Abebe Abiy Shenkut, Alemayehu Kefyalew, Gizaw Solomon
Department of Animal Science, Debre Tabor University, Debre Tabor, Ethiopia.
Department of Animal Science, Bahir Dar University, Bahir Dar, Ethiopia.
PLoS One. 2025 Sep 5;20(9):e0331701. doi: 10.1371/journal.pone.0331701. eCollection 2025.
Designing and implementing a sound breeding program is essential for sustainably improving livestock productivity. This study evaluated the efficiencies of three breeding schemes for sustainable genetic improvement of indigenous sheep in low-input production systems. The schemes were one-stage selection at six months (Scheme I) or yearling age (Scheme II) and two-stage selections with the first at six months and the second at the yearling age (Scheme III). Each scheme was assessed with three levels of selection proportions (5%, 10% and 20%) and four flock sizes (600, 1200, 1800 and 2400 breeding ewes). Selection responses were simulated using a deterministic approach employed in the SelAction software. For six-month weight, the annual predicted genetic gains ranged from 0.177 to 0.267 kg (Scheme I) and 0.157 to 0.233 kg (Scheme III). For yearling weight, simulated annual genetic gains were 0.268 to 0.399 kg (Scheme II) and 0.265 to 0.398 kg (Scheme III). The expected annual genetic gains for the number of lambs weaned per ewe bred (NLW) and fertility rate were generally small, but the estimates in Schemes II and III were higher compared to Scheme I. The annual economic responses estimated for Schemes I, II, and III ranged from US$0.393 to 0.591, 0.589 to 0.879 and 0.494 to 0.744, respectively. Notably, Scheme II yielded 34% and 16% higher economic returns than Schemes I and III, respectively. The results also revealed that varying the selection proportion significantly influenced the annual selection response, index accuracy, and inbreeding rate. Increasing the flock size had little effect on the genetic progress but significantly reduced the inbreeding rate. Given its genetic and economic benefits alongside operational feasibility, Scheme II, with a 5% selection proportion and a flock size of 1200 breeding ewes, is appropriate for the genetic improvement of indigenous sheep in low-input systems.
设计并实施一个完善的育种计划对于可持续提高牲畜生产力至关重要。本研究评估了三种育种方案在低投入生产系统中对本地绵羊进行可持续遗传改良的效率。这些方案分别是在六个月龄（方案I）或周岁龄（方案II）进行单阶段选择，以及在六个月龄进行第一阶段选择、周岁龄进行第二阶段选择（方案III）。每个方案都用三个选择比例水平（5%、10%和20%）和四个群体规模（600、1200、1800和2400只繁殖母羊）进行评估。使用SelAction软件中采用的确定性方法模拟选择反应。对于六个月龄体重，年度预测遗传进展范围为0.177至0.267千克（方案I）和0.157至0.233千克（方案III）。对于周岁龄体重，模拟的年度遗传进展为0.268至0.399千克（方案II）和0.265至0.398千克（方案III）。每只繁殖母羊断奶羔羊数（NLW）和繁殖率的预期年度遗传进展通常较小，但方案II和方案III的估计值高于方案I。方案I、II和III估计的年度经济反应分别为0.393至0.591美元、0.589至0.879美元和0.494至0.744美元。值得注意的是，方案II的经济回报分别比方案I和方案III高34%和16%。结果还表明，改变选择比例会显著影响年度选择反应、指数准确性和近交率。增加群体规模对遗传进展影响不大，但会显著降低近交率。鉴于其遗传和经济效益以及操作可行性，选择比例为5%、群体规模为1200只繁殖母羊的方案II适用于低投入系统中本地绵羊的遗传改良。
