关键词: 犊牛, 能量, 代谢, 利用率, 消化模式

Abstract: The objective of the experiment was to study the transition of digestible model, energy conversion rate and the characteristics of energy metabolism of the calves. Three 2-day-old Holstein male calves were selected to carry out digestion-metabolism experiment. The results showed that the digestibility of the diet energy declined gradually with the month, the average was 73.73%, the metabolic rate of digestible energy stabilized during the first 3 months and then decreased from 3rd to 5th month, finally returned to normal, the average was 84.68%, the metabolic rate of gross energy declined gradually during the first 5 months and then returned, the average was 62.68%, the ratio of urinary energy to digestible energy was 11.44%,the ratio of methane energy to digestible energy increased during the first 4 months and then decreased during the last 2 months, the average was 3.65%, the ratio of heat production to digestible energy showed a trend of increased firstly and then decreased, the average was 43.86%, the ratio of retention energy to digestible energy was 41.01%. The average heat production was 395.71 kJ/kg W^0.75, the net energy for gain was 10.97 MJ/kg. The results indicate that the fasting heat production of calves was more than that of mature cows, while the net energy for gain was less than that of mature cows.

Key words: calves, energy, metabolism, availability, digestible model