The amino acid composition of tissue protein is affected by the total sulfur amino acid supply in growing pigs

Abstract

The factorial approach to assess the amino acid (AA) requirements of pigs is based on the assumption that the AA composition of body protein is constant. However, there are indications that this assumption may not be valid because the AA composition of body protein can be affected by the AA supply. The extent to which different tissues are affected by an AA deficiency is unknown. The objective of this study was to investigate the effect of feeding pig diets with a deficient or sufficient total sulfur AA supply (TSAA; Met + Cys) from 6 to 23 weeks of age on tissue composition and meat quality. The deficient diet (TSAA-) provided 24% Met : Lys and 51% TSAA : Lys on a standardized ileal digestible basis, which are 19% and 16% below the recommended requirements, respectively. The sufficient diet (TSAA + ) provided 33% Met : Lys and 60% TSAA : Lys. Diets were offered slightly below the ad libitum feed intake capacity of the pigs. Pigs offered diet TSAA-had a lower average daily gain, lower weights of the longissimus dorsi (LM) and rhomboideus muscles (RM), and of selected skin sections (P < 0.05). The weight of different sections of the small intestine and the liver was not affected by the diet. The protein content of the LM and RM decreased in pigs offered diet TSAA-(P < 0.05), whereas the protein content of other tissues was not affected. The TSAA supply affected the AA composition (g/16 g N) of protein in all tissues, but the Met content was changed only in the liver (P < 0.05). Pigs receiving diet TSAA-had a lower Cys content in the RM and in the distal jejunum and ileum (P < 0.01). The deficient TSAA supply resulted in a lower carcass weight and higher muscle glycogen stores (P < 0.05), but did not affect other meat quality traits. The results of this study indicate that the muscles, jejunum and ileum respond more to a prolonged AA deficiency than the liver. In addition, the observed changes in AA composition of tissue protein question the use of a constant AA profile of retained protein to assess AA requirements.

Skeletal muscles respond differently when piglets are offered a diet 30 % deficient in total sulfur amino acid for 10 days

“…The proportion of type I fibers varied from less than 2 % in white SM to more than 50 % in RM, and type IIB fibers from less than 20 % in RM to more than 80 % in LM and white SM, in agreement with the existing literature [28]. The His concentration was lower in RM than in other muscles, which is in agreement with previous data from our laboratory [17]. This is also consistent with the higher concentration of carnosine in LM than in the mixed slow-and fast-twitch oxidative trapezius muscle [1].…”

“…This is consistent with previous work from our laboratory [16,17] and reported differences between LM and the semimembranosus muscle in pigs [46]. Because fiber types have different contractile and metabolic properties [39], differences in AA composition among muscles may be related to differences in the composition of fiber types.…”

“…A limiting TSAA supply affected the concentration of AA such as Met, His, and the BCAA in muscle protein, confirming results from previous studies [16,17]. Although Chang and Wei [13] reported that the AA composition of four different muscles was not changed in pigs fed a Lysdeficient diet, the lack of response may have been due to the moderate AA deficiency used.…”

“…In previous studies, we showed that a deficient TSAA diet changed the AA composition of whole body proteins, with a strong effect on the longissimus muscle (LM; [16,17]. Changes in muscle mass can be explained by a change in the balance between protein synthesis and protein degradation.…”

Effects of chromium supplementation on growth, nutrient digestibility and meat quality of growing pigs

“…Cai et al (2010) and Conde-Aguilera et al (2014) reported high contents of glutamic acid, aspartic acid, lysine, leucine and arginine in the longissimus dorsi muscle of pigs, which is similar to the current results. Evans & Bowman (1992) showed that Cr supplementation in rat diets led to an increased uptake of glucose and amino acids in the skeletal muscle.…”