A. van Tienhoven

Dominance rank and cage density effects on performance traits, feeding activity and plasma corticosterone levels of laying hens (Gallus domesticus)

Abstract The effects of dominance rank and cage density on egg production rate, feeding activity, body weight gain, egg weight, shell strength and plasma corticosterone levels were determined for adult laying chickens in battery cages. White Leghorn layers were housed 5, 6 and 7 per cage, which provided 430, 358 and 307 cm 2 of floor area per bird (low-, moderate- and high-density cage environments, respectively). The chickens were maintained on a controlled lighting program of 8L:10D:2L:4D during the production cycle with the 8-h light segment beginning at 08.00 h. Dominance rank and cage density had significant effects on egg production rate and feeding activity. Moderate- and high-density treatments generally resulted in reduced egg production performances and feeding activities. Low dominance rank was associated with reduced egg production rates and feeding activities for the moderate- and high-density environments. However, the relationship of dominance rank with egg production and feeding activity varied with the density. Effects of dominance rank on body weight gain, egg weight, shell strength and plasma corticosterone level were not significant. Blood samples for corticosterone determination were obtained at 49 and 51 weeks of age from 06.00 to 07.00 h and from 19.00 to 20.00 h. Plasma corticosterone levels tended to increase with increasing density, but were not correlated with individual dominance status. Plasma corticosterone analysis failed to indicate a physiological stress response even though individual egg production rates demonstrated reduced well-being for low-ranking individuals. The results show that individual egg production rates may be used as an indicator of well-being for chickens in different cage environments.

Evidence for a positive feedback interaction between progesterone and luteinizing hormone in the induction of ovulation in the hen, Gallus domesticus

Two experiments were conducted to test the hypothesis that progesterone (P4) acts to induce a preovulatory rise of luteinizing hormone (LH) by initiating a true positive feedback interaction between P4 and LH. In each experiment, ten hens were stereotaxically implanted with a third ventricle cannula. Aminoglutethimide phosphate (AGP), an inhibitor of steroidogenesis, was administered (200 mg iv) to hens at 10 and 6 hr (Experiment 1) and 10 and 7 hr (Experiment 2) before an expected C1 ovulation. A 20-micrograms injection of P4 (n = 5) or the vehicle (n = 5) was made intraventricularly at 6 hr (Experiment 1) or 7 hr (Experiment 2) before the expected ovulation. Blood samples were taken via branchial vein cannula at regular intervals after the injection. In Experiment 1, four of five P4-treated hens ovulated, and no atretic follicles were found in any of the five P4-treated hens, including the one which did not ovulate. Ovulations were always accompanied by preovulatory LH peaks. By comparison, none of the vehicle-injected animals ovulated and in four of five hens the largest follicle was determined to be atretic. No ovulations occurred in Experiment 2 for either the P4- or vehicle-injected hens. Atresia of the largest follicle occurred in all five hens in the P4-treated group and four of five hens of the vehicle-treated group. The difference in results between Experiment 1 and Experiment 2 can be explained assuming that the steroidogenesis-inhibiting action of the initial AGP injection in Experiment 1 (at 10 hr before ovulation) had diminished prior to the second AGP treatment (at 6 h before ovulation).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of visual and vocal stimuli on breeding in the budgerigar (Melopsitacus undulatus)

Abstract Under conditions in which food, water and a nest box were provided to caged pairs of Budgerigars, vocalizations from other pairs stimulated male and female gonad development. Under these conditions the presence of four mirrors in a cage had an inhibitory effect on the rate of development of the ovary but not of the testis.

Plasma concentrations of corticosterone relative to photoperiod, oviposition, and ovulation in the domestic hen

Abstract Blood samples were drawn from laying hens via a brachial vein cannula at 2-hr intervals for 34 to 72 hr, and plasma was assayed for corticosterone (B). Concentrations of B, relative to photoperiod and irrespective of the time during the laying sequence, were highest 4 hr after the onset of the photoperiod, and had decreased to lowest values 4 hr before the onset of darkness (photoperiod 14L:10D). There was a surge of B coincident with the time of oviposition. The elimination of the oviposition-related peak of B (by examining concentrations during the morning of the first ovulation in the sequence) shows that the diurnal peak of B actually occurs approximately 2 hr after the onset of light, and that there is no surge of B 4 to 8 hr preceding ovulation as occurs for progesterone, the estrogens, and testosterone.

Relationship between production factors and dominance in White Leghorn hens in a study on social rank and cage design

Abstract The effects of social rank and cage shape on feeding frequency, weight gain, production rate, egg size, shell strength and overt aggressive activity were determined for White Leghorn layers housed six per cage in deep and shallow cages. Social rank significantly affected feeding frequency, production rate, egg size, and aggressive activity for birds in both cage designs. Birds ranking high in the social order fed more frequently, had higher production rates, larger eggs and delivered more aggressive head pecks than birds low in the peck order. The effect for production rate was manifested only at the sixth bird level. Significant social rank effects on weight gain, final body weight and shell strength were not observed. Birds in shallow cages fed more frequently, gained more weight and were involved in more aggressive acts with cage mates than those in deep cages.

Effects of feathers on instrumental thermoregulatory behavior in chickens

Abstract Experiments with domestic fowl confirm that normally feathered chickens utilize species-specific behavior and autonomic responses to cold (at least to−5°C) rather than initiate an instrumental response. When the thermally insulative feathers are removed chickens readily utilize the instrumental response and are able to maintain physiological temperatures not significantly different from feathered birds. Simultaneous measurements of the mean radiant temperature of the chamber and body, skin, and hypothalamic temperatures suggested an approximately equal influence of these three temperatures in the determination of chamber mean radiant temperature.

The effects of exposure to darkness on the reproductive and hypothalamo-hypophysial systems of Budgerigars, Melopsittacus undulatus

Exposure to continuous darkness caused an increase in ovarian and oviduct weight of paired Budgerigar females. The effects of dehydration by salt injection and exposure to continuous darkness on the reproductive system and on the histology of the median eminence, the nucleus supraopticus (NSO), and the nucleus paraventricularis (NPV) was subsequently investigated. Saline injections caused depletion of neurosecretory material (NSM) from the female neurohypophyses (males not investigated), and caused changes in the histology of the hypothalamic nuclei. Salt injections caused smaller body weights, and regression of testes and ovaries. In one experiment, exposure to continuous darkness caused an increase in ovarian and oviducal weights and at the same time caused a decrease in the volume of the cell nuclei of the NPV of males and females, with an accompanying decrease of finely granular NSM in the median eminence. The testicular size was not affected by the light treatment. In another experiments, exposure to continuous darkness did not affect the reproductive system, the histology of the median eminence or of the NSO. The increase in acid phosphatase activity was less in Budgerigars kept in darkness than it was in birds kept under 14 hours of light per day. The acid phosphatase activity in the median eminence of males was higher than that of females.

The effect of ketamine on heart rate, respiration rate and EEG of white leghorn hens.

Abstract 1. Intramuscular injection of 30, 60, 90 or 120 mg/kg of ketamine in adult chickens caused Stage 2 anesthesia. 2. The dose did not affect the depth of anesthesia. 3. The drug caused the appearance of synchronous 4–8 Hz superimposed on 0.5–2.0 Hz activity in EEG recordings from the cerebrum and 14–36 Hz activity superimposed on 4–8 Hz and 0.5–2.0 Hz activity in recordings from the optic lobe. 4. Ketamine did not affect respiration rate significantly, but caused a decrease in heart rate. In this respect the effect was different than that observed in mammals.

Education and the Population Explosion

To determine the extent of knowledge about the population explosion among a highly educated group 1064 undergraduates graduate students and faculty members of Cornell University were surveyed in November 1969 on desired family size knowledge of family planning methods and awareness of population problems. Analysis of the responses to questions on family size desires revealed that 35% of the respondents desired 2 or fewer children 39% desired 3 and 26% desired more than 3 children. It was found that biology grad students have a significantly lesser desire for 3 or more children than other grad students and married students have a lesser desire than unmarried students (both p greater than .05). Oral contraceptives were found to be favored by the respondents for spacing and limiting their families with the intrauterine device and diaphragm the next most frequent choices. Sterilization was found to be highly undesirable and widespread ignorance and misunderstanding was found regarding the consequences of these procedures. Concern over future population growth is aggravated by finding that in a supposedly aware sample 65% desired 3 or more children and that there is an apparent lack of education on specific aspects of contraception and particularly sterilization.

Effects of Progesterone on Uptake and Retention of 3H-Testosterone in the Neonatal Female Rat

Radioactivity concentrations in digested skeletal muscle and extracts of the cerebral cortex and hypothalamus were determined at 15, 30, 60, 90, 120, 150, 180, 210, 240, 270 and 300 min, following inj