Effect of orange pulp fermented in solid substrate with Saccharomyces cerevisiae in diets, on productive behavior of confined lambs

The effect on growth performance of diets containing orange pulp fermented in solid substrate with the yeast Saccharomyces cerevisiae (S. cerevisiae) was evaluated in feedlot lambs. Fifteen non-castrated male lambs (Pelibuey x Dorper) with an initial weight of 22 ± 4 kg were distributed in individual pens in a completely randomized design. The feeding trial lasted 60 days. Treatments were: treatment 1 (T1), 50% commercial feed plus 50% wet basis (WB) of orange pulp fermented with yeast; treatment 2 (T2), 50% commercial feed plus 50% (WB) fresh orange pulp without yeast; and treatment 3 (T3) 100% commercial feed as a total mixed ration. The variables of the study were: average daily weight gain, feed consumption, feed conversion ratio, area of Longissimus dorsi and back fat thickness, the latter two measured at the end of the test using ultrasound. Daily weight gain was significantly lower (P<0.05) in lambs of T2 compared with those of T1 and T3 which had similar (P>0.05) weight gain; average daily gain (ADG) for T1, T2 and T3 was 0.270±0.027, 0.200±0.035 and 0.273±0.038 kg/d, respectively. Feed conversion ratio (feed consumed/weight gain) of lambs in T2 presented worth value (P <0.05) than those of T1 and T3. There was no difference in Longissimus dorsi area or back-fat thickness (P>0.05). In conclusion, substituting orange pulp fermented in solid state with S. cerevisiae for 50% of a commercial diet resulted in similar productive behavior of confined sheep, whereas substitution with non-fermented orange pulp may reduce growth performance of lambs.