Search

Ovulation synchronization protocols are well established and are routinely used in beef livestock systems. In addition to the genetic gain provided using fixed-time artificial insemination (TAI), there is an optimization in production in bovine females that are submitted to this reproduction biotechnique. In Bos indicus cows created in extensive system, a long period of postpartum anestrus is observed due to factors inherent to the presence of the calf and the negative energy balance. Therefore, the main advantage of using hormonal treatments after calving is to anticipate the first ovulation and the return to cyclicity. However, the final response to the TAI protocol based on estrogen (E2) and progesterone (P4) is approximately 80% in suckled Bos indicus beef cows. Hormonal strategies, such as the use of P4 and energy/protein supplementation prior to the TAI protocol, are used to increase the reproductive efficiency of these females. Furthermore, the correct time to start the TAI protocol after calving to optimize productivity and the duration of exposure to P4 during the TAI protocol directly impacts bovine fertility and will be discussed. [ABSTRACT FROM AUTHOR]

This study aimed to investigate functional variants in chromosome 14 (BTA14) and its impact in genomic selection for birth weight (BW), weaning weight (WW), and yearling weight (YW) in Nellore cattle. Genetic parameter estimation and the weighted single‐step genomic best linear unbiased prediction (WssGBLUP) analyses were performed. Direct additive heritability estimates were high for WW and YW, and moderate for BW. Trait‐associated variants distributed across multiple regions on BTA14 were observed in the weighted single‐step genome‐wide association studies (WssGWAS) results, implying a polygenic genetic architecture for weight in different ages. Several genes have been found in association with the weight traits, including the CUB And Sushi multiple domains 3 (CSMD3), thyroglobulin (TG), and diacylglycerol O‐acyltransferase 1 (DGAT1) genes. The variance explained per SNP was higher in six functional classes of gene regulatory regions (5UTR, CpG islands, downstream, upstream, long non‐coding RNA, and transcription factor binding sites (TFBS)), highlighting their importance for weight traits in Nellore cattle. A marginal increase in accuracy was observed when the selected functional variants (SV) information was considered in the WssGBLUP method, probably because of the small number of SV available on BTA14. The identified genes, pathways, and functions contribute to a better understanding of the genetic and physiological mechanisms regulating weight traits in the Nellore breed. [ABSTRACT FROM AUTHOR]

Simple Summary: The study aimed to estimate growth curves and genetic parameters for Nellore cattle using a random regression methodology. The dataset included 6974 calves raised in Pantanal, MS, Brazil, and 53,233 weight records, with at least four weighings per individual. The model considered direct and maternal genetic additive effects and maternal permanent environmental effects at random. Cubic orthogonal Legendre polynomials were used to fit the growth curve, with fixed effects of sex, year of birth, farm, calf birth month, and cow age at calving. The mean weights at 120 and 205 days were 93.43 kg and 180.42 kg, respectively. Animals born in the dry season had higher average weights, leading to higher weights at 646 days. Direct heritabilities ranged from 0.35 to 0.75, while maternal heritabilities were low (0.03 to 0.08). Random regression effectively adjusts growth curves and aids in selecting superior animals for breeding. The objective was to estimate the growth curves and genetic parameters using random regression methodology for Nellore cattle raised in Pantanal, MS, Brazil (6974 calves; n = 53,233 weights), with at least four weighings per individual. The model considered direct and maternal genetic additives and maternal permanent environmental effects at random. Orthogonal Legendre polynomials of cubic order were used to fit the growth curve. Analyses of variance were performed using the GLM procedure. The model used contained the fixed effects of sex, year of birth, farm, and the covariates calf birth month (linear and quadratic) and cow age at calving (linear and quadratic). The adjusted mean weight at 120 days of age was 93.43 ± 19.78 kg, and for 205 days of age, it was 180.42 ± 26.58 kg. Animals born in the dry season had a higher average weight [kg] (219.57 vs. 211.78, 3.7% higher) and, consequently, had higher weights at 646 days of age. Estimates of direct heritabilities (h2a) ranged from 0.35 to 0.75 (high magnitudes), and maternal heritabilities (h2m) along the trajectory of low magnitudes ranged from 0.03 to 0.08, respectively. The use of random regression to evaluate beef animals allows for adjusting the growth curve and selecting the best animals to be the parents of future generations. [ABSTRACT FROM AUTHOR]

Prior studies in beef cattle have shown shifts in the reproductive microbiome prior to artificial insemination (AI), yet few have characterized both the reproductive microbiome and immune responses prior to AI, particularly in purebred Bos indicus. Therefore, the aim of this study was to characterize the circulating cytokines and the vaginal microbiome of Bos indicus females prior to fixed-time artificial insemination (FTAI). Bos indicus females (n = 79) on four separate ranch operations within a 20-mile radius in East Texas were subjected to the 7-day CO-Synch + controlled intervaginal drug-releasing (CIDR) protocol beginning on day (d)-9 with FTAI on d0. Blood samples were collected on d-9 (CIDR IN), d-2 (CIDR OUT), and d0 (AI DAY) for cytokine concentration analyses using the RayBiotech Quantibody Bovine Cytokine Array Q1 kit per the manufacturer's instructions. Sterile vaginal swabs were inserted past the vulva, rotated, and stored at -80°C for microbiome analysis. Bacterial community analyses targeted the V4 hypervariable region of the 16S rRNA gene. Pregnancy status was determined by transrectal ultrasonography approximately 60 days after FTAI for resulting open females (n = 45) and pregnant females (n = 34). Regardless of pregnancy status, the vaginal relative abundance of Firmicutes differed between CIDR IN, CIDR OUT, and AI DAY (63.74% vs. 28.31% vs. 60.86% ± 3.66%, respectively; P < 0.01). Genera with phylum Firmicutes including Ruminococcus, Clostridium, Blautia, Butyrvibrio, and Mogibacterium followed a similar trend (P < 0.05). Butyrvibrio tended to have greater relative abundance in the vaginal samples of Cows than Heifers (4.17% ± 0.75% vs. 3.26% ± 0.77%;P=0.07). Concentrations of the interferon (IFN)g (2005.98 ± 471.94 pg/mL vs. 1185.40 ± 482.65 pg/mL; P < 0.01), interleukin (IL)1F5 (153.89 ± 141.07 pg/mL vs. 627.30 ± 149.28 pg/mL; P < 0.01), and interferon gamma-induced protein (IP)10 (9363.26 ± 2929.83 pg/mL vs. 5905.53 ± 2983.60 pg/mL; P = 0.05) were greater in Cows than Heifers. There was a parity-by-status interaction for IP10, with Open Cows having the greatest concentration compared all other groups (P < 0.05). These results indicate differences in circulating cytokines and shifts in the vaginal microbiome for in Bos indicus cattle prior to FTAI. [ABSTRACT FROM AUTHOR]

The present study evaluated follicular and endocrine dynamics during ReBreed21, a reproductive strategy that allows resynchronization of ovulation every 21 days in Bos indicus (Nelore) heifers. A synchronized estrous cycle was induced using a standard timed ovulation protocol (d −10: P4 implant inserted + 2 mg estradiol benzoate; d −2: P4 removed+ 0.5 mg cloprostenol + 0.6 mg estradiol cypionate + 200 IU equine chorionic gonadotropin (eCG); d0: 8.4 μg buserelin) without AI to ensure nonpregnancy in heifers. Day of GnRH was designated d0 of estrous cycle. On d12, heifers (n = 80) were randomized into three experimental groups: (1) ReBreed21 (n = 28) d12 P4 device inserted, d19 P4 device withdrawal plus 200 IU eCG, and d21 8.4 μg buserelin (GnRH); (2) ReBreed21+G (n = 26) same as ReBreed21 plus GnRH (16.8 μg) treatment on d12; and (3) Control (n = 26) no treatment. ReBreed21+G increased two-fold (62.9%; 18/26) percentage of heifers with synchronized follicular wave emergence compared to Control (34.6%; 9/26) whereas ReBreed21 (53.6%; 15/28) was intermediate. The ReBreeed21 groups (eCG on d19) increased (P < 0.01) follicular growth between d19 and d21 in ReBreed21 (2.3 ± 0.2 mm) and ReBreed21+G (3.4 ± 0.2 mm) compared with Control (1.2 ± 0.3 mm), resulting in greater (P < 0.01) follicle diameter on d21 for ReBreed21 (10.7 ± 0.4 mm) and ReBreed21+G (10.8 ± 0.4 mm) compared with Control (9.1 ± 0.5 mm). Structural luteolysis was similar among groups (P = 0.51), although the average day when P4 was <1 ng/mL was later (P < 0.01) for ReBreed21 (20.5 ± 0.2) and ReBreed21+G (20.7 ± 0.2) compared to Control (19.2 ± 0.4). Overall ovulation at the end of the estrous cycle was increased (P = 0.03) for ReBreed21 groups (83.3%; 45/54) compared with Control (57.7%; 15/26). Synchronized ovulation on day 22–23 was greater (P < 0.01) for ReBreed21 (78.6%; 22/28) and ReBreed21+G (76.9%; 20/26) compared with Control (30.8%; 8/26). Thus, the ReBreed21 resynchronization program produced acceptable endocrine and follicular dynamics, including synchronized ovulation at the end of the protocol in nonpregnant heifers providing good rationale for testing the fertility and practical implementation of this protocol under field conditions. • The P4 device maintained P4 concentrations and prevented early ovulation. • ReBreed21 strategy (P4+eCG) increased follicle growth rate (d19-21) vs. Control. • ReBreed21 had more synchronized ovulation (d22/23) than Controls (78 vs 27%). • ReBreed21 allows a timed ovulation in nonpregnant Bos indicus heifers every 21 days. [ABSTRACT FROM AUTHOR]

The cattle in the Pantanal region show a notable influence from Bos indicus breeds and their crossbreeds. However, a comprehensive biometric assessment of the reproductive system in these animals is currently lacking. This study evaluated the effects of breed, age, carcass weight, and estrous cycle phase on female reproductive system morphometry. A total of 124 healthy, non-pregnant reproductive tracts (83 Nelore and 41 Crossbred) were collected at a slaughterhouse. Neither the volume and weight of the ovaries nor the majority of uterine dimensions were affected by breed. Compared to heifers, cows showed longer uterine horns, a larger external caudal diameter of the uterine horns and body, and a greater external cranial diameter and internal caudal diameter of the cervix. The carcass weight (below vs. within commercial weight) affected the length of the uterine horns, uterine body, and cervix. Ovaries with a corpus luteum presented higher volume and weight than those with only follicles. Although the uterine measurements in the luteal phase were increased, the cycle stage did not affect the uterine morphometry. The average number of cervical rings was 5.0, independent of weight or breed. Crossbred animals presented a higher first cervical ring. Age didn´t influence the number, height, or distance between cervical rings. Deviation from the normal alignment of the cervix was recorded in 14.29 % of the animals, with a higher occurrence among Nelore cattle; deviation from the median axis was the most common (30%). This study emphasizes various parameters influencing the morphometry of the female reproductive system in Nelore cattle and their crosses, which could be crucial for implementing reproductive biotechnology techniques better suited to the morphological characteristics of zebu breeds. [ABSTRACT FROM AUTHOR]

Anti-Müllerian hormone (AMH) concentration and number of recovered oocytes (ROOC) are phenotypic parameters associated with in vitro embryo production (IVEP). More recently, anogenital distance (AGD) has been proposed as a proxy for fertility in dairy cattle that is easy to collect at a low cost. The aim of this study was to characterize the AGD and its phenotypic and genetic associations with AMH and IVEP in Bos indicus Gyr dairy cattle. The hypothesis was that the number of ROOC, in vitro–produced embryos, and AMH concentration would increase as the AGD decreases. From July to December 2021, a single morphometrical measurement of AGD was collected in 552 donors from 6 herds in Brazil. A subset of donors had AMH assayed on the same day. Only ovum pick-up events that occurred up to 12 mo preceding and 7 mo succeeding the AGD measurement were used to assess the association between AGD, AMH, and IVEP. Thus, 472 donors (1,551 ovum pick-up events and 140 donors with AMH) were considered in the analysis. A raw average was calculated for each individual donor's ROOC, viable oocytes, total produced embryos, viability rate, and embryo rate (defined as total produced embryos/viable oocytes). Comparisons were conducted within the age categories of 3 to <6 yr or 6 to <10 yr. Phenotypic associations were performed in SAS software (SAS Institute Inc., Cary, NC). Genetic correlations were estimated using the BLUPF90 family of programs. The AGD (128.7 mm ± 14; mean ± standard deviation) had a normal distribution and was highly variable (83 to 172 mm) among the Gyr population. Our experimental hypothesis was partially supported by a phenotypic association of a greater number of total produced embryos (R2 = 0.023) as AGD decreased. Our results failed to support an increase in AMH concentration along with a decrease in AGD. In addition, positive and low genetic correlations were observed between AGD and viable oocytes (r = 0.08), and embryo rate (r = 0.20). A greater number of viable oocytes and embryos were observed in donors in the high compared with intermediate and low ROOC categories within both age categories. The age interval of 3 to <6 yr showed a greater number of recovered and viable oocytes for the high AMH compared with the low category, but no differences were observed among the AGD categories. In summary, for the Gyr breed, AGD was phenotypically inversely associated with a quantity-related parameter, such as the total number of produced embryos. In contrast, AGD showed a low genetic correlation with qualitative-related outcomes such as viable oocytes and embryo rate. Further studies should be performed to validate these retrospective analyses and to better understand the association between AGD and IVEP. [ABSTRACT FROM AUTHOR]

Summary: This research aimed to evaluate the influence of different high‐intensity ultrasound (HIU) levels (control: 0; low: 276.36; moderate: 422.67; and high: 747.79 W cm−2) and stored in aerobic conditions for 7 days at 4 ± 1 °C on instrumental colour, metmyoglobin reducing activity (MRA), oxidative stability and texture of Longissimus lumborum (LL) from Nellore (Bos indicus) cattle. HIU moderate level samples exhibited higher (P < 0.05) lipid and protein oxidation, whereas high level showed higher MRA than control, low and moderate level counterparts. An increase (P < 0.05) of hue angle, MRA, lipid, and protein oxidation during refrigerated storage. Overall, the HIU levels did not influence pH, colour, texture, lipid, and protein oxidation, whereas HIU high level (HIU‐HL) improved the MRA contributing to beef colour stability. [ABSTRACT FROM AUTHOR]

This experiment evaluated pregnancy losses from day 30 of gestation to calving in Bos indicus females, and evaluated if serum haptoglobin concentrations during early gestation impacts subsequent pregnancy losses. A total of 4926 Nelore females were used, being 1802 nulliparous heifers inseminated as yearlings (precocious heifers), 1356 nulliparous heifers inseminated at 24 months of age (conventional heifers), 887 suckling primiparous cows, and 881 suckling multiparous cows. Cows were assigned to an ovulation synchronization + fixed-time artificial insemination (FTAI) protocol from day −11 to 0 of the experiment. Pregnancy status was verified using transrectal ultrasonography on days 30 and 60 after FTAI, via transrectal palpation on day 150 after FTAI, and according to calf birth. Blood samples were collected from all animals diagnosed pregnant on day 30 after FTAI, and analyzed for serum concentrations of haptoglobin and pregnancy associated glycoproteins (PAG). Pregnancy loss was greater (P < 0.01) from day 60–150 of gestation (10.2 %) compared with day 30–60 of gestation (6.0 %) and with day 150 of gestation to calving (7.4 %), and differed (P = 0.04) between these latter two periods. Pregnancy loss from day 30–60 of gestation did not differ (P = 0.26) among parities, whereas total pregnancy losses (day 30 to calving) were greater (P < 0.01) in precocious (28.4 %) and conventional (27.1 %) heifers compared with primiparous (16.4 %) and multiparous (13.0 %) cows. Serum PAG concentrations on day 30 after FTAI were less (P ≤ 0.03) in cows that lost the pregnancy (5.63 ng/mL) from day 30–60 of gestation, as well as those that lost the pregnancy from day 30 to calving (8.59 ng/mL) compared with cohorts that maintained the pregnancy (9.39 and 9.32 ng/mL, respectively). No differences in serum PAG concentrations on day 30 after FTAI were noted (P ≥ 0.23) according to pregnancy losses from day 60 to calving. Serum haptoglobin concentration on day 30 after FTAI also did not differ (P ≥ 0.48) between cows that maintained or lost the pregnancy. This experiment provides novel information about pregnancy losses after day 30 of gestation in B. indicus cattle, with most losses occurring as fetal mortality and not affected by systemic inflammation during early gestation. Pregnancy losses were nearly doubled in precocious and conventional heifers compared with parous cows, demonstrating the relevance of this reproductive failure to B. indicus replacement heifers. • Pregnancy loss is a major reproductive challenge in cow-calf operations. • Bos indicus females lost 22.1 % of the pregnancies after day 30 of gestation. • Most of these losses were caused by fetal mortality from day 60–150 of gestation. • Nulliparous heifers experienced greater pregnancy losses than parous cows. • Heifers inseminated as yearlings had the lowest reproductive rates among parities. [ABSTRACT FROM AUTHOR]

In vitro embryo production systems in buffaloes have great productive perspectives and opportunities for improvement. Among these, comparative studies with species with more significant advances in reproductive biotechnology have been developed. Accordingly, this work aimed to identify the differences in the electrophoretic profiles of proteins in the follicular fluid (FF) of cows and buffaloes and their possible association with follicle size. FF was obtained at the central abattoir in Medellín (Antioquia), Colombia, from small (<7 mm) and large (>7 mm) follicles from the ovaries of 25 cows (Bos indicus) and 20 buffaloes (Bubalus bubalis). The total protein content of the FF was quantified and subsequently depleted of albumin and immunoglobulins. Samples were subjected to denaturing electrophoresis in sodium dodecyl sulfate-polyacrylamide gels (SDS-PAGE) to determine the electrophoretic profiles using a photodocumenter. The values obtained for the relative amount of each band were compared between species and follicle sizes using the Mann-Whitney test. The results showed no significant differences in total protein concentration between the different follicle sizes and species. Further, 72.6% of the FF proteins are immunoglobulins and albumin. The profiles of small follicles (<7mm) in cows presented 19 bands and 11 in buffaloes. The molecular weight range of the bands detected was between 5 and 250 kDa. Quantitative differences of the proteins in the follicular fluids evaluated were identified. The information obtained may contribute to elucidating the physiological differences between large and small follicles but does not explain the differences between species. [ABSTRACT FROM AUTHOR]

Genome-wide deleterious mutations were identified in zebu cattle (Bos indicus) using in silico approach. The ddRAD sequence data of Sahiwal cattle were annotated and aligned with the cattle reference genome (ARS-UCD1.2). A total of 279,383 SNPs were identified at Read Depth10, which were further filtered to 692 missense SNPs. These SNPs were further analyzed, for functional consequences, by using Variant Effect Predictor, PolyPhen, PROVEAN, and PANTHER tools. A total of 18 SNPs, were finally identified as deleterious, and among these, 12 SNPs were mapped on nine different genes. ERRAT, ProSA-web, Project HOPE, TM-Align, and YASSARA tools, further confirmed the protein malfunctioning of one missense (L290V) mutation of Retinoblastoma binding protein-5 (RBBP5) gene, transcribing a cell cycle regulatory protein and associated with Retinoblastoma in human. This derived bioinformatics pipeline may be useful for preliminarily identifying the deleterious DNA mutations in livestock, specifically in absence of any genetic disease records. [ABSTRACT FROM AUTHOR]

This study aimed to characterize estrus response and to establish relationships between intensity of estrus, preovulatory follicle (POF) size and estradiol (E2) concentrations on day of AI, luteal profiles and pregnancy outcome in lactating Hariana breed of cows. 200 cyclic cows were subjected to Ovsynch (n = 54) and Pre-OV treatment (n = 146). Ovsynch: Buserelin acetate (BA; 10 µg), Cloprostenol (500 µg) and BA (10 µg) were injected i.m. on day 0, 7 and 9, respectively, irrespective of treatment. Pre-OV: BA (10 µg) and Cloprostenol (500 µg) was also injected i.m. simultaneously 7 days prior to initiate Ovsynch. On the basis of estrus behavior, the cows were classified into three groups: weak, moderate and intense. Artificial insemination performed at 18–24 hours after 2nd BA of Ovsynch in both treatments. The average duration of estrus did not differ (p > 0.05) between Ovsynch and Pre-OV treatment. A positive correlation was observed between estrus response and POF size, concentration of E2 on day of AI and luteal profiles on day 12 post-AI. First service conception rate was higher in cows exhibited intense (45.46%) and moderate (42.56%) estrus response than weak (28.57%) estrus response. In conclusion, intensity of estrus expression could be considered as important determinant for deciding pregnancy outcomes in Bos indicus cows. [ABSTRACT FROM AUTHOR]

Background: For the successful reproduction in Kangayam cows, adequate nutrition containing sufficient quantum of minerals is necessary. Minerals are important cofactors in majority of the metabolic and immune reactions and hormone synthesis that could affect reproduction. Present study was planned to analyse whether mineral levels change in different treatment days following estrus induction and corresponding changes in stages of the estrous cycle. Methods: Non pregnant, pluriparous Kangayam cow (n= 70) were allotted to control and different treatment protocols (each consist of 10 cows) based on the transdermal (PNC based groups) and transvaginal application of progesterone (CIDR based group) with a shot of PGF2α; one day preceding the day of progesterone removal. Ovulation was induced either using estradiol benzoate or buserelin acetate. Mineral profiles were analysed on the day of progesterone application (APP), removal (REM), AI and 10 days post insemination (10 DPAI). Result: It indicated that changes in the mineral levels between the treatment days especially on the day of AI and 10DAPAI could be correlated with the corresponding follicle and luteal phases and it could be concluded that there were significant changes especially in selenium, manganese, zinc and copper levels between the treatment days in each group which could be extrapolated to have specific roles in stages of estrous cycle. Among these minerals copper levels could be correlated to affect the steroid concentration by altering its metabolism thereby its clearance in Bos indicus breed ie Kangayam breed of Tamil Nadu. [ABSTRACT FROM AUTHOR]

Susceptibility to classical bovine spongiform encephalopathy (BSE) has been linked to 23 bp indel in promoter and 12 bp indel in the first intron of cattle prion protein gene. This study aimed to investigate 23/12 bp indel polymorphisms in the polymorphisms in cattle prion protein (PRNP) gene to reveal the risk of BSE in Ethiopian cattle. Also, frequency of each polymorphism was compared to the other Bos taurus and Bos indicus breeds. According to results, the insertion variant was detected at a low frequency in all of the study populations at both loci. The 23 bp insertion allele in Fogera breed was relatively lower than Borona and Arsi and the same allele at the same locus in Afar breed was higher than the rest of the breeds (0.16). Due to high linkage disequilibrium (LD) of the deletion allele in Bos taurus, the frequencies of deletion allele at 23 bp (0.84) and 12 bp (0.86) loci in Afar breed were relatively closer than the rest of the breeds. In addition, DD/DD was found as the highly frequent diplotype in all of the breeds. The low frequency of insertion alleles at 23 and 12 bp indel sites demonstrate that Ethiopian cattle have a genetically high risk for BSE. [ABSTRACT FROM AUTHOR]

In order to estimate the Basic Quality Grade of beef carcasses according to bone maturity, marbling and Bos indicus racial predominance, data from 1,417 carcasses processed in four Federal Inspection Type establishments were analyzed. The following variables were recorded: cavitary fat, rib eye area, dorsal fat thickness, hump length and height, marbling, and bone maturity. Using the variables marbling and bone maturity, the Basic Grade of Quality was estimated in accordance with the norm NOM-004-SAGARPA-2018. The hump height was used as a criterion to determine racial predominance, and four groups were generated from this information. Based on the recorded values, descriptive statistics, analysis of variance, comparison of means, and Tukey's test were determined. The hump height in each group was 7.19, 10.54, 14.38, and 20.11 cm (P<0.01), respectively. 82 % of the carcasses were predominantly Bos indicus. The hot carcass weight was 310.05 kg for group 1 vs 326.99 kg for group 4 (P<0.01). The rib eye area was 85.59 cm² for group 1 vs 89.14 cm² for group 2 (P<0.05). Of the total number of carcasses evaluated, 60 were classified as Supreme quality (4.23 %), 655 as Select quality (46.22 %), 621 as Standard quality (43.82 %), and 81 as Commercial quality (5.72 %). The beef carcasses in this study have mainly a Bos indicus breed component, and their Basic Quality Grade corresponded primarily to a greater number of carcasses with grade A bone maturity, but with less marbling. [ABSTRACT FROM AUTHOR]

This article discusses the development of genetically improved tropical-adapted dairy cattle, focusing on the challenges and potential solutions for increasing productivity in tropical regions. It explores the traits of interest from different genetic groups and the success of strategic breeding programs, such as the Girolando breed in Brazil. The article also highlights the University of Illinois Tropical-Adapted Cattle Project in Tanzania, which aims to enhance the livestock sector and improve livelihoods in the country. It addresses the specific challenges faced by Tanzania, including low livestock productivity, feed scarcity, and climate change, and emphasizes the importance of the Maasai people and their cultural significance in cattle raising. The report provides a comprehensive analysis of the topic and is a valuable resource for library patrons conducting research in this area. [Extracted from the article]

The present investigation was performed to compare the global gene expression profile in peripheral blood mononuclear cells (PBMCs) of Bos indicus and crossbred (Bos taurus × B. indicus) cattle. Previously, several studies revealed the disease tolerance potential of B. indicus cattle but underlying genetic mechanism is still not fully explored. The PBMCs model was used for this investigation as it plays crucial role in the immune system regulation. Transcriptomic analysis revealed total 6767 significantly differentially expressed transcripts (fold change (absolute) >2.0, p <.05). In addition, 4149 transcripts were upregulated, 2618 transcripts were downregulated and fold change (absolute) of differentially expressed transcript varied from −223.32 to 213.63. Functional annotation analysis of differentially expressed genes confirmed their role in various molecular pathways viz. innate immune response, antigen processing and presentation, MHC protein complex, defense response to bacterium, regulation of immune response, positive regulation of JAK-STAT cascade, cytoskeletal protein binding, etc. Protein–protein interaction network analysis provided understanding of inter-relationship of immune genes with differentially expressed genes. In conclusion, this study could provide comprehensive information about the dysregulated genes and biological pathways in PBMCs which might be responsible for disease tolerance in B. indicus cattle. [ABSTRACT FROM AUTHOR]

Context: Recent advances in molecular technology have allowed us to examine the cattle genome with an accuracy never before possible. Genetic variations, both small and large, as well as the transcriptional landscape of the bovine genome, have both been explored in many studies. However, the topological configuration of the genome has not been extensively investigated, largely due to the cost of the assays required. Such assays can both identify topologically associated domains and be used for genome scaffolding. Aims: This study aimed to implement a chromatin conformation capture together with long-read nanopore sequencing (Pore-C) pipeline for scaffolding a draft assembly and identifying topologically associating domains (TADs) of a Bos indicus Brahman cow. Methods: Genomic DNA from a liver sample was first cross-linked to proteins, preserving the spatial proximity of loci. Restriction digestion and proximity ligation were then used to join cross-linked fragments, followed by nucleic isolation. The Pore-C DNA extracts were then prepped and sequenced on a PromethION device. Two genome assemblies were used to analyse the data, namely, one generated from sequencing of the same Brahman cow, and the other is the ARS-UCD1.2 Bos taurus assembly. The Pore-C snakemake pipeline was used to map, assign bins and scaffold the draft and current annotated bovine assemblies. The contact matrices were then used to identify TADs. Key results: The study scaffolded a chromosome-level Bos indicus assembly representing 30 chromosomes. The scaffolded assembly showed a total of 215 contigs (2.6 Gbp) with N50 of 44.8 Mb. The maximum contig length was 156.8 Mb. The GC content of the scaffold assembly is 41 ± 0.02%. Over 50% of mapped chimeric reads identified for both assemblies had three or more contacts. This is the first experimental study to identify TADs in bovine species. In total, 3036 and 3094 TADs across 30 chromosomes were identified for input Brahman and ARS-UCD1.2 assemblies respectively. Conclusions: The Pore-C pipeline presented herein will be a valuable approach to scaffold draft assemblies for agricultural species and understand the chromatin structure at different scales. Implications: The Pore-C approach will open a new era of 3D genome-organisation studies across agriculture species. The availability of highly complete and contiguous genome assemblies in agricultural species will enable precise identification of genetic variations, from single nucleotide polymorphisms to large structural variants. Using Pore-C pipeline, the high-quality genome assembly for Bos indicus species and higher-order 3D chromatin structure are first provided in one assay, offering a precious resource for understanding gene regulation. The Pore-C approach will open a new era of 3D genome organisation studies across agriculture species. [ABSTRACT FROM AUTHOR]

Background: As one of the important genetic resources for Ongole beef cattle, the study aimed to identify any potential polymorphisms in the Bone Morphogenetic Protein 15 gene in a group of Sumba Ongole (SO) cattle. Methods: Blood samples from 161 SO cattle were obtained and examined. The initial stage was the isolation of deoxyribonucleic acid (DNA). The next procedures were electrophoresis and extraction, followed by annealing temperature optimization, amplification and sequencing. The Basic Local Alignment Search Tool (BLAST) was used to examine the sequencing findings. The annealing temperature was 58°C for 15 seconds, with an amplification gain of 350 base pairs (bp). Result: The result showed that there were six single nucleotide polymorphisms (SNPs) of the BMP 15 gene in this region. Six mutations were SNP c.57 G>A, SNP c.120 C>T, SNP c.338 G>T, SNP c.360 C> A, SNP c.361 G>T, SNP c.365 A>T. The polymorphic informative content (PIC) value (0.25<=PIC<=0.5) was reached from low (0.02) to moderate high (0.45 and 0.47). A total of 2 SNPs in the BMP 15 gene with moderate-high PIC value was c.360 C>A and c.365 A>T. In conclusion, we reported for the first time the polymorphism of the BMP 15 gene which is required for further investigation as to whether this polymorphic could be responsible for reproductive trait variations in Ongole cattle. [ABSTRACT FROM AUTHOR]

Every week, 1–2 breeds of farm animals, including local cattle, disappear in the world. As the keepers of rare allelic variants, native breeds potentially expand the range of genetic solutions to possible problems of the future, which means that the study of the genetic structure of these breeds is an urgent task. Providing nomadic herders with valuable resources necessary for life, domestic yaks have also become an important object of study. In order to determine the population genetic characteristics, and clarify the phylogenetic relationships of modern representatives of 155 cattle populations from different regions of the world, we collected a large set of STR data (10,250 individuals), including unique native cattle, 12 yak populations from Russia, Mongolia and Kyrgyzstan, as well as zebu breeds. Estimation of main population genetic parameters, phylogenetic analysis, principal component analysis and Bayesian cluster analysis allowed us to refine genetic structure and provided insights in relationships of native populations, transboundary breeds and populations of domestic yak. Our results can find practical application in conservation programs of endangered breeds, as well as become the basis for future fundamental research. [ABSTRACT FROM AUTHOR]

India has 50 registered breeds of native cattle (Bos indicus) which are locally adapted to diverse environmental conditions. This study aimed to investigate the genomic basis of adaptation of native Indian cattle and to predict the impact of key SNPs on the amino acid changes that affect protein function. The Illumina 777 K BovineHD BeadChip was used to genotype 178 native cattle belonging to contrasting landscapes and agro-climatic conditions. The genotype-environment association was investigated with R. SamBada, using 5,74,382 QC passed SNPs and 11 predictor variables (10 multi-collinearity controlled environmental variables and 1 variable as "score of PCA" on ancestry coefficients of individuals). In total, 1,12,780 models were selected as significant (q < 0.05) based on G score. The pathway ontology of the annotated genes revealed many important pathways and genes having a direct and indirect role in cold and hot adaptation. Only ten SNP variants had a SIFT score of < 0.05 (deleterious), and only two of them, each lying in the genes CRYBA1 and USP18, were predicted to be deleterious with high confidence. RaptorX predicted the tertiary structures of proteins encoded by wild and mutant variants of these genes. The quality of the models was determined using Ramachandran plots and RaptorX parameters, indicating that they are accurate. RaptorX and I-Mutant 2.0 softwares revealed significant differences among wild and mutant proteins. Adaptive alleles identified in the present investigation might be responsible for the local adaptation of these cattle breeds. [ABSTRACT FROM AUTHOR]

Pregnancy loss (PL) has important impacts on the profitability of livestock production systems, although it is not widely reported, particularly in Bos indicus cattle. The present study retrospectively evaluated PL after timed-artificial insemination (TAI) in Bos indicus (Nelore) beef cows corresponding to several factors, such as parity, body condition score (BCS), presence of corpus luteum (CL) at the beginning of TAI protocols, expression of estrus, and hormonal manipulations during the TAI protocol. Data from two experiments performed during three breeding seasons (BS) were reanalyzed. Both experiments evaluated adding GnRH treatment at TAI in a 7-d estradiol (E2) plus progesterone (P4)-based protocol, with intravaginal P4 implant removal on Day 7 combined with treatment with 0.5 or 1.0 mg E2 cypionate and 300 IU eCG, and TAI on Day 9. In addition, during BS 2 and 3 (Exp 2), cows were randomized to receive or not a PGF treatment on Day 0 (beginning of the TAI protocol). In all BS, presence of CL and BCS were evaluated at the beginning of TAI protocols, follicle size and expression of estrus were evaluated at TAI. The PL was assessed between the first pregnancy diagnosis (∼35d) and parturition. There were no effects of hormonal manipulations within TAI protocols of different BS on PL. There was no interaction between GnRH treatment at TAI and the other variables within BS, and there was no main effect of GnRH treatment on PL (without = 10.1% [102/1007] vs. with = 10.4% [114/1100]). The addition of PGF on Day 0 had no effect on PL (11.5% [102/886] vs. 10.5% [89/850]), as well as EC dose to induce final ovulation (10.8% [89/827] vs. 11.2% [102/909] for 0.5 and 1.0 mg, respectively). Primiparous had greater PL than multiparous cows (14.0% [77/550] vs. 8.9% [139/1557]), and cows not expressing estrus near TAI had greater PL than those expressing estrus (13.5% [57/422] vs. 9.7% [156/1617]). There was no interaction between follicle size at TAI and GnRH treatment on PL. However, probability of PL decreased linearly as follicle size at TAI increased. There were no effects of service number (first TAI or resynchronization), BCS, or presence of CL on D0 on PL. In addition, PL was not affected by sire within any of the BS. In conclusion, some factors that are known to impact pregnancy per AI also influenced PL, such as parity and expression of estrus, although, other aspects such as BCS, number of services, and presence of CL on D0 did not affect PL. Moreover, commonly implemented treatments to increase fertility (e.g., PGF on Day 0 and increasing EC dose to 1.0 mg) did not affect PL. Finally, the GnRH treatment at TAI had no effect on PL and did not interact with any of the variables, an important result, since GnRH at TAI also increases fertility in Bos indicus beef cows. • Primiparous and cows not expressing estrus by the end of timed-AI protocols had greater pregnancy loss. • Presence of corpus luteum and body condition score did not influence pregnancy loss in beef cows. • The GnRH treatment at the time of AI did not increase pregnancy loss in beef cows submitted to E2 plus P4-based protocols. [ABSTRACT FROM AUTHOR]

The rumen and the jejunum of calves have distinct functional roles; the former is in the storage and fermentation of feed, and the latter is in transporting digesta to the ileum. It is unknown how nutrition changes the evolution of the microbiome of these organs after birth. We sequenced and characterized the entire microbiome of the rumen and the jejunum from Bos indicus calves of the Mexican Tropics to study their dynamics at Days 0, 7, 28, and 42 after birth. Operational taxonomic units (OTUs) belonging to 185 and 222 genera from 15 phylum were observed in the organs, respectively. The most abundant OTUs were Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. We observed that proteobacterial species were outcompeted after the first week of life by Bacteroidetes and Firmicutes in the rumen and the jejunum, respectively. Moreover, Prevotella species were found to predominate in the rumen (36% of total OTUs), while the jejunum microbiome is composed of small proportions of several genera. Presumably, their high relative abundance assists in specialized functions and is more likely in fermentation since they are anaerobes. In summary, the rumen and the jejunum microbiomes were outcompeted by new microbiomes in a dynamic process that begins at birth. [ABSTRACT FROM AUTHOR]

Among different cattle types, Bos indicus are known for their ability to better resist the tropical microbial infections comparatively, wherein MHC molecules play a significant role. In this study allelic diversity at MHC locus, DQA of Bos indicus, Bos taurus and crossbred of taurine-indicus has been explored to understand the possible role of MHC region in differential immune response. Thirty nine different DQA alleles were identified, out of which 14 were novel, along with documentation of duplication of DQA alleles. Indicus cattle population presented diverse types of DQA alleles compared to crossbred and exotic. Translated amino acid sequence analysis indicated, codon 64 and 50 of peptide binding sites being highly polymorphic and most of the indicus cattle presented alanine and arginine amino acid at position 64 and 50. Within breed genetic variation found to be higher than between breeds. Because of their ability to bind and subsequently respond to a wide array of antigens, the newly identified DQA alleles with high diversity present in the form of duplicated haplotypes in different combinations in cattle populations provided significant insights into probable role of this MHC locus in better tropical disease combating ability and genetic fitness of indicus cattle. [ABSTRACT FROM AUTHOR]

In Mexico, the genetic evaluations in Zebu breeds began in 2011 and there are no studies about the genetic progress achieved. Thus, this research aimed to quantify and analyse the genetic progress for growth traits in the Mexican Zebu beef cattle populations Nellore, Sardo Negro, Gyr, Indubrasil, and Guzerat. The genetic trends were obtained through weighted regression (by the number of animals) of estimated breeding values for direct birth weight, direct and maternal weaning weight, yearling weight, and weight at 540 days of age, on the year of birth. Genetic trends were also estimated by the four selection paths, groups of herds, and weighted averages of the sires' breeding values. The results showed genetic gain as expected of genetic improvement. Nellore presented the highest positive gains for all the traits, and Gyr had the smallest gains among the breeds. Guzerat showed contrary trends for weights until weaning, and had more favourable trends for weights after weaning than the other breeds. The genetic gains obtained for the growth traits reflected the strong influence of the selection made via the maternal paths. The results between weighted and unweighted average breeding values indicate no effective strategy for disseminating genetic material with high breeding values. The genetic gains obtained in the whole populations were due to the main groups of herds. Thus, to achieve further genetic progress, it is necessary to design a cooperative breeding program with a strategy for disseminating that genetic material. The evaluated populations are developed in the context of tropical livestock, with specific selection criteria and objectives. Genetic trends assess the direction and magnitude of genetic change. The results in the genetic trends show the consequences of the genetic improvement schemes carried out by the breeders. For breeders, it is important to evaluate and monitor genetic improvement schemes, and where appropriate, adjust, or redefine selection criteria and objectives. [ABSTRACT FROM AUTHOR]

Bos taurus × Bos indicus crosses are widespread in tropical and subtropical regions, nonetheless, quantitative information about the influence of B. indicus genetics on the reproductive performance of beef cattle is lacking. Herein, we determined the association between level of B. indicus genetics and reproduction from a 31-yr dataset comprising sequential breeding seasons of the University of Florida multibreed herd (n = 6,503 Angus × Brahman cows). The proportion of B. indicus genetics in this herd is evenly distributed by each 1/32nd or approximately 3-percentage points. From 1989 to 2020, the estrous cycle of cows was synchronized for artificial insemination (AI) based on detected estrus or timed-AI (TAI) using programs based on gonadotropin-releasing hormone and prostaglandin, and progestin/progesterone. All cows were exposed to natural service after AI and approximately 90-d breeding seasons, considering the day of AI as day 0. The proportion of B. indicus genetics of cows was associated negatively with pregnancy per AI, ranging from 51.6% for cows with 0%–19% of B. indicus genetics to 37.4% for cows with 81%–100% of B. indicus genetics. Similar association was found for estrous response at the end of the synchronization protocol, ranging from 66.3% to 38.4%, respectively. This reduced estrous response helped to explain the pregnancy results, once the pregnancy to AI of cows showing estrus was 2.3-fold greater than for those not showing estrus and submitted to TAI. Despite reduced pregnancy per AI, the increase in the proportion of B. indicus genetics of cows was not associated with a reduction in the proportion of pregnant cows at the end of the breeding season. Nevertheless, the interval from entering the breeding season to pregnancy was lengthened as the proportion of B. indicus genetics of cows increased. The median days to pregnancy was extended by 25 when the proportion of B. indicus genetics surpassed 78% compared with less than 20%. Thus, the increase in the proportion of B. indicus genetics of cows was related to a reduction in pregnancy per AI and lengthening the interval to attain pregnancy during the breeding season, but not with the final proportion of pregnant cows. As a result, reproductive management strategies directed specifically to cows with a greater proportion of B. indicus genetics are needed to improve the rate of pregnancy in beef herds. [ABSTRACT FROM AUTHOR]

Objective: As one of the most valuable genetic resources of Ongole beef cattle globally, the Sumba Ongole (SO) cattle population is being studied in this investigation of myostatin (MSTN) gene polymorphism and its association with growth traits. Materials and Methods: Blood samples from 161 SO cattle were collected and analyzed. Deoxyribonucleic acid (DNA) was isolated. The DNA was electrophoresed and extracted, and finally, the annealing temperature was optimized, followed by amplification and sequencing. Next, we used a Basic local alignment search tool to assess the sequencing data. Results: The analysis revealed 22 single nucleotide polymorphisms (SNPs) in the MSTN gene in this region that showed genetic variation. Two SNPs, c.424 G > A, and c.467 G > C, were found to be significantly associated with SO cattle phenotypes of wither height, heart girth, and hip height (p < 0.05) but not with body weight or body length (p > 0.05). Conclusion: As a result of our findings, the MSTN gene polymorphism and its correlation with growth traits in SO cattle may be employed as a candidate marker in SO cattle and other beef cattle breeds. [ABSTRACT FROM AUTHOR]

Objective: This study investigated the effects of administering saline, 100 or 250 μg of gonadotrophin releasing hormone (GnRH) on ovarian response, synchrony of oestrus and ovulation and chronic stress response in Bos indicus cattle. Design: Randomised control. Methods: Animals were either left untreated (n = 20) or on day 0 treated with an intravaginal progesterone releasing device and either saline (n = 24), 100 μg (n = 35), or 250 (n = 35) μg of GnRH, intramuscular (IM). Blood was sampled 1.4 h after administration of treatment to monitor concentrations of luteinising hormone (LH) and P4 in serum and again 5 days later. On day 5 intravaginal P4 releasing device were removed, cloprostenol was administered IM and again 8 h later. Oestrus and ovulation were then monitored with ultrasonography for 6.5 days. Hair was clipped on day 55 for analysis of hair cortisol concentrations (HCC). Results: No significant differences were found between Saline and GnRH treatments in the odds of inducing a new corpus luteum (CL) and the synchrony of oestrus or ovulation. HCC did not differ significantly between treatments. Mean concentrations of LH in serum on day 0 were less in the Saline compared to 100 and 250 μg GnRH treatments but did not differ between different doses of GnRH. Conclusion: Mean concentrations of LH and the odds of inducing a new CL were not increased after administering 250 μg compared to 100 μg of GnRH. Animal handling events in the study did not influence HCC. Further research is needed to better optimise responses to GnRH in B. indicus cattle. [ABSTRACT FROM AUTHOR]

This study aimed to integrate analyses of structural variations and differentially expressed genes (DEGs) associated with the beef fatty acid (FA) profile in Nellore cattle. Copy numbers variation (CNV) detection was performed using the penncnv algorithm and CNVRuler software in 3794 genotyped animals through the High‐Density Bovine BeadChip. In order to perform the genomic wide association study (GWAS), a total of 963 genotyped animals were selected to obtain the intramuscular lipid concentration and quantify the beef FA profile. A total of 48 animals belonging to the same farm and management lot were extracted from the 963 genotyped and phenotyped animals to carry out the transcriptomic and differentially expressed gene analyses. The GWAS with extreme groups of FA profiles was performed using a logistic model. A total of 43, 42, 66 and 35 significant CNV regions (p < 0.05) for saturated, monounsaturated, polyunsaturated and omega 3 and 6 fatty acids were identified respectively. The paired‐end sequencing of 48 samples was performed using the Illumina HiSeq2500 platform. Real‐time quantitative PCR was used to validate the DEGs identified by RNA‐seq analysis. The results showed several DEGs associated with the FA profile of Longissimus thoracis, such as BSCL2 and SAMD8. Enriched terms as the cellular response to corticosteroid (GO:0071384) and glucocorticoid stimulus (GO:0071385) could be highlighted. The identification of structural variations harboring candidate genes for beef FA must contribute to the elucidation of the genetic basis that determines the beef FA composition of intramuscular fat in Nellore cattle. Our results will contribute to the identification of potential biomarkers for complex phenotypes, such as the FA profile, to improve the reliability of the genomic predictions including pre‐selected variants using differentiated weighting in the genomic models. [ABSTRACT FROM AUTHOR]

Cattle have been essential for the development of human civilization since their first domestication few thousand years ago. Since then, they have spread across vast geographic areas following human activities. Throughout generations, the cattle genome has been shaped with detectable signals induced by various evolutionary processes, such as natural and human selection processes and demographic events. Identifying such signals, called selection signatures, is one of the primary goals of population genetics. Previous studies used various selection signature methods and normalized the outputs score using specific windows, in kbp or based on the number of SNPs, to identify the candidate regions. The recent method of iSAFE claimed for high accuracy in pinpointing the candidate SNPs. In this study, we analyzed whole-genome resequencing (WGS) data of ten individuals from Austrian Fleckvieh (Bos taurus) and fifty individuals from 14 Chinese indigenous breeds (Bos taurus, Bos taurus indicus, and admixed). Individual WGS reads were aligned to the cattle reference genome of ARS. UCD1.2 and subsequently undergone single nucleotide variants (SNVs) calling pipeline using GATK. Using these SNVs, we examined the population structure using principal component and admixture analysis. Then we refined selection signature candidates using the iSAFE program and compared it with the classical iHS approach. Additionally, we run Fst population differentiation from these two cattle groups. We found gradual changes of taurine in north China to admixed and indicine to the south. Based on the population structure and the number of individuals, we grouped samples to Fleckvieh, three Chinese taurines (Kazakh, Mongolian, Yanbian), admixed individuals (CHBI_Med), indicine individuals (CHBI_Low), and a combination of admixed and indicine (CHBI) for performing iSAFE and iHS tests. There were more significant SNVs identified using iSAFE than the iHS for the candidate of positive selection and more detectable signals in taurine than in indicine individuals. However, combining admixed and indicine individuals decreased the iSAFE signals. From both within-population tests, significant SNVs are linked to the olfactory receptors, production, reproduction, and temperament traits in taurine cattle, while heat and parasites tolerance in the admixed individuals. Fst test suggests similar patterns of population differentiation between Fleckvieh and three Chinese taurine breeds against CHBI. Nevertheless, there are genes shared only among the Chinese taurine, such as PAX5, affecting coat color, which might drive the differences between these yellowish coated breeds, and those in the greater Far East region. [ABSTRACT FROM AUTHOR]

The selection of climate resilient animal is necessary to secure the future of sustainable animal production. The present investigation therefore was an effort to unravel answers to the adaptation at physiological, hematological, and molecular levels in cows of hot arid region that helps them to survive harsh environment, to continue production and reproduction. This investigation was carried out in indicine cows over a period of one year, encompassing four seasons, wherein physiological data of 50 animals, hematological data of 15 animals, and gene expression profile of 5 animals from each of Sahiwal and Kankrej breeds per season was generated. In total, 5600 physiological observations, 1344 hematological observations, and 480 molecular samples were processed. The meteorological data revealed a high diurnal variation of temperature across seasons, with THI exceeding 80 during the months of summer and hot-humid seasons, indicating significant heat stress (HS). The physiological parameters showed an increasing trend with the incremental THI, with significantly (p < 0.05) higher values of rectal temperature (RT), respiration rate (RR), pulse rate (PR), and body surface temperature (BST) at ventral (VT), lateral (LT), dorsal (DT), and frontal (FT), in both breeds recorded during HS. The hematological pictures also revealed significant (p < 0.05) seasonal perturbations in erythrocytic and leucocytic parameters. Moreover, the molecular response was driven by a significant (p < 0.05) upregulation of all the key HSPs, HSP70, HSP90, HSP60, and HSP40, except HSP27 during the hotter months of summer and hot-humid seasons. The expression of HSF1, an important transcriptional regulator of HSP70 was also significantly (p < 0.05) upregulated during summer season in both breeds. All the molecular chaperones revealed a significant upregulation during the summer season, followed by a decreasing trend by hot-humid season. The study indicated a well-developed thermotolerance mechanism in animals of both breeds, with Kankrej cows exhibiting better thermotolerance compared to Sahiwal cows. [ABSTRACT FROM AUTHOR]

We aimed to compare the effects of use of 1 or 2 mg estradiol benzoate (EB) associated with an intravaginal progesterone (P4) device for resynchronization of ovulation 14 days after timed-AI (TAI) in suckled beef cows. Nelore cows were submitted to a TAI (D0) and on D14, received an intravaginal P4 device and were randomly assigned to EB-1 group [n = 516] or EB-2 group [n = 510], which that received 1 or 2 mg EB, respectively. Also, cows had the ovaries scanned by ultrasound to detect an active CL on D14. On D22, devices were removed and structural luteolysis was detected by color-Doppler ultrasonography. In cows which underwent luteolysis, the resynchronization protocol was continued and they were submitted to second TAI on D24. Pregnancy diagnosis was performed 30–35 days after first or second TAI. A subgroup [n = 18–19/group] was submitted to daily ovarian ultrasound scanning from D14 to D22. Proportion of cows with an active CL on D14 did not differ (P > 0.1) between EB-1 and EB-2 groups. The proportion of cows with an active CL on D22 and pregnancy per AI (P/AI) at first TAI were greater (P ≤ 0.05) in EB-1 (55% and 51%) than in EB-2 group (48% and 42%). The P/AI at second TAI did not differ (P > 0.1) between EB-1 (47% [106/227]) and EB-2 group (42% [110/259]). Cumulative pregnancy rate was greater in EB-1 (73% [370/508]) than in EB-2 group (64% [322/502]). No difference (P > 0.1) was observed in the proportion of non-pregnant cows with a synchronized follicular wave emergence between EB-1 and EB-2 groups. In conclusion, treatment with either 1 or 2 mg EB associated with an intravaginal P4 device at D14 after TAI are efficient to synchronize a new follicular wave emergence. The decreased P/AI from first TAI observed in the group of cows receiving 2 mg indicates that this dose is not recommended for use in resynchronization programs initiated 14 days after TAI. The use of 1 mg EB associated with a P4 device provides an elevated cumulative pregnancy rate after two TAIs with an interval of 24 days. • Treatment with 1 or 2 mg estradiol benzoate (EB) and a P4 device at 14 days after TAI are efficient to synchronize follicular wave emergence. • Pregnancy establishment is impaired by use of 2 mg EB for resynchronization at 14 days after TAI. • The use of 1 mg EB is safer and results in improved pregnancy rates in the resynchronized cows after two TAIs. • Cows with low BCS have reduced presence of CL at resynchronization and increased early pregnancy loss. [ABSTRACT FROM AUTHOR]

This study analyzed the Sardo Negro breed pedigree (41,521 animals registered from 1958 to 2019) to determine its structure, evolution, and genetic variability (GV). The population genetic parameters evaluated were effective number of founders (fe) and ancestors (fa), pedigree integrity, additive genetic relationship (AGR); number of complete generations (NCG), maximum generations traced (NMGT), and equivalent complete generations (NECG); effective population size (Ne), inbreeding coefficient (F), and generation interval (GI). The average GI was 7.45 years. A total of 7,804 founders and 4,856 ancestors were identified for a fe of 185 and a fa of 97. The average and maximum values of NCG, NECG, and NMGT were 1.6 and 5.0, 2.5 and 6.5, 4.3 and 12, with Ne estimates of 15.9, 25.9, and 69.0, respectively. The increase in F, linked to Ne, ranged from 0.72% to 3.1% per generation. The average values for F and AGR were 3.6% and 1.0%, respectively. The proportion of inbred individuals was 32.0%, with F values ranging from 0.01 to 62.2% and an average of 11.3%. The rate of inbred population was 1.3% per year. The annual rate of AGR was 0.04%. For the continuity and projection of the breed, the evolution of F as a function of Ne and the possible implications of the selection schemes must be considered. The genetic variability sustained over time results from the Ne. [ABSTRACT FROM AUTHOR]

Objective: To investigate if modification of a gonadotrophin‐releasing hormone (GnRH) based protocol to synchronise oestrus in Bos indicus cattle will improve response rates to the first administration of GnRH and improve pregnancy rates to artificial insemination (AI). Design: Randomised control study. Methods: Bos indicus heifers, nonlactating and lactating cows allocated to a GnRH‐18 treatment (n = 237) were treated with an intravaginal device (IVD) and cloprostenol (0.5 mg IM) on day −11 and on day 0 remaining animals in the GnRH‐7 treatment (n = 222) were administered an IVD and every animal was treated with GnRH (100 μg IM). On day 7, equine chorionic gonadotrophin (400 IU IM) and cloprostenol were administered and IVD's were removed. Animals detected in oestrus on day 9 were artificially inseminated while those not detected in oestrus were administered GnRH (100 μg IM) at 1700 hours and inseminated on day 10. Bulls were inserted 2 weeks after completion of AI and remained until day 65. Results: The GnRH‐18 protocol increased the diameter of the largest follicle in the ovary on day 0, increased the percentage of new CL's induced after day 0 (46.3% vs 36.1%, for GnRH‐18 and GnRH‐7; P = 0.022), decreased circulating concentrations of progesterone on day 7 and increased odds of pregnancy to AI in heifers but not in nonlactating and lactating cows. Conclusion: Treatment with the GnRH‐18 compared to the GnRH‐7 protocol increased pregnancy rates to AI in heifers but not in nonlactating or lactating cows. [ABSTRACT FROM AUTHOR]

• Genotyping chips with 30 K markers are sufficient in detecting recent inbreeding events through runs of homozygosity. • Closed selection herds can maintain acceptable levels of inbreeding, since that mattings are conducted in a way that balances genetic variability and genetic progress. • The use of runs of homozygosity appears to be the optimal method for estimating inbreeding, as it provides information on haplotypes that are identical by descent. • A candidate gene (HTR1A) for docility identified in ROH islands is presented. The objective of this study was to compare the inbreeding coefficients estimated from pedigree data (F PED), traditionally used for internal monitoring by herds and breeding programs, with genomic estimates through the genomic relationship matrix (F GRM) and runs of homozygosity (F ROH). Besides, we used the genotype data to obtain the linkage disequilibrium (LD), population effective size (Ne), runs of homozygosity (ROH) islands and functional analysis of the genes presented in ROH islands. Male calves and sires from a closed Nellore herd (Lemgruber line) were genotyped with the Z-chip v2 (Neogen, Lincoln, Nebraska, USA) that contains approximately 30 thousand SNP markers. After quality control, 1088 animals and 21,351 SNPs remained for analysis. Runs of homozygosity (ROH) segments were identified in all analyzed animals, with an average number of 57.93 and average length of 2.95 Mb. We observed a higher occurrence of ROH up to 9 Mb, suggesting a proper mating scheme, which corroborate with LD and Ne analysis results. Estimates of F PED , F GRM and F ROH ranged from 0 to 0.2856, from 0.0705 to 0.3686 and from 0.0229 to 0.2762, respectively. Low to moderate correlations were observed between F PED and F GRM (0.17, P < 0.001); F PED and F ROH (0.20, P < 0.001) and F GRM and F ROH (0.92, P < 0.001). Nevertheless, considering our results we were successful in use runs of homozygosity for estimating autozygosity in a closed Nellore herd. Besides, from ROH islands, we were able to identify a candidate gene (HTR1A) for docility in this Nellore herd. [ABSTRACT FROM AUTHOR]

Pregnancy losses from fixed-time embryo transfer (FTET) to calving were evaluated in Bos indicus -influenced beef and dairy recipients. Data from 4366 FTET events were collected from Nelore × Angus recipient heifers, and from 38538 FTET events in Gir × Holstein recipient heifers and cows. In beef recipients, pregnancy losses were greater (P < 0.01) from FTET (day 7 of the experiment) to day 32 compared with day 32–100 and with day 100 to calving (58.7, 39.5, and 36.7%, respectively), and did not differ (P = 0.56) between these latter periods. Recipients that lost the pregnancy from FTET to day 32 gained less (P < 0.01) body condition score after FTET compared with recipients that maintained the pregnancy. Pregnancy losses from day 32 to calving were greater (P < 0.01) in recipients reared in drylots and moved to pastures on day 32 compared with recipients reared on pasture. In dairy recipients, pregnancy losses from FTET (day 7) to day 32 were greater (P < 0.01) than losses from day 32 to calving (50.4 and 29.4%). Pregnancy losses throughout gestation were greater (P < 0.01) when the FTET event was performed during the warm season, and greater (P < 0.01) in recipients with < 3/8 Gir influence. Recipients with ≥ 3/8 Gir influence experienced a lesser (P ≤ 0.05) increase in pregnancy losses during the warm season compared with recipients with < 3/8 Gir influence. Collectively, this experiment provides novel information about pregnancy losses in B. indicus -influenced herds receiving FTET. ● Pregnancy loss is a major reproductive challenge in beef and dairy systems. ● Timed embryo transfer allows evaluation of pregnancy losses throughout gestation. ● In both systems, most pregnancy losses occurred from early embryonic mortality. ● Late embryonic + fetal mortalities were also elevated and not related to diseases. ● Pregnancy losses in beef and dairy recipients were affected by management decisions. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the progesterone (P4) release profile provided by four commercially available intravaginal P4 devices, as well as the effect of circulating P4 concentrations exclusively from these devices on the development of the dominant follicle (DF) in Nelore (Bos indicus) cows. Therefore, non-lactating multiparous Nelore cows were enrolled in an experimental design, over three replicates, starting on Day −9 with the insertion of a reused P4 device (2 g – original P4 load) for 7 d, followed by two treatments of cloprostenol sodium (PGF; 0.482 mg), 24 h apart, on Days −3 and −2. Just before device removal, on Day −2, a norgestomet ear implant was inserted and, 2 d later (Day 0), at the time of norgestomet withdrawal, cows were randomly assigned to receive one of the intravaginal devices: Primer (0.5 g); Prociclar (0.75 g); Sincrogest (1 g); or CIDR (1.9 g), and 2 mg of estradiol benzoate (EB) im. Blood samples were collected immediately before P4 device insertion, 12 h later and daily over 15 d (1 d after P4 device removal). Ultrasound examinations were performed on Days 0, 7, 8, 9, 10, 12, and 14 to evaluate ovarian dynamics. Results are presented as mean ± SEM and differences were considered when P ≤ 0.05. Overall, the devices resulted in distinct circulating P4 concentrations over 10 d, varying according to their initial P4 load and P4 impregnated surface area. Primer provided the lowest circulating P4 concentrations over time, whereas, CIDR had the greatest concentration. Sincrogest and Prociclar were similar, producing intermediary circulating P4. There was no effect of treatment on the DF diameter on any specific day, nor on follicular growth rate from Day 7–10. However, the Primer device resulted in a greater mean DF diameter over time. Additionally, greater circulating P4 concentrations, mainly during the first 3 d of device insertion, were associated with smaller DF diameters regardless of the treatment. In conclusion, results from this study provided a better understanding of the P4 profile of intravaginal P4 devices, as well as, their effect on DF development in Bos indicus cows. These data contribute to optimize the use of P4 devices in the reproductive management of beef cattle. • Commercial P4 intravaginal devices provided different P4 profiles in Nelore cows. • P4 release capacity is influenced by the device's surface area and initial P4 load. • Lower circulating P4 concentrations resulted in a larger DF. • Lower circulating P4 during DF growth is desirable for Bos indicus. [ABSTRACT FROM AUTHOR]

Context: The use of crosses between Bos taurus and Bos indicus has boosted cattle production in tropical areas of Brazil, improving carcass and meat standards. However, there is little information on Canchim animals crossed with Nellore. Additionally, freezing is a preservation method frequently used by consumers, which allows meat to be preserved for a prolonged period, but little is known regarding this effect in meat frozen for 60 days from crossbred animals. Aims: The present study sought to evaluate the carcass performance and characteristics, and the effects of freezing prior to ageing on the meat of animals from different genetic groups finished in a feedlot. Methods: A total of 26 male cattle were used, consisting of Angus × Nellore (AAN), Canchim × Nellore (CAN) and Nellore (NEL), finished in feedlot. The carcasses were evaluated after slaughter. The steaks (Longissimus thoracis) were submitted to freezing for 0, 30 and 60 days before ageing, and were then aged for 1, 7 and 14 days. Key results: Consumption and performance was greater for AAN and CAN animals. The AAN and CAN crossbred cattle presented higher final liveweight, hot carcass weight, dressing-out percentage and rib eye area. Freezing did not affect the meat luminosity, and it reduced the shear force and the purge at 14 days of ageing when frozen for 30 and 60 days. Conclusions: The crossbreed between Canchim × Nellore animals is an alternative for termination in a feedlot. Meats frozen before ageing were more tender. Implications: Crossbred animals have better carcass performance and characteristics and the pre-freezing process yielded more tender meat. The Canchim is an alternative for crossing with pure Bos indicus animals. The use of breed crosses is an alternative for increasing animal production. For this purpose, breeds such as the Aberdeen Angus are already widely used, while Canchim animals present themselves as a viable alternative. Crossbred animals have better carcass characteristics and initial freezing for more than 30 days resulted in more tender meats. [ABSTRACT FROM AUTHOR]

Context: Livestock feed costs have a higher impact on the profitability of beef production systems and are directly related to feed efficiency. However, these traits are hard and have high costs to measure, reducing the availability of phenotypic records and reliability of genetic evaluations. Thus, the use of genomic information can increase the robustness of genetic studies that address them. Aims: The aim of the present study was to estimate genetic parameters for feed efficiency, growth, reproductive and carcass traits in Nelore cattle and the correlated response among them, using genomic information. Methods: Residual feed intake (RFI), dry-matter intake, feed conversion ratio, feed efficiency (FE), residual average daily gain (RG), residual feed intake and average daily gain (RIG), birthweight, weight at 120, 240, 365 and 450 days of age, scrotal circumference at 365 and 450 days of age, rib-eye area, backfat thickness and rump fat thickness were evaluated. The genetic parameters were estimated using the single-step genomic best linear unbiased prediction approach. Key results: The FE-related traits showed low to moderate heritability ranging from 0.07 to 0.23. Feed efficiency-related traits showed low genetic correlations with reproductive (–0.24 to 0.27), carcass (–0.17 to 0.27) and growth (–0.19 to 0.24) traits, except for growth with dry-matter intake (0.32–0.56) and weight at 365 days of age with FE (–0.40). Conclusions: The selection to improve growth, reproductive and carcass traits would not change RFI, RG and RIG. The choice of the most adequate selection criterion depends on the production system, that is, RFI might be used for low-input beef cattle systems, and RIG would be used for more intensive and without-any-dietary-restrictions beef cattle systems. Implications: The estimates of heritability and genetic correlations suggest that genetic selection for feed efficiency using RFI, RG and RIG in Nellore cattle leads to higher genetic gain than does that using FE and feed conversion ratio without affecting other profitability traits. Although the economic and environmental importance of feed efficiency traits, the genetic selection has been little used as a selection criterion in zebu breeding programs. The inclusion of genomic information could improve the reliability of genetic parameters, which is fundamental for their adoption as a large-scale selection criterion. Traits such as residual feed intake, residual average daily gain and residual intake and average daily gain can be used for genetic selection for feed efficiency, without affecting other profitability traits. [ABSTRACT FROM AUTHOR]

Context: Nitrate salts can be utilised by the rumen bacteria as a nitrogen source. Nitrate salts can induce a methaemoglobinaemia in cattle if consumed in sufficient quantities. Methaemoglobinaemia is the principal factor that leads to the onset of clinical signs for nitrate toxicity in cattle. A methaemoglobin concentration ≥20% is considered unsafe for cattle. There are, however, limited studies on the longer-term effects of nitrate supplementation on methaemoglobin formation in Bos indicus steers consuming forage that is reflective of northern Australia's poor quality, native pasture in the dry season. Aims: We hypothesised that the Australian government's recommended daily dose of nitrate salts given to Bos indicus cattle would not cause a methaemoglobinaemia in the blood >20% throughout a 70 day treatment period. Methods: A 70 day study was conducted to determine the methaemoglobin, carboxyhaemoglobin, total haemoglobin, growth rate and forage intakes of cattle supplemented with a non-protein-nitrogen treatment containing nitrate (6.48 g NO3/kg dry matter intake (DMI) or no nitrate and consuming a chaffed Flinders grass hay (Iseilema spp.), a C4 species. The dose rate of nitrate was selected to match the Australian government guidelines. Ten 3-year-old fistulated Bos indicus steers (mean liveweight ± s.d., 400.7 ± 26.2 kg) were randomly allocated into two groups (n = 5). Blood samples were collected at 0, 2, 4 and 6 h after treatment with nitrate or no nitrate on days 10, 30, 50 and 70 to measure haemoglobin fractions in the blood. Key Results: Nitrate treatment caused the mean methaemoglobin (P < 0.001), peak methaemoglobin (P < 0.001) and carboxyhaemoglobin (P = 0.008) concentration to be greater in the blood of steers compared with steers given no nitrate. Nitrate treatment had no general effect on the total haemoglobin, DMI or bodyweight of steers. Conclusions: Bos indicus steers treated with 6.48 g NO3/kg DMI develop a methaemoglobinaemia that does not exceed 20% of total haemoglobin for 70 days. This data supports the Australian government's recommended feeding rate of nitrate to sedentary Bos indicus steers. Implications: The Australian government's method for feeding nitrate to cattle is safe under the conditions of this study. Within the conditions of the study, Bos indicus steers treated with nitrate develop a methaemoglobinaemia that does not exceed 20% of total haemoglobin for 70 days. Although the data in the current study supports the Australian government's recommended dose rate as safe for cattle the data represents Bos indicus steers in a sedentary state. Further research is required to validate the dose rate of nitrate for cattle in an active state. [ABSTRACT FROM AUTHOR]

The influence of sex and reciprocal cross type were evaluated in Brahman-sired (B × A) and Angussired (A × B) F1 cattle following modified-live viral vaccination regarding virus neutralization titers (VNT) and cell-mediated immune (CMI) responses following in vitro exposure to Bovine Viral Diarrhea Virus (BVDV) Type 1 (BVDV1) and Type 2 (BVDV2) genotypes. VNT against BVDV were based on virus neutralization assay, and CMI responses were measured using the PrimeFlow mRNA assay for determination of the frequency of BVDV and interferon-gamma (IFN-γ) positive cells. Mixed model procedures utilized individual calf ID as a random effect with fixed effects of F1 cross type, calf sex, evaluation date, and potential 2-way interactions; models for frequency of BVDV and IFN-γ positive cells, stimulation conditions (BVDV1, BVDV2, mitogen, none) and potential two-way and three-way interactions of fixed effects. Relationships of immune responses with calf birth weight and weaning weight and steer carcass traits were also investigated. This study found several CMI traits differed due to the type of cross and calf sex; however, no differences in VNT were attributed to these effects. Cells from B × A animals consistently ranked approximately 20% greater for BVDV positive cells (BVDV+) than those from A × B animals pre-MLV vaccination; however, post-MLV vaccination, cells from A × B animals ranked 20% greater (P < 0.05) for CD2+, CD4+, and CD8+ cells. Post-MLV steers consistently had 30 to 35% greater (P < 0.05) frequencies of BVDV+ cells following viral exposure; steers had greater frequencies (P < 0.05) of CD4+ and CD335+ cells expressing IFN-γ and ranked greater for CD2+ and CD8+ cells when compared with heifers in both crosses. Only vaccination timing affected BVDV VNT. No significant correlations involving VNT and CMI responses were observed among A × B animals when stimulated with BVDV1, but among B × A animals, positive correlations were observed with IFN-γ in CD4+ (r = 0.406, P = 0.049) and CD335+ (r = 0.472, P = 0.020). When stimulated with BVDV2, positive correlations of 0.33 to 0.39 (P < 0.05) were observed between BVDV and IFN-γ frequency within cell type; these were not significant when stimulated with BVDV1, except for CD335+ cells (r = 0.41, P = 0.003). No correlations for VNT and CMI responses were observed when stimulated with BVDV2. No major correlations between immune responses and weight or carcass traits were observed, and immune response category for BVDV or IFN-γ frequency did not influence birth weight or weaning weight. Differences in CMI responses involving reciprocal cross types and sex observed in this project may relate to widely reported reciprocal cross differences in birth weight in Bos indicus - Bos taurus crossbred cattle and warrant additional study. [ABSTRACT FROM AUTHOR]

Candidate gene approach facilitates searching causative polymorphisms that influence quantitative traits. Biosynthesis of estrogen catalyzed by aromatase, a product of the CYP19 gene affect lactogenesis. The objective of the study was to determine the polymorphism in the promoter region of CYP19 gene by PCR-RFLP and was undertaken on 502 bovine species belonging to Ongole (Bos indicus), Holstein Friesian crossbred, Jersey crossbred cattle, and Murrah buffaloes reared across Southern India. The frequency of the CYP19A allele was 0.90, 0.88, and 0.77 in Jersey crossbred, HF crossbred, and Ongole cattle, respectively. The BB genotypes could not be observed in Jersey crossbred cattle. Fixation of the B allele was evident in Murrah buffaloes. The Hardy-Weinberg equilibrium was verified and general linear model procedure was adopted to evaluate the effect of CYP19/PvuII genotype on milk production traits. The AA genotypes (2111.53 ± 51.84 kg) in Jersey crossbred cattle, AB genotypes (2529.00 ± 238.08 kg) in Holstein Friesian crossbred and BB genotype (590.85 ± 92.29 kg) in Ongole cattle yielded more milk. The fat content of milk in AB genotypes was higher in all the cattle. The solid-not-fat and lactose content was more in the milk of BB genotypes and protein in AB genotypes of Ongole cattle. The fat, SNF, protein, and lactose content in Murrah buffalo milk was 7.26 ± 0.62%, 9.20 ± 0.19%, 3.44 ± 0.06%, 4.87 ± 0.11%, respectively. No significant (p > 0.05) effect of CYP19/PvuII genotypes on milk production and composition was found in any of the genetic groups studied. The sequence analysis of CYP19 P 1.1 revealed additional SNPs in all the cattle under study. A novel SNP at 82 nucleotides upstream of the PvuII restriction site was observed in Murrah buffaloes. [ABSTRACT FROM AUTHOR]

Context: Transportation, a common practice in cattle production, activates the hypothalamo-pituitary-adrenal (HPA) axis, ultimately increasing glucocorticoids and altering the cellular immune system in cattle. Oxytocin attenuates the HPA axis in mammals. Intra-nasal oxytocin supplementation has been investigated in human and rodent models, revealing anxiolytic effects. The aim of this study was to assess the ability of exogenous oxytocin to mitigate stress and inflammatory responses in transported cattle. Aims: We hypothesised that Bos indicus cattle treated with intra-nasal oxytocin would demonstrate more stable cortisol and inflammatory responses when subjected to handling and 6 h of road transportation compared with cattle treated with intra-nasal saline. Methods: Thirty, Bos indicus steers were allocated to one of three treatments: (1) intra-nasal sterile saline and held in the yard for 6 h (S-NT; n = 10), (2) intra-nasal sterile saline and transported for 6 h (S-T; n = 10), and (3) intra-nasal oxytocin (0.3 IU/kg bodyweight) and transported for 6 h (OXT-T; n = 10). Blood was collected at 0, 6, 48, and 72 h and analysed for haematological parameters, cortisol, glucose and lactate. Key results: A treatment × time effect (P < 0.05) was detected for lymphocytes and basophils, such that oxytocin helped maintain baseline counts. A treatment × time effect was detected for neutrophils and eosinophils such that counts were greater and lesser, respectively, directly following transport (P < 0.01) for transported treatments. Total leukocyte counts were not different between treatments (P = 0.96). No differences were observed between treatments or over time for plasma cortisol concentration (P = 0.46). A treatment × time interaction (P < 0.03) was detected for bodyweight such that transportation, independent of intra-nasal treatment, resulted in increased weight loss compared with the non-transported treatment. Conclusion: Oxytocin altered circulating basophils in Bos indicus cattle exposed to short-duration transport. Although no effect on the HPA axis was detected via changes in cortisol concentration, road transport induced some signs of an acute inflammatory response directly following transportation. Implications: Providing exogenous oxytocin improved the maintenance and recovery of some cellular immune system parameters in Bos indicus steers subject to short duration transport and more research is needed to explicate a more comprehensive understanding of such effects. Transportation activates the stress axis in beef cattle and may compromise the immune system leading to increased morbidity. Oxytocin has been demonstrated to attenuate the stress axis in humans and rodents and may be useful in transported cattle to decrease the stress axis and thereby confer improved immune protection. Although the present study did not detect effects of oxytocin on the stress response via changes in cortisol concentration, providing exogenous oxytocin improved the recovery of some cellular immune system parameters in Bos indicus steers subject to short duration transport. Additional research is needed to explicate a more complete understanding of such effects. [ABSTRACT FROM AUTHOR]

The major histocompatibility complex (MHC) contains many genes that play key roles in initiating and regulating immune responses. This includes the polymorphic MHCI and MHCII genes that present epitopes to CD8+ and CD4+ T‐cells, respectively. Consequently, the characterisation of the repertoire of MHC genes is an important component of improving our understanding of the genetic variation that determines the outcomes of immune responses. In cattle, MHC (BoLA) research has predominantly focused on Holstein‐Friesian animals (as the most economically important breed globally), although the development of high‐throughput approaches has allowed the BoLA‐DRB3 repertoire to be studied in a greater variety of breeds. In a previous study we reported on the development of a MiSeq‐based method to enable high‐throughput and high‐resolution analysis of bovine MHCI repertoires. Herein, we report on the expansion of this methodology to incorporate analysis of the BoLA‐DRB3 and its application to analyse MHC diversity in a large cohort of cattle from Brazil (>500 animals), including representatives from the three major Bos indicus breeds present in Brazil – Guzerat, Gir and Nelore. This large‐scale description of paired MHCI‐DRB3 repertoires in Bos indicus cattle has identified a small number of novel DRB3 alleles, a large number of novel MHCI alleles and haplotypes, and provided novel insights into MHCI‐MHCII association ‐ further expanding our knowledge of bovine MHC diversity. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to evaluate the effect of pre-synchronization with progesterone (P4) for 3 and 6 days in Nelore cows in postpartum anestrus period, submitted to a fixed-time artificial insemination program (FTAI). Materials and methods: Seventy-four multiparous Nelore cows with a body condition of 2.5 were used. The cows were submitted to three experimental groups, control group and groups pre-synchronized with P4 for a period of 3 and 6 days. For the determination of postpartum anestrus status, ultrasound scans and blood samples were taken to verify the absence of endogenous P4. Forty-five days after AI, gestation was diagnosed. Data were obtained by descriptive analysis and in the case of presentation of significant differences the Chi-square test was used, considering a frequency of P < 0.05. Results: A higher gestation rate was observed for the group that was pre-synchronized for three days with P4 (40 %), in relation to the groups of six days of pre-synchronization and control (25 % and 32 %, respectively). Conclusion: It is possible to conclude that the pre-synchronization with P4 for three days improved the gestation rate of Nelore cows in the postpartum anestrus period. [ABSTRACT FROM AUTHOR]

Sports genomics is considered a branch of molecular genetics, which is used to identify the candidate genes associated with domestic animals' sporting traits, especially in horses, dogs, and cattle, to select animals with the best sporting ability. Blood samples were collected from indigenous bulls (n=233) used for a sporting event in Tamil Nadu for genomic DNA isolation. Molecular characterization of Myostatin gene, including its promoter region, was carried out to find the sequence variation. Compared with the Bos indicus sequence, two variations were detected in exon 1 and exon 3 and no variation in exon 2. The intronic regions were found to have single base pair variations, single base-pair insertions, and 12 to 16 bp insertions. In addition, nine types of variations found in the promotor region and the genotyping of SNP at position -644 revealed the predominance of genotype CC with the estimated frequencies of 0.81, 0.69, 1.00, and 0.80 in Pulikulam, Kangayam, Umblachery, and non-descript bulls, respectively. TT genotype had higher mean velocity and highest time spent within the boundary of bull tamers, and CC genotype had higher stride length. In conclusion, it could be inferred that the Myostatin gene would be used as a marker for sporting traits, but it needs extensive study to validate its role in regulating sporting traits. [ABSTRACT FROM AUTHOR]

This study evaluated the possible effects of sire and dam calving groups on age at first calving in Brahman heifers. A total of 570 heifers born between the years 2004 and 2017 were exposed as yearlings to fertile bulls through time of pregnancy determination. A calving group was determined by calculating the mean (993 d) and standard deviation (187 d) of heifer age at first calving. Heifers considered to calve early (≤899 d; calving group = 1) or late (≥1087 d; calving group = 3) were at least half a standard deviation (94 d) away from the mean. All other heifers were considered to have an intermediate age at first calving (900–1086 d; calving group = 2). Of the 570 heifers, only heifers from a dam (n = 182) with a known age at first calving and from a sire (n = 35) with 5 or more daughters were kept to determine the effect of dam calving group and the effect of sire calving group on age at first calving and calving group in daughters, resulting in a total of 284 heifers available for analysis. Variables included were dam and sire calving groups of the heifer, heifer age at first calving, heifer calving group, heifer season of birth, and heifer year of birth. Data were analyzed using the GLM procedure s of SAS and proportions were tested using Chi-square. Sire calving group did affect (P < 0.01) age at first calving and calving group in heifers, but dam calving group did not affect (P > 0.10) daughter age at first calving or calving group. Analysis of dam calving group and sire calving group effects identified a year of birth effect (P < 0.01) on daughter age at first calving and calving group, whereas there was no significant season of birth effect. The proportion of daughters calving early for sire calving groups differed significantly from the expected proportion (P < 0.01), whereas the proportion of daughters calving early for dam calving groups did not differ. An effort to produce a greater proportion of Brahman heifers capable of calving early will not be effective from the dam side but may be effective from the sire side. • Bos indicus breeds reach puberty and calve at older ages. • Age at first calving was affected by sire calving group but not dam calving group. • Sire influences the proportion of Brahman heifers calving at 2 years of age. [ABSTRACT FROM AUTHOR]

The study was conducted to determine the health status of hariana cattle in different seasons in breeding tract of haryana cattle. Health status of hariana 240 cattle has been studied in field condition in terms of BCS, Physiological Parameters, Hematological Parameters, Helminthic And Tick Infestation in Relation with Season. The mean of body condition score was significantly lower (P<0.05) during summer and rainy season compared to winter. whereas, pulse rate, respiration rate and rectal temperature were significantly higher during summer and rainy seasons compared to winter. Haemoglobin (HB), White blood cells (WBC) and Red blood cells (RBC) Counts were significantly lower during rainy and winter season as compared to the summer season. wbc varied significantly amongst all the season. The percent (%) prevalence of tick infestation in hariana cattle in summer, winter and rainy seasons were 18.75, 16.25 and 27.50 Respectively. The samples were also found to be positive for prevalence of Strongyles, Paramphistomes, Faciola gigantica, Moniezia expansa and Buxtonella sulcata in hariana cattle in all seasons. The observations of the present study would provide a basis for evolving effective control strategy for management of health status of hariana cattle in its breeding tract. Higher during summer and rainy seasons compared to winter. HB, WBC AND RBC Counts were significantly lower during rainy and winter seasons as compared to the summer season, whereas it was the highest during summer. WBC varied significantly amongst all the seasons. The percent (%) prevalence of tick infestation in hariana cattle in summer, winter and rainy seasons were 18.75, 16.25 and 27.50, Respectively. The samples were also found to be positive for prevalence of Strongyles (Nematodes), Paramphistomes, Faciola gigantica, Moniezia expansa and buxtonella sulcata in hariana cattle in summer, winter and rainy seasons. The observations of the present study would provide a basis for evolving effective control strategy for the management of health status of hariana cattle in its breeding tract. [ABSTRACT FROM AUTHOR]

The effect of Alpha-lipoic acid (ALA) on lipid peroxidation, catalase activity and post-thaw semen quality of Achai bulls (Bos indicus) was studied. Semen samples (n=28), collected from adult Achai bulls (n=4) at weekly intervals, were diluted with Tris-citric acid egg yolk extender having various concentrations of ALA (0.00, 0.25, 0.50, 1.00 and 2.00mM) and frozen in liquid nitrogen (-196ºC). Post-thaw semen assessment revealed that the lipid peroxidation decreased, while catalase activity increased (P<0.05) in all extenders containing ALA as compared to control, except in extender containing 2.00mM in which catalase activity decreased (P > 0.05) than control. Moreover, post-thaw semen quality parameters i.e., sperm viability and plasma membrane integrity were higher (P<0.05) in extender having 0.25 and 0.50 mM ALA compared to control, whereas mitochondrial membrane potential was significantly improved only with 0.50mM ALA as compared to control and all other ALA concentrations used. However, acrosome and DNA integrity of spermatozoa increased in extender supplemented with 0.25, 0.50 and 1.00mM ALA (P<0.05) compared to control. Computer Assisted Semen Analysis (CASA) of post-thaw semen revealed that total motility (%) and curvilinear velocity (µm/s), progressive motility (%), progressive fast motility (%) and beat cross frequency (Hz), and straight-line velocity (µm/s) and average path velocity (µm/s) were higher (P < 0.05) for 0.50 and 1.00mM, 0.25 and 0.50mM and 0.50 and 2.00mM ALA concentrations, respectively, than control. In conclusion, the addition of 0.50mM ALA in Tris-citric acid, fructose, egg yolk glycerol extender can perform optimum among all ALA concentrations (0.00, 0.25, 1.00 and 2.00mM) used, in terms of minimizing the oxidative stress and improving the post-thaw semen quality of Achai bulls. [ABSTRACT FROM AUTHOR]

Objective. To compare the reproductive performance of postpartum and open Bos indicus cows and to study the cost effectiveness of retaining non-pregnant animals after a short breeding season in tropical region of Mexico. Material and Methods. A total of 128 Bos indicus were included, 87 postpartum cows (PP) with ≤90 days after calving and 41 open cows (OC) with >90 days open. The study was divided into three phases: 1) Estrus synchronization followed by FTAI (day 0-10), 2) Estrus detection and AI (day 11-45) and 3) Natural mating (day 46-90). For the first phase, all animals were synchronized and AI at fixed time (day 10). Cows displaying overt signs of estrus (day 11-45) were AI. Open cows during the previous two phases were exposed to the bull. Results. Pregnancy in phase 1 was different (p<0.01) for PP and OC groups, 58.6% and 34.1%, respectively. Overall pregnancy percentage over the second service was 42.5% (p>0.05). No differences (p>0.05) were observed at phase 3, average 44.2%. By the end of the breeding season, the cost of OC, was 3 times more expensive than PP cows. Conclusions. Pregnancy rate at first phase was higher in PP cows than OC cows. At the end of breeding season, a pregnancy rate of 80% was found. Incorporation of open cows from previous breeding season was more expensive than PP cows in all phases of the breeding program. Retaining an open cow for rebreeding one year or more could not be economically feasible. [ABSTRACT FROM AUTHOR]