Bite procurement

Interest in the application of engineering principles to the understanding of biological systems such as foraging behavior stems from the knowledge that these principles are embedded in the everyday behavior of animals. Ruminants forage in diverse environments with available forage offering relatively low levels of nutrients per ingested bite. They face considerable challenges in procuring a large number of bites during a 9- to 10-hr day of grazing activity (approximately 30,000 bites for cattle); consequently, the "bite" is considered the building block of daily herbage intake [10,11].

Alternating periods of grazing, rumination, and rest constitute the diurnal activity of a ruminant. During grazing, the location of potential bites while the animal's forelegs are stationary is known as a 'feeding station" [12] and is defined as the semicircular area in front of and to each side of the animal. The establishment of a feeding station implies that one or both of the peripheral senses — sight and smell — have been activated, while the senses of taste and touch influence subsequent behavior following the procurement of initial bites [13]. Procurement of a bite is initiated when the animal lowers its head in search of food. A bite is then removed when a series of manipulative jaw movements (with or without protruding tongue sweeps) gathers herbage, which is gripped by the incisors biting against the dental pad, with forage material effectively running across the incisal edge, allowing for severance to result from the animal jerking its head in a characteristic and timely fashion. On dense foliage or swards of strong phenological contrast, foliage may be lost during the jerking of the head since stiff stems increase the probability that the foliage will spring back, evading the clamping action of the jaws. Furthermore, the bite may necessitate several swinging or jerking motions of the head (i.e., one or more tugs) to sever the bite. The principle of any foraging strategy is dependent upon how the ruminant animal decides where to select bites from, across the habitat as well as from within the sward canopy, and this entails a series of complex mechanisms that have yet to be unraveled.

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