West Central Research and Outreach Center, University of Minnesota, Morris 56267, USA.
J Anim Sci. 2012 Dec;90(12):4514-22. doi: 10.2527/jas.2011-4869. Epub 2012 Aug 2.
Young sows are subordinate and vulnerable in group-housing systems because they usually lose most fights and suffer more injuries than mature sows at mixing. This study was conducted to evaluate effects of sorting by parity on reducing aggression and associated stress with the aim to improve welfare and performance of first-parity sows in a group-housed system. Sows and gilts (n = 180) from 6 breeding groups were used. Within each group, 2 groups of 15 females were mixed in each of 2 treatment pens after weaning and remained there throughout the entire gestation period. The control pen consisted of 11 multiparous and 4 first-parity sows, and the treatment pen consisted of 11 gilts and 4 first-parity sows. Before mixing and at the end of the gestation period, sows and gilts were weighed individually, assessed for BCS, and measured for backfat thickness. Injury scores were assessed before and 48 h after mixing and wean-to-mating intervals, farrowing rate, and litter performance at the subsequent farrowing were recorded for all females. Aggressive interactions involving first-parity sows were video recorded for 72 h immediately after mixing in each pen. Data were analyzed using the Glimmix procedure of SAS with a Poisson regression model for count data and a Gaussian model for continuous data. All females in treatment pens sustained fewer scratches (P = 0.01) after mixing than females in control pens. First-parity sows in treatment pens fought more frequently (P = 0.01), tended to fight for longer periods (P = 0.08), and won more fights (P = 0.04) of parallel pressing but had fewer injures (P = 0.03) after mixing, gained more BW (P = 0.01) during gestation, and had greater farrowing rates (P = 0.03) compared with first-parity sows in control pens. The results suggest that sorting by parity shielded first-parity sows from severe injuries caused by mixing-induced aggression so that their welfare and performance can be improved in group housing systems.
青年母猪在群体饲养系统中处于从属和脆弱的地位，因为它们在混合时通常会输掉大多数战斗，并且比成年母猪遭受更多的伤害。这项研究旨在评估通过胎次分类来减少攻击性和相关应激的影响，目的是提高群体饲养系统中初产母猪的福利和性能。使用了来自 6 个繁殖组的 180 头母猪和后备母猪。在每个组内，断奶后将两组各 15 头母猪混合在两个处理栏中，整个妊娠期都留在那里。对照栏包括 11 头经产母猪和 4 头初产母猪，处理栏包括 11 头后备母猪和 4 头初产母猪。在混合前和妊娠期结束时，对母猪和后备母猪进行个体称重，评估体况评分（BCS），测量背膘厚度。在混合前后和断奶至配种间隔、产仔率以及随后的产仔性能方面记录所有母猪的受伤评分。在每个栏中混合后立即对涉及初产母猪的攻击性互动进行视频记录 72 小时。使用 SAS 的 Glimmix 程序分析数据，使用泊松回归模型分析计数数据，使用高斯模型分析连续数据。与对照组相比，处理栏中的所有母猪在混合后遭受的划痕更少（P = 0.01）。处理栏中的初产母猪更频繁地打架（P = 0.01），打架时间更长（P = 0.08），在平行按压中赢得更多的战斗（P = 0.04），但受伤更少（P = 0.03），混合后妊娠期内体重增加更多（P = 0.01），产仔率更高（P = 0.03）与对照组中的初产母猪相比。结果表明，通过胎次分类可以使初产母猪免受混合诱导的攻击性造成的严重伤害，从而提高其在群体饲养系统中的福利和性能。
