PubMed Health⌕ Search

Biomedical subjects

G W Friars

Publications and source records attributed to G W Friars.

13 recordsLinked to original sources
PubMed1992

Development of a selection index to improve market value of cultured Atlantic salmon (Salmo salar).

Genetic parameters were estimated on growth and development traits using analyses of variance and covariance of 42 full-sib families from a select line, 39 full-sib families from a control line of the same strain, and 37 full-sib families from another unselected strain. The traits included percent 1+ smolts, percent sexually immature fish after 1 year in seawater (nongrilse), and fork length measured at intervals throughout the production cycle. The number of fish sampled per family was 30 of 300-1500 for all freshwater traits and 15-60, i.e., all individuals present, for all seawater traits. Heritability estimates of freshwater traits had a broad range (0.15-0.61), but estimates were lower for seawater traits (0.06-0.29). There was a general reduction in heritability estimates for traits measured at increasing ages both in freshwater and seawater. These reductions may in part represent declines of maternal and common environmental effects that inflate heritability estimated from full-sib families. The genetic correlations indicated positive associations between freshwater and seawater growth parameters. However, the correlations decreased with increasing intervals between measurements. A selection index was developed using the estimates of the genetic and phenotypic parameters for three economically important traits: percent 1 + smolts, percent nongrilse, and harvest length. The seawater traits, percent nongrilse, and fork length at 17 months (harvest length) were the most important in the index.

Animals↗
PubMed1979

Considerations of a method of analyzing diallel crosses of atlantic salmon.

Inferences derived from a proposed mixed model analysis of a diallel cross involving four stocks of Atlantic salmon (Salmo salar) are illustrated with growth data on weight and length. Variation between stocks was more apparent when samples represented dams as opposed to sires, thus stressing the relative importance of maternal effects. However, the ranking of stocks was not altered when either the means of sire sources or the means of dam sources were considered. No heterotic effects were found for the growth traits studied.

Analysis of Variance↗
PubMed1969

Frozen turkey semen.

Semen samples from Bronze turkeys, extended with Brown's buffer and antibiotics, and protected with combinations of ethylene glycol-glycerol and N,N-dimethylacetamide-glycerol were frozen at the rate of 8 degrees C per minute down to -196 degrees C. Similar treatments were used as controls. Five White virgin hens were inseminated with semen from each group before and after dialysis. The per cent fertility of the frozen semen samples after dialysis was lower than the corresponding control groups.

Animals↗
PubMed1969

Appraisal of collection techniques and storage temperatures on turkey plasma cholinesterase levels and blood glutathione concentrations.

The effects of different blood collection procedures, various storage temperatures and durations of storage on the levels of plasma cholinesterase and whole blood glutathione in turkeys were investigated. Collection of blood through vacutainers yielded satisfactory results. Whereas the plasma cholinesterase activity remained unchanged even after three weeks of storage at -17.8 degrees C., blood glutathione concentration was unaffected only when the samples were stored at -28.9 degrees C for the three weeks. The range of mean activity was from 4.64 to 4.71 DeltapH/hour x 10 for cholinesterase and from 44.85 to 47.91 mgm/100 ml for glutathione.

Animals↗
PubMed1968

The reproductive tract of the turkey hen (a biometrical study).

A biometrical study of the reproductive tracts of 173 hens was carried out after slaughter at 53 weeks of age. Mean weights and total lengths of the reproductive tracts of four strains of actively laying turkey hens were 265 - 279.5 grams and 80.9 - 84.5 centimetres. Mean measurements in centimetres of oviduct anatomical divisions were: infundibulum 10.9 - 11.7, magnum 44.5 - 45.2, isthmus 12.6 - 14.5, uterus 9.6 - 10.8, and vagina 2.6 - 3.5.

Animals↗
PubMed1968

The effect of season on testicular weight and spermatogenesis in turkeys.

Semen collection was carried out on Large White and Auburn turkeys over a nine month period beginning in February. Equal numbers of each strain were slaughtered periodically throughout the summer and fall. The testicles were recovered, weights recorded, and histological sections were prepared and examined for signs of active spermatogenesis. Significant differences occurred in the testes weight between the two strains studied in the May and September tested birds. Significant differences also occurred in the testes weight within strains between the males slaughtered in May and October. Microscopic examination of histological sections revealed a progressive reduction in active spermatogenesis between testes recovered in early summer and those recovered in the fall.

Animals↗
PubMedDate not supplied

The relationship of right ventricular hypertrophy, right ventricular failure, and ascites to weight gain in broiler and roaster chickens.

Nine hundred twenty-five male progeny from 50 sire families of a commercial sire line were weighed at 14, 28, and 47 days and scored for right ventricular hypertrophydilation at 48 days. Broilers with marked hypertrophy of the right ventricle at processing (298 of 925) were significantly heavier than their more normal contemporaries at 14 and 28 days of age. These results suggest that rapidly growing broilers are more susceptible to increased pulmonary arterial pressure resulting in right ventricular hypertrophy, right ventricular failure, and ascites than slower-growing broilers. Thirty-five (3.5% of 997) broilers died from right ventricular failure and ascites, and 14 (1.5% of 925) has ascites at processing. Two hundred fifty-nine sibs were kept on full feed to 16 weeks of age. Between 7 and 16 weeks, 68 (26.3%) of these cockerels died from right ventricular failure and ascites and a further 27 (10.4%) had marked right ventricular hypertrophy-dilation when processed at 16 weeks. Thus most of the 298 broilers classified as having marked right ventricular hypertrophy at 7 weeks would likely have died from right ventricular failure and ascites if they had been kept on full feed until 16 weeks.

Animals↗