【作者】 李徐延；

【导师】 张洪友；

【作者基本信息】 黑龙江八一农垦大学 ， 基础兽医学， 2009， 硕士

【摘要】 奶牛泌乳早期能量代谢特点是干物质摄入减少、机体能量需求增加所致的能量负平衡。严重的能量负平衡会造成奶牛酮病、脂肪肝。它们是威胁奶牛泌乳早期代谢健康和泌乳性能的重要的营养代谢病,已被世界奶牛养殖业列为重要的围产期疾病而加以研究和防治。为了有效的缓解奶牛泌乳早期能量负平衡,减少奶牛酮病和脂肪肝的发生,本试验开展了过瘤胃脂肪和过瘤胃葡萄糖对泌乳早期奶牛生产性能和机体能量代谢的影响的研究工作,旨在明确过瘤胃脂肪和过瘤胃葡萄糖预防奶牛泌乳早期能量负平衡的效果,阐明其作用机制,确立其有效的添加剂量,为今后推广应用该制剂提供科学依据。选取产后10~15天,年龄、胎次、产奶量相近,年产奶量大于6吨的荷斯坦奶牛42头,随机分为7组,每组各6头。Ⅰ、Ⅱ、Ⅲ组分别在基础日粮中每头每天添加200g、300g和400g过瘤胃脂肪;Ⅳ、Ⅴ、Ⅵ组分别在基础日粮中每头每天添加200g、300g和400g过瘤胃葡萄糖;Ⅶ组为对照组,饲喂基础日粮。过瘤胃脂肪和过瘤胃葡萄糖分早晚两次混于精料中,任其自由采食,饲喂期20天。通过对试验奶牛在饲喂前、饲喂后10天和20天的干物质摄入量、产奶量、乳汁成分的分析以及血液代谢产物(葡萄糖、β-羟丁酸、游离脂肪酸、尿素氮、总胆固醇和甘油三酯)和激素(胰岛素、瘦素和胰高血糖素)的测定,结果显示:(1)与对照组比较,各试验组干物质摄入量无显著变化(P>0.05);Ⅲ组和Ⅳ组产奶量极显著升高(P<0.01);乳脂肪、乳蛋白、乳糖和乳非脂固形物水平均不显著(P>0.05)。(2)与对照组比较,Ⅲ组血糖浓度显著升高(P<0.05),Ⅴ组血糖浓度极显著升高(P<0.01);Ⅵ组血浆β-羟丁酸浓度显著升高(P<0.05);Ⅴ组血浆胰岛素水平显著升高(P<0.05);Ⅰ组和Ⅳ组血浆胰高血糖素水平显著升高(P<0.05);血浆游离脂肪酸、甘油三酯、总胆固醇、尿素氮和瘦素变化均不显著(P>0.05)。这些结果表明(1)过瘤胃脂肪和过瘤胃葡萄糖能提高奶牛泌乳性能;(2)过瘤胃脂肪能提高血糖水平,从而改善奶牛的能量负平衡;同样地200g和300g过瘤胃葡萄糖能提高血糖水平,改善奶牛的能量负平衡;(3)200g过瘤胃脂肪和200g过瘤胃葡萄糖均能增加经济效益,但200g过瘤胃葡萄糖获得的经济效益最大。更多还原

【Abstract】 Energy metabolism in early lactating cows is characteristic of negative energy balace caused by a decrease of dry matter intake and a increase of body energy demand. The severe negative energy balance can bring about cows’ketosis and fatty liver, which are thought highly of as important metabolic diseases threatening health and milk performance of ealy lactating cows in all dairy cows county. To search for more effctive methods of relieving negative energy balance, decrease incidence of cows’ketosis and fatty liver in early lactation. In the experiment, effects of rument bypass fat and rument glucose on production performance and body energy metabolism were observed to understand its preventive effect on negative energy balance, to clarity its mechanism of action, to establish effectvie additive dosage, and to provide the scientific basis for its application in future.Forty two Holstein cows which have silimar age, parity, and milk yield (more than 6000kg/305d), were randomly divided into seven groups at 10~15 day postpartum, 6 cows in each group. Every day cows in group I, II, and III were fed by a basal diets containing 200g, 300g, and 400g rumen bypass fat respectively. Each cow in groupⅣ,Ⅴ, andⅥwere fed by a basal diets containing 200g, 300g and 400g rumen bypass glucose respectively. GroupⅦis control group fed a basal diet. Rumen bypass fat and rumen bypass glucose are mixed into grain feed in the morning and in the evening, freedom feeding for 20 days. Dry matter intake, milk yield, milk ingredients, blood metabolites (glucose,β-hydroxybutyrate, free fatty acid, urea nitrogen, total cholesterol and triglyceride) and hormone (Insulin, leptin and glucagons ) were measured before feeding and 10 day, 20 day after feeding, results showed that (1) Compared with controls, dry matter intake change nonsignificantly in all treatmemt cows (P > 0.05), and milk yield increased very significantly in group III and IV (P < 0.01), but levels of milk fat, protein, lactose, and solids-not-fat vary nonsignificantly. (2) Compared with controls, concentration of plasma glucose increased markedly in groupⅢ(P < 0.05), and increased very significantly in groupⅤ(P < 0.01). Concentrations of plasmaβ-hydroxybutyric acid increased significantly in groupⅥ(P < 0.05). Level of plasma insulin increased significantly in groupⅤ(P < 0.05). Level of plasma glucagons increased significantly in groupⅠ, andⅣ(P < 0.05). Concentration of plasma free fatty acid, triglyceride, cholesterol, urea nitrogen, and leptin vary non- significantly (P > 0.05).Conclusions obtained that (1) Rumen bypass fat and glucose can improve cows milk performance in early lactation. (2) Rumen bypass fat can raise up plasma glucose level of early lactating cows, thereby improve cows’negative energy balance. As well, plasma glucose level can increase in early lactating cows fed a diet containing 200g and 300g rumen bypass glucose, thereby improve cow negative energy balance. (3) The more economic benefits obtained in early lactating cows fed a diets containing 200g rumen bypass fat or 200g rumen bypass glucose, but the maximum economic benefits obtained in a diet containing 200g rumen bypass glucose.更多还原