Abstract
This study investigated the feed intake, and energy and nitrogen partition of growing lambs fed on diet with fish silage (FS) as a major protein supplement. The FS was compared with the conventional protein feeds like fish meal (FM) and urea (UR). Six castrated and 6 female Suffolk lambs were divided into three groups and fed on Italian ryegrass silage (IRS) as basal ration at 70% on dry matter (DM) basis. The protein based concentrate mixture of FS, FM or UR was supplemented to one of the three groups at 30% DM. The DM intake of animals was not affected by FS diet and was comparable with the other diets. Likewise, the organic matter intake and digestible organic matter intake (DOMI) of the animals were unaffected by the varying protein supplements. The nitrogen retention of FS group was 37% higher than that of the UR group, however, the FM group was significantly higher than the UR group (P⟨0.05). The retained energy of FS group with 116.6kJ/kg W0.75/d tended to decline compared to the other groups. The methane energy and methane production of the FS group which were 79.1kJ/kgW0.75/d and 55.6 L/kg DOMI, respectively, had a lower tendency while the heat production with 13.2MJ/kg DOMI tended to increase compared to the other treatments. The respiratory quotient of the FS group with 1.09 tended to be lower than the other groups. These results suggest the potential of fish silage as a major protein supplement but further investigation is needed to upgrade the palatability and nutritional value.
