The animal article of the month for September is ‘Review: Divergent selection for residual feed intake in the growing pig‘.

Improving feed use in livestock remains a challenge in most animal species. Despite significant improvements in animal genetics and management, feed cost still represents about two thirds of the production cost in Western countries (69% in pigs in 2013 in France). In addition to the economic pressures of feeding livestock, reducing the environmental impact and the competition with land use for the production of human food and biofuel are all major challenges.

The substantial progress made since the 1960s to increase the growth rate of animals and to improve feed efficiency in pigs has resulted in unfavourable effects on meat quality.

With this in mind, the authors of this paper – published in the journal Animal – looked at the challenges for improving feed efficiency in growing pigs over ten generations. Drawing on results gathered by the French Institut National de la Recherche Agronomique (INRA) from pigs in France and the US, this group of French scientists studied the long-term impacts on growing pigs raised under standard conditions and in alternative conditions – such as heat stress, inflammatory challenges or lactation.

What they found was that selection for low residual feed intake in growing pigs was feasible with limited impacts on other production traits. There were some changes in meat quality, in relation to modified muscular energy metabolism. However, selection on residual feed intake did not affect the digestibility of nutrients and energy. This suggests that a genetic improvement of digestibility can only be achieved if measures are recorded on pigs that are fed diets containing dietary fibres.

One major finding of the study was that there was no marked reduction of the pigs’ ability to face challenges, including lactation during reproduction. Residual feed intake can therefore be used to improve feed efficiency in growing pigs. However, understanding the relationships between residual feed intake and responses to stress and energy and amino acid demanding processes, as such immunity and lactation, remains a significant challenge. Indicators to identify efficient sows with high lifetime feed efficiency and longevity were pointed out as a side result of the studies on reproductive females.

The French-led study concluded that feed efficiency remains a trait that is expensive to calculate due to the cost of measuring individual feed intake in group-housed animals. However, no convincing genomic or bio-marker was identified, so methodologies using direct phenotyping and genomic selection are likely to be the key to breeding programmes to guarantee feed efficiency in future.

This article is freely available for one month: ‘Review: Divergent selection for residual feed intake in the growing pig‘.

Author: Hélène Gilbert

The animal Article of the Month is selected by the Editor-in-Chief and is freely available for one month. View the recent selections

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