Milk Protein Percentage Research Articles

The use of ensiled olive cake in the diets of Friesian cows increases beneficial fatty acids in milk and Halloumi cheese and alters the expression of SREBF1 in adipose tissue

This study aimed to evaluate the effect of dietary inclusion of ensiled olive cake, a by-product of olive oil production, on milk yield and composition and on fatty acid (FA) profile of milk and Halloumi cheese from cows. Furthermore, the effect of olive cake on the expression of selected genes involved in mammary and adipose lipid metabolism was assessed in a subset of animals. A total of 24 dairy cows in mid lactation were allocated into 2 isonitrogenous and isoenergetic feeding treatments, named the control (CON) diet and the olive cake (OC) diet, in which part of the forages (alfalfa, barley hay, and barley straw) were replaced with ensiled OC as 10% of dry matter according to a 2 × 2 crossover design with two 28-d experimental periods. At the end of the second experimental period, mammary and perirenal adipose tissue samples were collected from 3 animals per group for gene expression analysis by quantitative reverse-transcription PCR. The expression of 11 genes, involved in FA synthesis (ACACA, FASN, G6PDH), FA uptake or translocation (VLDLR, LPL, SLC2A1, CD36, FABP3), FA saturation (SCD1), and transcriptional regulation (SREBF1, PPARG), was evaluated. No significant differences were observed between groups concerning milk yield, fat percentage, protein percentage, and protein yield (kg/d), whereas milk fat yield (kg/d) increased in the OC group. Dietary supplementation with ensiled OC modified the FA profile of milk and Halloumi cheese produced. There was a significant decrease in the concentration of de novo synthesized FA, saturated FA, and the atherogenic index, whereas long-chain and monounsaturated FA concentration was increased in both milk and cheese. Among individual saturated FA, only stearic acid was elevated, whereas among individual monounsaturated FA, increments of oleic acid (C18:1 cis-9) and the sum of C18:1 trans-10 and trans-11 acids were demonstrated in milk and Halloumi cheese produced. Although no diet effect was reported on total polyunsaturated FA, the concentration of CLA cis-9,trans-11 was increased in both milk and Halloumi cheese fat of the OC group. The expression of the genes tested was unaffected apart from an observed upregulation of SREBF1 mRNA expression in perirenal fat from cows fed the OC diet. Milk FA differences observed were not associated with alterations in mammary expression of genes involved in FA synthesis, uptake, translocation, and regulation of lipogenesis. Overall, the inclusion of ensiled OC in cow diets for a 4-wk period improved, beneficially for human health, the lipid profile of bovine milk and Halloumi cheese produced without adversely affecting milk yield and composition or the expression of genes involved in lipid metabolism of mammary and adipose tissues in cows.

Meta-analysis for milk fat and protein percentage using imputed sequence variant genotypes in 94,321 cattle from eight cattle breeds

BackgroundSequence-based genome-wide association studies (GWAS) provide high statistical power to identify candidate causal mutations when a large number of individuals with both sequence variant genotypes and phenotypes is available. A meta-analysis combines summary statistics from multiple GWAS and increases the power to detect trait-associated variants without requiring access to data at the individual level of the GWAS mapping cohorts. Because linkage disequilibrium between adjacent markers is conserved only over short distances across breeds, a multi-breed meta-analysis can improve mapping precision.ResultsTo maximise the power to identify quantitative trait loci (QTL), we combined the results of nine within-population GWAS that used imputed sequence variant genotypes of 94,321 cattle from eight breeds, to perform a large-scale meta-analysis for fat and protein percentage in cattle. The meta-analysis detected (p ≤ 10−8) 138 QTL for fat percentage and 176 QTL for protein percentage. This was more than the number of QTL detected in all within-population GWAS together (124 QTL for fat percentage and 104 QTL for protein percentage). Among all the lead variants, 100 QTL for fat percentage and 114 QTL for protein percentage had the same direction of effect in all within-population GWAS. This indicates either persistence of the linkage phase between the causal variant and the lead variant across breeds or that some of the lead variants might indeed be causal or tightly linked with causal variants. The percentage of intergenic variants was substantially lower for significant variants than for non-significant variants, and significant variants had mostly moderate to high minor allele frequencies. Significant variants were also clustered in genes that are known to be relevant for fat and protein percentages in milk.ConclusionsOur study identified a large number of QTL associated with fat and protein percentage in dairy cattle. We demonstrated that large-scale multi-breed meta-analysis reveals more QTL at the nucleotide resolution than within-population GWAS. Significant variants were more often located in genic regions than non-significant variants and a large part of them was located in potentially regulatory regions.

Production response in dairy cows milked two or three times a day: A meta-analysis

The objective was to evaluate the effects of two (2×) vs three (3×) times per day milking on milk production and milk composition in dairy cows. Fourteen scientific papers, containing production data from 16 trials, where dairy cows were milked 2× or 3×, were analysed using meta-analysis with fixed and random-effects with the R statistical program. The degree of heterogeneity and publication bias were measured with the I2 statistic and Begg’s test, respectively. In addition, the meta-regression analysis explored other sources of heterogeneity for the response. The estimated effect size of 2× and 3× milkings was calculated for dry matter intake (DMI), milk production, and milk composition. Dry matter intake, milk production, and milk fat and protein yields showed substantial heterogeneity (I2>50%). Whereas milk fat-percentage had moderate heterogeneity (I2<50%), and milk protein had no (I2=0%)heterogeneity. The year of publication, trial duration, and cattle breed did not influence production response parameters to milking frequency. We found no evidence of publication bias for the parameters evaluated (Begg’s test; P>.05). Cows milked 2× produced less milk (2.23 kg/d), less milk fat (0.06kg/d), and less milk protein (0.05 kg/d). In contrast, the fat percentage was lower (0.07 units) in 3×, compared with 2× milking frequency. There was no effect of milking frequency on DMI and milk protein percentage. In conclusion, milk production and milk fat and protein yields improves as milking frequency increase from 2× to 3× daily, without affecting DMI. The implementation of 3× milking frequency must consider dairy cow management, labor, and milking parlour infrastructure, particular to each dairy farm.

A missense mutation in the coding region of the toll-like receptor 4 gene affects milk traits in Barki sheep.

ObjectiveMilk production is one of the most desirable traits in livestock. Recently, the toll-like receptor (TLR) has been identified as a candidate gene for milk traits in cows. So far, there is no information concerning the contribution of this gene in milk traits in sheep. This study was designed to investigate the TLR 4 gene polymorphisms in Barki ewes in Egypt and then correlate that with milk traits in order to identify potential single nucleotide polymorphisms (SNPs) for these traits in sheep.MethodsA part of the ovine TLR 4 gene was amplified in Barki ewes, to identify the SNPs. Consequently; Barki ewes were genotyped using polymerase chain reaction-single strand conformation polymorphism protocol. These genotypes were correlated with milk traits, which were the daily milk yield (DMY), protein percentage (PP), fat percentage (FP), lactose percentage, and total solid percentage (TSP).ResultsAge and parity of the ewe had a significant effect (p<0.05 or p<0.01) on DMY, FP, and TSP. The direct sequencing identified a missense mutation located in the coding sequence of the gene (rs592076818; c.1710C>A) and was predicted to change the amino acid sequence of the resulted protein (p.Asn570Lys). The association analyses suggested a significant effect (p<0.05) of the TLR genotype on the FP and PP, while the DMY tended to be influenced as well (p = 0.07). Interestingly, the presence of the G allele tended to increase the DMY (+40.5 g/d) and significantly (p<0.05 or p<0.01) decreased the FP (−1.11%), PP (−1.21%), and TSP (−7.98%).ConclusionThe results of this study suggested the toll-like receptor 4 (TLR4) as a candidate gene to improve milk traits in sheep worldwide, which will enhance the ability to understand the genetic architecture of genes underlying SNPs that affect such traits.

Grazing dairy cows with low milk urea nitrogen breeding values excrete less urinary urea nitrogen

There is an increasing pressure on temperate pastoral dairy production systems to reduce environmental impacts, coming from the inefficient use of N by cows in the form of excessive urinary N excretion and subsequent N leaching to the waterways and NO2 emissions to the atmosphere, these impacts have spurred research into various mitigation strategies, which have so far overlooked animal-based solutions. The objectives of this study were first, to investigate the relationship between MUN breeding values (MUNBV) and urinary urea N (UUN) concentrations and total excretion in grazing dairy cows; and secondly, to evaluate such a potential relationship in the context of different sward compositions and stage of lactation. Forty-eight multiparous, lactating Holstein-Friesian dairy cows genetically divergent for MUNBV were strip-grazed on either a ryegrass-white clover (24 cows) or ryegrass, white clover and plantain sward (24 cows), during both early and late lactation. Cows were fitted with Lincoln University PEETER sensors to evaluate urination behaviour by measuring frequency and volume of urination, as well as daily urine excretion. Urine and faeces were sampled for urea N content. Milk yield and composition were measured for individual cows in both periods. There was a positive relationship between MUNBV and MUN (R2 = 0.67, P ≤ 0.05), with MUN decreasing 1.61 ± 0.19 mg/dL per unit decrease in MUNBV across both sward types and stages of lactation. Urinary urea N concentration decreased 0.67 ± 0.27 g/L (R2 = 0.46, P ≤ 0.05) per unit decrease of MUNBV, with no effect on urine volume or frequency (number of urination events per day), which resulted in a 165.3 g/d difference in UUN excretion between the animal with the highest and the lowest MUNBV. At the same milk yield, percentage of protein in milk increased by 0.09 ± 0.03 (R2 = 0.61, P ≤ 0.05,) per unit decrease in MUNBV. Our results suggest that breeding and selecting for dairy cows with low MUNBV can reduce urinary urea N deposition onto pasture and consequently the negative environmental impact of pastoral dairy production systems in temperate grasslands. Moreover, reducing MUNBV of dairy cows can potentially increase farm profitability due to greater partitioning of N to milk in the form of protein.

Cooling and dietary crude protein affected milk production on heat-stressed dairy cows

Environmental factors, such as temperature and humidity, exert dramatic effects on the production, health, and well-being of lactating dairy cows. Heat-stressed cows undergo a series of homeorhetic adaptations that alters cellular homeostasis and nutrient utilization. The objective of this study was to determine the effects of cooling and dietary crude protein (CP) content on fermentability of rumen inoculum, milk production, and health of heat-stressed cows. It was hypothesized that cooled but not heat-stressed cows would support productivity in response to an increase in dietary CP content. Thirty-six multiparous Holstein cows were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement (9 cows/treatment). Treatments consisted of cooling (CO) or moderate long-term heat stress (HS) and diets containing low CP content (LCP; 12.5% CP) or moderate CP content (MCP; 16.1% CP) of dry matter. The CO treatment provided heat abatement with sprinklers and fans that came on at > 20.0°C, whereas the HS treatment did not provide sprinklers and fans. Cows were housed in pens in a freestall barn, and treatments were imposed for 21 d during July and August. Compared with the HS treatment, CO decreased afternoon rectal and vaginal temperatures (0.60 and 0.70°C) and afternoon respiration rate (27.6 breaths/min). Treatment interactions showed that compared with the LCP treatment, MCP increased milk fat yield (23%) in CO but not in HS cows. Compared with the LCP treatment, MCP decreased milk protein percent (0.14 units) in CO but increased milk protein percent (0.09 units) in HS cows. Rumen inoculum collected on d 21 showed a ~3-fold increase in total gas production in vitro in CO compared with the HS treatment. Relative to the LCP treatment, MCP increased plasma glucose and insulin and decreased total free fatty acids concentrations. In summary, under the conditions of this study CO but not HS cows responded to a CP stimulus by increasing productivity.

Mitigation of greenhouse gases in dairy cattle via genetic selection: 1. Genetic parameters of direct methane using noninvasive methods and proxies of methane

Records of methane emissions from 1,501 cows on 14 commercial farms in 4 regions of Spain were collected from May 2018 to June 2019. Methane concentrations (MeC) were measured using a nondispersive infrared methane detector installed within the feed bin of the automatic milking system during 14- to 21-d periods. Rumination time (RT; min/d) was collected using collars with a tag that registered time (minutes) spent eating and ruminating. The means of MeC and methane production (MeP) were 1,254.28 ppm and 182.49 g/d, respectively; mean RT was 473.38 min/d. Variance components for MeC, MeP, and RT were estimated with REML using pedigree and genomic information in a single-step model. Heritabilities for MeC and MeP were 0.11 and 0.12, respectively. Rumination time showed a slightly larger heritability estimate (0.17). The genetic correlation between MeP and MeC was high (>0.95), suggesting that selection on either trait would lead to a positive correlated response on the other. Negative correlations were estimated between RT and MeC (-0.24 ± 0.38) and MeP (-0.43 ± 0.35). Methane concentration and MeP had slightly positive correlations with milk yield (0.17 ± 0.39 and 0.21 ± 0.36), protein percentage (0.08 ± 0.32 and 0.30 ± 0.45), protein yield (0.22 ± 0.41 and 0.31 ± 0.35), fat percentage (0.02 ± 0.40 and 0.27 ± 0.36), and fat yield (0.27 ± 0.28 and 0.29 ± 0.28) from bivariate analyses. Rumination time had positive correlations with milk yield (0.41 ± 0.75) and protein yield (0.26 ± 0.57) and negative correlations with fat yield (-0.45 ± 0.32), protein percentage (-0.15 ± 0.38), and fat percentage (-0.40 ± 0.47). A positive approximated genetic correlation was estimated between fertility and MeC (0.10 ± 0.05) and MeP (0.18 ± 0.05), resulting in slightly higher CH4 production when selecting for better fertility [days open estimated breeding values (EBV) are expressed with mean 100 and SD 10, inversely related to days from calving to conception; that is, greater days open EBV implies better fertility]. Positive correlations were also estimated for stature with MeC and MeP (0.30 ± 0.04 and 0.43 ± 0.04, respectively). Other type traits (chest width, udder depth, angularity, and capacity) were positively correlated with methane traits, possibly because of higher milk yield and higher feed intake from these animals. Rumination time showed positive EBV correlations with production traits and type traits, and negative correlations with somatic cell count and body condition score. Based on the genetic correlations and heritabilities estimated in this study, methane is measurable and heritable, and estimates of genetic correlations suggest no strong opposition to current breeding objectives in Spanish Holsteins.

Variation in milk production, fat, protein, and lactose responses to exogenous feed enzymes in dairy cows

ABSTRACT Objective Our objectives were to evaluate milk production and constituent responses to changes in the diet for pens of cows over time and whether differences in response were attributable to fibrolytic enzymes and dairy. Materials and Methods A multiherd trial used 7,507 cows in 8 control and enzyme-treated (750 mL/t of DM feed) replicates (16 pens) on 3 dairies. Feed composition and milk production and constituents by pen (n = 12) were analyzed weekly. Time-series cross-correlation estimates by pen of feed component intakes (kg/d) and milk responses were pooled to produce effect size (ES) estimates. Results and Discussion We observed differences between treatment and control pens for soluble protein (ES = 0.249) in the same week, acid detergent–insoluble CP (ES = 0.293) and lignin (ES = 0.237) 1 wk before with milk protein percentage, and acid detergent–insoluble CP (ES = 0.276) and lignin (ES = 0.246) 1 wk before with milk protein yield. These differences are consistent with enzymes improving feed digestibility, particularly for protein and fiber fractions. Differences in production responses to intake of feed components among dairies were observed. More significant and larger differences occurred among dairies than for treatments. The dairy that increased milk production most with treatment had an estimated MP excess from the diet, whereas the least responsive had an estimated MP-deficit diet and was the highest producing. Implications and Applications We provide evidence for variability in enzyme response and that changes in dietary feed components influence production outcomes immediately and up to 3-wk later.

Effects of eight InDel variants in FHIT on milk traits in Xinjiang brown cattle

In our previous genome-wide association study (GWAS), we identified the fragile histidine triad diadenosine triphosphatase (FHIT) gene in Xinjiang brown cattle (XJBC) as a candidate gene associated with cattle productive traits, with potential application in mark-assisted selection (MAS) in cattle breeding. FHIT is a prototype of a class of tumor suppressor genes that contain genomic loci mapped to common fragile loci. Here, 388 healthy and unrelated XJBC were selected to identify insertion/deletion (InDel) variants in the bovine FHIT and assess their effects on milk traits. Eight of the thirteen InDel loci were found to be polymorphic in FHIT. The polymorphism information content of the eight loci ranged from 0.061 to 0.375. The correlation analysis showed that all the new InDel variants were significantly related to six different milk traits (p < 0.05). The following variants presented a significant relationship with productive traits: P2-23bp with the 305 milk yield (p = 0.005) in the sixth parity; P3-24bp with the milk fat yield (p = 0.009) in the third parity; P5-21bp with the somatic cell score (p = 0.001) in the first parity and with the milk protein percentage (p = 0.002) in the sixth parity; and P7-26bp with the somatic cell score (p = 0.003) in the sixth parity. These findings will help evaluate InDel genotypes, within and between cattle breeds and identify potential target loci to accelerate progress in MAS in cattle breeding.

Heritability estimates of predicted blood β-hydroxybutyrate and nonesterified fatty acids and relationships with milk traits in early-lactation Holstein cows

At the beginning of lactation, high-producing cows commonly experience an unbalanced energy status that is often responsible for the onset of metabolic disorders and impaired health and performance. Blood β-hydroxybutyrate (BHB) and nonesterified fatty acids (NEFA) are indicators of excessive fat mobilization and circulating ketone bodies. Recently, prediction models based on mid-infrared (MIR) spectroscopy have been developed to assess blood BHB and NEFA from routinely collected individual milk samples. This study aimed to estimate genetic parameters of blood BHB and NEFA predicted from milk MIR spectra and to assess their phenotypic and genetic correlations with milk production and composition traits in early-lactation Holstein cows. The data set comprised the first test-day record within lactation and spectra of individual milk samples (n = 22,718) of 13,106 Holstein cows collected from 5 to 35 d in milk (DIM). Blood BHB and NEFA were predicted from milk MIR spectra using previously developed prediction models. Genetic parameters of blood metabolites and milk traits were estimated for the whole observational period (5-35 DIM) and within 6 classes of DIM. Blood BHB and NEFA showed similar genetic variation across DIM, with the highest heritability in the first 10 d after calving (0.31 ± 0.06 and 0.19 ± 0.05 for BHB and NEFA, respectively). The genetic correlation between BHB and NEFA was moderate (0.51 ± 0.05). Genetic correlations of BHB with milk yield, SCS, protein percentage, lactose percentage, and urea nitrogen content were similar to, or at least in the same direction as, the correlations of NEFA with the same traits, whereas opposite correlations were observed with fat percentage and fat-to-protein ratio. Results of the current study suggest that blood BHB and NEFA predicted from milk MIR spectra have genetic variation that is potentially exploitable for breeding purposes. Therefore, they could be used as indicator traits of hyperketonemia in a selection index aimed to reduce the susceptibility of dairy cows to metabolic disorders in early lactation.

High levels of fatty acids inhibit β-casein synthesis through suppression of the JAK2/STAT5 and mTOR signaling pathways in mammary epithelial cells of cows with clinical ketosis.

Ketosis is a metabolic disease of dairy cows often characterized by high concentrations of ketone bodies and fatty acids, but low milk protein and milk production. The Janus kinase 2 (JAK2)-signal transducer and activator of transcription 5 (STAT5) and the mechanistic target of rapamycin (mTOR) signaling pathways are central for the regulation of milk protein synthesis. The effect of high levels of fatty acids on these pathways and β-casein synthesis are unknown in dairy cows with clinical ketosis. Mammary gland tissue and blood samples were collected from healthy (n = 15) and clinically-ketotic (n = 15) cows. In addition, bovine mammary epithelial cells (BMEC) were treated with fatty acids, methionine (Met) or prolactin (PRL), respectively. In vivo, the serum concentration of fatty acids was greater (P > 0.05) and the percentage of milk protein (P > 0.05) was lower in cows with clinical ketosis. The JAK2-STAT5 and mTOR signaling pathways were inhibited and the abundance of β-casein was lower in mammary tissue of cows with clinical ketosis (P > 0.05). In vitro, high levels of fatty acids inhibited the JAK2-STAT5 and mTOR signaling pathways (P > 0.05) and further decreased the β-casein synthesis (P > 0.05) in BMEC. Methionine or PRL treatment, as positive regulators, activated the JAK2-STAT5 and mTOR signaling pathways to increase the β-casein synthesis. Importantly, the high concentration of fatty acids attenuated the positive effect of Met or PRL on mTOR, JAK2-STAT5 pathways and the abundance of β-casein (P > 0.05). Overall, these data indicate that the high concentrations of fatty acids that reach the mammary cells during clinical ketosis inhibit mTOR and JAK2-STAT5 signaling pathways, and further suppress β-casein synthesis.

Critical Review of Dairy Cow Industry in the World

Critical Review of Dairy Cow Industry in the World

Physiologic responses to feeding rumen-protected glucose to lactating dairy cows

It was hypothesized that rumen-protected glucose (RPG) in diets of dairy cows increases concentrations of insulin resulting in greater blood progesterone concentrations because elevated insulin decreases activity of liver enzymes inactivating steroid hormones. Timing of ovulation was synchronized among 64 postpartum Holstein cows using GnRH and PGF2α (Day 0 = ovulation). Cows were milked thrice daily and assigned randomly a basal diet supplemented with 0, 1, 2, or 4 kg of an RPG product in place of corn grain, top-dressed in the diet beginning on Day -3. Blood was collected pre- and post-prandial on Days 0, 2, and 4 to determine plasma glucose and insulin concentrations and daily from Days 2 through 12. Intake of crude protein and energy-soluble carbohydrates increased linearly with dose, whereas starch intake decreased linearly with dose. Neither daily milk yield nor dry matter intake (DMI), energy-corrected milk (ECM), somatic cell count, or percentages of milk fat, protein and lactose on Day 8 differed among dietary treatments. Neither pre- nor post-prandial changes in plasma glucose differed among treatments. In contrast, post-prandial glucose decreased from Days 0 through 4. A change in plasma insulin (post-prandial minus pre-prandial) was detected. Milk urea nitrogen increased linearly with RPG dose. Concentrations of progesterone were unaffected by RPG dose. It is concluded that insulin response to RPG was decreased relative to the control and RPG supplementation linearly increased crude protein intake and milk urea nitrogen with increasing dose, but did not affect concentrations of progesterone, milk yield, or dry matter intake.

Sorghum silage substituted for corn silage in diets for dairy cows: Effects on feed intake, milk yield and quality, and serum metabolites

ABSTRACT Objective Whole-plant corn silage (CS) is the main forage fed to dairy cows in China, usually comprising about 35% of the total DM of the TMR. However, sorghum is more resistant to drought and tolerates soils that are less fertile compared with corn, and consequently, sorghum silage (SS) would be preferable to CS in many drought-prone areas of China. Sweet SS is characterized by a high content of water-soluble carbohydrates and energy yield. Previous studies examined the effects of feeding either CS or SS in the TMR of lactating cows. The aim of the present study was to assess the effects of substituting different levels of sweet SS for CS in the TMR fed to dairy cows in a smallholder farm in western China. Materials and Methods Sixteen multiparous Holstein cows (mean BW of 454 ± 25 kg), producing approximately 12 kg/d milk, were assigned randomly to 4 dietary treatments. Experimental diets were formulated to be iso-energetic and iso-nitrogenous with 45% forage and 55% concentrate, and the diets included 10% oat hay and variable proportions of CS and SS. Dietary treatments included (1) 100% CS (35% DM of TMR, control diet); (2) 35% of CS replaced by SS; (3) 65% of CS replaced by SS; and (4) 100% of CS replaced by SS. Results and Discussion The DMI decreased linearly (P = 0.002) as SS increased. Milk yield and lactose percentage did not differ among treatments, but lactose yield exhibited a cubic response (P = 0.004), whereas milk fat percentage tended to increase linearly (P = 0.077) as SS increased. Increasing SS resulted in a quadratic response in milk protein percentage and yield (P = 0.001) and MUN increased linearly as SS increased (P = 0.022). The ECM/DMI ranged between 0.75 and 0.82 and increased linearly as SS increased (P = 0.029). Although there were differences among treatments in serum concentrations of aspartate transaminase, alanine aminotransferase, alkaline phosphatase, urea nitrogen, and glucose, all concentrations were in the normal range for healthy, lactating cows. Serum β-hydroxybutyric acid concentrations were well below the subclinical levels in all treatments. The SCC decreased linearly (P = 0.024) with increasing SS. Implications and Applications We concluded that for low-producing dairy cows, SS can replace CS in total in the diet without adverse effects on milk yield and its components and on serum metabolites. This is particularly important for small dairy herds in dry areas.

Effect of Feeding Hazelnut Skin on Animal Performance, Milk Quality, and Rumen Fatty Acids in Lactating Ewes.

Simple SummaryThe by-products originating from the agro-industry processes are often rich in bioactive compounds. This is the case of hazelnut skin, waste biomass of the pastry industry, rich in polyphenols and fatty acids that, if included in animal feeding, could contribute (i) to improve animal health and products’ quality and (ii) to reduce the feed costs and feed-to-food competition in animal production. We tested this by-product as an ingredient of the diet for lactating ewes. Noteworthy, despite we observed a slight reduction of milk protein percentage, the dietary administration of hazelnut skin improved the composition of the milk lipid fraction by increasing the presence of health-promoting fatty acids and by reducing atherogenic fatty acids. Also, a healthier status of the udder could be hypothesized as a consequence of the inclusion of hazelnut skin in the diet of lactating ewes.The hazelnut skin is waste biomass rich in bioactive compounds that may affect lipid rumen metabolism, ruminant performance, and products’ quality. Therefore, we investigated the effect of dietary hazelnut skin on milk production and composition and on rumen fatty acids in ewes. During 28 days, 20 Comisana lactating ewes received alfalfa hay ad libitum plus 800 g/head/day of pelleted concentrate containing 36% dried beet pulp (CTRL group; n = 10) or 36% hazelnut skin (HS group; n = 10). The protein percentage was lower in HS milk. Milk fatty acids (FA) partially reflected those of rumen content. Total saturated FA (SFA), odd and branched-chain FA, and n-3 polyunsaturated FA (PUFA) were greater in CTRL milk. Total monounsaturated FA (MUFA) and 18:1 trans were greater in HS milk; moreover, HS milk showed a double percentage of oleic acid than the CTRL group. Individual SFA were greater in CTRL milk except for 18:0. Differing from the rumen content, total PUFA, n-6 PUFA, and 18:2 n-6 were comparable between groups. Vaccenic and rumenic acid were greater in HS milk. To conclude, dietary HS slightly reduced milk protein percentage but improved atherogenic index and healthy FA in milk. The content of the somatic cells suggested a healthier udder in the HS group.

Genome-wide identification of Diacylglycerol Acyltransferases (DGAT) family genes influencing Milk production in Buffalo

BackgroundThe diacylglycerol acyltransferases (DGAT) are a vital group of enzymes in catalyzing triacylglycerol biosynthesis. DGAT genes like DGAT1 and DGAT2, have been identified as two functional candidate genes affecting milk production traits, especially for fat content in milk. Buffalo milk is famous for its excellent quality, which is rich in fat and protein content. Therefore, this study aimed to characterize DGAT family genes in buffalo and to find candidate markers or DGAT genes influencing lactation performance.ResultsWe performed a genome-wide study and identified eight DGAT genes in buffalo. All the DGAT genes classified into two distinct clades (DGAT1 and DGAT2 subfamily) based on their phylogenetic relationships and structural features. Chromosome localization displayed eight buffalo DGAT genes distributed on five chromosomes. Collinearity analysis revealed that the DGAT family genes were extensive homologous between buffalo and cattle. Afterward, we discovered genetic variants loci within the genomic regions that DGAT genes located in buffalo. Seven haplotype blocks were constructed and were associated with buffalo milk production traits. Single marker association analyses revealed four most significant single nucleotide polymorphisms (SNPs) mainly affecting milk protein percentage or milk fat yield in buffalo. Genes functional analysis indicated that these DGAT family genes could influence lactation performance in the mammal through regulating lipid metabolism.ConclusionIn the present study, we performed a comprehensive analysis for the DGAT family genes in buffalo, which including identification, structural characterization, phylogenetic classification, chromosomal distribution, collinearity analysis, association analysis, and functional analysis. These findings provide useful information for an in-depth study to determine the role of DGAT family gens play in the regulation of milk production and milk quality improvement in buffalo.

EFFECT OF USING SODIUM BICARBONATE AND MIXTURE OF VITAMIN E AND SELENIUM IN PRODUCTION PERFORMANCE OF AWASSI EWES

This study was conducted by using18 Awassiewes , 2-4 years aged, with average body weight 61.56 kg. The ewes were randomly divided into three groups, six ewes in each group. All ewes received 1.5 kg/ dry matter from the same basal diet consist mainly of barley, wheat bran, soybean meal and wheat straw . The first group was fed on basal ration only ( T1 ) ,while 45g /ewe /day sodium bicarbonate was supplemented to the feed of the second (T2)group and third (T3) group was supplemented with 45g sodium bicarbonate plus 0.5g mixture of Vitamin E and selenium /ewe/day. Results showed that the treatments hadsignificant increase( P &lt; 0.05 ) on milk production of T3(739 g/d) than T1,T2(571and 599 g/d)respectively. No effect on average body weight, lactose, fat and protein percentage in milk. Rumen liquor pH, ammonia and total count of rumen bacteria and protozoa before feeding was not affected, while after 2hr of feeding, pH value of rumen liquor was increased (P &lt; 0.05) in T2 6.65 as compared with T1 5.62 and T3 6.13. Ammonia and microorganism concentration in rumen liquor and blood parameters were not affected by experimental treatments.

Association of UDP-galactose-4-epimerase with milk protein concentration in the Chinese Holstein population.

ObjectiveAn initial RNA-Sequencing study revealed that UDP-galactose-4-epimerase (GALE) was one of the most promising candidates for milk protein concentration in Chinese Holstein cattle. This enzyme catalyzes the interconversion of UDP-galactose and UDP-glucose, an important step in galactose catabolism. To further validate the genetic effect of GALE on milk protein traits, genetic variations were identified, and genotypes-phenotypes associations were performed.MethodsThe entire coding region and the 5′-regulatory region (5′-UTR) of GALE were re-sequenced using pooled DNA of 17 unrelated sires. Association studies for five milk production traits were performed using a mixed linear animal model with a population encompassing 1,027 Chinese Holstein cows.ResultsA total of three variants in GALE were identified, including two novel variants (g.2114 A>G and g.2037 G>A) in the 5′-UTR and one previously reported variant (g.3836 G>C) in an intron. All three single nucleotide polymorphisms (SNPs) were associated with milk yield (p<0.0001), fat yield (p = 0.0006 to <0.0001), protein yield (p = 0.0232 to <0.0001) and protein percentage (p<0.0001), while no significant associations were detected between the SNPs and fat percentage. A strong linkage disequilibrium (D’ = 0.96 to 1.00) was observed among all three SNPs, and a 5 Kb haplotype block involving three main haplotypes with GAG, AGC, and AGG was formed. The results of haplotype association analyses were consistent with the results of single locus association analysis (p<0.0001). The phenotypic variance ratio above 3.00% was observed for milk protein yield that was explained by SNP-g.3836G >C.ConclusionOverall, our findings provided new insights into the polymorphic variations in bovine GALE gene and their associations with milk protein concentration. The data indicate their potential uses for marker-assisted breeding or genetic selection schemes.

SERPINA1 gene identified in RNA-Seq showed strong association with milk protein concentration in Chinese Holstein cows.

The detection of candidate genes and mutations associated with phenotypic traits is important for livestock animals. A previous RNA-Seq study revealed that SERPINA1 gene was a functional candidate that may affect milk protein concentration in dairy cows. To further confirm the genetic effect of SERPINA1 on milk protein traits, genetic polymorphisms were identified and genotype-phenotype associations were performed in a large Chinese Holstein cattle population. The entire coding region and the 5′-regulatory region (5′-UTR) of SERPINA1 was sequenced using pooled DNA of 17 unrelated sires. Association studies for five milk production traits were performed using a mixed model with a population encompassing 1,027 Chinese Holstein cows. A total of four SNPs were identified in SERPINA1, among which rs210222822 and rs41257068 presented in exons, rs207601878 presented in an intron, and rs208607693 was in the 5′-UTR. Analyses of pairwise D′ measures of linkage disequilibrium (LD) showed strong linkage among these four SNPs (D′ = 0.99–1.00), and a 9 Kb haplotype block involving three main haplotypes with GTGT, CCCC and CCGT was inferred. An association study revealed that all four single SNPs and their haplotypes had significant genetic effects on milk protein percentage, milk protein yield and milk yield (P = 0.0458 − < 0.0001). The phenotypic variance ratio for all 11 significant SNP-trait pairs ranged from 1.01% to 7.54%. The candidate gene of SERPINA1 revealed by our previous RNA-Seq study was confirmed to have pronounced effect on milk protein traits on a genome level. Two SNPs (rs208607693 and rs210222822) presented phenotypic variances of approximately 7% and may be used as key or potential markers to assist selection for new lines of cows with high protein concentration.

The Effects of Dietary Supplementation of Saccharomyces cerevisiae Fermentation Product During Late Pregnancy and Lactation on Sow Productivity, Colostrum and Milk Composition, and Antioxidant Status of Sows in a Subtropical Climate.

This study aimed to evaluate the effects of dietary supplementation of Saccharomyces cerevisiae fermentation product (SCFP) during late pregnancy and lactation on sow productivity, colostrum and milk composition, and antioxidant status of sows in a subtropical climate. The study was a 2 × 2 factorial treatment design where the first factor was environmental THI level [Low THI (08:00–19:00: 70.76 ± 0.45, 19:00–08:00: 67.91 ± 0.18, L-THI) or High THI (08:00–19:00: 75.14 ± 0.98, 19:00–08:00: 68.35 ± 0.18, H-THI], and the second factor was dietary treatment (supplemented with or without 3 kg/t SCFP). A total of 120 sows were randomly allotted to the four treatments (n = 30). The feeding trial was conducted from 85-days post-breeding until 21-days post-partum. Compared with L-THI group, sows from H-THI group had lesser individual piglet birth weight, individual piglet weight at weaning, preweaning average daily gain of piglets, average daily feed intake of sows during lactation, and protein percentage in 14-days milk. Additionally, sows from H-THI group had lesser antioxidant status, indicated by lesser serum total antioxidant capacity (T-AOC), and superoxide dismutase (SOD) activity at parturition; lesser serum T-AOC and glutathione peroxidase (GSH-Px) activity at 14-days post-partum, as well as lesser SOD activity in colostrum. Compared with sows fed the control diet, sows fed the SCFP diet had greater number of piglets weaned, litter weight at weaning, and preweaning average daily gain of piglets. Moreover, sows fed the SCFP diet had improved antioxidant status as indicated by higher serum T-AOC at parturition, and lesser malondialdehyde (MDA) content in colostrum and 21-days milk. In conclusion, H-THI negatively affected the productivity, milk composition, antioxidant status, and lactation feed intake of sows. Dietary supplementation of SCFP partially alleviated the adverse effects of H-THI, by improving lactation performance and antioxidant status of sows without influencing reproductive performance and colostrum and milk composition in a subtropical climate.