Relationship Between Testicular Measurements, Body Weight and Semen Quality in Young Dairy Bulls

Abstract

Dairy bulls, 322 Ayrshires (Ay) and 85 Friesians (Fr), were studied at the age of 11 months. Of the bulls, 286 Ay-bulls and 80 Fr-bulls produced semen of acceptable quality for use in A.I. Scrotal circumference, tonometer measure, scrotal fold thickness, 1-year body weight and testicular palpation were used to predict unsuitable bulls for A.I. Non-return rate was used as a measure of fertility.

Scrotal fold thickness and 1-year weight had no significant correlation with fertility or semen quality. Scrotal circumference had a significant positive correlation with fertility. Tonometer ratio had a significant negative correlation with fertility. Testicular palpation was the best basis for predicting bulls with poor semen quality in this study. Twelve bulls were recorded as having testicles of different sizes, 1 testicle being more than 20 % bigger than the other. Only 2 of these 12 bulls produced semen of acceptable quality. One of these 2 bulls was, after slaughter, diagnosed as having a hereditary testicle disease. Friesians were shown to have significantly higher fertility than Ayrshires.

Sammanfattning

Varken skrotumhudens tjocklek eller tjurens vikt vid 1 års ålder var signifikant korrelerade till fertiliteten. Skrotumsäckens omkrets var signifikant positivi korrelerad till fertiliteten. Tonometervärdet hade en signifikant negativ korrelation till fertiliteten. Palpation av testiklarna var den bästa metoden för att identifiera tjurar med dålig spermakvalitet i denna studie. Tolv tjurar konstaterades ha testiklar av olika storlek, där den större testikeln var mer än 20% större än den mindre. Av dessa 12 tjurar producerade endast 2 sperma av godkänd kvalitet. En av dessa 2 tjurar konstaterades efter slakt att ha en ärftlig testikelsjukdom. Den frisiska rasen visade sig ha en signifikant högre fertilitet än Ayrshire rasen.