Barns & Equipment

This is the time of year to get serious about heat abatement strategies for your herd. Though we enjoy the warmer weather, most lactating cows perform best at temperatures from 40 to 65°F. Signs of heat stress start to occur at around 75°F. This spring, once you’ve installed your new fans and sprinkler systems and cleaned off your existing fans in the lactating herd, you also need to consider making sure your close-up dry cows are kept cool.

Author’s note: The instructions for use of the recommended insecticides are not as comprehensive as the pesticide labels and are intended to be used as guidelines only. Before using any pesticide, read the label for more specific instructions. Many insecticides are sold under brand names not listed in this publication.

House fly and stable fly control on dairy farms

Lameness is an important disorder affecting dairy cows in the U.S., not only for economic reasons, but also from an animal welfare point of view. Prevalence of lameness in the U.S. has increased in recent years.

We conducted a field study in 50 Minnesota dairy herds (and 5,626 Holstein cows) and found the average prevalence of lameness in those herds was 24.6 percent. Lameness status was evaluated by using a 1-to-5 scale locomotion scoring system, with cows scoring 3 or greater considered lame. Our goal in this study was to collect a lot of information from these herds to evaluate what could be potential risk factors for lameness. Farms were randomly selected, without any previous knowledge of lameness status of the herd and without any enrollment criteria besides cows being housed in freestalls. In a field study, we are looking at a whole system in the “real world.” Data of this kind are needed in order to better understand dairy systems, but they can be difficult to interpret.

The effects of heat stress on animal production are well known and have been investigated and documented for a number of years. It is commonly accepted that a temperature humidity index (THI) greater than or equal to 72 creates a stressful environment for lactating dairy cattle. The basic thermoregulatory strategy of a dairy cow is to maintain a core body temperature higher than ambient temperature to allow heat to flow out from the core via four basic routes of heat exchange (conduction, convection, radiation and evaporation).

Editor’s note: The following material is sourced from writings by Dr. Nigel Cook. An extended version of this information is called “Footbath alternatives” and is available at www.vetmed.wisc.edu/dms/fapm/fapmtools/lameness.htm

Footbaths are used as a tool to assist in control of infectious diseases of the claw and interdigital area of the foot. Foot rot and hairy heel warts are the main infectious diseases of the foot, and each respond only partially to footbath use. Both diseases are directly related to the level of environmental hygiene. Footbaths are generally viewed as helpful when disease is present at a low (less than 10 percent) level. When more animals are affected with disease, such as hairy heel wart, other methods must be employed for treatment.

Operating a dairy milking center involves managing a number of issues so a satisfactory end result is accomplished. It involves labor management, work routine organization, mastitis control, cow physiology, Grade A milk production regulations and agricultural economics. The involved parties may have different views of objectives and satisfactory results, so that has to be discussed and agreed upon. Once determined, the overall effort of running the milking operation must be aimed at meeting those objectives. The objectives need to be communicated to all involved from shift managers to milkers so everyone knows the procedures and goals.