Use of water electrolyte supplementation for three days prior to processing helps alleviate the consequences of a severe thermal challenge on performance in meat chickens

The effects of supplying water with an 'in-house' or commercial electrolyte formulation for 3 d during severe heat stress on performance and meat quality of meat chickens was investigated. At day 35 of age, Cobb-500 meat chickens (N = 22,11 of each sex/treatment) were allocated to 36 floor pens (12 pens/ treatment). The three treatments were, 1: (Control) tap water; 2: 'In-house' electrolytes at 416.4 g/100 L water; 3: commercial electrolyte(-)at 200 g/100 L water. The treatments were applied from 16:00 h on d 39 to 17:00 h on d 42 of age. On d 40-42 the ambient temperature remained at 20-22 degrees C (17:00-08:00 h), then gradually over 08:00-12:00 h increased to a maximum of 32 degrees C where it remained until 15:00 h, and then reduced to 20-22 degrees C at 17:00 h. The severity of heat stress was assessed using the following Thermal-Humidity Index (THI): THI (%) = 0.8T(db) + RH (Tdb-14.3)/100 + 46.3. At 18:30 h on d 42 birds were loaded and transported to the processing plant and held in lairage overnight. Individual body weights, pen feed and water intakes were recorded at the start and end of the supplementations. In the morning, at the processing plant birds were weighed before and after evisceration with carcasses then stored overnight at 2 degrees C and the following morning breast muscle meat quality traits were determined. Based on the THI values, at peak temperature, birds suffered 'severe thermal discomfort'. Liveweight was improved in both sexes treated with the 'in-house' electrolyte but only males benefited on the commercial electrolyte. The 'in-house' electrolyte improved feed efficiency. There were no effects on losses during transport and lairage or breast muscle yield and meat quality. Behavioural observations indicated that birds spent 74-81 percent of their time crouching on the litter. Temperature beneath crouching birds was on average 4.4 degrees C higher than the ambient temperature and could be adding to the thermal challenge experienced by the birds and warrants further investigation. When supplied during periods of high temperature, electrolyte water supplementation alleviates in part the performance losses.