The course of parturition in two sow genotypes and two hut designs under free-range conditions

Investigating the effects of two weaning methods and two genetic hybrids on play behavior in weaner pigs (Sus scrofa)

In conventional pig production, suckling pigs are typically weaned between 3 and 5 weeks of age. This involves separation from the sow, dietary change, and regrouping in a novel environment, which challenge the welfare of pigs. We investigated the effects of two weaning methods [conventional weaning: two litters mixed in a weaner pen of different size and design (MOVE) vs. litter staying in the farrowing pen after removing the sow (STAY)] and two genetic hybrids [DanBred Yorkshire × Landrace (approximately 21 total pigs born/litter; DB) vs. Topigs Norsvin TN70 Yorkshire × Landrace (approximately 16 total pigs born/litter with higher individual birth weight and weaning weight than DB; TN)] on play behavior across weaning. Both genetic hybrids were inseminated with semen of DanBred Duroc boars. Litters were reduced to the number of functional teats at birth. The durations of locomotor-rotational play (LOC) and social play (SOC) of 24 indoor-housed litters [pigs/litter: (average ± SD) 13 ± 2; age at the weaning day: 26 ± 2 days] were video-recorded continuously between 14:00 h and 22:00 h on days −1, 1, and 2 relative to weaning and statistically analyzed with mixed-effects modeling at the individual level. Before weaning, TN pigs performed LOC longer than DB pigs. On day 2 post-weaning, STAY pigs engaged in more SOC than MOVE pigs. Moreover, TN pigs and STAY pigs displayed a steeper increase in LOC from days 1 to 2 than DB pigs and MOVE pigs, respectively. We demonstrated that pigs belonging to the genetic hybrid with higher weight at birth and weaning spent more time playing on the day before weaning. Additionally, weaning pigs in the farrowing pen and, hence, avoiding social mixing and relocation to an unfamiliar environment had a positive effect on social play after weaning. Our study illustrates that weaning stress in pigs may be reduced by using a genetic hybrid featuring higher birth and weaning weight and by keeping litters intact in a familiar environment after weaning. This study also supports the use of play behavior as an animal welfare indicator.

Characteristics of Piglets Born by Two Highly Prolific Sow Hybrids

High piglet mortality constitutes a welfare challenge in Danish organic pig production with almost one in three piglets dying before weaning. Piglet characteristics such as birth weight, rectal temperature and intrauterine growth restriction (IUGR) affect piglet survival. Due to differences in breeding goals, these characteristics may be expected to differ between sow hybrids. Thus, the aims of the present study were (1) to investigate piglet characteristics in two highly prolific sow hybrids and (2) to study to which extent the aforementioned characteristics affect piglet mortality. Forty-nine sows (22 DanBred and 27 Topigs Norsvin) were followed in their first two parities. Sows were housed outdoors and gave birth in huts. On day 1 postpartum ( pp ) piglets were individually marked, weighed, their rectal temperature was recorded and they were scored for IUGR. Weight and rectal temperature were recorded again 3 days pp. Principal component analyses were conducted to explore relationships among variables. Early piglet death grouped with IUGR, lower rectal temperature and weight on day 1 pp. Late mortality grouped with increasing litter size and DanBred hybrid. Whilst, Topigs Norsvin hybrid grouped with increasing rectal temperature day 3 pp, longer crown to rump length, higher weight and more teats on the sow. Results of the statistical analyses showed that Topigs Norsvin piglets were heavier 1 and 3 days pp (p < 0.001) compared to DanBred piglets. Furthermore, Topigs Norsvin piglets had a higher rectal temperature than DanBred on day 1 pp (p = 0.023). The risk of IUGR depended on an interaction between sow hybrid and parity (p = 0.023). DanBred sows gave birth to more piglets (18.2 ± 0.6) than Topigs Norsvin sows (15.7 ± 0.5, p = 0.003), however, DanBred sows had fewer teats than Topigs Norsvin sows. Weight on day 1 pp affected both the odds of stillbirth (p < 0.001) and live born death (p < 0.001). Lower rectal temperature day 1 pp (p < 0.001) increased the odds of live born death. In conclusion, the investigated hybrids differed in several piglet characteristics related to piglet mortality. Use of sows giving birth to heavier and fewer piglets in the litter may thus be a useful tool to reduce piglet mortality in pig production with outdoor farrowing.