Processing and evaluation of nutritive value of fish silage for feeding Omani sheep

This study evaluated the potential of preparing fish silage (FS) as a low-cost, protein-rich supplement for livestock feeding in Oman from ground Indian oil sardines (Sardinella longiceps) using organic and inorganic acids. It was co-dried with wheat bran before being mixed with other feed ingredients and pelleted for feeding Omani sheep. Forty Omani sheep were offered one of five diets aiming to gradually replace soybean meal (SBM) with FS. The proportions of FS in the diet were 0, 50, 100, 150 and 200 g/kg, whereas the parallel SBM levels ranged from 17% to 0%. Animals were fed 500 g/d of the concentrates and allowed ad libitum access to Rhodes grass hay. A digestibility experiment was carried out on 12 sheep fed 0, 100 and 200 g/kg FS. The fresh FS dry matter (DM) was 393 g/kg and it contained 510 g/kg crude protein (CP), 220 g/kg ether extract (EE), 153 g/kg ash, 34 g/kg calcium (Ca) and 31 g/kg phosphorus on DM basis. The 75:25 silage:wheat bran mixture contained 883 g/kg DM and 390, 139, 120, 17, 17 g/kg DM CP, EE, ash, Ca and phosphorus, respectively. The FS amino acid contents were comparable to that of the SBM. No ill health signs were observed on experimental animals. There were no differences (P > 0.05) in digestibility coefficients of CP, acid detergent fibre and neutral detergent fibre between the 0, 100 and 200 g/kg FS diets. However, the 200 g/kg silage diet had lower (P < 0.001) DM, ash, Ca, P and energy digestibility coefficients. The study indicated that FS can successfully be made under Omani conditions and may be used as an excellent protein source for feeding sheep.