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Feed Intake, Weight Gain and Carcass Yield Characteristics of Intact Hararghe Highland Male Goats Fed on Different Hay to Concentrate Ratios
Feed intake, live weight gain and carcass yield characteristics were studied using twenty-five yearling intact Hararghe highland male goats (17.6 ± 0.11 kg body weight) fed diets containing different hay to concentrate ratios, viz., 100:0, 80:20, 70:30, 60:40 and 50:50% for T1, T2, T3, T4 and T5, respectively, in a randomized complete block design experiment with five animals per treatment that lasted for 90 days. The amount of CP supplied was 3.73, 10.15, 13.36, 16.57 and 19.79% per kg DM and the ME (MJ/kg DM) was
6.64, 7.51, 7.95, 8.38 and 8.82 for the respective treatments. Dry matter and nutrient intakes were measured daily, while live weight gain and feed conversion efficiency were recorded at the weekly interval. At the end of the feeding trial, all goats from each treatment were fasted for 12 h and slaughtered after taking the slaughter weight of each goat. Measurements were also taken on empty body weight, hot carcass weight,
dressing percentage (DP) and rib eye muscle area. Concentrate supplementation of goats resulted in high (P < 0.05) dry matter, crude protein and metabolizable energy intake, which was reflected in increased (P < 0.05) average daily weight gain (ADWG) and feed conversion efficiency (FCE). The empty body weight, hot carcass weight, DP and rib eye muscle area were higher (P < 0.05) for concentrate supplemented groups
compared to those fed on hay alone. Goats on equal hay to concentrate ratio (T5) had higher empty body weight, hot carcass weight and rib eye muscle area when compared to those on T2 and T3. Different proportions of hay to concentrate did not affect the DP, but carcasses dressed from goats offered with concentrate feeds had higher (P < 0.05) percentages of lean and boneless meat, and lean: bone and lean + fat:
bone ratios, but lower percentage of bone than the carcasses from goats fed hay alone. The percentage of boneless meat was similar between goats on T2, T4 and T5, while the percentage of total edible offal components was similar between supplemented and un-supplemented groups. The proportion of the gut content and total non-edible offal components decreased with the increasing concentrate level, while the
percentage of the total saleable components increased. Correlation and regression analysis revealed a positive and significant (P < 0.01) relationship between dry matter intake (r = 0.67), slaughter weight (r = 0.89), hot carcass weight (r = 0.90), dressing percentage (r = 0.70), lean meat (r = 0.95) and rib-eye muscle area (r = 0.92) with the level of concentrate supplementation. However, there was a non-significant (P > 0.05) weak
negative correlation (r = -0.16) between ADWG and the level of concentrate supplementation. Considering ADWG, FCE, DP and percentage of boneless meat, the diet with 20% concentrate level could be recommended for optimum live weight gain, feed conversion efficiency and carcass yield characteristics of goats.
Keywords: Body Weight Gain; Carcass Yield; Feed Intake; Hararghe Highland Goats; Hay to Concentrate Ratio
East African Journal of Sciences Vol. 1 (1) 2007: pp. 45-54
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