Welday Kiflay, Abegaz Solomon, Urge Mengistu, Abebe Ayele, Mezgebe Gebretensae
Department of Animal and Range Sciences, Jigjiga University, Jigjiga, Ethiopia.
Ethiopian Institute of Agricultural Research (EIAR), Addis Ababa, Ethiopia.
J Anim Breed Genet. 2022 Nov;139(6):623-633. doi: 10.1111/jbg.12736. Epub 2022 Aug 12.
A sound breeding objective is a basis for genetic improvement in the overall economic merit of farm animals. This study aimed to define smallholders' sheep breeding objectives using a conjoint-based choice experiment and bio-economic model. Multinomial logistic regression analysis showed differences (p < 0.001) among the derived weights allocated by farmers to body size, twining rate, mothering ability, libido, tail type, colour and lambing interval which formed the high priority traits. The likelihood values of farmer's top three preferred traits for ram were body size (0.659 ± 0.009), tail type (0.325 ± 0.016) and libido (0.247 ± 0.016) while body size (0.459 ± 0.010), twining rate (0.313 ± 0.010) and mothering ability (0.261 ± 0.010) were more preferred traits for selection of breeding ewes. Conjoint-based choice experiment and bio-economic model indicated that live body weight at 6 months of age, twining rate (litter size) and mothering ability (preweaning lamb survival) were the most economically important traits of the breeding ewes. A genetic improvement by one genetic standard deviation (σ ) in these traits resulted in a profit of Ethiopian Birr 36.03-60.47/ewe/year. A fair correlation (r = 0.63) was observed between farmers' traits preference (conjoint-based choice card experiment) and the estimated economic value of traits indicating a good relationship between farmers' preferences for traits and economic values of the traits. This would indicate that weighting traits in selection indexes with farmers' trait selection using a conjoint-based choice experiment would direct genetic improvement towards desired profitability. Moreover, the fair correspondence between the two methods suggests that bio-economic modelling, if designed properly considering farmers' concerns, could be used to reflect farmers' breeding objectives. Therefore, for reasonable genetic progress and sheep flock profitability, more attention should be given to litter size, preweaning lamb survival and body weight at 6 months of age as they are preferred by farmers and their economic weights. Further, research on the modalities for complementary use of the two methods to define breeding objectives under smallholder conditions is warranted.
一个合理的育种目标是家畜总体经济价值遗传改良的基础。本研究旨在通过基于联合分析的选择试验和生物经济模型来确定小农户的绵羊育种目标。多项逻辑回归分析表明，农民赋予体型、产羔率、母性能力、性欲、尾巴类型、毛色和产羔间隔的权重存在差异（p < 0.001），这些构成了高优先级性状。农民对公羊的前三个偏好性状的似然值分别为体型（0.659 ± 0.009）、尾巴类型（0.325 ± 0.016）和性欲（0.247 ± 0.016），而对于繁殖母羊的选择，体型（0.459 ± 0.010）、产羔率（0.313 ± 0.010）和母性能力（0.261 ± 0.010）是更受偏好的性状。基于联合分析的选择试验和生物经济模型表明，6月龄活体重、产羔率（窝产仔数）和母性能力（断奶前羔羊存活率）是繁殖母羊最重要的经济性状。这些性状每提高一个遗传标准差（σ），每只母羊每年可带来36.03 - 60.47埃塞俄比亚比尔的利润。观察到农民的性状偏好（基于联合分析的选择卡试验）与性状的估计经济价值之间存在显著相关性（r = 0.63），表明农民对性状的偏好与性状的经济价值之间存在良好的关系。这表明，在选择指数中根据农民使用基于联合分析的选择试验的性状选择对性状进行加权，将使遗传改良朝着期望的盈利能力方向发展。此外，这两种方法之间的显著对应关系表明，如果在设计生物经济模型时适当考虑农民的关注点，就可以用来反映农民的育种目标。因此，为了实现合理的遗传进展和羊群盈利能力，应更多关注窝产仔数、断奶前羔羊存活率和6月龄体重，因为它们是农民所偏好的且具有经济权重。此外，有必要研究在小农户条件下互补使用这两种方法来确定育种目标的方式。
