PHOTO: DICK VAN DOORN


A nutritional study was car- ried out at Huazhong Agri- cultural Univer- sity, China in or- der to compare the effective- ness of OH-Met to DL-Met in Cherry Valley ducks, as well as determining the bio-efficacy of the two sources.


production to ensure carcass quality. Many studies have re- ported that cysteine and methionine are involved in the syn- thesis of feather keratin and are important for feather growth. Cysteine is the major component of keratin and me- thionine is converted to cysteine. Conde-Aguilera et al. 2016 reported that in case of methionine restriction, feathering is maintained as priority for sulfur amino acid deposition prior to muscle. OH-Met is more efficiently converted to cysteine and taurine than DL-Met through the trans-sulphuration pathway. Cysteine is then converted to glutathione, that along with taurine, plays fundamental roles in antioxidant mechanisms and improves oxidative status. Therefore, OH-Met may have a higher value to ensure antioxidant capacity.


Table 2: Recommended levels of methionine and some nutritional para meters for Pekin ducks.


% nutrient 0-14 days NRC


(1994)


ME (MJ/kg) 12.1 CP 22 Lysine 0.90 Methionine 0.40


Adeola (2006)


12.0 21


0.96 0.55


Met+Cys 0.70 0.85 Threonine - 0.62


26


Grimaud Frères (2015) 12.1 20


1.00 0.50 0.85 0.75


15-49 days NRC


(1994)


12.5 16


0.63 0.3


0.55 -


▶ POULTRY WORLD | No. 1, 2019


Adeola (2006)


12.8 18


0.86 0.45 0.75 0.56


Grimaud Frères (2015) 12.8 17


0.8 0.4 0.7 0.6


Trial in Cherry Valley ducks A nutritional study was carried out at Huazhong Agricultural University, China in order to compare the effectiveness of OH- Met to DL-Met in Cherry Valley ducks, as well as determining the bio-efficacy of the two sources. The birds were fed diets supplemented with different levels of OH-Met and DL-Met to create eight experimental treatments; then compared to a ba- sal diet deficient in TSAA (Table 1). Starter (0-21 days) and grower (22-42 days) rations were based on corn, wheat and soybean meal and formulated according to NRC (1994) rec- ommendations. Feed intake of the basal diet was significantly different from the methionine-supplemented treatments, with no significant difference between sources (Figure 1). Body weight gain increased significantly with methionine ad- dition, with similar performance observed for OH-Met and DL- Met. Feed intake increased with the dose of methionine.


Amino acid recommendations Total amino acids recommendations for ducks are poorly doc- umented and only some recommendations are known (Table 2). Researchers have suggested that methionine; along with lysine, threonine and tryptophan are the most limiting amino acids in ducks’ practical diets. However, it appears that threo- nine level used in basal diet was lower than some recommen- dations. In addition, the dietary energy levels of the experi- mental diets were slightly lower than used in previous studies. These slight differences might explain the lack of improvement of FCR for supplemented treatments in com- parison to the basal diet. This observation highlights the need to update amino acids recommendations for ducks.


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