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Journal of Dairy Science Vol. 54 No. 12 1835-1839
© 1971 by American Dairy Science Association ®
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Diurnal Variations in Blood and Rumen Metabolites and Feeding Activity of Dairy Steers Under Controlled Lighting1

L. E. Chase2, A. H. Rakes, A. C. Linnerud and J. D. Pettyjohn

Departments of Animal Science and Statistics, North Carolina State University, Raleigh 27607

ABSTRACT

Photographic evidence of diurnal eating patterns of five steers allowed free access to hay in an environment free of natural light were recorded during 37, 24-hour periods preceded by a 14-day preliminary period. Four replicate collections of rumen liquor, jugular blood, and carotid blood were obtained at 2-hour intervals. Rumen liquor samples were analyzed for acetic, propionie, and butyric acid concentrations as well as for pH. Blood samples were analyzed for volatile fatty acids, reducing substances, and ketones. The greatest concentration of eating activity occurred during two periods peaking at 0600 and 1630 hours. Smaller peaks were noted at 0930 and 1430 hours. Only rumen pH and jugular ß-hydroxybutyrate were significantly correlated (.476 and –.243) with eating activity. Generally, the steers stopped eating before detectable rises in metabolite concentration. However, periods of maximum metabolite concentration were associated with periods of relatively little eating. These data do not preclude metabolite Concentration as a factor in the regulation of ruminant feed intake patterns.

FOOTNOTES

1 Paper 3411 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh.

2 Present address: Department of Animal Science, Pennsylvania State University, University Park 16802.






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Copyright © 1971 by the American Dairy Science Association ®.