Editor:
Dr. Tom Overton
Assistant Professor of Dairy Management/Nutrition
Department of Animal Science
Cornell University
272 Morrison Hall
Phone:  (607) 255-2878
FAX:  (607) 255-1335
Email:  tro2@cornell.edu

Dietary fat for dry cows

Substantial attention has been paid to inclusion of supplemental fat sources in diets of transition cows during recent years. In an initial experiment designed to determine whether supplemental dietary fat during the dry period would successfully add body condition to thin cows during the dry period, Illinois researchers found that the cows fed the supplemental fat (~ 1.2 lb per day) during the dry period did not accumulate fat in their livers during early lactation (Grum et al., 1996. J. Dairy Sci. 79:1850-1864). Dry matter intakes of cows fed the additional fat were decreased during the dry period compared with cows fed control and high-concentrate diets during the dry period; therefore, the effects of additional fat were confounded by differences in intake among the treatments. These effects on liver fat metabolism were not expected, and stimulated further research to determine whether additional fat in diets for dry cows would indeed benefit liver metabolism.

In order to separate the effects of dietary fat supplementation and intake during the dry period, Burhans and Bell (Proc. 1998 Cornell Nutr. Conference, pp. 247-258) formulated diets to equalize energy intake among treatments and found that there was no difference in plasma nonesterified fatty acid concentrations, liver fat content, or postcalving milk yield between the fat-supplemented diet (~ 0.5 lb per day) and the control. Researchers at the University of Wisconsin (Bertics and Grummer, 1999; J. Dairy Sci. 82:2731-2736) used a feed restriction model to evaluate whether supplemental fat (~ 1 lb per day) would either decrease fat accumulation in liver when nonlactating cows were subjected to feed restriction or increase the rate of fat clearance from liver upon return to ad libitum intake. They found that additional dietary fat actually increased liver triglyceride content in cows subjected to feed restriction and decreased the rate of fat clearance from liver upon return to ad libitum intake. A followup experiment from the University of Illinois involving feed restriction (80% of NRC-predicted requirements) and fat supplementation during the dry period demonstrated small decreases in liver triglyceride content at day 1 postcalving (Douglas et al., 1998. J. Dairy Sci. 81(Suppl. 1):295.

In summary, these data suggest that supplemental dietary fat during the dry period will not prevent triglyceride accumulation in liver during early lactation. Our recommendation is to not include additional fat in the diet of cows during the dry period or during the first 30 days of lactation because of concerns about potentially decreased dry matter intakes of cows fed fat (even though net energy intakes may be similar). However, if the particular management situation that you are working with is committed to having fat in the diet of cows after freshening, then a small amount of fat should also be included in the diet fed to the closeup dry cows to aid with adaptation to the postpartum diet.

T. R. Overton

New look to our publications section!

We have redesigned our publications section to make it more user-friendly! Simply click on the "Articles/Publications" section of our page to see the list of subject headings. The articles under each can be downloaded by clicking on the title of the appropriate article, provided that you have Adobe Acrobat Reader installed on your computer. If you do not have Acrobat Reader installed, click on the icon included on the publications page to download this free software program.

2000 Northeast Dairy Producers Conference

March 6-8, 2000
Rochester Marriott Thruway Hotel
5257 West Henrietta Road
Rochester, NY 14602

For registration information, please contact Dee Brothers at 607-255-4478; fax 607-255-1335 or email:  dab2@cornell.edu

Email notification

Please email Tom Overton at tro2@cornell.edu to be added to our list of subscribers for notification of new issues.