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Serum Insulin-like Activity of Normal, Fasting, and Ketotic Cattle^{1, 2, 3,}

Department of Animal and Poultry Science, University of Delaware, Newark

ABSTRACT

The serum insulin-like activity (ILA) of 14 normal, four fasted, and 14 ketotic cows was determined by bioassay, using the uptake of glucose by the rat diaphragm in response to minute quantities of insulin as the assay system.

The mean serum ILA of the normal cows was 1.94 ± .24 mµ of insulin/ml and for the ketotic cows 1.25 ± .23 mµ/ml. This difference is significant at the 0.05 level. Cows fasted for a 72-hr period exhibited an average decrease in serum ILA of 31%. This decrease in serum ILA on fasting indicates that the blood level of insulin is probably a reflection of the altered levels of blood metabolites associated with the fasting and ketotic conditions.

¹ Published as miscellaneous paper No. 413 with the approval of the Director, Delaware Agricultural Experiment Station.

² Supported in part from Regional Funds as a part of Delaware's contributing project to NE-41, Endocrine Factors Affecting Reproduction and Lactation in Dairy Cattle.

³ This paper presents data which comprise a part of an M.S. thesis by the senior author, using methods developed by and presented in an M.S. thesis by the second author, both at the University of Delaware in 1960 and 1959, respectively.

⁴ Present address: Animal Industries Department, University of Connecticut, Storrs.

⁵ Present address: Dairy Department, Pennsylvania State University, University Park.

⁶ Present address: CSESS, U. S. Dept. of Agriculture, Washington 25, D. C.