Caring for the Lactating Dairy Herd in Extreme Cold

Caring for the lactating dairy herd in extreme cold conditions also has its challenges. If not properly cared for producers may see a decline in performance including total milk production, increasing somatic cell counts due to mastitis, losses in reproductive efficiency and even decreased growth in young first calf heifers if the extreme cold continues for extended periods of time.

Thermoneutral Zone

Even though a majority of lactating cows are housed inside throughout the year there are still some important factors to remember. The thermoneutral zone is the environmental conditions where a cow does not expend extra energy to either cool or heat its body. In dairy cattle this range is between 40º to 68º F for a lactating dairy cow. If the ambient air temperature is on either side of this range, the animal will adjust its energy usage via thermoregulation. It will either warm or cool itself instead of putting the energy from the diet towards growth, reproduction, production and maintenance. Factors that can affect the upper and lower critical temperature, when combined are the base air temperature, wind, and humidity. Adequately managing the dairy herd through these swings in the thermoneutral zone will improve overall performance of the lactating dairy herd.

Water Sources

In extreme cold conditions we must first remember to provide an adequate amount of water on a daily basis. Adequate water consumption is critical to maintaining feed intake, milk production levels, reproductive efficiency and overall metabolic function. A lactating dairy cow on average consumes in excess of 15 gallons of fresh water per day. Water sources should be checked throughout the day in extreme cold to make sure they are not frozen and working properly. It is important to not let ice buildup happen near waterers which can cause injury due to slips and falls.

Facilities

Take a look at your facilities, do you have ripped curtains, holes in your wall, or doors that do not close adequately? Is it causing unnecessary drafts which may cause frost bite? Check your barn fans, if they are not functioning properly they are not circulating the air causing increased humidity in the barn, resulting in increased pneumonia risk and frost buildup. If cows are housed outside provide wind protection and adequate clean, dry, deep bedding. Keep in mind cattle with a good long hair coat are able to trap warm air in and around the hairs, allowing the body to stay warmer. Whereas a wet haircoat or a haircoat covered in manure will provide less protection from the cold letting the body heat out and cold air in.

Teat Dips

Continuing to teat dip is still a necessity and essential to minimize mastitis risk. You still want to use a teat dip that has an effective germicide while also providing a skin conditioning agent. Some practices that may help are dabbing the teat end with a clean towel once the post dip has been applied if the cow will be exposed to wind chills directly post milking. Do not dry the entire teat which essentially removes the dip. The other option is to just dip the teat end in extreme cold temperatures. Try to allow enough time for the teats to dry before exposure to colder temperatures outside the milking parlor or barn. Warming the teat dip helps reduce drying time. Keep in mind fresh cows with swollen udders are more susceptible to chapping.

Diet Adjustments

Even though dairy cattle are ruminants and producing their own heat as they digest feedstuffs it will still be necessary to make diet adjustments based upon the temperature, wind protection, overall body condition, milk production levels, along with the body growth and maintenance needs of the animal. Work with your nutritionist to adjust diet dry matter intakes and energy levels during extreme cold weather periods.

Other Considerations

Other considerations to keep in mind in the dairy barn is making sure that all smoke & fire detectors are in working order. Using caution and common sense if a portable space heater is needed. Do not place near flammable items such as paper towels or bedding, making sure they cannot be tipped over easily. Lastly, make sure your vaccines that are temperature sensitive are properly stored. Frozen vaccine inactivates the vaccine and they are now no good, costing you money while providing no benefit to the animal. The same can also be true for certain antibiotics.

What Makes a Cow Fertile?

Why do cows fail to get pregnant when you do everything right? Having a healthy cycling cow in heat, bred by an experienced technician is not enough to ensure a viable pregnancy. There are two crucial things that must occur prior to breeding for any real chance of producing an embryo that will survive to term.

High Progesterone

The first essential item for a lasting pregnancy is high progesterone. Not the progesterone needed to sustain the pregnancy once it has been created, but progesterone prior to fertilization. Numerous studies eshow for the developing oocyte to be able to fertilize and make an embryo that will survive to term, it must grow under high progesterone during its last days prior to ovulation.

The second critical factor to producing a viable pregnancy is to ovulate a follicle that is not too old and degenerate or too young and immature. To make an embryo that is the strongest and survives the best, we must breed a fresh, competent oocyte (the unfertilized egg, which is released from the follicle), and this is often a problem for lactating dairy cows. There are a high percentage of natural heats that ovulate aged dominant follicles. These cows often appear as strong heats, have great mucous and uterine tone, but the oocyte is aged. Most of these aged oocytes will fertilize, but they make small weak embryos that do not survive well.

Both follicle competency and adequate progesterone during its development are essential for maximizing fertility. It is the reason some dairies are attaining conception rates exceeding 60% using first-service synchronization programs such as the G6G or the Double Ovsynch. Interestingly, when you look at the last three injections in these two popular programs, it’s still the original Ovsynch program that finishes them.

Enhance Survival

The only difference in these programs is the shots that precede the Ovsynch. Those are meant to synchronize cows at around days five to eight of their cycle. At this time most lactating cows have a next follicular wave large enough to ovulate, and the first GnRH injection of the Ovsynch is meant to get rid of older, less fertile follicles/oocytes.

Starting cows around days five to eight of their cycle results in higher ovulation rates. By removing the dominant follicle and its hormones, we start a new follicular wave that will ovulate a fresh oocyte, making an embryo that has the best chance of surviving. Another benefit of starting cows in Ovsynch at that time is most cows will have an active corpus luteum (CL) producing enough progesterone to grow a fertile follicle/oocyte.

These first service programs attain amazing conception rates, but what about the cows that do not conceive? How do we resynchronize them if we fail to observe a standing heat or our conception rates are too low with natural heats?

In subsequent articles I will discuss the challenge in managing these cows reproductively and some strategies to apply to achieve higher conception rates.