Disease-induced variability of genetic correlations: ascites in broilers as a case study.

Breeding against a production disease is complicated by multiple relationships between productivity, disease, and environment. Ascites in broilers is such a disease. The combination of the reasonably well understood etiology (a physiological/pathological cascade due to inadequate oxygen supply) and the practical relevance makes ascites a relevant case for demonstrating and partly revealing these complex relationships.

Evaluation of between-line variation for within-line selection against ascites in broilers.

Within-line opportunities for selection against ascites were studied in a data set comprising a 10-line comparison. The study attempted to reveal whether contrasts between lines provide reliable candidate traits for within-line selection. Mortality was chosen as the reference trait.

Direct experimental evidence of slip in hexadecane: solid interfaces.

The boundary condition for the flow velocity of a Newtonian fluid near a solid wall has been probed experimentally with a novel setup using total internal reflection-fluorescence recovery after photobleaching leading to a resolution from the wall of the order of 80 nm. For hexadecane flowing on a hydrocarbon/lyophobic smooth surface, we give what we think to be the first direct experimental evidence of noticeable slip at the wall. We show that the surface roughness and the strength of the fluid-surface interactions both act on wall slip, in antagonist ways.

Fat deposition in a broiler sire strain. 4. Performance of broiler progeny of four differently selected sire lines.

Cocks from four lines selected for a low amount of abdominal fat (AF), a favorable feed conversion ratio (FC), and high body weight after restricted (GR) or ad libitum (GL) feeding were mated to commercial broiler breeder hens. A total of 3,600 broiler progeny in three hatches from these matings was reared by line in litter pens. At 41 days of age GR and GL line progeny had significantly heavier body weights, poorer feed conversion ratio, and higher percentages of abdominal fat than AF and FC line progeny.

Fat deposition in a broiler sire strain. 3. Heritability of and genetic correlations among body weight, abdominal fat, and feed conversion.

Body weight, abdominal fat, and feed conversion were measured in ad libitum-fed pedigreed chickens of four lines selected from a broiler sire strain. Lines were selected for four generations for a low amount of abdominal fat (AF), a favorable feed conversion (FC), a high body weight after restricted feeding (GR), and a high body weight after ad libitum feeding (GL). A total of 2,400 pedigreed chickens from three hatches were reared by line in groups on litter and 864 chickens were tested for individual feed conversion in individual cages.

Selection for sperm quality in White Plymouth rocks.

A selection for sperm quality was carried out in the White Plymouth Rock population of the Spelderholt institute. The percentage of morphologically abnormal spermatozoa was used as the most important selection criterion. The population was selected in two directions, viz.