New Research Suggests Shorter Dry Periods Puts More Milk in the Tank
It's time to question tradition and rethink current advice on the dry period's ideal length in our dairy herds. A recently published study from Florida and other research suggest shorter could well prove better.
Currently, it's recommended that you dry cows off 50 to 60 days before their predicted next calving date. This advice is based on numerous studies that analysed dairy herd improvement records 20 to 30 years ago. These studies showed that cows with dry periods longer than 60 days or shorter than 45 days produced less milk than what was predicted from their previous lactation.
While this is useful information, it's not conclusive proof that cows need 45 days dry. Sorting out why cows had longer or shorter dry periods is impossible because no reasons for chosen dry-off dates were given. Since 50 to 60 days dry was the industry norm at the time, the group outside these limits likely included many cows with problems.
For example, the group that was dry more than 60 days would have included cows dried off early due to new mastitis infections. If these infections persisted they would obviously hurt production in the next lactation. Cows dry less than 45 days included many individuals calving early with twins or having near-term abortions caused by disease-also lowering production.
Modern management advice for feeding during the 60-day dry period includes switching the cow to a low energy, far-off dry-cow diet for 30days, followed by 30 days of a higher energy close-up ration. Three ration changes and three social group changes in this short period may be partly responsible for the lower feed intake reported around calving time. Managing two dry cow groups and two separate diets also adds to the labour and management complexity of the herd.
Perhaps a shorter dry period would make it possible to dry off cows in proper body condition directly into a close up group. Potential nutritional benefits of a single dry cow diet were pointed out in the May 2003 Ruminations column.
A study by M.S. Gulay and co-workers at the University of Florida involved healthy cows at the university that were intentionally given a shorter dry period. The study randomly assigned 84 Holstein cows to one of three treatment groups. One was dried off at 60 days before expected calving date, and was fed a far-off dry cow ration for 30 days, followed by a close-up ration until calving. The other two groups were milked right up to 30 days before calving, and then switched directly to the close-up ration. One of these groups was also given a special drug treatment intended to speed up the changes that take place in the udder at drying off.
In the following lactation, the researchers found, cows with 30-day dry periods had a higher feed intake in the first month of lactation and maintained better body condition scores than cows dry for 60 days. Milk production during the first 10 weeks and over the entire lactation was the same for all groups. However, the additional month of milking at the end of the previous lactation resulted in an extra 510 kilograms of milk per cow for two groups dry for just 30 days.
Three other studies have reported similar results:
Cows do need a dry period. Physiological studies show that the changes the udder goes through to prepare for the next lactation take about three weeks. Yet current advice is that the most appropriate dry period for a modern dairy cow is 45 to 60 days. More recent studies show good reason to question that advice, and suggest dry periods of 30 to 35 days have no detrimental effect on production. Shorter dry periods could, in fact, increase production per lactation.
Is Your Farm a Candidate for Shorter Dry Periods?
We need on-farm experience to assess the merits of shorter dry periods further. If you're thinking about experimenting with this, your herd should meet these criteria:
Where these conditions are met, 35 to 40-day dry periods and a single dry cow group can mean more milk in the tank, higher feed intake in fresh cows and fewer groups to feed and manage in the barn.
Gulay, M.S., M.J. Hayen, K.C. Bachman, T.Belloso, M. Liboni, and H.H. Head, 2003,Milk production and feed intake of Holstein cows given short (30-d) or normal (60-d) dry periods, J. Dairy Sc. 86:2030-2038
Lotan, E. and J.H. Alder, 1976. Observations on the effect of shortening the dry period on milk yield, body weight, and circulating glucose and FFA levels in dairy cows. Tijdschrift Diergeneeskunde 101:77-82
Bachman, K.C., 2002. Milk production of dairy cows treated with estrogen at the onset of a short dry period. J. Dairy Sc. 85:797-803
Grummer, R.R., and R. Rasani, 2003. Dry cow management: can we shorten the dry period? In Proceedings of the Dairy Health Management Certificate Program, 2003 Annual Update Meeting, Ontario Veterinary College, University of Guelph.
This article appeared in the July 2003 Ruminations column of the Ontario Milk Producer magazine
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