INTERRELATIONSHIPS BETWEEN HEALTH ENVIRONMENT AND GENETIC AND PHENOTYPIC PERFORMANCE OF PIGS FOR GROWTH RATE AND BACKFAT

Publisher Website
Google Scholar
Abstract
Data from the Canadian Swine Genetic Evaluation Program for Yorkshire and Landrace pigs born between July 1982 and December 1984 were used to compare herds of different health classification (basic, good and excellent) for environmental and genetic levels and annual rates of environmental and genetic change in days and backfat thickness to 90 kg. There were 35 basic, 34 good and 20 excellent herds represented. Environmental differences between excellent and basic herds were −7.2 ± 3.0 d and 0.72 ± 0.31 mm backfat and between excellent and good herds were −5.3 ± 3.0 d and 0.87 ± 0.31 mm backfat. Faster growth rate in the excellent environment was accompanied by increased fatness. Genetic differences between excellent and basic herds were 1.2 ± 0.4 d and −0.45 ± 0.12 mm backfat and between excellent and good herds were 0.1 ± 0.4 d and −0.30 ± 0.12 mm backfat. Selection differentials were greatest for backfat and least for days in excellent herds and vice versa in basic herds. Rates of genetic change in days to 90 kg were equal across health classification, but excellent herds had greater rates of genetic improvement in backfat than basic or good herds. Data were also obtained from the New Hamburg, Ontario test station on boars that completed performance test between 1984 and 1985. Health classification of herd of origin had no effect on performance of boars for average daily gain or feed conversion at the test station. Effects of health classification of herd of origin on backfat were significant (P < 0.05), but reflected genetic differences between these types of herds rather than carry over environmental effects. However, the percentage that failed to complete the station test was 11.5 for boars from excellent herds, compared to 9.9 and 8.1 for boars from basic and good herds, respectively (P < 0.10). Key words: Health environment, genetic level, test station, backfat, growth rate, selection