New Zealand Journal of Agricultural Research abstracts

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The effect of bovine somatotropin in a sustained release preparation (Somidobove) on milk production of cows at pasture in New Zealand

S. R. DAVIS

AgResearch
Ruakura Research Centre
Private Bag 3123
Hamilton, New Zealand

B. H. BREIER
P. D. GLUCKMAN

School of Medicine
The University of Auckland
Auckland 1, New Zealand

G. J. BALL

Elanco Products Company
Wharf Road
West Ryde
NSW 2114, Australia

D. G. MOORE

Elanco Animal Health
P.O. Box 97 046
South Auckland Mail Centre
Wiri, New Zealand

K. A. MACDONALD

Dairying Research Corporation
Private Bag 3123
Hamilton, New Zealand

A. M. BRYANT

330 Cambridge Rd
Hamilton, New Zealand

Abstract  Dairy cows in mid lactation were treated with a controlled release preparation of bovine somatotropin (bST; Somidobove) at each of two dose rates (320 or 640 mg). Thirty-six cows per dose rate were treated on four occasions and were compared with 36 control cows (vehicle only). The effect of Somidobove on milk yield was sustained only for the first 14 d of each 28-d treatment cycle. The increase in milk solids output ranged from 188 to 352 g d^-1 over the first 14 d of each treatment cycle, the increase being relatively higher in the 640-mg-dose group. In absolute terms the yield response declined as yield declined with advancing lactation, although the percentage yield response was similar at all stages (mean 18% and 23%, respectively, for 320- and 640-mg-dose groups). Milk fat content was increased and milk protein content was decreased by both Somidobove dose rates. During a period of drought, yield was adversely affected in the 640-mg-dose group relative to control cows. This effect occurred as a carry-over response to treatment. There were no adverse effects of Somidobove treatment on any aspect of animal health, including calf birthweight and calving liveweight. Further work is required to optimise bST dosage levels and patterns and to establish effects of bST on feed intake for grazing dairy cows in New Zealand.

Keywords  bovine somatotropin; milk yield; dairy cows; Somidobove; milk composition

New Zealand Journal of Agricultural Research, 1999, Vol. 42: 315-323

0028-8233/99/4203-0315 $7.00/0 (c) The Royal Society of New Zealand 1999

PDF file of entire paper: medium quality (720K); (scanned from paper original: notes about this process)

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