Age at second Improvac((R))-vaccination and its influence on testis weight, testis histology and boar taint compounds of male fatteners compared to entire boars and barrows

作者：Sauer F; Schmoll F; Sattler T^*

来源：Wiener Tierarztliche Monatsschrift, 2014, 101(5-6): 103-109.

• GnRH-vaccination
• pig
• atrophy-degeneration-score
• androstenone
• skatole
• indole

Introduction Vaccination of male fatteners with the gonadotropin-releasing-hormone-analogue Improvac((R)) to avoid boar taint is an alternative to surgical castration and preferable for animal welfare reasons. The abilty to detect vaccinated animals at slaughter is important for the acceptance of the vaccination. The influence of the age of male fatteners at the second vaccination to avoid boar taint on testis weight, testis histology and boar taint compounds was investigated in comparison to the effects on entire boars and surgically castrated pigs. The aim was to test whether testis weight can be used as a criterion to detect animals vaccinated at earlier age at slaughter.
Materials and Methods A total of 289 male fattening pigs were divided into two vaccination groups (IA, n=79, second vaccination at 18 weeks of age; and IB, n=82, second vaccination at 21 weeks of age), one group of entire boars (E, n=88) and one group of barrows (K, n=40). Testis weight was measured with and without epididymis. Histological effects on testis and epididymis were evaluated by means of the atrophy-degeneration score. Levels of androstenone, skatole and indole in back fat were determined and boar taint was tested by the cooking and melting test.
Results Pigs vaccinated at an earlier age (group IA) had lighter testes than pigs vaccinated later (IB). Entire boars had the heaviest testes. However, there were wide individual differences. On histological investigation group IA generally showed testis hypoplasia, whereas the testes of group IB were atrophic. The androstenone concentration in back fat was significantly lower in both vaccination groups and in barrows than in entire boars. Only in entire boars was testis weight and androstenone content found to correlate with boar taint in the cooking and melting test. The levels of skatole and indole correlated in neither group with boar taint.
Conclusions The use of testis weight as the only criterion to detect Improvac((R)) vaccinated pigs at slaughter is not always sufficient because of the wide range of individual differences, which can also be seen in pigs vaccinated at an earlier age. The implementation of an atrophy-degeneration score is useful to assess objectively the influence of Improvac on testis histology. If boar taint is suspected, other tests, such as the cooking and melting test, should be used.

• 出版日期2014