Influence of toe-clipping and stocking density on laying hen performance.

Three experiments were conducted to investigate the influence of toe-clipping and bird density on laying hen performance. Toe-clipping was done on day-old chicks by removal of the digital claws from the front toes. Toe-clipped (TC) and intact (IN) pullets were assigned randomly to laying cages (Experiments 1 and 2, 19 weeks of age) or housed in similar body weight groups (Experiment 3, 18 weeks of age) at caging densities of either 4 (465 cm2/hen) or 5 (372 cm2/hen) hens per cage. Experiment 3 body weight groups were: heavy (greater than or equal to 1475 g), medium (greater than or equal to 1375 g, but less than 1475 g), light (greater than or equal to 1275 g, but less than 1375 g), and extra light (less than 1275 g). Body weights were determined at various ages during the grow-out and egg-laying periods. Beginning at 22 weeks of age, average daily egg weight, feed consumption, feed conversion, hen-day egg production, and mortality measures were made for 12 periods of lay of 28 days each. In Experiments 1 and 2, IN pullets were consistently heavier throughout the grow-out period and consumed significantly more feed during the egg laying period than TC birds. Significantly greater average daily egg weights were found in IN than in TC hens in Experiment 1 but not in Experiment 2. Increasing the number of hens from 4 to 5 hens per cage resulted in a significant reduction in feed intake and body weight gain in Experiments 1, 2, and 3. In Experiment 1, mean daily egg weight was significantly increased (.11 g) upon crowding. In Experiment 2, crowding elevated mortality. In Experiments 1 and 2, but not 3, a significant toe treatment by bird density interaction was observed for hen-day egg production. The IN birds had lowered hen-day egg production rates when crowded than when they were afforded more space, whereas hen-day egg production was elevated in crowded TC hens when compared to TC hens housed at the less crowded density. In Experiment 3, an initial (4 weeks of age) significant depression in pullet body weight was found in the TC pullets but disappeared by the 8th week. Feed usage was also significantly greater in IN than in TC hens in Experiment 3. Toe treatment did not affect any other hen performance variable measured. Egg weight, feed intake, and feed conversion measures varied by body weight groups. In general, the heavier hens consumed more feed and laid heavier eggs, but they were less efficient in converting feed into eggs.

In vitro prostaglandin E2 stimulation of 45Ca mobilization from chick bone.

The ability of prostaglandin E2 (PGE2) to mobilize 45Ca from chick embryo long bones was assayed in an in vitro bone culture system. Concentrations of PGE2 tested ranged from 10(-9) to 10(-5) M. The PGE2 was effective in stimulating release of 45Ca from prelabelled bones at all concentrations tested except at 10(-9) M. In addition, stimulation of 45Ca release could be produced daily for 4 consecutive days of PGE2 culture-pulsing at what appeared to be the optimal PGE2 concentration, 10(-7) M. We conclude, as in mammals, PGE2 is a potent stimulator of calcium mobilization from avian bone. The potential involvement of prostaglandins in eggshell formation is discussed.

Circulating corticosterone responses of feed and water deprived broilers and Japanese quail.

Experiments were conducted to delineate the acute stress response of commercial broilers to feed and water deprivation for 10 hr. The effect of method of nutrient deprivation, cooping versus removal of feed and water from broiler floor pens, was also considered. Bihourly plasma corticosterone measures were made during 10-hr withdrawal periods, and significant alterations in this adrenal steroid were considered indicative of stress. In all studies, feed and water deprivation produced significant elevations in plasma corticosterone concentrations. Cooped broilers exhibited a shorter onset and more exaggerated magnitude of adrenal responsiveness than floor penned broilers deprived of feed and water. There was also evidence that plasma corticosterone secretion in floor penned broilers was continual (linearly increasing) throughout the 10-hr withdrawal period. In contrast, maximal corticosterone responses followed by waning hormonal levels (an increasing quadratic function) were evident in cooped broilers. It was concluded that procedures involved in physically cooping birds, as well as the restraint cooping imposed, were acting additively to the stress associated solely with feed and water deprivation. Changes in plasma volume, as evidenced by percent packed cell volume changes during treatment periods, were not responsible for the corticosterone elevations observed. In a separate experiment, battery housed Japanese quail deprived of feed and water for 12 hr exhibited a temporal plasma corticosterone response very similar to that observed in floor penned broilers deprived of feed and water. Full-fed control quail exhibited only random temporal hormonal fluctuations during this time. It was likewise concluded that the practice of feed and water deprivation in quail constitutes a significant nonspecific stressor.

Circulating corticosterone response of wild-type Japanese quail to albino quail intrusion.

Two experiments were conducted to determine the ability of albino Japanese quail intruders to elicit serum corticosterone responses in established populations of wild-type (W-T) quail. In Experiment 1, W-T quail were mixed with albino strangers and blood sampled prior to (T0) and 2 hr after (T2) mixing. A second W-T group, serving as a control, was bled at these same times but was not subjected to albino intrusion. In Experiment 2, a similar protocol was followed, except albino treated and control quail were not bled at T0. Blood samples were assayed for their serum corticosterone content by radioimmunoassay. The incidence of headbanging behavior by W-T quail from T0 to T2 was also determined. Both control and albino treated W-T quail exhibited significantly elevated mean serum corticosterone levels at T2 when compared to their T0 hormone levels. However, when the quail were not bled at T0, a significantly higher mean plasma corticosterone level was found at T2 in albino treated wild types in comparison to control treated quail at this time. Although percent of individuals headbanging was similar in both control and albino treated W-T quail handled at T0, albino quail intrusion produced a significant doubling in the incidence of headbanging by W-T quail not previously handled. Serum corticosterone and headbanging behavior were not correlated. Collectively, these data would appear to indicate that albino quail intruders serve as effective nonspecific systemic stressors to W-T quail, provided the latter are not handled beforehand.