Reticular contraction attributes and passage of digesta from the ruminoreticulum in cattle fed roughage diets.
Four nonlactating Holstein dairy cows (BW = 692 +/- 49 kg) were used in a 4 x 4 Latin square design experiment to determine how changes in attributes of reticular contractions were related to changes in passage of digesta from the ruminoreticulum in cattle fed a forage-based diet. Frequencies of reticular contraction during eating, ruminating, and resting phases of the feeding cycle were not affected (P = .09; P = .07; P = .09, respectively) by feeding level. Duration and amplitude of reticular contractions both increased linearly during eating (P = .03; P = .01), ruminating (P = .01; P = .02), and resting (P = .04; P = .02), respectively, as feed intake level increased. After removing the effects of intake, squared partial correlations computed within analyses of covariance indicated that NDF flow was not related to frequency (r2 = .15, P = .20) but was positively correlated with duration (r2 = .76, P = .0001) and amplitude (r2 = .56, P = .003) of contraction, indicating that duration and amplitude of reticular contraction were more associated with duodenal NDF flow than frequency. However, duration of reticular contraction (r2 = .47, P = .014) explained a greater variation in duodenal NDF flow than amplitude (r2 = .011, P = .74). Stepwise multiple regression also indicated that duration of reticular contraction was the attribute most associated (r2 = .76, P = .0001) with duodenal NDF flow. It was concluded that the changes in digesta passage from the ruminoreticulum were associated primarily with changes in the duration of reticular contraction.
Okine
E K
EK
Dept. of Anim. Sci., University of Alberta, Edmonton, Canada.
Mathison
G W
GW
D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004043:Dietary Fiber / Q000378:metabolism*; D004435:Eating; D005260:Female; D005769:Gastrointestinal Motility; D009119:Muscle Contraction; D012044:Regression Analysis; D012159:Reticulum / Q000502:physiology*