QFTJMTHG

3207

21 décembre 2020 16:18

12 avril 2021 15:15

High piglet mortality is a considerable problem in Danish organic pig production where it has been estimated that approximately one third of all piglets die before seven weeks of age. The high preweaning mortality has a great negative impact on both piglet welfare and herd economy. Concerns about animal welfare is a key motivator for consumers to purchase organic products and consumers particularly value ‘animal welfare’ and display a positive attitude towards paying for this issue. The majority of the deaths occurs within the first week post-partum (pp) with stillbirth, crushing and starvation being the most common causes. Little is known about potential risk factors for preweaning mortality in the Danish organic pig production and thus, further research is an essential prerequisite for lowering the preweaning mortality. Therefore, the overall objective of this thesis was to determine causes of preweaning mortality and to identify risk factors for stillbirth and early piglet mortality within the Danish organic pig production. An observational study was performed in nine Danish organic sow herds over a 1-year period from June 2014 to May 2015. The herd size ranged from 80 to 910 productive sows per year. All farrowings within the nine herds throughout the study period were included in the study. The data collection comprised of two parts: (1) A detailed recording of dead /alive piglets together with information about the sows in the farrowing field and (2) Postmortem (pm) examinations on a subsample of dead piglets collected from selected sows. Collection of piglets was done once in each season throughout the 1-year study period. The stock personnel working in the herds performed the recordings of mortality in the farrowing field and collected dead piglets for pm examinations. Piglets were kept frozen at the farm and thawed prior to pm examinations, which were conducted by a trained pathologist. The results of the study are described in three scientific papers included in this thesis. The objective of paper I was to identify sow-level risk factors for stillbirth in organic Danish sow herds. Data was analysed using regression analysis to evaluate parity, sow body condition, season, and total born litter size as risk factors for stillbirth. The results showed a significant interaction between sow body condition and parity. In primiparous sows, an increase in body condition from thin to normal and from normal to fat increased the probability of stillbirth. In sows with more than four parities, an increase in sow body condition from thin to normal and from normal to fat lowered the probability of stillbirth. Additionally, a significant effect of season was found, with an increased probability of stillbirth during summer (May to August) compared with the remaining part of the year. Lastly, a non-linear effect of litter size was confirmed, where an increase of total born litter size resulted in an increased probability of stillbirth. The objective in paper II was to identify sow-level risk factors for early mortality and crushing in organic Danish sow herds. A negative binomial regression analysis was performed to evaluate parity, sow body condition, season, live-born litter size, and stillborn littermates as risk factors for mortality from parturition until castration (3 - 5 days pp). A regression analysis was performed to evaluate parity, sow body condition, season, liveborn litter size, and stillborn littermates as risk factors for crushing from parturition until castration (3 - 5 days pp). The results showed that one or more stillborn littermates, being born during the summer, high parity, and sow body condition significantly increased the risk of mortality from parturition until castration. Moreover, the study found that the risk of being crushed increased significantly with increasing litter size and parity of the sow.The objective of paper III was to determine the cause of death by necropsy on a subsample of dead piglets and to evaluate the effect of sow parity and season on the proportions of the identified causes of mortality. In total, 2672 piglets were necropsied. It was found that the majority of the live-born necropsied piglets died of crushing (77 %) and starvation (10 %). Moreover, 81 % of live-born necropsied piglets died within 4 days pp and half of these piglets had a body weight of less than 1 kg at the time of death. Crushed piglets dying within four days pp were a heterogeneous group consisting of both heavy piglets with full stomachs and piglets with a low body weight and empty stomachs. The proportion of crushed piglets were affected by parity and season, where fewer piglets were crushed during summer compared to the remaining part of the year, and more piglets were crushed by multiparous sows compared to first parity sows. Moreover, the proportion of prepartum stillbirths was higher in autumn compared to the remaining part of the year and in multiparous sows compared to first parity sows. Finally, it was shown that the average total preweaning mortality was to 29.5 % (ranging from 21.4% to 39.9 %between herds) within the study population. Based on the results presented in this thesis, it is concluded that increasing litter size, high parity, sow body condition, and being born during summer are all risk factors for preweaning mortality within the Danish organic pig production. The large variation in total preweaning mortality between the herds indicates that it is possible to achieve a lower piglet mortality in the future and that the Danish organic pig production and a high piglet mortality is not inevitably synonymous.

None

• AB - Spécifique
• FREDO mode élevage, bien-être et qualité
• GEO Danemark
• porc
• porcelet
• élevage

2017

1 janvier 2017