LAUSR

This work aimed to compare piglet’s performance when fed DL-Methionine or Hydroxy-Methionine (OH-Met and OH-MetCa) at the requirements of sulfur amino acids (SAA) or above. 720 piglets (♀ large white*landrace x ♂ pietrain*duroc) were weaned at 28 days old (6.84 ± 1.07 kg) and randomly allocated to the experimental treatments for 42 days. The experiment was a factorial design with three Met sources (DL-Met, liquid OH-Met (acid form) or OH-MetCa under powder form) and two doses of SAA. Treatments were formulated to reach the adequate SID SAA/Lys ratio of 58% or exceeded the Spanish nutrient recommendations in SAA by 25% (0.79% SID SAA/Lys). Each treatment was replicated 12 times (6 pens of males and 6 pens of females). Growth performance was measured and data was analysed by mixed-effects models (R Core Team). The body weight was neither affected by SAA level, nor by the Met sources. The daily weight gain (DWG) was not affected by the dietary treatments from 0 to 21 days; whereas the feed conversion ratio (FCR) was significantly (P=0.01) improved when the SAA level was increased by 25% (1.272 and 1.184) due to the decreased feed intake (P=0.03). Significant interactions were found between the Sex and the SAA level for DWG (P = 0.04) and FCR (P = 0.03) from 0 to 21 days. From day 21 to 42 and from day 0 to 42, no performance criteria were different in all dietary treatments. For all criteria of performance, the three Met sources exhibited a similar response. These results confirmed that Met sources are equivalent in piglets.