Ketosis Treatment and Milk Yield in Dairy Cows Related to Milk Acetoacetate Levels

Milk yield and milk acetoacetate (M-acac) were measured weekly for the first 6 weeks of lactation in 5 herds with a ketosis problem. Ketosis treatments and the corresponding ketotest score, were also recorded. The treatment rate was highest 7–16 days after calving. Most of these early cases were associated with low ketone levels in milk, whereas the treatment ratefor cows with high ketone levels was highest 17–31 days after calving. Nearly half of the treated cows were low-ketone animals. They were classified as ketosis cases in the cow health card records, although probably suffering from other post partum disturbances in many instances. About 40 % of the cows with high ketone levels recovered spontaneously. Reduction in milk yield associated with peak M-acac levels was transient and moderate. It was concluded that health card statistics overestimates the severity of the ketosis problem in Norway.     

Polymorphisms of Mitochondrial ATPASE 8/6 Genes and Association with Milk Production Traits in Holstein Cows

The maternal effect has been widely proposed to affect the production traits in domestic animals. However, the sequence polymorphisms of mitochondrial DNA (mtDNA) and association with milk production traits in Holstein cows have remained unclear. In this study, we investigated the single nucleotide polymorphisms (SNPs) of mtDNA ATPase 8/6 genes and association with four milk production traits of interest in 303 Holstein cows. A total of 18 SNPs were detected among the 842 bp fragment of ATPase 8/6 genes, which determined six haplotypes of B. taurus (H1-H4) and B. indicus (H5-H6). The mixed model analysis revealed that there was significant association between haplotype and 305-day milk yield (MY). The highest MY was observed in haplotype H4. However, we did not detect statistically significant differences among haplotypes for the traits of milk fat (MF), milk protein (MP), and somatic cell count (SC). The overall haplotype diversity and nucleotide diversity of ATPase 8/6 genes were 0.563 ± 0.030 and 0.00609 ± 0.00043, respectively. The results suggested that mitochondrial ATPase 8/6 genes could be potentially used as molecular marker to genetically improve milk production in Holstein cows.     

Effect of Concentrate Crude Protein Level on Grass Silage Intake,Milk Yield and Nutrient Utilisation by Dairy Cows in Early Lactation

Twenty-one multiparous dairy cows were fed concentrates containing three levels (119, 154 and 191g/kg DM) of crude protein (CP) during the first ten weeks of lactation. Part of the grain and molassed sugar beat pulp was substituted with 0% (RSM0), 15% (RSM15) or 30% (RSM30) rapeseed meal. Wilted grass silage was fed ad libitum after calving. The average response between RSM0 and RSM15 was +1.66kg milk/d per percentage unit change in concentrate CP content. No further response occurred between RSM15 and RSM30. The positive effect of RSM inclusion was seen throughout the experimental period and was associated with increased plasma non esterified fatty acids (NEFA) and decreased plasma insulin concentration one week after calving, and higher efficiency of metabolisable energy utilisation for milk production. Digestibility of the diet remained unaffected. Milk and plasma urea tended to increase with RSM30 indicating excessive supply of rumen degradable protein. Because of the limited potential of cows to compensate for a deficit in feed protein supply by mobilising tissue protein, a substantial milk yield response can be achieved with a moderate level of protein supplementation during early lactation.     

Effect of Zinc Methionine or Zinc Sulfate Supplementation on Milk Production and Composition of Milk in Lactating Dairy Cows

Eighteen lactating dairy cows were used to compare the effects of organic and inorganic Zn supplements on milk production and chemical composition of milk. Animals received three diets in a randomized block design: basal diet with no supplemental Zn (control, 42 mg Zn/kg), basal diet plus 500 mg Zn/kg of dry matter (DM) as zinc sulfate monohydrate (ZnS) and basal diet plus 500 mg Zn/kg of DM as zinc methionine (ZnM). Results showed that milk and fat-corrected milk yield in dairy cows were not significantly affected by Zn source although a numerical increase was observed. The percentages of protein, lactose, fat, solid nonfat, total solid, and density of milk were not significantly different between treatments. However, dairy cows that received ZnM tended to produce more milk and fat-corrected milk with a lower somatic cell count as compared to controls. The zinc concentration in milk in the ZnM and ZnS groups was higher (P < 0.05) than in milk from the control group, but there were no significant differences between ZnS and ZnM groups.     

奶牛HSP70基因3'-侧翼区多态性分析及其与生产性能的关系

以160头荷斯坦和娟姗奶牛作为研究对象,分别测定了其在不同温度条件下,直肠温度、呼吸频率、产奶量及乳成分,并进行了统计分析。同时设计引物扩增HSP70基因3’-侧翼区,通过PCR—SSCP技术分析hSPTO基因3’-侧翼区的多态性,并发现一个多态位点。结果表明：扩增片段为292bp,扩增产物有基因多态性,共发现4种基因型,分别为荷斯坦牛的AA（H）型、AB（H）型和娟姗牛的AA（J）刭、AB（J）型。其中B基因可能为抗热应激耩囚,这4种基囚型奶牛个体的生产性能差异不显著（P〉0．05）。     

Metabolic Heat Stress Adaption in Transition Cows: Differences in Macronutrient Oxidation between Late-Gestating and Early-Lactating German Holstein Dairy Cows

High ambient temperatures have severe adverse effects on biological functions of high-yielding dairy cows. The metabolic adaption to heat stress was examined in 14 German Holsteins transition cows assigned to two groups, one heat-stressed (HS) and one pair-fed (PF) at the level of HS. After 6 days of thermoneutrality and ad libitum feeding (P1), cows were challenged for 6 days (P2) by heat stress (temperature humidity index (THI) = 76) or thermoneutral pair-feeding in climatic chambers 3 weeks ante partum and again 3 weeks post-partum. On the sixth day of each period P1 or P2, oxidative metabolism was analyzed for 24 hours in open circuit respiration chambers. Water and feed intake, vital parameters and milk yield were recorded. Daily blood samples were analyzed for glucose, β-hydroxybutyric acid, non-esterified fatty acids, urea, creatinine, methyl histidine, adrenaline and noradrenaline. In general, heat stress caused marked effects on water homeorhesis with impairments of renal function and a strong adrenergic response accompanied with a prevalence of carbohydrate oxidation over fat catabolism. Heat-stressed cows extensively degraded tissue protein as reflected by the increase of plasma urea, creatinine and methyl histidine concentrations. However, the acute metabolic heat stress response in dry cows differed from early-lactating cows as the prepartal adipose tissue was not refractory to lipolytic, adrenergic stimuli, and the rate of amino acid oxidation was lower than in the postpartal stage. Together with the lower endogenous metabolic heat load, metabolic adaption in dry cows is indicative for a higher heat tolerance and the prioritization of the nutritional requirements of the fast-growing near-term fetus. These findings indicate that the development of future nutritional strategies for attenuating impairments of health and performance due to ambient heat requires the consideration of the physiological stage of dairy cows.     

DGAT-1基因K232A突变位点对甘肃地区中国荷斯坦牛泌乳性状的影响

为探索二酰甘油酰基转移酶(DGAT-1)基因多态性与奶牛泌乳性状的相关性,以232头甘肃地区中国荷斯坦牛为实验材料,利用PCR-SSCP技术并结合测序研究DGAT-1基因K232A位点遗传多态性,采用混合动物模型分析DGAT-1基因K232A突变位点对305 d产奶量、305 d乳脂量和305 d乳蛋白量的影响。结果表明:DGAT-1基因K232A位点共存在KK、KA和AA三种基因型,频率分别为0.5086、0.3750和0.1164,等位基因K和A的频率分别为0.6961和0.3039,多态信息含量(PIC)为0.3336,实验群体在这一位点上处于Hardy-Weinberg平衡状态。该位点突变对305 d产奶量的影响达到极显著水平(P<0.01),对305 d乳脂量和305 d乳蛋白量的影响达到显著水平(P<0.05)。最小二乘法分析表明,AA和KA型305 d产奶量极显著高于KK型(P<0.01),KK型乳脂量显著高于AA和KA型(P<0.05),AA型乳蛋白量显著高于KK型(P<0.05);A等位基因是提高产奶量和乳蛋白量的优势基因,而K等位基因是高乳脂量的优势基因。DGAT-1基因K232A位点突变对甘肃地区中国荷斯坦牛泌乳性状有较大的遗传效应,可用于其泌乳性状的分子标记辅助选择。     

Influence of DGAT1 K232A Polymorphism on Milk Fat Percentage and Fatty Acid Profiles in Romanian Holstein Cattle

Milk and dairy products are considered the main sources of saturated fatty acids, which are a valuable source of nutrients in the human diet. Fat composition can be adjusted through guided nutrition of dairy animals but also through selective breeding. Recently, a dinucleotide substitution located in the exon 8 of the gene coding for acyl CoA: diacylglycerol acyltransferase 1 (DGAT1), that alters the amino acid sequence from a lysine to an alanine (p.Lys232Ala) in the mature protein, was shown to have a strong effect on milk fat content in some cattle breeds. Therefore, the objectives of this work were to study the occurrence of the DGAT1 p.Lys232Ala polymorphism in Romanian Holstein cattle and Romanian Buffalo breeds and to further investigate its possible influence on fat percentage and fatty acid profiles. The results obtained in this study show that in Romanian Holstein cattle the K allele is associated with increased fat percentage and higher levels of C16:0 and C18:0 fatty acids. The ratio of saturated fatty acids versus unsaturated fatty acids (SFA/UFA) was also higher in KK homozygous individuals, whereas the fractions of C14:0, unsaturated C18 decreased. The DGAT1 p.Lys232Ala polymorphism revealed a high genetic variance for fat percentage, unsaturated C18, C16:0, and SFA/UFA. Although the effect of this polymorphism was not so evident for short chain fatty acids such as C4:0–C8:0, it was significant for C14:0 fatty acids. We concluded that selective breeding of carriers of the A allele in Romanian Holsteins can contribute to improvement in unsaturated fatty acids content of milk. However, in buffalo, the lack of the A allele makes selection inapplicable because only the K allele, associated with higher saturated fatty acids contents in milk, was identified.     

Integrating Milk Metabolite Profile Information for the Prediction of Traditional Milk Traits Based on SNP Information for Holstein Cows

In this study the benefit of metabolome level analysis for the prediction of genetic value of three traditional milk traits was investigated. Our proposed approach consists of three steps: First, milk metabolite profiles are used to predict three traditional milk traits of 1,305 Holstein cows. Two regression methods, both enabling variable selection, are applied to identify important milk metabolites in this step. Second, the prediction of these important milk metabolite from single nucleotide polymorphisms (SNPs) enables the detection of SNPs with significant genetic effects. Finally, these SNPs are used to predict milk traits. The observed precision of predicted genetic values was compared to the results observed for the classical genotype-phenotype prediction using all SNPs or a reduced SNP subset (reduced classical approach). To enable a comparison between SNP subsets, a special invariable evaluation design was implemented. SNPs close to or within known quantitative trait loci (QTL) were determined. This enabled us to determine if detected important SNP subsets were enriched in these regions. The results show that our approach can lead to genetic value prediction, but requires less than 1% of the total amount of (40,317) SNPs., significantly more important SNPs in known QTL regions were detected using our approach compared to the reduced classical approach. Concluding, our approach allows a deeper insight into the associations between the different levels of the genotype-phenotype map (genotype-metabolome, metabolome-phenotype, genotype-phenotype).     

The Reference Values of Hair Content of Trace Elements in Dairy Cows of Holstein Breed

Biological Trace Element Research - The objective of this study was to assess trace element content in hair of Holstein dairy cows bred in the Leningrad Region of Russia and to calculate the...     

Effects of Isoflavone-Enriched Feed on the Rumen Microbiota in Dairy Cows

In this study, we compared the effects of two diets containing different isoflavone concentrations on the isoflavone transfer from feed into milk and on the rumen microbiota in lactating dairy cows. The on-farm experiment was conducted on twelve lactating Czech Fleckvieh x Holstein cows divided into two groups, each with similar mean milk yield. Twice daily, cows were individually fed a diet based on maize silage, meadow hay and supplemental mixture. Control group (CTRL) received the basal diet while the experimental group (EXP) received the basal diet supplemented with 40% soybean isoflavone extract. The average daily isoflavone intake in the EXP group (16 g/day) was twice as high as that in the CTRL group (8.4 g/day, P<0.001). Total isoflavone concentrations in milk from the CTRL and EXP groups were 96.89 and 276.07 μg/L, respectively (P<0.001). Equol concentrations in milk increased from 77.78 μg/L in the CTRL group to 186.30 μg/L in the EXP group (P<0.001). The V3-4 region of bacterial 16S rRNA genes was used for metagenomic analysis of the rumen microbiome. The experimental cows exhibited fewer OTUs at a distance level of 0.03 compared to control cows (P<0.05) and reduced microbial richness compared to control cows based on the calculated Inverse Simpson and Shannon indices. Non-metric multidimensional scaling analysis showed that the major contributor to separation between the experimental and control groups were changes in the representation of bacteria belonging to the phyla Bacteroidetes, Proteobacteria, Firmicutes, and Planctomycetes. Surprisingly, a statistically significant positive correlation was found only between isoflavones and the phyla Burkholderiales (r = 0.65, P<0.05) and unclassified Betaproteobacteria (r = 0.58, P<0.05). Previous mouse and human studies of isoflavone effects on the composition of gastrointestinal microbial populations generally report similar findings.     

Iodine in Raw and Pasteurized Milk of Dairy Cows Fed Different Amounts of Potassium Iodide

Relation between iodine (I) intake by lactating Holstein cows and iodine concentrations in raw and pasteurized milk were investigated. Four treatment groups with eight cows assigned to each treatment were fed a basal diet containing 0.534 mg I/kg alone or supplemented with potassium iodide at 2.5, 5 or 7.5 mg/kg in 7-week period. Iodine concentrations in raw milk increased with each increase in dietary I from 162.2 ng/ml for basal diet to 534.5, 559.8 and 607.5 ng/ml when 2.5, 5 and 7.5 mg/kg was fed as potassium iodide (P < 0.05). This trend was found for blood plasma and urine iodine concentration. Iodine supplementation had no significant effect on thyroidal hormones. high-temperature short-time (HTST) pasteurization process reduced I concentration. The mean iodine content found in the milk prior to heating processing was 466.0 ± 205.0 ng/ml, whereas for the processed milk this level was 349.5 ± 172.8 ng/ml. It was concluded that iodine supplementation above of NRC recommendation (0.5 mg/kg diet DM) resulted in significant increases in iodine concentrations in milk, although the effect of heating in HTST pasteurization process on iodine concentration was not negligible.     

荷斯坦牛HSP70-1基因遗传多态性与乳腺炎抗性关系

以253头中国荷斯坦奶牛为研究对象, 检测HSP70-1基因的多态性, 并分析其多态性与中国荷斯坦牛体细胞评分(Somatic cell score, SCS)的相关性。首先以PCR-SSCP法寻找HSP70-1基因编码区的突变, 并通过测序确定突变的类型, 根据突变类型寻找合适的内切酶, 最终采用PCR-RFLP方法鉴定实验牛基因型; 然后分析基因多态性与中国荷斯坦牛SCS的相关性。结果表明HSP70-1基因的1 623 bp处产生G→A→C突变, 2 409 bp处产生G→A突变, 两位点都是沉默突变, 未引起氨基酸序列的改变; 经χ2 适合性检验, 中国荷斯坦牛在两个位点均未达到Hardy-Weinberg平衡状态; 同时, 群体基因座不同基因型与SCS相关分析的结果表明, 2409位点基因型与SCS相关性不显著(P>0.05), 1623位点基因型与SCS相关性显著(P<0.05), CC型SCS显著低于AG、GG型(P<0.05), CC基因型为乳腺炎抗性基因型。在中国荷斯坦奶牛群体中, HSP70-1基因CC基因型可作为改良奶牛乳腺炎抗性性状的分子遗传标记。     

Choline and Choline Metabolite Patterns and Associations in Blood and Milk during Lactation in Dairy Cows

Milk and dairy products are an important source of choline, a nutrient essential for human health. Infant formula derived from bovine milk contains a number of metabolic forms of choline, all contribute to the growth and development of the newborn. At present, little is known about the factors that influence the concentrations of choline metabolites in milk. The objectives of this study were to characterize and then evaluate associations for choline and its metabolites in blood and milk through the first 37 weeks of lactation in the dairy cow. Milk and blood samples from twelve Holstein cows were collected in early, mid and late lactation and analyzed for acetylcholine, free choline, betaine, glycerophosphocholine, lysophosphatidylcholine, phosphatidylcholine, phosphocholine and sphingomyelin using hydrophilic interaction liquid chromatography-tandem mass spectrometry, and quantified using stable isotope-labeled internal standards. Total choline concentration in plasma, which was almost entirely phosphatidylcholine, increased 10-times from early to late lactation (1305 to 13,535 µmol/L). In milk, phosphocholine was the main metabolite in early lactation (492 µmol/L), which is a similar concentration to that found in human milk, however, phosphocholine concentration decreased exponentially through lactation to 43 µmol/L in late lactation. In contrast, phosphatidylcholine was the main metabolite in mid and late lactation (188 µmol/L and 659 µmol/L, respectively), with the increase through lactation positively correlated with phosphatidylcholine in plasma (R ² = 0.78). Unlike previously reported with human milk we found no correlation between plasma free choline concentration and milk choline metabolites. The changes in pattern of phosphocholine and phosphatidylcholine in milk through lactation observed in the bovine suggests that it is possible to manufacture infant formula that more closely matches these metabolites profile in human milk.