Acta Veterinaria et Zootechnica Sinica ›› 2022, Vol. 53 ›› Issue (4): 1089-1095.doi: 10.11843/j.issn.0366-6964.2022.04.009

• ANIMAL GENETICS AND BREEDING • Previous Articles     Next Articles

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

WANG Han1, HU Yuling1, ZHAO Chenkun2, YANG Zhipeng2, ZENG Shenming1*   

  1. 1. College of Animal Science and Technology, China Agricultural University, Beijing 100193, China;
    2. Zhangjiakou Sangyang Animal Husbandry Co. LTD., Zhangjiakou 075831, China
  • Received:2021-09-02 Online:2022-04-23 Published:2022-04-25

Abstract: 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.

Key words: donkey milk, lysozyme, antibacterial activity, pasteurization

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