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

Conserved in-ovo cranial ossification sequences of extant saurians allow estimation of embryonic dinosaur developmental stages

Dinosaur embryos are among the rarest of fossils, yet they provide a unique window into the palaeobiology of these animals. Estimating the developmental stage of dinosaur embryos is hindered by the lack of a quantitative method for age determination, by the scarcity of material, and by the difficulty in visualizing that material. Here we present the results of a broad inquiry, using 3D reconstructions from X-ray computed tomography data, into cranial ossification sequences in extant saurian taxa and in well-preserved embryos of the early branching sauropodomorph dinosaur Massospondylus carinatus. Our findings support deep-time conservation of cranial ossification sequences in saurians including dinosaurs, allowing us to develop a new method for estimating the relative developmental percentage of embryos from that clade. We also observe null-generation teeth in the Massospondylus carinatus embryos which get resorbed or shed before hatching, similar to those of geckos. These lines of evidence allow us to confidently estimate that the Massospondylus carinatus embryos are only approximately 60% through their incubation period, much younger than previously hypothesized. The overall consistency of our results with those of living saurians indicates that they can be generalized to other extinct members of that lineage, and therefore our method provides an independent means of assessing the developmental stage of extinct, in-ovo saurians.

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.

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.