Rajab M H, Blackburn H D, Cartwright T C, Figueiredo E A
Stat. Dept. Texas A&M University, College Station 77843.
J Anim Sci. 1991 Nov;69(11):4397-405. doi: 10.2527/1991.69114397x.
The Texas A&M Sheep Simulation Model was used to examine genetic-environmental interactions (GEI) among Brazilian Somali, Morada Nova, and Santa Ines breeds and type and level of feed supplement in northeast Brazil. Two sets of simulations were conducted to examine effects of different supplement quality (napier grass vs cunha legume) and quantity (napier grass only). The analyses indicated the benefits from supplementing lambs at weaning during the dry season and from supplementing lactating ewes at the beginning of lambing season when forage is scarce. The cunha legume was an effective supplement, but choosing between cunha legume and napier grass is an economic consideration. Increasing the amount of napier grass supplement per ewe from 200 g/d to 400 g/d resulted in a significant GEI (i.e., different levels of response such as lamb mortality rate, lamb weaning weight, and lambing rate for different breeds). The Brazilian Somali was the least responsive, whereas the Santa Ines was the most responsive to supplementation. It was concluded that the level of supplement should be higher for the Santa Ines and Morada Nova than for the Somali. The amount of supplement should be regulated so that it neither substitutes for nor lowers the utilization of the native caatinga forage. None of the breeds was simulated to be superior in all environments. Thus, considering the wide range of resources of individual farmers, any one of these breeds may be the preferred choice, depending on the individual set of production resources.
德克萨斯农工大学绵羊模拟模型被用于研究巴西索马里、莫拉达诺瓦和圣伊内斯品种之间的基因 - 环境相互作用（GEI），以及巴西东北部饲料补充剂的类型和水平。进行了两组模拟，以研究不同补充剂质量（象草与库尼亚豆科植物）和数量（仅象草）的影响。分析表明，在旱季断奶时给羔羊补充饲料，以及在产羔季节开始时牧草稀缺时给泌乳母羊补充饲料是有益的。库尼亚豆科植物是一种有效的补充剂，但在库尼亚豆科植物和象草之间进行选择是一个经济考量。每只母羊的象草补充量从200克/天增加到400克/天会导致显著的基因 - 环境相互作用（即不同品种在羔羊死亡率、羔羊断奶体重和产羔率等方面有不同的反应水平）。巴西索马里品种反应最小，而圣伊内斯品种对补充饲料反应最大。得出的结论是，圣伊内斯和莫拉达诺瓦品种的补充水平应高于索马里品种。应调节补充量，使其既不替代也不降低当地卡廷加牧草的利用率。没有一个品种在所有环境中都表现出优势。因此，考虑到个体农户资源的广泛差异，根据个体生产资源的不同，这些品种中的任何一个都可能是首选。
