Social rank of pregnant sows affects their body weight gain and behavior and performance of the offspring1,2

Abstract

Previous studies on group housing of pregnant sows have mainly focused on reproduction, but we hypothesized that the social rank of pregnant sows housed in groups could also affect birth weight, growth, and behavior of their offspring. Therefore, in the present study, pregnant gilts and sows were housed in 15 different groups (n = 7 to 14 animals per group) from 4 d after AI until 1 wk before the expected farrowing date. All groups were fed by an electronically controlled sow feeding system that registered, on a 24-h basis, the time of first visit, number of feeding and non-feeding visits, and number of times succeeding another sow within 2 s. Only in the first 6 groups (n = 57 animals), agonistic interactions were observed continuously. The percentage of agonistic interactions won was highly correlated (r(s) = 0.90, P < 0.001) with the percentage of displacement success (DS) at the feeding station, which was calculated as: [the number of times succeeding another sow within 2 s/(the number of times succeeded by another sow within 2 s + the number of times succeeding another sow within 2 s)] x 100. This allowed us to classify all sows (n = 166) according to their DS: high-social ranking (HSR) sows had a DS >50% (n = 62) and low-social ranking (LSR) sows a DS <50% (n = 104). Body weights before AI did not differ between HSR and LSR sows, but HSR sows gained more BW during gestation, and lost more BW and back-fat during lactation (P < 0.001). Maternal salivary cortisol concentrations at 2, 7, and 13 wk after AI did not differ between HSR and LSR sows, nor did gestation length, litter size, or percentage of live born piglets. During a novel object (NO) test at 3 wk of age, HSR offspring moved and vocalized more than LSR offspring (P < 0.05). In addition, the latency time to touch the NO was shorter in HSR offspring (P < 0.05), and HSR males spent more time near the NO than LSR males (P < 0.01). At weaning, HSR offspring weighed more than LSR offspring (P < 0.05), and at slaughter HSR offspring had more lean meat than LSR offspring (P < 0.05). Results indicate that the social rank of the sow during gestation affects her own BW gain and loss as well as the growth and behavior of her offspring. Pig breeders that apply group housing for pregnant sows should pay attention to reducing competition around the feeding area, which may reduce aggression among the sows and minimize differences between HSR and LSR sows.

Individual variation in sow aggressive behavior and its relationship with sow welfare1

“…On the other hand, subdominant animals may risk receiving aggression to access feed or improve their social order or both, but the associated energy expenditure and stress from consistently engaging in aggression could result in reduced weight gain. Interestingly, both Mendl et al (1992) and Kranendonk et al (2007) found sows of high social rank to gain the most weight during gestation, even though animals were fed using an electronic sow feeder. Mendl et al (1992) suggested that increased fear and anxiety of attack could increase basal metabolic rates and, thus, expenditure of energy of middle-ranking sows, compromising growth.…”

Heritability of shoulder ulcers and genetic correlations with mean piglet weight and sow body condition

“…Older sows have also been exposed to environmental risk factors for a longer time than sows in early parities (Kaiser et al, 2007). On the other hand, when sows are group fed, older sows usually maintain a better body condition due to a higher rank in the group (Brouns and Edwards, 1994;Kranendonk et al, 2007;Hoy et al, 2009). Health status and stress response are other factors that could influence the presence of shoulder ulcers (Bonde et al, 2007).…”

Ganho de peso de porcas gestantes associado ao comportamento em baias e à uniformidade da leitegada

“…A associação entre ganho de peso, no final da gestação, e comportamento das fêmeas, durante a alimentação, também é reforçada pela maior presença, no cocho, de fêmeas do subgrupo alto ganho de peso, em comparação àquelas com baixo e médio ganho de peso. Kranendonk et al (2007) …”

“…A maioria dos trabalhos de pesquisa são relacionados ao tipo de alojamento no terço inicial (Kranendonk et al, 2007;Remience et al, 2008) ou médio da gestação (Séguin et al, 2006;Jansen et al, 2007), e poucos estão relacionados a fêmeas mantidas em alojamento coletivo no terço final da gestação, com avaliação de ganho de peso e desempenho produtivo.…”