【作者】 张克春；

【导师】 王小龙；

【作者基本信息】 南京农业大学 ， 兽医， 2006， 博士

【摘要】 奶牛在产后的代谢改变主要表现为能量负平衡(negative energy balalice，NEB)。NEB不但引起奶牛产奶量下降，而且造成奶牛繁殖性能降低、使用年限缩短，并对营养代谢性疾病和感染性疾病发病率易感。脂肪是一种理想的供能物质，国外大量研究证实奶牛日粮中补充脂肪可改善奶牛泌乳期的能量负平衡，但在我国尚处于起步阶段。本文主要研究了瘤胃保护性脂肪对高产奶牛生产性能和血液生化指标的影响，为生产上推广应用瘤胃保护性脂肪提供科学根据。研究1上海地区某奶牛群场乳奶牛疾病流行趋势的调查对2000～2004年上海地区某奶牛场泌乳奶牛产奶量、繁殖性能和感染性疾病进行了调查。结果表明，成乳牛产奶量逐年上升，至2003年平均单产已达到8000kg。临床乳房炎发病率在2000～2003年间无显著差异(P＞0.05)，临床乳房炎发病率2004年比2000年时增加了0.9％(P＜0.05)。隐性乳房炎发病率呈逐年升高趋势，2004年比2000年的隐性乳房炎发病率提高了14.8％(P＜0.05)。各年间子宫内膜炎和胎衣不下发生率无明显的变化规律。相关性分析显示，年平均情期受胎率和年平均繁殖率下降呈下降趋势，与产奶量呈显著负相关(P＜0.05)。结果表明，产奶量上升所致能量负平衡加剧与高产奶牛繁殖性能下降有密切联系。研究2瘤胃稳定性脂肪对产后奶牛奶产量、体况和牛奶成份的影响选择经产、胎次相同和产奶量相近的荷斯坦奶牛40头，采用配对分组设机分为对照组和试验组，每组20头。对照组全程饲喂基础日粮，试验组饲喂基础日粮+400g瘤胃稳定性脂肪。结果：瘤胃稳定性脂肪酸对奶牛采食量无显著影响(P＞0.05)；试验组牛产奶量显著升高(P＜0.05)，乳脂率呈上升趋势(P＞0.05)，但乳蛋白率未见显著变化(P＞0.05)；产后90天的体况评分(Body Condition Scoring，BCS)值两组问有显著变化；牛奶体细胞(somatic cell counts，SCC)呈下降趋势(P＞0.05)。上述结果表明，补充瘤胃稳定性脂肪可提高奶牛泌如乳性能。研究3瘤胃稳定性脂肪对产后奶牛临床血液学的影响选择经产、胎次相同和产奶量相近的荷斯坦奶牛40头，采用配对分组设机分为对照组和试验组，每组20头。对照组全程饲喂基础日粮，试验组饲喂基础日粮+400g瘤胃稳定性脂肪。试验结果表明，添加瘤胃稳定性脂肪提高了围产期饲料能量密度，奶牛产后的奶产量显著提高，但对红细胞数和PVC、MCV、MCH、MCHC和淋巴细胞数均无明显影响；试验组奶牛外周血白细胞总数轻度上升(P＞0.05)。上述结果表明，补充瘤胃稳定性脂肪对于改善机体免疫机可能有一定的作用。研究4瘤胃稳定性脂肪对产后奶牛血液生化指标的影响选择经产、胎次相同和产奶量相近的荷斯坦奶牛40头，采用配对分组设机分为对照组和试验组，每组20头。对照组全程饲喂基础日粮，试验组饲喂基础日粮+400g瘤胃稳定性脂肪。分别于产后0、15、30、45、60、75和90d经尾静脉采血，检测血浆总蛋白、白蛋白、球蛋白、葡萄糖、尿素氮和非酯化脂肪酸(nonesterified fatty acids，NEFA)浓度。结果：瘤胃稳定性脂肪对血浆总蛋白、白蛋白、球蛋白、葡萄糖、尿素氮、血清钙、甘油三酯和胆固醇无显著影响，但引起NEFA浓度在产后30d内显著升高(P＜0.05)。上述结果表明：在奶牛产后日粮中添加400g瘤胃稳定性脂肪对血液蛋白质、葡萄糖代谢无显著影响，但可在短期内促进体内脂肪代谢。研究5瘤胃稳定性脂肪对奶牛群体生产和繁殖性能的影响选择年龄、胎次、泌乳日龄和上胎305天产奶量相近的679头奶牛，随机分为2组。其中对照组380头，试验组379头。从产后第8d起在试验组奶牛日粮中逐渐添加瘤胃稳定性脂肪百事美T-300(BERGAFAT T-300)，到第14d每头每天喂100g，以后每6d递增喂100g，产后26d添加量达到400g，直到产后100d。从产后101d开始，按照每6d递减100g的方式，在产后119 d停止添加。结果表明，试验组奶牛奶产量、乳脂率、体况评分(BCS)较对照组升高，产犊间隔较对照组缩短，全年情期受胎率和年繁殖率以及初产牛和经产牛中产后80天发情牛的比例显著高于对照组，胎衣不下的比例和产后45天内子宫炎发病率较对照组明显降低。上述结果表明，补充瘤胃稳定性脂肪可提高奶牛生产和繁殖性能。上述结果提示：1．产奶量上升所致能量负平衡加剧与高产奶牛繁殖性能下降和感染性疾病发病率升高有密切联系。2．在产后奶牛日粮中补充瘤胃稳定性脂肪对红细胞状态、血浆蛋白、葡萄糖和血钙等生化指标无显著影响，但可显著提高产奶量作用，升高乳脂率、降低牛奶SCC。3．添加瘤胃稳定性脂肪也可显著提高产后奶牛繁殖性能，具有推广应用的价值。更多还原

【Abstract】 Metabolic changes in post-parturient dairy cows are typically characterized by negative energy balance (NEB),which results in not only reduced milk yield,but also reduced reproductivity,shortened service period and,increased susceptibility to metabolic disorders and infectious disease.Supplemental fat,an energy substance, has been demonstrated to prevent negative energy balance in lactating dairy cow in many researches oversea.However,up to date,there are limited reports focused on this event in China. Accordingly,the present study was conducted to examine the effect of supplemental rumen-protected fat on production and plasma metabolite in dairy cow with high milk yield after calving, so as to provide a basis for generalization of this kind of products.Study 1 Prevalence trend of diseases in lactating cows in a dairy herd located in Shanghai areaThe present survey was focused on the milk yield, reproductivity, and incidence of infectious diseases in lactating dairy cow from 2000 to 2004.It was found that the milk yield was increased and peaked at 8000kg in 2003. With the increasing of milk yield, the incidence of the mastitis and endometritis don’t tend to increase correlatively, and the conception rate of oestrus and reproduction rate were interrelated to reduce.It was demonstrated that the decreased reproductivity is associated with intense negative energy balance resulting from increased milk yield in high yield cows. Study 2 Effect of rumen-undegraded fat on milk yield,body condition scoring and milk composition in post-parturient dairy cowsForty multiparous Holstein dairy cows with similar parity and milk yielding of the last year were allocated equally into a control and an experimental group according to matched-pair grouping design.Beginning at the day of parturition until 90 days after parturition,cows in the experimental group were fed basic diet supplemented with 400 g rumen-undegraded fat. It was found that rumen-undegraded fat did not alter dry matter intake (DIM) (P>0.05).However,it increased milk yielding (P<0.05).Milk fat percentage tended to be increased by supplemental fat,although the differences between the two groups were not pronounced (P>0.05).There were no differences in milk protein percentage between the two groups (P>0.05).However,it tended to reduce somatic cell counts (SCC) in milk ( P>0.05).Body Condition Scoring (BCS) in two groups’ showed significantly change.It was concluded that supplemental fat increased milk performance.Study 3 Effect of rumen-undegraded fat on clinical hematology in post.parturient dairy cowsForty multiparous Holstein dairy cows with similar parity and milk yielding of the last year were allocated equally into a control and an experimental group according to matched-pair grouping design. Beginning at the day of parturition until 90 days after parturition,cows in the experimental group were fed basic diet supplemented with 400 g rumen-undegraded fat.It was found that rumen-undegraded fat did not significantly alter RBC,PCV and MCV,MCH,MCHC (P>0.05).Supplemental fat had minor effect on the total number of peripheral leukocytes and the number of lymphocyte (P>0.05).It was concluded that supplemental fat improved immune function to a certain extent.Study 4 Effect of rumen-undegraded fat on plasma metabolites in post-parturient dairy cowsForty Holstein dairy cows were allocated equally into a control and an experimental group according to matched-pair grouping design. Beginning at the day of parturition until 90 days after parturition,cows in the experimental group were fed basic diet supplemented with 400 g rumen-undegraded fat.Blood samples were collected from vena caudalis for detection of plasma total protein,albumin,globin,glucose,urea nitrogen and nonesterified fatty acids (NEFA) on days 0,15,30,45,60,75 and 90 after parturition,respectively.It was found that rumen-undegraded fat did not alter the concentration of plasma total protein,albumin,globin or glucose.They were no significantly difference in serum calcium,tfiglycefide,cholesterol concentration in different groups.However,supplemental fat significantly increased plasma NEFA concentration during the first 30 days after parturition.In conclusion,supplemental fat enhanced lipolysis in a short term;however,it had no adverse effect on plasma protein and glucose metabolite.Study 5 The effect of rumen-undegraded fat on productivity and reproductivity in a dairy herdCows with similar years of age, parities,onset of lactating and previous 305-day milk yield were divided into a control group (308 cows) and a treated group (379 cows) at random. Starting at days 8 after parturition, supplemental rumen-undegraded fat was increasingly added to the basal diets of the treated group until every cow received 100 g on days 14 after parturition.Thereafter, 100 g rumen-undegraded fat was increased by degrees at an interval of 6 days until 400 g were added on day 26 after parturition,and then remained constant until days 100 after parturition.Beginning at days 101 after parturition, rumen-undegraded fat was decreased progressively at a rate of 100 g every 6 days until supplementation of fat was canceled on days 119 after parturition. It was found that supplemental rumen-undegraded fat increased the milk yield, milk fat percentage and body condition score (BCS).Cows in rumen passed fat-treated group had shortened interval of calving, increased concept rate of oestrus, breeding coefficient per year and percentage of oestrus both in primiparous and multimiparous cows within 80 days after calving.Incidences of placenta retention and metritis were deceased by supplemental rumen-undegraded fat.It was demonstrated that rumen-undegraded fat improved both the productivity and reproductivity in dairy cows.It demonstrated that:1.The increased incidence of infectious diseases and decreased reproductivity is associated with intense negative energy balance resulting from increased milk yield in high yield cows2.Supplementation of rumen-undegraded fat to the diet of postpartum cows had no effects on blood cell status, plasma protein,glucose and calcium.However,it significantly increased milk yield, and tended to elevate milk fat percentage and to reduce SCC in milk.3.Supplemental rumen-undegraded fat was also shown to improve reproductivity inpostpartum cows in a dairy herd.Based on those findings,it is suggested that rumen-undegraded fat can be generalized for practice.更多还原