Dietary Supplementation with Spring Onion on Growth, Nutrient Utilization, Economic Analyses and In Vitro Methane Emissions in West African Dwarf Goats
The study was conducted to determine the effect of dietary supplementation with spring onion on growth, nutrient utilization, economic analyses and in vitro methane emissions in West African dwarf goats. Two hundred and forty West African dwarf male goats aged between 7 to 8 months old with initial average live body weight of 7.00 ± 0.08kg were used for the study. They were randomly allotted to four dietary treatments with sixty goats per treatment in a completely randomized design. The prepared experimental diets that were received by goats contained ED1 (60% guinea grass with no spring onion as the control group), ED2 (59% guinea grass with 1% spring onion), ED3 (58% guinea grass with 2% spring onion) and ED4 (57% guinea grass with 3% spring onion). Firstly, the evaluation comprised in vitro study of methane gas production and then followed by in vivo study of growth, nutrient utilization and economic analysis of goats. In all the diets examined, results showed that in vitro ammonia nitrogen concentration(12.04 mg/100ml), total volatile fatty acids(4.01 mmol), acetate (64.93 mol/100mol), butyrate (12.09 mol/100mol), methane (71.22 mL/gDM), fractional rate of gas production(0.079h-1), average gas production rate(3.04Ml/h), daily feed intake (256.29g/day), feed conversion ratio (6.15), digestibility of ether extract (65.05%), ash (68.01%), faecal with urinary nitrogen output(2.98 and 1.72g/day), total nitrogen output (4.78g/day) and total cost in naira (125,400) were significantly (p<0.05) higher in diet ED1 than diets ED2, ED3 and ED4. Goats on diet ED4 were significantly (p<0.05) improved in propionate ( 25.67 mol/100mol), methane/total volatile fatty acids ratio (22.23), effective dry matter degradability(60.21g/kg), true dry matter degradability(74.52g/kg), final body weight(11.96kg), total with daily weight gain 4.99kg and 71.29g), digestibility of dry matter(72.43%), crude protein (70.86%), crude fibre (71.02%), nitrogen free extract(70.17%), neutral and acid detergent fibre(69.86 and 66.21%), nitrogen intake (11.05g/day), nitrogen balance and retained (8.08 and 0.73g/day), nitrogen retention % intake (73.12%), total revenue in naria (263, 270) and net profit in naria (169,020) than those on other diets. Meanwhile, no significant differences (p>0.05) were found in rumen pH, acetate/propionate ratio, iso-butyrate, valerate, iso-valerate, asymptotic gas production and initial body weight among treatments. It can be concluded that inclusion levels of 3 and 4% spring onion as supplement to 58 and 57% guinea grass with 40% concentrate diet (ED3 and ED4) improved performance of goats and suppressed in-vitro methane gas with cost reduction that resulted in higher net profit.