Chemical and electron microscopic studies of cattle (Bos taurus) with four types of phenotypic pigmentation.

The biological behavior of the pigmentary phenotypes of four breeds of cattle has been analysed: the black pigmentation of Holstein Friesian; the red pigmentation of Limousin; the dilution in Charolais; and the postnatal disappearance of red pigmentation in Chianina. The analytic techniques included the characterization of melanins by high-performance liquid chromatography, the examination of follicular melanocytes by light microscopy, and the examination of melanosomes by electron microscopy. The black phenotype was very strongly eumelanogenic. The red phenotype in Limousin is polymorphic: individual follicular melanocytes contain both mature eumelanosomes and pheomelanosomes. Charolais and Chianina cattle exhibited a dramatic reduction in melanogenic activity, which was characterized by the almost exclusive presence of prephaoemelanosomes in Charolais and of immature premelanosomes in Chianina. In the dilute Charolais phenotype, the density of distribution of follicular melanocytes also seemed to be reduced. The genes that are responsible for these four phenotypes seem to act on the maturation, differentiation, and density of distribution of the melanosomes.

Estimating erosion of phenotypic variation in a French goat population.

A survey was made on a sample of 45 flocks of the goat population in Provence France in 1982. The sample included 56 male goats and 757 breeding females within a 30 km radius of the town of Forcalquier (Alpes-de-Haute-Provence). The visible phenotypic profile was established for the following characters: ear length, ear curling, ear erectness, presence of horns, type of horns, presence of wattles, presence of beard, length of hair, hair coat pigmentation pattern, type of eumelanin in hair, pigment alteration of hair, and white spotting (36 different phenotypes). The visible genic profile is based on 23 various alleles at eight loci. This high degree of genetic variability comes from the traditional local population that is in the process of being upgraded to standardized breeds such as Saanen, Rove and, mainly, Chamois Alpine (95 percent of upgraded flocks). The average coefficient of phenotypic erosion ep had a value of 32 percent among the breeding females in 1982. At the present rate of upgrading the estimate is 90 percent for the male and 85 percent for the female coefficient of genotypic erosion eg by the year 2002. A small nucleus of purely traditional Provence goat (5 percent of the present size of the population: about 1500 goats for the PACA (Provence-Alpes-Côte d'Azur region) will probably have disappeared by that time. Phenotypic and genic profiles of this Provence population have been compared to the profiles of other traditional goat populations in Central Asia, Norway, Sardinia, and Corsica. The available data show profiles that are very similar.(ABSTRACT TRUNCATED AT 250 WORDS)