Effect of acute heat exposure on blood flow and its distribution in the unrestrained laying fowl (Gallus domesticus)

1. The effect of heat exposure (air temperature 35–45°C) for 1.5 h on blood flow distribution between the abdominal viscera and the muscles of abdominal wall and hind leg was investigated in unanaesthetised, unrestrained laying fowl.

2. Heat stressed fowl showed a significant hyperthermia (+ 1.3°C), rapid shallow breathing (229 breaths/min) and significant hypocapnia ( ? 8 Torr).

3. Significant increases in absolute blood flow (ml/g per min) were measured in the kidneys, spleen, liver and duodenum during hyperthermia, but there was no change in the absolute blood flow to the reproductive tract or the relative perfusion of the reproductive tract compared with the other tissues sampled.

4. We conclude that in these acute conditions of heat exposure, blood flow to the reproductive tract of the laying fowl is not compromised by any simultaneous thermoregulatory needs.     

Effects of treadmill exercise on the transfer of plasma triglyceride into the ovary of the laying fowl

1. The effects of 90 min continuous treadmill exercise on the plasma-to-ovary transfer of 14C-labelled triglycerides in laying hens were examined. 2. Exercised birds showed a 4-fold increase in plasma free fatty acid concentration, a 15% decrease in plasma glucose concentration and unchanged plasma triglyceride concentration compared with resting controls. The mean plasma-to-ovary triglyceride transfer rate was approximately halved by exercise. 3. The surface area-specific triglyceride transfer rate was greatest for oocytes weighing 0.25-1.5 g and decreased with increasing oocyte size. The lowest rates were in the small (less than 0.25 g) white oocytes. This pattern was largely unaffected by exercise. 4. Factors that might be responsible for the reduction in triglyceride transfer into the oocytes during exercise include hormonal effects on the permeability of the oocyte envelope, increased competition for plasma lipids by the working muscles and reduced blood flow to the ovary, as a result of the release of vasoconstrictors.     

Effect of a change in environmental temperature on heat tolerance in laying fowl

Laying hens when transferred from accommodation at an ambient temperature (Ta) of 30 degrees C to one of 20 degrees C failed to acclimatise to intermittent heat stress (Ta 38 degrees C) commencing one day after the transfer. After 21 d of intermittent exposure to 38 degrees C these hens showed little or no increase in heat tolerance, whereas hens living constantly at either Ta 20 degrees C or 30 degrees C acclimatised normally. The failure to acclimatise was also observed when hens were transferred from Ta 30 degrees C to 5 degrees C but not when transferred from Ta 5 degrees C to 30 degrees C. The failure to acclimatise following transfer from a warm to a cool environment was accompanied by an increase in food intake; if food intake was not allowed to increase the hens acclimatised normally to heat stress.     

Lecithin--cholesterol--acyltransferase activity in the plasma of immature, oestrogenised and laying fowl (Gallus domesticus).

A study was made of the role of the lecithin-cholesterol-acyltransferase (LCAT) enzyme in the changes in the concentrations and fatty acid composition of the plasma cholesteryl esters of the fowl associated with oestrogen treatment and sexual maturity. Although there was a considerable increase in the concentration of free cholesterol in the plasma of oestrogen treated and laying birds, only in the oestrogen treated birds was it associated with an increased rate of cholesterol esterification. In both laying and oestrogen treated birds, changes in the fatty acid composition of the plasma cholesterol esters could be attributed to related changes in the fatty acid specificity of the LCAT enzyme. Evidence is provided to indicate that the cholesterol esters in the plasma of the fowl are synthesised mainly by the plasma LCAT system. The changes in the rates and fatty acid specificity of the LCAT system in the plasma of the fowl associated with sexual maturity or oestrogen treatment are discussed in relation to the extensive alterations shown to occur in the lipoprotein pattern of the plasma.     

Long-term vasoligation in the domestic fowl (Gallus domesticus)

The effects of long-term (14 months) unilateral vasoligation on the tests and their excurrent ducts of the domestic fowl were studied histologically and ultrastructurally. Severe testicular degeneration and epididymal atrophy were observed in the ipsilateral organs while the contralateral control organs were normal. Massive macrophage activity was observed in the epididymal regions and to a lesser extent in some severely degenerated seminiferous tubules. Several granulomata occurred in the epididymal regions and the ducti deferentes, and most were resorbed or were undergoing resorption at the time of examination.     

Acclimatization of the fowl to intermittent acute heat stress

The acclimatization of poultry to a hot, dry climate was assessed by studying changes in rectal temperature (Tr) during regular daily exposure to an ambient temperature of 38 degrees C and 26% RH. Laying hens of two strains, young chicks, growing broilers and broiler breeders were able to acclimatise, in varying degrees, to these conditions. Acclimatization was characterised by a progressive reduction in the rate of increase in Tr over the period of exposure and the ability to survive conditions that initially would have been fatal. Laying hens could acclimatise if prevented from displaying their normal postural responses to heat stress. Acclimatization was accompanied by a decrease in oxygen consumption when measured at either the acclimatization temperature or at a thermoneutral temperature.     

Evaluation of putative appetite suppressants in the domestic fowl (Gallus domesticus)

1. The effectiveness of the appetite suppressants fenflur‐amine, furanone and crotonolactone were evaluated in a series of experiments with adult male layers and growing broilers of both sexes fed on diets with concentrations of up to 1000 mg/kg.

2. Fenfluramine produced a curvilinear decrease in food intake and body weight in adult layers and growing broilers.

3. Inconsistent responses to furanone and crotonolactone were obtained with adult layers and broilers in cages, but a similar decrease in food intake and body weight for both drugs was recorded in male broilers raised in floor pens.

4. The responses to subcutaneous injection of 20 mg/kg of each drug on food intake over 24 h were comparable to those for dietary inclusion. Fenfluramine, however, produced a greater response in male compared with female broilers and induced signs of hyper‐thermia in broilers and layers.

5. Subcutaneous injection of 50 mg crotonolactone/kg was associated with decreases in the food intakes of 4 strains and there was evidence of different responses between lines.

6. It was concluded that none of the drugs used were likely to be suitable for the control of food intake in broiler breeder flocks.     

Further observations on functional deletion of paraocular glands in the fowl (Gallus domesticus)

Methods are described for inoculation of the fowl Harderian gland with sclerosing reagent and for its surgical excision. Though very destructive the former procedure proved the less reliable in achieving the gland's complete functional deletion. Three weeks after surgical removal of the Harderian glands the lachrymal glands of 10-week-old fowls were heavier and contained more immunocompetent cells than the glands of intact and sham operated birds. When adult birds deprived of both paraocular glands were given sheep erythrocytes or Newcastle disease virus by eye drop they developed slightly higher than normal titres of serum antibody but failed to produce lachrymal antibody.     

Effect of administering two prostaglandin synthetase inhibitors (indomethacin and aspirin) on egg production in the domestic fowl (Gallus domesticus)

The injection of 50 mg/kg bodyweight of a prostaglandin synthetase inhibitor (indomethacin) brought about a delayed oviposition time in birds of three breeds of layers, whereas the injection of 5 mg indomethacin had no effect. The daily ingestion of up to 400 mg aspirin or up to 10 mg indomethacin for three weeks, or 750 mg aspirin or 200 mg indomethacin for two weeks had no effect on egg production, oviposition time, egg-shell water conductance, oviducal prostaglandin synthetase activity or bird behaviour. Prostaglandin synthetase activity was demonstrable in both control and treated birds only in the tubular glands of the shell gland. These observations suggest that prostaglandins play a minor role in normal reproductive activity in the female domestic fowl.     

泰和乌骨鸡黑色素细胞形态与分布特征

本研究旨在从组织、细胞水平上观察泰和乌骨鸡皮肤和肌肉组织中黑色素及其细胞的分布和定位,以揭示乌骨鸡黑色性状的细胞学机制。试验对乌骨鸡皮肤和肌肉组织进行取材、固定、石蜡包埋、切片,并采用HE、多巴、硫酸亚铁、多巴-甲苯胺蓝等多种染色方法进行染色和光镜分析。结果:泰和乌骨鸡的皮肤和肌肉组织中均有成熟黑色素细胞和黑色素的分布,表明乌骨鸡黑色素是由分布于此的黑色素细胞产生和沉积;乌骨鸡黑色素细胞形态因定位不同而异,呈圆形、蝌蚪形、星形和细长树突状不等,黑色素细胞树突间常相互连接成网络状或者条带状。试验表明:乌骨鸡黑色素细胞在两种组织中的分布不均匀,在结缔组织中分布较多。     

Changes in the collodiaphyseal angle with growth in the fowl (Gallus domesticus)

The angle formed between the femoral neck and shaft is referred to as the collodiaphyseal angle. In man, the angle decreases during growth and is frequently different in the right and left limbs. This study examines the collodiaphyseal angle in another biped, the growing fowl. Three groups (A, B and C) of growing fowls were examined. The weight difference between birds would alter the forces applied to the growing proximal femur and at the end of the experimental period the birds in group B weighted three times those in group A. Nevertheless, in all three groups the collodiaphyseal angle decreased from 120 degrees to 108 degrees over the growth period. Where there was a difference in collodiaphyseal angle between right and left limbs the angle was more frequently greater in the right. Bodyweight apparently had little effect on the development of collodiaphyseal angle in the fowl, possibly due to the trocharteric/antitrocharteric articulation reducing the stresses applied to the femoral neck.     

Experimental stimulation of eosinophil production in the domestic fowl (Gallus gallus domesticus)

A method has been devised to produce eosinophilia in birds experimentally. Multiple intraperitoneal injections of bovine serum albumin (BSA) produced a greater response than horse serum in young adult fowls, and injections of 2 ml BSA were more effective than injections of 0.2 ml. The highest eosinophilic responses were obtained with injections of BSA together with aluminium hydroxide. Thymectomy had little effect on eosinophil numbers following horse serum injections but irradiation produced a depressed response. Horse serum that had been heated to 56 degrees C for 30 minutes to inactivate complement and to denature proteins, including possible horse IgE, induced an eosinophilic response in 50 per cent of birds compared with only 14 per cent with unheated horse serum. Furthermore, when the former birds were reinjected after a rest period of 13 weeks, the eosinophilic response followed a similar curve as before but a higher proportion of birds responded. Birds aged over two years did not give a good eosinophilic response after horse serum stimulation. There was no consistent correlation between raised IgE levels and eosinophil numbers. Tolerance to horse serum was detected in some birds using a radial immunodiffusion technique. Analyses of blood plasma from birds with eosinophilia showed a significant increase in total amino acids compared with normal birds.     

Effect of long-term heat exposure on peripheral concentrations of heat shock protein 70 (Hsp70) and hormones in laying hens with different genotypes

1. The effect of long-term, moderate heat stress (30 to 32 degrees C) on heat shock protein 70 (Hsp70) concentration in mononuclear blood cells and plasma concentrations of 3,5,3'-triiodothyronine (T3) and corticosterone in laying hens was investigated. 2. Three groups of 48 hens each (Ethopian line [Angete Melata, Na], New Hampshire [NH], F1 cross [Na x NH]) were divided into an experimental group (24 each) and a control group (24 each, ambient temperature 18 to 20 degrees C), respectively. All hens were kept in individual cages up to an age of 68 weeks and performance data were recorded. 3. Blood samples were taken from the wing vein of 12 hens from each group at weeks 22, 38, 51 and 65 (12 hens x 3 lines x 2 treatments). Mononuclear blood cells were isolated and Hsp70 concentrations were determined by Western Blot analysis with a monoclonal anti-Hsp70 antibody. T3 and corticosterone were measured with commercially available ELISA and RIA kits, respectively. 4. The moderate heat stress caused significantly increased Hsp70 levels compared with the control groups in weeks 51 and 65. However, the responses of the lines were not uniform at different ages. 5. In contrast, T3 levels were significantly decreased in stressed birds regardless of line and age. There was no effect of treatment and line on corticosterone levels during the experimental period. 6. Our results indicate that Hsp70 and T3 levels are affected by mild heat stress applied over a long period but are both involved in independent mechanisms of acquisition of thermotolerance. Further investigations are necessary to clarify whether the observed differences in Hsp70 response between the genotypes are indicators for differences in thermotolerance.     

The effects of progesterone on oviposition and ovulation in the domestic fowl (Gallus domesticus)

1. Following an injection of 0.5 or 0.1 mg progesterone/kg between 0 and 6 h after ovulation, oviposition of the resulting egg was delayed by 1 to 11 h and occurred 26 to 31 h after injection, depending on the dose. The injection terminated the laying of a sequence of eggs by causing the next ovulation to occur a day late. The delayed ovulation occurred at the time normally expected for the first ovulation of a sequence and became the first of a new sequence.

2. Following an injection of 0.5 or (H mg progesterone/kg between 6 and 15 h after ovulation, oviposition of the resulting egg was generally delayed by between 15 and 28 h and occurred at the same time of day as the next ovulation, which was delayed as in the first experimental situation. Subsequent ovulations were resynchronised and followed at intervals according to the normal sequence established before the injection.

3. Injection of 0.5, 0.1 or 0.05 mg progesterone/kg between 12 and 9 h before an expected ovulation advanced the oviposition of the egg already in the uterus (shell gland) by about 3 h. The succeeding ovulation was either advanced or blocked.

4. These observations suggest that the pre‐ovulatory surge of progesterone is directly or indirectly involved in the timing of oviposition and ovulation.     

Histochemical identification of tissue eosinophils in the inflammatory response of the fowl (Gallus domesticus)

A staining technique was developed for the differential identification of tissue eosinophil and heterophil leucocytes in the fowl. Pieces of formalin-fixed skin, challenged with dinitrochlorobenzene (DNCB) or citraconic anhydride (CA), were incubated in a substrate suitable for peroxidase prior to embedding in either paraffin wax, glycol methacrylate or Araldite. This results in deep brown staining of the eosinophil granules while those of the heterophils remain unstained. Heterophils and eosinophils were conspicuous at 30 minutes after challenge in the early inflammatory response. By 48 hours the heterophilic response had diminished and eosinophils had almost disappeared. Only mononuclear cells were seen at 72 hours. It is suggested that the eosinophil leucocyte might act as an early modulator of inflammation in delayed-type hypersensitivity responses in the fowl.     

Effect of non-steroidal aromatase inhibitor on blood plasma ovarian steroid and thyroid hormones in laying hen (Gallus domesticus)

HyLine Brown laying hens at 30 weeks of age were treated twice daily with Fadrozole, a non-steroidal aromatase inhibitor (AI; 1 mg/kg body weight; i.m.) for six consecutive days; control hens received saline. Blood was collected every day 0.5 h after oviposition, i.e. just before AI treatment. Ovarian steroids: progesterone (P4), testosterone (T) and estradiol (E2), and iodothyronines: thyroxine (T4), triiodothyronine (T3) and reverse-triiodothyronine (rT3) were measured in blood plasma by radioimmunoassay methods. In AI-treated hens a gradual delay in oviposition time was observed. AI significantly decreased P4 and E2 levels, maximally by 43% on day 4 and by 74% on day 5, respectively, and elevated T level, maximally by 248% on day 4. Simultaneously, the increases in T4 and T3 levels with no changes in rT3 levels were observed. The maximal effect of AI on T4 and T3 levels was found on day 4 (60% increase) and day 5 (312% increase), respectively. Moreover, statistically significant, negative coefficient of correlation between E2 and T3 (r = -0.51), and positive coefficient of correlation between T and T3 (r = 0.42) in AI-treated hens were found. The results obtained indicate that in mature laying hens there is a strong relationship between ovarian steroids and thyroid hormones, and suppression of E2 synthesis not only disrupts ovarian function but also affects the activity of the thyroid gland and peripheral metabolism of thyroid hormones.