title: Correlation of blood and milk components with the milk yield response to bovine somatotropin in dairy cows.
abstract: 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 4h 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.
authors.affiliation: School of Agriculture, Food and Rural Development, University of Newcastle upon Tyne NE17RU, United Kingdom. mir@aber.ac.uk
authors.forename: M T
authors.initials: MT
authors.lastname: Rose
authors.forename: T E C
authors.initials: TE
authors.lastname: Weekes
authors.forename: P
authors.initials: P
authors.lastname: Rowlinson
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002417:Cattle / Q000097:blood* / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005341:Fibrinolysin / Q000032:analysis; D013006:Growth Hormone / Q000097:blood / Q000494:pharmacology*; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007774:Lactation / Q000187:drug effects*; D008055:Lipids / Q000032:analysis; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis; D010958:Plasminogen / Q000032:analysis
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008055:Lipids; D008894:Milk Proteins; C073294:growth hormone, bovine; D007334:Insulin-Like Growth Factor I; D010958:Plasminogen; D013006:Growth Hormone; D005341:Fibrinolysin; D020155:3-Hydroxybutyric Acid