Effects of milk production and milk quality on calf growth and health indexes of high-generation heifers
The purpose of this experiment was to study the effects of nursing male calves on calf growth and development,serum indexes,and first estrus and breeding of cows after farrowing.15 high-generation heifers[weighing(510±4.92)kg]and 15 calves born with similar calving time and parity(3 births)were selected,and 10 milk calves[(40.49±2.54)kg]with similar birth date and weight were selected for breastfeeding,and were randomly divided into 4 groups,the control group was cows without calves,and the cows in 1 group were breastfed until 4 months after giving birth,the milk calves were weaned for 30 days.The cows in the test group 2 were weaned for 5 months postpartum,the milk calves were weaned at 60 days,and the cows in the test group 3 were weaned for 6 months after delivery,the milk calves were weaned at 90 days.The test period was from May 10 to November 15,2022,with a test period of 180 days,to measure the milking amount,detect the content of nutrients in normal milk,and detect the growth and development and blood biochemical indicators of milk calves.The results showed that:(1)The average daily lactation volume of 120,150 days and 180 days after delivery increased by 15.27％,34.34％and 25.08％,and the monthly milk production increased by 16.25％,37.42％and 35.66％(P＜0.01)respectively compared with 90 days,and the peak period of lactation began to be at 150 days.Milk fat was significantly higher than the average milk fat rate of 25.00％(P＜0.05)at 90 days after delivery,milk protein was significantly higher than average milk protein by 10.14％at 120 days postpartum,and lactose was significantly higher than average lactose by 6.38％(P＜0.05).(2)The body weight of the 120 d calves in the groups 2 and 3 increased by 3.97％and 8.06％(P＜0.05)compared with the experimental group 1,and the weight of the milk calves in the 180 d of the experimental groups 2 and 3 increased by 3.36％and 7.06％(P＜0.05)respectively compared with the experimental group 1.Compared with group 1,the aspartate aminotransferase(AST)of calves in groups 2 and 3 decreased by 14.95％and 11.32％(P＜0.05),the immunoglobulin E(IgE)of group 2 increased by 4.31％and 5.05％(P＜0.05)compared with groups 1 and 3,and interleukin-2(IL-2)decreased by 3.17％and 3.68％(P＜0.05)compared with group 1,respectively.(3)The first postpartum estrus time of cows in the control group and trial group 1 decreased by 28.09％and 20.75％compared with the test group 2,and decreased by 32.87％and 25.90％(P＜0.05)compared with the test group 3,and the postpartum breeding time of the cows in the control group and test group 1 was shortened by 25.80％and 18.93％compared with the test group 2,and 29.50％and 24.00％shorter than that in the test group 3(P＜0.05),serum estradiol(E2)levels in the control group on the 10th day of estrus increased by 30.80％,41.00％and 45.00％compared with the experimental group,and follicle stimulating hormone(FSH)increased by 41.84％,52.75％and 61.63％compared with the experimental group(P＜0.05).Considering the lactation and reproductive performance of high-generation heifers,it was recommended that the calves should be gradually weaned for 90 days,and the cows could continue to breastfeed the milk calves and the milk calves could be weaned for 90 days,so as to make full use of the high lactation performance of the cows.
high-generation sub-miscellaneousmilk productionmilk qualitymilk calvesgrowth and development
万方数据
维普
