Management-induced stress and its measurement in poultry

Beak-trimming, floor type, force molting, heat stress, food and water deprivation were studied to determine their stress implication. Pullets raised on litter versus wire were either beak-trimmed or nontrimmed. Adrenals of nontrimmed birds were significantly heavier (0.139 g vs 0.019 g) at the end of the pullet growing cycle, giving evidence that beak trimming reduced chronic stress levels. Hearts and spleens were not significantly affected. The birds grown on litter had heavier (by 13%) adrenals versus wire conditions indicating a stress situation. This is because litter birds had outbreaks of cannibalism in both studies, an indication of a stressful interaction among penmates. Trimming had a short-term effect on feed intake; however, birds soon recovered and consumption equalized between the two groups. Birds grown on litter consumed more feed (6804 g vs 6463 g) than trimmed birds. Pullets from the rearing studies were placed in the laying house and evaluated further. Trimmed layers reared on litter had smaller adrenals (0.0772 g vs 0.1484 g) when the study was terminated. Neither trimming nor rearing floor type had an effect on layer performance. However, birds from wire rearing did not adapt as quickly to cages as litter reared birds. Force molted hens had similar adrenal and heart weights, but larger ($P\u3c$.05) spleens when compared to non-molted hens. Layers were observed in five different adverse (stress) conditions: without feed, without water, heat stressed, without feed but could see the feed (frustration) and beak trimming. Sonograms were made of the vocalizations and compared with birds under normal conditions. Birds under stress produced different vocal calls than birds under normal conditions. The number of calls from birds under stress decreased in quantity and increased in duration compared to normal conditions. There was an increase in the high and low frequencies caused by stress