The effect of the presence of steers on the behaviour of grazing yearling bulls.

A.M. Nicol and A.J. Meikle

Animal and Veterinary Sciences Group, Lincoln University, Canterbury

E-Mail:nicol@lincoln.ac.nz

Proceedings of the New Zealand Society of Animal Production. 1997, 57: 96-99

Elements of the behaviour of sub-adult grazing bulls can lead to physical damage to animals, pastures and farm structures. We tested whether the presence of steers would modulate bull behaviour. In two experiments, 32 fourteen-month-old Friesian bulls (average liveweight 346kg) and 32 Friesian steers (341kg liveweight) in groups of 10 to 32 animals were rotationally grazed on permanent pasture at a stocking rate of 23 cattle/ha for 12 to 16 days. The incidence of agonistic behaviour (mounting, teasing, butting, pushing, displaying) was monitored by continuous recording during two, 3 hour observation periods each day at 2 day intervals.

Experiment 1, in which the ratio of bulls to steers was established at 100:0, 70:30, 30:70, 0:100 by substituting steers for bulls in groups of 16 bulls, showed that the incidence of agonistic behaviour per bull was reduced from 0.83/bull/hour in 100% bulls to 0.62 and 0.49 for 70 and 30% bulls respectively (SEM ± 0.12). Experiment 2, in which the ratio of bulls to steers was established at 100:0, 70:30, 30:70 by the addition of steers to groups of 10 bulls, showed that the incidence of agonistic behaviour per bull was significantly lower, 0.18/bull/hour, at 30% than at 70% bulls (0.62) or 100% bulls (0.41). The incidence of agonistic behaviour of steers was significantly lower (0.13 and 0.07/steer/hour in experiments 1 and 2 respectively) compared with bulls and was not significantly affected by treatment.

Across experiment regression analysis of the incidence of agonistic behaviour on the number of bulls and steers showed that the incidence (/bull/hour) increased by 0.07 (± 0.03) and decreased by 0.06 (± 0.02) per additional bull and steer, respectively. Mixing bulls and steers may be a useful approach to decreasing agonistic interactions between bulls.

Keywords: NZSAPAB;

Last Updated 12-09-1998