Journal article
Blood plasma concentrations of metabolic hormones and glucose during extended lactation in grazing cows or cows fed a total mixed ration
KK Delany, KL Macmillan, C Grainger, PC Thomson, D Blache, KR Nicholas, MJ Auldist
Journal of Dairy Science | Published : 2010
Abstract
An experiment was conducted to measure the effect of diet on circulating concentrations of metabolic hormones and metabolites in cows undergoing extended lactations. Two groups of 6 Holstein-Friesian cows managed for lactations of 670 d were used in the experiment. One group was fully fed on a total mixed ration (TMR), whereas the other group grazed fresh pasture supplemented with grain (P+G). On 7 occasions between 332 and 612 d in milk, concentrations of metabolic hormones and glucose were measured in the blood plasma of each cow. Cows fed TMR gained more weight and body condition than P+G cows, but did not produce more milk during the study period. Only 3 of the TMR cows continued to lact..
View full abstractGrants
Funding Acknowledgements
The authors are grateful to D. Mapleson, I. Robinson, R. Case, T. Hookey (Department of Primary Industries, Ellinbank, VIC, Australia) and staff at the DPI Ellinbank research farm (Ellibank, VIC, Australia) for technical assistance with cow husbandry, grazing management, and sampling procedures. This work was funded by the Department of Primary Industries, the Geoffrey Gardiner Foundation Ltd. (Melbourne, VIC, Australia), Keenan Pty Ltd. (Bendigo, VIC, Australia), the National Herd Improvement Association (Melbourne, VIC, Australia), the Co-operative Research Centre for Innovative Dairy Products (Southbank, VIC, Australia), and Dairy Australia (Southbank, VIC, Australia). Valuable input into the preparation of this manuscript was provided by L. Marett and P. Moate (Department of Primary Industries, Ellinbank, VIC, Australia).