Genetic and phenotypic relationships between adipose tissue characteristics of 253 piglets aged 8 d and qualitative characteristics of their backfat at 95 and 145 kg live weight were studied. Heritability of these qualitative aspects was estimated as well. Backfat samples were tested for cellularity, moisture, lipid content and fatty acid composition of the outer and inner layers. Adipose cellularity at birth proved to be correlated with cell volume, moisture and total unsaturated fatty acid, C18:0 and C18:2 contents present in backfat at slaughter. Estimates of heritability calculated for the outer layer of backfat indicated that progress can be made by selecting for water content and fatty acid composition. Neonatal cellularity furnishes a useful indicator not only of the backfat cell size at slaughter but also of the chemical factors important in determining the physical and organoleptic characteristics of porcine fat.

This work was set up to investigate the possible presence of peripheral nervous system involvement as a long-term effect of the exposure to dioxin in 152 subjects with chloracne from the Seveso area; 123 age- and sex-matched subjects living in nearby towns with similar environmental pollution formed the control group. The accident in Seveso took place in July, 1976, and this study was carried out from October, 1982, to May, 1983. Although a peripheral neuropathy was not found in any of the subjects, a significant increase of the number of individuals presenting at least two bilateral clinical signs (p < 0.05) or one abnormal electrophysiological parameter (p < 0.02) was found in the Seveso group. Principal component analysis did not show any subdivision between these two groups. The Fisher approach to discriminant analysis reveals a clear subdivision between the group of the most exposed subjects and randomly selected subgroups of control subjects. In conclusion, clinical and electrophysiological signs of peripheral nervous system involvement occur with a statistically increased frequency in the Seveso population 6 years after the accident, although a peripheral neuropathy was not evident in any of the chloracne patients using the World Health Organization diagnostic criteria.

Backfat thickness, carcass length, area of M. longissimus and carcass composition were determined for 253 Large White barrows and gilts to examine the genetic influence on the main characteristics of the carcass and the correlation of these traits with body measurements and fat characteristics at 8 d of age. Pigs were born to 32 sows mated to the same boar. At the age of 8 d, weight, body length and backfat thickness and cellularity were measured. Pigs were slaughtered at 95 and 145 kg live weight. Heritability and genetic correlations were estimated with dam component of variance. Higher adiposity of carcasses was noted for barrows than for gilts and for those animals slaughtered at the heavier vs at the lighter weight. High h2 values were observed for carcass length (.89 +/- .29), area of the M. longissimus (.67 +/- .26) and backfat thickness at the gluteus medius (.77 +/- .28). Percentage of commercial cuts also had high heritabilities. Phenotypic and genetic correlations between the characteristics at 8 d and backfat thickness, carcass length and M. longissimus area at slaughter were not statistically significant. However, significant phenotypic correlations were found between cellularity of the outer and inner layers at 8 d and percentage of major cuts (e.g., rp = .27 with total fat cuts); cellularity of the outer layer at 8 d also was correlated genetically with carcass composition (e.g., rg = .50 +/- .19 with total fat cuts). Genetic predisposition toward intensive fat deposition was more clearly predicted by cellularity than by thickness of adipose tissue in newborn pigs.

The genetic influence on body and adipose tissue characteristics of newborn pigs and their correlations to growth rate, BW, body length, backfat thickness and adipocyte size in the outer and inner layers of backfat in 8-d-old Large White piglets were determined. Samples of adipose tissue were obtained by biopsy. Pigs were born to 32 sows mated with the same boar. Heritability and genetic correlations were estimated with dam component of variance; therefore, bias due to common environmental effects cannot be excluded. The heritability estimate for adipocyte volume (.89 +/- .28) was higher than that for backfat thickness at the first and last thoracic vertebrae (.50 +/- .22; .63 +/- .24) and for body weight (.59 +/- .23) at 8 d. Backfat thickness was more closely related genetically and phenotypically to body weight and length than to adipose tissue cellularity. Heritability estimates were .75 +/- .28 for gain from 8 d to weaning and from weaning to 95 d (probably because of common environmental effects) but were .31 +/- .20 for ADG from 95 d to slaughter. Characteristics at 8 d were closely correlated phenotypically with growth rate until weaning. These correlations became lower in the two subsequent periods (to 95 d and to slaughter). Corresponding genetic correlations were nonsignificant.