Water balance of Colostomised and non‐Colostomised hens at different ambient temperatures

1. The quantities of water gained and lost, and hence the total water balance, were determined in normal and colostomised White Leghorn laying hens at ambient temperatures of 5, 20 and 35 °G.

2. In both groups the water intake and water loss at all temperatures were well balanced.

3. Water to food ratios and water content of excreta of normal hens increased with increasing temperature.

4. The wetter excreta at 35 °C are caused by an increased urine production and not by an increased water passage through the alimentary tract.     

Effect of gradual acclimation to temperatures up to 44 °C on productive performance of the desert Bedouin fowl,the commercial White Leghorn and the two reciprocal crossbreds

1. The effect of daily exposures to increasing ambient temperatures (for 7 months) on egg production was evaluated in the desert Bedouin fowl of Sinai, a commercial White Leghorn and the two reciprocal cross breds.

2. High ambient temperatures did not adversely affect egg weight, laying rate or output per bird (g egg per day per g body weight) of the acclimated hens.

3. Best productivity was attained during periods of exposure to 38 to 40° C in all breeds.

4. Rates of decrease from maximal productivity to productivity at 42 and 44 °G differed with breed. Productivity of Leghorn and Leghorn x Sinai crossbred decreased curvilinearly above 40 °C, while productivity of Sinai and Sinai ( Leghorn crossbred decreased at 42 °C and then stabilised.

5. When changes in egg weight and laying rate were examined on an individual basis (comparison between successive months), the differences between Sinai and the Leghorn were more pronounced.

6. The results support previous findings that the Sinai breed and its crosses are able to withstand extreme environmental temperatures, reflecting genetic adaptation to desert conditions.     

The daily food consumption of laying hens in relation to egg formation

The voluntary food consumption of, respectively, 4 and 5 colostomised laying hens was studied in 2 experiments at both normal (20° C.) and high (30° C.) environmental temperatures over a total period of 60 days. Food consumption was greater during 24 hr periods when egg formation was in progress than when no egg was present in the oviduct. At high temperatures food intake was reduced less on egg‐forming than on non‐egg‐forming days.

In a further experiment lasting 24 days 12 normal pullets laying for long sequences with pauses of single days consumed 25 per cent more food in the 19 hr period 14.30–09.30 hr when eggs were being formed than when they were not. During the 5 hr period 09.30–14.30 hr food consumption was significantly greater when albumen was being secreted than when shell formation was in progress.

It is suggested that the requirements of the bird for albumen synthesis may regulate food intake during the period of egg formation.     

Increasing the environmental temperature later in lay and performance of the fowl

1. For laying fowls fed on a conventional diet increasing the environmental temperature from 21 to 27 °C at 333 d of age resulted in a depressed rate of egg output (333 to 500 d).

2. Egg output for birds kept at 27 °C from 333 d could not be increased to the maximum rate of output of birds at 21 °C for this period by feeding a diet of equal energy content containing increased proportions of protein‐rich ingredients.

3. The difference in both food intake and egg output between hens maintained at 21 and those maintained at 27 °C appeared to decrease when the higher temperature was introduced at 416 d of age.     

Influence of temperature during growth on responses of hens to high or low temperatures during lay

1. Commercial pullets were grown at cool (10°‐20°C) or hot (25°‐35°C) temperatures to similar bodyweights at 18 weeks of age. Between 18 and 50 weeks the birds were either kept at the same temperatures as during growth or transferred to the alternate temperature.

2. Birds kept at the cool temperatures throughout life ate most food and gave the best production during lay. Minimum food intake and poorest performance were obtained with birds kept at the hot temperatures throughout life.

3. Performance in the hot environment during lay was improved by rearing birds in the cool environment, the response being related to an increased food intake. Food intake in the cool environment during lay was reduced, with only minor effects on performance, in birds which had been reared in the hot environment.

4. The results of the present study show that production responses during lay are affected by the temperatures experienced by hens during both growth and lay.     

Effects of an induced pause in egg production and supplementation of the diet with iron on egg shell colour,quality and performance of brown egg layers

1. A pause in egg production was induced in brown‐egg laying hens, aged 68 weeks, by feeding them whole oats for 7 d. Subsequently, these hens, together with control groups, were given laying diets with either 400 or 600 mg/kg iron. The 200 mg/kg of supplemental iron was added in the form of either ferrous sulphate or iron proteinate (chelated iron).

2. The feeding of whole oats halted egg production in 5.7 ±0.22 d and the duration of the pause was 8.3 ±0.78 d.

3. The induction of a pause improved the subsequent rate of egg production, egg output, efficiency of food utilisation, albumen quality, egg specific gravity and shell colour. It also increased food intake and body weight gain but neither egg weight nor the rate of mortality were affected.

4. Neither supplementation of the diet with iron nor its source had any significant effect on laying performance, egg quality or shell colour.     

Effect of dietary inclusion of ascorbic acid and palm oil on the performance of laying hens in a hot tropical environment

1. Two experiments were conducted to evaluate the effects of including ascorbic acid (AA), palm oil or a combination of both in the diets of laying hens during the hot months in a tropical environment.

2. The inclusion of AA improved egg production, food intake and efficiency of utilisation, and decreased the cost of food per kg egg. The addition of 400 mg AA/kg diet gave the most efficient performance.

3. Palm oil inclusion reduced the effect of heat stress and increased egg production, egg weight, food intake and efficiency of utilisation.

4. When 200 mg AA and 50 g palm oil/kg were used, additive responses were obtained with further improvements in egg production, food cost and efficiency.

5. Ascorbic acid and palm oil when fed alone or in combination reduced the incidence of cracked eggs.

6. Thus, 400 mg ascorbic acid/kg of diet, 50 g palm oil or 200 mg AA plus 50 g palm oil/kg diet ameliorated the effects of heat stress in laying hens.     

Effect of warm drinking water on the performance and immunological responses of broiler breeder hens raised at low air temperatures

1. The effect of warmed drinking water on the performance and immunological responses of broiler breeder hens maintained at low air temperatures (5.0° to 12.9°C) was tested. From 22 weeks of age hens (mean body mass = 2.4 kg) were offered either warm water (27.7°C; WARM; n=24) or tap water (12.7°C; CONR; n=24) twice daily for a total time of 2.5 h or tap water ad libitum (CONA; n = 16). Food was restricted for all hens.

2. Daily water intake in the WARM hens (103 ml/kg) was similar to that of the CONR (93 ml/kg) and CONA hens (106 ml/kg).

3. There were no significant differences in either body mass change or egg production among treatment groups.

4. There was no difference among groups in heterophil/lymphocyte ratios. Similarly, there was no difference among groups in either phagocytic activity or wattle index after phytohaemagglutinin (PHA) injection. Total and IgG antibody titres to SRBC tended to be highest in the WARM hens and these titres were significantly higher than in CONR hens 14 d after challenge.     

The nutritional value of broad beans for laying hens

1. Three trials were conducted to study the influence of diets containing between 40 and 550 g broad bean (Vicia faba, Major) meal/kg on performance, egg quality and pancreas characteristics of White Leghorn hens.

2. The effect of broad beans on performance depended on the dietary content. Up to 100 g/kg did not affect productivity. Contents higher than 200 g/kg depressed egg weight (P<0.05). At 550 g/kg, food intake, egg weight and rate of egg production decreased but efficiency of food conversion was not impaired.

3. At 550 g/kg broad beans caused an increase in albumen density (P < 0.01). Broad beans did not affect shell thickness.

4. The size, weight, moisture content and histology of the pancreas were not affected by broad bean intake.     

Relationship of plasma calcium and phosphorus to the shell quality of laying hens receiving saline drinking water

1. From 36 to 43 weeks of age 210 White Leghorn laying hens were used to study the relationship of plasma calcium and phosphorus concentrations to egg‐shell quality when saline drinking water was given.

2. Seven experimental treatments in which different amounts of sodium chloride were supplied by the food and/or the drinking water were compared.

3. Increasing salt intake through the drinking water or the food reduced shell thickness and shell calcium, and increased the numbers of damaged eggs. Sodium chloride given in the drinking water was more effective in reducing shell quality and increasing plasma calcium and phosphorus than sodium chloride given in the food.     

Effect of hesperidin dietary supplementation on hen performance,egg quality and yolk oxidative stability

1. The purpose of this study was to evaluate the effects of dietary supplementation with hesperidin (one or 3 g/kg of feed) for 31 d on the performance, egg quality and yolk oxidative stability of brown and white laying hens (26-wk old).

2. Supplementation with hesperidin did not affect egg production, egg weight and egg quality traits.

3. No hesperidin effect on yolk and plasma cholesterol was observed. A strain effect was found with lower total and per g yolk cholesterol of brown hens in comparison to the white ones.

4. Oxidative stability of egg yolk, expressed as ng MDA/g yolk, was significantly improved in the hesperidin groups even from the first week of supplementation. At the same time, a significant improvement in the oxidative stability of egg yolk due to the incorporation of hesperidin in hens’ diet was observed after 30 and 90 d of storage at 20°C and 4°C, respectively.

5. No hesperidin by strain interaction was detected for any of the traits measured.

6. In conclusion, incorporation of hesperidin to laying hens’ feed did not affect productive and egg qualitative traits. On the other hand, dietary hesperidin supplementation significantly improved oxidative stability of both fresh and stored eggs. Antioxidant properties of hesperidin seem to make it a promising natural agent for improving the shelf life of eggs.     

Effect of restricted cooled drinking water on the performance of broiler breeder hens in a hot,dry climate

1. We tested the effect of cooled drinking water on the performance of broiler breeder hens maintained in a hot, dry climate. Hens from 24 weeks of age (mean body mass = 2.5 kg) were offered one of three treatments: cooled water (18.5°C, COLD) or tap water (27.5°C, CONR) twice a day for a total time of 2–5 h, or tap water ad libitum (CONA). Food was restricted for all hens.

2. Daily water influx in the COLD hens (120 ml/kg) was similar to that of the CONR hens (123 ml/kg), but was 36% lower than that of the CONA hens (163 ml/kg). The same pattern was found in the ratio of water drunk (ml/d) to food intake (g/d): 1.85 and 1.88 in the COLD and CONR hens, respectively, and 2.73 in the CONA hens.

3. There were no significant differences in body mass change among groups. Over the first 28 d of treatment, the COLD hens increased their body mass by 20.9 g/d, the CONR hens by 19.6 g/d and the CONA hens by 21.8 g/d.

4. When offered cooled water from 24 to 30 weeks, egg production decreased in the COLD hens. Egg production in this group was similar to controls during weeks 31 and 32, 1 to 2 weeks after treatment had stopped and at a time that all hens were receiving tap water ad libitum.     

The influence of graded levels of atmospheric ammonia on chickens. I. Effects on respiration and on the performance of broilers and replacement growing stock

Experiments have been carried out to study the influence of high concentrations of ammonia on the performance of chickens. One hundred parts per million by volume of ammonia caused reductions in the respiration rate of adult hens of between 7 and 24 per cent. Carbon dioxide production and respiratory depth were also reduced.

Broiler chickens reared in atmospheres containing high concentrations of ammonia from 28 days of age tended to eat less food than broilers reared in ammonia‐free atmospheres and at 100 p.p.m. of ammonia their growth rate was significantly reduced.

Replacement laying pullets reared in atmospheres containing ammonia from 11 to 18 weeks of age, ate less food than similar birds reared in ammonia‐free atmospheres. When the ammonia level was 78 p.p.m. by volume, food consumption was significantly reduced in the period from 15 to 30 weeks of age. This lowered food intake was associated with significantly less live‐weight gain up to 22 weeks of age, and pullets reared in atmospheres with high ammonia concentrations matured up to 2 weeks later than pullets reared in ammonia‐free atmospheres.     

Food,calcium and water intakes by hens lit continuously from hatching

1. Five individually caged Leghorn hens, reared from hatching under continuous light and having their ovipositions uniformly scattered throughout the 24‐h period, were used to study voluntary intakes of a diet low in calcium, oyster shell and water.

2. Food intake was high just after ovulation, decreased during the first 16 h of egg formation, rose transiently 20 to 22 h after ovulation and was minimal just before oviposition.

3. Oyster shell intake was characterised by three peaks, two coincided with those of food diet but the third, occurring between 8 and 12 h after previous oviposition, could be related to the immediate calcium need of shell formation.

4. Water intake followed a similar pattern to food intake but there was an independent rise during albumen plumping (6 to 8 h after previous oviposition).     

Effects of short intermittent lighting on food consumption and performance of dwarf broiler breeders and progeny

1. Two hundred and sixty four dwarf broiler breeder hens were subjected to ad libitum or restricted feeding and to four lighting patterns: 15L (bright light):9D (dark), 15L:9d (dim light), 2L:10d: 1L:11d, (0.5L:3.5d) × 6.

2. Breeder hens fed ad libitum and subjected to either conventional or intermittent lighting ingested respectively, 25 g and 14 to 17 g more than hens restricted to 115 g/d.

3. Body weight was greater in hens fed ad libitum irrespective of the lighting pattern and of the amount of food intake.

4. Persistency of egg production was impaired by intermittent lighting.

5. Ad libitum feeding reduced egg fertility. The decrease was larger in breeder hens on intermittent lighting.

6. Hatchability was increased in hens submitted to the symmetrical lighting pattern (0.5L:3.5d).

7. Egg and chick weights were higher in hens fed ad libitum.

8. Shell index and shell breaking strength increased in restricted hens on the intermittent lighting pattern (0.5L:3.5d) × 6.

9. The best performance was obtained in restricted hens on the conventional lighting pattern.     

Raised environmental temperature and food rationing as means of restricting growth of the replacement pullet

1. Four rearing temperature regimes (15, 20, 25, 30 °C) and three feeding schedules (ad libitum, restricting to the ad libitum intake of the 12th week and feeding 70% of this rate) were carried out with layer replacement pullets to 170 d of age. From this age, during lay, birds were kept at either 21 °C or on a 24‐h cycle of 21 for 18 h and 28 °C for the 6 h before lights out. Both a white and a brown egg‐laying strain were used.

2. Body weight at 169 d of age varied from, on average, 1409 g (15 °C, ad libitum) to 943 g (30 °C, 70% schedule) for the white strain and 1947 to 1250 g for the same treatments respectively for the brown strain. Sexual maturity was considerably delayed by the 70% feeding schedule, only slightly by rearing at 30 °C.

3. Rearing at 30 °C tended to depress subsequent egg output. The 70% feeding schedule at least maintained egg output compared with birds fed ad libitum in rearing.

4. There was a highly significant effect of temperature treatment during lay on food intake. The reduction in food intake due to the 21–28 °C cycle, however, appeared small.     

Effects of environmental temperature and heat production due to food intake on abdominal temperature,shank skin temperature and respiration rate of broilers

1. Eight broilers were used to determine the effects of environmental temperature and the increased heat production attributable to food intake on thermoregulatory physiological responses. Heat production, abdominal temperature, shank skin temperature and respiration rate were measured.

2. Heat production rose with increase in food intake and environmental temperature. Abdominal temperature, shank skin temperature and respiration rate also increased but, at 36°C, there was no difference in respiration rate between the different rates of food intake after exposure for 1 h. Also, heat production decreased with exposure time when the birds were exposed to 28°C and 32°C, but increased at 36°C ambient temperature.

3. Although the effect of the increased heat production on thermoregulatory physiological responses was not greater than that of environmental temperature, the increase in heat production enhanced the effect of ambient temperature on thermoregulatory physiological responses. However, with increasing heat production, the greatest response in shank skin temperature was at 28°C, in respiration rate at 32°C and in abdominal temperature at 36°C.

4. These results suggest that, at high environmental temperatures, arranging feeding management to restrict the increase in heat production may alleviate the effect of environmental temperature.     

Effect of laying on food and water intake in dwarf and normal hens

1. Irrespective of whether the hen carried the dwarfing gene, dw, food intake on days when there was ovulation and oviposition was higher than on days when there was only oviposition.

2. The “ overconsumption “ in dw hens was greater than in the Dw hens.

3. Food intake and shell thickness were correlated, the relationship being particularly close in dw hens.

4. There was a consistent and positive correlation between food intake and weight of egg laid on the same day in both Dw and dw hens.     

Effect of inclusion of sugar beet pulp,pelleting and season on laying hen performance

1. The effect of three metabolisable energy (ME) concentrations 12.2, 11.3 and 10.5 MJ ME/kg and two forms of diet (mash and pellet) on egg production in summer and winter were studied. The different ME values were obtained by diluting the 12.2 MJ ME/kg diet with sugar beet pulp of 2.88 MJ/kg DM. In a 3rd summer experiment the water intake of hens on these diets was examined. Data were analysed by factorial analysis of variance, and the relationship between performance and dietary energy concentration was examined by regression analysis.

2. The use of low energy diets (10.5 to 11.3 MJ ME/kg) decreased egg production in both seasons, but pelleting diets improved egg production and egg weight in summer. Egg weight was not affected by energy density in winter, but decreased in the summer when energy density increased.

3. In winter, food consumption was not affected by the dietary ME, while in summer food consumption increased when the dietary ME increased. Therefore, energy intake was not the same at all energy densities, but tended to increase as the energy density increased.

4. In summer, pelleting improved food efficiency and egg production and increased water consumption and the ratio of water to food intake. Water intake and water: food ratio decreased with increasing dietary energy concentration.     

Association of polymorphism in the prolactin promoter and egg quality traits in laying hens

1. Single strand conformation polymorphism analysis and DNA sequencing was performed in White Leghorn hens to explore the polymorphisms present in the promoter of the prolactin gene. The effects of different genotypes on egg production and quality traits were determined, and expression of the prolactin gene in different genotypes was quantified by real time-PCR.

2. Five genotypes and four alleles at each of two Fragments of the promoter were found, of which the FG genotype in Fragment 1 and the PQ genotype in Fragment 2 were the most predominant genotypes.

3. The genotypes of Fragment 1 had significant effects (P?

4. Prolactin expression in the genotypes of Fragment 1 differed significantly and GH genotyped birds had the highest level of expression. The genotypes of Fragment 2 did not show any significant differences of expression.

5. It was concluded that the prolactin gene promoter was highly polymorphic, and had significant effects on egg quality traits in White Leghorn hens.