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Individual variation in the milk yield response to bovine somatotropin in dairy cows

Lookup NU author(s): Dr Peter Rowlinson

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Abstract

The objective was to relate the short-term milk yield response (MYR) following use of exogenous bovine somatotropin (bST) to changes in plasma concentrations of metabolites and hormones. Twenty-four Holstein cows (52 ± 4.1 d postpartum) received daily subcutaneous injections of saline for 1 wk followed by subcutaneous injections of 33 mg/d of bST for 2 wk (Trial 1). The difference in milk yield between wk 1 and 3 for each cow was used to determine the 5 cows with the highest (HR) and 5 with the lowest responses (LR) to bST. These 10 cows were then used in 3 further trials of the same design (Trials 2, 3, and 4, conducted at 122, 181, and 237 ± 7.6 d postpartum, respectively). Blood samples were taken 2 h after the administration of bST on d 1, 3, 5, 15, 17, and 19 of each trial. The HR group had consistently greater MYR to bST than the LR group throughout their lactation. The LR group had a higher milk yield and lower plasma insulin like growth factor-I (IGF-I) concentrations during the saline treatment in all trials. The increase in plasma somatotropin concentrations following injections of bST was greater for the LR group, whereas the difference in plasma IGF-I level between wk 1 and 3 was greater for the HR group. The HR group had lower levels of 3-hydroxy-butyrate and nonesterified fatty acids before bST treatment. Low short-term response to bST was associated with plasma concentrations of hormones and metabolites that indicate negative energy balance, although other factors may be involved.

Publication metadata

Author(s): Rose MT, Weekes TEC, Rowlinson P

Publication type: Article

Publication status: Published

Journal: Journal of Dairy Science

Year: 2004

Volume: 87

Issue: 7

Pages: 2024-2031

Print publication date: 01/07/2004

ISSN (print): 0022-0302

ISSN (electronic): 1525-3198

Publisher: Elsevier

URL: http://dx.doi.org/10.3168/jds.S0022-0302(04)70020-X

DOI: 10.3168/jds.S0022-0302(04)70020-X

PubMed id: 15328214

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