INTERBREED DIFFERENCES IN SEASONAL-VARIATIONS OF SPERMATOLOGICAL PARAMETERS OF BOARS INCLUDED IN AI

Variations of yearly sperm production were investigated on the basis of records of boar ejaculate collections at an A.I. station. A total of 6,370 ejaculates were evaluated coming from 47 adult boars (five boars of the Large White breed - LW, 13 of the Landrace breed - L, 12 of the Duroc breed - D, and 17 hybrid boars - Belgian Landrace x Duroc - BL x D). These parameters were evaluated for three years (1990 - 1992): semen volume (ml), sperm concentration (thous./mm3), spermatozoon motility (%), percentage of spermatozoon defects and total counts of spermatozoa in semen (bil.). A linear model equation was used for statistical processing, so it was possible to eliminate the effects of month, year, collection frequency, breed, sire and breed x site interaction. A balanced course of semen volume variations was observed in the boars of Duroc breed (Fig. 1), in which the average values were decreasing from the beginning of the year to summer, and then they were increasing to the winter period. The boars of Landrace breed and hybrid boars LW x D had the higher values of semen volume in the autumn and winter months (Fig. 1), then these values decreased in the winter-spring period while an increase occurred in late spring followed by a drop in summer and a new increase in autumn. The boars of LW breed showed the least balanced variations of semen volume. Fig. 2 shows that the yearly fluctuations of sperm concentrations were irregular in all groups of boars. The variations of yearly spermatozoon motility were not very large (Fig. 3). Fig. 4 shows the variations of the percentage of spermatozoon defects in the different breeds and hybrid boars. This parameter showed the worst values in the second half of the year. Fig. 5 illustrates the total counts of spermatozoa. The course of these counts in hybrid boars is as follows: an increase in January, a decrease in February, followed by an increase in the spring months and a decrease in summer, and an increase in autumn. A significant decrease occurred in February and September in the boars of the other breeds, while in autumn, particularly in November, an increase in the spermatozoon counts was observed.