Animal Science Department, Agricultural College, Shahrekord University, Shahrekord, Iran
The aim of this study was to compare the effects of using different mixtures of corn silage and absorbents on nutrient digestibility as well as nitrogen and energy status of Iranian fat-tailed native ewes during late pregnancy. Twenty ewes (36±1.5 months of age; 55±6 kg BW) in the late gestation were randomly divided into five equal groups and were fed with corn silage either alone (T1) or mixed with chopped alfalfa (T2), un-chopped alfalfa (T3), chopped wheat straw (T4) and un-chopped wheat straw (T5). All the ewes were fed restricted up to approximately a 33% of their requirements. The results of the study showed that restricted feeding regime caused a negative energy and protein balance in all ewes. Treatment which contained absorbents showed higher DM, OM, and CP intake (P<0.05). However, no significant (P>0.05) effect was revealed among the dietary groups in terms of nutrient digestibility. Nitrogen intake, urinary N, tissue N mobilization, total available N and N deposition in the gravid uterus were affected by the treatments (P<0.05), and treatment contained alfalfa hay as an absorbent showed superiority than other treatments. Pooled data from all ewes showed that fat mobilization have strong negative correlation (P<0.0001) with energy efficiency. It can be concluded that high energy demand during late pregnancy in ewes under a restricted feeding regimen is the main factor of fat mobilization around the tail nuts; and as a result, higher fat mobilization is accompanied with low energy efficiency.
Energy efficiency, Ewes, Fat mobilization, Pregnancy, Corn Silage
