Project description:The aim of this study was to identify genomic regions associated with 305-day milk yield and lactation curve parameters on primiparous (n = 9,910) and multiparous (n = 11,158) Holstein cows. The SNP solutions were estimated using a weighted single-step genomic BLUP approach and imputed high-density panel (777k) genotypes. The proportion of genetic variance explained by windows of 50 consecutive SNP (with an average of 165 Kb) was calculated, and regions that accounted for more than 0.50% of the variance were used to search for candidate genes. Estimated heritabilities were 0.37, 0.34, 0.17, 0.12, 0.30 and 0.19, respectively, for 305-day milk yield, peak yield, peak time, ramp, scale and decay for primiparous cows. Genetic correlations of 305-day milk yield with peak yield, peak time, ramp, scale and decay in primiparous cows were 0.99, 0.63, 0.20, 0.97 and -0.52, respectively. The results identified three windows on BTA14 associated with 305-day milk yield and the parameters of lactation curve in primi- and multiparous cows. Previously proposed candidate genes for milk yield supported by this work include GRINA, CYHR1, FOXH1, TONSL, PPP1R16A, ARHGAP39, MAF1, OPLAH and MROH1, whereas newly identified candidate genes are MIR2308, ZNF7, ZNF34, SLURP1, MAFA and KIFC2 (BTA14). The protein lipidation biological process term, which plays a key role in controlling protein localization and function, was identified as the most important term enriched by the identified genes.
Project description:Milk is a highly nutritious natural product that provides not only a rich source of amino acids to the consumer but also hundreds of bioactive peptides and proteins known to elicit health-benefitting activities. We investigated the milk protein profile produced by Holstein and Jersey dairy cows maintained under the same diet, management and environmental conditions using proteomic approaches that optimize protein extraction and characterization of the low abundance proteins within the skim milk fraction of bovine milk. In total, 935 low abundance proteins were identified. Gene ontology classified all proteins identified into various cellular localization and function categories. A total of 43 low abundance proteins were differentially expressed between the two dairy breeds. Bioactive proteins involved in host-defense, including lactotransferrin (P=0.0026) and complement C2 protein (P=0.0001), were differentially expressed by the two breeds, whereas others such as osteopontin (P=0.1788) and lactoperoxidase (P=0.2973) were not. This work is the first to outline the protein profile produced by two important breeds of dairy cattle maintained under the same diet, environment and management conditions in order to observe likely true breed differences. This research now allows us to better understand and contrast further research examining the bovine proteome that includes these different breeds.Biological significanceWithin the last decade, the amount of research characterizing the bovine milk proteome has increased due to growing interest in the bioactive proteins that are present in milk. Proteomic analysis of low abundance whey proteins has mainly focused on human breast milk; however, previous research has highlighted the presence of bioactive proteins in bovine milk. Recent publications outlining the cross-reactivity of bovine bioactive proteins on human biological function highlight the need for further investigation into the bovine milk proteome. The rationale behind this study is to characterize and compare the low abundance protein profile in the skim milk fraction produced from Holstein and Jersey breeds of dairy cattle, which are two major dairy cattle breeds in the USA. A combination of fractionation strategies was used to efficiently enrich the low abundance proteins from bovine skim milk for proteomic profiling. A total of 935 low abundance proteins were identified and compared between the two bovine breeds. The results from this study provide insight into breed differences and similarities in the milk proteome profile produced by two breeds of dairy cattle.
Project description:Recently, Jersey cattle was introduced and produced by embryo transfer to Korea. This study was conducted to investigate the differences of milk compositions between Jersey and Holstein cows and the relationship between days in milk (DIM) and milk compositions during early lactation. Data were collected from twelve lactating cows from Department of Animal Resources Development at National Institute of Animal Science. Cows in parity 1 were used, and calved at spring from April to March of 2017. All cows were housed in two sections within a free-stall barn, which divided into six from each breed, and received a basal total mixed ration. Milk samples of each cow were collected at 3 DIM and 30 DIM for analyzing the milk compositions, including fatty acids (FA), amino acids and minerals. Total solids, citrate, and milk urea nitrogen level were differed between the breeds (p < 0.05). As DIM went from 3 to 30, milk protein, total solids, and somatic cell count decreased (p < 0.05), but lactose increased in all breed milk (p < 0.05). Citrate and free fatty acid (FFA) elevated in Jersey milk (p < 0.05), whereas reduced in Holstein milk (p < 0.05). Proportions of some individual FA varied from the breeds. Myristic (C14:0), palmitic (C16:0), and arachidonic acid (C20:4) in milk from all cows were higher at 3 DIM than at 30 DIM (p < 0.05). Also, stearic (C18:0) and oleic acid (C18:1) were lower at 3 DIM than at 30 DIM (p < 0.05), and the C18:1 to C18:0 ratio was significantly differed in DIM × breed interactions (p < 0.05). The contents of the individual amino acids did not differ from the breeds. Calcium, phosphorous, magnesium, and zinc (Zn) contents was significantly increased in Holstein milk than Jersey milk at 3 DIM. Also, K and Zn concentrations were higher in Holstein milk than in Jersey milk at 30 DIM (p < 0.05). It was concluded that Jersey cows would produce more effective milk in processing dairy products and more proper energy status compared with Holstein cows in early lactation under the same environmental and nutritional conditions.
Project description:The aim was to estimate genetic parameters for milk urea (MU) concentration and its relationship with milk yield and compositions in Holstein dairy Cows. Edited data were 90,594 test-day records of milk yield and composition collected during 2015 to 2018 on 13,737 lactations obtained from 7,850 Holstein cows in 50 herds. Random regression test-day model was used to estimate genetic parameters. (Co)variance components were estimated with the Bayesian Gibbs sampling method using a single chain of 400,000 iterates. The first 50,000 iterates of each chain were regarded as a burn-in period. Mean (SD) of MU was 23.03 (5.99) and 22.41 (5.74) mg/dl in primiparous and multiparous cows, respectively. Average heritability estimates for daily MU was 0.33 (SD = 0.02) ranged 0.29 to 0.36 and 0.32 (SD = 0.03) ranged 0.27 to 0.34, respectively, for primiparous and multiparous cows. The mean (SD) genetic correlation between MU and milk yield, fat yield, protein yield, lactose yield, fat percentage, protein percentage, lactose percentage, and somatic cell score was, respectively, -0.02 (0.03), -0.02 (0.01), 0.01 (0.04), 0.01 (0.03), 0.00 (0.07), -0.03 (0.04), 0.00 (0.01), -0.11 (0.06) in primiparous cows. The corresponding values in multiparous cows were -0.01 (0.02), -0.01 (0.03), -0.04 (0.04), -0.04 (0.04), 0.04 (0.04), 0.04 (0.07), -0.03 (0.09), 0.06 (0.11), respectively. The results indicate that selection on MU is possible with no effect on milk yield or compositions, however, relationships between MU and other important traits such as longevity, metabolic diseases, and fertility are needed.
Project description:Bovine milk is known to contain naturally occurring peptides, but relatively few of their sequences have been determined. Human milk contains hundreds of endogenous peptides, and the ensemble has been documented for antimicrobial actions. Naturally occurring peptides from bovine milk were sequenced and compared with human milk peptides. Bovine milk samples from six cows in second-stage peak lactation at 78-121 days postpartum revealed 159 peptides. Most peptides (73%) were found in all six cows sampled, demonstrating the similarity of the intramammary peptide degradation across these cows. One peptide sequence, ALPIIQKLEPQIA from bovine perilipin 2, was identical to another found in human milk. Most peptides derived from ?-casein, ?s1-casein, and ?s2-casein. No peptides derived from abundant bovine milk proteins such as lactoferrin, ?-lactoglobulin, and secretory immunoglobulin A. The enzymatic cleavage analysis revealed that milk proteins were degraded by plasmin, cathepsins B and D, and elastase in all samples.
Project description:Our objective was to characterize the protein coding portion of the bovine mammary gland transcriptome by magnitude of RNA-seq read counts. EBseq analysis determined no differentially expressed genes due to postruminal lysine infusion, therefore, read counts were averaged across treatment and block. DAVID functional annotation analysis was utilized to determine specific gene ontologies and KEGG pathways to describe the data by magnitude of reads.
Project description:We tested for a forage allowance effect on the milk yield of early lactation dairy cow herds grazing swards sown with perennial ryegrass (Lolium perenne L.), white clover (Trifolium repens L.) and plantain (Plantago lanceolata L.) relative to perennial ryegrass alone. The examined allowances consisted of offering 12, 14, 16, 18, 20 or 25 kg of dry matter (DM)/cow per day of grazeable herbage, with diverse swards sown as mixtures and spatially adjacent monocultures. After adapting cows to their assigned forage type for 8 days, treatment effects on milk yield and composition, blood metabolites (beta-hydroxybutyrate, non-esterified fatty acids and urea concentrations), body weight change, forage intake and selection differentials for forage species and certain nutrients were monitored over 7 days. We confirmed a forage allowance effect on milk yield improvements in dairy cows grazing diverse swards relative to perennial ryegrass monocultures. Improvements in milk yield were evident at forage allowances of 14 to 20 kg of DM/cow per day, diminishing at the highest allowance of 25 kg of DM/cow per day. Improvements in milk yield for the mixture and spatially adjacent monocultures peaked at forage allowances of 18 and 16 kg of DM/cow per day, equalling increases of 1.3 and 1.2 kg of milk/cow per day, respectively.
Project description:BackgroundEven if breed, parity, dietary and environmental management are same, dairy cows still have notable differences in milk yield that may be underpinned by physiologic differences.ObjectivesThis study aimed to investigate the physiological dissimilarities of dairy cows with different milk yields.MethodsThirty cows were sorted into high milk-yielding cows (group H: 58.93±2.31 kg/day), moderate milk-yielding cows (group M: 44.99±0.54 kg/day), and low milk-yielding cows (group L: 24.99±6.83 kg/day) according to milk yield. Blood was collected and serum parameters were assessed. Rumen fluid was collected for the evaluation of rumen fermentation parameters (RFPs) and bacterial community composition (BCC).ResultsSerum prolactin, growth hormone, glutathione peroxidase, immunoglobulin A and non-esterified fatty acid had a significantly positive correlation with milk yield (p < 0.05), whereas serum glucagon and total antioxidant capacity had a significantly negative correlation with milk yield (p < 0.05). The concentration of valeric acid and the ratio of acetic acid to propionic acid in the rumen fluid in group H was significantly lower than that in group L (p < 0.05). The concentration of acetic acid and butyric acid in group H was significantly lower than that in groups M and L (p < 0.05). The relative abundances of Ruminococcaceae_NK4A214_group, Prevotella_1, Rikenellaceae_RC9_gut_group, Christensenellaceae_R-7_group, Muribaculaceae, and Ruminococcus_2 were negatively correlated with milk yield, whereas the relative abundance of Succinivibrionaceae_UCG-001, Lachnospiraceae_NK3A20_group, Shuttleworthia and Dialister were positively correlated with milk yield (p < 0.05).ConclusionsThis study indicates that dairy cows with different milk yields have clear divergence in serum indicators, RFPs, BCC and rumen microbial metabolism.
Project description:Parturition and lactation stress greatly affect physiological and metabolic status of postpartum cows. Monitoring feeding behavior can help assess the health status of postpartum cows. This study aimed to explore the changes in feeding behavior, milk yield (MY), serum indexes, and metabolites of dairy cows during three weeks postpartum. Furthermore, the relationships between feeding behavior, milk yield and serum metabolites were investigated. One hundred seventy-eight healthy multiparous Holstein dairy cows were enrolled to continuously record feeding behavior variables, including feeding time (FT), frequency of feeding (FF), and average feeding time (AFT), using the Nedap neck collar devices, wherein the milk yield was recorded. Out of 178 Holstein dairy cows, 20 cows with the same parity number (2 parities), body condition score (3.0 ± 0.25, recorded in 7 days before parturition), and with eutocic calvings, were selected to explore the serum indexes changes on week 1, 2, and 3 postpartum. Then, 7 cows were further selected based on similar calving date (± 7 d) for metabolic transition detection. Compared to week 1 postpartum, the FT and AFT normalized values on week 2 and 3 postpartum were significantly increased (P < 0.001). The normalized values of FT and AFT were significantly and positively correlated with MY (P < 0.01). Furthermore, the serum total protein (TP), total cholesterol (T-Chol) and IgA contents on week 2 and 3 postpartum were significantly increased compared to week 1 postpartum, while the β-hydroxybutyric acid (BHBA) concentration was significantly decreased. Serum malondialdehyde (MDA), interleukin-6 (IL-6), and leptin (LEP) contents of the 2nd week postpartum, were significantly declined compared to the 1st week postpartum. The normalized values of FT was negatively correlated with serum BHBA level, while positively correlated with the contents of TP and T-Chol (P < 0.05). According to UPLC-MS/MS and pathway analysis results, the serum levels of glycerophospholipids changed most in first three weeks postpartum, which were mainly related to glycerophospholipid metabolism. Finally, the correlation analysis showed that 29 glycerophospholipids (GPs) and 3 fatty acyls (FAs) were significantly and positively correlated with the FT and AFT normalized values (P < 0.05). Together, the findings suggest that the feeding behavior variables, such as FT and AFT, could serve as reliable indicators of energy metabolism in dairy cows during the first three weeks postpartum.
Project description:Residual feed intake (RFI) is an efficiency trait underpinning profitability and environmental sustainability in dairy production. This study compared performance during a complete lactation of 36 multiparous dairy cows divided into three equal-sized groups with high (HRFI), intermediate (IRFI) or low RFI (LRFI). Residual feed intake was determined by two different equations. Residual feed intake according to the NorFor system was calculated as (RFINorFor) = (NEintake)-(NEmaintenance + NEgestation + NEmilk-NEmobilisation + NEdeposition). Residual feed intake according to the USA National Research Council (NRC) (RFINRC) was calculated as: RFI = DMI - predicted DMI where predicteds DMI = [(0.372× ECM)+(0.0968×BW0.75)]×(1-e-0.192×(DIM/7+3.67)). Cows in the HRFINorFor group showed higher daily CH4 production, CH4/ECM and CH4 yield (g/kg DMI) than IRFINorFor and LRFINorFor cows. Cows characterized by high efficiency (LRFINorFor) according to the NorFor system had lower body weight. Dry matter intake and apparent dry matter digestibility were not affected by efficiency group but milk yield was lower in the low efficiency, HRFINorFor, group. Cows characterized by high efficiency according to the NRC system (LRFINRC) had lower dry matter intake while yield of CH4 was higher. Daily CH4 production and CH4 g/kg ECM did not differ between RFINRC groups. Dairy cows characterized by high efficiency (both LRFINorFor and LRFINRC cows) over a complete lactation mobilized more of their body reserves in early lactation as well as during the complete lactation. The results also indicated great phenotypic variation in RFI between different stages the lactation.