Rault J-L, Morrison R S, Hansen C F, Hansen L U, Hemsworth P H
Animal Welfare Science Centre, University of Melbourne, Parkville VIC 3010, Australia
Rivalea Australia, Corowa NSW 2646, Australia.
J Anim Sci. 2014 Dec;92(12):5683-92. doi: 10.2527/jas.2014-8238. Epub 2014 Nov 17.
This project compared the effects of grouping sows after weaning or within 2 d after insemination on sexual behavior, aggression, injuries, stress, and mating success. At weaning (d 0), 360 sows were housed in groups of 10 sows at 4.4 m2 per sow (group weaned [GpW]) or individual stalls (stall weaned [StW]), with 18 groups per treatment. Six days after weaning (d 6), 7 inseminated GpW sows were moved to pens at 2.1 m2 per sow and keeping acquainted sows, and simultaneously, groups of 7 inseminated StW sows were mixed at 2.1 m2 per sow. Group-weaned sows showed greater variation in the onset of estrus (P=0.02) but not in the length of estrus compared to StW sows (P=0.21), with 7% fewer GpW sows inseminated within 5 d of weaning (P=0.05). Group-weaned sows showed lower sexual receptivity scores, showing less spontaneous standing during boar exposure and partly compensating by a greater response to the back-pressure test (both P<0.01). The GpW treatment also showed greater variability in sows inseminated twice within 6 d of weaning, with 3 out of 18 pens having only 5 mated sows out of 10. Mixing after weaning resulted in higher levels of stress than mixing after insemination, with GpW sows having higher plasma cortisol concentration than StW sows on d 1 (P<0.001) but no treatment differences on d 7 in cortisol concentration or aggression at feeding (P=0.48). Group-weaned sows experienced greater weight loss during the first week postweaning (P=0.05). Anogenital sniffing in GpW sows was frequently observed from d 2 to 5, but mounting and flank nosing increased on d 4 and 5. Frequency of sexual behavior initiated by GpW sows tended to correlate with weight loss (P=0.08), and sexual behavior received correlated positively with cortisol concentration at d 1 (P=0.005). In conclusion, sows housed in groups at weaning and regrouped after insemination experienced higher stress than sows housed in individual stalls at weaning and mixed in groups after insemination. This resulted in lower mating success within 5 d of weaning, which in turn increased between-week variability. The lower sexual receptivity in sows grouped at weaning may be due to suppressed estrus-related behaviour, with ovulation occurring, or delayed ovulation beyond d 6. Further research is needed to identify underlying mechanisms to reduce variability, manage aggression and sexual behavior, and optimize estrus detection in group-housed weaning systems.
本项目比较了断奶后或授精后2天内对母猪进行分组对其性行为、攻击性、损伤、应激及配种成功率的影响。在断奶日（第0天），360头母猪按每头母猪4.4平方米的空间，以每组10头的方式饲养（断奶后分组饲养[GpW]）或饲养在个体栏位中（断奶后单栏饲养[StW]），每种处理18组。断奶后6天（第6天），7头授精后的GpW母猪被转移到每头母猪2.1平方米的栏舍中，并与熟悉的母猪一起饲养，同时，将7头授精后的StW母猪按每头母猪2.1平方米的空间进行混群。与StW母猪相比，GpW母猪发情开始的时间差异更大（P=0.02），但发情持续时间无差异（P=0.21），断奶后5天内接受授精的GpW母猪少7%（P=0.05）。GpW母猪的性接受评分较低，在公猪接触期间自发站立较少，部分通过对背压试验的更大反应进行补偿（两者P<0.01）。GpW处理在断奶后6天内接受两次授精的母猪中也表现出更大的变异性，18个栏中有3个栏的10头母猪中只有5头交配。断奶后混群比授精后混群导致更高的应激水平，第1天GpW母猪的血浆皮质醇浓度高于StW母猪（P<0.001），但第7天皮质醇浓度或采食时的攻击性无处理差异（P=0.48）。GpW母猪在断奶后的第一周体重减轻更多（P=0.05）。从第2天到第5天经常观察到GpW母猪的肛门生殖器嗅闻行为，但在第4天和第5天爬跨和侧嗅行为增加。GpW母猪发起性行为的频率与体重减轻呈正相关（P=0.08），接受性行为与第1天的皮质醇浓度呈正相关（P=0.005）。总之，断奶时群居并在授精后重新分组的母猪比断奶时饲养在个体栏位中并在授精后混群的母猪经历更高的应激。这导致断奶后5天内配种成功率较低，进而增加了周间变异性。断奶时群居的母猪性接受性较低可能是由于发情相关行为受到抑制，排卵已经发生，或者排卵延迟到第6天以后。需要进一步研究以确定潜在机制，以减少变异性、管理攻击性和性行为，并优化群居断奶系统中的发情检测。
