Tick susceptibility and its effects on growth performance and carcass characteristics of Nguni, Bonsmara and Angus steers raised on natural pasture
Tick susceptibility and its effects on growth performance and carcass characteristics of Nguni, Bonsmara and Angus steers raised on natural pasture
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DOI：
10.1017/s1751731107001036
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发表时间：
2008-02-01
期刊：
影响因子：
3.6
通讯作者：
Strydom, P. E.
中科院分区：
文献类型：
--
作者：
Muchenje, V.;Dzama, K.;Strydom, P. E.
本研究的目的是比较在天然牧场上饲养的恩古尼、邦斯马拉和安格斯牛浸泡和未浸泡的扁虱数量、生长和屠体特性。100只7个月大的被阉割的断奶婴儿在黑尔堡大学农场被饲养了12个月。安格斯和邦斯马拉各有30只断奶仔猪，恩古尼品种有40只断奶仔猪。每两周就有一半的宝斯拉、安格斯和14只恩古尼断奶婴儿被浸泡一次。其余的没有浸泡过。记录月度体重和尾巴、阴囊、腹部、胸骨和耳朵上的扁虱计数。浸泡过的恩古尼牛的扁虱数量最低(P<；0.05)，而未浸泡的安格斯牛的扁虱数量最高(P<；0.05)。暖湿季节比凉爽干燥季节有更多的扁虱(P<；0.05)。其中以耳为最高(P<；0.05)。三个品种的平均日增重相似(P>；0.05)。未浸泡的宝斯拉肉牛的屠体(P<；0.05)最重(142+/-5.4)，而未浸泡的恩古尼肉牛的屠体最轻(111+/-4.5千克)。未浸泡的宝宝鱼的眼肌面积最大(P<；0.05)，眼肌面积为3996±/-120.8 mm(2)，而未浸泡的安格斯的眼肌面积最小(3291±210.6 mm(2))。未浸泡的肉牛屠宰率最高(P<；0.05)，屠宰率为53.8±-1.01，而未浸泡的恩古尼肉鸡的屠宰率最低(50.3+/-0.84)。目前的研究表明，尽管未浸泡的牛比浸渍的牛有更高的扁虱负荷(P<；0.05)，但它们的生长和屠体特征相似(P>；0.05)。研究还表明，尽管恩古尼牛是一种体型较小的品种，但它的日增重与体型较大的宝斯拉和安格斯牛相似(P&gT；0.05)。因此，恩古尼牛具有生产有机牛肉的潜力，然而，要合理评估恩古尼牛的有机牛肉生产潜力，需要评估其在天然牧场下的肉质特性。
The objective of the current study was to compare tick loads, growth and carcass characteristics of dipped and non-dipped Nguni, Bonsmara and Angus steers raised on natural pasture. One hundred 7-month-old castrated weaners were kept at the University of Fort Hare Farm for 12 months. There were 30 weaners each of Angus and Bonsmara, and 40 weaners of the Nguni breed. Half the Bonsmara, Angus and 14 Nguni weaners were dipped every fortnight. The rest were not dipped. Monthly weights and tick counts under the tail, on scrotum, belly, sternum and ears of the steers were recorded. The dipped Nguni steers had lowest (P < 0.05) tick counts, and the non-dipped Angus steers had the highest (P < 0.05) tick counts. There were more ticks (P < 0.05) during the warm wet season than during the cool dry season. Ears had the highest (P < 0.05) tick infestation. Average daily gain (ADG) was similar (P > 0.05) among the three breeds. The non-dipped Bonsmara steers had the heaviest (P < 0.05) carcasses (142 +/- 5.4) while the non-dipped Nguni steers had the lightest (P < 0.05) carcasses (111 +/- 4.5 kg). The non-dipped Bonsmara had the highest (P < 0.05) eye muscle area (3996 +/- 120.8 mm(2)) while the non-dipped Angus had the smallest (P < 0.05) eye muscle area (3291 +/- 210.6 mm(2)). The non-dipped Bonsmara also had the highest (P < 0.05) dressing percentage (53.8 +/- 1.01) while the non-dipped Nguni had the lowest (P < 0.05) dressing percentage (50.3 +/- 0.84). The current study has shown that while the non-dipped steers had higher (P < 0.05) tick loads than the dipped steers, their growth and carcass characteristics were similar (P > 0.05). The study has also shown that, despite being a small-framed breed, the Nguni steers had similar (P > 0.05) ADG to the large-framed Bonsmara and Angus steers. Therefore, the Nguni cattle have the potential to produce organic beef However, a reasonable assessment of organic beef production potential of the Nguni requires an evaluation of its meat quality traits under natural pasture.