Phenotypic relationships between meat quality parameters and residual feed intake in Japanese black Wagyu cattle.

ABSTRACT

Japanese black Wagyu cattle are renowned for producing some of the world's most highly valued and recognized beef with exceptional marbling. Therefore, the primary focus of genetic selection for Wagyu cattle has historically been on meat quality, particularly achieving high marbling levels. However, even when the price of the final product is high, production costs also remain high, especially considering that most of the feed has to be imported. The objective of this study was to evaluate phenotypic relationships between feed efficiency, specifically residual feed intake (RFI), as the most utilized efficiency index in cattle, and various meat quality parameters in Japanese black cattle in order to determine if a common phenotypic selection for these parameters could be feasible. For this, a total of 39 Wagyu cattle were evaluated for feed efficiency over their entire fattening period (900 d), with a focus on RFI as a key indicator. Animals were fed high-starch diets with vitamin A deprivation to achieve the desired marbling. Results revealed positive correlations between feed efficiency and meat quality in Wagyu cattle. Specifically, animals with higher feed efficiency exhibited superior meat quality traits, including firmness, marbling, and overall meat rating. When comparing the 20 most extreme RFI individuals (10 most and 10 least efficient), we observed that efficient RFI animals showed increased marbling levels (+13.2%, P = 0.05) and ranking quality (+12%, P = 0.06) of the meat. In conclusion, this research contributes to understanding the interplay between feed efficiency and meat quality in Japanese black Wagyu cattle. Phenotypic correlations observed suggest the possibility of incorporating RFI criteria into genetic selection programs without compromising the prized meat quality traits of Wagyu beef.

The Japanese black cattle, or Wagyu, are known because of its exceptional meat quality and its high degree of marbling. However, to achieve this condition, animals are fed with high amount of concentrate and over long periods of time. In order to decrease both environmental impact and economic profitability of Wagyu producers, feed efficiency may be improved. Therefore, the present work evaluates the phenotypic relationship between meat quality variables of Japanese black cattle and their efficiency of feed utilization. Results showed how individuals with improved efficiency of feed utilization present higher degree of marbling than non-efficient, which may represent the footprint of a new genetic selection program which encompasses both meat quality criteria and feed efficiency values. These results have to be confirmed by genetic studies to verify heritability of these treatments.