Summer heat and humidity are long gone. Despite the more ideal temperatures for cows, many farmers have been disappointed with production in the past few months.
    The fall milk slump is a real phenomenon. The United States Department of Agriculture statistics consistently show the lowest milk production per cow takes place in the last quarter of the year. In fact, November is the lowest month for milk per cow across most Midwest states. Conversely, milk components (butterfat and protein) are at a seasonal high. It is a good idea to always look at production on an energy corrected basis, particularly in the fall. Monitor combined pounds of fat and protein shipped rather than raw volume of milk.
    Numerous factors contribute to this fall reduction in milk. As with most production problems on farms, the problem cannot be solved with a single quick fix.
    Feed changes are often blamed for this fall depression in milk production. In some cases, these changes are significant and abrupt. However, several farms are in a position today to have complete or partial carryover of these wet corn sources for several months and still deal with lowest milk production in the fourth quarter.
    If new corn silage and harvested wet corn are a factor on your dairy, strategies to mitigate this production drop may be different. Incorporating rapidly digestible forms of carbohydrates may the best short-term solution. Recognize that starch availability in wet corn changes significantly as fermentation progresses and needs to be monitored in the months ahead.
    Heat stress has a prolonged effect on milk production. Summertime mid-lactation cows typically do not recover from summer heat stress, so they have depressed milk production during the fall. Early-lactation cows have reduced peak milk production during the fall season due to the negative impact of heat stress in the dry period. These cows also experience the stress of calving during heat stress, so it is common to see peak milk 5 to 10 pounds lower this time of year compared to previous months.
    Photoperiod and day length have a clear impact on milk production. In 2002, while at the University of Illinois, Dr. Geoff Dahl summarized 10 research trials showing an average increase of 4 to 5 pounds with long-day lighting. Milk production is highest when cows are exposed to 16 to 18 hours of bright light each day. Conversely, dry cows exposed to short days of about eight hours of light milk better after freshening than those exposed to long day lengths of summer.
    Energy requirements go up in the fall as animals prepare for cold weather. Dry matter intakes are often high this time of year, resulting in reduced feed efficiency. Cows commonly appear nonresponsive to dietary changes in the fall. In our midwestern climate, net energy for maintenance requirements dramatically rise for cattle in September and are greatest in late October and early November, not in the middle of winter like one might expect. Ruminants require as many or more maintenance calories to adapt to cold as compared to surviving cold. This preparation includes changing hair coats, placing fat under the skin for tissue insulation and raising basal metabolism. Most lactating dairy cattle are not housed in the outside environments in the winter, reducing the extend of these changes. However, they instinctively know it is going to get cold and will spend calories to prepare.
    The challenges with fall milk production are complex. The extent to which these factors impact production is unique to each farm and management system. Evaluate which solutions are practical for your dairy in the future. These may include controlled lighting, heat stress abatement, and efforts to manage reproduction and herd inventory variations. Work with your nutritionist and management team to evaluate and monitor feed changes. Let the cows tell you if you are making the right decision. They are always right.
    Barry Visser is a nutritionist for Vita Plus.