Bioavailability of L-Methionine in comparison to DL-Methionine for nitrogen retention of weaned and growing pigs

• Published in: Journal of animal science Vol. 97; p. 66
• Main Authors: Caetano, Raphael P, Santos, Luan S, Htoo, John K, Veira, Alini M, Silva, Welex C, Gobi, Jaqueline P, Fraga, Alicia Z, Campos, Paulo H R F, Barbosa, Nei A A, Hauschild, Luciano
• Format: Journal Article
• Language: English
• Published: Champaign Oxford University Press 01.07.2019
• Subjects: Balance studies; Bioavailability; Comparative analysis; Confidence intervals; Corn; Diet; Dietary supplements; Methionine; Nitrogen; Parameter estimation; Retention; Soybeans; Statistical analysis; Weaning
• ISSN: 0021-8812; 1525-3163
• DOI: 10.1093/jas/skz122.122

Two nitrogen (N) balance studies were conducted to compare the relative bioavailability (RBV) of L-Met with DL-Met as Met sources in young pigs. In each experiment, 42 barrows (PIC; initial BW in Exp. 1: 10.7 kg and Exp. 2: 20.5 kg) were allotted to 7 experimental diets with 6 pigs per treatment. The basal diets (diet 1) were formulated based on corn and soybean meal being deficient in Met, but adequate for the other AA (Exp. 1: 0.24% standardized ileal digestible [SID] Met; 0.53% SID Met + Cys; 1.30% SID Lys; Exp 2: 0.23% SID Met; 0.47% SID Met + Cys; 1.15% SID Lys). Three graded levels of DL-Met and L-Met (0.03, 0.06 and 0.09%) were supplemented to the basal diet on top to create diets 2 to 7 for both studies. In Exp.1, N retention (% of N absorbed) increased linearly (P < 0.05) with supplementation with both Met sources. The slope-ratio regression estimated the RBV of 106% [95% confidence interval (CI): 39 to 173%] for N retention (% of absorbed) on an equi-molar basis. In Exp. 2, N retained (g/d), N retention (% of N intake and % of N absorbed) increased linearly (P < 0.05) by supplementing with both Met sources. There was no effect of Met sources on all N balance parameters in both studies. The slope-ratio estimated the RBV of 89% (95% CI: -28 to 206%) for N retained (g/d), 95% (95% CI: 13 to 177%) for N retention (% of N intake) and 94% (95% CI: 20 to 167%) for N retention (% of N absorbed), respectively on an equi-molar basis. In conclusion, the 95% CI for the RBV of L-Met covers 100%, indicating the RBV of L-Met is not different from that of DL-Met as a Met source for weaned and growing pigs.