Influence of dietary methionine to methionine plus cysteine ratios on nitrogen retention in gilts fed purified diets between 40 and 80 kg live body weight

Abstract

. 2007. Influence of dietary methionine to methionine plus cysteine ratios on nitrogen retention in gilts fed purified diets between 40 and 80 kg live body weight. Can. J. Anim. Sci. 87: [87][88][89][90][91][92]. The relationship between the ratio of available methionine (MET) to methionine plus cysteine (TSAA) intake and wholebody protein deposition (PD) was established using the nitrogen (N) balance technique in gilts between 40 and 80 kg live body weight (BW), according to a repeated 5 × 5 Latin square design. Pigs were fed casein-and cornstarch-based diets that supplied equal moles of TSAA supporting a PD of approximately 80% of the gilts' PD potential. On a weight basis, the target ratios of MET to TSAA were 42, 47, 52, 57 and 67% for the five experimental diets, respectively. This calculated to 37, 42, 47, 52 and 62.5% on a molar basis. Total N excretion (urine plus feces) was reduced (linear; P < 0.001) and PD was increased (linear; P < 0.001) when the available MET to TSAA ratio was increased to 52%; these values did not change (P > 0.05) when the MET to TSAA ratio was further increased. A number of statistical models were fitted to the data to establish the best fit of the model parameters. The greatest proportion of the variation (R 2 = 0.990) was explained with an asymptotic model; based on this model the optimum available MET to TSAA ratio (supporting 90% of the asymptotic value for PD) was 55% on a weight basis or 50.5% on a molar basis. The results indicate that the minimum contribution of available MET to TSAA requirements of growing pigs is higher than the value currently suggested by the National Research Council (46 to 48% on a weight basis). Les sujets ont reçu des rations à base de caséine ou de fécule de maïs qui fournissaient une quantité molaire identique de TSAA conduisant à un PD égal à environ 80 % du PD potentiel des animaux. Exprimé en fonction du poids, le ratio visé entre la MET et la TSAA s'établissait respectivement à 42, 47, 52, 57 et 67 % pour les cinq expériences, soit 37, 42, 47, 52 et 62,5 % en valeur molaire. Les auteurs ont observé une baisse de l'excrétion totale de N (urine et fèces) (linéaire; P < 0,001) et une hausse du PD (linéaire également; P < 0,001) quand le ratio entre la MET disponible et la TSAA passe à 52 %; ces valeurs restent identiques (P > 0,05) quand le ratio entre la MET et la TSAA continue de s'accroître. Les auteurs ont appliqué les données à plusieurs modèles statistiques en vue d'établir celui qui accepterait le mieux les paramètres. Un modèle asymptotique explique la majeure partie de la variation (R 2 = 0,990); selon ce modèle, le ratio optimal entre la MET et la TSAA (à savoir celui qui explique 90 % de la valeur asymptotique du PD) est de 55 % en poids ou de 50,5 % en valeur molaire. Les résultats indiquent que la contribution minimale de la MET aux besoins de TSAA des porcs en croissance est supérieure à ce que suggère actuellement le National Research Council (46 à 48 % selon le poids).

Impact of immune system stimulation on the ileal nutrient digestibility and utilisation of methionine plus cysteine intake for whole-body protein deposition in growing pigs

“…It has been shown that the efficiency of SAA utilisation for PD is affected by dietary AA balance ( 34 ) . In a previous study ( 33 ) , it has been confirmed that SAA were among the first-limiting AA in the dietary AA profile that was used in the present study.…”

“…To our knowledge, this is the first attempt to evaluate SAA requirements and ileal digestibility of nutrients during ISS in growing pigs. In the present study, serial dilution of dietary protein sources was used to generate the dietary treatments and to avoid confounding of SAA intake levels with changes in dietary AA balance ( 33 ) . It has been shown that the efficiency of SAA utilisation for PD is affected by dietary AA balance ( 34 ) .…”

Optimum proportion of standardized ileal digestible sulfur amino acid to lysine to maximize the performance of 25-50 kg growing pigs fed reduced crude protein diets fortified with amino acids

“…Shoveller et al (2003) found that when Met is meeting 100% of the SAA requirement, Cys can replace 40% of the Met requirement. More recently, Gillis et al (2007) and Qiao et al (2008) suggested an optimal proportion of Met to SAA of 55.0% for growing pigs. In the basal diet of the current study, the SID Met : Cys ratio was 53 : 47 which is similar to the ratio that Yi et al (2006) used to determine the SID SAA requirement for nursery pigs.…”

Amino acid requirement of growing and finishing pigs

“…Regarding the optimal ratio of methionine to SAA, Gillis et al (2007) suggested an optimal ratio of 55.0% for 40-80 kg growing gilts. They investigated this ratio in relation to protein deposition using the nitrogen (N) balance technique.…”