Effect of different dietary levels of DL-methionine and the calcium salt of DL-2-hydroxy-4-[methyl] butanoic acid on the growth performance, carcass yield and meat quality of broiler chickens

The present study investigated the effect of different dietary levels of DL-methionine (DLM) and MHA-Ca on broiler chicken performance, carcass characteristics and meat quality. A total of 891 day-old male Ross 308 chickens were allocated to nine groups with 11 replicates each, and were fed on diets supplemented with four levels of dietary methionine (0.04, 0.08, 0.16, 0.24%) and two different methionine sources (DLM and MHA-Ca). The negative control (NC) diet did not contain any supplemental methionine. Dietary treatments had a significant effect on the average daily gain (ADG) and final body weight (FBW) of birds (P=0.001), which were significantly higher in groups given high doses of DLM. Feed conversion ratio (FCR) improved significantly with increasing methionine levels (P=0.001). Methionine addition at 0.24% contributed to a significant (P=0.001) increase in body weight and carcass weight, compared to lower dietary methionine levels. A higher breast muscle yield (P=0.004) was noted in chickens that received diets supplemented with higher amino acid levels. The source of dietary methionine had no effect on carcass characteristics, however, an interaction between the experimental factors showed that birds fed on 0.08% MHA-Ca were characterised by the lowest body weight before slaughter (BWBS), cold carcass weight (CCW) (P=0.001) and breast muscle yield (P=0.026). Dietary methionine levels had no significant effect on breast muscle quality, whereas the breast muscles of chickens fed on diets supplemented with DLM had lower pH(u) compared to those fed on MHA-Ca diets (P=0.021). In conclusion, increasing inclusion levels of methionine improved the growth performance and breast muscle yield of broiler chickens, but they had no influence on meat quality. DLM was found to be a more effective amino acid source than MHA-Ca, and it contributed to higher production efficiency without compromising carcass yield or breast muscle quality.