Die Kastration männlicher Lämmer mittels Immunisierung gegen GnRH

Abstract

The objective of this study was to evaluate the effect of a GnRH-vaccine in the ram lamb. Experiments were performed using 20 male lambs, randomly divided into a test (GnRH-immunization) and control group (physiological NaCl-solution). At a body weight of 20 kg (age 2-3 months) and three weeks later, all animals of the test group received 2 ml of Improvac (CSL Limited, Parkville, Victoria, Australia). The body weight as well as the blood testosterone concentration were measured weekly for 16 weeks. Thereafter, blood samples for testosterone analysis were taken monthly in immunized lams only. After the booster injection testicular growth was suppressed and plasma testosterone remained at low values < 0.1 ng/ml for at least 12 weeks. The mean corresponding testosterone concentrations for the control lambs ranged between 0.1 and 0.9 ng/ml plasma. An increase of testosterone was observed in 8 of 10 immunized animals between 3 to 7 months after the booster dose. The control lambs showed a tendency for better growth rate than vaccinated animals, but the difference was not significant. Our results demonstrate that in prepubertal ram lambs two immunizations with Improvac, three weeks apart, can suppress testosterone secretion and testicular growth at least for three months after the booster injection. For a suppression of reproductive function longer than three months after the second vaccination, a third immunization is needed at this time or when testicular growth is beginning.

Vaccination against gonadotropin-releasing factor (GnRF) with Bopriva significantly decreases testicular development, serum testosterone levels and physical activity in pubertal bulls

“…The suppression of reproductive function using an anti-GnRF vaccine has been demonstrated in numerous studies in cattle [3][4][5][6][7][8][9][10][11][12][13], sheep [10,[14][15][16][17][18][19][20][21], pig [22][23][24][25][26][27][28], horse [29][30][31][32][33][34] and in wild animals [35][36][37][38][39].…”

Effect of vaccination against gonadotropin-releasing factor (GnRF) with Bopriva® in the prepubertal bull calf

“…After immunization against GnRF, antibodies neutralize the endogenous GnRF resulting in the suppression of secretion of the gonadotropins LH and FSH in the anterior pituitary. The effectiveness of vaccination against GnRF could be demonstrated in numerous studies in cattle (Aissat et al, 2002;Cook et al, 2000;D'Occhio et al, 2001;Finnerty et al, 1998;Geary et al, 2006;Hoskinson et al, 1990;Jago et al, 1997;Jeffcoate et al, 1982;Neeson and Colson, 2004;Stevens et al, 2005;Theubet et al, 2010), sheep (Brown et al, 1994(Brown et al, , 1995Ferro et al, 2004;Janett et al, 2003Janett et al, , 2009aJeffcoate et al, 1982;Ülker et al, 2005), pig (Bonneau et al, 1994;Clarke et al, 2008;Claus et al, 2007;Dunshea et al, 2001;Fuchs et al, 2009;Jaros et al, 2005;Zamaratskaia et al, 2008), horse (Dalin et al, 2002;Elhay et al, 2007;Imboden et al, 2006;Janett et al, 2009b;Schanbacher and Pratt, 1985;Turkstra et al, 2005) and in wild animals (Curtis et al, 2002;Miller et al, 2000Miller et al, , 2004.…”

“…Regarding reversibility of immunization against GnRF, it has been known that the effects on fertility are individual and may last for a prolonged time (Brown et al, 1994(Brown et al, , 1995Clarke et al, 1998;Janett et al, 2003). Ram lambs immunized twice at an age of 3 to 4 weeks and 13 to 14 weeks against GnRF showed a decreased testicular size when they reached 2 years of age (Brown et al, 1994).…”

Castration of male livestock and the potential of immunocastration to improve animal we

“…Administering two separate doses of 2 mL each, three weeks apart suppressed testosterone secretion and decreased testicular growth for at least three months after the booster vaccination without significant effects on growth in comparison to intact rams (Janett et al, 2003). Improvac ® shows promise in the application of immunocastration in rams to commercial systems; however, the directions of use have been developed for swine and thus warrant further investigation in sheep in order to establish the optimal use.…”

“…Only two studies have investigated the extra-label use of Improvac ® to vaccinate ram lambs (Janett et al, 2003;Needham et al, 2016b). Administering two separate doses of 2 mL each, three weeks apart suppressed testosterone secretion and decreased testicular growth for at least three months after the booster vaccination without significant effects on growth in comparison to intact rams (Janett et al, 2003).…”