G. C. Perry

Feather pecking and cannibalism in a caged layer flock

1. The progress of feather pecking and cannibalism was recorded from hatching to end of lay in a flock of caged layers and the influence of group size, floor area allowance and cage tier upon the incidence of these activities during lay assessed. 2. The largest group suffered more cannibalism and feather pecking than smaller groups, floor area allowance and tier being less important factors. 3. A significant trend was found for one death from cannibalism to be followed by more in the same cage.4. It was concluded that feather pecking and cannibalism are separate phenomena, although the same cage conditions increased the incidence of both. 5. Cannibalism may be divided into vent pecking and cannibalism affecting other parts of the body, the former is independent of feather pecking and the latter, though usually preceded by feather pecking, is only indirectly associated with it.

Leg health and performance of broiler chickens reared in different light environments

1. The effects of light source and intensity on leg health and performance of female ROSS 308 broiler chickens were investigated in a 2 × 2 experimental design (8 groups of 275 chicks) of two light sources (Osram biolux and Osram warm-white) and two light intensities (5 and 100 clux, adjusted to fowl-perceived illuminance). 2. At 41 d of age, body weight, gait-score, footpad dermatitis and hock-burn were measured on 50 birds from each light environment. In addition, weekly feed intake and body weight were determined on a group basis and mortality was recorded continuously. 3. The light environment did not affect the severity of the gait-score or hock-burns. The risk of moderate to severe lameness and hock-burns increased with body weight. Birds weighing more than 2400 g had an increased probability of moderate footpad lesions in biolux light. 4. Weight and gait-score, as well as gait-score and hock-burn were positively correlated. Podo-dermatitis was weakly correlated with hock-burn, which contradicts earlier findings. The light environment did not affect feed intake, body weight or mortality. 5. The light sources and intensities employed in this study did not adversely affect production or leg health of broiler chickens reared semi-commercially.

The effects of restraint, handling, simulated and real transport in the pig (with reference to man and other species).

Abstract Whilst the processes and effects of animal transportation can be described in direct terms, they can also be regarded as fear-inducing challenges. Some of the physiological and behavioural responses of pigs to aspects of simulated and real transport are examined. Evidence from other species is used to support data from pigs to show that the cardiovascular system is affected following environmental and emotional challenge. Detailed responses of pigs to simulated transport are described. The effects of vibration and noise are described and reference is made to the use of conditioning techniques which indicated that pigs developed an aversive response to vibration. The interaction between feeding and pig response to vibration is also described.

A model for predicting the age at sexual maturity for growing pullets of layer strains given a single change in photoperiod

A model is presented which will predict mean age at first egg (AFE) for pullets of laying strains reared under non-limiting environmental conditions but exposed to a single change in photoperiod during the rearing stage. An initial analysis of 12 previously reported trials involving a wide range of genotypes showed that the response to an increase in photoperiod is not simply the inverse of the response to an equal decrease in photoperiod applied at the same age. Maximum sensitivity to a reduction in photoperiod was found shortly before onset of lay, whereas maximum sensitivity to an increment in photoperiod was observed at around 10 weeks of age. Two experiments were conducted to provide further data. The first compared the effect of 3-h increases in photoperiod from 8 h to 11 h or from 11 h to 14 h with the double increment from 8 h to 14 h and also tested a reduction from 11 h to 8 h, all imposed at 17 weeks of age. AFE was advanced to a similar extent by the changes from 8 to 11 h and from 11 to 14 h (9.8 and 10.9 days respectively). Response to the double increment was not additive: AFE on this treatment was 13.3 days earlier than for constant 8 h controls. Reduction in photoperiod from 11 to 8 h at 17 weeks delayed AFE by 18.7 days compared with constant 11-h controls. In the second experiment, pullets of two strains were transferred from 8 to 16-h photoperiods and from 16 to 8 h at 5, 7, 9, 15, 17 and 19 weeks of age. Controls were kept on constant 8 and constant 16-h days. Transfer from 8 to 16-h photoperiods at 5 weeks of age had no effect on AFE. At 7 weeks there was a bimodal response with some pullets subsequently showing advanced maturity and others not. Maximum stimulation of early maturity (31 days on average for the two genotypes) was obtained at 9 weeks of age and response to stimulation declined linearly with age thereafter. The delay in AFE resulting from a reduction in photoperiod (16 to 8 h) increased linearly between 0 and 15 weeks. At 17 and 19 weeks, the response was bimodal, with some pullets maturing at the same age as long-day controls and others showing delayed maturity. Using all this evidence and some other unpublished data, a model is developed to predict AFE as a function of mean photoperiod and change in photoperiod during the rearing phase. Elements are incorporated to allow for the insensitivity of pullets younger than 50 days to an increase in photoperiod and the effect observed late in rearing when a change in photoperiod comes too late to alter AFE for the most precocious individuals in a flock. Two coefficients are required to adjust for genotype. One describes mean AFE for the genotype when reared on constant daylength and the other defines the rate at which age effects the response to a single change in photoperiod.

A model for the effect of constant photoperiods on the rate of sexual maturation in pullets

1. This paper reviews evidence from 15 experiments, reported over a span of 44 years, in which pullets were reared from hatching to sexual maturity on 2 or more constant photoperiods. 2. The evidence strongly indicates that earliest age at first egg (AFE) was observed when pullets were held on constant 10 h days (though earlier maturity is easily induced by increasing the photoperiod during rearing). The pair of equations which best describe the relationship between AFE (y, d) and photoperiod (x, h) are for x < or = 10 h, y = 175.8-1.731x; for x > or = 10 h, y = 155.5 + 0.301x. 3. This 2-straight-line model, hinged at 10 h, should be used in preference to curvilinear models published earlier, which wrongly predict that pullets reared on long days (14 h to 17 h) mature faster than birds reared on constant 10 h.

Effects of environmental enrichment, fluorescent and intermittent lighting on injurious pecking amongst male turkey poults

1. Under commercial and experimental conditions domestic turkeys often cause injuries to pen-mates by repeated pecking, sometimes fatally. Environmental enrichment or lighting manipulations might be used to mitigate such injurious pecking. 2. This study examined responses to 4 treatments (2 rooms/treatment) of 8 groups of 100, non-beak trimmed, non-desnooded, male domestic turkeys from 1 to 35 d of age. 3. Birds of 1 treatment were reared under conditions approximating to commercial rearing (12L:12D incandescent, Control) whereas the experimental treatments were 12L:12D incandescent plus supplemental ultraviolet radiation, straw supplementation of litter, pecking substrates and visual barriers (Enriched), 12L:12D fluorescent lighting (Fluorescent), and 2(2L:3D):2L:12D incandescent (Intermittent). 4. Compared to control birds, the incidence of injuries caused by wing or tail pecking were both lower in the Enriched but not significantly different in the Fluorescent or Intermittent. 5. Injuries caused by head pecking did not occur in the Enriched rooms but were observed in at least 1 of the rooms with Control, Fluorescent and Intermittent treatments. 6. Despite considerable environmental differences between treatments, there was remarkable consistency within each type of injurious pecking in age at which injuries were 1st recorded (wing pecking, 9.38+/-1.31 d; tail pecking, 20.43+/-2.42 d; head pecking, 27.8+/-2.13 d). The roles of feather emergence, hierarchy formation in wild turkey poults and appearance of feathers are discussed as possible explanations of these consistencies.

Effect of photoperiod on the mean oviposition time of two breeds of laying hen

1. Oviposition times were recorded for brown and white egg-laying hybrids under 8, 10, 13 and 18 h photoperiods. 2. Mean oviposition time for both breeds was advanced relative to dusk by approximately 0.5 h for each 1 h extension of photoperiod. 3. Mean oviposition time for the brown egg hybrid was 1.2 to 1.4 h earlier than that of the white egg hybrid under each lighting regimen. 4. A genetic difference in phase setting of the Open Period for Luteinising Hormone (LH) release is the likely reason for the difference in mean time of lay of the two breeds. The difference is possibly one between brown and white hybrids generally, rather than between the particular varieties of hen used in this trial. 5. The proportion of the day in which eggs are laid is shorter under long photoperiods presumably because light at the end of the photoperiod inhibits the pre-ovulatory surge of LH.

Effect of constant and of changing photoperiods on age at first egg and related traits in pullets

1. The effects of constant photoperiods and of single (5 h) changes in photoperiod applied at 12 or 17 weeks of age upon age at first egg (AFE) were studied using ISA Brown and Shaver 288 pullets. 2. Birds reared from 2 d of age until after maturity on constant 10 h photoperiods matured 8 d earlier than birds reared on constant 8 h and 5 d earlier than the average for 13 or 18 h photoperiods. 3. A single increment in photoperiod from 8 to 13 h advanced AFE by 23 d (compared to 8 h constant day controls) when applied at 84 d, but by only 6 d when given at 119 d. An increase in photoperiod from 13 to 18 h advanced AFE by only 4 d, averaged across breeds and age at increase. A reduction in photoperiod from 13 to 8 h delayed AFE by 22 d when given at 84 d and by 16 d at 119 d. A similar 5 h reduction in photoperiod, but from 18 to 13 h, retarded maturity by 11 d in ISA Brown pullets, but only when given at 84 d, and delayed AFE in Shaver 288 by 12 d, but only when given at 119 d. This interaction may be partly explained by the different physiological stages reached by the two breeds when the photoperiod was changed. 4. Under constant daylengths cumulative food intake before first egg was positively correlated with photoperiod, but the early AFE for birds on 10 h photoperiods resulted in this group having the lowest cumulative food intake to first egg. 5. A 5 h increase in photoperiod at 84 d significantly reduced the food consumed to first egg, but had no effect when given at 119 d. A 5 h decrease in photoperiod generally increased the food consumed to first egg, but the effect was only significant when the daylength was reduced from 13 to 8 h at 119 d. Food intake to first egg in birds subjected to a change in photoperiod was highly correlated with AFE. 6. The data confirm that sexual development in growing pullets responds more to changes in photoperiod than to the absolute daylength, that changes made at different daylengths are not equivalent and that sensitivity changes with age.

Comparative study of the photopic spectral sensitivity of domestic ducks (Anas platyrhynchos domesticus), turkeys (Meleagris gallopavo gallopavo) and humans

1. The photopic spectral sensitivity of domestic ducks and turkeys was determined using an operant psychophysical technique. Spectral sensitivity was determined over a range of specified wavelengths, including UVA, between 326 < λ < 694 nm and the results were directly compared with human spectral sensitivity measured under similar experimental conditions. 2. Domestic ducks and turkeys had similar spectral sensitivities to each other, and could perceive UVA radiation, although turkeys were more sensitive to UVA than ducks. For both species, peak sensitivity was between 544 < λ < 577 nm, with reduced sensitivity at λ = 508 and 600 nm. Both ducks and turkeys had a very different and broader range of spectral sensitivity than the human subjects tested. 3. Spectral sensitivity and UVA perception in these avian species are discussed in relation to their visual ecology and the mechanisms controlling neural processing of colour information.

EFFECT OF TIMING AND SIZE OF PHOTOPERIOD CHANGE ON PLASMA FSH CONCENTRATION AND THE CORRELATION BETWEEN FSH AND AGE AT FIRST EGG IN PULLETS

1. ISA Brown pullets were transferred at 6, 9, 12, 15, 18 or 20.3 weeks of age from an 8 h photoperiod to an 8, 10, 13 or 16 h photoperiod. Plasma follicle stimulating hormone (FSH) concentration was measured at transfer at 7 and 14 d afterwards, and age at first egg (AFE) was recorded. 2. Plasma FSH concentration in pullets reared on constant 8 h photoperiods generally increased with age but with a trough at 12 weeks. Plasma FSH increased during the first 14 d of photostimulation to a significantly higher concentration, compared with constant 8 h controls, when the photoperiod was increased to 13 or 16 h at 9, 12 or 15 weeks; but for the increase from 8 h to 10 h photoperiods FSH was only significantly higher than controls when the change was made at 12 weeks. 3. The change in plasma FSH concentration 14 d after photostimulation was significantly correlated with mean AFE (reported in Lewis et al., 1997) and appears to be a better predictor of gonadal development than concurrent changes in plasma LH concentration previously reported (Lewis et al., 1994).