Protein levels for Chios lambs given high concentrate diets

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Abstract
The effects of 3 dietary crude protein (CP) levels (178, 158 and 137 g/kg dry matter) on growth characteristics of Chios lambs and the digestibility of the diets were studied. Male lambs grew faster, consumed more feed and utilized feed more efficiently than female lambs. The final weight and weight gain of male lambs on the high CP diet were higher than those on the low CP diet. Serum urea N was correlated (r = 0.55) with dietary protein level in the males, but not in the females. Neither diet nor sex had a significant effect on rumen NH3-N concentration or pH. Rumen microbial protein was highest (P < 0.01) on the high CP diet. CP level had no effect on any of the carcass measurements. There were no significant differences among diets in the apparent digestibility of dry matter, organic matter or CP. Urinary N output increased in response to increments of dietary CP concentration. The CP requirements of female Chios lambs are considerably lower than those of males. Maximum growth of male Chios lambs during this stage of fattening can be obtained with 16% (dry matter) dietary CP concentration.