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The feeding system is one of the main factors influencing the meat quality of the Iberian. In this sector it is generally assumed that substitution of traditional free-range rearing, with acorns and grass, by mixed diets has an impact on intramuscular fat content and fatty-acid composition, causing a decrease in meat quality. Mixed diets are usually formulated with higher protein contents than those supplied by natural resources consumed by Iberian pigs fed extensively. For that reason, this study hypothesized that the use of a low-protein diet in the final fattening period of the pig could be a suitable strategy to improve meat and dry-cured product quality. Therefore, the aim of this study was to evaluate the influence of feeding diets containing different levels of protein on the performance, carcass, and meat quality of Iberian pigs. For that purpose, 24 castrated male Retinto Iberian pigs with an average weight of 116 kg were fed under free-range conditions with acorns and grass (FR), and on concentrated diets in intensive conditions with standard (SP) and low protein content (LP). During the trial, pigs were weighed every week from the beginning of the fattening period to slaughter. The selection criterion for the slaughter was weight increase. Afterward, hams, shoulders, serratus ventralis, longissimus thoracis and lumborum were weighed and collected for the carcasses to perform the assessment.
As a result, FR pigs needed more time to achieve slaughter weight than LP and SP pigs. Iberian pigs fed on low-protein diet (FR and LP) had a higher intramuscular fat content in the musculus serratus ventralis than SP pigs. The influence of diet on the fatty-acid composition was reflected more markedly in subcutaneous fat than in muscles. FR pigs showed a higher level of C18:1n-9 and total polyunsaturated fatty acids and lower total saturated fatty acids in subcutaneous fat than LP and SP.
In conclusion, it was observed that Iberian pigs fed on low-protein diets had higher intramuscular fat content and different meat composition compared to pigs fed on concentrates with standard protein levels, which could be an interesting strategy to improve the Iberian pig meat and dry-cured product quality.
Tejeda JF, Hernández-Matamoros A, Paniagua M, González E. Effect of Free-Range and Low-Protein Concentrated Diets on Growth Performance, Carcass Traits, and Meat Composition of Iberian Pig. Animals. 2020;10(2): 273.