泌乳阶段和处理温度对驴乳中溶菌酶活性的影响

旨在研究驴乳中溶菌酶活性与母驴泌乳阶段和处理温度之间的关系.本研究首先取新鲜牛、羊和驴乳进行乳中溶菌酶活性的比较.为了探究泌乳阶段和泌乳水平对乳中溶菌酶活性的影响,将4～9岁母驴根据日均产奶量水平分为低(400 g以下)、中(400～1 000 g)、高(1 000 g以上)3组,每组随机挑选3头共9头试验动物,连续观...

Effects of Lactation Stages and Heat Treatment Temperature on Lysozyme Activity in Donkey Milk

The study aimed to explore the relationship between lysozyme activity in donkey milk and lactation stages and treatment temperature. The lysozyme activities in fresh milk of cow, sheep and donkey were compared. To investigate the effects of lactation stages and lactation level on lysozyme activity in milk，female donkeys aged 4-9 years were divided into 3 groups according to the average daily milk yield: low (below 400 g), medium (400-1 000 g) and high (above 1 000 g) groups，3 animals in each group, and 9 animals in total were used to observe the lysozyme activity in the milk of female donkeys from the 3rd to 10th lactation month regular continuous sampling every month for 7 days. Finally, mixed donkey milk obtained on 5 sampling days was divided into 6 aliquots, one of which was not treated, and the others were heated at 62 ℃ for 30 min, 72, 77, 82 and 87 ℃ for 15 s, respectively. Lysozyme activity was detected after cooling to study the effect of heat treatment condition on lysozyme activity in milk. The results showed that the lysozyme activity in donkey milk (12 367 U·mL^-1) was significantly higher than that in cow milk (334 U·mL^-1) and sheep milk (233 U·mL^-1) (P<0.05). Lysozyme activity in milk secreted by female donkeys at the 8th lactation month after parturition was the highest (14 383 U·mL^-1) (P<0.05). During the processing of raw milk, sterilization at 62 ℃ for 30 min had no significant effect on lysozyme activity (P>0.05), while sterilization at 72-87 ℃ for 15 s significantly decreased lysozyme activity (P<0.05). Compared with cow and sheep milk, donkey milk has higher lysozyme activity, and long-term sterilization at low temperature does not affect the lysozyme activity.