Development of an automatic bitemeter for grazing cattle

Biting rate in grazing cattle is difficult to record automatically compared with grazing time, ruminating time, or total jaw movements per day. We tested the feasibility of an automatic system for measuring biting rate based on the sound made by severing of the herbage, which is specific to the bite. The portable device described is based on two sensors: a microphone, located beneath the lower jaw, and a mercury switch to determine the inclination of the head, located in a case attached to the neck of the cow. Bites are detected in real time and data are stored in memory every minute before serial transfer to a computer. The bitemeter was validated during 11 sequences for a total of 514 min on Four Holstein dairy cows strip-grazing on vegetative perennial ryegrass (Lolium perenne L.) swards by comparing with visual observations, comparison bring possible each minute. The mean bias between bitemeter and manual recording varied between sequences from -5.8 to +3.1 bites.min(-1) (-12.2 to +7.5%) with an average of -1.6 bites.min(-1) (-3.3%). It was not related to award height. The within-sequence variability of this bias was on average 3.5 bites.min(-1) and was not related to the number of bites.min(-1). It is concluded that the automatic recording of biting rate in grazing cattle is possible with a good degree of precision on the basis of the sound created by severing of the herbage. Nevertheless, additional protection of the microphone and a better standardization of its position would appear necessary for a routine use of the bitemeter in experimental trials. ((C) Elsevier / Inra).