日粮添加微藻粉对奶牛瘤胃发酵及乳脂脂肪酸组成的影响

Effects of Dietary Supplementation Microalgae Powder on Rumen Fermentation and Milk Fat Fatty Acid Composition of Dairy Cows

为了研究日粮中添加微藻粉对奶牛瘤胃发酵、血浆指标和乳脂脂肪酸组成的影响,选用30头平均体质量(675±21)kg、胎次(3.5±0.2)次、泌乳天数(97±12)d和产奶量(30.0±2.4)kg相近的泌乳奶牛,随机分为对照组(饲喂基础日粮)和试验组(饲喂基础日粮+200 g微藻粉),采用交叉试验设计进行了3期90 d的泌乳试验。结果表明,日粮中添加微藻粉可显著降低瘤胃液中氨态氮浓度,总挥发性脂肪酸的浓度有升高趋势;瘤胃细菌数量不受微藻粉添加的影响,但原虫数量显著下降,瘤胃厌氧真菌也有降低的趋势;血糖、总蛋白、尿素氮、甘油三酯、谷草转氨酶和谷丙转氨酶等血浆生化指标组间无显著变化,但微藻粉组的超氧化物歧化酶活性、硫代巴比妥酸反应物与丙二醛较对照组有升高趋势。与对照组相比,干物质采食量和标准乳量无显著变化,产奶量显著提高,乳成分中乳蛋白率、乳糖率和乳固形物率无明显变化,但乳脂率显著降低。微藻粉的添加显著改变了乳脂脂肪酸组成,不饱和脂肪酸比例增加而饱和脂肪酸降低,尤其是显著提高了乳脂中n-3多不饱和脂肪酸中的DHA含量(0.59%)。奶牛日粮中添加200 g/d微藻粉对奶牛瘤胃发酵及机体健康状况无负面影响,并能提高乳脂脂肪酸中DHA含量。

To study the effects of dietary adding microalgae powder on rumen fermentation,plasma parameters and fatty acid composition of milk fat in dairy cows,30 heads with average body quality(675±21)kg,fetus 3.5±0.2,lactation days(97±12)d and milk yield(30.0±2.4)kg were randomly divided into control group(fed with basic diet)and experimental group(fed with basic diet+200 g microalgae powder)with a crossover arrangement.The result showed that dietary adding microalgae powder significantly decreased the concentration of ammonia nitrogen in rumen fluid,the concentration of total volatile fatty acids tended to increase,and the pH value of rumen fluid did not change significantly.The number of bacteria in rumen was not affected by the addition of microalgae powder,but the number of protozoa decreased significantly,and the number of anaerobic fungi also decreased.There were no significant changes in blood glucose,total protein,urea nitrogen,triglyceride,aspartate aminotransferase and alanine aminotransferase,but the superoxide dismutase activity,thiobarbituric acid reactant and malondialdehyde in microalgae powder group were higher than those in control group.Compared with the control group,the dry matter intake and standard milk volume had no significant change,the milk yield increased significantly.The milk protein rate,lactose rate and solids rate had no significant change,but the milk fat rate decreased significantly.The diet supplemented with microalgae powder significantly changed the fatty acid composition of milk fat,decreased the proportion of saturated fatty acids and increased unsaturated fatty acids,especially significantly increased the DHA content of n-3 polyunsaturated fatty acids in milk fatty,up to 0.59%milk fat.Adding 200 g/d microalgae powder to dairy diet had no negative effect on rumen fermentation and body function,and could increase DHA content in milk fatty acids.