Hozza W A, Mtenga L A, Kifaro G C, Shija D S N, Mushi D E, Safari J G, Shirima E J M
Institute of Rural Development Planning, Dodoma, 41000 Tanzania .
Ministry of Livestock and Fisheries Development, Dar-es-Salaam 11000, Tanzania .
Asian-Australas J Anim Sci. 2014 Dec;27(12):1773-82. doi: 10.5713/ajas.2014.14069.
The aim of the experiment was to study the effect of feeding system on meat quality characteristics of Small East African (SEA) goats and their crosses with Norwegian (SEA×N) goats finished under small scale farming conditions. Twenty four castrated goats at the age of 18 months with live body weight of 16.7±0.54 kg from each breed (SEA and SEA×N) were distributed in a completely randomized design in a 2×3 factorial arrangement (two breed, and three dietary treatments). The dietary treatments were; no access to concentrate (T0), 66% access to ad libitum concentrate allowance (T66) and 100% access to ad libitum concentrate allowance with 20% refusal (T100) and the experimental period was for 84 days. In addition, all goats were allowed to graze for 2 hours daily and later fed grass hay on ad libitum basis. Daily feed intakes were recorded for all 84-days of experiment after which the animals were slaughtered. Feed intake of T100 animals was 536 g/d, which was 183 g/d higher than that of T66 group. Supplemented goats had significantly (p<0.05) better feed conversion efficiency. The SEA had higher (p<0.05) hot carcass weight (8.2 vs 7.9 kg), true dressing percentage (54.5 vs 53.3) and commercial dressing percentage (43.3 vs 41.6) compared to SEA×N. There was no significant difference (p>0.05) for dressing percentage and carcass conformation among supplemented goats except fatness score, total fat depots and carcass fat which increased (p<0.05) with increasing concentrate levels in the diet. Increasing level of concentrate on offer increased meat dry matter with subsequent increase of fat in the meat. Muscle pH of goats fed concentrate declined rapidly and reached below 6 at 6 h post-mortem but temperature remained at 28°C. Cooking loss and meat tenderness improved (p<0.05) and thawing loss increased (p<0.05) with ageing period. Similarly, meat tenderness improved (p<0.05) with concentrate supplementation. Shear force of muscles varied from 36 to 66, the high values been associated with Semimembranosus and Gluteobiceps muscles. The present study demonstrates that there are differences in meat quality characteristics of meat from SEA goats and their crosses with Norwegian breeds finished under small scale farming conditions in rural areas. Therefore, concentrate supplementation of goats of both breeds improves meat quality attributes.
该实验的目的是研究饲养系统对东非小山羊(SEA)及其与挪威山羊杂交后代(SEA×N)在小规模养殖条件下育肥后肉质特性的影响。从每个品种(SEA和SEA×N)选取24只18月龄、体重16.7±0.54千克的去势山羊,按照完全随机设计,采用2×3析因排列方式(两个品种,三种日粮处理)进行分组。日粮处理分别为:不提供精饲料(T0)、66%自由采食精饲料量(T66)和100%自由采食精饲料量且有20%剩余(T100),实验期为84天。此外,所有山羊每天允许放牧2小时,之后自由采食禾本科干草。在为期84天的实验期间记录所有山羊的日采食量,之后将动物屠宰。T100组动物的采食量为536克/天,比T66组高183克/天。补饲山羊的饲料转化效率显著更高(p<0.05)。与SEA×N相比,SEA的热胴体重更高(8.2千克对7.9千克,p<0.05),真宰率更高(54.5%对53.3%),商业宰率更高(43.3%对41.6%)。在补饲山羊中,除了脂肪评分、总脂肪沉积量和胴体脂肪随日粮中精饲料水平增加而增加(p<0.05)外,宰率和胴体形态没有显著差异(p>0.05)。提供的精饲料水平增加会使肉的干物质增加,随后肉中的脂肪也会增加。采食精饲料的山羊肌肉pH值在宰后6小时迅速下降并低于6,但温度保持在28°C。随着成熟时间延长,蒸煮损失和肉嫩度得到改善(p<0.05),解冻损失增加(p<0.05)。同样,补饲精饲料也使肉嫩度得到改善(p<0.05)。肌肉剪切力在36至66之间变化,较高的值与半膜肌和臀二头肌有关。本研究表明,在农村小规模养殖条件下育肥的东非小山羊及其与挪威品种杂交后代的肉,在肉质特性上存在差异。因此,对两个品种的山羊补饲精饲料可改善肉质特性。