Influence of the methionine:cysteine relationship in the feed on the performance of growing pigs

Abstract

Zusammenfassung Einfluß der Methionin: Cystin‐Relation des Futters auf die Leistung von wachsenden Schweinen In einem Mastversuch mit 8 × 12 Schweinen wurde der Einfluß eines unterschiedlichen relativen Met‐Anteils von 36, 40, 45, 50, 55, 60 und 64% (Gruppe II‐VIII) bei konstanter Gesamtversorgung an S‐haltigen Aminosäuren im Futter untersucht: Dazu wurden zu einer Met + Cysarmen Basisration (Gruppe I) alternativ DL‐Methionin, L‐Cystin oder Kombinationen von beiden zugesetzt. Im Abschnitt 30–60 kg und 60–90 kg Lebendgewicht betrug der Basalgehalt 0,38 bzw. 0,30% Met + Cys (50:50), die Gesamtversorgung von 0,53 bzw. 0,42% Met + Cys war jeweils knapp bedarfsdeckend. Mit steigendem relativen Met‐Anteil im Futter wurden Zuwachsrate, Futterverwertung, Rückenmuskelfläche und Fleisch‐Fett‐Verhältnis signifikant verbessert. Die maximale Leistungsverbesserung bei Zuwachsrate und Futterverwertung wurde anhand quadratischer Funktionen bei einem relativen Met‐Anteil von 55–57% abgeleitet. Bei dem ermittelten hohen Leistungsniveau von mehr als 800 g täglicher Zuwachsrate wird ein Mindestanteil von 55 % Met der S‐haltigen Aminosäuren empfohlen, der damit höher liegt als in früheren Untersuchungen. Die Ergebnisse verdeutlichen, daß eine sichere Bedarfsdeckung an S‐haltigen Aminosäuren erst durch den Mindestanteil an Met gewährleistet wird.

Maximal portion of the young pig's sulfur amino acid requirement that can be furnished by cystine

“…The Cys replacement value may be higher for older pigs, because they have a higher maintenance Cys requirement than do younger pigs (Baker et al, 1966;Roth and Kirchgessner, 1987). Roth and Kirchgessner (1989) suggested that 55 to 57% of the SAA requirement of 30-kg pigs must be furnished by Met to achieve maximal performance. In their study, however, the dietary Met:Cys weight ratio of 45:55 clearly produced weight gains similar to those produced by the 55: 45 ratio.…”

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

“…These authors concluded that determination of the requirement for TSAA was possible only after the supply of a minimum amount of MET. In a follow-up study to investigate this minimum proportion of MET, Roth and Kirchgessner (1989) fed pigs between 30 and 60 kg and 60 and 90 kg BW diets that contained MET at 36,40,45,50,55,60 or 64% (on a weight basis) of the total supply of TSAA in the diet, while maintaining the TSAA content slightly below the estimated requirement. Roth and Kirchgessner (1989) reported significant improvements in growth rate, feed conversion, area of eye muscle, and meat:fat ratio with a rising proportion of MET in the diet, with the optimum proportion of MET to TSAA being 55-57% based on a quadratic relationship.…”

“…In a follow-up study to investigate this minimum proportion of MET, Roth and Kirchgessner (1989) fed pigs between 30 and 60 kg and 60 and 90 kg BW diets that contained MET at 36,40,45,50,55,60 or 64% (on a weight basis) of the total supply of TSAA in the diet, while maintaining the TSAA content slightly below the estimated requirement. Roth and Kirchgessner (1989) reported significant improvements in growth rate, feed conversion, area of eye muscle, and meat:fat ratio with a rising proportion of MET in the diet, with the optimum proportion of MET to TSAA being 55-57% based on a quadratic relationship. Fuller et al (1989) estimated that CYS could supply approximately 0.8 of the total TSAA needs for maintenance, which can be explained primarily by keratin synthesis (Mitchell 1950), and close to half the total TSAA needs for body protein accretion.…”

“…These authors surmised, therefore, that CYS, on a weight basis, could substitute for MET in supplying 54% of total TSAA needs of the pig. Furthermore, and given that the minimum proportion of MET required increases with an increasing level of performance due to the maintenance proportion decreasing relative to the pig's total TSAA requirement, Roth and Kirchgessner (1989) determined a theoretically optimum ratio of 60:40 MET:CYS, on a weight basis, in growing pigs for maintenance and protein accretion. This concurs with their experimentally determined optimum value.…”

“…Since MET can be converted to CYS, but not vice versa (Stipanuk 1986), it is feasible that a minimum dietary MET to TSAA ratio occurs in pig diets, at which MET and TSAA utilization for PD is maximized. Estimates of the minimum ratio between MET and TSAA vary and are affected by many factors including diet composition and amino acid sources, response criteria, pig body weight (BW), errors associated with chemical analysis, and total TSAA intake (Agricultural Research Council 1981;Roth and Kirchgessner 1989;Chung and Baker 1992;Kirchgessner et al 1994;NRC 1998). Unfortunately, in most of the experiments conducted to assess the optimum MET to TSAA ratio, relatively few ratios have been evaluated or animals have been fed on an ad libitum basis, which will confound effects between diet MET and CYS levels, feed intake and pig performance.…”