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Summary.

Dimensional characteristics and proportions of live spermatozoa in permanent nigrosin—eosin preparations from the semen samples of Murrah buffalo bulls were studied in different seasons. Between bulls, all the characteristics varied significantly. Between seasons, all the characteristics, except length of head and mid-piece, varied significantly. Environmental temperature and humidity both appeared to influence the dimensional and enumeration characteristics of the spermatozoa. The percentage of live spermatozoa decreased with increase in air temperature and humidity.

Melanizing activity of rabbit semen was reported by Beatty (1956). The activity—colour reaction when semen is supplied with dihydroxyphenylalanine—varied between males with different pelt colours : black rabbits showed intense melanizing activity and albinos none. It was further observed that the pale colour of semen was a characteristic of dark pelted bucks, and that the colour of the semen was, in some way, related to its melanizing activity. Mukherjee (1964) studied the melanizing activity of the semen of bulls, goats and rams, and observed that the activity varied between animals and between ejaculates from the same animal. Although there was no appreciable relationship between the coat colour of these animals and the melanizing activity of the semen, the yellow semen samples showed stronger melanizing activity than the non-yellow ones. The proportion of 'live' (unstained in eosin-nigrosin) spermatozoa was uniformly less in strongly melanizing semen samples than in weakly melanizing

Summary.

Transplantation of blastocysts from one inbred strain to another and consequent pre- and postnatal development with a different strain as mother has no apparent effect on sperm dimensions.

Summary. The seasons in the 1 year study were classified as rainy, transitional rainy– dry, dry, and transitional dry—rainy. Semen pH and the consistency of the testes did not vary between seasons or among rams. All other characteristics of semen and testis varied between rams. Significant seasonal differences were observed for ejaculate volume, mass, % motility, forward motility score and concentration of spermatozoa, and linear testis measurements. The total number of spermatozoa per ejaculate did not vary seasonally. The magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year.