Effects of processing milk on concentrations of glucocorticoids in milk.

Concentrations of glucocorticoids were measured by protein binding in milk subjected to various processing methods. Raw whole milk was collected once per week for 3 wk from bulk milk tanks of each of 10 farms. Nine combinations of processing were tested: 1) none, 2) high-temperature short-time pasteurization of whole milk, 3) high-temperature short-time pasteurization and homogenization of whole milk, 4) bulk pasteurization of whole milk, 5) bulk pasteurization and homogenization of whole milk, 6) high-temperature short-time pasteurization of skim milk, 7) high-temperature short-time pasteurization and homogenization of skim milk, 8) bulk pasteurization of skim milk, and 9) bulk pasteurization and homogenization of skim milk. Mean concentrations of total glucocorticoids ranged from .46 to .65 ng/ml and were not different among either processing methods or whole versus skim milk classifications. No correlations were positive between percentage of fat and concentration of glucocorticoids in whole milk (-.22) or skim milk(-.09).

Glucocorticoids in mammary secretions and blood serum during reproduction and lactation and distributions of glucocorticoids, progesterone, and estrogens in fractions of milk.

Concentrations of glucocorticoids were measured in milk and blood serum during the estrous cycle, prepartum, parturition, postpartum, and early and late lactation. Glucocorticoids in milk did not change during the estrous cycle, averaging .35 ng/ml whereas they averaged .50 ng/ml prepartum, 3.08 ng/ml at parturition, and .50 ng/ml 1 wk postpartum. Glucocorticoids in milk declined from .59 ng/ml to .25 ng/ml as lactation advanced from 1 to 10 mo. Concentrations of glucocorticoids in blood serum were approximately 8 to 10 ng/ml during all reproductive states. There was no positive relationship between percentage of milk fat and concentrations of glucocorticoids in milk. Cortisol was the predominant glucocorticoid in serum; in milk corticosterone concentrations exceeded those of cortisol. Glucocorticoids, being more polar, had higher affinity for the nonlipid portion of milk; in contrast, progesterone, estradiol 17beta, and estrone were located predominantly in the lipid fraction of milk.

Relationship of insulin concentration to blood metabolites in the dairy cow.

Jugular blood samples were taken at regular intervals from 31 ketosis-prone cows from 2 wk prepartum to 7 wk postpartum. Eleven cows exhibited elevated blood ketones and depressed blood glucose indicative of subclinical ketosis. There were no significant differences between means of normal and subclinically-ketotic cows in serum insulin or blood metabolites prior to calving. However, in early lactation, those cows which developed ketosis showed depressed serum insulin, blood glucose, and plasma triglycerides with elevated ketones, acetate in blood, and free fatty acids and cholesterol in plasma. Milk production was also lower in ketotic cows. Correlations within cow between serum insulin and glucose, total ketones, acetate of blood and free fatty acids, triglycerides, and cholesterol in plasma were .014,--.307, .080,--.421, .413, and -.002 for normal cows and .348, -.425, -.324, -.317, .298, and -.131 for subclinically-ketotic cows. It is suggested that low insulin during ketosis is a reflection of depressed blood glucose and, consequently, adipose lipolysis and hepatic ketogenesis are accentuated while acetate utilization and hepatic triglyceride release are depressed.

Blood and liver metabolites in fed and fasted diabetic goats.

Two trials were to study alloxan diabetes in goats. The data were grouped: 1) normal fed goats (10); 2) 48-h fasted goats (5); 3) fed goats sampled 96 h after alloxan treatment (5); and 4) goats treated with alloxan following a 48-h fast and sampled 96 h after alloxan treatment with continued fasting (3). Groups 1 and 4 exhibited the following means: serum insulin 43.9, 16.4, 9.4, and 6.7 muU/ml; blood glucose 55.0, 47.3, 219.6, and 485.6 mg/100 ml; blood ketones 4.3, 2.6, 36.6, and 28.6 mg/100 ml; blood acetate 4.7, 4.0, 42.7, and 4.9 mg/100 ml; plasma-free fatty acids 1.8, 10.0, 14.4, and 40.5 mg/100 ml; and plasma triglyceride 13.3, 7.0, 47.6, and 12.2 mg/100 ml. Liver samples from five fed goats before and 12 days after alloxan treatment exhibited the following means: phospholipid 27.5 and 26.1 mg/g; triglyceride 21.2 and 98.9 mg/g; and percent lipid 7.2 and 14.4. The diabetes was accompanied by fatty liver development and probably reduction in utilization of acetate and triglyceride in the fed animals.