Adaptation and Mitigation Strategies in Poultry to Thermal Stress
Supplementation of methionine isomers (DL methionine, MHA Ca and L methionine) in commercial broiler chicken maintained on floor pens (6.6 x 4 feet) containing 22 commercial broilers in each pen during tropical summer (max temp 34.70C+1.07; min temp 26.30C+1.16; max humidity 69.0%+4.82; min humidity 33.6+6.01%) improved the body weight gain, feed efficiency and breast weight of the birds.
Increase was more in DL methionine group followed by L methionine and MHA in that order. Antioxidant variables were not affected by methionine source in diet. Antibody titre against ND vaccine was significantly higher in DL methionine groups followed by MHA and L methionine in that order.
Supplementation of oreganol (250 g/kg diet) replacing antibiotic growth promoter had no effect on body weight gain and feed efficiency. However, lipid peroxidation was reduced while GPRx and FRAP increased significantly with oregano supplementation both in Vanaraja birds and broiler chicken. Similarly, supplementation of MOS (1, 1.5, 2, 2.5 and 3 g/kg diet) up to week 3 had no effect on performance and immune responses of Vanaraja. GSHPx and GSHRx were significantly higher in sera of birds fed 1.5 and 1 g MOS/kg diet, respectively compared to those fed the antibiotic growth promoter.
Studies conducted on commercial broilers in environmental controlled poultry houses indicated that cold stress (26 vs 34°C) reduced body weight gain by 278 g (3.9%) and feed efficiency by 0.06 (3.1%) in birds at the marketing age irrespective of energy and digestible amino acids levels in the feed.
The poor performance of body weight was observed as early as 14th day of age. Similarly, under heat stress (36 vs 26°C) condition, the body weight gain decreased by 484 g (22.9%) and feed efficiency by 0.07 (4.1%).