The Effects Of Different Energy Intake On The Performance And Blood Indexes Of Dairy Cows

In this research, through animal trial and analysis on blood related indexes, the effects of different energy intake on the dry material intake (DMI) of cows after delivery and the relationships between them were investigated, the neuroendocrine regulation mechanisms on the reduce of dry matter intake and fat mobilization of peripartum dairy cows were explored. And this research provided experimental and theoretic basis for rectifying and alleviating negative energy balance, preventing and curing energy metabolism diseases of peripartum dairy cows.Thirty Chinese Hostein cows, with milk yield exceeding 5000Kg, were randomly allocated into three groups, three groups were respectively fed with standard diet (energy meets the Chinese feeding standing of dairy cow), experiment I diet (energy concentration is 20% higher than that of standard diet) and experiment II diet (energy concentration is 20% lower than that of standard diet) for 28d before delivery. After delivery, all the cows were offered standard diet for 56d. During the experiment, the blood was sampled termly, and the DMI, blood indexes such as glucose, triglyceride, low density lipoprotein (LDL), ketone body, NEFA and the levels of some hormones related with energy metabolism such as leptin, NPY, Ins GH live weight were detected, at the same time, the performances of dairy cows were measured. The results showed that different energy intake during antepartum affected the DMI and the milk yield of peripartum cows significantly. The lower energy intake of antepartal dairy cows significantly increased the DMI, the milk yield, the concentrations of leptin and NPY in blood of postpartum dairy cows. The cows intaking lower energy restore their appetite more quickly, their DMI increased more quickly, reached the peak in a shorter time and kept a longer period. Therefore, lower energy intake increased the DMI of cows after delivey, alleviated the effects of negative energy balance and improved the conditions of cows. The higher energy intake of cows before delivery decreased the concentrations of leptin and NPY in blood, the cows restore their appetites more slowly, the DMI increased more slowly, required a longer time to reach the peak. Therefore, higher energy intake was adverse to the DMI increase of postpartum cows, and higher energy intake strengthened the effects of negative energy balance and aggravated the body conditions of cows. Compared with control, the DMI and milk yields of cows intaking lower energy respectively increased by 3%-7% and 4%-8% after delivery. The DMI and milk yields of the cows intaking higher energy respectively decreased by 12%-17% and 10%-18%. In addition, lower energy intake increased the blood glucose concentration and decreased the concentrations of TG, ketone body, NEFA and Ins in blood of cows after delivery. It could be found that the extent of negative energy balance in antepartal cows intaking higher energy was more serious than that in antepartal cows intaking lower energy after delivery, the same situation happened to the fat mobilization, the higher energy intake tended to promote the occurrences of energy metabolism diseases such as ketone body and fat liver.On the whole, it could be concluded that energy intake of peripartum dairy cows significantly affected the DMI of cows after delivery. Higher energy intake decreased the DMI of cows, aggravated the extent of negative energy balance, was likely to promote the occurrences of energy metabolism diseases such as ketone body and fat liver after delivery. The DMI reduction of antepartal cows intaking higher energy after delivery was likely to be related with the reduction of the synthesis and release of the NPY.