Sow level risk factors for early piglet mortality and crushing in organic outdoor production

Abstract

Piglet mortality is a major problem in organic pig production affecting both farm economy and animal welfare. Knowledge is scarce on the risk factors of piglet mortality in Danish commercial organic pig production. The objectives of this study were to evaluate season, litter size, parity, sow body condition and stillborn littermates as risk factors for early piglet mortality and crushing of liveborn piglets from parturition until castration at day 3 to 5 postpartum (pp). The study was conducted over a 1-year period in nine commercial Danish organic pig herds practicing outdoor farrowing all year round. Data included recordings on 3393 farrowings with 50 284 liveborn piglets of which 14.8% died before castration. A subset of the dead piglets were collected and necropsied to identify crushed piglets. The average number of liveborn piglets per litter was 14.8 (SD=3.7) and the average time from parturition until castration was 4.1 (SD=1.7) days. A negative binomial regression analysis was used to model the effect of the predictive variables on the early piglet mortality accounting for different time periods from parturition to castration. An increase in maternal body condition score (BCS) and parity significantly increased the risk of dying between parturition and castration. Early mortality was found to be lowest during spring (March to May) and highest during summer (June to August). Being born into a litter with one or more stillborn littermates increased the risk of early mortality. The risk factors for crushing of piglets were evaluated using a logistic analysis. A significant effect of parity and litter size was found where the odds of at least one piglet in a litter with mortality was diagnosed as crushed increased with increasing parity and litter size. In conclusion, being born during summer (June to August), high parity and maternal BCS and stillborn littermates were found to be risk factors for piglet mortality between parturition and castration. In addition, parity and increasing litter size were found to be risk factors for crushing of piglets in litters with mortality.

Animal Welfare and Production Challenges Associated with Pasture Pig Systems: A Review

“…Conversely, piglets profit from greater temperature and temperature-humidity indexes after farrowing, with a significant decrease in pre-weaning mortality [12]. Furthermore, season and environmental temperature have shown to influence piglet mortality [41]. For instance, increased numbers of stillborn have been reported during periods of high temperature (≥27 • C) [42].…”

“…The impossibility of behaving naturally due to confinement, and the privation of environmental stimulation have been identified among the main causes of boredom and frustration in indoor managed pigs [24,39]. Additional potential consequences to lack of exercise are more health related: impairment of the cardiovascular system, and weakness of bones and muscles which frequently cause lameness [41]. However, free-range pigs have been reported to have more frequent and severe osteochondrosis than indoor pigs; nevertheless, these pigs did not show lameness [109].…”

“…Nursing piglet mortality was lower in combined outdoor-indoor and outdoor systems when compared to indoor systems [110]. In outdoor systems, piglet mortality has been associated with factors related to the environment [41,44,224]. Most deaths are the consequence of sows crushing piglets (causing injuries and even death), hypothermia, and starvation, and often happen during the first week of life [43,49,127].…”

“…The main cause of piglet (0-4 day old) death in organic herds in Denmark was sow crushing and starvation specially in multiparity sows [44]. Higher mortality was observed in larger litters, and was related to long farrowing, weight heterogeneity, presence of stillborn [23,41], decreased colostrum and milk intake, and behavior of piglets (by staying close to their mothers) [23]. The likelihood of piglet survival has been linked to piglet weight and body shape, and their ability to suckle colostrum [12,43].…”

Labelling as a Tool for Improving Animal Welfare—The Pig Case

“…Further, tail docking and castration are painful mutilations, decreasing piglet welfare [11]. Free farrowing systems [20] and outdoor farrowing in huts for highly prolific sows [21] may increase piglet mortality compared to crated sows.…”