OH-Methionine and DL-Methionine: Same efficacy to sustain Piglets’ performance

A trial at ISMADE (a Spanish research center in animal nutrition) showed clearly that DL-Methionine and DL-hydroxy-methionine (liquid or powder forms) are 100% efficient to sustain piglets’ growth during the post weaning period from day 28 to day 70.

The study was performed on 720 piglets (crossbreed female largewhite*landrace x male pietrain*duroc): 360 females and 360 males, reared from 28 to 70 days-old. Piglets were weaned at 28 days and randomly allocated to 6 treatments with 12 pens of 10 piglets each. Diets were based on wheat, corn, barley and soybean meal and formulated according to the recommendations of FEDNA (deBlas et al., 2010) for all amino acids except for Total Sulfur Amino Acids (TSAA) which varied depending on the experimental treatments. Three treatments were formulated to reach the required SID TSAA/Lys ratio of 58%, supplemented either with DL-Methionine, liquid OH-Methionine or the formulation of OH-Methionine calcium salt and liquid OH-Methionine at incorporation rates allowing equimolar supply. The last three diets consisted to supply the three methionine sources at 125% of TSAA requirement. During the whole experimental period, piglets had free access to feed and water. Piglets’ body weights were measured at day 28, day 49 and day 70. Mortality was monitored. Feed Conversion Ratio or Average Daily Gain were calculated on the total experimental period (42 days).

Body weight increased with age as expected and reached a final value at day 70, in line with the expected weight around 22-24 kg for these breeds. Females and males also had a similar body weight at the different time of measurements. No significant difference of performance was observed between methionine sources during the different feeding periods. No interaction between methionine sources, level or sex were observed, validating the fact that these three methionine sources can be used equally for post-weaning piglets (Table 1).

In this study, two doses of methionine corresponding respectively to TSAA recommendations (NRC 2012) and a level at 125% TSAA, above requirements, were studied. Interestingly, these levels resulted in a significant effect on Feed Conversion Ratio for the first post-weaning period from day 28 to day 49. The methionine level effect was in interaction with the piglets’ sex (Graph 1) and showed that the increase on methionine level was beneficial for males but not for females. This effect can be related to the physiological difference between males and females even if at this age, it did not appear significantly on performances. Feed intake was really close between males and females for this period and it can be hypothesized that an increase of TSAA allowed male piglets to improve their efficiency. The effect on FCR for males was high with 12% difference between the two doses. This result suggested that, for the first post-weaning period, more attention on TSAA supplementation should be given to males’ diets. However, this methionine level effect was not observed during the second and the whole rearing period. This suggested that NRC recommendations in TSAA for the second post weaning period are more in line with piglets’ requirements, contrary to the first period. The piglets’ body weight homogeneity (not shown) was not significantly affected by any of the tested factors.

The study showed the 100% efficacy of methionine sources. It also underlined the benefits of increasing methionine doses during the post-weaning period for male piglets, as they exhibited a significantly improved Feed Conversion Ratio (12% FCR improvement for a diet at 125% TSAA compared to 100% TSAA). This suggests potential economical saving considering the high price of ingredients included in the diet of this specific period (i.e. whey powder).