Increasing carcass lean content while reducing carcass fat has been the trend in pig production for the last decades. As a result, intramuscular fat (IMF), which has been correlated with pork quality and acceptability, has decreased. According to some researchers, supplementing pig diets with leucine (Leu) or arginine (Arg) could increase IMF. The objective of the present study was to assess the effect of dietary crude protein (CP) reduction, supplemented with arginine or leucine on intramuscular fat (IMF) content in (Landrace × Duroc) × Pietrain pigs. For this purpose, a total of one-hundred and eight barrows (67 ± 4 kg) were allotted to six dietary treatments (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 and supplemented with normal protein (1); normal protein with high Arg content (2), normal protein with high Leu content (3) or normal protein with high Arg and Leu contents (4) 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 (5) and without (6) supplementation of both amino acids. High leucine and arginine diets were supplemented to obtain ratios of standard ileal digestible Leu/Lys and Arg/Lys of 4 and 2, respectively.
Final body weight, average daily feed intake (ADFI) and average daily gain (ADG) were reduced while feed to gain ratio tended to increase in animals fed low-protein diets supplemented with Arg and Leu compared to the ones fed low-protein diet unsupplemented. Regarding normal protein diets, marbling and IMF content in loin were reduced when arginine was supplemented. Supplementing normal-protein diets with arginine also reduced belly weight and increased lean meat percentage, while Leu supplementation had no effect on carcass characteristics. Opposing previous research and contrary to the initial hypothesis, reduction of CP and dietary supplementation with leucine had no effect on intramuscular fat content, as regards arginine, IMF was even reduced.
Tous, Núria, Rosil Lizardo, Borja Vilà, Marina Gispert, Maria Font-i-Furnols, and Enric Esteve-Garcia. 2017. Addition of arginine and leucine to low or normal protein diets: performance, carcass characteristics and intramuscular fat of finishing pigs. Spanish Journal of Agricultural Research 14, No. 4: 0605. https://doi.org/10.5424/sjar/2016144-9351