PRODUCTION AND HEART-RATE RESPONSES OF CHICKENS BEAK-TRIMMED AT HATCHOR AT 10 OR 42 DAYS OF AGE

Heart rate was monitored before and after beak trimming in restrained chickens to measure responses to beak trimming at hatch and at 10 and 42 days of age. Immediately after trimming chickens sham-trimmed (cont rol) and trimmed at 10 and 42 days of age had an increase in heart rat e, with the 42-day-old chickens showing the greater change. Chickens s ham-trimmed and trimmed at hatch showed no change in heart rate. No di fference between trimmed and sham-trimmed chickens occurred at any age for heart rate response. These data indicate that heart rate at trimm ing may be inadequate as a measure of the stress response associated w ith beak trimming, especially with the concurrent stressors of handlin g and restraint. Beak trimming and handling of chickens at hatch is ei ther less stressful than trimming at 10 and 42 days of age, as indicat ed by the lack of a heart rate response, or heart rate is already at a maximum in chickens at hatch, due to stress associated with hatching. Food intake and body weight were measured for 3-4 weeks after trimmin g to assess the longer term effects of age and level of trimming on pe rformance of the chicken. Removal of 3 mm of beak at hatch or 4.5 mm a t 10 days of age depressed feeding levels and a reduced body weight, i ndicative of a chronic stress associated with beak trimming.