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A genome-wide association study of resistance to retained placenta (RETP) using 632,212 Holstein cows and 74,747 SNPs identified 200 additive effects with p-values < 10−8 on thirteen chromosomes but no dominance effect was statistically significant. The regions of 87.61–88.74 Mb of Chr09 about 1.13 Mb in size had the most significant effect in LOC112448080 and other highly significant effects in CCDC170 and ESR1, and in or near RMND1 and AKAP12. Four non-ESR1 genes in this region were reported to be involved in ESR1 fusions in humans. Chr23 had the largest number of significant effects that peaked in SLC17A1, which was involved in urate metabolism and transport that could contribute to kidney disease. The PKHD1 gene contained seven significant effects and was downstream of another six significant effects. The ACOT13 gene also had a highly significant effect. Both PKHD1 and ACOT13 were associated with kidney disease. Another highly significant effect was upstream of BOLA-DQA2. The KITLG gene of Chr05 that acts in utero in germ cell and neural cell development, and hematopoiesis was upstream of a highly significant effect, contained a significant effect, and was between another two significant effects. The results of this study provided a new understanding of genetic factors underlying RETP in U.S. Holstein cows. [ABSTRACT FROM AUTHOR]

The aims of this study were to conduct a single-step genome-wide association to identify genomic regions associated with milk urea (MU) and to estimate genetic correlations between MU and milk yield (MY), milk composition (calcium content [CC], fat percentage [FP], protein percentage [PP], and casein percentage [CNP]), and cheese-making properties (CMP; coagulation time [CT], curd firmness after 30 min from rennet addition [a30], and titratable acidity [TA]). The used data have been collected from 2015 to 2020 on 78,073 first-parity (485,218 test-day records) and 48,766 second-parity (284,942 test-day records) Holstein cows distributed in 671 herds in the Walloon Region of Belgium. Data of 565,533 SNP located on 29 BTA of 6,617 animals (1,712 males) were used. Random regression test-day models were used to estimate genetic parameters through the Bayesian Gibbs sampling method. The SNP solutions were estimated using a single-step genomic BLUP approach. The proportion of the total additive genetic variance explained by windows of 50 consecutive SNPs (with an average size of ∼216 kb) was calculated, and the top-3 genomic regions explaining the largest rate of the genetic variance were considered promising regions and used to identify potential candidate genes. Mean (SD) MU was 25.38 (8.02) mg/dL and 25.03 (8.06) mg/dL in the first and second lactation, respectively. Mean heritability estimates for daily MU were 0.21 and 0.23 for the first and second lactation, respectively. The genetic correlations estimated between MU and MY, milk composition, and CMP were quite low (ranged from −0.10 [CC] to 0.10 [TA] and −0.05 [CT] to 0.13 [TA] for the first and second lactations, respectively). The top-3 regions associated with MU were located from 80.61 to 80.74 Mb on BTA6, 103.26 to 103.41 Mb on BTA11, and 1.59 to 2.15 Mb on BTA14. Genes including KCNT1 , MROH1 , SHARPIN , TSSK5 , CPSF1 , HSF1 , TONSL , DGAT1 , SCX , and MAF1 were identified as positional candidate genes for MU. The findings of this study can be used for a better understanding of the genomic architecture underlying MU in Holstein cattle. [ABSTRACT FROM AUTHOR]

This study aimed to establish a standard urine profile for pregnant cows, commonly seen patients in veterinary clinics. Urine samples from 15 pregnant cows (6 Belgian Blue and 9 Holstein) of various ages were analysed, all showing no clinical signs of urinary tract disease. Samples were collected during preventive check-ups, either by spontaneous micturition or catheterisation. Macroscopic evaluation and urine dipstick tests revealed a mean pH of 8.17 ± 0.49. Moderate glycosuria and proteinuria were detected in two animals. No urobilinogen, ketone bodies, haemoglobin, or traces of blood were found. Laboratory urinalysis provided values (with 95% confidence intervals): osmolarity 493–1110.00 mOsm/l, sodium 52.00–122.00 mmol/l, calcium 1.28–3.98 mmol/l, potassium 76–144.00 mmol/l, magnesium 5.00–8.00 mmol/l, chlorine 40.00–80.00 mmol/l, protein 35.00–104.00 mg/l, glucose 0.40–1.27 mmol/l, creatinine 34.00–76.00 mmol/l, and urea 681.00–2086 mmol/l. These findings present the initial descriptive values of urine biochemical parameters in pregnant cows, emphasising their significance in assessing animal health. This research underscores its relevance by providing fundamental insights into animal health, offering a pathway to enhance agricultural sustainability and address food security, echoing the United Nations' Sustainable Development Goals 1, 2, 8 and 12. [ABSTRACT FROM AUTHOR]

A genome-wide association study (GWAS) of fat percentage (FPC) using 1,231,898 first lactation cows and 75,198 SNPs confirmed a previous result that a Chr14 region about 9.38 Mb in size (0.14–9.52 Mb) had significant inter-chromosome additive × additive (A×A) effects with all chromosomes and revealed many new such effects. This study divides this 9.38 Mb region into two sub-regions, Chr14a at 0.14–0.88 Mb (0.74 Mb in size) with 78% and Chr14b at 2.21–9.52 Mb (7.31 Mb in size) with 22% of the 2761 significant A×A effects. These two sub-regions were separated by a 1.3 Mb gap at 0.9–2.2 Mb without significant inter-chromosome A×A effects. The PPP1R16A-FOXH1-CYHR1-TONSL (PFCT) region of Chr14a (29 Kb in size) with four SNPs had the largest number of inter-chromosome A×A effects (1141 pairs) with all chromosomes, including the most significant inter-chromosome A×A effects. The SLC4A4-GC-NPFFR2 (SGN) region of Chr06, known to have highly significant additive effects for some production, fertility and health traits, specifically interacted with the PFCT region and a Chr14a region with CPSF1, ADCK5, SLC52A2, DGAT1, SMPD5 and PARP10 (CASDSP) known to have highly significant additive effects for milk production traits. The most significant effects were between an SNP in SGN and four SNPs in PFCT. The CASDSP region mostly interacted with the SGN region. In the Chr14b region, the 2.28–2.42 Mb region (138.46 Kb in size) lacking coding genes had the largest cluster of A×A effects, interacting with seventeen chromosomes. The results from this study provide high-confidence evidence towards the understanding of the genetic mechanism of FPC in Holstein cows. [ABSTRACT FROM AUTHOR]

The aim was to investigate effects of ambient temperature-humidity index (THI) on the reproductive indices of 920 Holstein (HO) cows in the subtropics. THI was categorized as low: below 70; moderate: from 70 to 75 and high: more than 75. The high THI significantly (P < 0.001) prolonged the periods of calving interval, days open and dry period, and increased the service per conception rate. The conception rate in the high THI group (17.31%) was significantly (P < 0.001) lower than that noticed in both low (36.96%) and moderate THI (31.61%) groups. Meanwhile, high THI significantly increased the embryonic loss (P < 0.001) and abortion (P=0.043) rates compared with low (14.62% and 8.89%; respectively) and moderate (22.84%; and 11.17%; respectively) THI groups. The high THI group had a significantly (P=0.001) greater embryonic losses than the other groups. Conclusively, THI over 75 deteriorates the reproductive indices of Holstein cows. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate whether characteristics of the first lactation (FL) curve of Iranian Holstein cows are associated with survival. Cows with least 10 test-days of milk production in their FL were used. The persistency of lactation (PL) and survival were estimated using a random regression model by restricted maximum likelihood with the ECHIDDNA software. We also used the Wood model to parameterize each individual lactation curve and then analyzed various curve characteristics using an animal model. The predicted breeding value (EBV) of the characteristics of the lactation curve of the cows from day 40 to 305 was predicted. The EBV of the production range (PR) and the slope of line in increasing phase (m40,Peak) of production curve of sires with higher survival EBV were lower than other sires (P < 0.05). The estimates of PL were independent of survival estimate. Therefore, the PR from 40th day after calving can be considered as a definition of PL because the lower the PR, the flatter is the milk production curve. Genetic evaluation of young bulls for survival needs the data of death or culling of their daughters. Therefore, the bulls can genetically be evaluated for survival according to the PL and m40,Peak of FL information of their daughters. [ABSTRACT FROM AUTHOR]

This study aimed to perform genome-wide association study to identify genomic regions associated with milk production and cheese-making properties (CMP) in Walloon Holstein cows. The studied traits were milk yield, fat percentage, protein percentage, casein percentage (CNP), calcium content, somatic cell score (SCS), coagulation time, curd firmness after 30 min from rennet addition, and titratable acidity. The used data have been collected from 2014 to 2020 on 78,073 first-parity (485,218 test-day records), 48,766 second-parity (284,942 test-day records), and 21,948 third-parity (105,112 test-day records) Holstein cows distributed in 671 herds in the Walloon Region of Belgium. Data of 565,533 single nucleotide polymorphisms (SNP), located on 29 Bos taurus autosomes (BTA) of 6,617 animals (1,712 males), were used. Random regression test-day models were used to estimate genetic parameters through the Bayesian Gibbs sampling method. The SNP solutions were estimated using a single-step genomic BLUP approach. The proportion of the total additive genetic variance explained by windows of 50 consecutive SNPs (with an average size of ∼216 KB) was calculated, and regions accounting for at least 1.0% of the total additive genetic variance were used to search for positional candidate genes. Heritability estimates for the studied traits ranged from 0.10 (SCS) to 0.53 (CNP), 0.10 (SCS) to 0.50 (CNP), and 0.12 (SCS) to 0.49 (CNP) in the first, second, and third parity, respectively. Genome-wide association analyses identified 6 genomic regions (BTA1, BTA14 [4 regions], and BTA20) associated with the considered traits. Genes including the SLC37A1 (BTA1), SHARPIN , MROH1 , DGAT1 , FAM83H , TIGD5 , MROH6 , NAPRT , ADGRB1 , GML , LYPD2 , JRK (BTA14), and TRIO (BTA20) were identified as positional candidate genes for the studied CMP. The findings of this study help to unravel the genomic background of a cow's ability for cheese production and can be used for the future implementation and use of genomic evaluation to improve the cheese-making traits in Walloon Holstein cows. [ABSTRACT FROM AUTHOR]

The objective of this study was to estimate genetic parameters of health treatment cost of Holstein cows from producer-recorded health treatments in 8 herds over an 8-yr period of time. Genetic parameters of health treatment cost were estimated in first (n = 2,214), second (n = 1,487) and third (n = 800) parities of US Holstein cows. The health treatments were uniformly defined and consistently recorded by 8 high-performance dairy herds in Minnesota from 2008 to 2015. A fixed treatment cost was assigned to 14 types of health treatments, and the cost included the mean veterinary expense obtained from the veterinary clinics that serviced the 8 herds, pharmaceuticals, and labor cost. The labor cost was $18/h, and the time incurred for each type of health treatment was determined from interviews with the herd owners. The 14 types of health treatment costs were partitioned into 5 categories: mastitis (including mastitis diagnostic test), reproduction (cystic ovary, retained placenta, and metritis), lameness (hoof treatments), metabolic (milk fever, displaced abomasum, ketosis, and digestive), and miscellaneous (respiratory, injury, and other). Health treatment cost for each cow was summed by category within lactation and also across categories within lactation. The estimates of heritability for health treatment cost were 0.13, 0.04, 0.10, 0.12, and 0.04 for the mastitis, reproduction, lameness, metabolic, and miscellaneous categories, respectively, in first parity. Genetic correlations between categories of health treatment cost in first parity were greatest for mastitis and reproduction (r = 0.85); however, phenotypic correlations between all categories were small (r < 0.16). Total health treatment cost had a large genetic correlation with somatic cell score (0.93) and 305-d milk production (0.44) in first parity; however, the genetic correlation (-0.60) between total health treatment cost and udder depth in first parity indicated a genetic relationship exists between shallow udders and less total health treatment cost. Total health treatment cost across categories had a heritability estimate of 0.25 in first parity, 0.16 in second parity, and 0.17 in third parity. Consequently, genetic selection for reduced health treatment cost should be possible by using producer-recorded health treatment records supplemented with treatment costs. [ABSTRACT FROM AUTHOR]

Simple Summary: This study assessed the supplementation of two limiting milk production amino acids for dairy cows (methionine and lysine) on the lactational performance of fall-calving grazing dairy cows from Chile. Four groups were compared and 26 cows per group were randomly assigned to the following groups: (i) a control group without supplementation; (ii) a lysine group; (iii) a methionine group; and (iv) a lysine plus methionine group. Supplementation was conducted from 2 to 70 days postpartum. The group supplemented with both amino acids produced more milk protein and fat than the control group. In conclusion, the supplementation of methionine and lysine improved milk protein and fat yield in grazing dairy cows with fall parturitions; therefore, they can be used as a strategy to improve the performance of lactation in cows. The aim of this study was to evaluate the effect of the supplementation of rumen-protected (RP) methionine and lysine on milk yield, solids, and body weight over time on fall-calving grazing multiparous Holstein cows from Chile. Four treatment groups were studied and compared for the outcomes over time. The treatments were as follows: (i) CON: control (n = 26); (ii) RP lysine group (LYS; 20 g per cow per day; n = 26); (iii) RP methionine group (MET; 20 g per cow per day; n = 26); and (iv) LYS × MET (RP lysine and RP methionine 20 g of each amino acid per cow per day; n = 26). Data were analyzed with general linear mixed model ANOVAs for repeated measures to primarily test the main effects of each amino acid and their interactions. The supplementation of the amino acids was conducted from 2 to 70 days postpartum. Overall, milk production tended to be higher in the MET and in the LYS × MET group when compared to the control group. Furthermore, CON produced significantly less milk protein (kg) and milk fat (kg) than the LYS, MET, and LYS × MET groups. Milk urea tended to be lower during the entire study in the CON group than the rest of the groups. There was a trend for a reduction in the losses of postpartum body weight in the LYS × MET than the CON. In conclusion, RP methionine and lysine improved milk fat and protein yield in grazing multiparous cows with fall parturitions; consequently, both RP amino acids can be used as a strategy for improving grazing cows' production performance. [ABSTRACT FROM AUTHOR]

The purpose of the current study was to investigate the effect of gestation length (GL) on productive performance, and the incidence of calving and reproductive diseases in Holstein dairy cows. In total, 3800 Holstein singleton cows (2000 heifers and 1800 cows) from two commercial dairy farms were used. The average gestation length for 3800 cows was 276 ± 6 d. Cows with GL shorter or longer than 3 SD from the mean were removed and considered outliers. This process led to the elimination of 20 cows from the 3800 cows enrolled in the study. Therefore, 3780 cows (1994 heifers and 1786 cows) remained for data analysis, with a range of GL between 258 and 294 d. The mean of GL for the remaining 3780 cows in the study was 276 ± 5 d, which were classified as short (SGL; more than 1SD less than the population mean, mean = 267, range 258–270 d), average (AGL; population mean ± 1SD, mean = 276, range 271–281 d), and long (LGL; more than 1SD greater than the population mean, mean = 284, range 282–294 d) gestation length. In primiparous cows, the incidence of stillbirth, retained placenta, metritis, and clinical endometritis were higher in the SGL cows than in the AGL cows, but the incidence of dystocia was similar across groups. In multiparous cows, the incidence of dystocia, retained placenta, and metritis were higher in the SGL cows than in the AGL cows, and the incidence of stillbirth was higher in the SGL and LGL cows than in the AGL cows. In primiparous cows, milk yield was not different across groups. However, in multiparous cows, the SGL cows had lower milk yield than the AGL cows. In primiparous cows, the SGL cows had lower colostrum production than the AGL cows, but in multiparous cows, there was no difference in colostrum production across groups. In general, cows with either short or long gestation length had impaired health and production, but this impact was more pronounced in cows with short gestation length. • The primiparous cows with short gestation length had higher incidence of stillbirth, retained placenta, metritis, and endometritis. • The multiparous cows with short gestation length had higher incidence of dystocia, retained placenta and metritis. • The incidence of stillbirth was higher in short and long gestation length cows than average gestation length cows. • The multiparous cows with short gestation length had lower milk yield than cows with average gestation length. • The primiparous cows with short gestation length had lower colostrum than cows with average gestation length. [ABSTRACT FROM AUTHOR]

Simple Summary: The effect of increasing metabolizable protein supply (85%, 100%, and 115% of requirement) on milk production, energy and nitrogen (N) utilization, and enteric methane (CH4) emissions of Ayrshire and Holstein cows was investigated in this study. Although Ayrshire cows consumed less dry matter and produced less milk than Holstein cows, feed efficiency (kg energy-corrected milk/kg of dry matter intake), CH4 emission intensity (g/kg milk), and urinary N excretion (g/100 g N intake) did not differ between the two breeds. Energy-corrected milk increased and N use efficiency (g N milk/100 g N intake) decreased with increasing metabolizable protein supply, whereas CH4 emissions were unaffected by metabolizable protein supply. In North America, the nutrient requirements of dairy cattle are predicted using the Cornell Net Carbohydrate and Protein System (CNCPS) or the National Research Council (NRC). As Holstein is the most predominant dairy cattle breed, these models were developed based on the phenotypic, physiological, and genetic characteristics of this breed. However, these models may not be appropriate to predict the nutrient requirements of other breeds, such as Ayrshire, that are phenotypically and genetically different from Holstein. The objective of this study was to evaluate the effects of increasing the metabolizable protein (MP) supply using CNCPS on milk performance, ruminal fermentation, apparent total-tract digestibility, energy and N utilization, and enteric methane production in Ayrshire vs. Holstein lactating dairy cows. Eighteen (nine Ayrshire; nine Holstein) lactating cows were used in a replicated 3 × 3 Latin square design (35-d periods) and fed diets formulated to meet 85%, 100%, or 115% of MP daily requirement. Except for milk production, no breed × MP supply interaction was observed for the response variables. Dry matter intake (DMI) and the yields of energy-corrected milk (ECM), fat, and protein were less (p < 0.01) in Ayrshire vs. Holstein cows. However, feed efficiency and N use efficiency for milk production did not differ between the two breeds, averaging 1.75 kg ECM/kg DMI and 33.7 g milk N/100 g N intake, respectively. Methane yield and intensity and urinary N also did not differ between the two breeds, averaging 18.8 g CH4 /kg DMI, 10.8 g CH4 /kg ECM, and 27.6 g N/100 g N intake, respectively. Yields of ECM and milk protein increased (p ≤ 0.01) with increasing MP supply from 85% to 100% but no or small increases occurred when MP supply increased from 100 to 115%. Feed efficiency increased linearly with an increasing MP supply. Nitrogen use efficiency (g N milk/100g N intake) decreased linearly (by up to 5.4 percentage units, (p < 0.01) whereas urinary N excretion (g/d or g/100 g N intake) increased linearly (p < 0.01) with an increasing MP supply. Methane yield and emission intensity were not affected by MP supply. This study shows that feed efficiency, N use efficiency, CH4 (yield and intensity), and urinary N losses did not differ between Ayrshire and Holstein cows. Energy-corrected milk yield and feed efficiency increased, but N use efficiency decreased and urinary N losses increased with increasing dietary MP supply regardless of breed. Ayrshire and Holstein breeds responded similarly to increasing MP levels in the diet. [ABSTRACT FROM AUTHOR]

Anticoagulants, such as ethylenediaminetetraacetic acid (EDTA), sodium citrate (Na-citrate), or heparin are normally used in hematological clinical tests to prevent coagulation. Although anticoagulants are fundamental for the correct application of clinical tests, they produce adverse effects in different fields, such as those involving specific molecular techniques; for instance, quantitative real time polymerase chain reactions (qPCR) and gene expression evaluation. For this reason, the aim of this study was to evaluate the expression of 14 genes in leukocytes that were isolated from the blood of Holstein cows, and which were collected in Li-heparin, K-EDTA, or Na-citrate tubes; then, they were analyzed using qPCR. Only the SDHA gene showed a significant dependence (p ≤ 0.05) on the anticoagulant that was used with the lowest expression; this was observed in Na-Citrate after being compared with Li-heparin and K-EDTA (p < 0.05). Although a variation in transcript abundance with the three anticoagulants was observed in almost all the investigated genes, the relative abundance levels were not statistically significant. In conclusion, the qPCR results were not influenced by the presence of the anticoagulant; thus, we had the opportunity to choose the test tube that was used in the experiment without interfering effects impacting the gene expression levels caused by the anticoagulant. [ABSTRACT FROM AUTHOR]

Simple Summary: Milk urea nitrogen concentration varies between and within cattle breeds. The variation is thought to be mainly influenced by dietary protein intake. For this reason, proposals have been made to utilize milk urea nitrogen concentration to monitor the protein nutrition of cattle. The impact of environmental factors on milk urea nitrogen concentration is unknown. Extreme concentrations (too low or too high) of milk urea nitrogen are associated with poor reproductive performance in cows. This study investigated the effect of ambient temperature and humidity on milk urea nitrogen concentration of cows. Temperature and humidity on the day of milk sampling were positively associated with milk urea nitrogen concentration. Temperature had a significant influence on measured urea nitrogen concentration, and for this reason, it should always be considered and accounted for when milk urea nitrogen concentration data are used to make inferences about the dietary management of cows or when identifying cows that might be at risk of poor reproductive performance caused by having extreme milk urea nitrogen concentrations. Different rations should be formulated for winter and summer to keep the milk urea nitrogen concentrations within acceptable limits. This study investigated the effect of ambient temperature and humidity on milk urea nitrogen (MUN) concentration in Holstein cows. Meteorological data corresponding to the dates of milk sampling were collected over six years. A linear mixed-effects model including a random effect term for cow identification was used to assess whether temperature and humidity were predictive of MUN concentration. Age, days in milk, temperature humidity index (THI), ration, milk yield, parity and somatic cell count were also evaluated as main effects in the model. A general linear model including all variables as random effects was then fitted to assess the contribution of each variable towards the variability in MUN concentration. Maximum daily temperature and humidity on the sampling day were positively associated with MUN concentration, but their interaction term was negatively associated, indicating that their effects were not independent and additive. Variables that contributed the most to the variability of MUN concentration were dietary crude protein (21%), temperature (18%) and other factors (24%) that were not assessed in the model (error term). Temperature has a significant influence on urea nitrogen concentration and should therefore always be considered when urea nitrogen concentration data are used to make inferences about the dietary management of dairy cows. [ABSTRACT FROM AUTHOR]

Implementing a fertility protocol such as Double-Ovsynch (DO) in commercial dairy farms represents an opportunity to improve reproductive performance. However, no studies have tested this protocol nor identified factors that impact the first service conception rate (1SCR) in technified farms in the highlands of western Mexico. The objective was to identify factors that impact 1SCR in cows synchronized with the DO protocol. Records from 4759 cows synchronized for their first service with the DO protocol were used. To identify the factors that impact 1SCR, multiple logistic regression analyses were performed with the main effects: days in milk to first service, milk production at the peak of lactation, parity, calving assistance, service season of the year, sex of the calf, retained fetal membranes, metritis, and stillborn calf. The factors identified for 1SCR were the linear effect of days in milk to first service, service season, parity, retained fetal membranes, and metritis (P<0.05). Cows artificially inseminated during the summer had lower 1SCR compared to cows bred at other seasons of the year (P<0.05). The service season with the highest 1SCR was winter, with 42.5% (P<0.05). Multiparous cows showed a lower 1SCR compared to primiparous cows (29.9 and 47.3%, respectively; P<0.001). Cows with retained fetal membranes or cows with metritis had a lower 1SCR than those without these pathologies (P<0.05). In conclusion, multiparous cows, retained fetal membranes, metritis, and the summer service season are factors that negatively impact the 1SCR in cows synchronized with the DO protocol. [ABSTRACT FROM AUTHOR]

To evaluate various influencing factors of rumination time (RT) variation in Holstein cattle in China, data from 38 consecutive months from 864 lactating cows using three-axis accelerometer based wearable neck sensors were collected. Year, season, parity, THI, bihourly rumination time in minutes (R2h), and days in milk (DIM) had a significant effect on the diurnal rhythm of rumination. The average daily rumination time in minutes (DRT) was 527, increased in spring (550), and declined in summer (514). A prenatal decline in DRT from 557 at −18DIM to 344 at DIM0 and its gradual rise (597) on DIM4, gave valuable insights regarding periparturient management. A stable return of DRT was observed by DIM30, later rumination time gradually decreased with increasing DIM. From 22:00 to 04:00 the R2h was higher and had a strong correlation (0.45) with DRT. Milking and feeding time drop in R2h pattern, though significant (P < 0.05), was consistent between concerning parity and season. The average DRT of the first parity cows was lower (29 min/d) than multiparous cows, while this difference was greater (47 min d−1) in summer. DRT reached the highest daily average upon THI63–65, decreased gradually in winter, and touched the lowest during extreme summer. A chronological influencing concomitance of THI63 and THI68 with the RT of dairy cows provided valuable insights into THI thresholds for RT decline and heat stress. RT was maximum at THI63, while higher the duration spent above the THI thresholds of 68 and 72, more pronounced was the RT decline. • Three-axis accelerometer-based wearable reliably predicts the rumination behaviour. • Daily rumination time (DRT) is lower in summer months, cooling measures helps. • DRT of primiparous dairy cows is higher than multiparous cows. • DRT decline sharply around parturition and rise back to maximum at day 4. • DRT is highest at THI 63–65, decrease at THI 68 and declines markedly after THI 72. [ABSTRACT FROM AUTHOR]

The results of the assessment of animals by exterior type, taking into account the structure of their genotype, are presented. The work uses theoretical analysis, formulation of hypotheses, genealogical, biometric and statistical methods, assessment by type and productive qualities of animals. The goal is to conduct a comparative characterization of the firstborns of different genotypes according to the exterior, to determine the variability of the evaluated traits and their relationship with milk productivity. The first-born cows of the Ukrainian red-spotted and black-spotted dairy breeds and crosses obtained from the Norwegian breed had high growth indicators, with well-developed breasts in depth, width and girth. First-borns obtained from breeders of the Montbeliardee breed were inferior to peers obtained from Holstein bulls by height in the withers and sacrum oblique length of the body. However, they prevailed in the measurements of depth, width and girth of the chest, width at the withers and buttocks. Average values indices the body structure of first-born cows is typical for dairy-type animals. The shape of the udder of cows had an effect on the quantitative expression of milk productivity traits. Quality indicators of milk depended on genotype and breed. [ABSTRACT FROM AUTHOR]

The impact of genomic epistasis effects on the accuracy of predicting the phenotypic values of residual feed intake (RFI) in U.S. Holstein cows was evaluated using 6215 Holstein cows and 78,964 SNPs. Two SNP models and seven epistasis models were initially evaluated. Heritability estimates and the accuracy of predicting the RFI phenotypic values from 10-fold cross-validation studies identified the model with SNP additive effects and additive x additive (AxA) epistasis effects (A + AxA model) to be the best prediction model. Under the A + AxA model, additive heritability was 0.141, and AxA heritability was 0.263 that consisted of 0.260 inter-chromosome AxA heritability and 0.003 intra-chromosome AxA heritability, showing that inter-chromosome AxA effects were responsible for the accuracy increases due to AxA. Under the SNP additivemodel (A-onlymodel), the additive heritability was 0.171. In the 10 validation populations, the average accuracy for predicting the RFI phenotypic values was 0.246 (with range 0.197--0.333) under A + AxA model and was 0.231 (with range of 0.188--0.319) under the A-only model. The average increase in the accuracy of predicting the RFI phenotypic values by the A + AxA model over the A-only model was 6.49% (with range of 3.02--14.29%). Results in this study showed AxA epistasis effects had a positive impact on the accuracy of predicting the RFI phenotypic values when combined with additive effects in the prediction model. [ABSTRACT FROM AUTHOR]

Cattle methane emissions (ME) account for approximately 6% of global anthropogenic greenhouse gas emissions. Given the challenges in measuring ME directly from individual animals, there is a need for the development of novel indirect methods. Rumination time (RT) and milk mid-infrared spectral data (MIR) show promise for the indirect assessment of ME in dairy cows. Both traits have been used as indicators of reproduction, production, and gas emission traits. Methodologies combining the use of MIR and machine learning algorithms such as artificial neural networks (ANN) for the prediction of ME have been successful; however, the inclusion of RT has not been assessed. This study aimed to evaluate the impact of RT on milk MIR-based models using ANN for the prediction of ME. One-week averages for RT, ME, and MIR from first-lactation Canadian Holstein cows (n = 412) were calculated. Six data sets were evaluated using a multilayer perceptron ANN. All sets included age at calving, season of calving and days in milk as model factors, but varied in using milk MIR data points (1,060 or 235) and including or not including RT. The ANN architecture consisted of one input layer, one hidden layer with one or more neurons, and one output layer. Results showed that sets using both RT and milk MIR data achieved correlations from 0.5 to 0.6 between predicted and observed ME. Notably, the inclusion of RT did not improve the performance of the models. Predictions may be improved through the use of larger data sets, the use of daily records, and inclusion of data across herds and lactations. Optimizing parameters of the ANN could also improve predictions. Further research is needed to fully assess the potential of RT as a predictor of ME in dairy cows. [ABSTRACT FROM AUTHOR]

Background: No studies have been conducted evaluating sugarcane silage associated with both Lactobacillus plantarum and Pediococcus pentosaceus for lactating dairy cows. Objective: To evaluate diets containing different roughages with and without microbial inoculants on intake, digestibility and milk yield of medium-producing cows. Methods: A total of 15 Holstein cows distributed into a randomized block design were used. Dietary treatments were: 1) a corn silage-based diet (CS), 2) a fresh sugarcane-based diet (SC), 3) a sugarcane silage ensiled without inoculant (SS), 4) sugarcane silage ensiled with Lactobacillus buchneri (SSLB), and 5) sugarcane silage ensiled with Lactobacillus plantarum and Pediococcus pentosaceus (SSLP). Results: Digestible organic matter intake (DOMI) was lower (p

Ketosis is a major metabolic disorder that can lead to huge economic losses in postpartum dairy cows by influencing milk production and reproduction performance. Therefore, it is very important to understand the characteristics and significance of plasma GH levels and dynamic changes in postpartum dairy cows for finding pathogenesis of subclinical ketosis (SK). The present study aimed to determine the role of growth hormone (GH) from the onset of SK to the fifth week postpartum and to explain the variations in GH, and metabolic markers namely, β-hydroxybutyric acid (BHBA), non-esterified fatty acid (NEFA) and glucose (GLU) at early and later SK stages in postpartum Holstein cows. A 5-wk test and an intraday 12-h test were conducted in postpartum Holstein cows. Both tests were carried out every three hours from 10:00–22:00 for 7–14 days postpartum (12-h test: n = 16) to determine plasma concentrations of GH, BHBA, NEFA and GLU. The 5-wk test results showed that GH, BHBA and NEFA concentrations were significantly higher in the SK group during the five-weeks postpartum (p < 0.01); GLU concentration was significantly lower in the SK group (p < 0.01). Intraday 12-h test results revealed that the feeding time affected the plasma concentrations of GH, BHBA, NEFA and GLU. After 1-h of feeding time, GH concentrations decreased, while BHBA, NEFA and GLU concentrations increased. After 4-h of feeding time GH, BHBA and NEFA had the highest plasma concentrations, and GLU the lowest. In both experiments, GH was positively correlated with BHBA, NEFA, and negatively correlated with GLU. It can be suggested that GH has a potential role in development and aetiology of subclinical ketosis. [ABSTRACT FROM AUTHOR]

Simple Summary: Pregnancy losses in dairy cattle result in impaired animal health and welfare, as well as economic losses due to increased culling, reduced milk production, calf losses, and increased reproductive costs, among others. Advances in the last few decades have allowed the dairy industry to make significant progress in reproductive efficiency, but pregnancy losses continue to be an unresolved problem. The origin of abortions can be infectious disease, metabolic disorders, heat stress, and a genetic predisposition among many others. We have developed genomic predictions (Z_Abort) to identify Holstein dairy cows with a greater risk of abortion. This allows dairy producers and veterinarians to select more productive and profitable cows. The objectives of the study were to (1) describe the development of the genomic predictions for cow abortions in lactating Holstein dairy cattle based on producer-recorded data and ssGBLUP methodology and (2) evaluate the efficacy of genomic predictions for cow abortions in commercial herds of US Holstein cows using data from herds that do not contribute phenotypic information to the evaluation. The results of the present study show that the genomic predictions for cow abortion trait (Z_Abort) can effectively predict the risk of abortion of lactating Holstein dairy cows and, hence, allow genetic selection towards healthier and more profitable cows. Abortion in dairy cattle causes great economic losses due to reduced animal health, increase in culling rates, reduction in calf production, and milk yield, among others. Although the etiology of abortions can be of various origins, previous research has shown a genetic component. The objectives of this study were to (1) describe the development of the genomic prediction for cow abortions in lactating Holstein dairy cattle based on producer-recorded data and ssGBLUP methodology and (2) evaluate the efficacy of genomic predictions for cow abortions in commercial herds of US Holstein cows using data from herds that do not contribute phenotypic information to the evaluation. We hypothesized that cows with greater genomic predictions for cow abortions (Z_Abort STA) would have a reduced incidence of abortion. Phenotypic data on abortions, pedigree, and genotypes were collected directly from commercial dairy producers upon obtaining their permission. Abortion was defined as the loss of a confirmed pregnancy after 42 and prior to 260 days of gestation, treated as a binary outcome (0, 1), and analyzed using a threshold model. Data from a different subset of animals were used to test the efficacy of the prediction. The additive genetic variance for the cow abortion trait (Z_Abort) was 0.1235 and heritability was 0.0773. For all animals with genotypes (n = 1,662,251), mean reliability was 42%, and genomic predicted transmitting abilities (gPTAs) ranged from −8.8 to 12.4. Z_Abort had a positive correlation with cow and calf health traits and reproductive traits, and a negative correlation with production traits. Z_Abort effectively identified cows with a greater or lesser risk of abortion (16.6% vs. 11.0% for the worst and best genomics groups, respectively; p < 0.0001). The inclusion of cow abortion genomic predictions in a multi-trait selection index would allow dairy producers and consultants to reduce the incidence of abortion and to select high-producing, healthier, and more profitable cows. [ABSTRACT FROM AUTHOR]

Dairy cattle must allocate energy to milk production and reproduction. Therefore, understanding the environmental factors that affect conception rates in nulliparous and primiparous cows is helpful in appropriate feeding management strategies before and after calving. Accordingly, the aim of this study was to investigate the influence of environmental factors before and after the first calving on the conception rate, representing the starting point of milk production. The records of the first artificial insemination (AI) from Holstein nulliparous cows (n = 533,672) and primiparous cows (n = 516,710) in Hokkaido, Japan, were analyzed using separate multivariable logistic regression models. The mean conception rates for nulliparous and primiparous cows from 2012 to 2018 were 55.2 and 39.2%, respectively. In both nulliparous and primiparous cows, the conception rate of crossbreeding using Japanese Black (JB) semen was significantly higher than that for purebred Holstein breeding. The conception rate using sexed semen decreased in the warmer months only in nulliparous cows. Moreover, we grouped primiparous cows according to milk yield during peak lactation (PY; < 25, 25–30, 30–35, ≥35 kg) and the interval from calving to first insemination (CFI; < 60, 60–79, 80–99, ≥100 d), and evaluated their combined effect on the conception rate. Both PY and CFI strongly affected the conception rate in primiparous cows, which decreased with an increase in PY, even for the group with CFI ≥100 d; however, the conception rate increased for a CFI ≥60 d regardless of PY. Taken together, this study demonstrates the long-term effect of PY and an independent effect of CFI on the conception rate of cows. These results provide guidance for management to execute appropriate AI implementation strategies before and after lactation. [ABSTRACT FROM AUTHOR]

Simple Summary: The fertility of a dairy cow can be described as the female's ability to conceive and maintain pregnancy when insemination is performed at the proper time relative to ovulation. In this context, poor estrous detection and embryonic or fetal losses are common causes for reduced reproductive performance in dairy cows. Furthermore, heat stress severely deteriorates conception and pregnancy rates in dairy farms. The aim of this study was to see how oral folic acid (FA) supplements affect progesterone levels, blood metabolites, endocrine patterns, and blood biochemical concentrations in heat-stressed pregnant cows. Oral FA supplementation (10 μg kg−1) in the first month of gestation improved the progesterone profile, as well as blood folates, pregnancy associated glycoprotein (PAG), growth hormone (GH), and Insulin-like growth factor-1 (IGF-1) concentrations in heat-stressed Holstein cows. The aim was to elucidate the impact of oral folic acid (FA) supplements on progesterone profile, blood metabolites and biochemical indices of heat-stressed Holstein cows during the early stage of pregnancy. The study lasted from the day of artificial insemination through the end of the fourth week of pregnancy. The first group (CON, n = 17) received 0 μg of FA/kg BW as a control. The second and third groups received oral FA doses of 5 (FA5, n = 19) and 10 (FA10, n = 20) μg kg−1 BW, respectively. At the 2nd and 3rd weeks of pregnancy, the FA10 group had greater progesterone levels than the CON group (p < 0.05). The FA10 group had a greater progesterone level than the FA5 and CON groups at the fourth week of pregnancy (p < 0.01). The FA10 group had higher folate levels than CON group during the first three weeks of pregnancy (p < 0.01). Both FA-supplemented groups had significantly greater serum folates than the CON group by the end of the fourth week of pregnancy (p < 0.01). At the 2nd and 4th weeks of pregnancy, the FA10 group had greater levels of serum glucose and globulin than the CON group (p = 0.028 and 0.049, respectively). Both FA-supplemented groups had greater serum growth hormone (GH) levels at the 4th week of pregnancy (p = 0.020). Additionally, the FA10 group showed significantly higher levels of IGF-1 at the 2nd and 4th week of gestation (p = 0.040 and 0.001, respectively). FA supplementation decreased the levels of non-esterified fatty acid (NEFA) at the 2nd and 4th week of gestation (p = 0.020 and 0.035, respectively). Additionally, the FA10 group showed significantly higher pregnancy-associated glycoprotein (PAG) levels at the 2nd and 4th week of gestation (p = 0.005 and 0.001, respectively). In conclusion, oral FA supplementation (10 mcg kg−1) in the first month of gestation improved the progesterone profile, as well as blood folates, PAG, GH, and IGF-1 concentrations in heat-stressed Holstein cows. These findings could be useful in developing practical strategies to keep dairy cows' regular reproductive patterns under heat stress conditions. [ABSTRACT FROM AUTHOR]

Simply Summary: Mastitis disease causes huge losses for the dairy industry worldwide. The molecular markers have been shown to be a promising tool for the diagnosis of mastitis infections and the selection of animals with better mastitis resistance. In this study, we surveyed the mastitis incidence in Vietnamese Holstein cows. We also examined the association of polymorphisms in Lactoferrin (LTF) and Toll-like receptor 2 (TLR2) genes with mastitis score and milk component traits. Our results indicated that the interaction between TLR2 genotypes and diseases has a significant impact on the fat and protein percentage of mink. Therefore, TLR2 polymorphism could be used for the selection of cows with better milk compositions. Mastitis is one of the most widespread diseases in dairy cows and causes huge losses for the dairy industry. Molecular markers can be used for the quick diagnosis of mastitis infection, consequently reducing the loss caused by this disease. Lactoferrin (LTF) and Toll-like receptor 2 (TLR2) have been suggested as candidate genes for mastitis; however, their associations with the mastitis incidence and milk components have not been reported in Vietnamese Holstein cows. This study examined the association of TLR2 and LTF polymorphisms with subclinical mastitis and milk components in the Holstein breed raised in Vietnam. Among 192 samples, we identified 44 mastitis-positive samples (22.92%). The mastitis significantly reduced the fat and lactose components in milk (p < 0.001) but increased the protein concentration in milk. A total of 94 (49%) and 98 (51%) cows had AA and AB genotypes for the LTF gene, respectively. No significant association was found between the LTF genotypes and the milk component traits or mastitis incidence (p > 0.05). The interaction between LTF and mastitis incidence was significantly associated with the protein percentage (p = 0.01). A total of 78, 76, and 38 cows had genotypes GG, GT, and TT for the TLR2 gene, respectively. TLR2 genotypes were not significantly associated with mastitis incidence (p > 0.05) but were significantly associated with pH value (p = 0.03). The interaction between TLR2 and mastitis incidence was significantly associated with the fat (p = 0.02) and protein percentage (p = 0.04). Further studies are required to confirm the roles of LTF and TFL2 in mastitis in the Holstein breed in Vietnam. [ABSTRACT FROM AUTHOR]

Milk urea content is receiving growing interest from science and industry as a tool to infer the protein adequacy of dairy cows' diets, nitrogen excretion and its environmental impact, and efficiency of animals' protein metabolism. Fourier-transform infrared (FTIR) prediction is a high-throughput method for rapidly and cheaply evaluating milk urea content at the population level. Existing knowledge of the major sources of variation (e.g., year, season, farming system, individual herd, and the cow's breed, parity, stage of lactation, and productive potential) is fragmentary. The objective of this work was to study at the population level the simultaneous effects of all the major sources of variation and their most important interactions. Milk urea content in 1,759,706 test day milk samples collected from 291,129 lactations of 115,819 cows from 6,430 herds over 8 yr was predicted by FTIR. The milk urea content data (and also milk protein percentage, for comparison) were analyzed using a linear model that included the effects of parity, days in milk (DIM) class, year, month, herd intensiveness level, cow productivity level, breed, and herd intensiveness and cow productivity levels within breed. All sources of variation of milk urea content proved highly significant, the most important in terms of F -value being breed > year > herd intensiveness level > parity. The ranking for milk protein was very different (DIM class > herd intensiveness level > parity > breed). The patterns of the least squares means for urea and protein contents of milk were also very different and sometimes contrasting. The seasonal variation in urea was sinusoidal. Urea content increased during the first 4 mo of lactation and then remained almost stable before decreasing after 11 mo. Specialized dairy breeds had lower average milk urea content than dual-purpose breeds; in the former case it was lower in Holsteins than in Brown Swiss, and in the latter it was lower in Simmentals than in Alpine Greys. The effect of herd intensiveness level was much stronger than the effect of cow productivity level; the increase in milk urea with increasing herd average daily milk yield was almost linear in the case of dairy breeds but curvilinear in dual-purpose breeds. The large differences in breed and the modest relationships with the cow's productive potential require further analysis at the genetic level to obtain information of potential use in genetic improvement of the dairy cow populations. [ABSTRACT FROM AUTHOR]

Context: There is a large gap between developed and developing countries in the field of genetic evaluation of livestock animals. Introduction of genomic evaluation procedures and methods could contribute to reducing this gap. Aims: The goal of this study was to select a reference cow population for the Holstein breed in Tunisia. Specific objectives were to update adjustments for non-genetic factors affecting milk yield, estimate genetic parameters for milk yield, and predict cow breeding values. Methods: A BLUP animal model was used for 11 175 lactations recorded between 2012 and 2017 from 6251 dairy cattle raised in 33 Holstein dairy herds from three types of herds or production sectors. A pedigree file of 16 211 males and females was included in the genetic evaluation. Multiplicative adjustment factors were computed for age and month of calving, using adjusted 305 days in milk. Key results: Month of calving, age at calving and farm ownership were significant sources of variation for milk yield. Cows calving in autumn and early winter (September–January) yielded more milk than those calving in spring (February–May) by 430 kg, and summer (June–August) by 455 kg. Holstein cows in Tunisia reached their maximum milk yield during the fourth lactation. Average adjusted milk yield for days in milk, month and age of calving was 6621 ± 2883 kg. Heritability estimates of adjusted milk yield were 0.14 ± 0.02 for all seven lactations and 0.16 ± 0.03 for the three first lactations. Phenotypic correlations among lactations were all positive, ranging from 0.25 to 0.43. On the basis of two main traditional designs (extreme yield and top accuracy), 1000 cows were selected to form the Tunisian female reference population. Conclusion: The first step of genomic evaluation has been realised by forming a reference population from cows selected for adjusted milk yield production, based on their predicted breeding values and accuracies, using a BLUP animal model. Implication: In the absence of progeny testing and sufficient proven sires, a cow reference population could represent the alternative for implementing genomic selection in developing countries. A reference population of Holstein cows was selected for milk yield production, by using lactation records from Tunisian dairy herds and BLUP modelling. Following the steps described in this study, researchers in developing countries will be able to identify a reference population toward genomic evaluation even without a progeny testing scheme. [ABSTRACT FROM AUTHOR]

The specific fatty acid (FA) profile of colostrum may indicate a biological requirement for neonatal calves. The objective of this study was to characterize the FA profile and yields in colostrum, transition milk, and mature milk in primiparous (PP) and multiparous (MP) cows. Colostrum was milked from 10 PP and 10 MP Holstein cows fed the same pre- and postpartum rations. Milkings (M) 2 to 5 and 12 were respectively termed transition and mature milk. Overall, short-chain FA (C4:0 and C6:0) were 61 and 50% lower in colostrum than mature milk, respectively. A parity by milking interaction was also present, with higher C4:0 for PP cows at M2 and for MP cows at M12. Additionally, higher concentrations of C6:0 were present for PP cows at M2 through M4 and for MP cows at M12. Palmitic (C16:0) and myristic (C14:0) acids were 38% and 19% higher in colostrum than mature milk, respectively. However, total saturated FA remained relatively stable. Branched-chain FA were 13% lower in colostrum than mature milk and higher in PP than MP cows throughout the milking period. The proportion of trans -monounsaturated FA (MUFA) was 72% higher in PP cows throughout the milking period, as well as 13% lower in colostrum than mature milk. In contrast, cis -MUFA and total MUFA were not affected by milking nor parity. Linoleic acid (LA) was 25% higher in colostrum than transition and mature milks, but α-linolenic acid (ALA) did not differ. Consequently, the ratio of LA to ALA was 29% higher in colostrum than mature milk and 33% higher in MP cows. Linoleic acid was also 15% higher in MP cows, whereas ALA was 15% higher in PP cows. Conjugated linoleic acid (CLA, cis -9, trans -11) was 2.7-fold higher in PP cows, and no differences between colostrum and mature milk were detected. Overall, polyunsaturated FA (PUFA) from the n-6 and n-3 series were over 40% higher in colostrum compared with transition and mature milk. Milking by parity interactions were present for arachidonic acid (ARA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), and total n-3 PUFA, translating to higher proportions in PP cows in M1 to M3, whereas proportions remained relatively stable throughout the milking period in MP cows. Despite increasing milk yields throughout the subsequent milkings, higher yields of EPA, ARA, DPA, and DHA were present in colostrum than in mature milk. Greater proportions and yields of n-3 and n-6 FA in colostrum may translate to specific requirements for newborn calves. Differences were also observed between PP and MP cows and may reflect different nutrient requirements and partitioning. [ABSTRACT FROM AUTHOR]

Background: Variables associated with body tissue mobilization place dairy cows at greater risk of reproductive failure. Objective: To investigate the association between blood metabolites and body condition score (BCS) at the beginning of lactation and the reproductive efficiency and milk yield of Holstein cows in a hot environment. Methods: In total, 165 Holstein cows were selected for the study from which blood samples were taken to determine the concentration of various blood metabolites and their association with the reproductive efficiency and milk yield. Results: Cows with serum β-hydroxybutyrate (BHBA) ≤0.8 mmol/L one week postpartum were 3.3 times more likely to become pregnant at first service, and 2.2 times more likely to become pregnant before 80 d postpartum than cows with higher serum BHBA levels. The odds (OR 2.7; 95% CI 1.3–5.4; p15 mg/dL, creatinine 0.40 units of BCS loss during the first 30 d postpartum were critical threshold that predicted the likelihood of 305-d milk yield higher than 10,500 kg. Conclusions: Serum BHBA and creatinine one wk after calving as well as BCS 30 and 60 d post-calving provided reasonably accurate cut-off screening values to discriminate cows with better reproductive performance and higher 305-d milk yield.

The aim of this study was to determine the effects of κ-casein, β-lactoglobulin, prolactin, and DGAT1 (diacylglycerol acyltransferase1) gene polymorphisms on milk yields in Holstein cows raised in Antalya province, Turkey. A total of 517 cows were genotyped by the PCR-RFLP method to detect κ-casein/HinfI, β-lactoglobulin/HaeIII, prolactin/RsaI, and DGAT1/Cfr1 polymorphisms. In the study, two types of alleles were identified as A and B for κ-casein, β-lactoglobulin, and prolactin loci, while K and A alleles were detected for DGAT1 locus. The frequencies of A and B allele were calculated as 0.8279 and 0.1721 for κ-casein, 0.4662 and 0.5338 for β-lactoglobulin, 0.8762 and 0.1238 for prolactin, respectively. The frequencies of the K and A allele were 0.6441 and 0.3559 for DGAT1. The studied population was found to be in Hardy-Weinberg equilibrium for all of the loci. Association analysis revealed a significant effect of prolactin-RsaI polymorphism on milk yield (p < 0.05) in which animals with the B allele showed superior value than the A allele. On the other hand, no statistically significant relation effects of κ-casein-HinfI, β-lactoglobulin-HaeIII, and DGAT1-CfrI polymorphisms on milk yield were observed (p > 0.05). It would be beneficial to increase the number of studies that determine the variation of existing genes and investigate the effects of these polymorphisms on milk yield characteristics in Holstein cattle. Thus, obtained results can be used as a selection criterion in marker-assisted selection programs. [ABSTRACT FROM AUTHOR]

Only a few, principal, weather stations in Japanese prefectures have the daily humidity records required to calculate the temperature–humidity index (THI) as a dairy cow heat-stress indicator. We compared three heat-stress indices: (1) THI calculated from daily average temperature and daily relative humidity at a principal weather station (PTHI); (2) daily average temperature at each herd’s closest local weather station (TEMP); and (3) THI calculated from daily average temperature at each herd’s closest local weather station and daily relative humidity at the principal weather station (HTHI). We used daily records from 532 provincial weather stations and test-day records of milk production from Days 6 to 305 post-first-calving in Holsteins to compare the indices as indicators of heat-stress effects on milk yield and somatic cell score (SCS). The models used the BLUPF90 package to analyze the effects of herd– year, calving age, days in milk, and PTHI, TEMP, or HTHI. We estimated each model’s mean square error (MSE) and compared suitabilities among indices for each trait. TEMP heat-stress thresholds were 〜18°C (milk yield) and 15–20°C (SCS). The MSE of the HTHI model was the smallest, but no significant differences were found among the indices for milk yield. [ABSTRACT FROM AUTHOR]

Background: No studies have been conducted evaluating sugarcane silage associated with both Lactobacillus plantarum and Pediococcus pentosaceus for lactating dairy cows. Objective: To evaluate diets containing different roughages with and without microbial inoculants on intake, digestibility and milk yield of medium-producing cows. Methods: A total of 15 Holstein cows distributed into a randomized block design were used. Dietary treatments were: 1) a corn silage-based diet (CS), 2) a fresh sugarcane-based diet (SC), 3) a sugarcane silage ensiled without inoculant (SS), 4) sugarcane silage ensiled with Lactobacillus buchneri (SSLB), and 5) sugarcane silage ensiled with Lactobacillus plantarum and Pediococcus pentosaceus (SSLP). Results: Digestible organic matter intake (DOMI) was lower (p<0.05) in cows fed SSLB (9.77 kg day-1) when compared with cows fed CS (13.29 kg day-1) and SSLP (12.42 kg day-1). Ensiling of sugarcane increased intake of neutral detergent fiber (NDF) compared to SC (mean of 6.00 kg day-1 versus 4.97 kg day-1; p<0.05). Dry matter digestibility was greater (p<0.05) in CS (77.80%) compared with diets based on sugarcane silage, whereas NDF digestibility was lower for treatments with sugarcane (p<0.05). Milk yield was similar among CS (27.99 kg), SC (25.59 kg), and silages with additives (25.47 and 27.07 for SSLB and SSLP, respectively). Cows fed CS produced more fat-corrected milk (25.89 kg) than those fed sugarcane-based diets (p<0.05). Conclusions: Fresh sugarcane or sugarcane silage with additives can be used as a roughage source for dairy cows producing up to 23.43 kg d-1 fat-corrected milk, considering the total diet is properly balanced. [ABSTRACT FROM AUTHOR]

Meta-analysis is a statistical method in which the results of studies conducted on a specific subject independently are evaluated together. This method aims to estimate the parameters more reliably by increasing the sample size. In this study, it was examined that the change of lameness according to lactation order in Holstein dairy cows by meta-analysis. The data obtained from different farms were assumed as the results of 34 different studies showing the change of lameness according to the lactation order, and a meta-analysis was conducted. Lameness was determined by using a lameness score scale with 5 levels. Lameness scoring with five levels was converted into binary definition as 0 for healthy cows (cows with lameness score 1 or 2) and 1 for lame cows (cows with lameness score 3, 4 or 5). One-Step (Peto) Method for odds ratio and Q test statistic for determination of heterogeneity among studies were used. Odds ratio obtained from different studies are combined with fixed effect model and overall odds ratio was found significant (P<0.001) with level of 0.574 which means lameness in the first lactation is 0.574 times less likely than in the second lactation. It was determined that the 95% confidence interval for this ratio ranged from 0.387 to 0.852. As a result, it was revealed by meta-analysis that there is a relationship between lactation order and lameness level in cattle and that the risk of lame in cattle in the first lactation is lower than in the second lactation. Although meta-analysis is a method that is becoming widespread in every field, it is more widely used in the field of health sciences, where there are some restrictions in increasing the number of observations in individual studies due to the use of human resources in their studies. It is thought that the obtained study results will contribute to introduce of meta-analysis in discrete data and widely use in animal husbandry. [ABSTRACT FROM AUTHOR]

Normal lactation records of 1717 Holstein cows belong to commercial dairy farm covered a period of 11 years from 1995 to 2005 were used in this study to evaluate the effects of calving season and parity on reproductive performance under subtropical desert conditions. The reproductive traits studied were age at first calving (AFC, month), first service period (FSP, day), number of services per conception (NSC, number), days open (DO, day), calving interval (CI, month), projected minimum calving interval (PMCI, month), breeding interval (BI, day) and conception rate (CR, %). NSC, DO, CI, and PMCI were enhanced significantly in winter compared to summer. Also, PMCI value in winter was lower compared to summer. The overall means of FSP, DO, PMCI, and BI were lower in multiparous cows compared to those in primiparous. No influences of interaction between season of calving and parity were detected on the reproductive traits of FSP, NSC, DO, CI and PMCI. CR had been influenced by season of calving as cows calved in winter exhibited higher CR (44%) than those calved in summer (39%). Heritability estimate of NSC, DO, CI and PMCI heritabilities were low and ranged from 0.07 to 0.19. In contrast, FSP and BI had medium heritabilities. Genetic correlations were low and positive between each of NSC, FSP or BI, between CI and each of NSC or FSP. In contrast, Genetic correlations were medium to high positive among other traits. The phenotypic correlations between NSC and each of FSP or BI were negatively low. Other phenotypic correlations were mostly similar in value and direction as the corresponding genetic correlations. Genetic trends of FSP, DO, CI and PMCI exhibited clear deterioration by time. They tended to decrease throughout the years of study. In contrast NSC and BI breeding values tended to increase during the same period. [ABSTRACT FROM AUTHOR]

Contents: This study aimed to determine the effect of flunixin meglumine treatment during and after the transfer of in vivo produced embryos to Angus (cows) and Holstein (cows and heifers) breeds of cattle on pregnancy rate. Holstein cows were used as donors in the study. A double dose of prostaglandin F2α was administered to the recipient animals for synchronization. Uterine flushing was performed in donors on day 7 after artificial insemination. A total of 295 transferable embryos were obtained. These embryos were transferred to Angus cows (n = 85), Holstein heifers (n = 80) and Holstein cows (n = 130). After the transfer, these animals were divided into three subgroups. The first subgroup (TI) was administered flunixin meglumine during embryo transfer, and the second subgroup (TII) was administered flunixin meglumine both during embryo transfer and on days 8 and 9 after the transfer. The third subgroup (TIII) was not administered anything and it was considered the control group. Pregnancy examination of the recipients was performed on days 30–35 after the transfer using real‐time ultrasonography. The pregnancy rates after embryo transfer were found to be 43.52% in Angus cows, 42.5% in Holstein heifers, and 24.61% in Holstein cows (p <.05). When the animals were not classified according to breed, the pregnancy rates in subgroups TI, TII and TIII were found to be 29.29%, 45.10% and 29.79%, respectively (p <.05). In addition, the pregnancy rates were higher in TII and TIII subgroups of Angus cows and Holstein heifers compared to that of Holstein cows (p <.05). As a result, the pregnancy rates obtained after embryo transfer in Angus cows and Holstein heifers were found to be higher than that in Holstein cows. In addition, it was concluded that the administration of flunixin meglumine during and during/after embryo transfer has a positive effect on pregnancy rates in Angus cows and Holstein heifers. [ABSTRACT FROM AUTHOR]

This study investigated the effect of ambient temperature and humidity on milk urea nitrogen (MUN) concentration in Holstein cows. Meteorological data corresponding to the dates of milk sampling were collected over six years. A linear mixed-effects model including a random effect term for cow identification was used to assess whether temperature and humidity were predictive of MUN concentration. Age, days in milk, temperature humidity index (THI), ration, milk yield, parity and somatic cell count were also evaluated as main effects in the model. A general linear model including all variables as random effects was then fitted to assess the contribution of each variable towards the variability in MUN concentration. Maximum daily temperature and humidity on the sampling day were positively associated with MUN concentration, but their interaction term was negatively associated, indicating that their effects were not independent and additive. Variables that contributed the most to the variability of MUN concentration were dietary crude protein (21%), temperature (18%) and other factors (24%) that were not assessed in the model (error term). Temperature has a significant influence on urea nitrogen concentration and should therefore always be considered when urea nitrogen concentration data are used to make inferences about the dietary management of dairy cows.

Background: Variables associated with body tissue mobilization place dairy cows at greater risk of reproductive failure. Objective: To investigate the association between blood metabolites and body condition score (BCS) at the beginning of lactation and the reproductive efficiency and milk yield of Holstein cows in a hot environment. Methods: In total, 165 Holstein cows were selected for the study from which blood samples were taken to determine the concentration of various blood metabolites and their association with the reproductive efficiency and milk yield. Results: Cows with serum β-hydroxybutyrate (BHBA) ≤0.8 mmol/L one week postpartum were 3.3 times more likely to become pregnant at first service, and 2.2 times more likely to become pregnant before 80 d postpartum than cows with higher serum BHBA levels. The odds (OR 2.7; 95% CI 1.3–5.4; p<0.01) of a cow getting pregnant at first service were higher in cows with serum creatinine levels higher than 2.0 mg/dL one week postpartum than cows with lower blood levels of this metabolite. The BCS at 30 and 60 d postpartum that predicted pregnancy at first service and pregnancy to all services was 3.0. Blood urea nitrogen >15 mg/dL, creatinine <1.8 mg/dL, total protein ≤5.0 mg/dL one week postpartum, and >0.40 units of BCS loss during the first 30 d postpartum were critical threshold that predicted the likelihood of 305-d milk yield higher than 10,500 kg. Conclusions: Serum BHBA and creatinine one wk after calving as well as BCS 30 and 60 d post-calving provided reasonably accurate cut-off screening values to discriminate cows with better reproductive performance and higher 305-d milk yield. [ABSTRACT FROM AUTHOR]

Mastitis is one of the most prevalent diseases in dairy cattle and is the cause of considerable economic losses. Alongside somatic cell count (SCC), differential somatic cell count (DSCC) has been recently introduced as a new indicator of intramammary infection. The DSCC is expressed as a count or a proportion (%) of polymorphonuclear neutrophils plus lymphocytes (PMN-LYM) in milk somatic cells. These numbers are complemented to total somatic cell count or to 100 by macrophages (MAC). The aim of this study was to investigate the genetic variation and heritability of DSCC, and its correlation with milk composition, udder health indicators, milk composition, and technological traits in Holstein cattle. Data used in the analysis consisted in single test-day records from 2,488 Holstein cows reared in 36 herds located in northern Italy. Fourier-transform infrared (FTIR) spectroscopy was used to predict missing information for some milk coagulation and cheese-making traits, to increase sample size and improve estimation of the genetic parameters. Bayesian animal models were implemented via Gibbs sampling. Marginal posterior means of the heritability estimates were 0.13 for somatic cell score (SCS); 0.11 for DSCC, MAC proportion, and MAC count; and 0.10 for PMN-LYM count. Posterior means of additive genetic correlations between SCS and milk composition and udder health were low to moderate and unfavorable. All the relevant genetic correlations between the SCC traits considered and the milk traits (composition, coagulation, cheese yield and nutrients recovery) were unfavorable. The SCS showed genetic correlations of −0.30 with the milk protein proportion, −0.56 with the lactose proportion and −0.52 with the casein index. In the case of milk technological traits, SCS showed genetic correlations of 0.38 with curd firming rate (k 20), 0.45 with rennet coagulation time estimated using the curd firming over time equation (RCT eq), −0.39 with asymptotic potential curd firmness, −0.26 with maximum curd firmness (CF max), and of −0.31 with protein recovery in the curd. Differential somatic cell count expressed as proportion was correlated with SCS (0.60) but had only 2 moderate genetic correlations with milk traits: with lactose (−0.32) and CF max (−0.33). The SCS was highly correlated with the log PMN-LYM count (0.79) and with the log MAC count (0.69). The 2 latter traits were correlated with several milk traits: fat (−0.38 and −0.43 with PMN-LYM and MAC counts, respectively), lactose percentage (−0.40 and −0.46), RCT eq (0.53 and 0.41), t max (0.38 and 0.48). Log MAC count was correlated with k 20 (+0.34), and log PMN-LYM count was correlated with CF max (−0.26) and weight of water curd as percentage of weight of milk processed (−0.26). The results obtained offer new insights into the relationships between the indicators of udder health and the milk technological traits in Holstein cows. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the difference between melatonin hormone in night milk and melatonin concentration in day milk of Holstein cows. In this study, daytime milk obtained from 40 heads Holstein cows in the first lactation raised in a private dairy cattle farm in Karapınar district of Konya state province in Turkey and night milk samples taken from the same cows that were kept in darkness for one week were used. The milk samples were collected from day and night milking in order to determine the melatonin concentration with the help of Bovine Melatonin (MLT) Elisa Kit. In this study, melatonin concentration in day time and night time milk were determined as respectively 103.70 ± 6.61 pg mL-1 and 163.13 ± 8.96 pg mL-1. The difference between melatonin levels of day and night milk was statistically significant (P<0.01). Since significant difference occurred between melatonin concentration between day and night milk at the end of the study, it can be stated that night milk can be used for medical purposes that is used cure of some illnesses and producers can be provided with a new production source. [ABSTRACT FROM AUTHOR]

The aim of this study is to compare the pregnancy rates by applying embryo transfer to the cows which are not pregnant and should be removed from herd as repeat breeder. In this study, 87 randomly selected Holstein cows utilized. The repeat breeder cows (n=45) were selected from at least one giving birth, having regular sexual cycle, missing clinical worsening into genital organ and not displaying an abnormal discharge. On the other hand, it was selected from nonpregnant cows which inseminated artificially at least 3 times or more. Besides, cows that used as the control group (n=42) were selected from the cows without any artificial insemination postnatally. The PGF2α application was performed to all recipient cows which are considered to benefit from as a recipient in control and testing groups just 24 days before the flushing day. After this application, the cows showing estrous symptoms were recorded and determined as candidate recipients. The pregnancy rates were 35.6% and 50% for testing and control groups, respectively and the difference between the groups was significant (P<0,05). As a result, even this difference between the groups it has been concluded that embryo transfer can be used to conceive especially for high-yielding cows as a treatment method for repeat breeder cows. Thereby, embryo transfer from the cows with high superior characteristics to the high milk yielding cows which have infertility problems can economically be beneficial by utilizing the high milk yield in the later lactation without any replacement cost. [ABSTRACT FROM AUTHOR]

Background: Dnipropetrovsk region of Ukraine is located in the northern steppe subzone, where livestock is actively developing, including dairy farming. Cows, imported from other ecological and climatic conditions undergo appropriate acclimatization to new conditions of exploitation. The current research was based on the assessment of the adaptive properties of Holstein cows of different ages to manage and control the level of their milk productivity and reproductive function during exploitation. Methods: All researches were carried out on the milk complex of "Agro-Soyuz". The information base was data on productive qualities in individual cards of cows, results of assessment of zootechnical and veterinary accounting. To achieve this goal, an analysis was conducted from the first to the seventh lactation of Holstein cows. Result: Our researches allowed establishing the adaptability of Holstein cows of different ages in terms of ecological plasticity of the northern steppe of Ukraine. With a slight imbalance of the organism and the environment cows show high productive qualities at unsatisfactory reproductive function. This work will be a complementary the comprehensive study the adaptation of Holstein cows in different climatic conditions. [ABSTRACT FROM AUTHOR]

Brachyspina syndrome (BS) is a rare monogenic autosomal recessive hereditary disorder of the Holstein Fresian breed caused by a deletion of 3.3Kb in the Fanconi anemia complementation group I (FANCI) gene on BTA-21, which leads to a frame-shift and premature stop codon. Some of the consequences of BS are the reduction of the fertility rate and milk production. This study developed a simple, sensitive, rapid cost-effective assay method based on real time PCR and melting curve analysis for the detection of BS carrier animals. Sixty-eight normal homozygous and four heterozygous carrier genotypes were detected and confirmed through traditional PCR-electrophoresis analysis. We concluded that the assay we have developed proved to be a reliable, highly precise and low-cost tool, which could be used to monitor the presence of the BS mutation in uruguayan Holstein breed. [ABSTRACT FROM AUTHOR]

Worldwide use of elite sires has caused inbreeding accumulation and high frequencies of genetic defects in dairy cattle populations. In recent years, several genetic defect genes or haplotypes have been identified in Holstein cattle. A rapid and reliable microfluidic chip with Kompetitive allele‐specific PCR (KASP) assay was developed in our previous study for the detection of heterozygotes at eight genetic defect loci of bovine leukocyte adhesion deficiency (BLAD), Brachyspina syndrome (BS), complex vertebral malformation (CVM), Holstein haplotype 1 (HH1), Holstein haplotype 3 (HH3), Holstein haplotype 4 (HH4), Holstein haplotype 5 (HH5) and haplotype for cholesterol deficiency (HCD). This study aimed to extend that assay to include a newly identified genetic defect of Holstein haplotype 6 (HH6) and to estimate the frequencies of carriers for each of the nine genetic defects in six Chinese Holstein herds. Of the 1633 cows, carrier frequencies of the genetic defects were 6.92%, 5.76%, 4.46%, 4.30%, 3.62%, 2.94%, 1.86% and 0.37% for HH1, HH3, CVM, HH5, HCD, BS, HH6 and BLAD, respectively. No carrier was found for HH4. Notably, 27.43% of cows carried at least one genetic defect, while 2.27% and 0.12% of cows carried double and triple genetic defect alleles, respectively. The existence of genetic defects calls for routine molecular testing and effective management of genetic defects by avoiding carrier‐to‐carrier mating in production herds and eliminating or at least reducing the frequency of the defective alleles through marker‐assisted selection in breeding herds. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the association between teat-end hyperkeratosis (THK) and somatic cell count (SCC) and to assess the effect of SCC on milk yield, fat, and protein percentages of Holstein cows. A total of 740 udder quarters of 185 Holstein cows kept in three commercial herds in Egypt were enrolled in the study from May to September 2019. Foremilk samples were collected from udder quarters for assessing milk SCC, fat, and protein percentages. On the same cows, a digital picture of each teat end orifice was taken with a digital camera. Cows' teats were assessed for THK and classified into two different groups of hyperkeratosis; mild and severe THK. SCC was converted to five classes of somatic cell score (SCS). Simple linear regression was performed to determine the loss of milk yield, fat, and protein percentages. SCC was significantly affected by THK (p<0.0001). About 57% of teats were classified as mild THK and 43% as severe THK. The teats with severe THK recorded higher SCC in milk. It was observed that SCS had a significant effect on fat and protein percentages (p<0.0001). A similar trend was shown for the effect of SCS on milk yield (p<0.05), where the highest values of milk traits were obtained for the lowest SCS. The loss of milk was 220 g/day. Also, fat and protein percentages decreased by 0.11% and 0.08%, respectively, for each unit increase in SCS, from zero to four. In conclusion, severe THK can lead to high SCC, which negatively affects milk traits. [ABSTRACT FROM AUTHOR]

When purchasing animals from abroad, agricultural enterprises often underestimate their demand for feed quality and feeding standards for ensuring genetically determined milk productivity. Therefore, increasing attention should be paid to raising local breeds. During the creation of new production relations, it is very important to preserve achievements of scientists and breeders. The widespread use of red steppe cows is due to good feed payment, unpretentiousness, and their adaptability to the steppe zone with its arid climate. There was a real threat of extinction of purebred red steppe cattle: with the intensification of dairy cattle breeding, as well as low milk productivity, these animals are inferior to the best dairy breeds by productivity, but they are better by endurance, resistance to diseases, and adaptability to extreme environmental conditions. Therefore, scientific research is needed on improving the productive and technological qualities of this breed using the best global gene pool of dairy cattle. This article presents the results of a study on the development of heifers of purebred red steppe cows and their Ayrshire and red-motley Holstein crossbreeds. Differences in the live weight indicators of the purebred and crossbred heifers were due to the effect of crossbreeding and intensive growing technology, which made it possible to maximize the genetic potential of the crossbred animals. [ABSTRACT FROM AUTHOR]

Background and Aim: Milk producers need to ensure that their cows are producing high-quality, nutritional milk, which is influenced by the breed, age, nutrition, and health status of lactating animals. The aim of this study was to determine the effect of animal breed, season, and milk production on the physicochemical characteristics of milk and predicting the effect of these changes on the composition and quality of milk products. Materials and Methods: In total, 80 milk samples (40 Simmental and 40 Holstein) were analyzed from LLP "Kirova" of Pavlodar region (Simmental breed) and JSC "Astana-Onim" of Akmola region (Holstein breed) in the Republic of Kazakhstan. The physicochemical parameters, including fatty acid (FA) content, were studied. Results: The Simmental cows had the lowest mass fraction of fat in the spring at 3.94% and the highest fat content in the winter at 4.09%, which was the overall highest fat content measured in both breeds (P<0.001). The lowest protein in the Simmentals was also measured in the spring. The Holstein cows had the highest fat content at 3.8% and the highest protein content at 3.3% in autumn. Conclusion: It was found that the season and breed significantly affected the physicochemical parameters and the FA contents in cow milk. The superiority of the Simmental cows over the Holstein cows throughout the year was statistically significant. [ABSTRACT FROM AUTHOR]

Milk and dairy products are considered important sources of iodine in several countries. Despite this, there is a paucity of studies that have investigated sources of variation of milk iodine, especially on a large scale. So far, it is not clear if milk iodine content could be increased through breeding in dairy cattle. Recently, a mid-infrared spectroscopy prediction model has been developed for an indirect quantification of iodine content in cow milk, as it is a faster and less expensive method that allows the prediction at population level. The model has coefficient of determination and ratio of performance to deviation in external validation of 0.57 and 1.44, respectively, and it was used in the present study to predict the iodine content from historical milk spectral data to investigate phenotypic and genetic aspects in the Italian Holstein cattle. Based on the accuracy of the model, the prediction was interpreted as proxy for the real milk iodine concentration (IOD P). The data set comprised 33,776 test-day records with IOD P from 4,072 cows. Data of IOD P were transformed through natural logarithm to achieve a normal distribution. The effect of parity, lactation stage, and month of sampling were investigated, and genetic parameters were estimated using a test-day repeatability animal model. Milk IOD P decreased with parities and was the lowest in early lactation. Heritability of IOD P was low (0.025) and it was positively genetically correlated with milk yield and negatively with fat content. Results suggested that it would be challenging to directly improve this trait through breeding strategies in dairy cattle, because IOD P is mainly affected by temporary environmental factors and thus, cannot be easily improved through genetics. Although preliminary, findings of this study suggest that it would be more convenient to develop feeding and management strategies to drive milk iodine level than to put efforts and resources into breeding strategies. Further studies should validate IOD P as an indicator trait of milk iodine content by improving reference data and estimating genetic correlation between predicted and measured values. [ABSTRACT FROM AUTHOR]

Genetic selection of Holstein cattle in the past 2 decades has seen an increased attention to fertility traits. Our hypotheses were that genomic merit for daughter pregnancy rate (GDPR) is positively associated with metabolic responses, hazard of estrus, and estrus characteristics. Pregnant heifers (n = 821) from one herd that were genotyped within 2 mo of birth (Clarifide, Zoetis, Parsippany, NJ) were fitted with automated monitoring devices (SCR Inc., Netanya, Israel) −21 ± 14 d relative to calving. Estrus characteristics recorded from calving to 62 d postpartum were evaluated. Blood samples were collected weekly from a subsample (n = 499) of cows, from 7 to 28 d postpartum, for determination of insulin-like growth factor-1, glucose, and nonesterified fatty acids. Cows received artificial insemination or embryo transfer following detected estrus and those not detected in estrus were submitted to an ovulation synchronization protocol starting at 75 d in milk. Linear and quadratic associations between GDPR and outcomes were analyzed, but when appropriate, results are presented according to GDPR quartile (Q1 = −1.8 to 0.8; Q2 = 0.9 to 1.7; Q3 = 1.8 to 2.5; Q4 = 2.6 to 5.9) based on the parameter estimates of the multivariable models. Genomic merit for daughter pregnancy rate was positively associated with insulin-like growth factor-1 (Q1 = 24.3 ± 0.2; Q2 = 26.8 ± 0.2; Q3 = 28.2 ± 0.2; Q4 = 30.6 ± 0.3 ng/mL) and glucose (Q1 = 67.0 ± 0.1; Q2 = 69.1 ± 0.2; Q3 = 69.6 ± 0.2; Q4 = 70.8 ± 0.2 mg/dL) concentrations, but GDPR was negatively associated with nonesterified fatty acid concentration (Q1 = 281.2 ± 4.9; Q2 = 262.0 ± 5.9; Q3 = 239.3 ± 5.0; Q4 = 221.6 ± 4.7 μmol/L). A positive association was observed between GDPR and hazard of estrus [adjusted hazard ratio and 95% confidence interval = 1.16 (1.06, 1.28)] and number of estrus events (Q1 = 0.50 ± 0.03; Q2 = 0.62 ± 0.04; Q3 = 0.74 ± 0.05; Q4 = 0.86 ± 0.06) within 62 d postpartum, duration of estrus (Q1 = 14.10 ± 0.04; Q2 = 14.48 ± 0.04; Q3 = 14.67 ± 0.04; Q4 = 14.98 ± 0.04 h), probability of activity peak (0 = no estrus, 100 = maximum activity) ≥86 (Q1 = 0.80 ± 0.03; Q2 = 0.83 ± 0.02; Q3 = 0.83 ± 0.03; Q4 = 0.85 ± 0.2), and probability of heat index ≥86 (Q1 = 0.77 ± 0.04; Q2 = 0.81 ± 0.05; Q3 = 0.83 ± 0.03; Q4 = 0.86 ± 0.03). Conversely, GDPR was negatively associated with rumination nadir at estrus (Q1 = −35.5 ± 0.1; Q2 = −37.0 ± 0.1; Q3 = −38.0 ± 0.1; Q4 = −39.6 ± 0.1 min). We detected a positive association between GDPR and hazard of pregnancy (adjusted hazard ratio = 1.11, 95% confidence interval = 1.03, 1.19). Selection for GDPR may improve the hormonal and metabolic status of cows postpartum, leading to earlier resumption of cyclicity, and may improve detection of estrus in commercial herds because it was positively associated with estrus characteristics. [ABSTRACT FROM AUTHOR]

Bovine major histocompatibility complex (MHC) class II region contains many genes. The bovine leukocyte antigen (BoLA)‐DRB3 was reportedly associated with susceptibility of various phenotypes of infections including bovine leukemia virus‐induced lymphoma. However, the association of the remaining genes with various phenotypes has not been clarified due to the complicated genomic structure of the MHC class II region. Thus, in this study, we elucidated the MHC class II genomic structure, including the novel alleles and copy number variations (CNVs). We determined the copy numbers of BOLA‐DQA2 (DQA2), BOLA‐DQB (DQB2), BOLA‐DQA5 (DQA5), BLA‐DQB (DQB1), LOC100848815 (DQA1), and BOLA‐DRB3 (DRB3) in 127 unrelated Holstein cows by TaqMan copy number assay. The genomes were sequenced using target next‐generation sequencing (NGS) based on multiplex polymerase chain reaction. Combining the results of the copy numbers and alleles, we identified the BoLA alleles directly without haplotype estimation. Pairwise linkage disequilibrium (LD) analysis between alleles and genes were performed. The CNVs of DQA2, DQB2, and DQA5 in Holstein cows were detected. The frequency of the whole gene deletion in DQA2, DQB2, and DQA5 was 35.4%, 93.7%, and 93.7%, respectively. After target NGS, we identified 37 alleles in the six genes. Fifteen novel alleles (40.5%) were not registered in the IPD‐MHC Database. LD analysis showed strong LD among the DQB2*deletion, DQA5*deletion, and DRB3*27:03 alleles. Our findings will provide important insights into the identification of the BoLA genes associated with various infection‐related phenotypes. [ABSTRACT FROM AUTHOR]

Two selection goals of inclusion or exclusion of calving interval (CI) in the selection goal function for Holstein cows in Iran, besides milk yield, milk fat percentage, and milk protein percentage, were studied. Four selection indices were composed of using the information on production traits, CI and / or days from calving to first insemination (DFI). The results of the predicted genetic growth in selection goals showed that the index composed of all production and reproduction traits generated the greatest genetic growth. Although CI had a negative coefficient in the selection goal, it is genetic mean increased in any case. However, the magnitude of this undesirable increase was lower in the CI included selection goal. This implies that the inclusion of CI in the selection goal is necessary to control the undesirable growth of this trait. The comparison of indices in this goal reflected that the inclusion of CI along with the production traits resulted in a smaller undesirable change in this trait. Constraining the genetic change in CI in the selection goal impaired the selection efficiency. So, this constraint is not recommended for breeding programs. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of rectal temperature (RT) as well as artificial insemination (AI) technique on pregnancy rates in Holstein cows and artificial insemination or embryo transfer (ET) techniques in Holstein heifers during summer. The experiments were conducted on five dairy farms in Hungary, where 1 631 data were examined. The RT was measured immediately before reproductive techniques using a digital thermometer. The effects of animal group and month on RT were analysed. The enhancement of RT until September can be seen in heifers, but the highest RT of cows occurred during July. In line with the enhancement of RT the pregnancy rate decreased in all groups; the lowest (cows) and the highest (heifers) value was observed in July. Moderate to high negative coefficients of correlation were detected between rectal temperature and pregnancy rate for particular groups (r = -0.3 - -0.7). More than 92% of ET, 48% and 16% of inseminated heifers and cows were pregnant up to the category of 39.1 °C of RT, above this it did not change considerably in the inseminated groups. In inseminated animals with RT higher than 39.1 °C significantly higher services per conception could be observed contrary to ET heifers. ET may become a more effective strategy to improve pregnancy success in heifers compared to AI during summer. [ABSTRACT FROM AUTHOR]