ESTIMATED GENETIC PARAMETERS OF CERTAIN BLOOD CONSTITUENTS AND ECONOMIC TRAITS OF TURKEYS
Levels of plasma cholinesterase and blood glutathione were assayed at 13 and 26 weeks and three subsequent ages of the male and female breeders in two random bred control strains of turkeys and in the respective strains selected for 12-week body weight. The significant differences (P < 0.01) in plasma cholinesterase activity of the selected over the controls ranged from 0.020 ± 0.008 to 0.080 ± 0.005 ΔpH/hour and for glutathione from 2.80 ± 0.32 to 11.10 ± 0.62 mgm/100 ml. at 13 weeks of age. These differences tended to decrease for the measurements made at later ages and in certain cases during the reproductive phases control lines exhibited higher activity than the selected lines.Heritability estimates obtained by midparent-progeny regression in the four strains ranged from 0.15 ± 0.08 to 0.75 ± 0.28 for plasma cholinesterase activity. The estimates for blood glutathione levels in the control and selected strains of the Large White population ranged from 0.02 ± 0.07 to 0.20 ± 0.14 while negative estimates were obtained in both the Auburn lines.There were indications that a significant (P < 0.05) positive phenotypic correlation and a high positive genetic correlation exist between 12-week body weight and the levels of cholinesterase or glutathione at 13 weeks. Apart from this relationship, no significant (P < 0.05) associations were found between the levels of cholinesterase and glutathione at different ages and growth after 12 weeks of age or between the biochemical components and reproductive traits.