Histogram of the incidence of limb and tail movements (REW) in the 90 minutes after different rubber ring castration treatments of lambs less than a week of age
Note how the REW incidence during this 90 minute period decreased from 411 after castration and tail docking to 278 for bilateral castration, 194 for unilateral castration and 199 for short scrotum castration, further decreases to 45 were recorded in lambs short scrotum castrated with the benefit of local anaesthesia and only 16 such movements in handled control lambs. Adding the REW incidence for lambs only tail docked (about 131) to the bilateral castrated lambs (278) gave a value about equal to the castrated and tail docked lambs (411). This result suggests that the pain resulting from tail docking and castration is greater than for castration alone, which is not consistent with the findings of Mellor et al 1989b and Lester et al 1991b using plasma cortisol parameters.
The similarity in the values for unilateral and short scrotum castrated lambs could be associated with the source of the pain - in unilateral castrated lambs a visceral organ is damaged - the testes being part of the viscera, but this should not be the case in short scrotum castrated lambs.
