日粮中添加不同脂肪源对奶牛瘤胃液挥发性脂肪酸及乳脂中共轭亚油酸比例的影响

以3头装有永久性瘤胃瘘管的经产荷斯坦奶牛为试验动物,采用3×3拉丁方设计,研究在日粮中添加不同油料籽实(即葵花籽、亚麻籽、菜籽)的外源脂肪,对奶牛瘤胃液中乙酸、丙酸、丁酸含量变化的影响,以及对乳脂中共轭亚油酸(CLA)、多不饱和脂肪酸(PUFA)的比例以及血浆中长链脂肪酸比例变化的影响。3种日粮的粗脂肪含量基本相同。结果表明:日粮中添加3种不同油料籽实,对奶牛瘤胃液中乙酸、丙酸、丁酸含量及乙/丙比影响差异不显著(P>0.05);对乳脂中的共轭亚油酸(CLA)比例及其他多不饱和脂肪酸(PUFA)比例的影响差异显著(P<0.05)。葵花籽作为外源脂肪显著提高乳脂中CLA的比例;3组间的血浆中C14:0、C16:0、C18:0的比例差异不显著(P>0.05),菜籽组C18:1的比例显著高于亚麻籽组和葵花籽组(P<0.05),而后2组则差异不显著(P>0.05),亚麻籽组和葵花籽组t-C18:1、C18:2的比例与菜籽组的差异达到显著水平(P<0.05),而亚麻籽组和葵花籽组则差异不显著(P>0.05)。

Eeffects of Different Dietary Fat Source on Ruminal VFA and Milk CLA of Lactating Cows

Three parous Chinese Holstein lactating cows with permanent cannulas on rumen were used as experimental animals.A 3×3 Latin square design was used to study the effects of different kinds of oil seeds(sunflower seed,flaxseed and rapeseed,with the nearly same fat content in the diets) as extraneous fat on the changes of ruminal acetate,propionate and butyrate concentrations of lactating cows.In addition,the aim was to study the effect of different kinds of oil seeds on the proportions of milk CLA and other PUFAs,and the proportional changes of long chain fatty acids in plasma.The results showed that no significant differences were found in the ruminal concentrations of acetate,propionate and butyrate,and the ratio of acetate to propionate(P > 0.05),when adding 3 kinds of oil seeds in the diets.However,the effects on the proportions of milk CLA and other PUFAs were significantly different among 3 diets(P < 0.05).The sunflower seed Group apparently improved the proportion of milk CLA(P < 0.05),while that proportion of C14:0,C16:0 and C18:0 in plasma were insignificant among 3 diets(P > 0.05).In addition,the C18:1 proportion in the Rapeseed Group was significantly higher than that in the flaxseed group and sunflower seed group(P < 0.05),while no apparent differences were found between the latter two groups(P > 0.05).No significant differences were found in the plasma indices among three diets(P > 0.05).The proportions of t-C18:1 and C18:2 in the rapeseed group were significantly different from that in the flaxseed group and sunflower seed group(P < 0.05),while no apparent differences were found between the latter two groups(P > 0.05).