Abstract
A field experiment was conducted to investigate the lambing rate, lamb growth and survivability of newborn lambs of pregnant Najdi ewes fed two different total mixed rations (TMR) with different levels of energy and protein viz. higher protein than recommended by National Research Council (1985; TMR1), and higher energy than National Research Council (1985; TMR2) compared with the traditional feeding system of barley and alfalfa hay; Control). A total of 96 Najdi ewes, about nine months old, were divided randomly into three dietary treatments two months before parturition (Late gestation). Lambing percentage, lamb birth weight, lamb weaning weight and mortality rate were recorded. Blood samples were collected regularly during the different stages and analyzed for different important nutritional metabolites. In addition, colostrum, at parturition, and milk samples on day 30, 60 and 90 postpartum were collected for nutrient contents. The results showed an improvement in lambing rate of ewes in T1 and T2 (81 and 80%, respectively) compared to the control (78.8%). Moreover, ewes in T2 showed higher lambs survival rate and average daily gain up to 90 days. There was no significant effect (P>0.05) of treatments on the colostrum composition but milk composition altered by the time interval. Blood metabolites did not vary among the groups, however, urea concentration was significantly (P<0.05) in the T1 and T2 groups. In conclusion, feeding Najdi ewes a diet containing higher energy and protein than recommended by National Research Council (1985), in comparison with the traditional feeding system, improved the lambing rate and growth of the newborns.