Bite Depth Penetration Patterns of Dairy Cows Foraging on Complex Swards

Bite Depth Penetration Patterns of Dairy Cows Foraging on Complex Swards

Sward height was the dominant cue used by dairy cattle to determine the depth of penetration on young vegetative swards. On more complex swards, bite depth penetration was controlled by variations in the depth of regrowth. Evidence showed that cattle grazed to the pseudostem:lamina interface, but sward height exerted a stronger effect on bite depth than pseudostem height. Modelling efforts to predict how the herbivore places bites in space in the vertical dimension across sward states are currently being restricted by the absence of detailed canopy structure descriptions. We argue that the contrast between strata is an important determinant of bite depth penetration through the conditioning effect on biting resistance, and that the “constant proportionality” concept of bite depth control should be treated with caution. Furthermore, we demonstrate that bite depth penetration is continuously being conditioned through information gained on a bite-by-bite basis, and that patch appraisal begins a new cycle at every patch.