Authors : Mehmet Ali Bal and Hale Yarar
Abstract: Two levels of dietary CP on growth performance, feed efficiency and blood parameters of Holstein heifers and steers were examined. Experimental diets consisted of 12 and 16% CP along with 2.5 Mcal kg 1 of ME (DM basis). Ratios of CP: ME were 49 and 64 g/Mcal for 12 and 16% CP containing diets, respectively. Eight animals were assigned to each experimental diet in a 2X2 factorial arrangement of completely randomized design for 8 wk period. Diets containing 48% corn silage and 52% concentrate (DM basis) were fed twice daily in a total mixed ration. Intake of DM was higher for 12% CP (11.0 kg d 1) compared to 16% CP containing diet (7.7 kg d 1) across the groups. There was a higher BW gain for steers (1.27 kg d 1) compared to heifers (0.99 kg d 1) but no significant dietary CP level difference was observed for BW. Feed efficiency was higher for 16% CP (0.17) compared to 12% CP containing diet (0.11). There was no significant difference detected for serum urea N (8.6 mg dL 1) and creatinine (1.1 mg dL 1) concentrations between treatment groups. Data indicates that heifers during the growth period responded to 12% dietary CP better than 16% CP based on higher BW gain (1.16 kg d 1) and lower serum urea N concentration (8.3 mg dL 1). In steers, no difference in BW gain but higher feed efficiency (0.17 vs. 0.11) made 16% CP containing diet more preferable than 12% CP during the growth period.
Mehmet Ali Bal and Hale Yarar , 2006. Effects of Dietary Crude Protein Level on Growth Performance and Blood Parameters of Holstein Heifers and Steers Fed Ad Libitum. Journal of Animal and Veterinary Advances, 5: 215-219.