A stochastic model simulating milk fever in a dairy herd

A simulation model was developed to evaluate the long-term effect of control strategies against milk fever (MF); here, we present the base model and sensitivity analyses. The representation of the within-herd dynamics was based on the existing SimHerd II model. Because of the relationships between MF and other diseases, the new model (called “SimHerd III”) includes diseases common in a dairy herd.

The cow level risk factors modelled were: base risk in the herd, parity, milk-yield potential, lactational disease recurrence, disease interrelationships, body condition and season. The diseases include clinical cases of MF, dystocia, downer-cow syndrome, retained placenta, metritis, displaced abomasum, ketosis and mastitis. The effects of diseases were represented by daily milk yield, daily body weight, daily feed intake, risk of stillbirth, conception probability, decision on culling, death and immediate removal. Simulated technical results showed that the herd effects of reduced risk of MF differed according to the reproductive efficiency in the herd. These interactions between reproduction efficiency and the effect of reduced base risk of MF were related to differences in how the simulated herds reacted to the reduction in replacements caused by MF.

In the sensitivity analysis, eight potential key parameters were changed to their lowest and highest expected values retrieved from the literature. When measuring the sensitivity on milk production in the herd (as the economically most important technical effect), the model seemed most sensitive to the uncertainty of effect of MF on death risk and MF-recurrence risk.     

中草药饲料添加剂对奶牛免疫机能影响的研究

为探讨中草药饲料添加剂对奶牛免疫水平的影响,选择健康奶牛20头作为试验对象,分试验组和对照组,各10头,连续给药7d,测定奶牛的Ea花环形成率、EAC花环形成率、淋巴细胞转化率、红细胞C3b受体花环形成率和IC花环形成率。试验结果显示,试验组奶牛和对照组相比,其免疫机能水平明显提高。     

优质高产奶牛高效全混合饲料配方筛选试验

中国荷斯坦奶牛60头饲喂4种不同紫花苜蓿干草配比、不同精粗比的日粮，以研究日粮配方对奶牛产奶量、乳脂率、经济收益的影响。试验结果说明，大比例紫花苜蓿干草日粮（紫花苜蓿占24％DM）乳脂率显著（P〈0．05）或极显著提高（P〈0．01）；日粮营养水平提高，产奶量提高（P〈0．05；P〈0．01）；最佳经济效益日粮为含大比例紫花苜蓿，营养水平较低的日粮（P〈0．01）；在大的精粗比例下，紫花苜蓿干草不是日粮成本的限制因素，而青贮饲料配比为日粮成本的限制因素。只有合理安排精粗比例，适当使用紫花苜蓿干草，可提高奶牛饲养经济效益。     

壳聚糖对奶牛血清胆固醇和蛋白质的影响

选择体重、胎次、泌乳期、产奶量相近、营养中等、临床健康、CMT检测呈阴性的中国荷斯坦奶牛40头,随机分为对照组和试验1、2、3组四个组。在基础日粮中分别添加壳聚糖0g/d、2g/d、4g/d、6g/d,连续饲喂5周。结果:试验1、2组血清胆固醇含量分别为2.75～3.07mmol/L、2.69～3.05mmol/L(P>0.05);试验3组牛在0～2周分别为2.75～3.03mmol/L(P>0.05),3～5周分别为2.31±0.62(mmol/L)、2.15±0.51(mmol/L)和2.06±0.49(mmol/L);分别降低了21.24%、21.82%和28.96%,差异显著(P<0.05)。血清总蛋白、白蛋白和球蛋白含量各组均无显著性差异(P>0.05)。结论:应用6g/d壳聚糖能够降低泌乳奶牛血清胆固醇的含量,但不影响奶牛血清蛋白质的含量。壳聚糖可以作为饲料添加剂在牛群中长期使用。     

天然沸石在肉牛饲养上的应用研究

本次试验用１６头月龄、体重相似的利×延杂种一代母牛，随机分成四组，即试Ⅰ、试Ⅱ、试Ⅲ和对照组。分别加入２．５％、５．０％、７．５％的天然沸石粉（基础日粮相同），经过６０天的饲养试验，其日增重分别为１．０ｋｇ、１．２３ｋｇ、１．０４ｋｇ、０．９１ｋｇ，比对照组提高９．９％、３５．１６％、１４．２９％，差异显著（Ｐ＜０．０５）。经过１０ｄ的消化试验，结果表明：添加沸石使粗蛋白消化率分别提高５．０９％、８．１２％、６．０７％，差异显著（Ｐ＜０．０５），使粗纤维的消化率提高３．９７％、５．８９％、４．９０％，差异显著（Ｐ＜０．０５）。添加沸石可降低瘤内氨氮浓度，调节酸碱平衡，降低血液中的ＮＰＮ、ＢＵＮ含量，增加ＧＯＴ、ＧＰＴ酶的活性．     

奶牛初乳防治胎衣不下的效果

126头中国荷斯坦奶牛分娩后3～6h颈部两侧皮下注射健康奶牛初乳各25ml,研究初乳防治奶牛RFM的效果。结果表明,试验组126头奶牛的RFM发病率为6.35%,显著低于对照组(P<0.05);试验组71头经产牛RFM发病率为11.27%,显著低于对照组(P<0.05),而试验组55头初产牛RFM发病率与对照组差异不显著(P>0.05)。利用奶牛初乳防治RFM的效果显著,经产牛的效果优于初产牛。     

产后奶牛子宫内膜炎神经肽（SP、VIP）对子宫免疫调节的研究

本试验研究了急性产后子宫内膜炎神经肽（SP、VIP）变化,以探讨子宫内膜炎神经肽对子宫局部免疫的影响。对10头产后急性化脓性子宫内膜炎患牛进行子宫内膜及血清SP、VIP含量的检测,并选择10头产）06-8d健康的奶牛为对照组。结果表明,产后急性子宫内膜炎患牛子宫内膜及血清中SP含量显著升高,试验组与对照组差异极显著（P〈0．01）,而VIP含量显著降低,试验组与对照组差异极显著（P〈0．01）。急性产后子宫内膜炎属于局部炎症,其发生与神经肽（SP、VIP）浓度密切相关,sP含量的升高和VIP含量的降低对机体的免疫起调节作用。     

Genetic and Environmental Correlations Among Female Fertility Traits,and Between the Ability to Show Oestrus and Milk Production in Dairy Cattle

Genetic and environmental correlations were estimated both between the ability to show oestrus and milk production, and among different fertility traits (heat-intensity score, number of days between consecutive inseminations, number of inseminations per service period, interval between calving and first or last insemination, and interval between first and last insemination). Milk production was measured as the average of the energy-corrected milk yield on second and third monthly test days. The number of records were approximately 450000, 350000, 180000 and 75000 in the heifer period, first, second and third lactations, respectively. A linear, trivariate model that included the effects of herd-year, year, month, age and cow's sire was applied. The results indicated that further selection for increased milk production is not expected to deteriorate heat intensity. The number of days between calving and first insemination, the number of inseminations and the heat intensity were complementary, and can be recommended for a selection index for fertility.     

Competition for Total Mixed Diets Fed Restrictively Using One or Four Cows per Feeding Station

A study was made of feed intake, behaviour and production in 16 dairy cows with one and four cows per feeding station (treatment 1c and 4c, respectively) with a restricted amount of a total mixed diet. The computerized feeding stations comprised continuously weighed feed-troughs placed at feeding gates. The cows were divided in two groups and were studied in a change-over experiment in which each group was submitted to each treatment twice. Video recordings and the computerized feeding system were used to collect data on the order of social dominance, aggression levels, time budgets and the consumption of feed and water. The effects of individual dominance value (DV), age, eating rate and energy requirements were recorded on ingestive behaviour. The cows on treatment 4c visited the feeding stations more often (106% more visits and 76% more meals) and shortened their feeding times by 50%, resulting in higher consumption rates compared with treatment 1c. In addition, aggression increased, resulting in a greater number of displacements at feeding. It is concluded that the investigated combination of competition for feeding space and restricted amounts of feed cannot be recommended.     

隐性乳房炎奶牛4个微卫星座位的遗传变异分 析

选择牛23号染色体上4个微卫星标记BM1818、BM1443、BM1258 和BM1905,用非变性聚丙酰胺凝胶电泳方法对石河子某奶牛场150头进口荷斯坦奶牛进行了遗传变异的检测分析并计算相应的遗传指标,利用SPSS12.0 软件分析了四个微卫星座位与进口荷斯坦牛隐性乳房炎的关系,探讨各自座位上不同基因型与奶牛隐性乳房炎之间的相互关系。