【作者】 黄文明；

【导师】 李胜利； 曹志军；

【作者基本信息】 中国农业大学 ， 动物营养与饲料科学， 2014， 博士

【摘要】 本研究通过四个试验探究了围产前期日粮能量水平及日粮中添加丁酸钠和丙酸钙对奶牛干物质采食量(DMI)、泌乳性能、能量代谢、瘤胃适应性、免疫力和抗氧化力等方面的影响。试验一研究了围产前期日粮能量水平对奶牛DMI、泌乳性能和能量代谢的影响。采用随机区组试验设计,将39头经产荷斯坦奶牛分成3个处理组,在围产前期分别饲喂3种不同能量的日粮(6.8MJNEL/kg(100NRC组),6.2MJNEL/kg(90NRC组)、5.4MJNEL/kg(80NRC组))。3个处理组奶牛在产犊后到泌乳第70天都饲喂相同的日粮。围产前期奶牛的平均DMI和泌乳净能摄入量(NEI)随日粮能量水平的升高而显著升高(P<0.05),80NRC组奶牛在分娩前24h的DMI和NDF摄入量比100NRC组分别高26.1%和63.2%(P>0.05)。低能日粮显著提高了产后1～5周的DMI、NEI和NDF摄入量、1～10周的奶产量、1～3周的乳糖含量,显著降低了1～6周的乳脂含量(P<0.05)。100NRC、90NRC和80NRC组在产前的NEI分别占需要量的149.8%、126.2%和101.1%(P<0.05),在产后1～4周分别占需要量的72.7%、73.1%和75.2%(P>0.05)。低能日粮显著提高了围产前期奶牛血浆非酯化脂肪酸(NEFA)的浓度以及产后的血糖浓度,显著降低了产后NEFA和β-羟基丁酸浓度(P<0.05)：有提高产后第3天的肝脏丙酮酸羧化酶mRNA的表达丰度的趋势(P=0.08),显著降低了产后第3天的皮下脂肪组织激素敏感脂肪酶mRNA的表达丰度(P<0.05)。试验结果表明,围产前期饲喂低能日粮降低了奶牛产前的DMI变化幅度,提高了产后的DMI和奶产量,降低了体脂动员量,有利于缓解产后能量供需负平衡。试验二研究了围产前期日粮能量水平对奶牛瘤胃适应性的影响。14头带有永久性瘤胃瘘管的奶牛用于本试验,试验设计同试验一。低能日粮提高了奶牛产前的瘤胃液pH值,显著降低了产后的瘤胃液pH值(P<0.05)。在产后第7、8天的连续监测中,80NRC组奶牛有3个时间点的pH值低于5.6,而其他两个处理组都高于5.6。低能日粮显著降低了产前瘤胃液丙酸和丁酸浓度(P<0.05),提高了产后的挥发性脂肪酸(VFA)浓度(P<0.05),降低了产后的乙酸和丙酸比例(P<0.05)。100RNC组奶牛在产前7d的产琥珀酸丝状杆菌数量低于其他两组(P<0.05)。在产后第7天,80NRC组奶牛的产琥珀酸丝状杆菌数量显著高于其他两组,黄色瘤胃球菌数量显著高于100NRC组(P<0.05)。试验结果表明,产前饲喂低能日粮的奶牛在产后的瘤胃液VFA浓度更高,但更易受到亚急性瘤胃酸中毒的影响。试验三研究了围产前期日粮能量水平对母牛和初生犊牛免疫力和抗氧化力的影响。试验设计和试验奶牛同试验一。低能日粮显著提高了分娩当天和产后的血浆总抗氧化力(T-AOC)浓度和产后的IL-4浓度,显著降低了初乳IgG浓度(P<0.05),对血液IgG、丙二醛、谷胱甘肽过氧化物酶和超氧化物歧化酶浓度都没有显著影响(P>0.05)；对初生犊牛Oh和24h的免疫力和抗氧化力没有显著影响(P>0.05)试验四研究了在围产前期日粮中添加丁酸钠和丙酸钙对奶牛泌乳性能、能量代谢和瘤胃发酵参数的影响。采用随机区组试验设计,将45头经产荷斯坦奶牛分成3个处理组。3个处理组在整个试验期都饲喂与试验一80NRC组奶牛相同的基础日粮。分别在围产前期日粮中添加Og(对照组)、200g(1.5%添加组)和400g(3.0%添加组)添加剂(丁酸钠含量为25%,丙酸钙含量为5%,DM)。试验期从预产期前21d到产后28d。添加丁酸钠和丙酸钙显著提高了分娩当天的DMI(P<0.05),对产前和产后的DMI都没有显著影响(P>0.05)；显著提高了产前7d的瘤胃液总VFA和丁酸浓度及血糖浓度(P<0.05)；显著降低了产后的血浆NEFA浓度(P<0.05)。1.5%和3.0%添加组奶牛在产后1-4周的奶产量比对照组分别提高了1.21和1.07kg/d(P>0.05)。试验结果表明,添加丁酸钠和丙酸钙有利于提高奶牛DMI和泌乳性能,缓解产后能量供需负平衡。更多还原

【Abstract】 The objective of these experiments were to evaluate the effects of prepartum dietary energy density and dietary supplementation with sodium butyrate and calcium propionate on dry matter intake (DMI), lactation performance, energy metabolism, ruminal adaption, immunity and antioxidant capacity in multiparous Holstein cows.Part one was to determine the effects of reduced energy density of close-up diets on DMI, lactation performance and energy metabolism in multiparous Holstein cows. Thirty-nine dry cows were blocked and assigned randomly to three groups fed a high energy density diet [100NRC;6.8MJ of net energy for lactation (NEL)/kg], or a middle energy density diet (90NRC, n=13;6.2MJ NEL/kg), or a low energy density diet (80NRC, n=13;5.4MJ NEL/kg) from21day before expected day of calving. After parturition, all cows were fed the same lactation diet to70day in milk (DIM). The DMI and NEL intake prepartum were significantly decreased by the reduced energy density diets (P<0.05). The80NRC group consumed26.1%and63.2%more DMI and NDF, respectively, compared with100NRC group in the last24h before calving. The DMI, NEI and NDF intake of the first5wk of lactation, milk yield of the first10Wk of lactation and the milk lactose content of the first3wk of lactation were increased by the reduced energy density diet (P<0.05). The energy consumption for100NRC,90NRC and80NRC groups were149.8%,126.2%and101.1%of their calculated energy requirements prepartum(P<0.05), and72.7%,73.1%and75.2%during the first4wk postpartum, respectively. The reduced energy density diet increased the content of prepartum NEFA and postpartum glucose, decreased the postpartum NEFA and BHBA content (P<0.05). The hepatic PC mRNA abundance was improved (P=0.08), and the subcutaneous adipose HSL mRNA abundance was depressed (P<0.05) by the reduced energy density diet on3DIM. In conclusion, the prepartum reduced energy density diet was effective in controlling DMI change rate prepartum, and was beneficial in increasing DMI and milk yield, and decreasing the adipose tissue mobilization and alleviating negative energy balance postpartum.Part two was to evaluate the effects of reduced energy density of close-up diets on ruminal adaption in multiparous Holstein cows. Fourteen dairy cows were enrolled in the trail. The experimental design was same to part one. The ruminal pH of80NRC group was higher prepartum and lower during the first4wk of lactation compared with90NRC and100NRC groups (P<0.05).80NRC group had3sampling points of pH below5.6, which was determined at hourly intervals on7and8DIM, while there were not any for90NRC and100NRC groups. The reduced energy density diet depressed the average ruminal concentration of propionate and butyrate prepartum, and increased the concentration of volatile fatty acids (VFA), and decreased the ratio of acetate to propionate postpartum (P<0.05). The Fibrobacter succinogenes population for100RNC group was lower than that for90NRC and80NRC groups prepartum.80NRC group had higher population of Butyrivibrio fibrisolvens and Ruminococcus flavefaciens relative to100NRC and90NRC groups, and higher Megasphaera elsdenii population compared with100NRC group on7DIM. The results indicated that the cows fed reduced energy density diet prepartum had higher VFA concentration, but were more susceptible to subacute ruminal acidosis postpartum.Part three was to determine the effects of reduced energy density of close-up diets on immunity and antioxidant capacity in multiparous Holstein cows and newborn calves. The experimental design and cows were same to part one. The lower energy density diets increased the concentration of T-AOC and IL-4during the postpartum, and the concentration of T-AOC on the parturition day, and decreased the IgG concentration of colostrum (P<0.05). The immunity and antioxidant capacity of newborn calves at0h and24h were not affected by maternal energy intake during the close-up period.Part four was to estimate the effects of sodium butyrate and calcium propionate supplementation during close-up period on lactation performance, energy metabolism and ruminal fermentation in multiparous Holstein cows. Forty-five dairy cows were blocked and assigned randomly to1of3treatments. All the cows fed the same diet from-21d to28DIM which was same to the80NRC group diet of part one, and added0g/d (Control group),200g/d (1.5%group) and400g/d (3.0%group) sodium butyrate and calcium propionate to the3treatment diets during the close-up period, respectively. Sodium butyrate and calcium propionate supplementation increased the DMI on the parturition day(P<0.05), but had no effect on DMI prepertum and postpartum (P>0.05), improved the concentration of ruminal TVFA and acetate and blood glucose on-7d, and decreased NEFA concentration postpartum (P <0.05). The milk yields for1.5%and3.0%groups were1.21and1.07kg/d more than control group, respectively, during the first4wk of lactation(P>0.05). The results indicated that sodium butyrate and calcium propionate supplementation was beneficial in increasing DMI and milk yield, and alleviating negative energy balance during transition period.更多还原