能量水平、补饲不同碳水化合物类型饲料以及添加过瘤胃氨基酸水平对奶牛热应激的影响

发布时间：2018-12-10 06:17

【摘要】：本研究由两个试验组成,研究了不同能量水平、不同剂量过瘤胃赖氨酸与蛋氨酸组合的添加以及补饲不同碳水化合物类型的饲料对奶牛生理机能、产奶水平、血液生理指标以及对外周血淋巴细胞中热应激相关基因mRNA相对表达量的影响。试验1以日粮中能量水平、补饲饲料的碳水化合物类型和瘤胃保护性氨基酸(RPAA)添加剂量为试验因子,试验采用L9(3~4)正交试验设计。过瘤胃蛋氨酸和赖氨酸的适宜添加量,设RPMet5 gd~(-1)·head~(-1)+RPLys5 gd~(-1)·head~(-1),RPMet10 gd~(-1)·head~(-1)+RPLys30 gd~(-1)·head~(-1),RPMet20 gd~(-1)·head~(-1)+RPLys 60 gd~(-1)·head~(-1) 3个水平;能量水平分别为0.8倍、1倍、1.2倍能量水平。试验结果表明,当日粮能量水平为0.8倍能量需要时,奶牛的产奶量较低,对奶牛热应激产生不利的影响。补饲适量的糖蜜可以缓解奶牛的热应激,但补饲量仍需要研究。当每头牛补饲0.6kg糖蜜时,奶牛干物质采食量没有降低,相应奶牛产奶量有所提高,当糖蜜饲喂量增加时,奶牛干物质采食量出现下降,相应产奶量也开始降低。当过瘤胃蛋氨酸与赖氨酸组合添加量为RPMet20g/d·head+RPLys60 g/d时,奶牛的产奶量、干物质采食量等均较添加另外两个剂量高。在热应激期适量增加奶牛日粮能量水平、补饲一定量的过瘤胃赖氨酸蛋氨酸组合以及补饲适量的糖蜜能够一定程度上缓解奶牛夏季热应激造成的危害。试验2在试验1末期对试验牛群进行尾静脉采血,提取奶牛外周血淋巴细胞,利用荧光定量PCR技术,对奶牛外周血淋巴细胞中HSP70、ATP1A1、GXP3、SOD3基因的相对表达量进行测定,来研究热应激条件下,不同能量水平、不同过瘤胃蛋氨酸、赖氨酸组合添加量以及补饲不同碳水化合物类型的饲料对奶牛热应激相关基因mRNA表达量的影响。试验中日粮能量水平对热应激相关基因表达量影响最大,在1.2倍能量水平下ATP1A1、GXP3的基因表达量显著高于0.8倍能量水平和1倍能量水平组。由于热应激期间,这些基因所调控的酶的活性降低,导致机体代谢出现紊乱。热应激相关基因表达量的增加有助于机体抵抗热应激所产生的危害。根据热应激相关基因的表达量可以推测1.2倍能量水平有利于缓解奶牛热应激。同样补饲压片玉米较补饲糖蜜与补饲麸皮更有利于热应激条件下奶牛的健康,当每头牛每天补饲过瘤胃赖氨酸60g,过瘤胃蛋氨酸20g时效果较好。
[Abstract]:In this study, two experiments were conducted to study the physiological function and milk production level of dairy cattle fed with different dietary carbohydrate types, including different energy levels, different dosages of rumen lysine and methionine, and supplementation of different carbohydrate types of feed. Effects of blood physiological indexes and relative expression of heat stress related gene mRNA in peripheral blood lymphocytes. In experiment 1, the dietary energy level, carbohydrate type and rumen protective amino acid (RPAA) supplementation dose were used as experimental factors. L9 (3N4) orthogonal design was used in the experiment. RPMet5 gd~ (-1) head~ (-1) RPLys5 gd~ (-1) head~ (-1), RPMet10 gd~ (-1) head~ (-1) RPLys30 gd~ (-1) head~ (-1), RPMet20 gd~ (-1) head~ (-1) RPLys 60 gd~ (-1) head~ (-1); The energy levels were 0.8, 1 and 1.2 times, respectively. The results showed that the milk yield of dairy cows was lower when the energy level of daily grain was 0.8 times, which had a negative effect on heat stress of cows. Supplementation of molasses can relieve heat stress in dairy cows, but supplemental feeding still needs to be studied. When each cow was supplemented with 0.6kg molasses, the intake of dry matter did not decrease, and the milk yield of corresponding cows increased. When the amount of molasses increased, the intake of dry matter decreased and the milk yield began to decrease. When rumen methionine / lysine was added to RPMet20g/d head RPLys60 g / d, the milk yield and dry matter intake of dairy cows were higher than those of the other two dosages. During the heat stress period, increasing the dietary energy level, supplementing the rumen lysine methionine combination and the appropriate amount of molasses could alleviate the harm caused by heat stress in summer to some extent. At the end of experiment 1, the blood was collected from the tail vein of the cattle and the peripheral blood lymphocytes were extracted from the cows. The relative expression of HSP70,ATP1A1,GXP3,SOD3 gene in the peripheral blood lymphocytes of the cows was determined by fluorescence quantitative PCR technique. To study the effects of different energy levels, different rumen methionine, lysine combinations and dietary supplementation of different carbohydrate types on the mRNA expression of heat stress related genes in dairy cows under heat stress. Dietary energy level had the greatest effect on the expression of heat stress-related genes, and the gene expression of ATP1A1,GXP3 at 1.2 times energy level was significantly higher than that of 0.8 times energy level and 1 times energy level group. During heat stress, the enzyme activity regulated by these genes decreased, resulting in disorder of metabolism. The increase of heat stress related gene expression can help the body to resist the harm caused by heat stress. Based on the expression of heat stress related genes, 1.2 times energy level can be inferred to alleviate heat stress in dairy cows. The same supplementary feeding of pressed corn was more beneficial to the health of cows under heat stress than that of molasses and bran. The effect was better when each cow was supplemented with 60 g of rumen lysine and 20 g of rumen methionine every day.
【学位授予单位】：河南农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S823.5

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