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Feed Efficiency in Swine

Improving feed conversion for more profitable pigs

Since feed cost represents up to 70% of the total cost in modern pork production, feed efficiency has an enormous effect on profitability of producers.  

Feed efficiency in swine is measured via feed consumed per unit of gain. This is typically calculated as a feed conversion ratio (FCR), which is measured as the feed intake over a period divided by the average daily gain (ADG). 

Feed efficiency is not only a key parameter of profitability, but also is an indication of the sustainable usage of grains and protein in livestock production. By taking actions that improve feed efficiency, such as optimizing gut health and enhancing nutrient digestibility, the industry decreases wastage and improves manure management.  

How to improve feed efficiency in pigs

Typically, when one 150 lb pig is fed on an ad libitum basis, approximately 34 % of daily energy intake is directed towards maintenance (Patience, 2012). In truth, this can vary greatly due to various factors. As a result, reducing maintenance costs and maximizing the amount of nutrient resources being directed towards weight gain can improve feed efficiency. Some of the factors that can affect feed efficiency are: 

  • Nutrient density
  • Feed form and quality
  • Health status
  • Environment
  • Feed additives

Nutrient density

Pigs utilize dietary nutrients for maintenance and protein and lipid accretion. The supply of energy, limiting amino acids, as well as vitamins and minerals should meet the requirement for each phase of production to ensure efficient growth.  

Feed form and quality

Particle size is strongly correlated with feed efficiency. It has been shown that reduction in the particle size of feed ingredients increases its surface area, thus improving digestibility; however, too fine of a grind can cause gastric ulcers (Cappai et al., 2013) and increase feed cost.  

Research has shown that feed efficiency improves by 1% to 1.2% for every 100 micron reduction in particle size (Healy et al., 1994). 

ItemParticle size, microns
Average daily gain, lb0.840.800.850.78
Average daily feed intake, lba1.
Feed efficiencyb1.551.521.461.53
Production rate, tons/hour4.062.841.630.85

 Adapted from Healy et al., 1994
aLinear effect (P < 0.08); bQuadratic (P < 0.01).

Health status

During the early stages of disease, pigs often have depressed feed intake, which results in poor growth. Nutrient absorption is compromised directly through injury to the intestinal epithelium. Other sources of inflammation, regardless of their duration, can cause gastrointestinal tract irritation which limits nutrient absorption for growth (McCracken et al., 1999). Reducing inflammation by limiting anti-nutritional factors such as mycotoxins or providing anti-inflammatory substances to the diet can alleviate reductions in nutrient absorption while also reducing subsequent intestinal disorders.  


To minimize the negative effects of potential environmental changes on growth, maintaining optimum temperatures, humidity, and airflow is critical. Poor sanitation can increase disease transmission and can impact feed efficiency. Furthermore, minimizing social stress can reduce unnecessary energy costs.  

Feed additives

The addition of functional feed additives is essential for optimal animal growth. Swine supplements commonly added to diets to achieve better feed efficiency include: 


Cappai M. G, M. Picciau, and W. Pinna. 2013. Ulcerogenic risk assessment of diets for pigs in relation to gastric lesion prevalence. BMC Vet Res. 9:36.

Healy, B. J., J. D. Hancock, G. A. Kennedy, P. J. Bramel-Cox, K. C. Behnke, and R. H. Hines. 1994. Optimum particle size of corn and hard and soft sorghum for nursery pigs. J. Anim. Sci. 72:2227.

McCracken, B. A., M. E. Spurlock, M. A. Roos, F. A. Zuckermann, and H. R. Gaskins. 1999. Biochemical and Molecular Action of Nutrients Weaning Anorexia May Contribute to Local Inflammation in the Piglet Small Intestine. J. Nutr. 129:613–619.

Patience, J. F. 2012. The Influence of Dietary Energy on Feed Efficiency in Grow-Finish Swine. In: Patience JF, editor. Feed Efficiency in Swine. Wageningen: Wageningen Academic Press. pp. 101–129.