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Biomedical subjects

D L Pollock

Publications and source records attributed to D L Pollock.

9 recordsLinked to original sources
PubMed1999

A geneticist's perspective from within a broiler primary breeder company.

Recent trends occurring in broiler primary breeding companies are described. The structure and operation of broiler primary breeder companies are described from pedigree elite populations, through great-grandparent and grandparent generations, down to the parent stock. The relatively low value of fertility and hatchability, compared with yield and feed efficiency as selection traits, is assessed. The impact of the last 10 yr of genetic improvement in broiler and breeder traits are quantified and discussed, and predictions for future performance are made. It is concluded that artificial insemination will not be used in broiler primary breeder grandparent flocks or broiler breeder flocks until there is a 20% decline in fertility.

Animal Husbandry↗
PubMed1997

Maximizing yield.

Genetic selection for edible meat yield will intensify as a result of market demands. Phenotypic selection in larger populations using nondestructive lean tissue estimation, more progeny and sibling carcass measurement, inclusion of female lines, and marker assisted selection will provide the means. Transgenics and genetic engineering will be used at the rate consumers accept them. As the kill age of birds decreases and edible meat yield increases, correlated concerns will include meat quality, bird immunocompetence, behavior, and reproduction. Higher yielding birds will be more difficult to manage.

Animals↗
PubMed1979

Pregnancy termination in the control of the tibial hemimelia syndrome in Galloway cattle.

A description is given of the symptoms, frequency and mode of inheritance of a lethal genetic defect in Galloway cattle known as the tibial hemimelia syndrome. Plans for the control of the defect are described, and the role of the Galloway test herd identified. Investigations in the test herd demonstrate that it is possible to detect the tibial hemimelia syndrome characteristics in 90-day-old fetuses and that those fetuses can be regularly and readily obtained undamaged by pregnancy termination using prostaglandin F2 alpha. The role of pregnancy termination in the control of the tibial hemimelia problem is discussed and ideas for its development presented.

Abortion, Induced↗
PubMed1978

The chromosomes of cockerels (Gallus domesticus) during meiosis.

The chromosomes in spermatogenic cells of 10 cockerels were examined. Prior to removing the testes, the birds had been injected with either 2.5 mg vinblastine sulfate or 5 mg colchicine, or were untreated. A cell suspension was made from small pieces of testis and slides were prepared using an air-drying technique. Pretreatments of the birds increased the numbers of spermatogonial and secondary spermatocyte cells at metaphase and rendered them more amenable to analysis. The modal number of macrochromosomes or bivalents was observed in 90.2% of spermatogonia, 98% of primary spermatocytes at diakinesis, and 94.2% of secondary spermatocytes. Polyploid cells at all stages were thought to be largely artifacts of the procedure. Aneuploidy was rare, being found in only 1% of secondary spermatocytes. It is estimated that between 56 and 66 chiasmata occur in the 39 bivalents; of these, an average of 28 are seen in the six macrobivalents. Average numbers were 8.1, 5.9, 4.6, 3.6, 2.4, and 3.5 for macrobivalents 1 through 5 and the Z respectively. The numbers of chiasmata differed significantly among birds but were not differentially affected by pretreatment of the birds.

Animals↗
PubMed1976

The chromosome number of Gallus domesticus.

1. Chromosome counts were made on 105 spermatogonial and diakinesis cells prepared from testicular tissue taken from 10 hybrid cockerels. 2. The modal numbers for the diploid chromosome and haploid chromosome complements were 78 and 39 respectively.

Animals↗