Skip to main content
ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #223506
Title: Effect of ruminal fill on foraging behavior, intake rate, and plasma ghrelin, serum insulin and glucose levels of cattle grazing a vegetative micro-sward

Author
item Gregorini, Pablo
item Soder, Kathy
item KENSINGER, R - PENN STATE UNIV

Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 4/23/2008
Publication Date: 7/1/2008
Citation: Gregorini, P., Soder, K.J., Kensinger, R.S. 2008. Effect of ruminal fill on foraging behavior, intake rate, and plasma ghrelin, serum insulin and glucose levels of cattle grazing a vegetative micro-sward. Joint Abstracts of the American Dairy Science and Society of Animal Science. Journal of Animal Science. 86(E-Suppl. 2):371.

Interpretive Summary: An interpretive summary is not required.

Technical Abstract: The impact of ruminal fill (RF) on foraging behavior, intake rate and levels of circulating ghrelin, insulin and glucose was measured with four rumen-cannulated lactating dairy cows foraging micro-swards of vegetative orchardgrass. The treatments compared were removal of 1.00 (RF0), 0.66 (RF33), 0.33 (RF66) or 0 (RF100) of total ruminal content. Treatments were randomly applied in a 4 x 4 Latin-square design. Cows were evacuated and re-filled according to treatment at 1200 (treatment setting), then offered the micro-swards at 0200. Micro-swards were weighed before and after foraging sessions. Foraging sessions were time unlimited, but cows were allowed to take a maximum of 15 bites. Herbage was analyzed by canopy strata for chemical composition, toughness and module of elasticity. Eating time, intake rate, total jaw movements, and bite parameters (mass, depth, area and rate) data were collected. Plasma was analyzed for ghrelin and serum for insulin and glucose. Short-term intake rate, bite mass and bite area decreased (P is less than 0.05) while bite depth increased as RF increased. The RF did not affect (P is greater than 0.05) biting rate or total jaw movements. Increasing RF resulted in lower (P is less than 0.05) mean levels of circulating ghrelin, with no changes (P is greater than 0.05) in mean levels of insulin and glucose. However, increasing RF decreased (P is less than 0.05) the incremental change in ghrelin, insulin and glucose levels from the time of treatment setting until the foraging sessions. Little was known regarding bite dimensions and instantaneous herbage intake rate adjustment as a function of RF, or if short-term temporal variations of RF reflect changes in the underlying endocrine physiology. The present study elucidates some of the underlying endocrine physiology under short-term temporal variations of RF and its effect on foraging behavior.