[Relationship between the genetic polymorphism of alkaline phosphatase and the resistance of broiler poultry to Marek's disease virus]. / Zavisimost mezhdu genetichniia polimorfizum na alkalnata fosfataza i ustoichivostta na ptitsite broilerno napravlenie kum virusa na bolestta na Marek.

Studied was the polymorphism of alkaline phosphatase in blood plasma samples taken from 507 poulets and cocks of lines 66 and 77 of the Cornish breed, and lines 88 and 99 of the White Plymouth Rock breed. The birds were divided into three groups to test their resistance to Marek's disease: (1) controls, (2) infected with the virus of Marek's disease with 3 subgroups--resistant birds, slightly susceptible ones, and strongly susceptible ones, and (3) contacts, with two subgroups--survivals and birds that died. The blood plasma alkaline phosphatase was determined through horizontal electrophoresis on a starch gel, employing the method of Gahne. It was found that the alkaline phosphatase genetype FF frequency was lower with lines 66 and 77 than with line 88 and especially with line 99 of the White Plymouth Rock breed which proved most susceptible to the virus of Marek's disease. In the homozygotic alkaline phosphatase genetype SS none of the investigated lines showed any mortality. The resistance of broiler birds to Marek's disease was governed by the Akps allele, while the susceptibility was governed by the Akpf one. The former could be used as a genetic marker in the selection of initial lines of broiler birds by resistance, and the latter could be used as a marker in the selection by susceptibility.

[Resistance of broilers to Marek's disease virus]. / Ustoichivost na ptitsite broileri kum virusa na Marekovata bolest.

Studied was the resistance, resp., susceptibility of the initial broiler lines - 66 and 77 of the Cornish breed, and 88 and 99 of the Plymouth Rhock breed, which are used in this country for the production of the four-line hybrid, - to the virus of the Marek's disease, isolate CT-1. A biologic assay was carried out with a total of 2080 young birds divided into three groups; I groups - infected abdominally; II group - contacts; and III group - controls. Certain breed, line, and sex differences were established in terms of resistance, resp., susceptibility of the investigated birds to the CT-1 isolate of the Marek's disease virus. More resistant were the birds of the Cornish breed as compared to those of the White Plymouth Rhock breed. A rising trend was observed in the resistance of cockerels in comparison with the poults of the respective line. Most susceptible to Marek's disease proved the birds of line 99, especially the poults that were currently used for the production of the mother parental form of the four-line hybrid. The birds with abdominal infection showed death cases as early as the second month of age, mortality rising up to end of the fourth month, while with the contacts and controls most death cases were observed at the fifth month of age. Essential decrease in mortality set in with all three groups after the birds reached six months of age. At a low rate of infections which was experimented with the contact and the control group there were not opportunities to fully discover the resistance of birds to Marek's disease.