Milk Fat Percentage Research Articles

Transcriptomic and Metabolomics Joint Analyses Reveal the Influence of Gene and Metabolite Expression in Blood on the Lactation Performance of Dual-Purpose Cattle (Bos taurus)

Blood is an important component for maintaining animal lives and synthesizing sugars, lipids, and proteins in organs. Revealing the relationship between genes and metabolite expression and milk somatic cell count (SCC), milk fat percentage, milk protein percentage, and lactose percentage in blood is helpful for understanding the molecular regulation mechanism of milk formation. Therefore, we separated the buffy coat and plasma from the blood of Xinjiang Brown cattle (XJBC) and Chinese Simmental cattle (CSC), which exhibit high and low SCC/milk fat percentage/milk protein percentage/lactose percentages, respectively. The expression of genes in blood and the metabolites in plasma was detected via RNA-Seq and LC-MS/MS, respectively. Based on the weighted gene coexpression network analysis (WGCNA) and functional enrichment analysis of differentially expressed genes (DEGs), we further found that the expression of genes in the blood mainly affected the SCC and milk fat percentage. Immune or inflammatory-response-related pathways were involved in the regulation of SCC, milk fat percentage, milk protein percentage, and lactose percentage. The joint analysis of the metabolome and transcriptome further indicated that, in blood, the metabolism pathways of purine, glutathione, glycerophospholipid, glycine, arginine, and proline are also associated with SCC, while lipid metabolism and amino-acid-related metabolism pathways are associated with milk fat percentage and milk protein percentage, respectively. Finally, related SCC, milk fat percentage, and milk protein percentage DEGs and DEMs were mainly identified in the blood.

Milk production and composition in warm-climate regions: a systematic review and meta-analysis.

Milk production is a key component of the agriculture sector in the tropics and subtropics, contributing 47.32% to global milk production. This study aimed to quantify milk production and composition (fat and protein) in warm-climate regions located between 30 degrees north and south of the equator. A meta-analysis was conducted using the standardized mean (SM) for milk production, fat percentage, and protein percentage, all adjusted for dry matter intake (DMI), focusing on lactating ruminants. A total of 42, 11, 15, and 16 research papers were selected for cows, buffalo, sheep, and goats, respectively, encompassing 2421 animal records from experiments published between 1992 and 2024. The SM for milk production was 10.38, 9.77, 0.79, and 1.13kg/day/animal for cows, buffalo, sheep, and goats, respectively. Due to the significant variance between different cow breeds, the study divided the cows into three main groups based on breed type crossbreds, foreign, and local breeds. The SM for milk production per animal was 11.49kg/day for crossbreds, 22.95kg/day for foreign breeds, and 7.13kg/day for local breeds. The effect of DMI on the SM of milk production for cows, sheep, and goats was highly significant. For milk fat, the SM was 3.95, 6.64, 4.70, and 3.56% for cows, buffalo, sheep, and goats, respectively. Regarding milk protein, the SM was 3.36, 3.91, 4.34, and 3.45% for cows, buffalo, sheep, and goats, respectively. The results of this meta-analysis highlight that warm-climate regions are significant contributors to global dairy production. Furthermore, improving ruminant milk production and quality in hot climates need further efforts.

Metabolomics Reveals the Mechanism by Which Sodium Butyrate Promotes the Liver Pentose Phosphate Pathway and Fatty Acid Synthesis in Lactating Goats

This study aimed to explore the effects of sodium butyrate on liver metabolism in goats subjected to a high-concentrate diet. We randomly assigned twelve Saanen-lactating goats into two groups, one of which received a high-concentrate diet (concentrate: forage = 60:40, control group), while the other received the same basal diet supplemented with sodium butyrate (SB) (10 g/kg basal diet, SB group). Compared with the control diet, the SB diet considerably increased the milk fat percentage and content (p < 0.05), with an increase of 0.67% in the milk fat content of the SB group. By employing a global metabolomics approach based on ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS), we identified 6748 ions in ESI+ mode and 3573 ions in ESI− mode after liver isolation from both groups. A total of twenty-three metabolites, including phospholipids, fatty acids, and ribose phosphate, were found to be dysregulated according to a search against the human metabolome database (HMDB). Pathway analysis revealed activation of the pentose phosphate pathway, glycerophospholipid metabolism, and unsaturated fatty acid synthesis. The SB diet also modulated the expression of key lipogenic enzymes, such as acetyl-CoA carboxylase (ACC) and stearoyl-CoA desaturase (SCD-1), which are downstream targets of the transcription factor sterol regulatory element-binding proteins-1c (SREBP-1c), inducing a significant upregulation (p < 0.05). Furthermore, 6-phosphogluconate dehydrogenase (6PGDH) levels in the liver were elevated after the lactating goats were fed the SB diet (p < 0.05). Our study reveals that the SB diet may offer substantial benefits in enhancing the milk quality of subacute ruminal acidosis (SARA) goats. This is accomplished by augmenting the activity of the liver pentose phosphate pathway and the process of de novo fatty acid synthesis in lactating goats.

Host genetic regulation of specific functional groups in the rumen microbiome of dairy cows: Implications for lactation trait

IntroductionRuminants play a pivotal role in our society by transforming non-consumable substances from industrial by-products and plant fibers into valuable resources such as meat and milk. This remarkable conversion ability is primarily attributed to the rumen microbiota, which is influenced by various factors, including diet, climate, and geographical location. In recent years, increasing research has shown that host factors (breed, genetic variation, etc.) also play vital roles in shaping rumen microbial composition and function in cattle. ObjectiveThis study aims to provide a theoretical basis and an opportunity for further investigating the regulation of lactation traits in dairy cows through host genetics and the interaction with the rumen microbiota. MethodTo investigate the interactions between host genotype, rumen microbiota, and animal phenotype, we curated and analyzed the dairy herd improvement (DHI) data, single nucleotide polymorphisms (SNPs) genotypes, and 16S rumen microbiota data from 1,169 Holstein dairy cows. Heritability and microbiability estimation, along with genome-wide association studies (GWAS) were performed to identify candidate microorganisms and host genetic loci. ResultWe identified thirty-one heritable taxa, whose functions were predominantly enriched in carbohydrate metabolism and energy metabolism. The genome-wide association study revealed that nine heritable bacteria were significantly associated with forty-three SNPs. Functional genes located within or near these SNPs were primarily associated with rumen epithelial development. Additionally, these nine heritable bacteria were primarily annotated as complex polysaccharide degraders and butyrate producers, such as Fibrobacter sp900143055 and Pseudoruminococcus massiliensis, which showed significant associations with milk yield and milk fat percentage. Compared to previous studies, we newly discovered the existence of a high heritability of Olsenella umbonate, Butyrivibrio hungatei, among others.

GDF15 knockout does not substantially impact perinatal body weight or neonatal outcomes in mice.

Growth differentiation factor-15 (GDF15) increases in circulation during pregnancy and has been implicated in food intake, weight loss, complications of pregnancy, and metabolic illness. We used a Gdf15 knockout mouse model (Gdf15-/-) to assess the role of GDF15 in body weight regulation and food intake during pregnancy. We found that Gdf15-/- dams consumed a similar amount of food and gained comparable weight during the course of pregnancy compared to Gdf15+/+ dams. Insulin sensitivity on gestational day 16.5 was also similar between genotypes. In the postnatal period, litter size, and survival rates were similar between genotypes. There was a modest reduction in birth weight of Gdf15-/- pups, but this difference was no longer evident postnatal day 3.5 to 14.5. We observed no detectable differences in milk volume production or milk fat percentage. These data suggest that GDF15 is dispensable for changes in food intake, and body weight as well as insulin sensitivity during pregnancy in a mouse model.

Effects of Oregano on Lactation Performance, Nutrient Digestibility, Ruminal Fermentation Parameters, and Methane Emissions in Dairy Cows: A Meta-Analysis

Growing concerns regarding antibiotic use in livestock, due to antibiotic resistance and potential human transmission, have led to increased interest in herbs and their derivatives, including essential oils, which possess antimicrobial properties that may enhance overall productivity and serve as a strategy for methane mitigation. The objective of this meta-analysis was to investigate the effects of adding oregano to the diet in different forms (essential oils, plant materials, or leaves) on the dry matter intake (DMI), milk yield (MY), milk components, nutrient digestibility, ruminal fermentation parameters, and methane (CH4) emissions of dairy cows. A literature search was conducted to identify papers published from 2000 to 2023. Effect size for all outcomes was reported as a standardized means difference (SMD) and raw means difference with 95% confidence intervals. Heterogeneity was determined using the Q test and I2 statistic. The results of the meta-analysis indicated that adding oregano had no effect on DMI (SMD = 0.081; p = 0.507) and MY (SMD = 0.060; p = 0.665). Milk fat percentage, milk protein percentage, and milk lactose percentage were not affected by oregano. The addition of oregano to the diet significantly decreased dry matter digestibility (SMD = −0.502; p = 0.013), crude protein digestibility (SMD = −0.374; p = 0.040), and neutral detergent fiber digestibility (SMD = −0.505; p = 0.014). Ruminal pH (SMD = −0.122; p = 0.411), total volatile fatty acids concentration (SMD = −0.038; p = 0.798), acetate (SMD = −0.046; p = 0.757), propionate (SMD = 0.007; p = 0.960), and butyrate (SMD = 0.037; p = 0.801) proportion were not affected by oregano. The addition of oregano to the diet tended to decrease CH4/DMI (SMD = −0.275; p = 0.095) but did not affect CH4 production (SMD = −0.156; p = 0.282). Heterogeneity (Q and I2) was non-significant for all parameters. We conclude that the inclusion of oregano in various forms (essential oils, plant materials, or leaves) in the diet of dairy cows reduces nutrient digestibility but does not significantly affect DMI, MY, milk components, ruminal fermentation parameters, or CH4 production. Future research should focus on optimizing the dosage of oregano (both EOs and plant materials) and exploring the impact of its form on lactation, nutrient digestibility, ruminal fermentation, and CH4 emissions in dairy cows.

Effect of a Bacillus subtilis-based direct-fed microbial, on milk yield, milk components, feed intake and plasma hormones and metabolites in lactating Holstein cows

To investigate the effects of a Bacillus-based direct-fed microbial on milk production and related factors, a study was conducted on Holstein cows (n = 28) starting at 90 ± 11 DIM. The cows were divided into two dietary groups: a control group (CON) that received a total mixed ration (TMR), and a Bacillus-fed group (DFM) that received the same TMR along with a Bacillus subtilis product containing two strains (747 and 1781) in equal amounts. The study lasted for 25 wk and included both primiparous and multiparous cows. The cows were housed in a free-stall barn and were provided with ad libitum TMR, which was fed twice a day. Their daily meals and dry matter intake (DMI) were recorded during wk 1–4 and wk 19–25 using electronic feeders. Milk samples were collected weekly during morning and evening milkings and analyzed for milk fat, protein, lactose, and milk urea nitrogen (MUN). Blood samples were also collected weekly and analyzed for plasma glucose, insulin, cholesterol, insulin-like growth factor 1 (IGF1), and progesterone concentrations. Additionally, rumen fluid samples were collected and evaluated for various species of bacteria. One of the key findings was that daily 4 % fat-corrected milk production (FCM) was influenced by the interaction between treatment (DFM vs. CON) and parity (primiparous vs. multiparous), with multiparous DFM cows producing 11 % more FCM compared to CON. The DFM cows also had a higher milk fat percentage (4.41 % vs. 4.02 %) and MUN concentrations were 1.0 mg/dL higher in the DFM group. In terms of blood metabolites and hormones, multiparous DFM cows had lower plasma cholesterol, glucose, and insulin concentrations compared to CON multiparous cows. However, there were no significant differences between the groups in terms of plasma IGF1 concentrations, insulin-to-glucose ratios, and luteal phase plasma progesterone concentrations. The analysis of rumen fluid samples revealed that the abundance of Ruminococcus albus and Fibrobacter succinogenes group I was greater in the DFM cows compared to CON cows. Furthermore, during the periods when feed intake was measured, the DFM cows had a 9 % reduction in feed intake and a 14 % improvement in feed efficiency (FCM per DMI) compared to CON cows. In conclusion, the two-strain Bacillus product used in this study (Certillus) showed potential as an effective direct-fed microbial. It was found to increase feed efficiency and milk production by altering the composition of ruminal microbiota and metabolism in the cows.

Effects of pre- and postpartum dietary fat sources (soybean oil versus linseed oil) on lactation performance and blood metabolites in transition dairy cows

This study investigated the effects of supplementation with two calcium salt fatty acid sources (soybean oil (CaSO) and linseed oil (CaLN)) before and after parturition on lactation performance and blood metabolite profiles in dairy cows. A study was conducted with twenty-four multiparous Holstein cows (parity = 3.12 ± 0.9 and Backfat thickness = 21.77 ± 1.98) that were divided into a 2 × 2 factorial design 21 days before expected calving. The aim was to investigate the interplay between prepartum (CaSO or CaLN, at 2 % of dry matter) and postpartum (at 1.4 % of dry matter) fat supplementation on lactation performance and blood metabolite profiles. Initially, cows were grouped according to the source of prepartum fat (either CaSO or CaLN, with 12 cows in each group). Postpartum, these groups were further subdivided according to whether the fat source was administered continuously (LN-LN, SO-SO) or alternately (LN-SO, SO-LN) over a 28-day period. This resulted in four different treatment groups, each with six cows. The fat supplements contained 84 % fat and 9 % Ca. No statistically significant differences were found in dry matter intake (DMI), colostrum yield or most concentrations of blood metabolites (insulin, cholesterol, glucose, triglycerides, total protein, albumin, β-hydroxybutyric acid (BHB), non-esterified fatty acids (NEFA), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and urea-N). However, cows fed CaSO prepartum had a significantly higher plasma concentration of insulin-like growth factor-1 (IGF-1) than cows fed CaLN. Cows fed CaSO had higher backfat thickness (BFT) from day −21–0 than those fed CaLN (P = 0.05). Notably, cows in the SO-SO group lost the most weight, while cows in the SO-LN group lost the least, especially on days 21 and 28 postpartum (P = 0.05). Switching from soybean oil prepartum to linseed oil postpartum (SO-LN) significantly increased milk production in the first 28 days of lactation compared to other diets. In addition, the fat content in milk was influenced by the type of fat supplementation prepartum, with cows receiving CaSO having a lower milk fat percentage than those receiving CaLN (P < 0.05). The results on blood parameters suggest potential benefits of the SO-LN diet for postpartum cows, as emphasized by stable BHB concentrations and the highest IGF-1 concentrations, especially without the elevated BHB concentrations typically associated with the SO-SO diet. The blood concentrations of total protein, urea-N, triglycerides and NEFA were not affected by the treatments. Also, the dietary change did not adversely affect liver function, as shown by unchanged AST and ALT concentrations. Therefore, the results suggest that a dietary intervention involving the administration of soybean oil prepartum and switching to linseed oil postpartum (SO-LN strategy) has the potential to improve milk yield during the early lactation period.

Effect of feeding two types of concentrates in morning and evening meals and two types of fat supplement on diurnal patterns of plasma parameters in lactation dairy cows

The diurnal patterns of feed intake and TMR composition influence blood parameters in dairy cows; however, the effect of feeding TMR with different compositions in the morning and evening meals is not well characterized. In a completely random design, forty Holstein cows (110 ± 30 days postpartum) were randomly assigned to four treatment groups, with 10 cows per treatment. The treatments were as follows: a base diet containing 50 % cereal starch from barley grain and 50 % cereal starch from corn grain in the morning and evening meal + either prilled fatty acids supplement (EqP) or calcium salts of fatty acids supplement (EqCS); a base diet containing 25 % cereal starch from barley grain, 75 % cereal starch from corn grain in the morning meal, and 75 % cereal starch from barley grain and 25 % cereal starch from corn grain in the evening meal + either prilled fatty acids supplement (DiP) or calcium salts of fatty acids supplement (DiCS). Dry matter intake was affected by treatments (P ˂ 0.01). The highest intake was observed for EqP, EqCS, DiP,and DiCS. 3.5 % fat-corrected milk and milk fat percentage was significantly higher for EqP than other treatments (P ˂ 0.01), but other milk components were not significantly different among treatments (P ˃ 0.05). A significant difference was observed for glucose, cholesterol, TG, AST, and insulin concentration among treatments (P ˂ 0.01). The concentrations of all plasma parameters (glucose, cholesterol, TG, BUN, AST, insulin, and NEFA) significantly changed over 24-h period (P ˂ 0.01). Plasma concentrations of glucose, cholesterol, TG, BUN, AST, insulin, and NEFA displayed a treatment-by-time interaction (P ˂ 0.01). In general, changes in the cereal starch ratio (corn and barley) in TMR in each meal during a day affect the 24-h concentration of plasma parameters, but there was no strong evidence of leverage for cows’ metabolism.

A comprehensive analysis of the effects of DGAT1 K232A polymorphism on milk production and fertility traits in Holstein Friesian and Jersey cows reared in Türkiye

Abstract. Research on the diacylglycerol acyltransferase 1 (DGAT1) K232A marker in cattle shows inconsistent results across regions, largely due to small sample sizes, limited genetic variation, and data restricted to few lactations, which complicates establishing a reliable genotype–phenotype correlation. This research aimed to determine the effect of the K232A polymorphism of the bovine DGAT1 gene on milk production and quality traits in dairy cattle. We used 1104 cattle, including 828 Holstein Friesian and 276 Jersey cows. The analysis utilized extensive data from six lactations of cows raised on four commercial dairy farms. We genotyped the population using the polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) technique and Sanger sequencing for verification. We then evaluated the 305 d and test-day milk yields as well as fat and protein yields and percentages. The number of inseminations per conception and calving ease were also assessed as reproduction indices. Genotype–phenotype associations were quantified using linear mixed models. The AA genotype was absent in Jersey cows, and the heterozygous genotype was predominant in both breeds. The K232A marker was significantly associated with test-day milk yield, fat, and protein content in Jersey cows. Further, it substantially affected the fat percentage of milk in Holstein Friesian cows (p&lt;0.001). We found that the KK genotype is highly desirable for milk quality and especially fat content. This comprehensive assessment demonstrated that the KK genotype of the DGAT1 K232A polymorphism significantly influenced fat and protein contents in dairy cattle.

DeepGenomeScan of 15 Worldwide Bovine Populations Detects Spatially Varying Positive Selection Signals.

Identifying genomic regions under selection is essential for understanding the genetic mechanisms driving species evolution and adaptation. Traditional methods often fall short in detecting complex, spatially varying selection signals. Recent advances in deep learning, however, present promising new approaches for uncovering subtle selection signals that traditional methods might miss. In this study, we utilized the deep learning framework DeepGenomeScan to detect spatially varying selection signatures across 15 bovine populations worldwide. Our analysis uncovered novel insights into selective sweep hotspots within the bovine genome, revealing key genes associated with physiological and adaptive traits that were previously undetected. We identified significant quantitative trait loci linked to milk protein and fat percentages. By comparing the selection signatures identified in this study with those reported in the Bovine Genome Variation Database, we discovered 38 novel genes under selection that were not identified through traditional methods. These genes are primarily associated with milk and meat yield and quality. Our findings enhance our understanding of spatially varying selection's impact on bovine genomic diversity, laying a foundation for future research in genetic improvement and conservation. This is the first deep learning-based study of selection signatures in cattle, offering new insights for evolutionary and livestock genomics research.

PSXI-30 Economic impact of pre-training on dairy cattle automatic milking system acclimation

Abstract Pre-training in automatic milking systems (AMS) has the potential to increase milk production and milk quality. In a recent study, cows that experienced pre-training (TRT; i.e. intentional training access with an AMS prior to first AMS milking) had greater milk yield and fat percentages compared with no pre-training (38.4 vs. 37.6 ± 0.2 kg/d; 4.75 vs. 4.38 ± 0.06%; P &amp;lt; 0.01, and &amp;lt; 0.01 respectively). Similarly, cows without pre-training had greater somatic cell count (SCC; 298,860 vs. 188,220 ± 10,700 cells/mL; P &amp;lt; 0.001). The time required for pre-training could be a limiting factor (40 ± 10 h/wk), and the economic implications of labor versus long-term benefits must be examined. To that end, a stochastic simulation tool was developed to consider the increased costs of labor and the potential benefits of improved milk yield, milk fat percentage, and decreased somatic cell count. The GRKS distribution with minimum, mean, and maximum values was used to model increases in milk yield (0, 1.4, 1.8 kg), fat percentage (0, 3.5%, 4.5%), and labor cost ($0.0011, $0.0016, $0.0020 per h) and decreases in SCC (0, 120, 130 x 103 cells/mL) per hundredweight of milk produced. Baseline values for milk production ranged from 14.7 to 59.2 kg/cow/d in 4.4 kg increments with fat percentage of 3.5% and SCC of 312,000 cells/mL. The model assumed a minimum increase across milk yield, fat, and SCC of 0 (no change). The Simetar add-on in Microsoft Excel simulated 500 iterations across three herd size scenarios (60, 120, and 480 cows) and calculated the marginal return on investment across a 90-d period for all milk production ranges. Regardless of starting milk production level, pre-training had a positive economic impact across all levels (30 to 50 h) and herd sizes (Table 1). Financial impact per cow per d with input of 30, 40, and 50 h ranged from $0.58 to $0.73, $0.56 to $0.71, and $0.54 to $0.70. The majority of simulations returned a positive marginal impact for pre-training. If pre-training resulted in a loss, it ranged from $242 to $1,937, $323 to $2,585, $405 to $3,246, across 30, 40, and 50 hours, respectively. Based on these results, the investment in pre-training time was consistently beneficial for simulated herds.

Effect of Exogenous Melatonin on Performance and Mastitis in Dairy Cows.

Mastitis is an important factor affecting the health of cows that leads to elevated somatic cell counts in milk, which can seriously affect milk quality and result in huge economic losses for the livestock industry. Therefore, the aim of this trial was to investigate the effect of melatonin on performance and mastitis in dairy cows. Forty-eight Holstein cows with a similar body weight (470 ± 10 kg), parity (2.75 ± 1.23), number of lactation days (143 ± 43 days), BCS (3.0-3.5), milk yield (36.80 ± 4.18 kg), and somatic cell count (300,000-500,000 cells/mL) were selected and randomly divided into four groups: control (CON group), trial Ⅰ (T80 group), trial Ⅱ (T120 group), and trial Ⅲ (T160 group). Twelve cows in trial groups I, II, and III were pre-dispensed 80, 120, and 160 mg of melatonin in edible glutinous rice capsules along with the basal ration, respectively, while the control group was fed an empty glutinous rice capsule along with the ration. The trial period was 37 days, which included a 7-day adaptive phase followed by a 30-day experimental period. At the end of the trial period, feeding was ended and the cows were observed for 7 days. Milk samples were collected on days 0, 7, 14, 21, 28, and 37 to determine the somatic cell number and milk composition. Blood samples were collected on days 0, 15, 30, and 37 of the trial to determine the serum biochemical indicators, antioxidant and immune indicators, and the amount of melatonin in the blood. The results showed that the somatic cell counts of lactating cows in the CON group were lower than those in the T120 group on days 14 (p < 0.05) and 28 (p < 0.01) at 1 week after melatonin cessation. The milk protein percentage and milk fat percentage of cows in the T120 group were higher than those in the CON group (p < 0.01). The total protein and globulin content in the T120 group were higher than those in the CON group (p < 0.01). In terms of antioxidant capacity and immunity, the cows 1 week after melatonin cessation showed higher superoxide dismutase activity and interleukin-10 contents (p < 0.01) compared with the CON group and lower malondialdehyde and tumor necrosis factor-alpha contents (p < 0.01) compared with the T120 group. The melatonin content in the T120 group was increased relative to that in the other groups. In conclusion, exogenous melatonin can increase the content of milk components, reduce the somatic cell count, and improve the antioxidant capacity and immune responses to a certain extent. Under the experimental conditions, 120 mg/day melatonin is recommended for mid- to late-lactation cows.

Genome-wide association studies for milk production traits in two autochthonous Aosta cattle breeds

Genome-wide association studies (GWASs) are used to identify quantitative trait loci for phenotypic traits of interest. The use of multilocus mixed models allows to correct for population stratification and account for long-range linkage disequilibrium. In this study, GWASs were conducted to identify the genetic bases of milk production (milk yield, protein and fat composition, and yield) in two autochthonous dual-purpose cattle breeds from the Aosta Valley. Using either the breeding values or the deregressed proofs, common significative single nucleotide polymorphisms have been identified for milk yield, protein percentage, and fat percentage. Two major quantitative trait loci regions have been identified on the chromosomes 5 and 14 for the fat percentage, harbouring the MGST1, CYHR1, VPS28, and CPSF1 genes. For the protein percentage, a candidate region has been identified on BTA 6; in this region, the CSN1S1, CSN2, HSTN, CSN3, and RUFY3 genes are annotated. Most of the identified genes have already been associated with milk composition in other studies on cosmopolitan and local cattle. These results show that the genes involved in milk composition quantitative traits in the Aosta cattle are common also in other cattle breeds and they can be further investigated with the use of whole genome sequencing data.

Stage of lactation, parity, breed, milk composition and minerals affect the non-enzymatic antioxidant activity of sheep milk

The aims of this study were to i) characterize sheep milk for non-enzymatic antioxidant activity via 2 different assays, namely the ferric reducing antioxidant power (FRAP) and the 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), and ii) investigate the effect of milk composition and animal-related parameters on these 2 assays by using Generalized Additive Mixed Model (GAMM) approach. A total of 740 ewes belonging to Massese and Comisana breeds were sampled once during the morning milking across 11 sampling sessions. All milk samples were analyzed for fat, protein, casein, and lactose, somatic cell score (SCS) and minerals (Ca, Mg, Na and Cl). The FRAP and DPPH assays were tested to measure the non-enzymatic antioxidant activity of milk, expressed as μM eq. ascorbic acid/mL of milk and % of inhibition, respectively. The GAMM model included the effect of parity and breed as parametric terms, and the effect of days in milk (DIM), milk yield and the interactions protein × fat, casein × SCS, Ca × Mg and Na × Cl as smooth terms. The sampling day was included in the model as random effect. Results revealed that the non-enzymatic antioxidant capacity of sheep milk, expressed as FRAP, was affected by DIM, potentially because of changes in milk composition over time. Conversely, parity and breed of ewes affected DPPH, suggesting that age- and breed-specific factors are related to specific components in milk acting as hydrogen donors. Milk fat and high casein percentages were found to significantly affect FRAP, while protein content was crucial for high DPPH levels. Additionally, Ca and Mg emerged as important non-enzymatic antioxidants for both FRAP and DPPH, highlighting their important role in antioxidant activity of sheep milk. On the other side, combinations of Na and Cl were particularly influential for FRAP, revealing the complex relationship between these minerals and non-enzymatic antioxidant activity of milk. These findings offer valuable insights into the factors affecting the antioxidative properties of sheep milk, highlighting the need for further exploration of other non-enzymatic antioxidants and their contribution to the total antioxidant activity.

The effects of dietary cation-anion difference and dietary buffer for lactating dairy cattle under mild heat stress with night cooling

The objective of this study was to investigate the interactive effect of dietary cation-anion difference (DCAD) and dietary buffer supply on DMI, ruminal fermentation, milk and milk component yields, and gastrointestinal tract (GIT) permeability in lactating dairy cattle exposed to mild heat stress. Sixteen lactating Holstein cows, including 8 ruminally cannulated primiparous (80 ± 19.2 DIM) and 8 non-cannulated multiparous (136 ± 38.8 DIM) cows, were housed in a tie-stall barn programmed to maintain a temperature-humidity index (THI) between 68 and 72 from 0600 h to 1600 h followed by natural night cooling. The experimental design was a replicated 4 × 4 Latin rectangle (21-d periods) with a 2 × 2 factorial treatment arrangement. Diets contained a low DCAD (LD; 17.5 mEq/100g of DM) or high DCAD (HD; 39.6 mEq/100g of DM) adjusted using NH4Cl and Na-acetate, with low (LB; 0% CaMg(CO3)2) or high buffer (HB; 1% CaMg(CO3)2). In addition to measurement of feed intake, ruminal fermentation, and milk and milk component yields, a ruminal dose of Cr-EDTA and an equimolar abomasal dose of Co-EDTA were used to evaluate total and post-ruminal gastrointestinal tract permeability, respectively. Treatments had no effect on DMI, ruminal short-chain fatty acid concentrations, or ruminal pH. Feeding HD improved blood acid-base balance, increased urine volume by 4 ± 1.5 kg/d, and increased milk fat by 0.14 ± 0.044 percentage units and milk fat yield by 36.5 ± 16.71 g/d. HB reduced milk fat percentage by 0.11 ± 0.044 percentage units and had no effect on milk fat yield. The HB treatments reduced urinary excretion of Co by 27% and tended to reduce urinary Cr excretion by 10%. Across all treatments, 72% of the Cr recovery was represented by Co suggesting that much of the permeability responses were post-ruminal during mild heat stress. In conclusion, increasing DCAD through greater Na supply during mild heat stress improved blood acid-base balance and may increase milk fat yield. Dietary inclusion of CaMg(CO3)2 improved post-ruminal GIT barrier function despite a lack of low ruminal pH. As there appeared to be a limited interactive effect between DCAD and buffer, increased DCAD and provision of buffer seem to independently influence physiological and performance responses in lactating dairy cows exposed to mild heat with night cooling.

Prediction of body condition score throughout lactation by random regression test-day models.

Regular monitoring of body condition score (BCS) changes during lactation is a crucial management tool in dairy cattle; however, the current BCS measurements are often discontinuous and unevenly spaced in time. The aim of this study was to investigate the ability of random regression test-day models (RR-TDM) to predict BCS for the entire lactation in dairy cows even if the actual scoring is limited to one BCS record. The data consisted of test-day records of milk yield (MY), fat percentage (FP), protein percentage (PP) and BCS (based on a 9-point scale with unit increments; 1-9) collected from 2014 to 2022 in 128 herds in the Walloon Region of Belgium. In total, 20,698 test-day records on 2166 first-parity Holstein cows (2-12 with an average of 9.42 test-day records per cow) were available for MY, FP and PP; and 7985 records on the same animals (2-12 with an average of 3.68 records per cow) were available for BCS. To estimate the solutions, only one randomly selected BCS record per animal along with all her MY, FP and PP records were used, which were then used to predict BCS data (calibration set). The remaining BCS (1-11 with an average 2.86 BCS records per animal) were used to evaluate the goodness of the predictions (validation set). Multiple-trait RR-TDM was used to estimate (co)variance components through the average information restricted maximum likelihood (AI-REML) algorithm. Predicted BCS were grouped into nine classes as the original observed BCS used for comparison. Pearson correlation between the predicted and observed BCS, prediction error (PE), absolute prediction error (APE) and root mean squared prediction error (RMSE) were calculated. Mean (standard deviation; SD) BCS was 4.97 (1.01), 4.95 (1.07) and 4.98 (1.00) BCS units in the full, calibration and validation datasets, respectively. Pearson correlation between the observed and predicted BCS was 0.71, mean (SD) PE was 0.04 (0.52) BCS units, mean (SD) APE was 0.48 (0.53) BCS units and RMSE was 0.72 BCS units. These findings demonstrate the ability of RR-TDM to predict BCS for the entire lactation using a single BCS record along with available test-day records of milk yield and composition in Holstein dairy cows.

Genome-wide copy number variation regions in indigenous (Bos indicus) cattle breeds of Tamil Nadu, India.

Identification of large scale structural polymorphisms (Copy number variations) of more than 50 bp between the individuals of a species would help in knowing genetic diversity, phenotypic variability, adaptability to tropical environment and disease resistance. Read depth-based method implemented in CNVnator was used for calling copy number variant regions on sequenced data obtained from WGS from 15 pooled samples belonging to five draught cattle breeds of Tamil Nadu. A total of 11,605 CNV regions (CNVRs) were observed covering a genome size of 18.63 percent. Among these, 11,459 were restricted to autosomes, consisting of 11,013 deletions, 353 duplications and 93 complex events. These CNVRs were annotated to 4,989 candidate genes. A total of 8,291 numbers of CNVRs were shared among the five cattle breeds as also supported by PCA and STRUCTURE analyses and 1,172 CNVRs were breed-specific. Four out of five selected breed-specific CNVRs were validated using real-time PCR. Genes with CNVRs are related to milk production (BTN1A1, ABCA1 and LAP3), disease resistance (TLR4 and DNAH8), adaptability (SOD1, CAST and SMARCAL1), growth (EGFR, NKAIN3), reproduction (BRWD1 and PDE6D), meat and carcass traits (MAP3K5 and NCAM1) and exterior (ATRN and MITF) traits. Gene enrichment analysis based on the gene list retrieved from the CNVRs disclosed over-represented terms (p<0.01) associated with milk fat production. NETWORK analysis had identified 13 putative candidate genes involved in milk fat percentage, milk fat yield, lactation persistency, milk yield, heat tolerance, calving ease, growth and conformation traits. The genome-wide CNVRs identified in the present study produced genome-wide partial CNV map in indigenous cattle breeds of Tamil Nadu.

Mitochondrial DNA D-loop SNPs unveil molecular signatures of milk production variation in Murrah buffalo.

The Murrah buffalo, pivotal in Asian agriculture, faces challenges in maximizing milk production despite significant breeding efforts. Recognizing its economic importance, this studyinvestigates mtDNA D-loop variations in Murrah buffalo as potential indicators of milk production variability, addressing challenges in maximizing yield despite significant breeding efforts. Analyzing mtDNA D-loop sequences from 50 buffaloes, we categorized them into Low (Group 1), Medium (Group 2), and High ECM (Group 3) groups based on milk yields, fat and protein percentage of a 30-day period data. Somatic cell mtDNA D-loop analysis revealed distinct genetic variations, with significant differences among ECM groups. Group 2 showed higher SNP prevalence, group 3 had more insertions/deletions, and Group 1 exhibited the highest transition frequency. Notably, a consistent "C" deletion at the 714th position occurred in Groups 1 and 3, prevalent in 68% of Group 2. A G-A variation at the 93rd position was specific to the medium ECM group. Negative Tajima D values indicated unique variations in each group, with Group 1 having the highest number, and a specific SNP linked to Group 2 was identified. These SNPs in the D-loop region could impact mtDNA replication, influencing mitochondrial content among animals. Our results provide valuable insights into the role of mtDNA D-loop polymorphisms in milk production traits in Murrah buffalo. Our research highlights the potential for valuable markers of cellular energy efficiency in Murrah buffalo. Exploring diverse cytoplasmic backgrounds opens avenues for mtDNA-based selection strategies, enhancing milk production and optimizing genetic traits for the dairy industry.

Rumen-protected methionine supplementation during the transition period under artificially induced heat stress: Effects on cow-calf performance

This study aimed to evaluate the effects of rumen-protected Met on lactation performance, inflammation and immune response, and liver glutathione of lactating dairy cows during a subclinical mastitis challenge (SMC). Thirty-two Holstein cows (145 ± 51 DIM) were enrolled in a randomized complete block design. At -21 d relative to the SMC, cows were assigned to dietary treatments, and data were collected before and during the SMC. Cows were blocked according to parity, DIM, and milk yield and received a basal diet (17.4% CP; Lys 7.01% MP and Met 2.14% MP) plus 100 g/d of ground corn (CON; n = 16) or a basal diet plus 100 g/d of ground corn and rumen-protected Met (SM, Smartamine M at 0.09% of dietary DM; n = 16), fed as a top-dress. At 0 d, the mammary gland's rear right quarter was infused with 100,000 cfu of Streptococcus uberis (O140J). Milk yield was recorded twice daily from 0 until 3 d relative to SMC. Milk samples were collected during each milking from 0 to 3 d relative to SMC, blood samples were collected at 0, 6, 12, 24, 48, and 72 h relative to SMC. The mTOR pathway activation was assessed in immune cells in blood and milk samples by measuring quantity and phosphorylation status of mTOR-related proteins, including AKT, S6RP, and 4EBP1. For the ratio of phosphorylated to total AKT, S6RP, and 4EBP1, blood samples were collected at 0, 12, and 24 h, and milk samples at 24 h relative to SMC. Liver biopsies were performed at -10 d and 24 h relative to SMC for measurement of glutathione. Linear mixed models with repeated measures were used to analyze the results. There was a trend for greater milk yield per milking (+ 0.8 kg) and per day (+1.7 kg) after SMC in SM cows compared with CON. The DMI was not affected by dietary treatments. Reactive oxygen metabolites (ROM) were lower in SM cows than in CON. Milk somatic cell linear score was not affected by dietary treatments, and a score >4 at 24 h confirmed subclinical mastitis. The SM cows had greater milk fat percentage at 24 and 36 h post SMC, resulting in overall greater milk fat. Milk protein tended to be greater in SM cows than in CON. We observed greater liver glutathione in SM cows than in CON. Among inflammation biomarkers, ceruloplasmin was lower for SM cows compared with CON. In milk, greater pAKT:AKT and pS6RP:S6RP ratios were observed in immune cell populations from SM cows compared with CON. Blood neutrophils had a greater p4EBP1:4EBP1 ratio in SM cows compared with CON. Overall, our results show that Met supplementation during an SMC positively affected milk performance, lowered the risk of oxidative stress, and attenuated inflammation partially by increasing liver glutathione and immune cells' protein synthesis via mTOR signaling.