The effect of dietary energy level of finishing goats [Sudan]

Thirty six entire desert male kids, divided randomly into three groups A, B and C in a complete randomized design, were involved in this study. The kids were kept for a pre-experimental period of a month during which they were fed molasses concentrate (52 molasses, 39 wheat bran, 5 groundnut cakes, 3 urea and 1 common salt) plus sorghum straw basal diet. Group A was fed the high dietary energy level (12.2 MJ/kg DM), group B offered the medium energy level (10.3 MJ) while group C offered the low energy diet (8 MJ/kg DM). Green fodder (Medicago sativa) was offered at a rate of half kilogram twice a week/head. The overall rate of weight gain were 0.48 kg per week, 0.38 kg and 0.024 kg for high, medium and low dietary energy levels respectively. The difference was significant (P0.001). Kids fed on high and medium dietary energy levels ate 7.6 and 11.95 kg dry matter to obtain one kilogram liveweight gain compared to 24.06 for the low dietary energy level. The difference in feed conversion rate was significant. The dietary energy level produced significant effect on dressing percentage on both full and empty body weight basis. The values on hot basis were 50.42, 48.7 and 44.16 on full basis, and 55.15, 54.66 and 51.4 on empty basis for high, medium and low dietary levels, respectively. The dietary energy level also produced significant (P0.01) effect on the muscular tissue percentage which was levels. The total bone percentage was significantly (P0.001) higher in the low energy diet. The high and medium dietary energy tended to deposit more fat in their carcass 8.2 and 6.99 respectively compared to 3.79 of low dietary energy level. Muscle: bone ratio was significantly higher in high (2.69) and medium (2.59) compared to 1.93 for low dietary energy. Dissection of commercial joints indicated that high and medium dietary energy levels had significantly more muscle, less bone and significantly higher percentage of fat compared to the low dietary energy. Meat chemical composition of the three ditary energy treatmentshowed that the fat percentage was higher in high and medium energy dietary energy level, the ash content was significantly (P0.001) high in the low dietary energy. The sarcoplasmic and myofibrillar protein percentage were affected significantly (P0.001) by the dietary energy and higher in the high and medium energy level compared to the low energy level. The dietary energy level affected the Hunter colour components of the meat, redness (a) significantly (P0.001) and yellowness (b) (P0.05). Although the water holding capacity and cooking loss percentage were not significant, but lower value were observed to the high and medium dietary energy compared to low level. Shear force was significantly (P0.01) effected by dietary energy level. Higher values of shear force and connective tissue strength were observed in the meat of low dietary energy level compared to the high and medium levels