Effect of oestradiol-17 beta on perineal and neck skin glands in heifer calves.

Ten 16-week-old Friesian x Hereford heifer calves were split into experimental and control groups. Experimental animals were given an implant of oestradiol-17 beta in the ear whilst controls were given blank implants. They were killed 14 days later. After implantation the experimental group had consistently greater (P less than 0.01) plasma concentrations of oestradiol-17 beta than the control group. After death, sebaceous gland volume in the perineal region was greater (P less than 0.01) in the experimental than in the control group, whereas sebaceous gland volume in the neck was smaller (P less than 0.01). Sweat gland volume in the perineal region was greater (P less than 0.01) in the experimental than in the control group. There was no difference between groups in the volume of sweat glands in the neck.

A quantitative morphological study of the bovine vaginal epithelium during the oestrous cycle.

Samples were collected post mortem from 28 cycling parous cows. At all stages of the oestrous cycle, the cranial vaginal epithelium was thinner (P less than 0.001), had fewer cell layers (P less than 0.001) and proportionally more superficial columnar cells (P less than 0.001) than more caudal regions. At all stages of the cycle there were more intraepithelial lymphocytes caudally than in more cranial regions (P less than 0.001). At oestrus the proportion of superficial columnar cells was maximal, having increased from the late dioestrus proportions of 1, 29 and 40 per cent of all superficial cells to 15, 54 and 83 per cent in caudal, middle and cranial regions, respectively (P less than 0.02). However, the epithelial thickness in all regions of the vagina was greatest at metoestrus (P less than 0.02). At this stage, the number of cell layers was greater than at any other stage (P less than 0.05).

Amount and distribution of vestibular-associated lymphoid tissue in calves and adult cows.

Normal reproductive tracts were obtained from 11 adult cows, five eight-week-old and five six-week-old heifer calves. Lymphoid nodules and aggregations (loci) were localised in vestibules by immersion in 2 per cent acetic acid. Adults had significantly more loci (P less than 0.001) than eight- or six-week-old calves, there being means of 194.6, 44.2 and 7.4 loci per vestibule, respectively. In all age groups there was a greater concentration (number cm-2) of loci along the median ventral groove than the side walls (P less than 0.001), and in the caudal third of the vestibule than in the middle or cranial thirds (P less than 0.001). The concentrations of loci were the same in adults and eight-week-old calves but significantly lower in six-week-old calves (P less than 0.01).

Rate of discharge and morphology of sweat glands in the perineal, lumbodorsal and scrotal skin of cattle.

The rates of evaporation of moisture from the skin in the lumbodorsal, perineal and scrotal regions of cattle were measured in thermoneutral and high environmental temperatures. The rates of evaporation from the perineal and scrotal regions of heifers and bulls were significantly (P < 0.001) greater than those from the lumbodorsal areas. The lumbodorsal rate of evaporation increased significantly (P < 0.001) when cows and bulls were transferred from a thermoneutral to a hot environment and the rate of evaporation from the scrotum of bulls showed a similar increase; the rate of evaporation from the perineum of cows increased to a smaller extent (P < 0.05) under the same conditions. The rate of evaporation from the perineum of cows reached a maximum on the day of oestrus but the stage of the oestrous cycle had no effect on the lumbodorsal rate of evaporation.

Responses of two genotypes of chicken to the diets and stocking densities typical of UK and 'Label Rouge' production systems: I. Performance, behaviour and carcass composition.

'Label Rouge' (LR) chickens are reputed to possess improved sensory characteristics compared with birds reared under intensive conditions. The effects on body weight, food utilisation, behaviour and carcass composition, of genotype (Ross I vs ISA '657'), diet (conventional UK broiler vs LR) and stocking density (17.0 birds m(-2),vs 4.25 birds m(-2)) were evaluated in a 2 × 2 × 2 experiment. ISA birds were grown to 83 days, and compared with Ross birds grown to 48 days; additionally ad libitum and control-fed Ross birds were grown to 83 days. Performance and behaviour parameters were assessed empirically. The effects on carcass composition were evaluated using standardised carcass dissection techniques and analysed by analysis of variance. ISA birds grown under LR conditions to 83 days had similar body weights to Ross birds grown under UK broiler conditions to 48 days, but LR birds consumed more food, and converted food into meat less efficiently. LR birds had no mortality, whilst UK broiler mortality was 11.3%. Under similar conditions, Ross birds had a faster body weight gain, a larger food intake, but more efficient food conversion ratio and higher incidence of mortality. Birds stocked 17.0 m(-2) had lower body weights, consumed less food and, when fed UK diets, converted food less efficiently than birds stocked 4.25 m(-2). Both genotypes had a faster growth rate on UK diets, similar food intakes, and, as a result, better food conversion than birds given LR diets. LR and UK broiler birds had similar carcass component weights, breast meat yields, and total meat yield, but LR birds had less meat on the frame, larger drumsticks and more meat on the wings. Under similar conditions, ISA birds had a larger percentage of wing and total bone, but a smaller percentage of breast meat and total meat yields. When Ross birds had controlled growth, total meat, bone and skin yields were similar to those of ISA birds. Birds stocked 4.25 m(-2) had more breast meat and larger frames than, but similar meat, bone and skin yields to, birds stocked 17.0 m(-2). Most carcass components were heavier in birds fed UK broiler diets, but, on a percentage basis, these birds had larger thighs, but smaller drumsticks.

Responses of two genotypes of chicken to the diets and stocking densities of conventional UK and Label Rouge production systems-II. Sensory attributes.

French Label Rouge quality chickens are reputed to possess improved sensory characteristics compared with birds reared under intensive conditions. The effects of genotype, diet, stocking density and age on eating quality were evaluated in a 2 × 2 × 2 experiment. The results suggest that genotype, diet, age and, to a lesser extent, stocking density can influence eating quality. The most pronounced sensory differences between the two genotypes were in the appearance and texture of the cooked meat. In particular, scores for toughness were higher for breast meat from Ross than ISA birds, though the opposite effect was observed for the thigh meat. Diet and age also affected texture, with the breast meat from chickens on the Label Rouge diet, or from older birds, having lower scores for toughness. Effects on odour and flavour were generally small and subject to genotype × diet interactions. The odour and flavour intensity of breast meat increased with age, while the odour intensity of thigh meat was higher in birds reared at low stocking density.

Effect of ultraviolet radiation on the performance of intact male turkeys.

Ultraviolet (UV) sensitivity in birds has been shown to be intrinsically involved in the selection of mates; UV may, therefore, also play a role in the establishment and maintenance of social hierarchies in intensively housed turkeys. Cereal seeds and straw are known to reflect UV, and turkeys may use these cues for foraging and exploratory behaviors. A series of trials was conducted to see if supplementation of the photoperiod (12 h at various white light intensities) with UV radiation (0.06 to 0.16 W/m2 at floor level) and regular supplies of straw to the litter allow a better recognition of individuals within a flock, enrich the environment by the provision of new pecking material and of radiation across the whole range of avian sensitivity, and, as a consequence, reduce the incidence of injurious pecking in male turkeys that have not been beak-trimmed, detoed, or desnooded. Body weight gain, feed intake, feed conversion efficiency, and leg integrity were generally not significantly affected by UV supplementation and environmental enrichment. In contrast, the provision of UV radiation, simultaneous with a 12-h photoperiod of white light at intensities of <70 lx to 5 wk and of 10 lx to 20 wk, and the regular addition of straw to the litter, significantly reduced the incidence of culling because of injurious pecking. However, complex interactions among UV supplementation, white light intensity, and material environmental enrichment precluded a simple recommendation to solve the problem of injurious pecking.

Supplementary dim light differentially influences sexual maturity, oviposition time, and melatonin rhythms in pullets.

The addition of two 3-h periods of very dim light, one before and one after a normal 8-h photoperiod, advances sexual maturity in pullets by about a week. This trial tested the hypothesis that dim light given before a short day of normal intensity is linked to form a more stimulatory day length and that dim light given after it is photosexually ignored. Pullets were reared from 2 d of age on 8-h photoperiods. From 10 wk, they were continued on 8-h photoperiods, transferred to 16 h, or given an 8-h period of dim light (0.09 lx) immediately before or after the main 8-h photoperiod. The bright/dim and dim/ bright groups matured at the same age, thus disproving the hypothesis tested. Both groups matured 1 wk earlier than the 8-h controls but 5 wk later than birds transferred to 16-h photoperiod. Oviposition time was similar for 8-h controls and bright/dim hens and delayed by 3 h for 16-h birds, but phase advanced by 2.4 h for dim/bright hens. Plasma melatonin rhythm was phase-advanced by about 5 h in the dim/bright hens and retarded by about 5 h in the bright/dim hens, suggesting a 13-h subjective day. However, these treatments were not regarded as fully stimulatory, as a transfer to a normal 13-h photoperiod at this age advances maturity by 5 to 6 wk. These findings show that the addition of a period of dim light to a normal nonstimulatory photoperiod differentially affects the clocks that control sexual maturation, plasma melatonin concentration, and oviposition time.

Light intensity and age at first egg in pullets.

Layer strain pullets were reared on litter and given an 8-h photoperiod to 10 wk of age. They were then transferred to cages in which light intensity at the feed trough varied from 5 to 14 lx. Thirty birds continued on 8 h light (L):16 h dark (D) (negative controls), and another 30 birds were given 14L:10D (positive controls). Two other groups of 30 birds were given a regimen of 3 dim:8 L:3 dim:10 D with intensity during the dim phase ranging from 0.03 to 0.42 lx (very dim) or from 0.6 to 3.0 lx (marginal). Mean age at first egg (AFE) differed by 30 d between the positive and negative controls. Birds receiving very dim lighting matured 10 d earlier than the negative controls but 20 d later than positive controls. It is concluded that either the very dim light was itself nonstimulatory but had a phase shifting effect upon the biological clock that caused the 8-h normal light to fall partly in the photoinducible phase, or the first 3 h of very dim light was added to the bright phase to form an 11-h photoperiod. Birds in the top tier of the room with marginal supplementary lighting received 1.7 to 3.0 lx and matured at the same age as the positive controls, whereas those in the bottom tier received 0.6 to 0.9 lx and matured at the same age as the negative controls. Birds in the middle tier showed an intermediate AFE. It is concluded that the threshold intensity at the feed trough for white light stimulation of the photoperiodic mechanism in caged pullets lies between 0.9 and 1.7 lx. However, very dim lighting, below the threshold required for stimulation of a photoperiodic response, may shift the biological clock with unexpected consequences and, as a result, there is no known intensity of dim light that can be equated with darkness for all purposes.

A pheromonal function for the perineal skin glands in the cow.

Two cows with synchronised oestrous cycles were housed with a Friesian bull. During the midcycle period of the cows, one cow was given an intradermal injection of adrenaline in the perineal region. This caused local sweat gland discharge. The other cow was treated with water. The number and types of bull-to-cow behaviours were recorded before, during and after the day of treatment. This was repeated at three-weekly intervals for a total of four times. On the day of treatment the bull directed a greater proportion of olfactory behaviours towards the adrenaline-treated cow than the other cow (P less than 0.05). There was no difference between the cows before or after the day of treatment. The above experiments were repeated with a Hereford bull who showed the same response as the Friesian for the first two but not the last two experiments. The increased proportion of bull olfactory behaviours elicited by an increased perineal skin gland discharge, adds support to our hypothesis that the perineal skin glands are the source of an oestrous pheromone in the cow.

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 x 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.

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 < lambda < 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 < lambda < 577 nm, with reduced sensitivity at lambda = 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.

Growth and food intake of broilers under various lighting regimes.

1. Growth rates and daily food intakes of small, sexed groups of broilers were compared under different photoperiodic regimes during the period from 28 to 49 d of age. 2. Reduction in the duration of illumination did not impair growth rate. 3. The sexes showed a differential response to the treatments. 4. There was evidence that the enhanced performance of females was due to an improvement in food conversion efficiency.

Glossary of avian photoperiodic terminology and methods of expressing lighting regimens.

1. A list of definitions is given for terms commonly used in animal photoperiodism. 2. A list of symbols and abbreviations commonly used in avian photoperiodism is included. 3. Methods are given for a standardised description of lighting regimens.

Response of laying hens to asymmetrical interrupted lighting regimens: reproductive performance, body weight and carcase composition.

1. The performance of brown egg laying hens was compared under conventional and asymmetrical interrupted-lighting conditions. 2. Egg numbers and mean weight were similar under the two conditions, provided the apparent day perceived by the hen was the same under both lighting treatments. 3. Daily food intakes of intermittently-illuminated hens were not significantly lower than those of conventionally-lit birds. However, the reductions were of the magnitude reported in the literature and observed under commercial conditions. 4. Shell quality was unaffected by interrupted lighting in the period up to 60 weeks of age in two of the 4 genotypes studied. All breeds had lower shell weights under interrupted lighting in the last three months of lay. 5. Intermittently-lit hens had lower body weights, which approached significance, and significantly less carcase fat. There were no differences in ash, protein (N x 6.25) or water contents of the carcases, or in fat content at a given body weight. 6. There were no significant differences in the production responses of the 4-brown-egg hybrids to interrupted lighting. 7. Diets with differing concentrations of energy and protein were included in both trials, but there was no evidence of interaction between these nutritional treatments and the lighting treatments.

Response of laying hens to asymmetrical interrupted lighting regimens: physiological aspects.

1. There were no significant differences in the mean time of oviposition, distribution of ovipositions over the 24 h or proportion of eggs laid in the modal 8 h when conventionally-lit hens were compared with hens which received interrupted lighting with the same apparent daylength. 2. Intermittently-lit hens performed 25% less feeding activity than conventionally-lit hens, but without a significant reduction in mean food intake. There were genetic differences in response of feeding rate to interrupted lighting. 3. Intermittently-illuminated hens consumed about 20% of their food during the scotoperiods which interrupted the apparent day of a 1.5L:0.5D:10(0.5L:0.5D):4L:8D regimen, although there was significant genetic variation from 10 to 22%. None of the genotypes ate during the 8-h night. 4. Across 4 genotypes neither crop weight nor rate of crop emptying was affected by the lighting treatments, although a heavier mean crop weight under interrupted lighting approached significance in one breed (P less than 0.10). 5. Interrupted lighting did not cause any ocular disorders.

Effects of interrupted lighting regimens on the feeding activity of the laying fowl.

Segmentation of the main light period of an 8L:4D:2L:10D regimen into 30 min light, 30 min dark did not affect total feeding activity, rate of feeding or total intake of laying hens. When 15 min light and 45 min dark was provided each hour feeding activity and food intake were reduced, while rate of feeding and feeding during the dark periods increased. No feeding occurred in the 10 h 'night'. Hens subjected to interrupted lighting showed less feeding activity than those on a 14L:10D regimen. Insertion of a 4 h dark period in the 14 h subjective day of laying hens increased their rate of feeding, but reduced total intake. The pattern of feeding activity depended on the position of the 4 h dark period. The largest modification of feeding activity occurred on a 8L:4D:2L:10D regimen; 20% of activity occurred in the last 2 h of the apparent day. Feeding occurred during the 4 h dark period, but not during the 10 h 'night'.

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.

Responses of immature pullets to repeated cycles of gradual increases and abrupt decreases in photoperiod.

1. Growing pullets were reared on constant 8, 11 or 14 h photoperiods or given 12 daily increments of 30 min followed by an abrupt 6 h decrease in photoperiod in 14 d cycles from 2 d of age to sexual maturity. 2. Birds on the experimental lighting programme matured earlier than constant 8-h controls, later than 11-h controls but at the same age and body weight as constant 14-h controls. 3. Weight of the first egg was correlated with age at first egg. 4. It is assumed that potential advances in maturity for the experimental birds from the 30 min increments in photoperiod were cancelled by the retarding influences of 6 h decreases in photoperiod, resulting in their maturity being similar to that of birds reared on a constant daylength equal to the longest photoperiod reached during the cycle.