Meeting Abstract
90.2 Thursday, Jan. 7 The mechanical loading environment of the jaw during ingestive and rumination chewing in goats WILLIAMS, S.H.*; SIDOTE, J.; STOVER, K.K.; DAVIS, J.S.; Ohio University, Athens; Ohio University, Athens; College of Charleston, Charleston; Ohio University, Athens willias7@ohio.edu
Chewing mechanically breaks down food to facilitate chemical digestion in and passage through the digestive tract. In ruminants, ingestive chewing occurs upon initial food intake during feeding. Rumination chewing follows a prolonged period of microbial digestion in the rumen and subsequent regurgitation. Combined, ingestive and rumination chewing result in as many as 60,000 chewing cycles per day in domesticated species. Here, we compare the mechanical loading environment of the jaw during ingestive and rumination chewing in goats. Strains along the mandible during ingestive and rumination chewing were recorded using rosette strain gauges. The magnitude and orientation of principal strains, shear strain magnitude, the number of chews per sequence and chewing cycle duration during both behaviors were determined. Strain patterns, including the relative amounts of principal tension and compression on the working and balancing sides, do not differ considerably between ingestive and rumination chewing. However, absolute strain magnitudes during rumination chewing are as much as 200 microstrain higher than during ingestive chewing. When compared to rumination chewing, chewing-side shifts are more common within a sequence of ingestive chewing. Chewing cycle length does not differ markedly between ingestive and rumination chewing. During ingestive chewing, however, chewing sequence length is generally shorter and the number of chews per sequence is more variable. Thus, rumination chewing involves higher and more rhythmic loading of the mandible as compared to ingestive chewing. These data have implications for understanding the influence of chewing loading patterns on jaw form in ruminating artiodactyls.
