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.     

Effect of feeding regimen and lighting pattern on the performance of broiler chickens in the hot,humid tropics

1. A food restriction study in conjunction with light control was conducted with commercial broiler chicks in a tropical environment.

2. Chicks on treatments 1 and 2 were fed continuously while those on treatments 3 and 4 were fed during the day (from 06.00 h to 18.00 h) and night (from 18.00 h to 06.00 h) respectively. Chicks on treatment 1 received only natural light during the day, while those on treatments 2, 3 and 4 received supplementary lighting during the night in addition to natural light during the day.

3. Food consumption by birds on treatment 2 was significantly higher at 56 days of age, followed by birds on treatments 1, 4 and 3.

4. The pattern of body weight gains was similar to the order of food consumption.

5. Efficiency of food utilisation was poorest for birds on treatment 2.

6. Mortality rates were not influenced significantly by the feeding regimen and lighting pattern.

7. Dressing percentage and proportion of abdominal fat were greatest for birds on treatment 2.     

Genotypic differences in speed and magnitude of response to ahemeral lighting

1. The paper compares between three genetically different lines in their egg weight and shell thickness response to a 28‐h cycle.

2. The response in shell thickness to ahemeral lighting was more rapid (2.2 d) than for egg weight (4.2 d).

3. Differences between genotypes were evident in both the speed and magnitude of response.

4. Overall, egg weight and shell thickness on the 28‐h cycle were 7% and 8% greater than on 24 h.

5. The allometric increase indicates that the increase in shell weight was on average 14% more than the increase in egg weight.     

Artificial light sources and their influence on physical activity and energy expenditure of laying hens

1. The influence of fluorescent and incandescent artificial lighting in a 16L:8D day/night schedule on number and intensity of movements, and on total, resting and activity‐related energy expenditure was investigated.

2. Fluorescent light showed the same positive correlation between light intensity and physical activity at all activity levels as was found previously for incandescent light.

3. Light‐dependent physical activity under fluorescent light was higher than under incandescent light at illuminances of 5 lux and above, indicating the fowl's ability to perceive qualitative light differences.

4. Total and activity‐related energy expenditure were positively associated with illuminance; resting energy expenditure was not influenced.

5. Total, resting and activity‐related energy expenditure were not statistically significantly different between light sources.

6. The results are discussed in relationship to Teichmuller's concept of adequate lighting and the characteristics of the fowl's visual system.     

Digestibility studies in broiler chickens: Influence of genotype,age, sex and method of determination

1. The influences of genotype, age and sex on droppings digestibility coefficients of a compound food were studied using male and female broiler chickens of three different genotypes at 2, 4 and 6 weeks of age.

2. Because the traditional method of determination of droppings digestibility coefficients of nitrogen may lead to systematic errors in estimating the feeding value of foodstuffs, a method is proposed to determine the ileal digestibility coefficients. The ileal method is compared with the droppings method for a mixed food and for two foodstuffs: wheat and solvent‐extracted soyabean meal.

3. Birds selected for efficient food conversion showed distinctly higher digestibility coefficients for all nutrients than birds selected for high growth potential or birds from a commercial strain.

4. The influence of age on digestibility coefficients was not consistent.

5. Female birds showed digestibility coefficients which were, in general, 3% higher than those of male chickens.

6. Interactions between genotype and sex and between genotype and age for energy metabolisability were the only interactions observed for digestibility measurements.

7. The method of determination influenced the amino acid digestibility coefficients of the mixed food and the relative feeding values of wheat and soyabean meal.

8. It is important to use well defined animals (genotype, sex, age) in evaluating foodstuffs.

9. The preferred method for determination of digestibility coefficients of nitrogen and amino acids is based on ileal sampling, although the differences in amino acid digestibility coefficients were small between methods.     

Effect of asymmetrical lighting on the body weight and carcase composition of laying hens and their influence on the efficiency of food utilisation

The body weight, carcase composition and component energy concentrations of laying hens were determined under 17L:7D and 2L:4D:8L:10D lighting regimens.

2. Hens subjected to 2L:4D:8L:10D lighting had lower body weights at end of lay and during most of the laying year, than the 17L:7D control birds.

3. Intermittently illuminated hens had similar absolute water, crude protein and ash contents to, but more water on a proportional basis than, controls.

4. Hens subjected to the 2L:4D:8L:10D lighting regimen had significantly less fat, in both absolute and proportional terms, than the controls.

5. There were no significant differences between the energy concentrations of the fat or fat‐free components of the two lighting groups.

6. There was no significant difference in the regression of fat content on body weight at end of lay for the intermittently and conventionally‐illuminated birds.

7. A prediction of the difference in daily energy requirement, based on egg output, body weight and mean daily body weight gain, very closely matched the actual difference in energy intake. This suggested that the more efficient food utilisation of intermittently‐illuminated hens could be explained by the lower body weight gain of these birds.     

Whitening of brown shelled eggs: Individual variation and relationships with age,fearfulness, oviposition interval and stress

1. Fearfulness, shell colour, incidence and degree of shell whitening and the interval between ovipositions were studied in two populations of 30 brown egg laying hens with family histories of a low or a high incidence of egg shell whitening.

2. Hens of the population with the high incidence of whitening appeared to be more fearful than hens of the population with the low incidence of whitening.

3. Brown colouration of the egg shell and the incidence and degree of shell whitening declined as the hens aged.

4. Brown colouration and egg shell whitening were most pronounced on the blunt ends of the eggs.

5. A large part of the variation in egg shell whitening was attributable to the individual (hen) component of variance.

6. Differences in egg shell whitening, between the two populations, were detectable throughout the 26 weeks of the experiment.

7. Oviposition intervals were similar for normal and coated eggs when birds were not exposed to disturbance.

8. Disturbance of hens increased oviposition intervals and the incidence and degree of shell whitening, to a similar extent, in both populations.

9. It is concluded that stress‐related egg retention is not the sole factor responsible for abnormal egg shell whitening. Shell whitening may occur as a consequence of the premature termination of shell pigmentation as well as a consequence of the retardation of oviposition which occurs when hens are disturbed.     

Traits influencing the hatching performance of Japanese quail eggs

1. Japanese quail eggs from moderately heavier sires showed superior fertility; while fertile eggs from moderately heavier dams hatched slightly better than the eggs from lighter dams.

2. Higher rates of fertility and hatchability of Japanese quail eggs were observed from parents of 10 to 19 weeks of age, with peak fertility and hatchability at 14 and 12 weeks of age, respectively.

3. Sex ratios of 1:2 to 1:5 gave comparable fertility and hatchability results.

4. The hatching performance of quail eggs from cage and deep litter reared breeders was comparable.

5. Fertility and hatchability were directly proportional to the egg weight.

6. Quail egg shell colour, tints and blotches were found to influence hatching performance.

7. Storing quail eggs at 16 ± 2°C and 75 ± 5% relative humidity for more than 4 d reduced hatchability.

8. Hatchability of eggs stored at room temperature was improved if they were sealed in polyethylene bags.

9. Provision of light during the first 14 d of incubation resulted in a photo‐acceleration of about 3.2 h.     

Genetic parameters of egg production,body weight and egg size in the red‐legged partridge

1. Heritability estimates of egg production, egg weight and body weight of red‐legged partridge were obtained.

2. Data from a population selected for increased egg production over four generations as well as from a random‐bred control population were available.

3. Heritability of egg number during the first production period was considerably higher than estimates for a second production period, induced by appropriate lighting.

4. Egg weight and body weight were highly heritable.     

Lighting and mortality rates in domestic fowl

1. Data from intermittent and conventional lighting trials were analysed to investigate the effect of daily illumination upon mortality during the laying period and in 49‐d‐old broilers.

2. Iiveability in laying hens was improved by the use of intermittent lighting: the degree of improvement was proportional to the reduction in daily illumination achieved by the intermittent programme.

3. The reduction in mortality with intermittent lighting in laying hens was not the result of intermittent lighting per se. Intermittent regimens which did not reduce daily illumination did not reduce mortality.

4. Mortality in both conventionally‐lit laying hens and 49‐d old‐broiler chickens increased with photoperiod.     

Metabolic and anatomical adaptations of light‐bodied chicks to intermittent feeding

1. Chicks of a light‐bodied strain were deprived of food on alternate days from 15 to 46 d of age.

2. Hyperphagia, amounting to twice the intake of control birds early in the experiment, occurred on the repletion day.

3. Final body weight attained 80% of that of the controls.

4. Body fat concentration decreased at first but returned to that of controls after 3 weeks.

5. A consistent hyperlipaemia was observed after food deprivation or restoration.

6. There was a marked increase in the digestive enzymes found in the small intestine, but not in the pancreas during the repletion day.

7. These responses may be considered as mechanisms to reduce the physiological manifestations of starvation.     

Light intensity,intermittent lighting and feeding regimen during rearing as affecting egg production and egg quality

1. Four light treatments and two rearing regimens were imposed on 4 breeds of laying hen, using 6144 birds in an 8‐room climate house.

2. Room treatments were a standard lighting pattern with intensities of 0.5, 2 and 15 lux and an intermittent pattern (3 h light: 3 h dark) at 15 lux. Within room treatments were ad libitum or rationed feeding during rearing and 4 breeds: ISA Brown, Hisex Brown, Shaver Brown and Hisex White.

3. Rationing during rearing, by holding intake at its 6‐week level from 6 to 14 weeks of age, was associated with significantly higher egg production and lower egg weight, but no effect on food intake, or egg output.

4. Intermittent lighting, using a repeated 3L:3D regimen was associated with higher egg weight, but a lower rate of lay, food intake, and total egg output.

5. The absence of a consistent response to light intensity, over the range 0.75 to 12.4 lux was in contrast with earlier work, and it is possible that modern prolific hybrids are more tolerant of low intensity than were earlier stocks.

6. Despite this result it is suggested that current recommendations of 10 to 20 lux in laying houses need not be changed, because such intensities are advisable on the grounds of welfare, staff working conditions and aesthetics.     

Battery cage shape: Its effect on diurnal feeding pattern,egg shell cracking and feather pecking

1. Battery cages 460 mm in depth (deep) were compared with 305 mm cages (shallow); the two shapes provided equal areas per bird.

2. More eggs were produced per hen housed from 30 to 70 weeks in the shallow cages; the difference approached significance.

3. The pattern of feeding activity over the day was significantly more U‐shaped in the shallow cages; this pattern accords more closely with physiological requirements.

4. Feather damage caused by pecking was slightly but significantly more severe in the deep cages at 70 weeks.

5. The proportion of cracked eggs (collected from 60 to 70 weeks) was significantly lower in the shallow cages.

6. The arrangement of the hens was such that within the shallow cages a higher proportion of birds was present in the front half.

7. It is suggested that some of the advantages conferred by the shallow cage may be related to the greater accessibility of the food trough.     

Intermittent lighting and feeding schedules for broilers incorporating long periods of darkness

1. Intermittent lighting and feeding schedules incorporating long periods of darkness and periods without access to food were applied to growing broilers.

2. Birds exposed to a 2 h light(L): 10 h dark(D) lighting schedule with feeding restricted to the light periods ate significantly less food and grew more slowly than conventionally‐reared birds. Satisfactory growth and efficiency of food utilisation were obtained by allowing these birds access to food during the dark periods.

3. Altering the lighting schedule to 2L:6D resulted in birds with food intakes and growth rates similar to those reared conventionally, even when feeding was restricted to the light periods.

4. Releasing birds from the light and food restriction for the 2 weeks preceding slaughter resulted in greater food consumption which was not characterised by significantly better growth or food utilisation.

5. Feeding a diet of high energy or pelleting a diet of low energy during the period of restriction increased food intake and improved growth rate.

6. The response of broilers to intermittent lighting and feeding was not significantly influenced by ambient temperature within the range 16 to 35 °C or by the energy concentration of the diet fed before the introduction of the intermittent schedule.     

Inheritance of body weight and rate of gain in Japanese quail

1. The effects of hatch date, location and sex on the body weight and rate of gain in Coturnix coturnix japonica were examined.

2. The data conformed to a mixed model and adjustments were made for the fixed effects sex, hatch date and location. Adjustment improved the precision of the estimates by reducing the error variances significantly.

3. Rearing equal numbers of birds from each family at different locations made the interactions negligible.

4. Weight gain was greater if illumination intensity up to 35 d was less.

5. Females were not heavier on the 1st day but were heavier on the 14th and 35th days than males.

6. Variance components and genetic parameters were estimated.     

Comparative mortality and predation in relation to egg production traits of Rhode Island Red,Black Australorp and Hyblack laying hens in scavenging production systems of rural Malawi

1. Black Australorp (BA), Rhode Island Red (RIR), and Hyblack (HB) birds were used in farm and field scavenging systems in Malawi, to study mortality through disease and predation in relation to laying performance.

2. Predation was higher in BA than HB.

3. Mortality through disease was higher in RIR than BA and HB.

4. Crossbred HB birds show the lowest combination of mortality and predation, suggesting a heterosis effect.

5. Mortality did not differ on farms and in field environments, suggesting an inability to improve biosecurity in farm conditions.

6. There was a positive relationship between eggshell strength and mortality. Calcium depletion from the birds’ bones, limiting foraging and escaping ability may be the explanation, which ultimately increases susceptibility to disease and predation.     

Photoperiod and seasonal influences on the growth of turkey hens

1. The influence of photoperiod and time of year on the growth of hen turkeys was investigated.

2. Photoperiod treatments consisted of computer simulations of day lengths which occur naturally in the spring and autumn of the year. Both photoperiod treatments were given to hens in the autumn and spring.

3. Data were collected for growth evaluations at 2‐ to 4‐week intervals to 16 weeks of age. No significant season × photoperiod interactions occurred.

4. The spring trial resulted in greater body weights and better food conversions (food/gain) than the autumn trial.

5. Simulated autumn daylengths resulted in greater body weights and improved food efficiency at 16 weeks of age compared with simulated spring daylengths.

6. The pattern of growth (period changes) was influenced by season, but not photoperiod.

7. Season and photoperiod both have important and independent influences on the growth of the turkey hen.     

Explanted embryo culture: In vitro and in ovo techniques for domestic fowl

1. Embryos of the domestic fowl (72 h old) have been explanted into shell‐less cultures or ‘surrogate’ eggshells, in order to investigate the possibility of rearing these embryos to hatching.

2. Rocking embryo cultures during the first half of incubation enhanced embryo growth.

3. Embryos explanted into ‘surrogate’ eggshells of either other individuals or other species have been successfully ‘hatched’.

4. A normal chorioallantois is formed in these surrogate eggshells. This enables a functional albumen sac to form and eggshell resorption to be achieved.

5. Embryos grown in ‘surrogate’ eggshells are slightly smaller than controls but otherwise normal.

6. The technique provides opportunities for genetic engineering experiments.     

Effects of cage shape,colony size,floor area and cannibalism preventatives on laying performance

1. Wire cages of variable width and depth, with a floor slope of 1 : 12, were used in two experiments to study the effects of cage depth, feeding space (= cage width), floor area, colony size and two methods of controlling cannibalism in White Leghorn x Australorp laying hens.

2. The least floor area (0.035 m²/bird) depressed production in two‐bird cages. Floor area had little effect on the performance of larger colonies.

3. Birds in colonies of three, four or six laid and survived equally well when feeding space/bird and floor area/bird were constant.

4. Production per hen d and food intake were higher, but return on estimated capital outlay was lower, with 102 mm than with 76 mm feeding space/bird when colony size and floor area/bird were constant.

5. Production and food intake of birds which were not treated to prevent cannibalism declined, and mortality increased, as cage depth increased from 385 to 915 mm concomitantly with increasing colony size from 2 to 7 birds and decreasing feeding space from 152 to 43 mm/bird.

6. Increasing cage depth did not increase the proportion of cracked eggs.

7. Mortality was higher among birds fitted with plastic spectacles than among debeaked birds.     

Comparison of nutritive values of groundnut oil cake and Niger oil cake for laying pullets

1. The nutritive value of Niger oil cake (Guizotia abyssinica, Cass.) as a protein supplement for layers’ diets has been assessed.

2. Replacing groundnut oil cake (GNC) by Niger oil cake (NC) on an isonitrogenous basis, did not affect egg production, egg weight or the amount of food required per dozen eggs.

3. The percentage retention of nitrogen from diets containing 30% GNC or 30% NC was similar.

4. The ME value of NC used was 3025 kcal/kg.

5. It is concluded that NC can replace GNC in layers’ diets.