Behavioral aspects of electronic bull separation and mate allocation in multiple-sire mating paddocks

¹ CSIRO Food Futures Flagship and CSIRO Livestock Industries, FD McMaster Laboratory, Armidale, NSW 2350, Australia
² CSIRO Food Futures Flagship and CSIRO Livestock Industries, JM Rendel Laboratory, Rockhampton QLD 4701, Australia

^* To whom correspondence should be addressed. E-mail: Caroline.Lee{at}csiro.au.

	Abstract

Controlling spatial positioning of cattle through use of electronic collars could provide new ways to farm under extensive conditions. This study examines the potential for bulls to be controlled during mating using electric shocks delivered through radio-controlled collars. Eighteen Belmont Red bulls were fitted with collars containing GPS and able to emit a mild electric shock (500 mW) at the top of the neck behind the poll. Eighteen Belmont Red cows were fitted with GPS collars only. The experiment was replicated 3 times in 3 paddocks. Each paddock contained 2 bulls and 1 cow in induced estrus. On d 1, bulls were either assigned to the cow or not assigned to the cow and on d 2, the assignments were reversed and bulls received the other treatment using a new cow. Treatments were applied for 2 h on each day. The non-assigned bull received an electric shock on approach to either the cow or bull and the assigned bull received an electric shock on approach to the other bull only. The electric shock was applied when animals were within approximately 10 m and moving toward the non-allowed animal. The electric shock was terminated when the animal responded by stopping movement towards the non-allowed animal. In the first 10 min, non-assigned bulls spent less time within 5 m of the cow (P = 0.03) than assigned bulls. Assigned bulls spent more time close to the cow on d 1 than on d 2 during the entire 120 min (P = 0.014). On d 1, assigned bulls moved more toward the cow and non-assigned bull than the assigned bulls on d 2 (P = 0.02). Assigned bulls displayed more sexual behaviors than non-assigned bulls (P = 0.004). Non-assigned bulls were sometimes observed not to approach the cow despite a change in her location. This suggests that the bull associated the electric shock with the cow and not the location in which he received the electric shock. Instances were observed where the cow pursued the non-assigned bull, in which case the bull did not receive an electric shock, and this may reflect cow preference. This study demonstrated that bulls can be separated and prevented from approaching a cow in estrus using an electric shock. However, mate allocation was not completely successful due to cow preference for certain bulls.

Key Words: bull behavior, conditioning, electric shock, electronic collars, multiple-sire mating