Abstract
The objective was to elucidate the effects of chronic heat stress on carcass traits, muscle oxidative stability, muscle fatty acids and amino acid profiles in broiler chickens. A total of 100-day-old male Ross broiler chicks were divided into two equal groups of five replicates. The control group (TN) was maintained on a thermoneutral condition, while the experimental group (HS) was subjected to 8 h of heat stress (34 °C). The HS group showed lower dressing percentage and breast yield compared with the TN group (p = 0.040 and 0.042, respectively). Meanwhile, heat stress significantly increased the percentage of abdominal fat in broiler chickens (p = 0.001). The HS group showed significantly lower levels of PUFA (linoleic, docosahexaenoic and eicosapentaenoic) in the breast (p = 0.003, 0.002 and 0.001, respectively) and thigh (p = 0.001, 0.009 and 0.003, respectively) muscles than did the TN group. The levels of α-lenolinec acid in the breast and thigh muscles did not differ between both experimental groups (p = 0.818 and 0.060, respectively). With exception of threonine, tyrosine and phenylalanine, the levels of essential AA in the breast muscles were significantly (p ˂ 0.05) reduced in the HS group. The HS group showed significantly higher concentration of malondialdehyde (MDA) in the breast muscles (p = 0.032). Meanwhile, the concentration of MDA in the thigh muscles did not differ between both experimental groups (p = 0.149). Furthermore, the HS group showed significantly lower superoxide dismutase and catalase in heart tissues (p = 0.005 and 0.001, respectively). In conclusion, chronic thermal stress deteriorates carcass yield and the oxidative stability of breast muscles, as well as the levels of PUFA and essential AA in broiler chickens. However, the oxidative stability of thigh muscles was not affected.
Highlights
Introduction iationsIn the tropical and subtropical regions, heat stress is the main limiting factor of poultry industries [1]
The effects of chronic heat stress on carcass traits of broiler chickens are illustrated in heat stress increased the percentage of abdominal fat in broiler chickens (p = 0.001)
Chronic heat stress decreased the concentrations of monounsaturated FA (MUFA) in breast (p = 0.005, 0.012 and 0.007, respectively) and thigh (p = 0.003, 0.018 and 0.008, respectively) muscles of broiler chickens
Summary
Introduction iationsIn the tropical and subtropical regions, heat stress is the main limiting factor of poultry industries [1]. The harmful effects of thermal stress to poultry health and production are likely to continue in the future. In this context, broilers are more liable to thermal stress due to their fast growth, rapid metabolic rate and high level of production [3]. As a compensatory mechanism to reduce the burden of heat stress, birds try to decrease the heat production by reducing feed intake and reducing growth rate and profitability [4]. Heat stresses can be classified as acute or chronic depending on the duration and severity [5]. Previous studies suggested that acute thermal stress could reduce the quality attributes of breast muscles in broiler chickens [6].
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