University of Khartoum

Effect of Dietary Energy Level on Growth and Carcass Characteristics of Sudan Nubian Goats

Effect of Dietary Energy Level on Growth and Carcass Characteristics of Sudan Nubian Goats

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Title: Effect of Dietary Energy Level on Growth and Carcass Characteristics of Sudan Nubian Goats
Author: Magboul, Yagoub
Abstract: Effect of dietary energy level on female goat kid growth and carcass characteristics: The present study was conducted to evaluate the effect of different dietary energy levels on performance and carcass characteristics of female goat kids. Graded proportions of dietary energy (8.5, 9.5, 10.5 and 11.5 MjME/kg) were incorporated in four iso-nitrogenous diets for the experiment. Sixty yearling female goat kids of Nubian ecotype with an average initial weight of 16.54 kg, were used. These kids were divided randomly into 4 groups A, B, C and D in a complete randomized design. Group A was fed the highest dietary energy level (11.5 MjME/kg) followed by group B (10.5 MjME/kg), group C (9.5 MjME/kg) and group D which was offered the lowest dietary energy level (8.5 MjME/kg). The goat kid groups were fed these diets for 105 days. The dietary energy level had a significant effect on body and carcass measurements, where group D which was raised on the lowest dietary energy level had the lowest values of body measurements while group A had the highest body measurements. Total gain was 9.12, 7.81, 4.75 and 0.35 Kg/head for group A, B, C and D respectively, which was highly significant (P< 0.001). The weekly and daily rate of weight gain and feed conversion ratio were also significantly higher in the goat kid group A that was raised on the highest level of dietary energy. Dietary energy level produced significant effect on carcass characteristics as well as hot and cold dressing percentages. Dietary energy level also produced significant effects on total carcass bone and trim tissues which tended to increase with the decrease of dietary energy level. Total carcass fat was significantly decreased as the dietary energy level decreased. The effect of dietary energy level was clearly shown in fat distributed throughout the body of the goat kid. Total body, carcass and visceral fat were significantly (P< 0.01) decreased with the decrease of dietary energy level. Generally all non-carcass components weights were significantly affected by the level of dietary energy. These components tended to decrease in weight with the decrease of dietary energy level. Yield of wholesale cuts was not significantly affected by the level of dietary energy level, except the breast joint which was lower in group D which was raised on the lowest dietary energy level. Meat chemical composition was significantly (p<0.001) affected by the level of dietary energy. Meat moisture and protein content increased, while fat decreased with the decrease of dietary energy level. Meat quality attributes showed significant effect for water holding capacity and cooking loss, indicating that group A which was raised on the highest dietary energy level had superior water holding capacity and lower cooking loss. Meat colour revealed significant (P< 0.01) effect among the dietary treatments for lightness and redness, indicating that meat from group D which was raised on the lowest dietary energy level was darker red in colour than the meat from the other treatment groups. The meat from goats of group A which received the highest dietary energy level was the most tender compared with that from the other treatment groups. The dietary energy levels induced significant (P< 0.01, P< 0.05) effects among the tested groups for taste panel scores of flavour, tenderness and overall acceptability. Meat from female goats of group A which was raised on the highest dietary energy was most tender and acceptable than that from the other treatment groups. Exp. II Effect of rehabilitation of underfed female goat kids on growth and carcass characteristics: Seven kids from group D in the first experiment which were raised on the lowest dietary energy level (8.5 MjME/kg) were used to study the effect of rehabilitation on performance and carcass characteristics of the female goat kids. These kids were found to maintain their initial body weight throughout the feeding period which lasted for 105 days. These goat kids were rehabilitated on the high energy diet (11.5 MjME/kg) that was offered to group A and were kept until they reached the body weight attained by group A. They took 175 days to reach that weight. Rehabilitation had significant (P< 0.001) effect on weekly, daily rate of gains and total dry matter intake which were lower in the compensating female goats than the basal group. Dressing percentage increased significantly (P< 0.05) in the rehabilitated group. However carcass characteristics were not affected by rehabilitation. Carcass fat, bone and muscles were increased in the compensating group. Gut fill was slightly decreased in the rehabilitated group. Rehabilitation did not significantly affect fat distribution throughout the body, but total body, carcass and visceral fat were increased in the rehabilitation group. All non carcass components were not affected by the rehabilitation except the liver which was significantly (P< 0.05) increased and the udder which was significantly (P< 0.05) decreased in the rehabilitated group. Meat chemical composition was significantly affected by rehabilitation. Percentages of fat, sacroplasmic and Myofibrillar proteins increased significantly (P< 0.01) in the meat from the compensating goats. Moisture, ash, non-protein nitrogen percentages and pH values decreased but not significantly so in the meat from the rehabilitated goat group. Meat from the rehabilitated goat group showed superior water hold capacity and less cooking loss value. Meat from goats that experienced rehabilitation was significantly lighter in colour possibly due to increased fatness. However redness values of the meat, though not significant were lower compared with that from normally growing goat kids. Carcass measurements as heart girth and abdomen circumference were significantly (P< 0.05) increased by rehabilitation, while measurements, as body length and scapular and thigh circumference were not significantly affected. Taste panel scores for meat quality revealed that the rehabilitated goat group had significantly (p<0.01) less odour intensity, less tender meat and less meat colour values than the basal group. While juiciness scores were significantly (p<0.05) increased in the meat from the rehabilitated goat group.
URI: http://hdl.handle.net/123456789/8015
Date: 2015-04-01


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