PubMed Health⌕ Search

Biomedical subjects

D E Bernon

Publications and source records attributed to D E Bernon.

9 recordsLinked to original sources
PubMed1989

Influence of selection for egg production and Marek's disease resistance on the incidence of endogenous viral genes in White Leghorns.

The influence of selection on the frequencies of endogenous viral (ev) genes related to the avian leukosis virus was studied in two genetically distinct sets of White Leghorn strains. Each set consisted of four strains: an unselected control strain, two strains selected for egg production traits, and a strain selected for Marek's disease (MD) resistance as well as egg production traits. Eight different ev genes were observed in Set I and seven in Set II, four being common to both sets. Selection for egg production traits resulted in significant changes of the frequency of four ev genes in both sets. In Set I, increased frequencies were observed for ev-4, ev-7, and ev-8; a decreased frequency for ev-9 was observed. The ev-9 gene expresses the viral envelope protein, whereas the others are transcriptionally silent, with the possible exception of ev-7. In Set II, increased frequencies were observed for the transcriptionally silent ev-8 and for ev-15, a gene which consists of a solitary long terminal repeat. Decreased frequencies were observed for ev-18, which codes for infectious endogenous virus, and for a second ev gene of unknown phenotype. In the resistance-selected strains the frequencies of the ev genes were intermediate between those of the control strains and the strains selected for egg production traits with the exception of ev-6, which expresses the viral envelope protein, and ev-3, which expresses internal viral proteins as well as the envelope protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Maternal and sex-linked genetic effects in broiler parent stocks.

Sire and dam populations of chickens were synthesized from commercial broiler parent stocks at the Animal Research Centre, Ottawa. The production of two-way and four-way crosses during synthesis permitted measurement of maternal and sex-linked genetic effects on body weight and conformation traits. Sex-influenced effects were also measured. Reciprocal cross differences were minimal. Consequently, there was no evidence among stocks within parental type of maternal effect differences and only minimal evidence of sex-linked genetic effects. As expected, sex-influenced effects were large. Hence, it appears that breeders must work within strains or stocks to improve maternal and sex-linked genetic effects for body weight and conformation.

Animals↗
PubMed1984

Sexual activity patterns in rams.

Behaviour was measured in reproductively experienced rams from three crossbred strains and two pure breeds (Suffolk and Finnish Landrace) in an attempt to develop a method for rapid screening of sexually aggressive rams and to measure breed differences in sexual activity. A set sequential pattern of activity need not occur in sexually experienced rams, and components of their sexual behaviour may be influenced by the estrual status of the ewe. The data indicate that the number of attempted mounts is an acceptable selection tool, with a mount following a short period of investigation most likely to be followed by coitus. Two sequential ten minute periods are sufficient for rapid screening of rams for short-term sexual activity levels.

Animals↗
PubMed1983

Mating frequency in male Japanese quail: crosses among selected and unselected lines.

The genetics of mating behavior in Japanese quail was investigated in replicated lines selected for high or low number of completed matings and the random bred control which served as the base population for the selected lines. Comparisons involved the parental lines, F1, F2, and backcross generations. Results indicate that mating frequency is influenced by additive and nonadditive genetic variation with the former being the primary heritable influence. The relationships between mating behavior, cloacal gland size, and relative aggressiveness suggest that selection for mating frequency influences factors commonly affecting these traits.

Aggression↗
PubMed1981

Fertility of chickens from lines divergently selected for mating frequency.

Fertility comparisons of males under natural and artificial mating situations were made among lines of chickens selected for high and low mating frequency and the randombred population from which the selected lines originated. Although highly significant differences existed among lines for the frequency of sexual behaviors, there were no significant differences in fertility among lines either when males were with females for extended periods of time or when hens were artificially inseminated. Significant differences were found between mating systems for days to peak and duration of fertility.

Animals↗
PubMed1976

Effect of four lighting regimes on broiler performance, leg abnormalities and plasma corticoid levels.

The effect of four lighting regimes: (1) continuous light (5 to 10 lux); (2) an intermittent system of 1 hr. of light (5 to 10 lux) and 3 hr. of darkness; (3) an intermittent system of 1 hr. of light (5 to 10 lux) and 3 hr. of darkness interrupted by 13 hr. of regular light (5 to 10 lux); (4) as with (3) but with low intensity light (less than 1 lux) during the 13 hr. period while the intermittent system continued, was studied in 2400 broilers of two commercial crosses over two trials. Lighting regime had a significant effect of body weight in trial 2 with birds on treatments 3 and 4 being lighter than those on treatments 1 and 2 which did not differ. Lighting regime had no significant effect on feed to gain ratio, percent crooked toes or mortality to 8 weeks. Birds grown on continuous light had significantly more leg abnormalities than those grown on any of the intermittent regimes. In trial 1 birds grown on continuous light had significantly higher plasma corticoid levels than those grown on any of the intermittent regimes. The same trend existed in trial 2, except that birds on treatment 3 had the highest plasma corticoid level.

Adrenal Cortex Hormones↗
PubMed1975

The activity of some peptide hydrolase enzymes in fresh and stored poultry semen from full sib groups of males and their relationship to fertility.

The seminal plasma and sperm of fresh and stored poultry semen were analyzed for the presence of eight peptide hydrolase enzymes. Five enzymes: carboxypeptidase A, carboxypeptidase B, chymotrypsin, glycylglycylglycine hydrolase and pepsin were not present in either plasma or sperm. An aminopeptidase-like and a cathepsin-like activity were found in seminal plasma and sperm while a trypsin-like activity was found in sperm only. There was a significant difference between full sib groups with respect to aminopeptidase-like activity in fresh and stored plasma, while storage for 24 hours resulted in a significant increase in trypsin-like activity of sperm. The aminopeptidase-like activity of fresh sperm was positively correlated with duration and percent fertility of fresh semen, while neither cathepsin-like activity nor trypsin-like activity were correlated with fertility of fresh or stored semen except for a positive correlation between the cathepsin-like activity of fresh plasma and percent fertility of fresh semen.

Aminopeptidases↗