国家肉羊产业技术体系 - 不同时期交配并用紫花苜蓿放牧的母羊的繁殖性能

不同时期交配并用紫花苜蓿放牧的母羊的繁殖性能

编辑：贺善云 2015-10-14

目前研究发现在妊娠早期紫花苜蓿摄入量高的的牧场或其他高质量饮食的喂养可能增加胚胎死亡率，而提高营养对排卵率没有任何效果。研究人员为了确定前7天放牧紫花苜蓿（Medicago sativa）的牧场的绵羊和整个过程都加入比在连续加入七天之后不再加或母羊放牧的牧场整个阶段处于衰老期是否会导致更大的胎儿数量，故将美利奴母羊（300）分配成三个处理两个重复，放牧草场在7天和36天之间不同步的在秋天加入。

研究结果发现，放牧苜蓿加入7天导致每头母羊比衰老的牧场放牧（分别1.60±0.07和1.31±0.07）和多于19%只羔羊标记的每头配种母羊多30%（P＜0.05）胎数。延长过去7天放牧苜蓿的加入与放牧苜蓿只加入7天的相比，没有导致每只母羊额外的胎数（1.61±0.06）。从研究结果可以看出，加入前14天过程中大于80%的母羊交配，各处理组之间返情母羊和重新交配（0.18±0.022）以及没有妊娠（0.09±0.017）母羊的比例相似（P＞0.05），表明测定胚胎死亡率的处理组间没有显着差异。虽然之前加入的7天的放牧可能不会获得额外的效益，但对在添加苜蓿之前自然循环放牧的母羊和在秋天加入苜蓿期间的母羊可用来提高羔羊出生的数量。

原文摘要如下：

Reproductive performance of ewes grazing lucerne during different periods around mating

Robertson SM¹, Clayton EH², Friend MA³

Abstract: High intake of lucerne pastures or feeding of other high quality diets during early pregnancy may increase embryo mortality, negating any benefit of improved nutrition on ovulation rate in ewes. This study was conducted to determine whether grazing ewes on lucerne (Medicago sativa) pastures for 7 days prior to and throughout joining would result in greater foetal numbers than if ewes were removed 7 days after the commencement of joining, or if ewes grazed senescent pasture throughout the joining period. Merino ewes (300) were allocated to two replicates of three treatments, grazing pastures between Days-7 and 36 of an unsynchronised, natural autumn joining. Grazing lucerne to Day 7 of joining resulted in 30% more (P<0.05) foetuses per ewe than grazing senescent pasture (1.60±0.07 and 1.31±0.07, respectively), and 19% more lambs marked per ewe joined. Extending grazing of lucerne past Day 7 of joining did not result in additional foetuses per ewe (1.61±0.06) in comparison with only grazing lucerne to Day 7 of joining. Greater than 80% of ewes mated during the first 14 days of joining, and the proportions of ewes returning to oestrus and re-mating (0.18±0.022) and of non-pregnant (0.09±0.017) ewes were similar (P>0.05) among all treatment groups, suggesting no differences between treatments in embryo mortality. Grazing naturally cycling ewes on lucerne prior to and during joinings in autumn is recommended as a means to increase the number of lambs born, although additional gains may not be obtained by grazing past day seven of joining.

Keywords: Embryo mortality, Flushing, Nutrition, Reproduction, Sheep, Wool

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