The effects of pre-transport supplementation with electrolytes and betaine on performance, carcass yield and meat quality of broilers in summer and winter

Abstract

Abstract The consequences of high ambient temperature for broiler chickens collectively results in poorer productivity, prostration and even death. As they approach processing weight, broilers are particularly sensitive to heat stress as they produce large amounts of metabolic heat. Transport from farm to the processing site is a stress for broilers. So, the combination of high ambient temperature prior to transport and the stress associated with transport to processing have unwanted effects on broiler performance and meat quality. In two experiments (summer and winter) the effect of supplementing the water of Ross-308 broiler chickens with electrolytes, with or without betaine for 2 days before processing, on performance and breast muscle meat quality were investigated. In the summer experiment broilers were exposed to a cyclic high temperature protocol over the two days (9 h at 28–29 °C and 14 h at 22–24 °C). In the winter experiment the shed temperature ranged between 14 and 18 °C. The growth performance of birds during supplementation and then the breast muscle meat quality 24–72 h post-mortem were determined. In both experiments betaine had no effect on any performance or meat quality measure and the electrolyte supplementation had no effect on growth performance. In the summer experiment, electrolyte supplementation had significant effects on some measures of meat quality. Breast muscle from supplemented birds had lower 24 h post-mortem pH and based on meat ‘lightness’, lower levels of PSE meat. The 72 h drip loss was significantly lower in meat from birds that had been supplemented with electrolytes. The electrolyte supplements had no effects on meat ‘redness’ or ‘yellowness’, on shear force or cooking losses. In the winter experiment, the electrolyte supplementation had no effect on growth performance or breast muscle meat quality. In this experiment, the average shed temperature was approximately 16 °C with peak values of approximately 18 °C. The growth rate of the birds was approximately 40% higher than that identified in industry performance standards for the Ross-308 strain. The data suggest that the temperature for best performance of the Ross-308 is lower than the 18–24 °C currently accepted as ideal. In all experiments there were significant effects of bird gender on performance and meat quality measures. While electrolyte supplementation supported improvements in meat quality during periods of moderately high ambient temperature, the commercial benefit of these would need to be assessed. The value of electrolyte supplementation is likely to be more substantial when broiler chickens experience heat wave conditions with temperatures > 32 °C, but this remains to be evaluated.