Growth performance of Red Sokoto bucks fed diets containing varying inclusion levels of irrigated gamba grass (Andropogon gayanus) forage in Zaria
A study was carried out to evaluate the effect of feeding graded levels of Gamba grass (Andropogon gayanus) forage on the performance of Red Sokoto bucks. Twelve (12) Red Sokoto bucks were randomly allotted into four (4) treatment diets containing graded levels of Gamba grass forage (0, 25, 50, and 100%). Experimental animals were individually pen-fed at 3% body weight in a Completely Randomized Design (CBD) for a period of 3 months. Animals fed 50% inclusion level of gamba grass forage in the diet had higher (P < 0.05) final live weight gain (13.50kg), average daily weight gain (38.89g/day) and daily feed intake, (371.30g/day). The live weight gain of bucks in the supplemented diets (25, 50 and 75) were significantly (P < 0.05) higher (2.22, 3.50, 2.80 kg) respectively than the un-supplemented diet (2.73kg). Results indicated that digestibility of dry matter (93.84%), crude protein (95.76%), crude fiber (97.07%), nitrogen free extract, (92.26%) and ash (94.60%) increased (P < 0.05) with increasing level of gamba grass forage in the diet. Also, bucks fed dietary inclusion level of 50% Andropogon gayanus Forage had significantly higher (P < 0.05) nitrogen intake (47.33 g/day), although it was at par with the control (41.32g/day) diet. Total Nitrogen output was higher (P < 0.05) in bucks fed the control diet and 50% inclusion level of gamba grass (5.85 vs 6.38g/day). Nitrogen absorbed and retained were higher (P < 0.05) in bucks fed 50% inclusion levels of gamba grass. However, nitrogen retained as percentage of intake was not significant (P > 0.05) across the treatments. The pH and temperature of rumen fluid of bucks fed 75% inclusion level of gamba grass forage were higher (P < 0.05) than other treatments fed. Total Volatile Fatty Acid (TVFA) of bucks fed 75% inclusion level gamba grass was 18% lower (P < 0.05) than those control diet. It was therefore concluded, that supplementation of 50% gamba grass forage to Red Sokoto bucks improved the dry matter intake, nutrient digestibility and live weight gain compared to the un-supplemented diet. Therefore, it is recommended that gamba grass forage should be supplemented to Red Sokoto bucks up to 50% without any negative effect on their performance.
Keywords: Gamba grass, growth performance, nutrient utilization, red sokoto buck