Effect of Supplementary Levels of Rumen-Protected Lysine and Methionine on Growth Performance, Carcass Traits, and Meat Quality in Feedlot Yaks (Bos grunniens)

Abstract

Yak, a unique bovine species on the Qinghai-Tibetan Plateau, has provided pastoralists with the basic materials of production and life for thousands of years. Existing literature showed that yak meat is of high nutritional value for humans whereas the growth performance is relatively low. As it has been demonstrated, lysine and methionine are the two key limiting amino acids in ruminants. Therefore, this study was conducted to investigate the effect of supplementary levels of rumen-protected lysine (RPL) and methionine (RPM) on growth performance, carcass traits, and meat quality in feedlot yaks. Thirty-two male yaks, with initial body weight (IBW) of 237.5 ± 13.99 kg were randomly assigned to four dietary treatments (n = 8), including control group (CON; basal diet without adding rumen-protected amino acid (RPAA)), low RPAA supplementation group (Group Low; basal diet supplemented with RPL (30.0 g/animal/day) and RPM (7.5 g/animal/day)), medium RPAA supplementation group (Group Medium; basal diet supplemented with RPL (50.0 g/animal/day) and RPM (12.5 g/animal/day)), and high RPAA supplementation group (Group High; basal diet supplemented with RPL (70.0 g/animal/day) and RPM (17.5 g/animal/day)). The average daily gain was increased linearly (p < 0.001) and quadratically (p < 0.01) while feed to gain ratio was decreased linearly (p < 0.001) and quadratically (p < 0.001) with the increasing RPAA supplementation, and the average daily gain was higher while feed to gain ratio was lower in RPAA than CON (p < 0.001). Meat color L* values and b* were decreased linearly (p < 0.01) with the increase of RPAA supplementation, and b* was lower in RPAA than CON (p < 0.05). Meat color a* value was increased linearly (p < 0.05) with the increasing RPAA supplementation, and a* was higher in RPAA than CON (p < 0.05). The 24 h drip loss and shear force were decreased quadratically (p < 0.01) with the increasing RPAA supplementation, and drip loss and shear force values were lower in RPAA than CON (p < 0.05). The glycine concentration in longissimus dorsi (LD) increased linearly (p < 0.05) with the increasing RPAA supplementation. These results demonstrated that both the growth performance and meat quality characteristics were improved in feedlot yaks as an effect of the dietary supplementation with RPL and RPM, and the medium supplementary level is recommended, since it showed the most promising results.

Effect of supplementing lysins and methionine to low-protein diets on growth performance, hepatic antioxidant capacity, immune status, and glycolytic activity of tibetan sheep

“…4 Protein-protein interaction (PPI) network. Red represents the core genes, Blue represents differentially expressed genes Met supplementation in feedlot Yaks [17]. In the present study, the final body weight with Lys/Met at ratio 1:1 was increased of Tibetan sheep.…”

Effect of the inclusion of rumen-protected amino acids in the diet of growing beef cattle on animal performance and meat quality

“…The increased metabolizable Lys balance may have impacted performance if other AAs were imbalanced. Ma et al (2021) observed differences in the ADG and feed-to-gain ratio in yaks in a feedlot with four supplementary levels of RP-Lys and Met in the diets. They concluded that growth performance and meat quality could be improved by supplementing RP-AAs in the diets.…”

“…Heiderscheit and Hansen (2020) reported no differences in the carcass characteristics of Angus crossbred steers fed supplemental RP-Lys diets. Similarly, Ma et al (2021), in their study with different levels of protected Lys and Met, found no differences in carcass characteristics. In diets with varying levels of CP and Lys-to-Met ratios, Prado et al (2014) did not observe significant differences in carcass conformation and fatness score.…”

Integrated metabolome and microbiome analysis reveals the effect of rumen-protected sulfur-containing amino acids on the meat quality of Tibetan sheep meat

“…In their study of meat tenderness, Haiqing et al found that adding different concentrations of RPMET to the diet of Tan sheep did not significantly affect the SF ( Li et al, 2020 ). In fact, the study by Zhiyuan et al showed that low to medium concentrations of RPLYS and RPMET significantly reduced the SF of yak meat ( Ma et al, 2021 ). On the other hand, in this study, the addition of RPSAA was found to significantly increase the SF of Tibetan sheep meat.…”

“…In this case, RPAA can reduce the degradation within the rumen, thereby allowing the amino acids to enter the small intestine. This not only improves the utilization rate of amino acids but also increases animal production ( Ma et al, 2021 ; Liu et al, 2023 ). However, RPAA decomposed in the rumen and entering the small intestine may also alter the gastrointestinal microbiota.…”