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The present study aimed to assess the occurrence of cytological endometritis (CYTO), a nonsymptomatic inflammation of the endometrium, at first artificial insemination (AI) postpartum in Norwegian Red cows. Further, risk factors for CYTO manifestation and its effect on reproductive success and late embryo loss were evaluated. In total 1,648 cows located in 116 herds were included in the study. On mainly spontaneous estrus, endometrial cytology samples were collected using a cytotape technique, and a total of 300 representative epithelial cells and polymorphonuclear neutrophils (PMN) were counted at 400× magnification. Vaginal mucus obtained by Metricheck (Simcro) and body condition score were recorded. Milk samples for progesterone analysis were collected at AI and 21 d later. Pregnancy was diagnosed by rectal palpation or analysis of pregnancy-associated glycoproteins. Based on the constructions of a receiver operator characteristics curve, the cut-off level for PMN defined as CYTO was set to 3.0%, representing the level at which the PMN occurrence affected pregnancy outcome, with the highest summation of sensitivity (32.4%) and specificity (74.9%). Three logistic models with herd included as random factor were constructed. The outcome for the first model was the likelihood for CYTO based on the endometrial samples, in the second model pregnancy to first AI, and in the third model embryo loss. The proportion of CYTO was 28.0% (461/1,648). The average interval in days to first AI was 71.7 d (standard error ± 0.7) and the overall pregnancy incidence to first AI was 59.8% (866/1,449). The likelihood for CYTO at first AI was associated with AI personnel, calving to first AI interval, vaginal mucus characteristics, amount of red blood cells in sample, season, and barn type. Pregnancy to first AI was lower in CYTO-positive cows (odds ratio = 1.51, confidence interval = 1.17–1.94). Other factors affecting pregnancy to first AI were AI personnel, test day milk yield, barn type, and obstetrical conditions or fertility treatments before first AI. The proportion of late embryo loss and abortion was 8.6% (82/948) and 2.8% (24/866), respectively. Late embryo loss was associated with treatment against fertility disorders before first AI, but not associated with CYTO. Overall, our results suggest that even if Norwegian Red cows show a fairly high prevalence of CYTO in the endometrium at first AI, it does not seem to have a major effect on the reproductive performance. The Norwegian Red breeding program has emphasized fertility and health for decades, and a genetically advantageous uterine immunology might be one of the preserved mechanisms.

Ukrainian Red- and Black-and-White dairy breeds, which are the most common in the region, as well as each biological system, are in constant variability and need constant scientifically-based support and improvement not only in general milk productivity, but also in such specific features as duration of economic use and reproducibility. A systematic approach in the optimization of breeding programs and the search for optimal crossbreeding options in populations of domestic dairy breeds is a little-studied and relevant area of research. The aim of the research is to study the peculiarities of the formation of the exterior of the first-born cows obtained from bulls of the Montbeliard, Norwegian Red and Holstein breeds. Materials and methods of research. The research was conducted in 2019–2020 on the basis of 4 breeding farms of Cherkasy region. 120 heads of first-born cows of Ukrainian Black-and-White dairy breeds, 201 heads of Ukrainian Red-and-White dairy breeds, 80 heads of first-generation Ukrainian Red-and-White dairy breeds and Montbeliards, 96 heads of first-generation Ukrainian Black-and-White dairy breeds and Norwegian Black-and-White cows were taken into account. Comparative evaluation of animals on productive traits, exterior type was carried out within breeding herds, taking into account the structure of the genotype of animals. The study of morphological and physiological features of the udder of cows was carried out by determining the shape and size by taking measurements at 2–3 months of lactation for 1 hour. 30 min before milking. The functional properties of the udder were studied by the intensity of milk production (kg/min.) during the control milking. The milk yield was determined by the formula proposed by N. P. Pogribna and others. The growth intensity of repair heifers and the index of decline in growth energy were determined by the methods of Yu. K. Svechin, L. I. Dunaev, V. P. Kovalenko. Biometric processing of experimental data – statistical, correlation and analysis of variance were performed according to the methods of N. A. Plokhinsky and E. K. Mercury on a computer type IBM PC/AT. Research results. At the age of six months among local heifers obtained from breeders of the Montbeliard Breed received a live weight of more than 200 kg (when using Holstein Breeders for reproduction, the weight of heifers at 6 months was 174.4–182.1 kg), at the age of over 380 kg (383.5–384.8 kg), in 15 months over 440 kg (442.9–449.9 kg). From birth to 6 months of age, heifers of the Ukrainian Black-and-White dairy breed obtained from Holstein Breeders had a higher live weight compared to crossbreeds obtained from bulls of the Norwegian Breed. After 6 months of age, local heifers outnumbered their peers in terms of live weight with an unlikely difference. The first-born cows of the Ukrainian Red-and-White dairy breed had high growth rates with well-developed breasts in depth, width and girth: height at withers and buttocks, respectively 133.7 ± 0.96 cm and 136.1 ± 1.05 cm with well-developed chest depth (72.9 ± 1.17 cm), width 42.6 ± 2.18 cm) and girth 193.0 ± 1.54 cm), with a wide back in the macula 51.6 ± 3.77 sm and in the buttocks 35.2 ± 1.09 sm. Body measurements of local first-borns of genotype 1/2URW1/2M – only 80 heads: height at withers 124.7 ± 3.71 cm (below first-borns obtained from Holstein bulls by 9.0 sm (P > 0.95) URW); in the buttocks 127.9 ± 2.19 sm (8.2 sm below the firstborn URW breed) (P > 0.99), oblique body length 158.3 ± 13.82 cm (4.6 cm below the firstborn URW breed)). However, they outnumbered the first-borns obtained from Holstein bulls by measuring the depth of the breast 75.3 ± 3.11 cm (2.4 cm), breast width from 47.7 ± 2.40 cm (5.1 sm), chest circumference 205.0 ± 4 10 sm (12 sm (P > 0.99)), width of the buttocks in the macula and buttocks (6.1–3.1 sm (P > 0.95)). The first-born cows of the Ukrainian Black- and-White dairy breed obtained from Holstein breeders had a height at the withers and buttocks of 130.9 ± 1.22 cm and 137.2 ± 0.86 cm, respectively, with well-developed breasts in depth and girth. Local first-borns obtained from the selection of Ukrainian Black-and-White dairy cows of Norwegian Black-and-White breeders had no significant difference in basic body measurements with those of the same age as those obtained from Holstein breeders. Regardless of genotype and breed, the udder of first-born cows is large in volume (in girth – 128.6 ± 3.14 and 148.7 ± 2.66 sm, length – 35.1 ± 1.23 and 40.3 ± 1.55 sm and a width of 29.5 ± 3.26 and 33.8 ± 4.36 sm.) With proportionally developed parts of the udder, bath- or cup-shaped, firmly attached to the abdominal wall with cylindrical teats. Duration of milking 10.1 ± 0.167 – 12.2 ± 0.157 minutes, milk production rate 1.90 ± 0.01 – 2.50 ± 0.07 kg/min. It was found that with increasing daily milk yield, the intensity of milk production also increased: correlation coefficients (r = 0.439–0.577) have a high reliability (td = 3.97–7.58). The value of the udder index among the studied breeds and genotypes was different and ranged from 43.4 ± 0.06% to 45.2 ± 0.02%. Conclusions. The crossing of Ukrainian Black-and-White dairy cows with Norwegian Black-and-White breeders did not have a significant effect on the exterior type of repair heifers under 12 months of age. Crossbreeding with the Montbeliard breed made it possible to obtain heifers that were inferior in growth, but had a developed, three-dimensional body, chest and pelvis. The use of genetic material of the Montbeliard and Norwegian Black-and-White breeds has contributed to the formation of cows of the desired exterior type with good udder characteristics that meet modern requirements of machine mil.

Soybean meal is one of the most important protein sources in concentrate feeds for dairy cows. The objective of the present study was to provide knowledge on the effects of using a novel yeast microbial protein source (Candida utilis) in concentrate feed for dairy cows on the production and quality of a Gouda-type cheese. Forty-eight Norwegian Red dairy cows in early to mid lactation were fed a basal diet of grass silage, which was supplemented with 3 different concentrate feeds. The protein source of the concentrates was based on conventional soybean meal (SBM), novel yeast (C. utilis; YEA), or barley (BAR; used as negative control because barley has a lower protein content). The experiment was carried out for a period of 10 wk, with the first 2 wk as an adaptation period where all dairy cows were fed grass silage and the SBM concentrate. The cows were then randomly allocated to 1 of the 3 different compound feeds: SBM, yeast, or barley. Cheeses were made during wk 8 and 9 of the experiment, with 4 batches of cheese made from milk from each of the 3 groups. The cheeses made from milk from cows fed SBM concentrate (SBM cheese) had a higher content of dl-pyroglutamic acid and free amino acids than the other cheeses, indicating a faster ripening in the SBM cheeses. Despite these differences, the sensory properties, the microbiota, and the Lactococcus population at 15 wk of ripening were not significantly different between the cheeses. This experiment showed that although the raw materials used in the concentrate feed clearly influenced the ripening of the cheeses, this did not affect cheese quality. Yeast (C. utilis) as a protein source in concentrate feed for dairy cows can be used as a replacement for soybean meal without compromising the quality of Norwegian Gouda-type cheeses.

Lactation yield estimates standardized to common lactation lengths of 270-d or 305-d equivalents are commonly used in management decision support tools and dairy cow genetic evaluations. The use of such measurements to quantify the (genetic) merit of individual cows fails to penalize cows that do not reach the standardized lactation length, or indeed reward cows that lactate for more than the standardized lactation length. The objective of the present study was to quantify the genetic and nongenetic factors associated with lactation length in seasonal-calving, pasture-based dairy cows. A total of 616,350 lactation length records from 285,598 Irish cows were used. Linear mixed models were used to quantify the associations between lactation length and calving month, parity, age at calving, previous dry period length, calving difficulty score, heterosis, recombination loss, breed, and herd size, as well as to estimate the genetic and residual variance components of lactation length. The median lactation length in the edited data set was 288 d, with 27% of cows achieving lactations of at least 305 d. Relative to cows calving in January, the lactations of cow calving in February, March, or April was, on average, 4.2, 12.7, and 21.9 d shorter, respectively. The lactation length of a first parity cow was, on average, 7.8, 8.6, and 8.4 d shorter than that of second, third, and fourth parity cows, respectively. Norwegian Red and Montbéliarde cows had, on average, a 4.7- and 1.6-d shorter lactation than Holstein-Friesian cows, respectively. The heritability estimate, coefficient of genetic variation, and repeatability estimate of lactation length were 0.02, 1.2%, and 0.04, respectively. Based on the genetic standard deviation for lactation length estimated in the present study (3.3 d), cows ranked in the top 20% for genetic merit for lactation length would be expected to have lactations 9.2 d longer than cows in the bottom 20%, demonstrating exploitable genetic variability. Given the vast array of genetic and nongenetic factors associated with lactation length, an approach which combines improved management practices and selective breeding may be an efficient and effective strategy to lengthen lactations.

Submitted 2020-07-17 | Accepted 2020-08-18 | Available 2020-12-01 https://doi.org/10.15414/afz.2020.23.mi-fpap.250-257 This study aimed to evaluate the score for subclinical ketosis risk, which is routinely monitored in Czech Holstein cows. The score is based on milk recording indicator traits which include fat-to-protein ratio, fat-to-lactose ratio, citric acid, β-hydroxybutyrate, and acetone concentrations. The score was significantly (P

Submitted 2020-07-26 | Accepted 2020-09-02 | Available 2020-12-01 https://doi.org/10.15414/afz.2020.23.mi-fpap.313-318 The increase of milk production at the farm level requires an accurate balancing of the diet and the nitrogen supply also to minimise the possible environmental pollution deriving from dairy farming. The aim of this study was to evaluate dietary protein utilization at different crude protein (CP) levels and to predict nitrogen content in faeces on the basis of nutritional parameters and milk urea nitrogen content (MUN, mg dL -1 ). The study was conducted on three groups (A, B, C) of lactating dairy cows (8 cows per group, including Latvian Brown and Holstein Black and White breeds) from 10 to 30 days in milk. Total mixed rations containing different levels of CP (approximately 18.0%, 17.5% and 17.0% for A, B and C, respectively) were fed. The amount of feed consumed by each cow was measured and feed samples collected during the trial. Milk yield (kg d-1 -1 ) and faeces amount were recorded, and samples were collected at day 21 of the study for further analysis. Feed samples were analysed for CP, net energy for lactation (NEL, MJ kg -1 ) and other parameters. Milk samples were analysed for fat (%), total protein (%), casein (%) and urea content (mg dL -1 ). The statistical investigation was conducted using ANOVA, and correlation and regression analyses. The results showed that milk yield, fat, total protein, casein, urea, and MUN were not significantly different among groups being not affected by the dietary CP levels. The correlation between faecal nitrogen content and CP content in feed was moderately positive and statistically significant (r=0.44, P=0.03), while the correlation between faecal nitrogen content and MUN was moderately negative and showed tendency towards significance (r=-0.39, P=0.06). The regression analysis showed that feed CP explained approximately 20% of faeces nitrogen content. Keywords: dairy cow, milk urea, faeces nitrogen, feed crude protein References Amanlou, H., Farahani, T. A. and Farsuni, N. E. (2017). Effects of rumen undegradable protein supplementation on productive performance and indicators of protein and energy metabolism in Holstein fresh cows. Journal of Dairy Science, 100, 3628-3640. https://doi.org/10.3168/jds.2016-11794 J. A. D. R. N., Judy, J. V., Kebreab, E. and Kononoff, P. J. (2016). Prediction of drinking water intake by dairy cows. Journal of Dairy Science, 99, 7191–7205. https://doi.org/10.3168/jds.2016-10950 Arunvipas, P., VanLeeuwen, J. A., Dohoo, I. R., Keefe, G. P., Burton, S. A. and Lissemore, K. D. (2008). Relationships among milk urea-nitrogen, dietary parameters and fecal nitrogen in commercial dairy herds. Canadian Journal of Veterinary Research, 72, 449-453. Bijgaart, H. van den. (2003). Urea. New applications of mid-infra-red spectrometry. Bulletin of IDF, 383, 5-15. Broderick, G. and Huhtanen, P. (2020). Application of milk urea nitrogen values. Retrieved on June 30, 2020 from https://naldc.nal.usda.gov/download/15797/PDF Bucholtz, H., Johnson, T. and Eastridge, M. L. (2007). Use of milk urea nitrogen in herd management. In: Tri–State Dairy Nutrition Conference. Proceedings. Ft. Wayne, Indiana, p. 63-67. Colmenero, J. J. O. and Broderick, G. A. (2006). Effect of dietary crude protein concentration on milk production and nitrogen utilization in lactating dairy cows. Journal of Dairy Science, 89, 1704-1712. https://doi.org/10.3168/jds.S0022-0302(06)72238-X Dijkstra, J., Oenema, O. and Bannink, A. (2011). Dietary strategies to reduce N excretion from cattle: implications for methane emissions. Current Opinion in Environmental Sustainability, 3, 414-422. https://doi.org/10.1016/j.cosust.2011.07.008 Kalscheur, K. F., Vandersall, J. H., Erdman, R. A., Kohn, R. A. and Russek-Cohen, E. (1999). Effects of dietary crude protein concentration and degradability on milk production responses of early, mid, and late lactation dairy cows. Journal of Dairy Science, 82, 545-554. https://doi.org/10.3168/jds.S0022-0302(99)75266-5 Kidane, A., Overland, M., Mydland, L. T. and Prestlokken, E. (2018). Interaction between feed use efficiency and level of dietary crude protein on enteric methane emission and apparent nitrogen use efficiency with Norwegian Red dairy cows. Journal of Animal Science, 96, 3967–3982. https://doi.org/10.1093/jas/sky256 LVS. (2004). Soil improvers and growing media - Determination of nitrogen - Part 1: Modified Kjeldahl method. Latvian standard, Riga, Latvia. LVS. (2008). Soil improvers and growing media - Sample preparation for chemical and physical tests, determination of dry matter content, moisture content and laboratory compacted bulk density. Latvian standard, Riga, Latvia. Ng-Kwai-Hang, K. F., Hayes, J. F., Moxley J. E. and Monardes, H. G. (1985). Percentages of protein and nonprotein nitrogen with varying fat and somatic cells in bovine milk. Journal of Dairy Science, 68, 1257-1262. https://doi.org/10.3168/jds.s0022-0302(85)80954-1 NRC. (2001). Nutrient Requirements of Dairy Cattle: Seventh Revised Edition, 2001. Washington, DC: The National Academies Press. https://doi.org/10.17226/9825 Powell, J. M. and Rotz, C. A. (2015). Measures of nitrogen use efficiency and nitrogen loss from dairy production systems. Journal of Environmental Quality, 44, 336-344. https://doi.org/10.2134/jeq2014.07.0299 Recktenwald, E. B., Ross, D. A., Fessenden, S. W., Wall, C. J. and Van Amburgh, M. E. (2014). Urea-N recycling in lactating dairy cows fed diets with 2 different levels of dietary crude protein and starch with or without monensin. Journal of Dairy Science, 97, 1611-1622. https://doi.org/10.3168/jds.2013-7162 Rotz, C. A., Satter, L. D., Mertens, D. R. and Muck, R. E. (1999). Feeding strategy, nitrogen cycling, and profitability of dairy farms. Journal of Dairy Science, 82, 2841-2855. https://doi.org/10.3168/jds.S0022-0302(99)75542-6 Spiekers, H. and Obermaier, A. (2007). Milchhrnstoffgehalt und N-Aussheidung.L SuB Heft 4-5/07, 2007. S. III-4 bis III-8. Straalen, W. M. (1995). Modelling of nitrogen flow and extraction in dairy cows. PhD thesis. Landbouw Universiteit Wageningen. ISBN 90-5485-475-8.

In the dairy breeding industry, prediction of bull fertility in artificial insemination (AI) is important for efficient and economically sustainable production. However, it is challenging to identify bulls with superior fertility applying conventional in vitro sperm assays. In the present study, sperm functionality was investigated to identify a multivariate model that could predict fertility. Two groups of young Norwegian Red bulls were selected, one with inferior fertility (18 bulls) and one with superior fertility (19 bulls) based on non-return rate after 56 days (NR56). Frozen-thawed semen doses were analysed for sperm chromatin integrity, viability, acrosome integrity, motility, and ATP content. A targeted approach was used to study intracellular concentrations of amino acids and trace elements in viable sperm cells. Significant differences between the two groups of bulls were observed, both for sperm functional attributes and intracellular concentrations of metabolites. Pearson correlation analyses indicated a negative relationship between NR56 and chromatin integrity parameters, DNA fragmentation index (DFI) and high DNA stainability (HDS). Several motility parameters correlated positively with NR56. The concentrations of cysteine and glutamic acid in sperm cells correlated negatively with NR56, while the concentrations of aspartic acid, leucine and serine showed a positive NR56-correlation. The sperm intracellular concentrations of the trace elements Fe, Al and Zn, correlated negatively with NR56. Correlations were observed between several sperm parameters and metabolites. Stepwise multiple regression analysis indicated that the best predictor of NR56 was a model containing %DFI, together with the intracellular sperm concentration of aspartic acid, Fe and Zn. This model explained 59% of the variability in NR56.

Chronic subclinical mastitis (SCM) is characterized by a long-term inflammation in the udder with high somatic cell count (SCC) in milk. Previously, several novel alternative SCM traits for Norwegian Red (NR) cattle have been defined to improve breeding strategies against chronic SCM. Quantitative trait loci and candidate genes affecting chronic SCM in NR have been identified. The aim of this study was to analyze the expression profiles of 14 selected candidate genes (RAD17, ACOT2, ACOT4, FOS, CXCL1, CXCL8, CCNB1, CDK7, TGFB3, SEL1L, STAT4, C6, GLI2, and SLC18A2). Twenty healthy NR cows with official genomic estimated breeding values (GEBV) for lactation average somatic cell scores (LSCS) were selected. Ten cows had high GEBV for LSCS (cows with low probability to have high SCC in milk during lactation) and 10 cows had low GEBV for LSCS (cows with high probability of having high SCC in milk). We isolated RNA from unstimulated peripheral blood mononuclear cells from these. Two out of the 14 analyzed genes showed significantly different results between groups. The group with high GEBV for LSCS displayed significantly higher expression of the CXCL1 gene than the low GEBV group. Grouping by lactation stage revealed significant differential expression of the FOS gene, with higher expression in early lactation (2-3 mo after calving) compared with late lactation (7-8 mo after calving). In addition, flow cytometry was performed on the peripheral blood mononuclear cells samples to analyze if number and type of isolated cells influenced the gene expression in the groups. The results in the current study provide identified genes that can be considered as possible candidate genes for chronic SCM in NR cows.

The current study aimed to investigate new udder health traits based on data from automatic milking systems (AMS) for use in routine genetic evaluations. Data were from 77 commercial herds; out of these, 24 had equipment for measuring online cell count (OCC), whereas all had data on electrical conductivity (EC). A total of 4,714 Norwegian Red dairy cows and 2,363,928 milkings were included in the genetic analyses. Electrical conductivity was available on quarter level for each milking, whereas OCC was measured per milking. The AMS traits analyzed were log-transformed online cell count (lnOCC), maximum conductivity (ECmax), mean conductivity (ECmean), elevated mastitis risk (EMR), and log-transformed EMR (lnEMR). In addition, lactation mean somatic cell score (LSCS) was collected from the Norwegian dairy herd recording system. Elevated mastitis risk expresses the probability of a cow having mastitis and was calculated from smoothed lnOCC values according to individual trend and level of the OCC curve. The udder health traits from AMS were analyzed as repeated milkings from 30 to 320 DIM, and LSCS as repeated parities. In addition, both ECmax and lnOCC were analyzed as multiple traits by splitting the lactation into 5 periods. (Co)variance components were estimated from bivariate mixed linear animal models, and investigated traits showed genetic variation. Estimated heritabilities of ECmean, ECmax, and lnEMR were 0.35, 0.23, and 0.12, respectively, whereas EMR and lnOCC both showed heritabilities of 0.09. Heritability varied between periods of lactation, from 0.04 to 0.13 for lnOCC and from 0.12 to 0.27 for ECmax, although standard errors of certain periods were large. Genetic correlations among the AMS traits ranged from 0 to 0.99. The genetic correlations between EC-based traits and OCC-based traits in AMS were 0. Genetic correlations with LSCS were favorable, ranging from 0.37 to 0.80 (±0.11–0.22). The strongest correlation (0.80 ± 0.13) was found between LSCS and lnEMR. Results question the value of ECmax and ECmean as indicators of udder health in genetic evaluations and suggest OCC to be more valuable in this manner. This study demonstrates a potential of using AMS data as additional information on udder health for genetic evaluations, although further investigation is recommended before these traits can be implemented.

Thirty-one strains of propionic acid bacteria were screened for their effects on methane production and volatile fatty acid concentrations using in vitro assays of rumen fluid from Norwegian dairy cows and a grass silage–concentrate mixture as substrate. Nine of 31 strains were further analysed for effects on substrate degradation. Propionic acid bacteria led to reductions of up to 20% in methane production. Seven strains stimulated volatile fatty acid production, and in their presence in vitro substrate degradation tended to increase (P

He significance of blood count of related breeds of the Ayrshire group of dairy cattle investigated. Information processed on the pedigrees of 181 bulls whose sperm found in 10 breeding enterprises of the RF. The average blood pressure of bulls in the Finnish Ayrshire breed was 54.2%, Swedish red - 9.9%, Norwegian red - 8.8%, Canadian - 25.7% and others - 1.4%. Bulls distributed according to the presence in their pedigrees of blood residues of related breeds of the Ayrshire group in the age aspect depending on the place of their birth and breeding enterprises, and the level of breeding value by milk of their daughters and pedigree. Most of the bulls were born in Russia and Finland (45.9 and 46.4% respectively) in their pedigrees the Finnish Ayrshire breed predominates. The ranking of bulls by official breeding value (BV) and by pedigree (BV PED ) revealed that in the best bulls according to these indicators (+100 kg and more) bloodline prevails in pedigrees by Finnish Ayrshire breed compared to the worst group (less than -100 kg). This regularity noted in pedigrees in 57.2 and 77.6% of bulls, depending on the assessment options. The BV of bulls and predicted positively and reliably correlates with the presence of Finnish blood in the pedigree (+ 0.233 * and + 0.308 **) and significantly negatively with Canadian (-0.252 * and -0.467 **). The findings are consistent with previous 2013 studies on the best rated Viking Genetics bulls.

Several factors influence the composition of milk. Among these, genetic variation within and between cattle breeds influences milk protein composition, protein heterogeneity, and their posttranslational modifications. Such variations may further influence technological properties, which are of importance for the utilization of milk into dairy products. Furthermore, these potential variations may also facilitate the production of differentiated products (e.g., related to specific breeds or specific genetic variants). The objective of this study was to investigate the genetic variation and relative protein composition of the major proteins in milk from 6 native Norwegian dairy breeds representing heterogeneity in geographical origin, using the modern Norwegian breed, Norwegian Red, as reference. In total, milk samples from 144 individual cows were collected and subjected to liquid chromatography-electrospray ionization/mass spectrometry–based proteomics for identification of genetic and posttranslational modification isoforms of the 4 caseins (αS1-CN, αS2-CN, β-CN, κ-CN) and the 2 most abundant whey proteins (α-lactalbumin and β-lactoglobulin). Relative quantification of these proteins and their major isoforms, including phosphorylations of αS1-CN and glycosylation of κ-CN, were determined based on UV absorbance. The presence and frequency of genetic variants of the breeds were found to be very diverse and it was possible to identify rare variants of the CN, which, to our knowledge, have not been identified in these breeds before. Thus, αS1-CN variant D was identified in low frequency in 3 of the 6 native Norwegian breeds. In general, αS1-CN was found to be quite diverse between the native breeds, and the even less frequent A and C variants were furthermore detected in 1 and 5 of the native breeds, respectively. The αS1-CN variant C was also identified in samples from the Norwegian Red cattle. The variant E of κ-CN was identified in 2 of the native Norwegian breeds. Another interesting finding was the identification of αS2-CN variant D, which was found in relatively high frequencies in the native breeds. Diversity in more common protein genetic variants were furthermore observed in the protein profiles of the native breeds compared with milk from the high-yielding Norwegian Reds, probably reflecting the more diverse genetic background between the native breeds.

International audience; The objective of this study was to investigate the effect of cow genotype and parity on dry matter intake (DMI) and production efficiencies in pasture-based systems. Three dairy cow genotypes were evaluated over 3 yr; 40 Holstein-Friesian (HF), 40 Jersey × HF (JEX), and 40 Norwegian Red × JEX (3WAY) each year, with each genotype grazed in equal numbers on 1 of 4 grazing treatments in a 2 × 2 factorial arrangement of treatments [diploid or tetraploid perennial ryegrass (Lolium perenne L.) with or without white clover (Trifolium repens L.)]. A total of 208 individual cows were used during the experiment. The effect of parity (lactation 1, 2, and 3+) was also evaluated. Individual DMI was estimated 8 times during the study, 3 times in 2015 and in 2017, and twice in 2016, using the n-alkane technique. Days in milk at each DMI measurement period were 64, 110, and 189, corresponding to spring, summer, and autumn. Measures of milk production efficiency calculated were total DMI/100 kg of body weight (BW), milk solids (kg fat + protein; MSo)/100 kg of BW, solids-corrected milk (SCM)/100 kg of BW, and unité fourragère lait (net energy requirements for lactation equivalent of 1 kg of standard air-dry barley; UFL) available for standard (4.0% fat and 3.1% protein content) milk production after accounting for maintenance. During the DMI measurement periods HF had a greater milk yield (23.2 kg/cow per d) compared with JEX and 3WAY (22.0 and 21.9 kg/cow per d, respectively) but there was no difference in MSo yield. Holstein-Friesian and JEX, and JEX and 3WAY had similar DMI, but HF had greater total DMI than 3WAY (DMI was 17.2, 17.0, and 16.7 kg/cow per d for HF, JEX, and 3WAY, respectively). Jersey × Holstein-Friesian cows were the most efficient for total DMI/100 kg of BW, SCM/100 kg of BW, and MSo/100 kg of BW (3.63, 4.96, and 0.39 kg/kg of BW) compared with HF (3.36, 4.51, and 0.35 kg/kg of BW) and 3WAY (3.45, 4.63, and 0.37 kg/kg of BW), respectively. Unité fourragère lait available for standard milk production after accounting for maintenance was not different among genotypes. As expected, DMI differed significantly among parities with greater parity cows having higher DMI and subsequently higher milk and MSo yield. Although all 3 genotypes achieved high levels of DMI and production efficiency, JEX achieved the highest production efficiency. Some of the efficiency gains (SCM/100 kg of BW, MSo/100 kg of BW, and total DMI/100 kg of BW) achieved with JEX decreased when the third breed (Norwegian Red) was introduced.

Milking-time testing (MTT) is a method for evaluating the vacuum conditions in the teatcup during milking. The purpose is to evaluate the possible impact of the milking and milking equipment on udder health and milk quality. The method is commonly implemented by herd health advisory services, but results are interpreted empirically due to lack of scientific documentation on relationships between MTT result variables and objective measures of udder health. The current study was conducted to increase our understanding of associations between cow-level differences in composite milk somatic cell count (CMSCC) and MTT results in dairy cows milked in 3 different milking systems; automatic milking systems (AMS), milking parlors, and pipeline milking systems. Data from 7069 cows (predominantly Norwegian Red breed) in 1009 herds were used in a cross-sectional study. Multilevel linear regression models with a random intercept at herd level were used to describe relationships between CMSCC (on logarithmic scale) and the following MTT explanatory variables: average vacuum level in the short milk tube and mouthpiece chamber in the main milking and overmilking periods, the duration of these two periods, and vacuum stability, measured by sudden vacuum drops in the short milk tube. The models were corrected for the herd effect, mastitis history and differences in milk yield, lactation stage and parity between cows. Separate models were run for AMS, milking parlors, and pipeline milking systems, because this approach allowed for comparison between systems and for evaluation of the herd effect independently of milking system. The models described 8-10 % of the variation in CMSCC, indicating that MTT could only explain a relatively small proportion of a large total variation in CMSCC. In most observations, vacuum levels in the short milk tube during main milking were within the range recommended by the International Organization for Standardization. The results from our multivariable models showed decreasing CMSCC with increasing vacuum level in the short milk tube during the main milking period in AMS and milking parlors. Similarly, decreasing CMSCC was also associated with increasing duration of the main milking period in all 3 systems. These relationships are important for the interpretation of MTT results under practical conditions; finding high vacuum levels and long milking durations in a MTT is not associated with elevated CMSCC. In AMS herds, we also found indications that the relationships were different for cows where a case of mastitis had been treated before the MTT.

The Finnish population of the modern Ayrshire breed is known to have been formed as a result of a complex reproductive crossing of the Ayrshire breed with a number of northern breeds. The Russian Ayrshire population is a reflection of global trends in working with livestock in different countries, namely Scandinavia, Finland and Canada. The purpose of the research is to assess the ratio of the breed component in the Ayrshire herd of Public Company "BP of V.I. Chapaeva" for the last 10 years and the dynamics between the closest generations (the dairy herd and the replacement population). With the help of electronic databases of bulls and mothers of Ayrshire breed bulls of the Selection Breeding Center (RRIFAGB) 13820 pedigree records were studied, including 2324 heifers, 2741 cows of dairy herd, 8755 archival records of the breeding stock. It has been established that fathers of mothers and fathers of mothers of mothers in the herd pedigree are most often represented by bulls with simple blood characteristics: usually Finnish, less often Finnish-Swedish, even less often Canadian selection. The sum of the component pedigree, approved by the FABA, a herd of PC "BP of V.I. Chapaeva" on average since 2013 meets the requirements of section A (Main book). During this period, the share of Finnish Ayrshire is growing and the share of Canadian Ayrshire is decreasing, with constant weight of red Swedish and Norwegian red breed components. Other components of the breed are partially found. Consequently, in the south of Russia, a herd of Ayrshire breed with Finnish-Canadian genetics is used, selection is conducted against the background of climatic and feeding conditions that are not typical for breeding history.

International audience; Accurate estimates of feed intake are important in order to develop accurate ration formulations, for selecting livestock according to production efficiency, and for reducing environmental impact of livestock. The present study assessed the accuracy of n-alkanes to estimate individual herbage intake and diet botanical composition of cattle fed natural forages, typical to Madagascar. The effect of two different forage allowances and seasons on the herbage intake was also tested. Eight Norwegian red pie sires (232 ± 20 kg BW) were orally dosed twice daily with paper pellets containing 456.61 ± 21.64 mg of C32 alkane as external marker. Animals were housed in individual pens and fed with mixtures of five forages species typically used by farmers in the rainy season (Aristida multicaulis, Hyparrhenia rufa, Imperata cylindrical, Urochloa brizantha and Stylosanthes guyanensis) and the dry season (Chrysopogon serrulatus, Cynodon dactylon, Imperata cylindrica, Lolium multiflorum and Leersia hexandra Sw). The sires were randomly assigned to two different forage allowances: (i) ad libitum with a refusal of 5 % and (ii) 1.1 % DM of body weight (BW). The n-alkane pairs C31:C32 and C32:C33 and the ratio C32/Acid Insoluble Ash (AIA) in plants and faeces were used to estimate the herbage intake. The botanical composition of the diet was estimated using the n-alkane profile from C27 to C35 in individual plant species and faeces, by least squares optimization. The n-alkane pairs underestimated (P < 0.0001) the herbage intake by 25 % in the dry season, for both forage allowances and 26 % for animals receiving ad libitum diet, regardless of the season. In contrast, the intake estimates based on both n-alkane pairs did not differ from the measured intake for animals receiving low forage allowance during the rainy season. The C32/AIA underestimated the actual herbage intake, by 50 %, for animal consuming ad libitum diet, for both seasons (P < 0.0001). The n-alkane faecal recovery (AFR) corrections factors set affected (P < 0.01) the estimated proportions of each plant species, that comprised the diet in both seasons. The application of appropriate AFR permitted to have a better accuracy of diet botanical composition estimates. It is concluded that plant wax n-alkanes are advantageous for estimating both diet botanical composition and herbage intake in cattle. However, for improving the prediction, it is important to measure the actual AFR before the calculation.

The research on the genetics of bull fertility is limited, many studies are old, estimates are often based on few observations or few bulls, and with large or lacking standard errors. With more than 20 years of data on semen characteristics available from Norwegian Red (NR) bulls at the performance test station and the AI center, an opportunity existed to increase our knowledge of these traits both in a local and global perspective. With cow fertility improving in many cattle populations, further progress in cattle fertility might be achieved on the bull side. Furthermore, new technologies such as sexed semen is becoming increasingly popular, and bulls that produce a larger amount of semen with the higher quality required for such methods might be more desired by breeding companies in the future. In the NR population, bull fertility is assessed first in a bull breeding soundness evaluation at the test station and later during quality assessment of semen at the artificial insemination (AI) center. During performance testing, the bulls body weight at 150 and 330 days and average growth were also recorded. Using these data, the main aims of this project were: 1) To estimate genetic parameters and genetic trends for semen characteristics from NR bulls at the performance test station, 2) To estimate genetic correlations between semen characteristics and body weights and growth measured on NR bulls at the test station, and 3) To estimate genetic parameters for semen characteristics of bulls at the AI center, and to estimate genetic correlations between these traits and corresponding semen characteristics measured at the performance test station. The semen characteristics data from the test station consisted of 14,972 ejaculates from 3,927 young Norwegian Red bulls. The traits recorded were semen volume, sperm concentration, motility in fresh samples, and after storing the semen in a refrigerator for 24 and 48 hours, and sperm defects. Body weight and growth traits were available for 2,034 of these bulls. From the AI center, data from 137,919 ejaculates from 3,145 bulls were analysed including records on semen weight, sperm concentration, motility before and after cryopreservation, motility change during cryopreservation, and number of accepted straws made from the semen collection. Results show that all the semen characteristic traits are heritable with moderate heritability for amount of semen (volume or weight), sperm concentration and number of straws produced from each collection (0.14 to 0.22), and low heritability for motility traits (0.02 to 0.08) and sperm defects (0.02). Heritabilities for traits measured on bulls at the AI center were generally higher than the corresponding traits measured on more immature and unexperienced bulls at the test station. Most semen characteristic traits were favorably genetically correlated, or had a genetic correlation close to zero, except for a negative genetic correlation between semen weight and sperm concentration for bulls at the AI center. All test station traits showed a slightly unfavorable genetic trend between 1994 and 2016 implying that the andrology testing and the minimum semen quality requirements before selection of AI bulls have not been sufficient to genetically improve semen characteristics over time. Body weight was favorably genetically correlated with all semen characteristic traits, while average daily weight gain was unfavorably genetically correlated with sperm concentration (-0.25 ± 0,15) and motility in fresh samples (-0.53 ± 0.34). Genetic correlations between corresponding traits at the test station and AI center were high for semen volume/weight (0.83) and concentration (0.78), and somewhat lower for motility in fresh samples (0.49). To reverse the unfavorable genetic trends and breed for bulls with better sperm quality we suggest including semen characteristics traits in the routine genetic evaluation of NR. Genomic breeding values for these traits can be used for selection of bull calves and will also provide a means for monitoring bull fertility in the population. Estimating genetic correlations between semen characteristics and other traits in the total merit index of Norwegian Red should be prioritized. Such correlations are largely lacking in the literature and might explain the negative trends observed. Genetiske studier av oksefruktbarhet er i fåtall og de studiene som finnes er ofte gamle, estimatene er basert på få observasjoner eller få dyr, eller standardfeilen på estimatene er store eller mangler. Med mer enn 20 år med sædkvalitetsdata, innhentet fra test- og seminstasjon til Norsk Rødt Fe (NRF), så vi en mulighet for å øke kunnskapsgrunnlaget for disse egenskapene både i et lokalt og globalt perspektiv. Nå som kufruktbarheten bedres i storfepopulasjoner verden rundt, kan en økning i oksefruktbarhet ha større betydning. Videre øker interessen for nye teknologier og metoder slik som kjønnsseparert sæd. Dette kan gi ytterligere behov for okser som produserer en god mengde sæd med god kvalitet i fremtiden. I NRF populasjonen undersøkes sædkvalitet først ved en andrologitest på teststasjonen og senere ved kvalitetssjekk av sæden på seminstasjonen. I tillegg til andrologitesten, veies oksene på teststasjonen ved 150 og 330 dager og den gjennomsnittlige tilveksten registreres. Ved hjelp av disse dataene ønsket vi og: 1) Estimere genetiske parametere og genetiske trender for sædkvalitetsegenskaper målt på okser på teststasjonen, 2) Estimere genetiske korrelasjoner mellom sædkvalitetsegenskaper og vekt og tilvekst målt på okser på teststasjonen og 3) Estimere genetiske parametere for sædkvalitetsegenskaper målt på okser på seminstasjonen, samt estimere genetiske korrelasjoner mellom disse egenskapene og korresponderende egenskaper fra teststasjonen. Sædkvalitetsdata fra teststasjonen bestod av 14,972 ejakulater fra 3,927 okser. Egenskapene som ble målt var sædvolum, sædkonsentrasjon, motilitet i fersk prøve, samt motilitet etter lagring i kjøleskap i henholdsvis 24 og 48 timer, og spermiedefekter. Registreringer av kroppsvekt og gjennomsnittlig tilvekst var tilgjengelig for 2,034 av disse oksene. Fra seminstasjonen hadde vi data fra 137,919 ejakulater fra 3,145 okser. Disse inkluderte registreringer av sædvekt, sædkonsentrasjon, motilitet før og etter kryopreservering, endring i motilitet under kryopreservering og antall aksepterte sædstrå fra uttaket. Resultatene viser at sædkvalitetsegenskapene er arvelige med moderate arvegrader for mengde (volum og vekt), konsentrasjon og antall aksepterte strå (0.14 til 0.22), og lav for motilitet (0.02 til 0.08) og spermiedefekter (0.02). Arvegradene for egenskapene målt på seminstasjonen var generelt høyere enn for korresponderende egenskaper målt på de mer umodne og uerfarne oksene på teststasjonen. De fleste sædkvalitetsegenskapene var fordelaktig genetisk korrelert eller hadde en genetisk korrelasjon nær null. Unntaket var en negativ genetisk korrelasjon mellom sædvekt og konsentrasjon for okser på seminstasjonen. Alle sædkvalitetsegenskapene målt på teststasjonen har hatt en uønsket genetisk trend mellom 1994 og 2016. Dette indikerer at andrologitesten og minimumskravene til sædkvalitet før seleksjon av seminokser ikke har vært tilstrekkelig for å øke oksefruktbarheten over tid. Kroppsvekt var positivt korrelert med sædkvalitet, mens gjennomsnittlig tilvekst hadde en uønsket, genetisk korrelasjon til sædkonsentrasjon (-0.25 ± 0,15) og motilitet i fersk prøve (- 0.53 ± 0.34). Genetiske korrelasjoner mellom korresponderende egenskaper på test- og seminstasjonen var høy for volum/vekt (0.83) og konsentrasjon (0.78) og noe lavere for motilitet i fersk prøve (0.49). Vi foreslår å inkludere sædkvalitetsegenskaper i den rutinemessige genetiske evalueringen av NRF for å kunne reversere de uønskede genetiske trendene og avle for okser med bedre sædkvalitet. Genomiske avlsverdier for disse egenskapene kan brukes for å selektere oksekalver, i tillegg til å kunne brukes for å overvåke oksefruktbarheten i populasjonen fremover. Det bør prioriteres å estimere genetiske korrelasjoner mellom sædkvalitet og andre egenskaper i det overordnede avlsmålet til NRF. Slike korrelasjoner mangler i litteraturen og kan være noe av forklaringen for de negative genetiske trendene som her ble observert for sædkvalitetsegenskaper. Norsk forskningsråd

Compared with cow fertility, genetic analyses of bull fertility are limited and based on relatively few animals. The aim of the present study was to estimate genetic parameters for semen characteristics of Norwegian Red bulls at the artificial insemination (AI) center (Geno AI station, Stange, Norway) and to estimate genetic correlations between some of these traits and andrology traits measured at the performance test station. The data from the AI center consisted of records from 137,919 semen collections from 3,145 bulls with information on semen weight, sperm concentration, motility before and after cryopreservation, motility change during cryopreservation, and number of accepted straws made. Data from the performance test station included 12,522 observations from 3,219 bulls on semen volume, concentration, and motility (%) when fresh and after storing for 24 and 48 h. Genetic parameters were estimated using linear animal repeatability models that included fixed effects of year-month of observation, age of bull, interaction between semen collection number, and interval between collections for all traits and type of diluter for postcryopreservation traits. The random effects included test-day, permanent environmental, and additive genetic effects of the bull. Based on records from the AI center, we found that semen weight, sperm concentration, and number of straws were moderately heritable (0.18-0.20), whereas motility had a lower heritability (0.02-0.08). Heritability of motility (%) was higher after cryopreservation than before. Genetic correlations among the semen characteristics ranged from unfavorable (-0.35) to favorable (0.93), with standard errors ranging from 0.02 to 0.22. Among the most precise genetic correlation estimates, number of straws made from a batch correlated favorably with semen weight (0.62 ± 0.06) and sperm concentration (0.44 ± 0.08), whereas sperm concentration was negatively correlated with weight (-0.33 ± 0.09). The genetic correlation between motility (%) before and after cryopreservation was 0.64 ± 0.14, and motility change during cryopreservation had a strong favorable genetic correlation with motility after cryopreservation (-0.93 ± 0.02). The estimated genetic correlation (standard error) between the traits volume, concentration, and motility when fresh measured at the performance test station and their respective corresponding traits at the AI center were 0.83 (0.05), 0.78 (0.09), and 0.49 (0.31). The final product at the AI center (number of accepted straws) correlated genetically favorably with all semen characteristic traits recorded at the performance test station (ranging from 0.51 to 0.67). Our results show that the andrology testing done at the performance test station is a resource to identify the genetically best bulls for AI production.

Including feed efficiency into breeding goals could be a key in ensuring sustainable dairy cattle production as selection could be based on how efficient a cow is in terms of what it consumes and produces all through the lactation period. Hence, prioritizing feed efficiency could aid profitability and reduced methane emission in dairy cow sector. The objective of this study was to explore random regression models of varying order of Legendre polynomials to fit feed intake and feed efficiency records in Norwegian Red dairy cows. Data included 2632 daily dry matter intake and average daily milk yield records from 45 cows in 1 to 5 parities for 56 days of lactation. A random regression model with both random and fixed regressions fitted by Legendre polynomials of order 1 to 5 for fixed effects curve and 1 to 2 for random animal effect curve were compared while accounting for homogeneous and four heterogeneous classes of residual variance across the lactation. Models were evaluated by goodness of fit (LogL and -½ AIC values), graphical inspection of variance functions for the random animal effect, while difference between the standard error and regression solution for the fixed effect curves. The results showed improvement in goodness of fit moving from order 1 to order 2 but order 3 showed no convergence for the animal random effect in both feed intake and feed efficiency models. For feed intake analyses, order 1,2,4 and 5 was significant while for feed efficiency analysis only order 3 was significant for fixed effect curves. In general, the result showed that random regression models using fifth order Legendre polynomials (Mleg5) for fixed effect curve and first order Legendre polynomials (Aleg1) with heterogeneous residual variance was sufficient to fit feed intake records. While random regression models using third order Legendre polynomials (Mleg3) for fixed effect curve and second order Legendre polynomials (Aleg2) with homogeneous residual variance was sufficient to fit feed efficiency data. In conclusion, random regression model with Legendre polynomial of order 3 for fixed effect curve and order 2 with homogeneous classes of residual variances is a good model for fitting feed efficiency records, Legendre polynomial of order 5 for fixed effect curve and order 1 with heterogeneous residual variances could be an appropriate model to consider while fitting feed intake records to avoid complexity of the models. EM-ABG

In this study, the complexity of chromatin integrity was investigated in frozen-thawed semen samples from 37 sires with contrasting fertility, expressed as 56-day non-return rates (NR56). Protamine deficiency, thiols, and disulfide bonds were assessed and compared with previously published data for DNA fragmentation index (DFI) and high DNA stainability (HDS). In addition, in vitro embryo development and sperm DNA methylation were assessed using semen samples from 16 of these bulls. The percentages of DFI and HDS were negatively associated with NR56 and cleavage rate and positively associated with sperm protamine deficiency (p

The objective of the study was to evaluate the potential of Fourier transform infrared spectroscopy (FTIR) analysis of milk samples to predict body energy status and related traits (energy balance (EB), dry matter intake (DMI) and efficient energy intake (EEI)) in lactating dairy cows. The data included 2371 milk samples from 63 Norwegian Red dairy cows collected during the first 105 days in milk (DIM). To predict the body energy status traits, calibration models were developed using Partial Least Squares Regression (PLSR). Calibration models were established using split-sample (leave-one cow-out) cross-validation approach and validated using an external test set. The PLSR method was implemented using just the FTIR spectra or using the FTIR together with milk yield (MY) or concentrate intake (CONCTR) as predictors of traits. Analyses were conducted for the entire first 105 DIM and separately for the two lactation periods: 5 ≤ DIM ≤ 55 and 55 < DIM ≤ 105. To test the models, an external validation using an independent test set was performed. Predictions depending on the parity (1st, 2nd and 3rd-to 6th parities) in early lactation were also investigated. Accuracy of prediction (r) for both cross-validation and external test set was defined as the correlation between the predicted and observed values for body energy status traits. Analyzing FTIR in combination with MY by PLSR, resulted in relatively high r-values to estimate EB (r = 0.63), DMI (r = 0.83), EEI (r = 0.84) using an external validation. Only moderate correlations between FTIR spectra and traits like EB, EEI and dry matter intake (DMI) have so far been published. Our hypothesis was that improvements in the FTIR predictions of EB, EEI and DMI can be obtained by (1) stratification into different stages of lactations and different parities, or (2) by adding additional information on milking and feeding traits. Stratification of the lactation stages improved predictions compared with the analyses including all data 5 ≤ DIM ≤105. The accuracy was improved if additional data (MY or CONCTR) were included in the prediction model. Furthermore, stratification into parity groups, improved the predictions of body energy status. Our results show that FTIR spectral data combined with MY or CONCTR can be used to obtain improved estimation of body energy status compared to only using the FTIR spectra in Norwegian Red dairy cattle. The best prediction results were achieved using FTIR spectra together with MY for early lactation. The results obtained in the study suggest that the modeling approach used in this paper can be considered as a viable method for predicting an individual cow's energy status.

Genomic selection in modern farming demands sufficient semen production in young bulls. Factors affecting semen quality and production capacity in young bulls are not well understood; DNA methylation, a complicated phenomenon in sperm cells, is one such factors. In this study, fresh and frozen-thawed semen samples from the same Norwegian Red (NR) bulls at both 14 and 17 months of age were examined for sperm chromatin integrity parameters, ATP content, viability, and motility. Furthermore, reduced representation bisulfite libraries constructed according to two protocols, the Ovation® RRBS Methyl-Seq System (Ovation method) and a previously optimized gel-free method and were sequenced to study the sperm DNA methylome in frozen-thawed semen samples. Sperm quality analyses indicated that sperm concentration, total motility and progressivity in fresh semen from 17 months old NR bulls were significantly higher compared to individuals at 14 months of age. The percentage of DNA fragmented sperm cells significantly decreased in both fresh and frozen-thawed semen samples in bulls with increasing age. Libraries from the Ovation method exhibited a greater percentage of read loss and shorter read size following trimming. Downstream analyses for reads obtained from the gel-free method revealed similar global sperm DNA methylation but differentially methylated regions (DMRs) between 14- and 17 months old NR bulls. The majority of identified DMRs were hypomethylated in 14 months old bulls. Most of the identified DMRs (69%) exhibited a less than 10% methylation difference while only 1.5% of DMRs exceeded a 25% methylation difference. Pathway analysis showed that genes annotated with DMRs having low methylation differences (less than 10%) and DMRs having between 10 and 25% methylation differences, could be associated with important hormonal signaling and sperm function relevant pathways, respectively. The current research shows that RRBS in parallel with routine sperm quality analyses could be informative in reproductive capacity of young NR bulls. Although global sperm DNA methylation levels in 14 and 17 months old NR bulls were similar, regions with low and varying levels of DNA methylation differences can be identified and linked with important sperm function and hormonal pathways. Copyright © 2020 Khezri, Narud, Stenseth, Zeremichael, Myromslien, Wilson, Ahmad and Kommisrud. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

At birth, calves are functionally monogastric and remain so for the first weeks of life. Milk in the rumen may cause indigestion, diarrhea, and reduced growth. Calves are often fed cold milk from a large-aperture teat, but warm milk and sucking behavior are believed to trigger the esophageal reflex. The aim of this study was to use radiography to estimate the lowest milk temperature that can be given to dairy calves at high and low intake rates without causing milk in the rumen. Our hypothesis was that cold milk drunk at high speed would cause insufficient closure of the esophageal groove and hence milk in the rumen. Fifteen Norwegian Red calves, 9 to 27 d of age, weighing between 45.5 and 71.0 kg, were tested according to the response surface pathway design. Each calf was offered 4 L of milk from both a small- (2 mm) and a large-aperture (19 mm) teat. The milk contained barium sulfate, and radiography was applied before, during, and after the milk meal. Following radiography, the calves were returned to a group pen and observed for 2 h using continuous live behavioral observation to detect signs of abdominal pain or discomfort. Starting with a low number of subjects and increasing this number with increasing design levels reduces the sample size without reducing the statistical power. The minimum milk temperature was estimated to be 8°C. No behavioral signs of pain or discomfort were observed, but shivering was noted in several calves drinking 8°C milk. These results strengthen the argument that calves can be fed large milk meals without risk of causing milk in the rumen, even cold milk drunk at high speed.

The primary objective of this study was to design a growth profile from 3 mo through puberty to insemination that allows heifers to enter the milking herd at 22 mo of age without impairing milk production over 3 lactations compared with the current rearing practice leading to an age at first calving of 26 mo. Eighty heifers born into the Norwegian University of Life Sciences herd, 40 each from yr 2010 and 2011, were randomly assigned according to birth order either to a high or low intake energy treatment. Each energy group was further subdivided into 2 protein groups, 1 fed according to requirements and 1 fed 10% excess protein, to ensure that metabolizable protein supply would meet the requirements for rapidly growing bone and muscle of today's genetically improved Norwegian Red heifer. Utilizing growth rate and feed composition the energy and protein supply was regulated with roughage quality in a diet containing 1 kg/d of concentrate of 2 qualities. Average daily gain from 3 mo to confirmed pregnancy ranged from 900 to 1,000 g/d among high-energy animals, with high protein-fed animals growing the fastest. Growth rates for low energy animals were700 g/d. From confirmed pregnancy to first calving, all animals were fed only grass silage to sustain an average daily gain500 (high energy) or600 g/d (low energy), excluding fetal and gravid uterus weight, and they reached a postcalving weight of 530 (high energy) to 570 kg (low energy) with body condition score ranging from 3.42 to 3.93 at calving. We have shown that heifers fed a high-energy treatment with the required amount of protein from 3 mo of age to successful insemination combined with an average daily gain of ∼500 g/d throughout pregnancy will calve at 22 mo without becoming over-conditioned at calving and without impairing performance over 3 lactations. We recommend reducing rearing time by 4 mo, planning for an age at first calving of 22 mo of age. This rearing practice would also improve energy efficiency during the heifer rearing period.