Addition of arginine and leucine to low or normal protein diets: performance, carcass characteristics and intramuscular fat of finishing pigs

Núria Tous,Enric Esteve-Garcia,Marina Gispert,Maria Font-I-Furnols,Rosil Lizardo,Borja Vilà

doi:10.5424/sjar/2016144-9351

Abstract

The effect of dietary crude protein (CP) reduction, supplementation with arginine or leucine on intramuscular fat (IMF) content was evaluated in (Landrace × Duroc) × Pietrain pigs. One-hundred and eight barrows (67 ± 4 kg) were assigned to six diets (n=6 pens of 3 pigs each): four normal CP diets containing 16% CP from 60 to 90 kg and 13% CP from 90 to 115 kg live weight (normal protein; normal protein high Arg, normal protein high Leu or normal protein high Arg and Leu) and two low CP diets containing 14% CP from 60 to 90 kg and 11.8% CP from 90 to 115 kg live weight (with or without supplementation of both amino acids). The high Leu and Arg diets were supplemented to obtain ratios of standard ileal digestible Leu/Lys and Arg/Lys of 4 and 2, respectively. While feed to gain ratio tended to increase (p<0.05), final weight (p<0.01), average daily feed intake (ADFI) (p<0.05) and average daily gain (ADG) (p<0.01) were reduced in animals fed low-protein diets supplemented with Arg and Leu compared to the ones fed low-protein diet unsupplemented. Marbling and IMF content in loin were reduced when Arg was supplemented (p<0.05) in normal protein diets. Supplementing these diets with Arg also reduced belly weight (p<0.01) and increased lean meat percentage (p<0.05). Contrary to the initial hypothesis, reduction of CP or dietary supplementation with Leu had no effect on IMF content and supplementation with Arg reduced it.

Highlights

One of the characteristics that influence the quality of meat as perceived by the consumer is the amount of intramuscular fat (IMF), which is located within the structure of muscle
Animals fed normal protein diets supplemented with Arg or Leu tended to have a greater final weight and average daily gain (ADG) compared to animals fed normal protein diet or normal protein diet supplemented with both amino acids Arg and Leu
When both Arg and Leu were added in excess in normal protein diet final body weight and ADG were similar to normal protein diet without amino acid supplementation

Summary

Introduction

One of the characteristics that influence the quality of meat as perceived by the consumer is the amount of intramuscular fat (IMF), which is located within the structure of muscle. IMF is well correlated with pork acceptability. The threshold level of IMF needed for optimal eating quality of pork proposed is between 2.2 and 3.4% (Font-i-Furnols et al, 2012). The trend in pig production has been to increase the carcass lean content, reduce carcass fat, and the end result is that IMF content has decreased. IMF can be as low as 1% (Channon et al, 2001). One of the challenges for nutritionists is to increase the level of IMF without increasing backfat or impairing the animal growth

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