Lactic Acid, Pyruvic Acid, Amino Acids, Acetone Bodies, Oxygen, Carbon Dioxide, and Hemoglobin in Arterial and Mammary Venous Bloods of Cows under Various Physiological Conditions

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Abstract
Analyses were made on simultaneously drawn arterial and mammary venous bloods of lactating, nonlactating, fasted and fish-oil fed cows under normal conditions and while under nembutal anesthesia. Fish oil was fed in sufficient amounts and over a sufficiently long period of time to depress markedly both the % fat in the milk and the Reichert-Meissl value of the milk fat. With a few exceptions the bloods were drawn after the cows had been under anesthesia for 30[long dash]320 min. and when the respiration rate was normal. 22 R.Q.''s on lactating anesthetized cows averaged 1.27. 3 R.Q.''s on an anesthetized cow fasted 10 hrs. averaged 0.88 and three R.Q.''s on an anesthetized-nonlactating nonpregnant cow averaged 0.61. 15 R.Q.''s on lactating unanesthetized cows fed fish oil averaged 1.16 and 7 R.Q.''s on lactating, anesthetized cows fed fish oil averaged 1.31. It is concluded that the failure of the R. Q. of the glands of cows fed fish oil to parallel the low R. Q. reported for the fasted cow leaves the interpretation of the latter in doubt. The mean arteriovenous difference for lactic acid in 22 expts. was only 0.18 mg. % and for pyruvic acid in 26 expts. 0.047 mg. %. Consequently these 2 blood substances appear to be of little significance in the metabolism of the gland. Neither the utilization of amino acids nor acetone bodies were altered markedly by depressing the lower fatty acids of milk fat. Arteriovenous Hb differences on anesthetized cows confirm earlier observations that little or no arteriovenous change occurs in unagitated cows, the mean Hb difference being only 0.4%.