Animal Production Science Animal Production Science Society
Food, fibre and pharmaceuticals from animals
RESEARCH ARTICLE

The sex ratio of a gilt’s birth litter can affect her fitness as a breeding female

J. Seyfang A D , R. N. Kirkwood A , A. J. Tilbrook B C and C. R. Ralph B
+ Author Affiliations
- Author Affiliations

A Animal Welfare Science Centre, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, SA 5371, Australia.

B Animal Welfare Science Centre, South Australian Research and Development Institute, Primary Industry and Regions SA, J.S. Davies Building, The University of Adelaide Campus, Roseworthy, SA 5371, Australia.

C Present address: Centre for Animal Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, Qld 4072, Australia.

D Corresponding author. Email: jemma.seyfang@adelaide.edu.au

Animal Production Science - https://doi.org/10.1071/AN17192
Submitted: 31 March 2017  Accepted: 10 October 2017   Published online: 11 January 2018

Abstract

Lifetime reproductive performance and behaviour are established in utero driven by genetics and the steroidal milieu of the uterine environment. Developing males synthesise androgens that can be absorbed by females in the litter. Consequently, the proportion of males in a litter has the potential to affect both lifetime reproductive performance and behaviour of female littermates. Although reproductive potential is understandably important for gilt selection, behaviour is becoming progressively more important as group housing of sows increases. Aggression can be a cause for removal from the breeding herd, and can also negatively affect reproductive performance and herd longevity. This review covers existing evidence of masculinisation in rodents and sheep, the mechanism causing masculinisation, and the knowledge gaps surrounding masculinisation in pigs. Premature culling of gilts is an economic and animal welfare issue in the pork industry resulting in low retention of gilts and reduced productivity. The selection of gilts needs to be improved to incorporate both lifetime reproductive potential and behaviour. We determined that there is cause to investigate the effect of the birth litter sex ratio of a gilt on her suitability for selection into the breeding herd.

Additional keywords: behaviour, fetal development, reproduction.


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