Effect of concentrate supplementation on foraging behavior and finishing performance of grazing meat goats in Uganda
This study established the effect of graded levels of concentrate supplement and period of feeding on grazing behavior, growth and slaughter characteristics of meat goats. The study also assessed the profitability of supplementing grazing meat goats using gross margins and financial efficiency. One hundred forty four castrated Mubende-Boer crossbreds with an average initial weight of 25±3kg, were randomly allocated to 4 dietary treatments that included solely grazing with no supplement as control, plus either 200, 400 or 600 grams of dry matter per day (g DM/Day) of concentrate supplement. The goats were kept on the allotted dietary treatments for either 60, 90 or 120 days in a 4x3 factorial treatment structure, after which they were slaughtered for carcass and non-carcass evaluation. Gross margins analysis was used as the measure of profitability. There were no significant interaction effects (P>0.05) between level and duration of feeding and the duration of feeding did not (p>0.05) affect the grazing behavior. Significant linear effects (P=0.001) were exhibited for graded levels of concentrate supplementation on meat goats for all behavioral parameters that were measured. Significant quadratic relationships for percentage time spent on grazing and browsing (P=0.001), standing and ruminating (p=0.0015), playing (P=0.0001) and lying and ruminating (P=0.0007) were exhibited for the effect of graded levels of concentrate. The highest proportion of daily activity time was exhibited for grazing and browsing for all concentrate treatment levels and was maximum (76.8%) for concentrate level of 200g DM/day. The maximum (P<0.05) grazing intake (604g DM / day) was observed in goats fed 200g DM/day for 90 days of feeding while goats fed 600g DM/day and kept for a 60 day feeding period, had the least (P<0.05) grazing intake (290g DM/day). Total DM intake was highest (P<0.05) with goats fed 600g DM/day and kept on pastures for 120 days but was lowest (P<0.05) with control goats that were kept for 120days on pastures. Efficiency of feed utilization was highest (FCR = 8.9; P<0.05) in goats fed 600g DM/day and kept for 90 days on pastures and lowest (FCR = 74; P<0.05) for non-supplemented goats that grazed pastures for a period of 90 days. The stomach and total gut fill reduced (P<0.05) with the length of feeding period, in which it was observed that non-supplemented goats kept on pastures for 60days registered the highest stomach and total gut fill while those supplemented with 600g DM/Day of concentrate for a period of 120 days registered the least amounts for both parameters. There were no effects (P>0.005) of interaction between amount of concentrate offered and length of feeding period on the size of prime cuts measured. However, the size of breast and flap, fore quarter and loin area increased (P<0.005) with increasing feeding period. The highest returns to investment in supplementation (TR:TVC ratio) of fattening meat goats was obtained for goats supplemented with 200g DM/day of concentrate for a fattening period of 90 days and goats supplemented with 600g DM/day of concentrate for a period of 60 days. However, goats supplemented with 200g DM/day of concentrate for a fattening period of 90 days had significantly lower daily weight gain (66g/day) than goats supplemented with 600g DM/day of concentrate for a period of 60 days (116g/day). Regression analysis revealed that the biological optimum level of supplementation of grazing goats should be at 651.25g DM/day of concentrate intake and fattened for 55 days for optimum body weight gain, carcass composition and meat yield. This level of supplementation corresponded to a total dry matter intake of 887.47gDM, FCR of 36.78 and a daily gain of 279g. However, analysis of profitability indicated that grazing meat goats should be supplemented with concentrate at a level of 600g DM/Day intake and fattened for 60 days to maximize the economic efficiency of the enterprise. This study indicated that a high potential lies in the utilization of Agro-Industrial bi-products as a strategy for better feeding management to improve meat production in Uganda. This was evidenced by the improved performance of grazing goats supplemented using the by-products. It was therefore concluded that free-ranging meat goats should be supplemented for optimum body weight gain, carcass and non-carcass composition, meat yield and enterprise profitability. However, the financial efficiency results indicated that although the gross margins per goat for the supplemented group were relatively higher than non-supplemented, the TR/TVC ratios did not differ much. This was attributed to high variable costs incurred on concentrate supplement feed ingredients and non-payment of premium price of quality meat in Uganda. The ratio of 1.8 for the non-supplemented goats was good enough given the low level of inputs. A ratio of about 1.5 would be desirable for the non-supplemented goats if goat producers are to improve their business sustainably. This could be the reason why goat production in Uganda is still a viable business among goat producers despite their non-investment into aspects like improved feeding technologies for improved productivity.