Did you know that 50 percent of the milk that dairy cows produce is produced during the first 100 days of lactation? Though lactation typically lasts for 10 months or longer, a cow produces half of her milk – and is the most profitable – during the first trimester of lactation. Yet production records show that 25 percent of the cows that leave the milking herd do so in the first 60 days of lactation. So for one in four cows, just when they are the most productive and the most profitable, they disappear from the herd.
Fresh cows leave the herd for a number of reasons – most as a result of health and metabolic challenges that cause a dramatic reduction in milk production. The most common metabolic challenges are:
- Milk fever
- Retained placenta
- Displaced abomasum
The vast majority of the challenges that fresh cows endure are the result of poor management on the part of the dairy farmer during the late dry period and immediately after freshening. These metabolic challenges are directly related to environmental and nutritional management.
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Health of cows and dry period
The health of fresh cows and the potential milk they will produce during their lactation begins while the cow is still in the dry period. Often the problems that a fresh cow experiences, such as milk fever and ketosis, is the result of inadequate nutrition in the weeks leading up to the time she gives birth. During the dry period when the cow is not producing milk, her feed intake declines due to the reduced need for energy and protein. Rumen microbial population is reduced since there is less feed to ferment.
The transition from nonlactation to lactation is abrupt and the rumen must be ready for the increase in feed intake necessary to support milk production. The cow is genetically programmed to produce copious amounts of milk immediately after giving birth even while her digestive system may not yet be capable of digesting adequate feed to support the milk production. This leads to a condition known as ketosis, which is essentially a metabolic disease caused when a cow’s body begins to use up its fat reserves to get enough energy to support milk production.
Chemicals called ketones limit the synthesis of glucose and also makes the cow sick, causing her to not want to eat. This exacerbates the problem of negative energy intake and the ketosis only gets worse. Once a cow stops eating, her stomachs are left empty, allowing for the displaced or twisted abomasum. The cow’s nutritional intake spirals downward, milk production quickly drops off and the cow’s health is in jeopardy as she slowly starves. When ketosis or a displaced abomasum are not addressed quickly, cows will become too sick to recover and this is one reason they leave the herd in less than 60 days after they freshen.
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Nutrition can’t be ignored
Inadequate nutrition and vitamin/mineral intake during the dry period contribute to hypocalcemia, also known as milk fever. Calcium uptake at freshening to meet the demands of milk production must increase significantly. If a cow’s vitamin and mineral intake has not been properly balanced leading up to giving birth, her body’s ability to mobilize adequate calcium for milk production and muscle function will be compromised. While milk fever is easily treatable, studies estimate that an episode of milk fever will cost a dairy farm about $340 per incident. Low calcium will affect many muscular functions such as rumination and uterine involution. Cows that don’t clean properly after giving birth are estimated to cost an additional $285 per cow.
Poor cow health and milk production often center around improper management of the close-up dry cow and the transition from dry to milking. Poor quality forages and poor transition diets along with poor cow management contribute to poor nutrition, preventing adaptation of the rumen to diets that provide adequate metabolizable energy to the fresh cow. Inadequate dietary energy and a prolonged negative energy balance in early lactation will rob the cow and the dairy farm of valuable milk production that will not be recovered during the remainder of lactation.
Poorly designed dry cow facilities – pens and corrals – causing cow discomfort and overcrowding will also result in less than optimal milk production. Cows should have a minimum of 100 square feet of space in the maternity area when calving and feed bunks should supply a minimum of 24 to 30 inches of space per cow. Dry cow and maternity areas that are not well ventilated can become hot and oppressive during the summer, limiting feed intakes at the critical time of calving, which may cause the cow to be acidotic and develop laminitis later in the lactation.
Overcrowding in the close-up pen will have an even greater negative impact on first-calf heifers. Heifers are usually smaller in size than mature cows and may be pushed around by the bigger cows, preventing them from eating or resting as much as they should. Having facilities that allow heifers plenty of room, or keeping heifers completely separate from older cows, has reduced displaced abomasum and improved their first lactation milk production.
Cows a few days away from calving are known to drastically reduce feed intake and may stop eating altogether. It’s important that energy, protein and vitamin/mineral densities in close-up diets are formulated high enough so the cow’s digestive system doesn’t completely shut down when giving birth. Often, dairy farms feed the poorest quality forage to their dry cows and are remiss in providing a properly balanced ration to the dry cows.
The amount of milk a cow will produce during her lactation is greatly influenced by how she is treated during the dry period. Focusing on practical management and feeding practices that allow for maximum cow comfort, adequate resting and feed bunk space two to three weeks before calving will greatly improve a cow’s milk production during her lactation.
Read more: Dairy Nutrition: Subclinical Milk Fever