[Early prediction of the magnitude of seasonal variations in testicular diameter and percentage of abnormal spermatozoa in Ile-de-France rams. 1. Animals born in February].

Abstract

The aim of this study, conducted in spring born animals, was to analyse if within a group of males of the same age, there is any relationship between the testis diameters (TD) or between the percentages of morphologically abnormal spermatozoa (AS) recorded in the same animal at two periods of its life (be it at two different spring periods or at two stages of its age: ram lamb and adult). Eighteen Ile-de-France ram lambs born in February 1980 and issued from five adult rams whose seasonal variations in TD and AS had been followed for two consecutive years were used in this study. Semen was collected (artificial vagina, 1 ej/male/wk) from October 1980 until December 1983 (slaughter of the animals) every semester during "Periods" (n = 7). Within a same year, the first semester (February to June) was called "Spring", the second (August to December) "Autumn". AS (150 cells/smear) were controlled on each ejaculate and the same week maximum TD of both testes was measured using a calliper. Correlations were calculated for TD and AS between individual values (simple correlations) or between groups of individual values (multiple or canonic correlations) at different periods. These values were chosen as follows: TD: 4th and 5th control for the first period (P1, ram lamb); the three lowest values recorded in April (P2, P4, P6); the three mean highest values recorded in Autumn (P3, P5, P7). AS: the first five measurements in P1; the four highest percentages obtained in March-April in P2, P4, P6 (correlations were not calculated in autumn since AS were very few). 1 a: On the whole, TD increased with the age of the animal until 24-27 months and passed alternatively by minimal (February to April) and maximal (September) values each year. Testis growth due to the effect of photoperiodism started every year in the first days of June. 1 b: Except alterations of semen quality in August 1983 (due to high local temperatures), AS were always higher in Spring than in Autumn, maximal values being reached in February (P4) or in March-April (P2 and P6). Their seasonal variations were thus opposed to those of TD (r = -0,671 between weekly means of AS and TD of the whole group of animals from P2 to P6). II-TD: Individual TD of ram lambs were significantly correlated with those recorded in the same adult animal (P1-P2, P1-P6, but P1-P4 NS) especially in autumn (P1-P3, P1-P5, P1-P7.