383 Performance of piglets in response to graded dietary supplementation of sulfur amino acids using either hydroxy-methionine or DL-Methionine during the post-weaning period
Authors: Eugenio Francis Amann , Gracia-Lorenzo Marta Isabel , Batonon-Alavo Dolores I , Mercier Yves 
Published: September 2024

Abstract
Providing piglets with their precise nutritional need is critical during the stressful post-weaning period. Methionine (Met), a sulfur-containing amino acid, has a crucial role in piglet growth and health. Stressful conditions may increase Met demand due to its involvement in maintaining redox balance via downstream metabolites such as glutathione. There are different sources of supplementary Met for pigs such as DL-methionine (DL-Met) and hydroxy-methionine. The latter comes mostly as an acidic liquid form (OH-Met) and to a lesser degree as a powder calcium-salt (OH-Met-Ca). This study investigates the effect of graded levels of dietary total sulfur amino acids (TSAA) by supplementing different sources of Met on the performance and capacity of post-weaning piglets to respond to stress. Two experiments were performed. In experiment 1, post-weaning piglets [n = 90; 28 d of age; body weight (BW) = 9.13 ± 0.65 kg] were fed with either DL-Met or OH-Met-Ca to provide 80%, 100%, and 125% TSAA recommendations of NRC and performance parameters were measured for 41 d. Treatments were replicated nine times, and blocking was done according to initial BW. For experiment 2, 720 post-weaning piglets (n = 720; 28 d of age; BW = 6.84 ± 1.07 kg) from three consecutive breeding batches were fed with either DL-Met, OH-Met, or OH-Met-Ca at or above (100% or 125%) TSAA requirements of FEDNA. Performance parameters and oxidative status through various plasma indicators were measured. Treatments were replicated 12 times. Data from both experiments were analyzed separately using a mixed effect model with Met source and level as fixed effects (and their interaction in experiment 2) and blocks and batch as random effects for experiments 1 and 2, respectively. In experiment 1, piglets fed 80% of TSAA requirement showed the least average daily weight gain, while those fed OH-Met-Ca at 100% or DL-Met at 125% requirement had the greatest BW gain among the treatments (P &lt; 0.01). Feed conversion ratio was best for piglets fed with OH-Met-Ca at 100% requirement, while animals fed with 80% requirement were the least efficient (P = 0.04). Contrasts showed no differences between Met sources (P ≥ 0.51) and level of TSAA (P ≥ 0.56) for any of the parameters. Meanwhile in experiment 2, there were no interactions between Met source and TSAA level (P &gt; 0.10). The Met source did not affect any parameter (P ≥ 0.14). However, there was a significant decrease in daily feed intake when piglets were fed above requirements (P = 0.02), and a significant increase in the concentration of plasma glutathione peroxidase when piglets were fed at TSAA requirements (P &lt; 0.05). These results suggest that post-weaning piglet performance and oxidative status can be sustained regardless of the Met source tested. Feeding healthy and unchallenged piglets with excess dietary Met may not bring extra benefits.