Improving feed efficiency is a key factor in livestock systems to reduce feeding costs and enhance profitability (Baker et al., 2006), and it is also associated with beef production sustainability (Kenny et al., 2018). Residual feed intake (RFI) is one of the traits used to assess feed efficiency of both growing and finishing beef cattle, which is defined as the difference between actual and expected feed intake of an animal based on its level of production (Koch et al., 1963). The moderate heritability of RFI and its independence of performance traits, in comparison with other feed efficiency metrics, has contributed to becoming a trait of preference for improving feed efficiency by genetic selection (Herd and Bishop, 2000; Arthur et al., 2001; Pravia et al., 2022). This trait has been incorporated into the genetic evaluation of the Uruguayan Hereford breed, and the expected phenotypic independence was also confirmed at the genetic level in Hereford, in which non or negligible unfavorable phenotypic and genetic correlations were found with growth performance traits (Pravia et al., 2022). Comparisons of efficient and inefficient animals indicate significantly lower feed intake in efficient individuals with a difference of around 15% to 20% during growing and fattening at similar levels of performance (McGee et al., 2014; Kenny et al., 2018; Pravia et al., 2018, Silveira, 2023). This implies important savings in terms of feed costs and a favorable effect on profitability if carcass and meat quality are not negatively affected. Thus, it is pivotal to know the relationship between RFI and carcass and meat quality characteristics. Previous studies have not shown consistent evidence about the phenotypic association between RFI and meat quality characteristics, (Herd and Bishop, 2000; Baker et al., 2006; Cruz et al., 2010; Zorzi et al., 2013; Herd et al., 2014; Nascimento et al., 2016; Pravia et al., 2018) most likely because different populations respond distinctly to classification for RFI (Meale et al., 2021).

The aim of the present study was to evaluate the association between RFI at finishing and carcass and beef quality traits of Hereford steers.

The three groups of steers did not differ (P > 0.05) in SW, HCW, carcass yield, marbling scores, REA, and FAT (Table 3). In addition, no differences (P > 0.05) were observed in meat quality attributes: meat color (L*, a*, and b*), CL, and WBSF among HRFI, MRFI, and LRFI steers (Table 3). A significant (P < 0.05) year effect was found in almost all the carcass and meat quality characteristics that could be associated with different diets between years during the experimental period. Regardless, there were no significant (P > 0.05) interactions between year and RFI group for any of the carcass and meat quality traits. There were only significant differences (P < 0.05) among RFI groups for the top sirloin and the inside round; all other valuable cuts were similar (P > 0.05) among RFI groups. Steers from LRFI and MRFI had heavier (P < 0.05) top sirloins than HRFI animals. Inside round from more efficient animals (LRFI) were heavier (P < 0.05) than HRFI steers (Table 4). As observed for carcass and meat quality traits, there was a significant effect of year on the weight of most cuts; however, there was not a significant interaction of year × RFI for any of the evaluated cuts (Table 4).

Steers from HRFI showed a greater (P < 0.05) proportion of IMF than LRFI animals (Table 5). When significant differences (P < 0.05) were observed in the fatty acid concentrations, greater (P < 0.05) contents were found in meat from HRFI than in LRFI steers, except for C14:0 and C22:6-n3. Longissimus muscles from HRFI steers presented greater (P < 0.05) concentrations of SFA, MUFA, and PUFA than those from MRFI and LRFI animals. The PUFA/SFA ratio of IMF did not differ (P > 0.05) between LRFI and HRFI steers and neither between LRFI and MRFI. In addition, the omega 6:omega 3 fatty acids ratio was similar (P > 0.05) among the 3 RFI groups (Table 5).

Tenderness, flavor, and overall liking acceptability mean scores were not significantly different (P > 0.05) among meat samples from LRFI, MRFI, and HRFI steers (Table 6). It is important to highlight that the 3 groups of RFI were scored positively (i.e., at least “I like slightly”) for the 3 attributes.

As reported in previous studies carcass characteristics such as HCW, carcass yield, marbling scores, REA, and fat thickness were not affected by RFI (Baker et al., 2006; Castro Bulle et al., 2007; Cruz et al., 2010; Gomes et al., 2012; Zorzi et al., 2013; Pravia et al., 2018). Nevertheless, Robinson and Oddy (2004) reported that selection for reduced RFI is likely to decrease subcutaneous fat thickness. Herd et al. (2014) found that HRFI steers had a greater depth of subcutaneous rib fat than LRFI. These authors indicated that fat deposition pattern changes in LRFI animals toward more intermuscular fat and less subcutaneous fat; however, our results do not support these findings. Heavier top sirloin and inside round were found in LRFI steers than in HRFI animals, but no differences were observed in the weights of any of the other cuts. Zorzi et al. (2013), when working with Nellore bulls, did not find differences in the weights of the strip loin, tenderloin, and complete rump between high and low RFI animals. Bonilha et al. (2013) reported no differences in the percentage of edible part of carcass between low and high RFI Nellore bulls. Results from the present study showed that significant differences among RFI groups were found just for the weight of two cuts whose magnitude (less than 4% difference) lacks practical relevance for the meat industry. Selection for more efficient animals (LRFI) would not have any detrimental effect on the weights of retail cuts.

Tenderness is considered the most relevant attribute influencing consumer satisfaction and beef palatability (Dikeman, 1987; Miller et al., 1995; Maltin et al., 2003; Van Wezemael et al., 2014). It has been suggested that selection for more efficient animals could be negatively associated with meat tenderness (Herd and Pitchford, 2011) and may be related to a lesser degradation of myofibrillar proteins (Gomes et al., 2012). Some studies have shown greater shear force values on aged (Zorzi et al., 2013) and non-aged meat (Herd et al., 2014; Nascimento et al., 2016) from more efficient (low RFI) animals; however, in our study, meat shear force was not affected by RFI, which agrees with previous research (Baker et al., 2006; Ahola et al., 2011; Gomes et al., 2012; Blank et al., 2017; Pravia et al., 2018). It is important to note that all shear force values of meat, even those aged for 5 d, were below 4.1 kg, indicating that it was tender beef that would guarantee high acceptability by consumers (Huffman et al., 1996). This was confirmed to some extent by consumers since the mean tenderness scores of the three RFI groups were at least “I like slightly.” Cooking losses were not different across RFI groups, which were in agreement with the findings of previous studies (Ahola et al., 2011; Herd et al., 2014; Blank et al., 2017). Beef color represents the most important factor that affects consumers purchase decision (Faustman and Cassens, 1990; Mancini and Hunt, 2005). Lack of beef cherry-red color or discoloration may reduce consumer’s willingness to purchase. Values of L*, a*, and b* coordinates of meat color were not different among RFI groups in our study and similar results were also found in unaged (Perkins et al., 2014) and aged meat for 7 and 14 d (Nascimento et al., 2016). However, Baker et al. (2006) found greater b* (yellowness) values of lean color in high compared to mid- and low-RFI steers. In addition, Herd et al. (2014) observed greater L*, a*, and b* values on meat aged for 7 d in high compared with low-RFI Angus steers, although those differences were small in magnitude. We could infer that inconsistencies in objective meat color measurements would indicate no clear association between RFI and beef color.

Intramuscular fat content is a relevant characteristic that influences meat tenderness, juiciness, and flavor, affecting beef palatability (Smith et al., 1985; O’Quinn et al., 2012; Emerson et al., 2013; Corbin et al., 2015; Frank et al., 2016). Furthermore, there is growing interest in the nutritional aspects and health implications of meat consumption, particularly associated with its fat content (Daley et al., 2010). In our study, even though no differences were observed in the marbling scores across RFI groups, inefficient steers (HRFI) presented a greater IMF content than LRFI animals, which agrees with the findings of Nascimento et al. (2016) in Nellore steers. Nevertheless, some studies did not find differences in the IMF content across RFI groups of Bos taurus (McDonagh et al., 2001) and Bos indicus (Gomes et al., 2012) steers. Previous studies that evaluated the relationship between RFI and IMF seem to be inconclusive (Welch et al., 2012). Regarding fatty acid composition, meat from HRFI steers showed greater concentrations of SFA, MUFA, and PUFA than LRFI, which was related to the greater IMF content. Rauw et al. (2012) worked with barrows, and they observed that the correlations between RFI and fatty acid profile became non-significant after correction for IMF. In Japanese Black cattle, Inoue et al. (2011) found that RFI has less of an effect than feed conversion ratio on the fatty acid composition of intramuscular fat. These authors reported positive but low genetic correlations (0.06 to 0.17) of oleic acid (C18:1), MUFA, and the SFA to MUFA ratio with RFI.

Evaluating meat-eating quality is of primary relevance to understanding the acceptance of meat products and in this scenario, consumer sensory studies are increasingly used (Miller, 2020). Tenderness, juiciness, and flavor are the 3 attributes influencing cooked meat palatability and are linked to consumer satisfaction (Garmyn, 2020). In the present study, consumer panel scores for tenderness, flavor, and overall liking of steaks did not differ across RFI groups. Ahola et al. (2011) reported an absence of a relationship between RFI, and tenderness, juiciness, flavor, off-flavor, and overall acceptability of steaks from Angus steers evaluated by a trained sensory panel. In the same line, Baker et al. (2006) did not find differences in tenderness and flavor of steaks from Angus steers across RFI groups scored by trained panelists. Therefore, our findings and previous studies with British breeds have not found any relationship between RFI and sensory attributes.

The findings of the present research indicate that RFI would not be related to carcass traits and meat quality of Hereford steers. The current study detected differences in the IMF content and fatty acids concentrations, but those differences did not affect palatability attributes scored by consumers. The inclusion of RFI in genetic selection programs would have a positive impact on reducing feed costs, among others, with minor or no detrimental effect on end-product quality.