Regression tree analysis of the relationship between the concentrations of antimicrobial components and the microbiota of normal milk from dairy cows

The purpose of this study was to determine the concentrations of antimicrobial components (immunoglobulin A (IgA), lactoferrin (LF), lingual antimicrobial peptide (LAP), and S100A7) in normal milk and their relation to host factors (Age, somatic cell count (SCC), days in milk, richness, and alpha diversity of the milk microbiota) in dairy cows using multivariate regression tree analyses, and to clarify how the milk microbiota is related to the obtained results. Thirty normal milk samples were collected from a commercial dairy farm in June 2020. The thresholds that predicted the concentration of each antimicrobial component in milk were obtained by regression tree analysis, and the beta-diversity of the milk microbiota composition between groups divided according to each threshold was compared by an analysis of similarities test. The IgA and LF concentrations were mainly predicted by the SCC (177,500 and 70,000 cells/ml, respectively), and the LAP and S100A7 concentrations were predicted by Age (29.667 and 40.3 months, respectively). No relationship was observed between the concentration of IgA, LAP, or S100A7 and the milk microbiota composition between the groups divided by the threshold for prediction, but the milk microbiota composition was significantly different between the groups divided by the threshold for predicting the LF concentration. Our results indicated that the LF concentration in normal milk may be associated with the milk microbiota composition.     

不同粗饲料对奶牛乳产量和乳成分的影响

选择18头荷斯坦奶牛,设置3个处理,每个处理6个重复,每个重复1头奶牛,研究不同粗饲料对奶牛泌乳性能和乳成分的影响,3个处理的粗饲料分别为玉米秸(Ⅰ组)、玉米秸+青贮玉米秸(Ⅱ组)、羊草(Ⅲ组)。试验结果表明:①试验Ⅱ组与试验Ⅲ组平均产奶量差异不显著(P>0.05),试验全期分别比Ⅰ组提高了8.82%(P<0.05)和9.57%(P<0.05);②不同处理间的乳糖、乳脂含量差异不显著(P>0.05);对于乳蛋白,在试验40d时3个试验组差异不显著(P>0.05),在第15d时Ⅱ组、Ⅲ组分别比Ⅰ组降低了7.43%(P<0.05)和8.57%(P<0.05)。对于乳干物质,Ⅱ组与Ⅲ组差异不显著(P>0.05)。根据上述生产性能指标综合评定,玉米秸+青贮玉米秸可有效替代羊草饲喂奶牛,而不降低泌乳性能。     

复合益生菌制剂对奶牛泌乳性能及乳品质的影响

为研究复合益生菌制剂对奶牛泌乳性能及乳品质的影响,试验选取45头泌乳期相近的荷斯坦奶牛,随机分为3组,对照组、试验1组、试验2组,每组3个重复,每个重复5头。对照组饲喂基础日粮,试验1、2组分别在基础日粮中添加1%、2%的复合益生菌制剂,试验期为60d。结果表明:试验2组在第10、30、60天奶牛产奶量较对照组分别提高2.28%、0.62%、9.08%(P<0.05),试验1组在第10、60天较对照组分别提高4.6%、8.9%(P<0.05);第30天时,试验1、2组乳中总固形物含量较对照组均显著性提高(P<0.05),乳糖率、乳蛋白率、乳脂率之间差异不显著(P>0.05);第60天时,与对照组相比,试验1、2组乳中乳糖率分别提高了4.41%、7.02%(P<0.05),乳蛋白率提高了4.16%、9.97%(P<0.05),总固形物含量提高了2.44%、3.02%(P<0.05),乳脂率含量之间差异不显著(P>0.05)。综上,日粮中添加复合益生菌制剂可有效提高奶牛产奶量及乳品质,且添加2%复方益生菌制剂效果更优。     

植物甾醇对泌乳前期奶牛产奶量及乳成分的影响

根据年龄、胎次、泌乳时间和产奶量选择24头泌乳奶牛,随机分为对照组、试验Ⅰ组和试验Ⅱ组。对照组饲喂奶牛场配制的全混合饲料,试验Ⅰ和Ⅱ组每头奶牛日粮中分别添加40 g/d和80 g/d植物甾醇,研究植物甾醇对奶牛生产性能的影响。结果表明,与对照组相比,试验Ⅰ和Ⅱ组奶牛的产奶量分别提高了2.07 kg/d(5.64%,P0.05)和1.74 kg/d(4.75%,P0.05);试验Ⅰ和Ⅱ组奶牛乳脂率分别提高了8.22%(P0.01)和2.97%(P0.05);乳蛋白率分别提高了2.45%(P0.05)和1.05%(P0.05);非脂固形物分别提高了1.29%(P0.05)和0.23%(P0.05),体细胞数分别下降了37.31%和19.34%,但差异均不显著(P0.05);牛奶中乳尿素氮含量分别降低了5.29%(P0.05)和7.58%(P0.01)。结果表明泌乳前期奶牛补饲一定量的植物甾醇能够提高产奶量和改善乳成分。     

中草药制剂对热应激奶牛泌乳性能、抗氧化能力及免疫功能的影响

为探讨复合中草药制剂对热应激奶牛泌乳性能、抗氧化能力及免疫功能的影响,选择产奶中后期的健康中国荷斯坦奶牛20头,按泌乳时间和产奶量相近的原则均分为A、B、C和D 4组。A组为对照组,饲喂基础日粮;B、C和D组分别在每头牛的基础日粮中添加50,100和150 g/d水平的复合中草药制剂。每天测定产奶量,在试验的第1(添加复合中草药制剂之前)、20和40天逐头采集血样,测定不同剂量复合中草药制剂对热应激奶牛血淋巴细胞凋亡率、血液抗氧化酶GSH-Px、CAT基因及血淋巴细胞凋亡相关基因Bcl-2、p53表达水平的影响。结果表明,B、C和D组的日产奶量较对照组分别提高了20.26%(P<0.05),24.20%(P<0.05)和16.98%(P>0.05);乳中体细胞数较对照组分别降低了21.68%(P<0.05),29.88%(P<0.05)和24.22%(P<0.05);奶牛血液抗氧化酶GSH-Px、CAT基因的表达水平分别比对照组提高了5.00%(P>0.05),13.00%(P<0.05),6.00%(P>0.05)和5.00%(P>0.05),16.00%(P<0.05),3.00%(P>0.05);奶牛血淋巴细胞平均凋亡率分别比A组降低了18.20%(P>0.05),17.86%(P>0.05)和12.51%(P>0.05);奶牛血淋巴细胞Bcl-2在20,40 d时均极显著高于A组,全期的平均水平分别比对照组高出105.00%(P>0.05),113.00%(P>0.05)和57.00%(P>0.05);p53基因的表达水平在20,40 d时均极显著低于A组,全期的平均水平分别比对照组降低了24.00%(P>0.05),28.00%(P>0.05)和20.00%(P>0.05)。试验组中,C组奶牛的日产奶量、体细胞数、血液抗氧化酶活性、淋巴细胞凋亡相关基因表达等指标要优于B、D组;而血液淋巴细胞凋亡率指标为B组最好。说明复合中草药制剂能有效改善热应激奶牛的泌乳性能、抗氧化能力及免疫功能,且在本试验条件下,每头牛日粮中添加100 g/d水平的效果要优于50及150 g/d水平。     

饲料中添加烟酸对夏季奶牛产奶性能的影响

试验选取9头泌乳早期处于热应激的荷斯坦牛,采用3×3拉丁方设计,分别饲喂基础日粮(对照组)和在基础日粮中添加5g/d和10g/d烟酸日粮,研究添加烟酸对奶牛生产性能影响。结果表明:添加5g/d和10g/d烟酸可使奶牛产奶量分别提高13.20%和9.39%(P<0.05);而4%标准乳量无显著差异(P>0.05);添加烟酸对乳蛋白和乳脂率无显著影响(P>0.05)。     

过瘤胃赖氨酸对奶牛产乳量及乳成分的影响

试验采用随机分组试验设计,选择健康的中国荷斯坦奶牛48头,按照胎次、产奶量、泌乳日期一致原则,均匀分成4组,试验各组基础日粮相同,就饲粮中添加过瘤胃赖氨酸(Lys)对乳牛产乳量及乳成分的影响进行研究。4个处理组分别为:对照组(0添加组)不添加过瘤胃赖氨酸(RPLys)和试验Ⅰ组添加10 g(/头.d)、试验Ⅱ组添加20 g(/头.d)和试验Ⅲ组添加30 g(/头.d)。试验结果显示:经过饲喂后,试验各组与对照组相比,产奶量显著提高;试验Ⅲ组和试验Ⅱ组都与对照组差异显著(P0.05),其中试验Ⅲ组与对照组差异极显著(P0.01);乳蛋白含量有所提高,其中试验Ⅲ组与对照组有显著差异(P0.05);其他乳成分指标略有提高,但差异不显著(P0.05)。     

全混合日粮对奶牛产乳性能的影响

试验选用了12头奶牛,根据产奶量、泌乳天数和胎次相近的原则分为试验组和对照组,研究全混合日粮对奶牛产乳性能的影响。试验结果表明,试验组4％标准乳产量比对照组提高1 24kg,差异显著(P<0．05),乳脂率及乳脂、乳糖和乳固形物含量也分别比对照组显著提高11．60％、17．50％、13．21％和9．86％(P<0.05)。     

不同水平复合益生菌制剂添加对奶牛生产性能、乳品质及体细胞数量的影响

为分析不同水平复合益生菌制剂添加对奶牛生产性能、乳品质及体细胞数量的影响,试验选择胎次、产奶量、泌乳天数相近的荷斯坦奶牛160头随机分成4个组,每个组4个重复,每个重复10头,1组饲喂基础日粮为对照组,试验2、3、4组每头奶牛分别在基础日粮中添加20、40、60 g/d复合益生菌制剂,预试验7 d,试验期为60 d。结果表明:(1)试验后的30、60 d,试验3、4组的平均产奶量较1相比分别提高16.0%、14.9%、25.6%、24.1%(P<0.05);(2)试验2、3、4组的4%乳脂校正、乳蛋白率、总固形物均高于1组(P>0.05);试验2、3、4组的尿素氮均低于1组(P>0.05);试验3、4组的乳糖率、乳脂率较1组分别提高14.6%、13.4%、5.0%、4.2%(P<0.05);(3)试验后的60 d,试验3、4组乳中体细胞数量较1组相比降低9.3%、7.1%(P<0.05)。综上,每头牛每天添加40 g复合益生菌制剂可以提高奶牛的生产性能、乳品质,减少体细胞数量。     

过瘤胃氨基酸高能复合物对奶牛产奶量及乳成分的影响

为研究不同过瘤胃氨基酸高能复合物对奶牛产奶量及乳成分的影响,试验选择胎次(3～5胎)、产奶量、产犊日期相近,体重(600±20)kg健康荷斯坦泌乳高峰期奶牛24头,随机分为4组,每组6头。1组为对照组,饲喂牛场常规日粮;2、3、4组为试验组,分别在常规日粮基础上添加过瘤胃氨基酸高能复合物Ⅰ、Ⅱ、Ⅲ500 g/(d.头)。正式期60 d。结果表明:奶牛日粮中添加过瘤胃氨基酸高能复合物后,均可明显提高奶牛产奶量、乳脂率、乳蛋白率及乳中总干物质含量。尤其是复合物Ⅲ,添加效果最为理想,平均日产奶量、乳脂率、乳蛋白率及总干物质含量分别比对照组提高21.19%(P<0.05)、21.31%(P<0.05)、9.72%(P<0.05)和10.34%(P<0.05),平均日校正乳产量提高35.70%(P<0.05)。     

Effect of linseed oil supplementation on performance and milk fatty acid composition in dairy cows

Thirty‐six Holstein‐Friesian crossbred lactating dairy cows were used to determine the effects of linseed oil supplementation on performance and milk fatty acid (FA) profile. Three treatments were as follows: basal diet (56:44 Roughage:concentrate [R:C] ratio, dry matter basis) supplemented with 500 g of palm oil as control (PO), 500 g mixture (1:1, w/w) of palm oil and linseed oil (POLSO) and 500 g of linseed oil (LSO). The LSO supplementation had no effects on total dry matter intake (DMI), milk yield and milk composition. Compared to control cows, cows supplemented with LSO increased milk concentrations of cis‐9,trans‐11 conjugated linoleic acid (CLA) and n‐3 FA (P < 0.05), particularly C18:3n‐3, C20:5n‐3 and C22:6n‐3. Feeding LSO reduced concentrations of milk short‐ and medium‐chain saturated fatty acids (P < 0.05) while it increased concentration of milk unsaturated fatty acids (P < 0.05). Milk proportions of n‐3 FA increased, whereas n‐6/n‐3 ratio decreased in the LSO as compared with the control (P < 0.05). In conclusion, supplementing dairy cows' diet based on corn silage with LSO at 500 g/day could improve the nutritional value of milk with potential health‐beneficial FA without detrimental effect on milk composition or cow's performance.     

Effects of increasing days of exposure to prepartum transition diets on milk production and milk composition in dairy cows

Objective To evaluate the effects of length of exposure to prepartum transition diets on milk yield, fat and protein production. Design Prospective cohort study. The number of days that the cows were fed the prepartum transition diets was the exposure of interest. Procedures Holstein and Holstein x Jersey cows (n = 1008) were enrolled. Diets given in the far-off dry period (from end of lactation until approximately 3 weeks before expected parturition) consisted of ad libitum access to perennial ryegrass pastures. Prepartum transition diets included perennial ryegrass pasture, ryegrass silage, cereal hay, grain, grain by-product, protein meals, BioChlor(R), sodium monensin, virginiamycin or tylosin, MgSO(4), trace elements and vitamins. On a dry matter basis, these contained 16.0% crude protein, 4.2% rumen undegradable protein, and 9.9 mJ metabolisable energy/kg. Diets provided an estimated metabolisable protein balance of 286 g/day and dietary cation anion difference of -150 meq/kg dry matter. Statistical models controlled for effects of herd, calving day, breed, age and gestation period. Results Increasing length of exposure to the prepartum transition diets significantly increased the 4.0% fat- and 3.2% protein-corrected milk yield and milk-protein yield as a linear and quadratic effect. The optimal duration of exposure to the prepartum transition diets was 25 days for fat- and protein-corrected milk production and 22 days for milk protein production. Milk-fat percentage decreased significantly and linearly with increasing exposure to the prepartum transition diets; however, milk-fat yield or milk-protein percentage did not vary significantly with duration of exposure to the diets. Conclusions Increasing exposure to prepartum transition diets increased milk and milk-protein yields and decreased the milk fat-percentage, but not the milk-protein percentage or milk-fat yield. Aust Vet J 2008;86:341-351.     

高产奶牛乳量和乳成分的营养调控

本文从增加干物质的采食量。日粮成分的来源、环境控制、饲养方式等几方面的互作与协同加以剖析，阐述了在生产中如何提高奶牛的乳量和乳成分的饲养措施。     

Comparison between stearoyl‐CoA desaturase expression in milk somatic cells and in mammary tissue of lactating dairy cows

Stearoyl‐CoA desaturase (SCD) is an important enzyme in the bovine mammary gland, where it inserts a cis‐double bond at the Δ9 position in a wide range of fatty acids. Investigating SCD expression in the bovine mammary gland generally requires invasive biopsy to obtain mammary tissue. The aim of this study was to evaluate the use of milk somatic cells as a non‐invasive alternative to biopsy for measuring mammary SCD expression in dairy cows. Both milk somatic cells and mammary tissue were collected from 14 Holstein‐Friesian cows and used for analysis of SCD expression by real‐time PCR. The SCD5 mRNA levels in mammary tissue compared with SCD1 were low, and for several milk somatic cell samples, SCD5 expression was even below the limit of detection. A significant relationship was found between SCD1 expression in milk somatic cells and in mammary tissue. In addition, SCD1 expression in milk somatic cells was significantly related to Δ9‐desaturase indices in milk, which are commonly used as an indicator of SCD1 activity within the mammary gland. Our study showed that milk somatic cells can be used as a source of mRNA to study SCD1 expression in dairy cows, offering a non‐invasive alternative to mammary tissue samples obtained by biopsy.     

Relationship between fat accumulation in the liver and energy intake, milk fat yield and blood metabolites in dairy cows

In the present study, 42 multiparous Holstein cows were used to investigate the relationship between fat accumulation in the liver and dry matter intake, milk yield and blood metabolites. Based on the percentage of fat in the liver cell at 2 weeks post‐parturition, the cows were classified into three groups. These groups were: (i) less than 10% of fat (normal group, n = 29); (ii) 10–20% of fat (mild group, n = 6); and (iii) more than 20% of fat (moderate group, n = 7). The bodyweight of the moderate group was high (771 kg) before calving. The sufficiency rates of total digestible nutrients (TDN) were remarkably decreased (approximately 65%) in early lactation. The milk fat yield and milk fat composition of the moderate group were higher (P < 0.05) than the other groups at 1 and 2 weeks post‐parturition. It was suggested that non‐esterified fatty acids (NEFA) mobilized from adipose tissues was directly used by the mammary gland for synthesis of milk fat. The percentage of bromsulfalein (BSP) retention of the moderate group was high (21.1%) at 30 min, and it showed that the BSP clearance function was significantly decreased. The concentrations of NEFA, β‐hydroxybutyric acid and glucose were appropriate indicators of energy status; however, aspartate aminotransferase, γ‐glutamyl transpeptidase and total bilirubin were not sensitive indicators of a moderate fatty liver. Thus, high‐yielding cows that calve in an overweight condition are more likely to develop excessive fat accumulation in the liver because of great mobilization from adipose tissues post‐parturition. In cows with a moderately fatty liver, a decrease in TDN sufficiency rates, an increase of milk fat yield and a reduction of liver function were observed in early lactation. The increase of serum NEFA and milk fat composition resulting from mobilization of adipose tissues helped to diagnose moderate fatty liver.     

饲喂复合益生菌对泌乳中期奶牛产奶量及乳成分的影响

本文旨在研究不同剂量的复合益生菌制剂对泌乳中期奶牛产奶量及乳成分的影响。试验选用18头体重、胎次、产奶量均相近的中国荷斯坦奶牛,采用完全随机设计,分为3个处理组,即(对照组)、0.6×1011 cfu/d(试验1组)与1.2×1011 cfu/d(试验2组),试验期70 d(预试期10 d,正试期60 d)。结果表明:试验1组、2组与对照组相比产奶量分别提高3.11%、4.80%,4%乳脂校正乳提高5.14%、8.07%,能量校正乳提高4.74%、8.76%,差异均显著(P<0.05);试验2组较对照组乳脂率和乳蛋白率分别提高5.56%、5.86%,并显著提高乳脂、乳蛋白、非脂乳固体物的产量(P<0.05)。两试验组牛奶中的乳糖率及乳糖产量与对照组无显著差异(P>0.05)。这表明,日粮中饲喂复合益生菌可以显著提高奶牛生产性能,从而提高饲料利用效率。     

微量元素添加剂对奶牛泌乳性能影响

针对奶牛日粮营养不平衡,导致产奶量低、乳脂率低,经济效益低的生产状况,本试验随机选择4胎、5胎、6胎泌乳期牛10头,分试验组与对照组,各试验牛按日产奶量饲喂不等量精料补充料、玉米秸与稻秸按2:1混合的粗饲料、尿素基础饲粮。试验组饲粮按产奶量分等添加微量元素添加剂,试验期试验组奶料比为3.25,对照组为2.9,试验组增加0.34kg(P<0.05)。试验期产奶量按4.0%标准乳计算,试验组日产奶量高于对照组4.31kg(P<0.05)。按每kg增重折合鲜奶8.0kg校正体重后标准乳计算,试验组日产奶量高于对组4.36kg(P<0.01)。乳脂、乳钙、乳蛋白质(2.29 乳脂率×0.33计算),试验组比对照组分别提高0.32%、0.10%、0.03%(P<0.05)。添加微量元素的试验组,头均日产标准奶24.12kg,对照组19.8kg(P<0.05),按kg鲜奶1.80元计算,头、日产奶分别收入43.42元、35.62元(P<0.05)。头均日耗饲料的实际价格试验组9.15元、对照组7.82元(P<0.01),试验组比对组多增收6.46元(P<0.05),经济效益显著。     

Effect of monensin and vitamin E on milk production and composition of lactating dairy cows

Feeding unsaturated oils to lactating dairy cows impair ruminal biohydrogenation (BH) of unsaturated fatty acids (USFA) and increase ruminal outflow of BH intermediates such as trans‐10, cis‐12 CLA that are considered to be potent inhibitors of milk fat synthesis. Supplementing lactating dairy cow’s rations containing plant origin oils with monensin and/or vitamin E may minimise the formation of trans‐10 isomers in the rumen, thereby preventing milk fat depression. Therefore, this study was conducted to evaluate the effects of monensin and vitamin E supplementation in the diets of lactating dairy cows containing whole cottonseed, as the main source of FA on feed intake, milk production and composition, milk fatty acid profile, efficiency of nitrogen (N) utilisation, efficiency of net energy (NE) utilisation and nutrients digestibilities. Four multiparous Holstein lactating dairy cows (86 ± 41 days in milk) were assigned to a balanced 4 × 4 Latin square design. Each experimental period lasted 21 days with a 14 days of treatment adaptation and a 7 days of data collection. The control diet was a total mixed ration (TMR) consisted of 430 g/kg forage and 570 g/kg of a concentrate mixture on dry matter (DM) basis. Cows were randomly assigned to one of the four dietary treatments including control diet (C), control diet supplemented with 150 mg of vitamin E/kg of DM (E), control diet supplemented with 24 mg of monensin/kg of DM (M) and control diet supplemented with 150 mg of vitamin E and 24 mg of monensin/kg of DM (EM). Dry matter intake (DMI) ranged from 19.1 to 19.5 kg/d and was similar among the dietary treatments. Dietary supplementation with vitamin E or monensin had no effect on milk production, milk fat, protein and lactose concentrations, efficiency of utilisation of nitrogen and net energy for lactation (NE_L). Digestibility of DM, organic matter (OM), crude protein (CP) and ether extract (EE) was not affected by the dietary treatments. Digestibility of neutral detergent fibre (NDF) was higher in cows fed with the M and EM diets in relation to those fed the C and E diets. The concentrations of C4:0, C6:0, C8:0, C10:0, C12:0, C14:0, C15:0, trans‐10‐16:1, cis‐9‐16:1, 17:0, 18:0, trans‐11‐18:1, cis‐9‐18:1, cis‐9, trans‐11 conjugated linoleic acid (CLA), trans‐10, cis‐12 CLA, and 18:3n‐3 FA in milk fat were not affected by the dietary supplementations. While feeding the M diet tended to decrease milk fat concentration of C16:0, the milk fat concentration of C18:2n‐6 FA tended to be increased. Dietary supplementation with vitamin E or monensin had no effect on milk fat concentrations of saturated, unsaturated, monounsaturated, polyunsaturated, short chain and long chain FA, but feeding the M diet numerically decreased milk fat concentration of medium chain fatty acids (MCFA). The results showed that vitamin E and/or monensin supplementations did not improve milk fat content and did not minimise the formation of trans‐10 FA isomers in the rumen when whole cottonseed was included in the diet as the main source of fatty acids.