Developmental temperature affects the expression of ejaculatory traits and the outcome of sperm competition in Callosobruchus maculatus.

The outcome of post-copulatory sexual selection is determined by a complex set of interactions between the primary reproductive traits of two or more males and their interactions with the reproductive traits of the female. Recently, a number of studies have shown the primary reproductive traits of both males and females express phenotypic plasticity in response to the thermal environment experienced during ontogeny. However, how plasticity in these traits affects the dynamics of sperm competition remains largely unknown. Here, we demonstrate plasticity in testes size, sperm size and sperm number in response to developmental temperature in the bruchid beetle Callosobruchus maculatus. Males reared at the highest temperature eclosed at the smallest body size and had the smallest absolute and relative testes size. Males reared at both the high- and low-temperature extremes produced both fewer and smaller sperm than males reared at intermediate temperatures. In the absence of sperm competition, developmental temperature had no effect on male fertility. However, under conditions of sperm competition, males reared at either temperature extreme were less competitive in terms of sperm offence (P(2)), whereas those reared at the lowest temperature were less competitive in terms of sperm defence (P(1)). This suggests the developmental pathways that regulate the phenotypic expression of these ejaculatory traits are subject to both natural and sexual selection: natural selection in the pre-ejaculatory environment and sexual selection in the post-ejaculatory environment. In nature, thermal heterogeneity during development is commonplace. Therefore, we suggest the interplay between ecology and development represents an important, yet hitherto underestimated component of male fitness via post-copulatory sexual selection.

Prioritization based on neutral genetic diversity may fail to conserve important characteristics in cattle breeds.

Conservation of the intraspecific genetic diversity of livestock species requires protocols that assess between-breed genetic variability and also take into account differences among individuals within breeds. Here, we focus on variation between breeds. Conservation of neutral genetic variation has been seen as promoting, through linkage processes, the retention of useful and potentially useful variation. Using public information on beef cattle breeds, with a total of 165 data sets each relating to a breed comparison of a performance variable, we have tested this paradigm by calculating the correlations between pairwise breed differences in performance and pairwise genetic distances deduced from biochemical and immunological polymorphisms, microsatellites and single-nucleotide polymorphisms. As already observed in floral and faunal biodiversity, significant positive correlations (n=54) were found, but many correlations were non-significant (n=100) or significantly negative (n=11). This implies that maximizing conserved neutral genetic variation with current techniques may conserve breed-level genetic variation in some traits but not in others and supports the view that genetic distance measurements based on neutral genetic variation are not sufficient as a determinant of conservation priority among breeds.

Effect of sight barriers in pens of breeding ring-necked pheasants (Phasianus colchicus): I. Behaviour and welfare.

1. The study investigated the effects of providing sight barriers in breeding pens on pheasant mortality, feather damage and behaviour. 2. Data were collected from 11 conventional pens (control) and 11 pens with additional sight barriers (barrier) over the course of a ten week breeding season. Each pen contained 8 males and 56 females at the beginning of the season. 3. There was a higher rate of mortality in males (6 x 25%) than females (2 x 11%) that was unaffected by treatment. 4. Feather damage increased over the breeding season and both male and female pheasants showed better feather condition in the pens with barriers at the end of the season. 5. The pheasants spent most of their time walking or standing. Providing barriers increased perching, but reduced preening. 6. The provision of sight barriers had no effect on the incidence of courtship and mating, but did reduce aggressive interactions such as pecking and chasing. 7. The study provides baseline data on the behaviour of breeding pheasants under these husbandry conditions, and suggests that barriers may improve pheasant welfare by reducing potentially harmful aggressive interactions, without affecting activity patterns or reproductive behaviour.

Effect of sight barriers in pens of breeding ring-necked pheasants (Phasianus colchicus) II. Reproductive parameters.

1. The effects of sight barriers in the pens of breeding ring-necked pheasants were investigated on a commercial game farm over a 10-week laying season. 2. Reproductive performance was recorded as egg production, numbers of eggs rejected for hatching together with measures of fertility, embryonic mortality and hatchability for 11 pens with barriers and 11 pens that were left open and acted as controls. 3. Egg production per pen and the numbers of rejected eggs were not significantly affected by the presence of the barriers. 4. Fertility was significantly higher and persisted for longer in the barrier pens, particularly towards the end of the laying season. 5. Embryonic mortality was unaffected by the presence of the barriers but hatchability was significantly lower in the open pens, which was associated with lower levels of fertility. 6. Establishing sight barriers in breeder pens for commercial pheasants would appear not only to offer improved welfare but also significant commercial advantages.

Double-yolked pheasant eggs provide an insight into the control of albumen secretion in bird eggs.

1. The possible role of the presence of the yolk in stimulating secretion of albumen was investigated. 2. Double-yolked and single-yolked pheasant (Phasianus colchinus) eggs were opened to determine the masses of the shell, albumen and yolk(s). 3. In double-yolked eggs, the two yolk masses were not significantly different. Albumen mass was increased above that expected from an egg with a single-yolk of comparable size but below that expected from an egg having a mass of the combined yolks. The mass of shell per unit area reflected the mass of the initial mass of the egg irrespective of the number of yolks. 4. The additional mass of albumen is unrelated to yolk or initial egg mass. It is postulated that in double-yolked eggs the oviduct is mechanically stimulated by the presence of both yolks, which empties the stores of water-soluble albumen proteins in the magnum wall. Such stores are insufficient to provide the same amount of protein for the two yolks.

Yolk sac, body dimensions and hatchling quality of ducklings, chicks and poults.

1. One-day-old chicks of Pekin duck, turkey, layer fowl and broiler fowl were examined for bacteria in the yolk sac and yolk fluid. 2. Whole hatchling, yolk-free hatchling and yolk sac weights were recorded for all species along with crown-rump length and beak-tip to toe-tip length. 3. Bacteriology revealed positive results for the whole yolk sacs of 43 to 64% of the birds in the sample of ducklings, poults and layer chicks. Broiler chicks had a 6.6% incidence of bacteria isolated from the whole yolk sac. By contrast, there were very few positive results from swabs of yolk fluid for any of the bird types. 4. The presence of bacteria in the yolk sac of hatchlings suggests that there is colonisation, rather than infection, of the yolk sac membrane during the hatching period or the first few hours post-hatching. Isolation of bacteria from the yolk sacs of young chicks might no longer be considered as solely indicative of yolk sac infection but further research is required to confirm this result. 5. Contrary to what is being suggested in commercial practice relationships between linear dimensions and hatchling weight suggest that measurement of chick length is at best a very crude measure of chick quality.

Effects of egg mass and percentage mass loss during incubation on hatchability of eggs of the rock partridge (Alectoris graeca).

1. The effects of initial egg mass (IEM) and percentage mass loss during incubation (%ML) on hatchability of rock partridge eggs were investigated. 2. Eggs at the extremes of IEM had lower fertility and embryonic mortality. 3. Eggs at the extremes of %ML also had low fertility and hatchability was disproportionately reduced in eggs that had lost less mass during incubation. 4. Chick mass was a function of both IEM and mass lost during incubation. 5. In these respects rock partridge eggs are similar to that of other domesticated species of poultry.

Influence of mating sex ratio in commercial pheasant flocks on bird health and the production, fertility, and hatchability of eggs.

1. The effects of two mating ratios (8:1 and 12:1 females:males) on bird health, egg production and quality, fertility (employing macroscopic and microscopic techniques) and hatchability were examined for pheasants (Phasianus colchinus) on a commercial game farm, to provide a baseline data set for production of pheasants under specific conditions. 2. Mating ratio did not significantly affect mortality or pathology of breeding birds. 3. Egg production was significantly higher for the 8:1 mating ratio over the first 5 weeks of the trial but this difference disappeared during the second half of the trial. 4. Incidence of rejected eggs increased as the season progressed, mainly due to poor shell quality, but it was not significantly affected by mating ratio. 5. Fertility of eggs produced from birds under an 8:1 mating ratio was consistently and significantly 4% higher than fertility of eggs from the 12:1 mating ratio. The incidence of eggs showing no sign of mating (no sperm) was twice as high for the 12:1 pens (13.7% of the sample). There was good agreement between macroscopic and microscopic examination of fertility in eggs. Higher fertility in the 8:1 pens appeared to be related to a higher proportion of the females being recruited and mated. 6. Hatchability was significantly improved by adopting an 8:1 mating ratio, presumably due to the higher fertility of the eggs. Candling of the eggs improved hatchability but only for the 12:1 pens probably because more clear eggs were removed from the tray.

Correlation between shell colour and ultrastructure in pheasant eggs.

1. The histochemistry and ultrastructure of pheasant eggs were compared on the basis of blue or brown shell colour. 2. Differences in lectin histochemistry of the outer shell membrane calcification surface indicate a biochemical disruption of the calcification sites in blue eggs. 3. Significant differences were observed in all aspects of eggshell ultrastructure with blue eggs having thinner shells with structural defects. 4. Poor hatchability of blue eggs may reflect high rates of weight loss associated with a defective eggshell.

Observations on the patterns of embryonic mortality over the laying season of pheasants.

1. Embryonic mortality of domestic pheasant (Phasianus colchinus) eggs was recorded for a 10-week laying season for two groups of laying hens maintained under mating ratios of 8:1 and 12:1 (females:males). 2. Mating ratio had no significant effect on embryonic mortality between 1 and 4 or 5 and 20 d but values for these categories doubled as the laying season progressed, both rising to 8% to 9% of fertile eggs. 3. Higher embryonic mortality was observed between 21 and 25 d for the eggs from the 8:1 mating ratio (14.5% of fertile eggs compared with 12.1%) but this was unaffected by week of setting. 4. Reasons for these patterns of embryonic mortality were not clear and further research is needed to determine the factors affecting embryonic mortality in pheasants.

Courtship behaviour of ostriches (Struthio camelus) towards humans under farming conditions in Britain.

1. The courtship behaviour of adult male and female ostriches was observed in the presence and absence of human beings. 2. Courtship behaviours in both males and females were more prevalent in the presence of humans. 3. Exposure to a human for a short period did not stimulate courtship behaviour in the period immediately after the human had withdrawn. 4. Courtship behaviour towards humans may be important in the reproductive success of ostriches in a farming environment.

Morphology of the distal tip of the upper mandible of the ostrich (Struthio camelus) embryo during hatching.

1. The morphology of the distal part of the upper mandible in ostrich embryos was investigated using scanning electron microscopy just prior to and during hatching. 2. Although a keel-like structure on the tip of the upper mandible superficially resembles an egg tooth it appears to play no role during hatching. 3. The distal tip of the upper mandible is covered by an amorphous layer, the right side of which disappears during the hatching process. This layer acts to protect the beak during the rubbing process which creates a hole in the inner shell membrane during hatching.

Feeding and vigilance behaviour of breeding ostriches (Struthio camelus) in a farming environment in Britain.

1. Vigilance and feeding behaviour of male and female adult breeding ostriches were recorded to determine feeding and scanning bout lengths, a time budget and the pattern of vigilance immediately after food was provided. 2. Males were more vigilant and fed for shorter periods than females immediately after concentrate food was delivered but not throughout the whole day. 3. Most interscan periods of males were below 40 s with a maximum of 90 s compared with most interscan periods of females lasting less than 70 s with a maximum of 160 s. 4. Gender differences in behaviour are attributed to increased male vigilance for predators and/or conspecifics, and increased female feeding required for egg production and greater opportunity to feed because of male vigilance.

Feeding and pecking behaviour in ostrich (Struthio camelus) chicks in captivity.

1. Three sets of experiments were performed on two batches of ostrich chicks to investigate the factors affecting the pecking and feeding behaviour of grouped individuals. 2. Chicks showed no significant alteration of their feeding behaviour in response to raising pen walls in the rearing facility from 30 to 60 cm. 3. Further analysis on a different set of birds revealed consistent short term individual differences in the frequency of feeding and non-feeding pecks. 4. There were significant pen effects on behaviour suggesting the possible development of a pen 'culture' of pecking behaviour. 5. Pecking behaviours in 26 to 33 d-old chicks, with the exception of drinking, were generally negatively correlated, so any non-food pecking by a chick was generally associated with fewer pecks targeted at food. 6. By the age of two months chicks were pecking at food on the floor to a far greater extent than at any food presented in food trays.

Plasma thyroxine concentrations in farmed ostriches in relation to age, body weight, and growth hormone.

Thyroid hormones are of interest in ostriches because, in common with other ratites, ostriches are believed to have evolved through neoteny, a process which, in amphibia, is related to thyroid function. Farmed ostriches show marked differences in growth rates, a problem which also could be related to abnormal thyroid function. In adult farmed ostriches (more than 3 years old), mean plasma thyroxine concentration was 1.8 nmol middle dot liter-1 (range 0.2 to 6.5 nmol middle dot liter-1). This is a lower mean and a much greater range than those in adult starlings or Japanese quail measured at the same time. No sex differences were observed. In 5-month-old ostriches (approximately half grown) mean levels were again low (3.1 nmol x liter-1, range 0.2 to 9.9 nmol x liter-1). There was a correlation (P < 0.0005) between thyroxine and body weight, which ranged from 10.8 to 51.5 kg. Growth hormone in this group ranged from 0.7 to 45.6 microg x liter-1, but there was no correlation with body weight or with thyroxine. In the same group of birds at 10 months of age, plasma thyroxine concentrations were similar, but were not correlated with body weight. In young birds sampled between hatch and 13 weeks, mean thyroxine decreased from 7.6 nmol x liter-1 soon after hatching to less than 2 nmol x liter-1 at 2 weeks and remained less than 2 nmol x liter-1 for the following 3 months. Thyroxine was highly variable within and between individuals. There was no correlation with body weight or growth rate. There were no significant differences between values at 13 weeks, 5 months, 10 months, or in adults. The results do not suggest that slow growth is directly related to low thyroxine. However, the low means and wide range of values do suggest that thyroid function in the ostrich is abnormal compared to other birds.

Estimation of the weight and body condition of ostriches (Struthio camelus) from body measurements.

The body dimensions and weights of over 100 ostriches were analysed to investigate which body measurements provided the best estimators of bodyweight. The data were divided between growing and adult birds (below and above two years old) for regression analyses. The residual standard deviation of weight was 0.117 for growing birds, using tibiotarsal length and abdominal girth as predictors. The analogous figure for adults was 0.078 using back length and abdominal girth. An assessment of body condition was made by calculating the average weight-for-size of a bird from skeletal measurements which are unaffected by gross changes in weight, and then comparing it with its estimated or actual weight. These estimates of the weight of a typical ostrich should be useful in veterinary practice, particularly when the weight of a bird is required for the administration of medication.

Time budget and colour preferences (with specific reference to feeding) of ostrich (Struthio camelus) chicks in captivity.

1. Time budget analysis of the typical behaviours of young ostrich chicks showed that chicks spent over 50% of their time foraging and walking. 2. Food presented in bowls was largely ignored whereas food scattered on the floor was readily taken. 3. A colour preference test showed that green was the preferred colour.

Microbial spoilage of ostrich (Struthio camelus) eggs.

1. The incidence of microbial spoilage was investigated in three batches of ostrich eggs, one from Africa and two from Europe. 2. 18% to 21% of eggs in each batch were contaminated with bacteria and fungi, with the latter being found more often in eggs which contained more advanced embryos. 3. Although infertility and prolonged storage reduced hatchability, the high incidence of microbial contamination in ostrich eggs is deemed to be a significant problem. 4. Improving nest hygiene is considered to be the simplest way to reduce microbial spoilage.