Comparative evaluation of abnormal spermatozoa in Pannon White

The connection between sperm cell abnormalities and the breeds and seasons was studied. Semen was obtained from 20 Pannon White (PW), 20 New Zealand White (NZW) and 20 Angora (A) males monthly throughout a year. 697 ejaculates were evaluated. The average abnormal spermatozoa content of the ejaculates was 16.07±1.77, 16.50±0.2I and 27.34±0.30 % respectively. The incidence of head and tail abnormalities was higher than that of other abnormalities in every group, but in A rabbits acrosome abnormalities were also at a significantly high level. The ratio of deformations was higher (P < 0.05) in all seasons in the A breed than in PW or NZW. Under Hungarian climate conditions the summer heat causes both primary and secondary degradation in semen quality. The effect of heat stress on spermatogenesis can be observed in the decreased semen quality in autumn.


Introduction
Comparison ofthe semen quality of different breeds provides useful information from both the theoretical and the practical aspect.The data of different authors are often contradictory to each other.Temperature of 21°C is known as the "comfort zone" for rabbits (FAYEZ et al., 1994).
The rabbit is less tolerant to high temperatures than to low temperatures.If the environmental temperature is above 25-30 °C the behaviour and several physiological parameters change (e.g.: feed consumption, feed conversion, pulse rate, respiration rate).In particular, the respiration rate of Angora rabbits usually increases enormously when the air temperature is above 24 °C for a short period.VIRÄG et al. (1992) investigated the connection between semen quality and different genotypes and also different production and physiological traits.None of the traits (including season) displayed connections with the percentage of abnormal cells, with the exception of genotype.In the ejaculates of Bouscat White and New Zealand White males the incidence of sperm abnormalities was higher in summer compared with other seasons, but there was no difference aecording to breed (AMIN et al., 1987).In contrast to the results of FINZI et al. (1994), unexpectedly, at least some parameters can even improve during acute and chronic heat stress.Season has a significant effect on semen pH and sperm abnormalities of New Zealand White bucks.Semen pH correlated significantly with the percentage both of primary and of secondary sperm abnormalities.Litter size at birth correlated significantly with semen pH and the percentage of abnormal spermatozoa (JARPA-MENDEZ, 1984.)RADNAI et al. (1988) found the following incidence of deformations in Angora rabbits: acrosomal lesions 8.5 %, head deformations 10.8 %, plasma droplets 4.6 % and middle piece abnormalities 0.9 %.Data on 180 Angora rabbit ejaculates were evaluated by CARO et al. (1984).Females were inseminated with the semen.Litter size at birth correlated significantly with the percentage of abnormal spermatozoa.COURTENS et al. (1994) found that pregnancy rate correlated negatively with the frequency of acrosome defects in rabbit semen.The quantitative value and ratio of abnormal forms of spermatozoa is an applicable diagnostic aid for breeders.The objective of the present work was to study the effect of breed and season on the abnormal spermatozoa content of rabbit semen.

2.
Material and method The study to be outlined in this paper was carried out in Kaposvär (Hungary).Housing.The males were aecommodated in individual wire cages.The rabbit house was closed and could be heated in winter (15-16 °C), while the indoor temperature could go up to 25-30 °C during the summer months.The building was aerated by an overpressure Ventilation system providing warm air in winter and some cooling in summer.The illumination was partly natural (through Windows) following daylength, and partly artificial during working hours.Feeding and nutrition.The bucks were fed a commercial Compound feed (crude protein: 17.1%, crude fibre: 13.2%), pelleted in 3 mm pellets and provided ad libitum.The ration also included some hay.Drinking water was available from valve type self-drinkers.The experimental groups.697 ejaculates were obtained from 20 New Zealand White, 20 Pannon White and 20 Angora rabbits.The distribution of the samples was the following: The age ofthe bucks was about 8 months at the beginning ofthe investigation.
Semen collection and evaluation.The semen was obtained monthly by means of artificial vagina.The smear was prepared from the fresh semen on glass slide, then dried at room temperature.The samples were stained with Cerovsky staining (Congo red -gentian violet).The percentage of different deformation types was calculated after the evaluation of 200 spermatozoa per sample.Statistical analysis ofthe results was carried out using Analysis of Variance (ANOVA) to compare the means (STATGRAPHICS, 1991).

Results and Discussion
The morphological characteristics of semen samples have been summarised in Tables 1-3.The yearly average value of total deformation is significantly higher in the Angora bucks than in the Pannon White and New Zealand White ones by 10 % (Table 1).Apart from normally shaped sperm cells the semen samples contained a varying proportion of grossly abnormal and degenerate spermatozoa representing every deviation (Table 2).The percentages of different types of abnormalities are given in the ratio ofthe total cell count.Most of the types of abnormalities showed great individual effect, since the animals responded differently to heat stress (Table 3), this corresponding to the observations of WEITZEetal.(1976).
The incidental rate of acrosome abnormalities was significantly (4-5 times) higher in the Angora group.A considerable difference was found between the ratio of head and tail deformations and that of the other traits, but in the case of New Zealand White a lower rate of tail abnormalities were found.KASA and THWAITES (1992) observed significant increases in the ratio of dead and piriform sperm after an increase in the level of heat stress.
The Pannon White and New Zealand White bucks showed a significantly higher (by 6-10 %) ratio of intact spermatozoa in spring and winter.KADLECIK (1983) found the same tendency in the Russian breed, but in his opinion the percentages of abnormal spermatozoa also depend on the level of inbreeding in the population.The value of deformed cells in the winter ejaculates of the Angora group was significantly low compared with other seasons; however, this was some 4-5 % higher than the highest values in the other groups.
4. Conclusions Our results suggest that Pannon White and New Zealand White males produce less abnormal spermatozoa (about 16 %) throughout the year than Angora bucks (27.3 %).This could be one of the reasons for the unfavourable reproduetive Performance of the Angora breed.The mean values of abnormal cells in the Pannon White and the New Zealand White semen were the same, but the distribution of the main types of spermatozoa ab-normalities were slightly different.Acrosome, head and tail abnormalities showed the highest incidental rate in every group; however, every kind of deformation type was found in the samples.FINZI et al. (1995) developed a method to verify the presence of heat stress in males, based on ratios among different sperm deformations.In our continental climate both the Pannon white and the New Zealand White samples contained about 5-10 % more abnormal sperm cells in summer and autumn than spring, and winter.Under Hungarian climate the summer heat cause both a primary and secondary degradation in sperm.The effect of heat stress on spermatogenesis can be observed in the decreased semen quality in autumn, since after heat exposure (in summer) the effects disappear by the end of the third spermatogenetic cycle (THARWAT et al., 1994), or more than 70 days are required for recovery (BAGLIACCA et al., 1987).The high incidence of deformed cells from spring to autumn in Angora semen and the decreased incidence in winter show that this breed has lower tolerance of heat and/or the Angora almost continuously suffers from heat stress, due to its wool.Shearing had no effect on semen quality either in Angora males (BROCKHAUSEN, 1977) or in New Zealand White rabbits (FINZI et al., 1992).

Table 1
The mean values of deformation rates of spermia in different breeds (x ± s. e.) (Anteil der Spermienanomalien bei den verschiedenen Rassen)

on the same line with different letters ai(
: significantly different (P<0.05).