Effect of substitution of sorghum stover with sugarcane top silage on ruminal dry matter degradability of diets and growth performance of feedlot hair lambs

Abstract

The substitution of sorghum stover with sugarcane top silage [0 (T1), 5 (T2) and 10% (T3) DM] in high concentrate diets for feedlot hair lambs was evaluated in two experiments. In experiment one, ruminal dry matter degradability (RDMD) was evaluated in three ruminally cannulated 6-month-old Pelibuey sheep in a 3×3 Latin square design. The RDMD was determined by the nylon bag technique at incubation times of 4, 8, 12, 24, 48 and 72h. There was no effect of diet (P>0.05) for the rapidly degraded (a) or degradable fraction (b) of dry matter. The maximum degradability (a+b) was greater for T3 than T1 (P<0.05); T2 was similar to T1 and T3 (P>0.05). Effective degradability at 6% h−1 of ruminal turnover (k) was lower for T2 (P<0.05) than for T1 and T3; ruminal turnover was higher (P>0.05) for T1 than for T3. Growth performance of feedlot hair lambs was evaluated in a second experiment using the same diets as in experiment one. Twenty-seven 5-month-old intact crossbred male hair lambs (19.04±1.56kg) were assigned at random to 9 pens (3 lambs per pen). The feeding trial lasted for 63days. Feed intake decreased (P<0.05) with increasing level of sugarcane tops silage in diet. Nevertheless daily weight gain was not affected by diet. There was no treatment effect (P>0.05) on feed efficiency (gain/feed intake). It is concluded that ensiled sugarcane tops is a practical alternative to substitute for sorghum stover in diets for growing finishing feedlot lambs. Partial replacement of sorghum stover with ensiled sugar tops does not negatively affect daily weight gain.