초록
The study was carried out to evaluate leucaena seeds as a protein replacement of mustard seed cake (MSC) in the concentrate mixture of growing lambs. Fifteen owing male lambs (Local${\times}$Corridale) with an average body weight of 16.3 kg were allocated into three dietary treatments (T1, T2, and T3) with five animals in each group. Animals were offered dry mixed grass, berseem hay and concentrate mixture to meet their nutrient requirements. In concentrate mixture of T1, (Control) MSC was used as protein source, while in T2 and T3 groups, 25 and 50% of MSC was replaced by leucaena leucocephala seeds. On completion of three months (90 days) of feeding, a digestion cum-metabolism trial was conducted to determine DMI, nutrient utilization, and nitrogen balance. Changes in body weight were recorded at 15 day internals and eating patterns were recorded for 3 consecutive days at the end of the feeding trial. MSC had higher CP contents than leucaena seeds (27.0%). Mimosine contents in leucaena seeds were 1.1 compared to 0.2 and 0.4% in concentrate mixture of T2 and T3 group, respectively. Dry matter intake varied non-significantly ($79.3{\pm}1.2$ to $83.4{\pm}1.3g/kg$ $w^{0.75}$) across the dietary treatments. Digestibility of DM and cell wall polysaccharides (NDF, ADF. Cellulose and hemicellulose) were comparable, however CP digestibility was relatively lower in leucaena luecocephala seeds based groups (T2 $45.5{\pm}1.7$ and T3 $46.7{\pm}3.5$) compared to MSC supplemented group (T1 $47.7{\pm}0.9%$). The growth rate of lambs was non-significantly higher in T1 ($79.2{\pm}5.4$) compared to T2 ($73.8{\pm}8.8$) and T3 ($73.9{\pm}7.0$), respectively. The animals were in positive nitrogen balance and N-balance varied from 1.8 to 2.9 g/d across treatment groups. The eating rate (% of total offered) of concentrate up-to 15 min was relatively higher in T1 (82.4) than T2 (74.2) and T3 (77.8%). However no effect of leucaena seeds was recorded on total DMI of animals. The results of the study revealed that the inclusion of up to 50% leucaena seeds, as protein source in concentrate mixture of lambs had no adverse effect on DMI, nutrient utilization, eating patterns, nitrogen balance and growth performance of lambs.