【作者】 王长宏；

【导师】 吕文发；

【作者基本信息】 吉林农业大学 ， 动物遗传育种与繁殖， 2007， 硕士

【摘要】 本试验旨在研究蛋氨酸锌对奶牛泌乳性能及繁殖性能的影响，并筛选出奶牛日粮中适宜的蛋氨酸锌添加剂量。选取泌乳量、体重差异不显著，胎次2-3胎，平均在预产期前40-50天，且健康无疾病的经产奶牛60头。奶牛随机分成4组，每组15头，供试验用。各组奶牛均饲喂含锌量37.15mg／kg（以干物质计量）的基础日粮，其中，A组=基础日粮（对照组）；B组=基础日粮+120mg／kg蛋氨酸锌；C组=基础日粮+240mg／kg蛋氨酸锌；D组=基础日粮+360mg／kg蛋氨酸锌，预试期为10天。试验方法及所测指标如下：于产后第七天到第十四天记录日产奶量，最后计算每组平均日产奶量；每组随机抽取分娩后第七天、第十四天的奶样，测定乳糖、乳蛋白、乳脂、乳锌含量及乳体细胞数；于产后第七天，随机采取奶牛血样，测定血清中PRL含量；于发情周期的当天和第12天，随机采取血样，测定血清中雌二醇（Estradiol，E2）和孕酮（Progesterone，P）的浓度；记录奶牛的分娩情况、犊牛初生重、产后第一次发情日期、产后发情周期，并采用人工授精技术进行受精，记录第一情期受胎率，最后取平均值，作为衡量奶牛繁殖性能的指标。试验结果如下：对泌乳性能的影响：B、C、D组日均产奶量依次为23.65kg／d、23.67kg／d、23.72kg／d，较对照组（22.41kg／d）分别提高了5.53％、5.85％、5.58％，且差异显著（P＜0.05）。试验组间差异不显著（P＞0.05），添加360mg／kg蛋氨酸锌组日均产奶量比添加240mg／kg组日均产奶量低0.05kg／d，说明产奶量并不是随着蛋氨酸锌添加量的增加而增加的；随着日粮添加蛋氨酸锌水平的增加，试验组乳脂、乳蛋白、乳糖含量较对照组均有不同程度的增加，但差异不显著（P＞0.05）；随蛋氨酸锌水平的升高，乳锌含量较对照组显著增加，但增加的幅度逐渐减小。试验组B与C、D两组差异显著（P＜0.05），C、D两组间差异不显著（P＞0.05）；B、C、D组的乳体细胞数较对照组显著降低，且B组与C、D两组间也表现出显著差异。随蛋氨酸锌添加量的增加，乳体细胞数降低幅度逐渐减小。对繁殖性能的影响：添加蛋氨酸锌组的正常分娩率为80％、93.33％、93.33％，较对照组（73.33％）有一定程度的改善；试验组犊牛初生重与对照组犊牛初生重差异不显著（P＞0.05），但数据结果显示，日粮添加蛋氨酸锌有使犊牛初生重增加的趋势；日粮添加蛋氨酸锌可使奶牛产后发情提前，且差异显著（P＜0.05），其中，添加蛋氨酸锌240mg／kg组提前的幅度较大，提前了5.8d；试验组发情周期与对照组差异不显著（P＞0.05），均在正常范围之内；B、C、D组血清促乳素含量均比对照组高，且差异显著（P＜0.05），依次增加1.46ng／ml、3.08ng／ml、3.45ng／ml，试验组B与C、D两组间也达到显著差异（P＜0.05）。血清促乳素含量随蛋氨酸锌添加量的增加而增加，但增加的幅度逐渐减小；日粮添加蛋氨酸锌组，与对照组相比，在奶牛发情周期的发情期和黄体期，均可使奶牛血清中E₂、P₄含量增加，在发情期，E₂血清含量增加明显，在黄体期P₄增加明显，但差异不显著（P＞0.05）；添加蛋氨酸锌试验组，与对照组相比，第一情期受胎率得到了提高，依次提高了6.66％、20.00％、20.00％。试验研究结果表明，在日粮中添加蛋氨酸锌，对奶牛的泌乳性能及繁殖性能有一定的促进作用。对各项指标所测得的数据进行统计分析，综合评定认为，在含锌37.15mg／kg（以干物质计量）的基础日粮中，添加240mg／kg蛋氨酸锌为宜，可作为奶牛日粮中锌添加量的参考数据。更多还原

【Abstract】 The objections of this study are to determine the effects of the different levels of Zinc-Methionine（Zn-met） supplemented on on lactational performance and reproductive performance in dairy cows,and find out the suitable does.Sixty multiparity（parity 2or3）,healthy dairy cows,which had the adjacent milk yield and body weight,and at 40-50 mean days in preterm.Cows were randomly assigned to four groups（A,B,CD）,fifteen cows of each group.Groups were feeded with routine dietary（Zn37.15mg/kgDM）,among which,group A was used to as the control group（routine dietary） andB,C,D groups were added 120mg/kg,240mg/kg,360mg/kg Zn-Met in routine dietary. Pretesting date was 10 days.The testing methods and targets were shown as below:Recorded milk weights from the 7th day postpartum to 15th day postpartum,and calculate the average day-milk yield;Milk samples were draw in 7th day and 14th day postpartum,and testing the milk fat,milk lactose,milk protein,milk Zn and the milk somatic cell counts（SCC）;Blood samples were adopted at the 7th day postpartum,testing the levels of serum PRL; Blood samples adopted at the 1st day and the 12th day（oestrus and luteal phase） in oestrous cycle were used to test the levels of E₂ and P₄ in serum;In the experimental stage, registering the condition of parturition, the mean birth weight of calves,the first oestrus,the oestrus scycle postpartum and the conception rate of the first service after artificial insemination.The above targets were all took general average as indexes judging the reproductive performance of dairy cows.The results as follow:Effects on lactational performance:The milk yields of the B,C,D groups were 23.65kg/d、23.67kg/d、23.72kg/d,respectively,were 5.53%、5.85%、5.58% significantly higher than A group（22.41kg/d）（P<0.05）, but no significant difference（P>0.05） among the B,C,D groups,furthermore, D group was 0.05 kg/d lower than the C group;With the augment of the levels of supplemented Zn-Met.the milk fat, milk lactose,milk protein of treatment groups increased in different extent than the control group,but no significant difference（P>0.05）; With the augment of the levels of supplemented Zn-Met,the content of milk Zn increased significantly（P<0.05）,but the increasing extent went down gradually.Group C,D were significantly different from group B（P<0.05）,but there was no significant difference between group C and D;Th.e milk somatic cell counts（SCC） of group B.C and D decreased significantly than the control group.But with the augment of the levels of supplemented Zn-Met,the extent of decreasing diminished gradually.Effects on reproductive performance: The normal delivery of group B,C and D were 80%、93.33%、93.33%,respectively,were improved by a certain extent comparing with the control group; The mean birth weight of calves were not significantly different between the trial and control groups.But numerical datas shown that supplementing Zn-Met in dietary had the tendency to increase the birth weight of calves; Supplementing Zn-Met in dietary can make dairy cows express empathema earlier,and significantly（P<0.05）.Among the trial groups,the advanced extent of the group C was comparatively large（5.8d）;The oestrous cycles were all in normal range and not significantly different; The levels of serum PRL of group B,C and D were significantly（P<0.05） 1.46 ng/ml、3.08 ng/ml、3.45 ng/ml higher than the group A（control group）. The levels of serum PRL increased with the augment of Zn-Met,but the extent of increasing diminished gradually,as well,the group B was significantly different from group B and D;Comparing with the control group,the trail group had the higher content of E₂ and P₄ both in oestrus and luteal phase. In oestrus,the content of E₂ improved obviously,and in luteal phase, the content of P₄ obviously,but all not significantly different（P>0.05）;Comparing with the control group.the conception rate of the first service increased 6.66、20.00、20.00 percentage points.So,Zn-Met is good at increasing the conception rate of the first service.Results shown that, Supplementing Zn-Met in dietary had some certain promotion on the lactational performance and reproductive performance in dairy cows.Analysis indicated that,the 240mg/kg supplementing amount was the best in the normal dietary（Zn37.15mg/kgDM） and could be used as reference data of the Zn supplementing amount in dietary.更多还原