B. Robinzon

An enrichment object that reduces aggressiveness and mortality in caged laying hens.

The effect on aggressive pecking activity and mortality by an environmental enrichment device was examined. In this study, 2955 White Leghorn chickens from three different lines were used in six separate experiments. Experiments were conducted with chickens during their first or second laying period. Half the cages in each experiment were equipped with colored key rings or an enrichment object manufactured by Gallus Ltd. (Israel). Experimental and control groups of cages were distributed in an alternate serial order for each experiment which lasted for 3, 4, 5, 8, 9, and 10 months. The enrichment devices significantly reduced aggressive head-pecking behavior and significantly decreased the mortality rate from 1.06% per month among the controls to 0.57% among the experimental groups.

Hyperphagia without obesity in septal-lesioned cocks

Abstract Placement of electrolytic lesions in the septal area (S.A.) in chickens caused a marked increase in food intake which was not accompanied by development of obesity. Oxygen consumption of the S.A. lesioned birds was significantly higher than that of the controls. Alcianophylic-thyrotropic cell population of the adenohypophysis and percentage of active follicles in the thyroid gland were higher for the S.A. lesioned birds than for those of the control birds. The S.A. lesions caused also an increase in the somatotropic activity. The possibility that the previously found suppression effect of the olfactory bulbs on the thyrotropic and somatotropic activities in the intact chicken is mediated via the S.A., is discussed.

Removal of olfactory bulbs in chickens: Consequent changes in food intake and thyroid activity

Surgical removal of the olfactory bulbs (O.B) in the chicken caused a marked increase in food intake, which was not accompanied by development of obestiy. Oxygen consumption of the O.B. removed birds was significantly higher than that of the controls. Alcianophylic-thyrotropic cell population of the adenohypophysis and the percentage of active follicles in the thyroid gland were higher for the O.B. removed birds than for those of the controls. Feed supplementation of 0.1% propylthiouracil to the O.B removed birds abolished the previously exhibited hyperphagia and caused a significant decline in oxygen consumption. The possibility that the O.B removal caused a primary increase in thyrotropic axis activity follwoed by a secondary compensatory hyperphagia, is discussed.

The involvement of gonads and gonadal steroids in the regulation of food intake, body weight and adiposity in the White Leghorn cock ☆

The effects of long-term injections of testosterone propionate (TP), diethylstilbestrol (DES) and TP+DES simultaneously to castrated and sham-operated White Leghorn cocks on feeding, weight gain, obesity, blood lipids and weight of various glands were studied. DES induced marked adiposity while TP reduced carcass fat content. Injections of TP+DES induced only moderate obesity. The responses of the castrated cocks to TP or DES were not always parallel to those of the sham-operated ones. In sham-operated cocks, TP induced permanent hypophagia and emaciation while in castrated cocks, although alleviating adiposity, it did not reduce the rate of weight gain and induced only a transient hypophagia. DES induced permanent hyperphagia and accelerated weight gain in sham-operated cocks while in those castrated, it induced only transient hyperphagia which later on changed into hypophagia. Although the latter cocks did not gain more weight than those castrated with no steroids supplementation, they were much more obese and had a fat content similar to that of the sham-operated ones treated with DES. The castration was found to alleviate the depressing effect of TP on adenohypophyseal and thyroidal weights. The results may suggest: (1) In the White Leghorn cocks, DES increases lipogenesis and food intake while TP results in the contrary. (2) Castration should not be considered as a lack of gonadal steroids only.

Tamoxifen advances puberty in the White Leghorn hen.

1. Tamoxifen (TAM) administration advances puberty in cockerels. In the present study the effect of TAM administration on the sexual development of White Leghorn hens was studied. 2. Two-week-old White Leghorn females were injected intramuscularly with TAM on alternate days at doses of 0.1 mg (0.1 TM), 1 mg (1TM), 5 mg (5TM) and 10 mg/kg body weight (10TM) respectively, while the controls were injected with maize oil (vehicle). The experiment was terminated at 23 weeks of age, when all the control hens laid eggs. Sample autopsies were made on chicks of 6, 14 and 23 weeks of age. 3. Body growth was not affected by any of the treatments. 4. Comb growth was accelerated by all doses of TAM, while hematocrit increased in the 1TM, 5TM and 10TM hens. 5. Egg laying advanced in the 0.1TM and 1TM birds, was delayed in 5TM hens and did not occur at all in the 10TM females. 6. TAM caused a precocious increase in plasma oestrogen and androgen, suppressed adiposity in a dose-related manner and, at low doses, advanced the development of the gonadal system. 7. At 23 weeks of age, when the gonadal system of the controls was fully active, TAM caused a dose-related depression in abdominal fat, liver, ovary, and oviduct weights, plasma total lipids and calcium concentrations and a dose-related increase in plasma oestrogen and androgen titres, and comb weight. 8. It seems that TAM increased gonadotropic activity and its androgen stimulating action, but suppressed peripheral signs of the elevated plasma oestrogen titres. Low doses of TAM enhanced gonadotropic activity and egg laying but the antioestrogenic effect depressed development of the gonadal system, suppressing egg production when high doses were administered. It therefore seems that oestrogens are necessary for normal ovarian development in hens.

The drinking response of the chicken to peripheral and central administration of angiotensin 11

Intravenous injection of Ang II (val5 angiotensin II amide) elicited an immediate drinking response in the domestic fowl which lasted at least 20 minutes. The minimal dosage needed was 300 mug. Intracranial injection of 10 mug Ang II through cannulas implanted in the anterior diencephalon caused a significant increase in water intake. The minimal intracranial dosage of Ang II which evoked drinking was 2.5 mug. Intracranial injection of isotonic KCl inhibited the drinking response induced by intravenously injected Ang II when administered simultaneously. This suggests that drinking caused by both intravenous or intracranial injection of Ang II is activated through identical brain regions. The positive drinking response of the chicken is repeated concecutive intracranial injections of Ang II declined from the first injection through the following ones.

The effects of embryonic treatments with gonadal hormones on sexually dimorphic behavior of chicks

In order to study the role of sex steroids in the differentiation of chick behavior, two groups of experiments were carried out. The first part of the study documented sexual dimorphisms in three behavioral measures in chicks: open-field activity, flocking response, and masculine sexual behavior activated by testosterone (crowing, waltzing, and mating attempts). In the second part, possible organizing influences on these sexually dimorphic behaviors were examined. Male and female embryos were injected with estradiol benzoate (EB) or testosterone propionate (TP). Treatment of males with EB or TP demasculinized all three behaviors. None of the steroid treatments had any effect on the behavior of the females. Plasma testosterone levels of the chicks were not affected by any of these treatments, either before or after testosterone activation. Comb weight was reduced by treatment of male embryos with EB and increased by TP in female embryos, which suggests different mechanism for the development of somatic and behavioral characteristics. The results suggest that exogenous T or E given embryonically can exert similar effects on both sexual behavior and nonreproductive activity of chicks.

Arginine vasotocin and mesotocin in the anterior hypothalamus, neurohypophysis, proventriculus and plasma of white leghorn cockerels, during dehydration

1. The effect of 96 hrs of water deprivation on plasma electrolytes, osmolarity, arginine vasotocin (AVT), mesotocin (MT), and on AVT and MT content in the neurohypophysis, anterior hypothalamic area (AHA) and proventriculus, was studied at 24 hrs intervals, in adult White Leghorn cockerels. 2. Plasma AVT increased three fold during the first 24 hrs but there was no further change during the next 48 hrs. In the last 24 hrs, plasma AVT decreased in about 25%. Plasma MT did not change during the entire period of dehydration. 3. Plasma sodium and osmolarity gradually increased during that time. 4. Neurohypophysial AVT content was depleted by 95% during the period of dehydration while MT content did not change. 5. In the AHA there was no change in AVT levels during dehydration while the levels of MT increased while in the proventriculus there was no change in either AVT or MT levels. 6. For the data collected during the entire experimental period, no correlation was found between plasma osmolarity and plasma AVT, but there was a highly significant negative correlation between plasma osmolarity and neurohypophysial AVT content. 7. It may be suggested that the depletion in AVT content in the neurohypophysis during progressive water deprivation resulted in an insufficient level of AVT in circulation to enable the cockerels to counter the dehydration. This may explain the death of those cockerels which were dehydrated for a further 24 hr period.

Embryonic sex steroids affect mating behavior and plasma LH in adult chickens

Chicken embryos of both sexes were treated with either antiestrogen (tamoxifen = T), antiandrogen (flutamide = F), aromatization inhibitor (ATD = A), estradiol (E), or oil (control = C). Before puberty, some males of each group were castrated. At puberty, birds were tested under the following regimes: castrated males injected daily with testosterone propionate (CAS + TP) or estradiol benzoate (CAS + EB), intact males (M-INT), intact females (F-INT), and females injected daily with TP (F-TP). In the M-INT and CAS + TP males, E treatment suppressed masculine mating behavior. The embryonic treatments with T, F, and A demasculinized only the frequency of copulations. None of the antihormone treatments caused any masculinization of the sexual activity in the F-TP birds. Untreated males had higher plasma LH than females. The embryonic treatment with E reduced (feminized) the LH levels in CAS + EB birds. This effect was less pronounced in M-INT birds. The results suggest that in chickens, estradiol plays a role in the masculinization of copulatory behavior potential in the developing male embryo. High embryonic estradiol reduces the potential for displaying male sexual behavior at puberty. Feminization of LH secretion requires a high level of estradiol in both embryonic and adult life.

An x-ray atlas of the sagittal plane of the chicken diencephalon and its use in the precise localization of brain sites

Abstract An x-ray atlas of the sagittal plane of the chicken diencephalon, which enables a more precise placement of electrolytic lesions, or the implantation of cannulas and electrodes, was constructed. The localization of brain sites is accomplished on the horizontal and vertical planes only; for the lateral plane coordinates, a previously published complementary atlas is required. A high correlation was found between stereotaxic coordinates and the anticipated locations of electrolytic lesions. A procedure is described, which utilizes radiography with two reference points to determine and facilitate the use of specific brain coordinates.