Correlation of blood and milk components with the milk yield response to bovine somatotropin in dairy cows

• Published in: Domestic animal endocrinology Vol. 28; no. 3; pp. 296 - 307
• Main Authors: Rose, M.T., Weekes, T.E.C., Rowlinson, P.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-04-2005
• Subjects: 3-Hydroxybutyric Acid - blood; Animals; blood chemistry; Blood Glucose - analysis; blood plasma; Cattle; Cattle - blood; Cattle - metabolism; dairy cows; Fatty Acids, Nonesterified - blood; Female; Fibrinolysin - analysis; Growth Hormone - blood; Growth Hormone - pharmacology; Holstein; hormones; Insulin - blood; insulin-like growth factor I; Insulin-Like Growth Factor I - analysis; Insulin-like growth factor-1; Lactation - drug effects; Lipids - analysis; metabolites; Milk - chemistry; milk composition; Milk Proteins - analysis; milk yield; physiological response; Plasmin; Plasminogen; Plasminogen - analysis; Somatotropin; Insulin-like growth factor-1; Somatotropin; Plasminogen; Cattle; Plasmin
• ISSN: 0739-7240; 1879-0054
• DOI: 10.1016/j.domaniend.2004.12.001

Our aim was to correlate the individual variation in the milk yield response (MYR) of Holstein dairy cows to bovine somatotropin (bST), with changes in milk plasmin and plasminogen activities as well as with plasma hormone and metabolite levels. Thirty-two housed multiparous Holstein cows (90
±
3.8
days post partum) received daily subcutaneous injections of saline for 1
week followed by subcutaneous injections of 20
mg/day of bST for 2
weeks. Blood samples were taken at approximately 4
h intervals over 24
h at the end of the saline and bST treatment periods. Milk samples were also taken at the end of the saline and bST treatment periods. The difference in milk yield between the saline and the second week of bST treatment (MYR) varied considerably between animals (from −0.2 to +8.6
kg/day, relative to the saline treatment week). Low milk yield before bST treatment was associated with a high MYR. The plasma growth hormone response to treatment was negatively correlated with MYR. Plasma insulin-like growth factor-1 response to treatment was positively correlated with MYR. Furthermore, a high MYR to bST was associated with a lower milk plasminogen level before treatment and a greater reduction in the level of plasminogen in milk following treatment.