Camerlink I, Bolhuis J E, Duijvesteijn N, van Arendonk J A M, Bijma P
Animal Breeding and Genomics Centre, Wageningen University, PO Box 338, 6700 AH Wageningen, The Netherlands Adaptation Physiology Group, Wageningen University, PO Box 338, 6700 AH Wageningen, The Netherlands
Adaptation Physiology Group, Wageningen University, PO Box 338, 6700 AH Wageningen, The Netherlands.
J Anim Sci. 2014 Jun;92(6):2612-9. doi: 10.2527/jas.2013-7220. Epub 2014 Mar 26.
Production traits such as growth rate may depend on the social interactions between group members. These social interactions may be partly heritable and are referred to as indirect genetic effects (IGE) or social, associative, or competitive genetic effects. Indirect genetic effects may contribute to heritable variation in traits and can therefore be used to increase the response to selection. This, however, has hardly been tested by selection experiments. Our objective was to determine the effects of 1 generation of selection on IGE for growth (IGEg) in pigs on ADG, BW, ADFI, feed efficiency, and postmortem measurements. Sires (n = 24) and dams (n = 64) were selected to create a high vs. low contrast for IGEg in the offspring (n = 480). The IGE difference was 2.8 g ADG per pen mate, corresponding to 14 g higher ADG in high IGEg offspring compared to low IGEg offspring when housed in groups of 6 (i.e., (6 - 1) × 2.8 = 14). Male (barrows) and female (gilts) offspring were housed in groups of 6 of the same IGEg classification, in either barren concrete pens or pens enriched with straw and wood shavings (n = 80 pens). Pigs were followed from birth to slaughter. Data were analyzed in a mixed model with pen as random factor. There was no difference in ADG between high and low IGEg pigs during the finishing period (wk 10 to 23). Opposite to expectations, high IGEg tended to have a 17 g lower ADG from weaning to slaughter (P = 0.08), which was caused by a higher BW of low IGEg pigs in wk 5 (P = 0.008). This led to a 2.3 kg lower carcass weight (P = 0.02) and 2.2 mm less muscle depth for high IGEg pigs (P = 0.03). High IGEg pigs had a higher stomach wall damage score (P = 0.01). Pigs on straw had a 25 g lower ADG during finishing (P = 0.03) and less stomach wall damage (P < 0.001). Fewer interventions against harmful behavior were required in high IGEg pigs. The unexpected results regarding IGEg may be due to several reasons. Despite initial power calculations showing good power, the IGEg contrast between groups may have been too small. Moreover, measures that were taken to limit harmful behavior may have had a substantial role. Harmful behavior such as tail biting may affect ADG and might underlie the effects of selection on IGEg in pigs. Research under commercial circumstances, where harmful behavior is likely to be more profound, may give more accurate insight into the benefits of selecting for IGEg.
生长速度等生产性状可能取决于群体成员之间的社会互动。这些社会互动可能部分具有遗传性，被称为间接遗传效应（IGE）或社会、关联或竞争遗传效应。间接遗传效应可能导致性状的遗传变异，因此可用于提高选择反应。然而，这几乎没有通过选择实验进行检验。我们的目标是确定一代选择对猪生长的间接遗传效应（IGEg）在平均日增重（ADG）、体重（BW）、平均日采食量（ADFI）、饲料效率和宰后测量方面的影响。选择了24头公猪和64头母猪，以使后代（480头）的IGEg形成高与低的对比。每头同栏伙伴的IGE差异为2.8克ADG，这意味着当6头一组饲养时，高IGEg后代的ADG比低IGEg后代高14克（即(6 - 1)×2.8 = 14）。雄性（阉猪）和雌性（后备母猪）后代按相同IGEg分类6头一组饲养，饲养在贫瘠的水泥栏或铺有稻草和木屑的栏中（共80个栏）。猪从出生一直跟踪到屠宰。数据在以栏为随机因素的混合模型中进行分析。育肥期（第10至23周）高IGEg和低IGEg猪的ADG没有差异。与预期相反，从断奶到屠宰，高IGEg猪的ADG往往低17克（P = 0.08），这是由于第5周时低IGEg猪体重较高所致（P = 0.008）。这导致高IGEg猪的胴体重低2.3千克（P = 0.02），肌肉深度少2.2毫米（P = 0.03）。高IGEg猪的胃壁损伤评分较高（P = 0.01）。饲养在铺有稻草栏中的猪在育肥期的ADG低25克（P = 0.03），胃壁损伤也较少（P < 0.001）。高IGEg猪需要针对有害行为的干预较少。关于IGEg的意外结果可能有几个原因。尽管最初的功效计算显示功效良好，但组间的IGEg对比可能太小。此外，为限制有害行为所采取的措施可能起到了重要作用。诸如咬尾等有害行为可能会影响ADG，并且可能是猪选择IGEg效应的潜在原因。在商业环境下进行的研究，那里有害行为可能更严重，可能会更准确地洞察选择IGEg的益处。
