Metabolizable energy intake and changes in body weight and body condition of pelibuey ewes fed three levels of roughage diets under tropical conditions

the aim of the study was to evaluate the effect of metabolizable energy intake (mei) on changes in body weight (bw) and body condition score (bcs) of non pregnant, non lactating pelibuey ewes. the experiment had two phases: first, 24 three-yr-old ewes were kept in pens (six ewes per pen) and fed for 60 days to homogenize bw and bcs. thereafter ewes with bw 37.2 ± 4.1 kg, bcs of 2.5±0.12 (mean±sd), were randomly divided in groups of six animals, and one group was slaughtered for baseline measurements; the remaining groups were assigned to a completely randomized experimental design and individually penned in metabolic crates, and fed at low (l), medium (m) and high (h) mei for 65 days. feeding was based on taiwan grass (pennisetum purpureum) given at a rate of 44 g dm/kgbw0.75/day, and a supplement (140 g cp/kgdm and 11.5 mj me/kgdm) given at 0, 16 and 32 g dm/kgbw0.75/day for l, m and h respectively. after 65 days, daily bw changes were: -107, -21 and 30 g/day for l, m and h respectively. changes in bcs were: -0.8, 0.0 and 0.5 points for l, m and h respectively. mei was different (po.05) among l, m and h, but m and h levels did not differ (p>0.05), mei were 0.247, 0.472 and 0.532 mj/kgbw0.75/day for l, m and h respectively. a unit of change in bcs corresponded to 5.8 kg bw in adult pelibuey ewes. it was required 60 mj of me above maintenance to gain a kg of bw, indicating that a unit change in bcs may require 345 mj of me. our data suggest that mem may range from 0.481 to 0.529 mj/kgbw0.75/day, values higher than previously reported.