Journal of Animal Science, Vol 78, Issue 9 2275-2281, Copyright © 2000 by American Society of Animal Science

JOURNAL ARTICLE

Effects of dietary protein concentration on postweaning growth of Boer crossbred and Spanish goat wethers

I. Prieto, A. L. Goetsch, V. Banskalieva, M. Cameron, R. Puchala, T. Sahlu, L. J. Dawson and S. W. Coleman
E (Kika) de la Garza Institute for Goat Research, Langston University, OK 73050, USA.

Boer (3/4) x Spanish (1/4) (BC; n = 23) and Spanish (SP; n = 22) goat wethers, 4 to 4.5 mo of age and 17.6 and 19.4 kg initial BW, respectively (SE = 0.57), were used to determine effects on growth of protein concentration in 70% concentrate diets provided for ad libitum intake for 30 wk in confinement. Offered diets contained 10.2, 14.2, 18.3, and 23.6% CP (DM basis), and CP concentration in consumed DM was 9.3, 13.8, 17.1, and 22.1% (P1, P2, P3, and P4, respectively); supplemental protein was from soybean meal for P1 and P2 and from soybean meal plus a blend of blood, fish, and feather meals for P3 and P4. Dry matter intake was similar between breeds and among diets (732, 712, 698, and 740 g/d for P1, P2, P3, and P4, respectively; SE = 27.0). Average daily gain was greater for P2 (P = 0.07) and P4 (P < 0.05) than for P1 (76, 90, 85, and 100 g/d for P1, P2, P3, and P4, respectively; SE = 5.3) and for BC than for SP (97 vs 78 g/d, SE = 3.7; P = 0.05). Similarly, ADG:DMI was lowest (P < 0.05) among diets for P1 (0.106, 0.126, 0.121, and 0.132 for P1, P2, P3, and P4, respectively; SE = 0.0053) and greater (P < 0.05) for BC than for SP (0.135 vs 0.108; SE = 0.0037). In conclusion, with 70% concentrate diets, the protein requirement for both BC and SP seemed to have been met by consumption of diets with at least 14% CP, with no apparent benefit from addition of ruminally undegraded protein.