ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 95, Number 4
Comparative physiological responses of exotic turkeys (Meleagris gallopavo, Linnaeus, 1758) fed different dietary methionine types under hot humid conditions
A study was designed to determine the physiological response of exotic turkey (Meleagris gallopavo, Linnaeus, 1758) from 29 days to 112 days of age when their diets were supplemented with different dietary methionine types under hot humid conditions. One hundred and ninety six turkeys were allotted to seven treatments comprising four replicates and seven birds per replicate. The birds were offered diets containing 65% CP fishmeal (control diet - CT), dietary DL- Methionine at optimum level (DLM), DL- Methionine at high level (DLH), Methionine hydroxyl analogue at optimum level (MHA), Methionine hydroxyl analogue at high level (MHH), Herbomethionine at optimum level (HMO), and Herbomethionine at high level (HMH). Blood samples were collected at different phases of growth for the determination of the concentration of plasma corticosterone, superoxide dismutase (SOD), Malondialdehyde (MDA), and triiodothyronine (T3). Relative weights of the organs of the birds were also determined. Data obtained were laid out in a 3*2+1 factorial arrangement based on a completely randomized design and analyzed using the linear model procedure of SAS (2008). The results showed that the turkeys in MHA (1.31ng/ml) and MHH (1.54ng/ml) treatment group had reduced (P<0.05) levels of plasma corticosterone compared to DLM (1.87ng/ml), DLH (2.02ng/ml), HMO (2.35ng/ml) and HMH (2.51ng/ml) and CT (2.53ng/ml) treatment group. DLH, MHA and MHH prevented cell damage compared to other treatment groups. Also, birds in MHA (2.02), MHH (0.8) at the pre starter phase and DLM (1.29 micro mol/mL) at the finisher phase had improved MDA (P<0.05). It was concluded that methionine types elicited varying physiological responses in exotic turkeys under hot humid conditions. Overall, MHA gave better results than other methionine types. The results in this study indicate that supplementation of DL-Methionine, at optimum level at the finisher phase, and methionine hydroxyl analogue at optimum and high levels at the pre-starter phase helped to reduce the stress levels. Moreover, the age of turkeys should be considered when selecting the types and levels of methionine to use under hot humid conditions.
Keywords: Methionine types; turkeys; environment; physiology Animal Science; Animal Physiology