Plasma levels of somatotropin, somatostatin and metabolites in dairy cows fed a protected fat enriched diet

Eighteen dairy cows were divided into two groups: group C (control) and group S (calcium soaps). Control concentrate (group C) did not contain exogenous fat, treatment concentrate (group S) contained 6% calcium soaps, replacing amounts of barley, maize and inorganic calcium salts. The trial lasted 50 days; blood samples were taken in the morning before feeding on days 0, 28, 35, 42 and 49. Group S showed significantly higher ,(P<0.01) phospholipid (+31%), total cholesterol (+29%), free cholesterol (+37%), cholesteryl ester (+26%), triglycerid (+33%) and (P<0.05) somatostatin (+23%) plasma levels than group C. The levels of urea (-14%; P<0.05) and the cholesteryl ester: total cholesterol ratio (77.4 vs 78.8%; P<0.01) were lowered by the treatment. Experimental data related to the baseline values (day 0) showed a significant increase in GH (+37%; P < 0.05), N EFA (+24%; P < 0.05) and total protein (+10%; P<0.01) levels in group S. The treatment did not affect plasma levels of glucose, phosphate and the GH:somatostatin ratio.