties such as foaming and creaming abilities. Milk lipolysis is a complex phenomenon that depends on both animal parameters and breeding factors. Milk spontaneous lipolysis is known to be higher in milk from evening milkings than that from morning milkings. This may be related to the longer length of overnight milking intervals or to the nycthemeral cycle. In this experiment, our objective was to study the impact of both milking intervals and time of day on milk spontaneous lipolysis in twice-daily milking systems with 1 of 3 milking intervals: short day and long night (SD-LN; 6:30 a.m. and 4:30 p.m.); long day and short night (LD-SN; 6:30 a.m. and 8:30 p.m.); and balanced day and night (BDN; 6:30 a.m. and 6:30 p.m.). To achieve this goal, 21 multiparous dairy cows in mid-lactation were used in a 3 × 3 Latin square design over 3 periods. The experiment lasted 5 wk, corresponding to 3 experimental periods of 6 d alternating with 8 d of milking with conventional hours (morning-evening gap of 10 h). We confirmed that milk spontaneous lipolysis was influenced by milking interval, but not milking time. Indeed, we observed more lipolysis in SD-LN evening milk (+0.20 mEq/100 g fat) and LD-SN morning milk (+0.22 mEq/100 g fat), both of which corresponded to a 10-h interval between successive milkings. High-lipolysis milk came from cows that produced less milk with a higher milk fat content. No significant difference between milkings was observed for BDN. Milk protein, total P, and citrate contents increased according to the duration of mammary gland storage of milk (from 10 to 14 h). We found no effect of milking intervals on milk fat globule diameter. The milk Na + /K + ratio, indicating an opening of tight junctions in the mammary gland, increased only in evening milkings with BDN and LD-SN. Overall, we found that the effect of milking intervals on lipolysis is stronger than that of the nycthemeral cycle., (© 2024, The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Modern livestock production systems are characterized by a greater focus on intensification, involving managing larger numbers of animals to achieve higher productive efficiency and animal health and welfare within herds. Therefore, animal breeding programs need to be strategically designed to select animals that can effectively enhance production performance and animal welfare across a range of environmental conditions. Thus, this review summarizes the main methodologies used for assessing the levels of genotype-by-environment interaction (G × E) in cattle populations. In addition, we explored the importance of integrating genomic and phenotypic information to quantify and account for G × E in breeding programs. An overview of the structure of cattle breeding programs is provided to give insights into the potential outcomes and challenges faced when considering G × E to optimize genetic gains in breeding programs. The role of nutrigenomics and its impact on gene expression related to metabolism in cattle are also discussed, along with an examination of current research findings and their potential implications for future research and practical applications. Out of the 116 studies examined, 60 and 56 focused on beef and dairy cattle, respectively. A total of 83.62% of these studies reported genetic correlations across environmental gradients below 0.80, indicating the presence of G × E. For beef cattle, 69.33%, 24%, 2.67%, 2.67%, and 1.33% of the studies evaluated growth, reproduction, carcass and meat quality, survival, and feed efficiency traits, respectively. By contrast, G × E research in dairy cattle populations predominantly focused on milk yield and milk composition (79.36% of the studies), followed by reproduction and fertility (19.05%), and survival (1.59%) traits. The importance of G × E becomes particularly evident when considering complex traits such as heat tolerance, disease resistance, reproductive performance, and feed efficiency, as highlighted in this review. Genomic models provide a valuable avenue for studying these traits in greater depth, allowing for the identification of candidate genes and metabolic pathways associated with animal fitness, adaptation, and environmental efficiency. Nutrigenetics and nutrigenomics are emerging fields that require extensive investigation to maximize our understanding of gene-nutrient interactions. By studying various transcription factors, we can potentially improve animal metabolism, improving performance, health, and quality of products such as meat and milk., (© 2024 The Author(s). Animal Genetics published by John Wiley & Sons Ltd on behalf of Stichting International Foundation for Animal Genetics.)

The bovine major histocompatibility complex (MHC), also known as the bovine leukocyte antigen (BoLA) complex, is the genomic region that encodes the most important molecules for antigen presentation to initiate immune responses. The first evidence of MHC in bovines pointed to a locus containing 2 antigens, one detected by cytotoxic antiserum (MHC class I) and another studied by mixed lymphocyte culture tests (MHC class II). The most studied gene in the BoLA region is the highly polymorphic BoLA-DRB3, which encodes a β chain with a peptide groove domain involved in antigen presentation for T cells that will develop and co-stimulate cellular and humoral effector responses. The BoLA-DRB3 alleles have been associated with outcomes in infectious diseases such as mastitis, trypanosomiasis, and tick loads, and with production traits. To catalog these alleles, 2 nomenclature methods were proposed, and the current use of both systems makes it difficult to list, comprehend and apply these data effectively. In this review we have organized the knowledge available in all of the reports on the frequencies of BoLA-DRB3 alleles. It covers information from studies made in at least 26 countries on more than 30 breeds; studies are lacking in countries that are important producers of cattle livestock. We highlight practical applications of BoLA studies for identification of markers associated with resistance to infectious and parasitic diseases, increased production traits and T cell epitope mapping, in addition to genetic diversity and conservation studies of commercial and Creole and locally adapted breeds. Finally, we provide support for the need of studies to discover new BoLA alleles and uncover unknown roles of this locus in production traits., (© 2024, The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

This study aimed to investigate the differences between productive and reproductive performance traits of sexually precocious and non-sexually precocious Nellore heifers and to evaluate the genetic correlation of sexual precocity with traits of economic importance. For this purpose, 300,000 Nellore heifers were evaluated for reproductive traits: heifer pregnancy (HP) at 14 (HP 14 ), 18 (HP 18 ), and 24 (HP 24 ) months; heifer rebreeding (HR); number of progenies up to 53 months (NP 53 ); and probability of the cow remaining in the herd until 76 months with at least 3 progenies (Stay). The growth-related traits evaluated included female yearling weight (YW); average daily gain from weaning to yearling (ADG W-Y ); weight at maturity (MW); weaning weight of first progeny (WW prog ); and female visual scores at yearling for conformation (Conf), precocity (Prec) and muscling (Musc). The effects of female YW and ADG W-Y in six categories on HP 14 , HP 18 , and HP 24 were analyzed using Generalized linear mixed models (GLMM). Furthermore, a linear mixed model was used to evaluate the impact of HP on WW prog , MW, and reproductive performance (NP 53 and Stay). Genetic correlations of HP evaluated in different months with growth and reproductive traits were estimated using a bivariate animal model. Precocious heifers (HP 14 ) were lighter for YW and MW but had greater ADG W-Y than HP 18 and HP 24 . The probability for HP 14 , HP 18 , and HP 24 increased as the classes of YW and ADG W-Y increased. However, heifers weighing more than 326 kg had a slight reduction in the probability of becoming pregnant at HP 14 and HP 18 . Precocious heifers (HP 14 and HP 18 ) produced their first progeny by 3 % lighter than HP 24 , although they had a greater NP 53 . Precocious heifers at 18 months (HP 18 ) were 3 % and 6.8 % more likely to remain in the herd than HP 14 and HP 24 heifers, respectively. Genetic correlations between growth traits (WW, YW, ADG W-Y, and MW) and heifer pregnancy (HP 14 , HP 18 , and HP 24 ) ranged from weak (r g  = 0.27 ± 0.05) to moderate (r g  = -0.47 ± 0.07). The genetic correlation between HR and HP was stronger for HP 24 (0.75) against HP 14 (0.58) and HP 18 (0.64). Although, the genetic correlation between NP 53 and Stay with HP 14 was higher (r g  = 0.53 and 0.45) than those observed for HP 18 (r g  = 0.46 and 0.38) and HP 24 (r g  = 0.35 and 0.39). The genetic correlation estimates between HP and visual scores were moderate and favorable for HP 14 . Selecting HP 14 is beneficial for production systems because it increases the NP 53 during the productive life without compromising heifer productivity or reproductive performance. However, attention should be given to improving the HR of heifers who become pregnant early., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Body condition dynamics are known to affect the different steps of reproduction in cattle (cyclicity, estrus expression, fertilization, embryo development). This has led to a widespread idea that there is an ideal-target optimal body condition, but no clear profile has yet been identified. Here we investigated the relationships between BCS profiles and reproductive performance in dairy cows. Data were from Holstein or Normande herds in 6 French experimental farms. In the Holstein breed, we discriminated 4 BCS profiles based on combining BCS at calving (Low indicates BCS ∼2.6 points at calving; High indicates BCS ∼3.3 points at calving) with BCS loss after calving (Moderate [M] indicates BCS loss of ≤1.0 points at calving; Severe [S] indicates BCS loss of >1.0 points at calving). The Low-M profile mostly included multiparous cows with higher milk yield and lower reproductive performance than cows in the 3 other profiles. Low-M cows that experienced abnormal ovarian activity had lower reproductive performance than their profile-mates. Moreover, 67% of Low-M cows kept the same profile at the following lactation. The High-S profile mostly included primiparous cows with lower milk yield and higher reproductive performance than cows in other profiles. In High-S cows, higher milk yields correlated with higher risk of failure to calf on first insemination. Moreover, 38% of High-S cows kept the same profile at the following lactation, and none changed to High-M. The other 2 BCS profiles (Low-S and High-M) were intermediate in terms of milk yield and reproductive performance. In Normande, we discriminated 3 BCS profiles based on combining BCS at calving (Low: ∼2.6 points; High: ∼3.5 points) with BCS loss after calving (Flat [F]: flat with no loss; M: ∼0.5 points; or S: ∼1.0 point). The Low-M and High-S profiles included cows with similar performance, even though High-S-profile cows showed better but not significantly different milk yield and reproduction performance. The High-F profile included cows that were more likely to experience abnormal ovarian activity and fail at first insemination than cows in other profiles. More than 50% of Normande cows with 2 successive lactations kept in the same BCS profile at the next lactation. Even though a low BCS at calving combined with severe BCS loss (more than 1 point) after calving was found to increase reproductive failure, there was no evidence of an optimal BCS profile for reproduction in dairy cows, and reproductive success or failure is multifactorial., (© 2024, The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Numerous studies have shown the influence of the moon cycle on biological functions in farm animals, suggesting that predicting calving distribution could enhance survival rates by improving management practices in animal production. This study builds on previous research by examining the impact of the lunar cycle on calving frequency, gestation length, birth weight, and calf sex in artificially inseminated cows. We analyzed 121,276 records from dual-purpose crossbred cows across 36 farms along the western margin of Lake Maracaibo basin, Venezuela. The lunar cycle was divided into 30 periods of 0.984 days each and further categorized into four phases: 1) 1.97 days around the new moon; 2) 12.8 days during the crescent phase; 3) 1.97 days around the full moon; and 4) 12.8 days during the waning phase. Data were analyzed using a logistic regression and the general linear model in SAS, comparing proportions and means with contrast and general linear model tests, respectively. There was no association between the lunar cycle and the sex of calves. However, calvings distribution across the lunar month showed notable peaks 2 days around both the new and full moons, a pattern consistent regardless of the number of calvings or gestation lengths. In addition, significant differences were observed between the days surrounding the new (1) and full (3) moons compared to the other lunar phases (2 and 4). Moon cycle also influenced gestation length and calf birth weight. This study expands previous findings and demonstrates that the lunar cycle consistently affects certain reproductive traits in inseminated dual-purpose cows, including gestation length, calf birth weight, and calving distribution, with practical implications for cattle operations.

Bull fertility is a multi-factorial trait and is affected by many factors, such as nutrition, genetics, and epigenetics. Superior quality male germplasm with high genetic merit helps to improve the livestock production trait. To achieve the target of livestock production, the availability of superior male germplasm is a great concern. In developing countries, there is a gap between the highly fertile frozen semen doses produced and the highly fertile frozen semen doses required. Improving the quality of existing low-fertile semen from high genetic merit bulls seems to play a promising role in filling this gap. Seminal exosomes are extracellular vesicles secreted by the epithelial cells of the testis, epididymis, and accessory sex glands such as the prostate gland. They contain a cargo of bioactive molecules such as proteins, nucleic acids and various metabolites. These molecules are transferred to the spermatozoa during its maturation and help in sperm capacitation, maturation, acrosome reaction, and fertilisation. Studies reveal that seminal exosomes help to improve the sperm functionality of low-quality sperm. Identification of the molecular profile of exosomes of bulls with proven fertility and their addition in an extender containing low-fertile semen may help to ameliorate the sperm quality of low-fertile semen, which may eventually aid in generating quantities of highly fertile ejaculates., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Diets reliant on grazed, temperate herbage are prone to greater nitrogen (N) losses via urine than balanced stall-fed diets which poses a greater risk for N emissions. Measures for improving the N utilisation in grazing-based dairy cattle systems are predominantly investigated on homogenous clover-ryegrass pastures with high herbage yields and nutritional quality. In contrast, grazing-based systems reliant on less external inputs (e.g., synthetic fertilisers or concentrates) using semi-natural grassland as main feed source, such as in large parts of Central Europe, received less attention. The N utilisation and excretion of grazing cows in low-input dairy farms were, thus, investigated on nine commercial organic dairy farms in South Germany across one to four periods per farm. The dataset captured a diverse set of dairy production systems comprising 323 individual animal observations. A mean (± one SD) milk production, DM intake (DMI), and pasture DMI of 23.9 kg (± 5.35), 21.0 kg (± 3.21), and 11.3 kg/d (± 4.83), respectively, was determined. Feed intake was estimated using titanium dioxide and faecal CP concentration as markers of faecal excretion and diet digestibility, respectively. Milk N use efficiency (MNE; i.e., milk N secretion as share of N intake) averaged 24.7 g/100 g N intake (± 5.91), which is greater than observations in temperate, high-input grazing systems but lower than in cows receiving balanced diets in the barn. The MNE and another seven indicators of N utilisation and excretion displayed a wide range of values. The grazing management factors explaining this variation were, thus, identified via backward elimination. The supplementation strategy had the greatest potential for manipulating N utilisation and excretion of dairy cows. Increasing shares of fresh forages (i.e., meadow grass or clover-grass leys) as well as of hay in supplement DMI increased N utilisation (e.g., MNE) and decreased urinary N excretion (e.g., urinary N to creatinine ratio), while increasing shares of concentrates in supplement DMI are related to lower N losses via urine. At the same time, increases in total supplement DMI reduced N utilisation and increased urinary N excretion. Hence, full-time grazing combined with supplementation of fresh forage and hay in the barn is a viable option for low-input, grazing-based dairy operations with moderate levels of N losses., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

In Zimbabwe a lot of studies have been done on nutrition, breeding, physiology and health of farm cows but with little or no consideration of the impacts of these studies on cow welfare. As a result political importance and practical progression of cow welfare is still lagging behind in the country just like most developing countries. The aim of this study was to evaluate the welfare status of dairy cows from large scale dairy farms through an assessment of risk factors/drivers and indicators of cow welfare. For this study 728 dairy cows from all the 31 large scale dairy farms in Midlands Province, Zimbabwe, were selected for the study noting down risk factors and indicators of dairy cow welfare during both the dry and rainy season. Human avoidance distance test results revealed that 81% of the cows were touched by the approaching stockpeople, whereas 19% could not be touched, and this was significantly associated with breed of the cow (χ 2  = 115, DF = 9, P < 0.0005). From the study 95% of the cows examined were not lame (score 1) and for those that were lame only 0.6% (n = 4) had severely impaired mobility (score 5). Whereas 30% of the cows observed during the rainy season were heavily soiled with manure (score 4), only 1% of the cows observed during the dry season were heavily soiled (score 4). Cow cleanliness was significantly associated with manure accumulation in housing and handling facilities in both study 1 (χ 2  = 18, DF = 6, P = 0.006) and study 2 (χ 2  = 47, DF = 6, P < 0.001). The average body condition score of observed dairy cows from both study 1 and study 2 was fair (BC = 3) and body condition was signficantly associated with the breed of cow in both study 1 (χ 2  = 22, DF = 12, P = 0.039), and study 2 (χ 2  = 38, DF = 12, P < 0.005). Exotic breeds like the Holstein generally faired low when compared to locally adapted breeds like theAyrshire., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Podolian cattle is an autochthonous breed well adapted to the harsh semi-arid environments of the Southern Italy regions; the extensive rearing system used for these indigenous animals is based on grazing on spontaneous pastures, such as grasslands or wood pastures These grazing systems respect animal welfare and enrich animal products with characteristics closely related to the feeding system and the farming environment. The aim of the present study was to characterize the nutritional value of a forage crop and a wood-pasture and to evaluate the effects of grazing by Podolian young bulls on the performances and meat quality in relation to the age at slaughter (14 or 18 months) and to the ageing time of meat (3, 9 or 14 days). The metabolizable energy and the gas production were greater in April and June for both pasture systems. Young bulls raised on the grassland showed greater slaughter weights ( p  < 0.05) as compared to those fed on the woodland system, at both the slaughtering ages. The Warner Bratzler Shear (WBS) force values for raw and cooked meat were not influenced by the pasture system but they significantly ( p  < 0.01) decreased in relation to the ageing time in all the groups. Ageing markedly ( p  < 0.05) increased the malondialdehyde (MDA) concentration from 3 to 14 days of storage, regardless of the pasture system and the slaughtering age. The n-6/n-3 polyunsaturated fatty acid ratio of meat was markedly lower in grassland animals, regardless of the age of slaughter. In conclusion, 18 months old grassland beef showed better performances and yield of meat cuts. Ageing for 9 days positively affected meat WBS without increasing MDA concentration.