Keys To Milk Quality
Introduction
Part1 of the Dry Period series provided an overview of National Mastitis Council
(NMC) recommendations on best practices for a low level of mastitis cases over
the dry period and shortly after calving. The next few articles provide new
ideas and the nuts and bolts of how to plan for and make it happen. This
article focuses on management practices during the weeks leading up to Dry-Off.
Research on whether milk production level at Dry-Off matters, and whether
sudden stop to milking (abrupt), or slow-down to stop milking (intermittent), is
the better approach to meet mastitis and cow comfort goals.‘Old’ Research on Dry-Off Methods
A few studies in the 1950s through 1980s looked to see if milk production level of cows at dry-off was important to new mastitis infections seen at the start of the next lactation. The later studies looked at abrupt Dry-Off only, abrupt Dry-Off combined with decreasing energy in the feed (medium quality hay fed only), reduced milking frequency from 2-times-per day milking (2x-milking) to 1-time-per day milking (1x-milking) only, and reduced feed energy and 1x-milking combination.
Researchers found that production may be important and that the combination of feeding medium quality hay only plus reducing milking frequency to 1x-milking over the last week of milking appeared best. Use of combined practices, intermittent milking plus reduced energy intake led to significantly lower milk production at Dry-Off and fewer new mastitis infections at the start of the next lactation. Cause and effect was not proven. In other words, the drop in milk production was not proven to be responsible for fewer new infections at next lactation.
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University of Tennessee researchers, Oliver and co-workers, also looked to see if concentration of bacteria-fighting compounds were higher in milk of cows with reduced production at Dry-Off. Concentration of the immunoglobulin, IgG; Lactoferrin, a compound that limits iron use by coliform bacteria; and somatic cells, were highest at Dry-Off in cows Dried-Off with combined practices of low-energy-diet, and 1x-milking. This finding provided a possible biologic reason for the practical result and a probable cause.
By reducing milk produced at Dry-Off, concentration of bacteria-fighting compounds in the udder appears to be increased and may directly lead to fewer new infections during the early dry period. Given that all other practices are good to excellent over the entire dry period and early lactation (kept excellent or controlled in the research), lower milk production at Dry-Off may lead to low new mastitis infections after calving.
Other factors that may also be involved, such as inability of teat ends to close due to milk pressure in the udder, reduced cow immune response due to physical stress were not studied, so no additional conclusions could be made on whether other factors, also played a combined role in reducing new infections in the early dry period.
New Research in Process
Based on this research before 1990, the NMC dry cow therapy fact sheet was revised to indicate some of these findings (See: http://nmconline.org/drycow.htm). Specific NMC recommendations at Dry-Off include the following:
- Concentrate feeding of high producing cows should be stopped two weeks before the anticipated Dry-Off date to reduce daily milk yield (target milk yield: less than 35 lbs.-per-day)
- A change in environment can also help reduce production
- Abrupt end to milking is recommended when the target daily yield is achieved (less than 35 lbs.-per-day)
- Intermittent milking along with a decrease in energy concentration of the ration can be used to achieve target yield
Use of the cut-off or threshold of 35-pounds of milk to make the decision on whether to use abrupt vs. intermittent Dry-Off seems arbitrary and reasons for the recommendation are not known. Because cows, facilities, and management practices continually change, and controlled studies have not been done on commercial dairies, more detailed studies over a variety of current on-farm situations are needed.
In addition, no research until recently looked at the impact of abrupt compared with intermittent Dry-Off from a cow comfort and animal well-being perspective. No one has evaluated economics of practices, (e.g., regrouping cows, labor costs, error in procedures, etc.) to determine if benefit is worth added costs of intermittent compared with abrupt Dry-Off.
A group of researchers at Ohio State Department of Veterinary Preventive Medicine, led by Rajala-Schultz are currently looking at Dry-Off methods from a mastitis control and animal well-being standpoint. The studies are funded by USDA and will not be finished for another few years. However, there is some great data from reported research that support previous work and further suggest intermittent milking before Dry-Off may be best.
Article Highlights:
- Milk production at Dry-Off probably affects new mastitis infection risk in early dry period leading to new infections in next lactation
- Lower milk production appears to be better to reduce new infections and is partially due to higher concentration of immunoglobulin, IgG; higher Lactoferrin, and higher somatic cell levels
- To date, there is limited research to give an exact milk production cut-off (e.g., 35 lbs.) for decision to use abrupt vs. intermittent Dry-Off
- Dry-Off Method is currently being studied at Ohio State University to further understand if method used affects new mastitis in the early dry period or cow comfort
- Part 3 in the Dry Period series will provide more evidence suggesting intermittent Dry-Off may be better than abrupt Dry-Off
Dr.Sandy Costello is owner and mastitis/milk quality specialist at Milk Quality Pays and provides on-farm milk quality consulting, training, and product and applied research to aid producer decisions. The mission of Milk Quality Pays is to ensure clients produce and sell milk of the highest quality while maximizing profitability from milk income and maximizing customer assurance of product quality, safety, and worker & animal well-being. Dr. Costello can be reached at 570-768-6140 or scostello@milkqualitypays.com.
