No abstract

Reduced glutathione (GSH) levels of erythrocytes were determined in five sheep breeds. The Merino breed had a higher incidence of low GSH animals than the other breeds tested. High GSH type animals of the Border Leicester breed had a significantly lower mean GSH level than did higher GSH animals of the other breeds.GSH levels were found to be associated with electrolyte.levels, haemoglobin type, fleece weight, and body weight in Merino sheep.

In domestic sheep there exist two genetically determined types of hemoglobin which have considerably different oxygen affinities. Under most conditions sheep with either of these hemoglobins exist together, apparently sheep with one type being at no gross disadvantage compared to those with the other. Theoretical considerations suggested that the tissues of sheep with the higher oxygen affinity hemoglobin (Hb-A) should be hypoxic relative to those of sheep with the lower oxygen affinity hemoglobin (Hb-B). The data obtained showed that the cardiovascular and respiratory systems of animals with different hemoglobins differed in many respects. It was concluded that the nature of these differences was such that they could be viewed as being due to adjustments by animals with Hb-A to alleviate the potential hypoxia of their tissues relative to the tissues of animals with Hb-B.

SummaryThe influence of haemoglobin type and erythrocyte potassium concentration on oxygen dissociation curves and rate of denaturation of haemoglobin by alkali have been studied in Southdown sheep.A significant difference has been found between haemoglobin types in respect to their oxygen dissociation curves and rate of alkali denaturation.A significant difference was found between the oxygen dissociation curves of high potassium (HK) and low potassiu~ (LK) sheep. No significant difference was found between HK and LK sheep in respect to the rate of denaturation of their haemoglobin by alkali.An association has been found, within a potassium group, between erythrocyte potassium concentration, oxygen dissociation curves, and rate of denaturation of haemoglobin by alkali. The possible significance of the results is discussed.

The genetic control of the level of reduced glutathione (GSH) in the erythrocytes of pure bred Australian Merino sheep has been investigated. The data suggest that the erythrocyte GSH levels are in part controlled by a single pair of autosomal alleles, the gene for GSH-high (OSH a ) being dominant.The data also suggest that the levels of erythrocyte GSH within the GSH-high and GSH-low types are the result of polygenic influences. Heritability estimates of 0-7 and 0-5 within the GSH-high type and 1-2 in the GSH-low type support this suggestion.