The effect of feeding agricultural by-products on performance of lactating Awassi ewes

The objective of this study was to evaluate the effect of feeding agricultural by-products on the performance of lactating Awassi ewes. Forty ewes weighing 63.1 +/- 2.78 kg (mean +/- SEM) and 4 +/- 1 years old were assigned at random to four isonitrogenous diets viz. (1) conventional (CON), (2) olive cake (OC), (3) tomato pomace (TP) and (4) citrus pulp (CIP). By-products were included in the diets at the rate of 20% of the dry matter (DM). Animals were individually housed, fed ad libitum and performance was recorded over a 7-week period. At the end of the performance trial, 6 ewes/treatment were randomly selected to perform a digestibility study. The digestibilities of the attributes of the diets were all lower (not significant) for CIP than the other three diets which had similar values. This difference was most notable for NDF where the value was 46% for CIP and ranged from 58 to 61% for the other diets (P < 0.44). Daily DM and OM intakes tended to be greater (P < 0.10) in the OC than in the TP group, while the difference in NDF and ADF intake was significant (P < 0.01) among all treatments (mostly in favor of the OC treatment). Daily intake of DM, OM and CP were lower for CIP than for CON but the differences were not significant; however, animals on the CIP diet had significantly (P < 0.05) lower intakes of NDF (0.56 vs. 0.67 kg/d) and ADF (0.35 vs. 0.39 kg/d) than those fed CON. There were no significant differences among treatments with respect to initial body weight (BW), final BW, BW change, milk production or milk composition except for milk fat content which tended to be greater for CON (7.42%) than for the other three treatments (range 6.21-6.95%; P < 0.08). The difference for milk fat content between CON and the CIP diet (6.21%) was significant (P < 0.05). The current results indicate that agricultural by-products (olive cake, tomato pomace or citrus pulp) can be included at a level of 20% of the DM content of conventional diets of lactating Awassi ewes without any detrimental effects on animal performance. (C) 2013 Elsevier B.V. All rights reserved.