Blood Pressure and Its Genetic Variation and Co-Variation with Certain Economic Traits in Egg Type Chickens

Abstract

Indirect systolic blood pressures were measured on females of three egg type strains of chickens over five consecutive generations. The measurements were taken between 165-175 days of age. Blood pressure measurements were also taken in one generation on breeder males at 380 days of age. Two of the strains were under selection for egg production traits while the third strain was a control derived from the same genetic base as one of the selected strains. Mean blood pressures were 148 mm. Hg for females and 203 mm. Hg for males. Heritability estimates for females averaged 0.26. Additive type of genetic expression of blood pressure was indicated. Mean blood pressure of birds dying (to 500 days of age) was significantly lower in the control and related selected strain than the mean blood pressure of survivors. In the other selected strain there was no relationship between blood pressure and mortality. A significant interaction was observed between strains and sexes. Genetic and phenotypic correlations with production and egg quality traits were for the most part of a low order of magnitude and relatively few of them statistically significant. The sign of the genetic correlation was positive for body weights and most egg quality traits but negative for egg production and age to first egg.

Avian Physiology

“…In more recent studies, Sturkie (1970a,b) reported no association between blood pressure level and mortality, and this was particularly true when total mortality was low. Hollands and Merritt (1973) have shown higher mortality in some strains with lower than average blood pressure but no relationship in other strains. These results suggested that the differences in viability might be related to general level of mortality and that birds with higher than average blood pressure were better able to withstand greater dis- Blood Pressure ease exposure and physical stresses.…”

“…In that study most of the change was in a hypertensive line and no random line was available for comparison. Hollands and Merritt (1973), who selected chickens for blood pressure in three strains over a 5-year period, reported combined heritabilities of 26-27%. Heart and Circulation: Anatomy, Hemodynamics, Blood Pressure, Blood Flow, and Body Fluids and hypotensive males, respectively, compared to 45 and 33% for the females.…”

Perspectives for Poultry Genetics in the Age of Molecular Biology

“…Genetic parameters have also recently become available for a variety of different traits, e.g. cholesterol content of egg yolk (Cunningham et a/., 1974; Washburn and Nix, 1974;Becker et al, 1975Becker et al, , 1977Nahil eta/., 1977); plasma cholesterol level (Hollands and Merritt, 1973a;Marks and Siegel, 1977;Nahil et al, 1977); egg mass (Jain, 1972); egg yolk and albumen characters (Jain, 1972;Rodda et al, 1977); differences between the sexes in body weight (Ayoub and MCrat, 1973;Ayoub and Magraby, 1975); 4-week body weight in quail at different nutrition levels (Marks, 1973); blood pressure in layers (Hollands and Merritt, 1973b); intra-clutch oviposition interval (Foster, 1972(Foster, , 1973McClung, Wang and Jones, 1975;Yoo, Sheldon and Podger, 1976); ability of quail to utilise lysine (Godfrey, 1968); serum alkaline phosphatase level (Wilcox el al., 1962).…”

“…Marks and Washburn (1977), Washburn and Marks, (1977)-selection for changes in egg yolk cholesterol content; Hollands and Merritt (1973a)-selection for changes in plasma cholesterol level; Godfrey (1968)-selection for lysine utilisation in quail; Hollands and Merritt (1973b)-Blood pressure in selected lines of layers; McClung et al, (1971) and Wilcox (1966)-selection for high level of serum alkaline phosphatase; Lerner and Bird (1948)-selection for resistance to riboflavin deficiency; Siege1 (1972)-selection for high and low mating frequency; Stino and Washburn (1973)-selection for high and low packed erythrocyte volume under adequate and stress environments; Nesheim (1969)-selection for high and low nicotinic acid requirement.…”