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Nutrition 101 for prepartum cows

Jennifer Janak Published on 17 October 2014

Throughout a cow’s life cycle, the transition period is the most critical stage to maintain so that she may be productive during the subsequent lactation, but it is often the trickiest for commercial dairy producers to manage.

Turbulent transition periods will limit profitability of the cow for her entire lactation by decreasing milk yield and reproductive success while causing an unforgiving amount of health problems.

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To avoid such misfortunes, there are three key management areas on which to focus: health care, cow comfort and, arguably the most important, nutrition during dry and fresh periods.

Nutrition management lessens metabolic risks
Dr. Jim Drackley, professor at the University of Illinois, has discovered that nutritional management can optimize fertility and minimize the chances of developing metabolic imbalances in high-producing cows.

Due to the drastic change in metabolizable energy requirements two days before calving and two days afterward, proper nutrition helps minimize the effects of negative energy balance (NEB) and the occurrence of metabolic diseases.

On average, the typical transition cow will receive more energy per day than what is required prepartum, according to Drackley. After calving, a transition cow may only receive 65 percent of her required energy, most of that being put toward milk production, causing NEB.

The same is true for metabolizable protein.

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“It’s easy to blame the high-producing cow for NEB,” Drackley says. “But that isn’t the case.”

In fact, research has confirmed that NEB is not correlated with milk yield but rather dry matter intake (DMI). The less a cow is consuming prior to calving, the more likely she is to have a high NEB. Promoting high DMI immediately after calving will decrease the chances of metabolic issues related to NEB.

Metabolic problems that may arise
Increasing DMI is one of four tactics to improve the health of the cow during this stressful period, specifically focusing on nutrition. The others include managing dietary and body energy, maintaining adaptation and health of the rumen, and minimizing the risk and effects of hypocalcemia and hypomagnesemia.

“In managing dietary and body energy, it’s important for the cow to maintain a moderate body condition score,” Drackley says. “Also, being able to meet the energy requirements at prepartum but not allowing excessive energy intake.”

In Drackley’s opinion, he suggests a pre-calving body condition score of about 3 to have the most successful transition into lactation.

Failure to monitor these four tactics results in body fat mobilization from NEB. This reaction in the body increases the concentration of non-esterified fatty acids (NEFA) in the blood, more commonly referred to as free fatty acids.

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Most metabolic issues arise after NEFA have accumulated over a period of time. The most common time for this to occur is immediately after calving and the few days that follow.

Until DMI improves, the cow’s metabolic system undergoes a “doom loop,” as Drackley likes to put it. He defines this as a time when elevated NEFA in the blood increases fat accumulation in the liver, resulting in severe impacts.

The results of this doom loop can be devastating if not monitored properly, causing an increased risk of ketosis and displaced abomasums. Other issues include impaired reproduction, decreased milk production and a higher occurrence of culling and death loss.

Ten days postpartum, the cow typically begins to increase DMI and energy balance, resulting in decreased levels of NEFA and fat in the liver.

Similar to accumulation of fat in the liver, high levels of NEFA lead to increased ketones. Historically, ketones were measured in urine or milk, but they have more recently been measured as beta-hydroxybutyrate (BHBA) in blood.

A survey of TMR-fed herds in the Northeast with elevated levels of NEFA or BHBA postpartum were at 4.4 times greater risk for metritis, displaced abomasums or clinical ketosis. Similarly, these herds also displayed a 13 to 16 percent lower risk of pregnancy and nearly 1,500 pounds less energy-corrected milk.

“Based on the survey, NEFA and BHBA are associated with very real, very important metabolic outcomes,” Drackley says.

Eliminating the risk of such problems will improve the cow’s reproduction and production as she continues throughout her lactation.

Understanding your cows
“Many would argue that overconditioned cows are the problem and have always been the problem,” Drackley says. “They are more prone to low feed intake after calving and exhibit higher levels of ketones and fat in the liver.”

However, research has shown that cows that are physically fit may also show signs of metabolic problems postpartum, if not monitored. These issues may occur due to excess energy consumption, leading to a 75 percent increase in visceral adipose tissues (bad fat) that drain directly to the liver.

“Too much energy during the dry period might be a bad thing,” Drackley says. “Cows respond metabolically as if they were too fat, even if they don’t appear to be.”

It’s important to choose a diet that will benefit your cows. Drackley performed studies based on three different prepartum diets to determine the effects of each on a cow’s metabolic system and other factors that determine health of the cow. The diets included high-energy ad libitum, restricted high-energy and low-energy/high-bulk (straw) ad libitum.

It was concluded that no particular diet greatly affected milk yield, and the restricted and high-bulk diets were metabolically equivalent. However, depending on the management of a farm, certain diets should be used.

A high-energy diet fed ad libitum is twice as likely to lead to liver fat deposits after calving than the other two diets. While this particular diet is highly correlated with negative consequences, it is likely to be successful in well-managed herds.

“We found that excess energy intake during the close-up period increased days to pregnancy by 10 days,” Drackley says. “This was in comparison with a controlled-energy diet, either high-bulk ad libitum or restricted high-energy.”

Drackley also notes that dairy producers who choose to use either of the latter diets in a two-stage approach will likely not see a clear and consistent advantage if prepartum and postpartum forages are similar.

Taking all aspects into consideration, discuss with your nutritionist the best approach to making a successful transition period for your herd. PD

Drackley presented this information at the 2014 International Cow Fertility Conference held in Ireland on May 18-21, 2014.

Jennifer Janak is a 2014 Progressive Dairyman editorial intern.

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