N. Snapir

Heat stress effects on capillary blood flow and its redistribution in the laying hen

The effect of heat stress on capillary blood flow (CBF) distribution was examined in laying hens, using 15 micron microspheres, by determining CBF before and after elevating body temperature by 1–2°C. No change was evident in unfeathered metatarsal skin, although its temperature increased by 7°C. Breast skin CBF change was 3.5 times larger than that of back skin. Comb CBF increase was larger than in wattles. CBF in upper respiratory tract increased proportionally to increment in respiratory frequency. Digestive system CBF was reduced by hyperthermia: the effect was pronounced in its upper organs (46% of normal) and decreased along the tract. CBF increased 4-fold in an expiratory abdominal muscle, a smaller rise occurred in a pectoral muscle and no change in a leg muscle. CBF in the tibia fell to 64% of normal. In the reproductive system, CBF fell to 58% of control level in the uterus, to 70–80% in the larger ovarian follicles and infundibulum with no significant changes in magnum and isthmus. Cerebral CBF increased during hyperthermia.Heat stress significantly reduced CBF to inner body organs, with marked differences between systems as well as within systems. Changes were more pronounced on 2°C hyperthermia than on 1°C hyperthermia.

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.

Effect of diurnal or nocturnal heat stress on egg formation

1. Mature laying hens were subjected to ambient temperatures sufficient to maintain body temperature of 43 degrees C for periods of 6 to 7 h during the day (eight periods) or the night (five periods). This did not reduce total daily food consumption. 2. The effect of heat stress during the day was mostly on egg-shell quality, being adverse and significant. During the night heat stress caused a significant decrease in egg production, its effect during the day was less marked in this respect. 3. Heat stress thus seems mostly to affect the early stages of shell formation, while its effect on egg production seems to depend on the time at which it occurs in relation to ovulation. 4. These results suggest that egg production is directly affected by heat stress; prolonged heat stress probably also acts indirectly, by suppression of food intake.

The relation of fasting and resting metabolic rates to heat tolerance in the domestic fowl

Synopsis 1. Resting metabolic rate (RMR) and fasting metabolic rate (FMR) were periodically determined, using an open air circuit master system, from January to September in 10 White Leghorn, 10 Plymouth Rock and 20 New Hampshire × White Leghorn mature laying birds fed ad libitum. 2. The relationship of metabolic rate (l.O2/hr.) to body weight (kg.) in the pooled data followed the 0.795 W0.61 equation for the fasting level, and 0.916 W0.59 for the resting level. The expression of metabolic rates as litres oxygen per kg. body weight can lead to serious errors if birds of differing body weights are compared. 3. Heat increments of feeding (estimated by RMR‐FMR) gradually increased with rising environmental temperature, with only slight initial change in the FMR, followed by marked reductions in both the FMR and the RMR at the higher temperatures. It is suggested that a decrease in the FMR may allow for a reduction in the RMR in the hotter season, without this necessarily being linked with a depression in the...

The effect of light wavelength on the production and quality of eggs of the domestic hen

Abstract The effect of light color on egg-laying and on egg quality during the first 50 wk of egg production and during a second cycle of 19 wk following molting was examined. Hens were exposed to one of the following six sources of light: blue (B), green (G), red (R), tungsten (T), cool-white (C) fluorescent or simulated-sunlight (V) fluorescent tubes. Light intensity was equalized at photon output. Total egg production per hen was significantly influenced by the color of light with the most eggs being procuced in R light and the fewest in B light. Hens were more sensitive to light color in response to egg production during the second cycle than during the first cycle. Hens in C light produced significantly fewer eggs than those under V light in both laying cycles. Eggs laid under B or G light were consistently larger than those under R light. Egg weights of hens in V light were heavier than those for the C or T light groups. In the first cycle, shell quality was significantly better in G light than in B or R light. Percent of yolk increased and percent of albumen decreased with age during the first cycle in all treatments and the rate of change was directly related to light color (wavelength). In the second cycle, shell quality, percent of shell, yolk and albumen did not change significantly with age in any of the light treatments. It can be concluded that the wavelength of light may influence egg production, egg components and shell quality of the domestic laying hen.

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.

Method for collecting semen from the ostrich (Struthio camelus) and some of its quantitative and qualitative characteristics

1. Four methods of semen collecting that involved interruption of mating in two breeding ostrich pairs were tested: an artificial vagina was tested without promising results; the funnel method, in which a funnel was placed under the phallus of the tested male immediately after mating allowing semen drips to be collected; the vacuum method, using a turkey semen collector, inserted into the seminal canal; and the tube method, conducted by placing a test tube inside the seminal canal, allowing semen to enter by gravity. 2. For the funnel, vacuum and tube methods, respectively, average semen volume was 0·1 ± 0·02, 1·12 ± 0·22, and 0·58 ± 0·13 ml, sperm concentration was 0·66 ± 0·14, 2·35 ± 0·26, and 2·13 ± 0·27 × 109 cells/ml, and percentage of abnormal cells was 5·82 ± 1·79%, 4·68 ± 1·19%, and 7·09 ± 1·72%. 3. Semen characteristics varied throughout the reproductive season reaching peak concentration in June-July. 4. The vacuum method proved to be the most efficient and was a low stress, restraint-free method for collecting ostrich semen.

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.