Efficiency of utilization of dietary energy for milk production in lactating crossbred cattle (Bos Indicus)

The present study was conducted on efficiency of utilization of dietary energy for milk production in lactating crossbred cattle. ۱۸ lactating crossbred cattle of early to mid-lactation, approximate body weight (۳۷۵.۳۹±۲۳.۴۳ kg), milk yield, parity and stage of lactation were divided into three groups of six animals each and were fed ۰, ۵۰ and ۱۰۰% diammonium phosphate (DAP) in the mineral mixture of concentrates for ۱۲۰ days. The chaffed mixed roughage (berseem + wheat straw) and concentrate mixture was fed to supply about nearly ۱۸:۸۲ concentrate to roughage ratio on dry matter basis. Tap water was available to the animals twice daily. A metabolism trial of seven days was conducted at the end of experiment to study digestibility of organic nutrients and balances of energy. DAP did not affect the nutrient intake, body weight changes, digestibility of Dry matter (DM), Crude protein (CP), Ether extract (EE), Crude fiber (CF), Nitrogen free extract (NFE) and daily milk yield. It was concluded that the at ۴۶.۰۷ Mcal Gross energy intake level the losses in feces, urine, methane and heat production was ۴۵.۸۲%, ۵.۴۰%, ۴.۳۱% and ۳۳.۰۱%, respectively, and net energy retention for milk production was ۱۱.۴۳%. The gross efficiency of conversion of metabolic energy ME for milk production was ۳۵.۶۹% and the net efficiency of conversion of ME for milk production was ۳۹.۵۶%.

کلیدواژه ها:

Diammonium phosphate ، Dietary energy ، Cattle ، Milk yield ، Gross energy