Effect of supplemental roughage on behavior, physiological stress response, and egg production parameters of farmed...

The objective of the present experiment was to test the hypothesis that supplemental feeding of roughages (maize silage, rucola salad, or wheat sprouts) would reduce behavioral and physiological signs of stress and increase egg production. A total of 160 adult partridge breeder birds were housed in pairs of 1 male and 1 female/cage during the egg-laying period from April to June. Birds fed on maize silage spent more time laying and less time foraging than birds in the wheat sprout treatment (P < 0.05). Birds fed wheat sprouts were more active than control birds (active 57 vs. 43% of the time, P < 0.05). Birds on the western side of the shed spent more time eating (3.9 vs. 1.24%, P < 0.01). Aggression and dustbathing were rarely seen, and feather pecking was never observed. The basal level of corticosterone (SD) was, on average, 11.4 (6.0) ng/mL of plasma and was not affected by treatments. After 15 min of crating, the average level of corticosterone was 50.0 (20.5) ng/mL of plasma, and strongly tended (P = 0.066) to be higher in the birds on the wheat sprout treatment compared with those on the control or other treatments. Fewer eggs (P < 0.05) were produced by birds on the wheat sprout treatment compared with those on the control treatment (on average, 45.9 vs. 52.1 eggs in total and 40.9 vs. 47.3 eggs for setting). Treatments did not affect egg fertility, egg hatchability, or the number of hatched chicks. In conclusion, we cannot recommend supplementing partridge diets with wheat sprouts during the egg-laying period because this seems to cause behavioral and physiological stress responses and impaired egg production. In general, partridge breeders in the production system investigated here did not show overt signs of maladaptive behavior or physiological stress when fed pelleted concentrate only or concentrate with supplements of maize silage or fresh rucola salad.