Abstract
The objectives of this study were to evaluate the effects of feeding undegradable intake protein (VIP) on body weight changes and the return to estrus of Awassi ewes during the early postpartum period. Twenty multiparous Awassi ewes $(BW=57.4{\pm}3.0kg)$ were randomly assigned to two dietary treatment (10 ewes per treatment) for 4 weeks in a completely randomized design. Experimental diets were isonitrogenous, isocaloric, and were formulated to contain either 20% (CON) or 35% (SBM) of the dietary CP as UIP. On day $9{\pm}3$ postpartum (day 0=parturition) ewes were housed in individual pens. Feed intake was recorded daily. Dry matter intake (DMI), organic matter intake (OMI), crude protein intake (CPI), undegradable protein intake (UPI) and metabolizable energy intake (MEI) were higher (p<0.05) for ewes on SBM diets compared with ewes on CON diet. Ewes receiving SBM diet gained more (p<0.05) weight than the controls (5.3 vs 0.5 kg). There was a tendency (p>0.10) for SBM ewes to have more luteal activity than the controls. Ewes in the SBM group came into estrus 4 days earlier than CON ewes (p<0.10). These results indicate that Awassi ewes receiving adequate nutrition are capable of returning to estrus one month postpartum thus posing the possibility of being able to lamb every 6 months.