Abstract

Two experiments were made to determine if induced cryptorchidism (short-scrotum) would modify behaviour and reduce liveweight loss during the rut without affecting subsequent velvet production. In the first experiment, groups (n = 10) of entire and induced cryptorchid mixed-age stags were used in a behaviour study in consecutive years. In mid-January, stags in the cryptorchid group were sedated with xylazine, and their scrotum shortened as much as possible (two thirds of the length) by the application of two standard lamb castration rings. Behavioural observations made during the rut showed significant (P< 0.05) reductions in the incidence of roaring, chasing and pacing in the cryptorchid group. In a larger scale experiment on six commercial properties, the live weight and condition score change over the rut, and subsequent velvet production was compared on 100 entire and a similar number of cryptorchid stags. Average liveweight loss during the rut (Feb-June) was 17 kg with no significant difference between entire and cryptorchid stags. There was no difference in mean live weight of the two groups the following Sept/Oct and the average velvet weight was 2.48 and 2.41 kg for the entire and cryptorchid stags respectively (P>0.05). Although induced cryptorchidism influenced stag behaviour during the rut, this was not reflected in reduced live weight or condition score loss during this period.

AM, Nicol, and MJ Keeley

Proceedings of the New Zealand Society of Animal Production, Volume 62, Palmerston North, 145-148, 2002