Nutrition Plus
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Dairy Nutrition Plus

Volume 12, Issue 3 May 2016


Negative DCAD is Best Way to Minimize Hypocalcemia

Negative DCAD is Best Way to Minimize Hypocalcemia

Hypocalcemia affects way too many transition cows. While clinical hypocalcemia only affects 3% to 5% of postpartum dairy cows; the big culprit is subclinical hypocalcemia.

Subclinical hypocalcemia can affect 25% to 40% of primiparous cows and 45% to 80% of multiparous cows, explains Jose Santos, professor of animal science at the University of Florida. Cows with subclinical hypocalcemia often have reduced dry matter intake, suppressed immune function, compromised energy metabolism, increased incidence of other periparturient diseases and reduced milk yield.

“Subclinical hypocalcemia is a hidden ghost that you do not see until you perform biochemical assays,” explains Santos. “You just do not know how prevalent this issue is on farm until you look for it.”

But it doesn’t have to be that way. Hypocalcemia – both clinical and subclinical – is highly preventable. Santos and his team reviewed the existing research to examine the methods available to control and reduce the impact of hypocalcemia in dairy cows. They concluded that dietary manipulation remains the best choice to control and prevent both forms of hypocalcemia. Limiting the intake of sodium, potassium and phosphorus in the diet and then manipulating the remainder of the macro minerals to achieve a negative dietary cation-anion difference (DCAD) for prepartum cows is the best way to beat hypocalcemia, says Santos.

Dietary options

Three dietary strategies were evaluated on their ability to reduce the risk of clinical and subclinical hypocalcemia. Limiting dietary calcium is one strategy. Research has shown that when cows are fed diets to induce a negative calcium balance, they have increased concentrations of parathyroid hormone which helps stimulate bone resorption, intestinal absorption and renal reabsorption. However, the challenge is in our ability to induce a negative calcium balance. To do so a diet must contain no more than 0.25% calcium to assure that intestinal absorption is less than the 20 grams of calcium that the cow needs. Since most forage, grains and byproducts fed to dairy cows have at least 0.25% calcium it is not easy to achieve.

Another option is feeding Zeolite to sequester calcium in the gut and create a negative calcium balance. Zeolites are complex structural compounds with interlocking molecules of SiO4 and AiO4 in the form of a honey-comb. The aluminum silicate formed carries negative charges that attract positively charged ions such as Ca2+ and Mg2+ in the gut. However, while research shows feeding Zeolite during the last 2 weeks of gestation was effective at improving calcium metabolism at the onset of lactation; it also decreased dry matter intake, and reduced blood concentrations of magnesium and phosphorus.

The third and preferred option is feeding a negative DCAD diet prepartum. Salts containing strong anions such as Cl- and S2- are fed to induce a mild metabolic acidosis in the last weeks of gestation. Research conducted by Weich et al., 2013, shows that feeding a negative DCAD diet in the final 21 days of gestation improved calcium homeostasis and increased milk yield by 12.3 lbs/day during the first eight weeks of lactation included in the study. Based on the available research, feeding a negative DCAD diet prepartum remains the best way to minimize clinical and subclinical hypocalcemia.

Putting DCAD to work

To successfully feed negative DCAD diets to prepartum cows, you need to do more than just add a handful of salts.

First, you must limit the intake of the strong cations sodium and potassium. Always select feed ingredients with low potassium, sodium, and phosphorus (and high chloride if available). Doing so will help you formulate a diet with a relatively low DCAD, between — 100 to 150 mEq/kg is achievable.

“It makes little sense to feed diets that are high in potassium and sodium and then try to counteract their effects by feeding large quantities of strong anions,” explains Santos. By first minimizing the strong cations in the diet you minimize the amount of strong anions needed to achieve a negative DCAD. When feeding acidogenic salts, less is better.

Other keys include:

  • Have current and continuous analysis of the mineral composition of feed ingredients fed prepartum. “Less than half of samples submitted to commercial labs request a mineral analysis,” he says. Use of book values for forages and byproducts will likely defeat your efforts to properly formulate a desirable DCAD target.
  • Limit concentrations of phosphorus in the prepartum diet. Research has shown that a prepartum dietary intake of phosphorus above 50 g/day increases the risk of clinical hypocalcemia (Lean et al., 2006). Prepartum diets should not contain supplemental phosphorus.
  • Magnesium enhances the cows’ ability to mobilize calcium from the bone at the onset of lactation and prevents hypomagnesemia. Most recommendations are for diets containing 0.4% to 0.45% Mg to result in intakes of 40 to 50 g/day.
  • With proper feed selection, most diets generally require fewer than 2.5 equivalents (Eq) of strong anions fed to achieve a desirable negative DCAD. Feeding a small amount of acidogenic salts minimizes the risk of suppressed DMI and increases the efficacy of the program.
  • The ideal DCAD to prevent hypocalcemia has not been identified. Current research suggests a DCAD range of -50 to -150 mEq/kg.
  • Urine pH is a good indicator of the degree of metabolic acidosis. In Holstein cows receiving a negative DCAD diet prepartum, strive for a mean urine pH between 6.0 and 6.5; in Jerseys a mean urine pH between 5.8 and 6.3. The key is to have a majority of cows tested, 70% to 80%, fall within the desirable range, 5.8 to 6.5.

Make a change

Hypocalcemia is a costly disease. The estimated cost of clinical hypocalcemia is about $300 per case. But the incidence in most herds is low. With subclinical hypocalcemia the estimated cost per case is about $125, but the incidence is much higher.

Take for example, a 1,000 cow dairy with a 3% incidence of clinical hypocalcemia. The annual cost would be $9,000 (30 cows x $300 per case). If that same 1,000-cow dairy has a 25% incidence of subclinical hypocalcemia the annual cost would be $31,250 (250 cows x $125/case). Subclinical hypocalcemia quietly steals your profits.

When implemented correctly, producers see a lot of success with negative DCAD diets. Once they see the reduction in clinical and subclinical hypocalcemia, have healthier cows with better starts, producers embrace the concept. Use negative DCAD to improve the health and profitability of your transition cows.

From the Maternity Pen
Consider Feeding Rumen Protected Choline

Want healthier more productive fresh cows? Feeding rumen-protected choline may help you accomplish that goal.

Research shows that feeding rumen-protected choline — both before and after calving — can improve milk production and the liver status of dairy cows in early lactation, explains Charlie Staples, dairy scientist at the University of Florida. Results have shown reduced incidence of clinical ketosis, fewer mastitis cases, less morbidity and increased milk production.

Choline is classified as a quasivitamin and is best known for its role in lipid metabolism. When cows are pregnant or lactating, concentrations of choline in the liver decrease dramatically. The accumulation of fat in the liver may result from a choline deficiency, which in turn may limit synthesis of phosphatidycholine and thus biosynthesis of very low density lipoproteins.

Much of the choline contained in feeds is metabolized by the microbes in the rumen. To get the benefits of added choline in the diet it must reach the small intestine. That’s where rumen-protected choline (RPC) comes in.

Staples reviewed the available research and summarized the results in a paper presented at the Southwest Nutrition Conference in February.

  • In a controlled study on a California dairy, cows fed 15 grams/day of RPC from 25 days prepartum through 80 days postpartum showed the following:
    • Milk production increased by 3.97 pounds of milk/day.
    • Morbidity decreased.
    • Clinical cases of ketosis dropped from 13.9% to 4.7% for primiparous cows and from 9.8% to 3.5% for multiparous cows.
    • Mastitis cases declined from 20% to 17.2% in primiparous cows and from 24.1% to 13.4% in multiparous cows.
  • In another farm study where primiparous cows were fed 15 grams/day of RPC the result was increased morbidity but milk tended to be greater by 1.8 lbs/day. However, the cows were only fed RPC for 22 days prepartum. The authors concluded that for health benefits to be realized in transition cows, RPC supplementation should continue into the postpartum period.
  • Cows had a positive milk production response to RPC in all stages of lactation studied. This suggests that choline may be a limiting nutrient for milk yield.
  • The positive response in milk yield and liver health does not appear to be affected by body condition score, crude protein content in the diet, or type of diet fed — high forage vs. high concentrate.

To read the full paper, “Potential Strategies for Successfully Feeding Choline to Dairy Cows,” go to:
http://dairynutritionplus.com/pdf-docs/potential-strategies-for-successfully-feeding-choline-to-dairy-cows.pdf

Consultants Corner
Get the Most Out of Long-Day Lighting

Geoffrey Dahl
  • Geoffrey Dahl
  • University of Florida

Photoperiod manipulation benefits dairy cows throughout the lifecycle. Not only does it increase milk production in the lactating herd; it also improves heifer growth, reproduction and dry cow performance. As a management tool it can help producers improve production efficiency and profitability.

A review of the research completed so far, and presented at the Penn State Dairy Nutrition Conference, shows the following:

Heifers

Long-day lighting (16 hours light, 8 hours dark) can help get heifers into the milking herd sooner. Long-day lighting from weaning to puberty increases lean body growth, increases parenchymal mammary tissue development — both before and after puberty — and it lowers the age of puberty by an average of one month. The effects of long-day lighting also persist into the heifers’ first lactation resulting in more milk. The chart below details research findings from Rius & Dahl, JDS, 89:2080-2083.

  Short-day lighting Long-day lighting
Body weight before calving (lbs) 1,404 ± 37.5 1,526 ± 37.5
Body weight after calving (lbs) 1,329 ± 48.5 1,413 ± 48.5
Withers height before calving (in) 55.4 ± 0.3 56.4 ± 0.3
Hip height before calving (in) 56.6 ± 0.4 57.7 ± 0.4
Age at first calving (months) 24.3 ± 1.1 23.1 ± 1.1
Peak milk (lbs) 73.2 ± 3.1 74.3 ± 3.1
Projected 305 FCM (lbs) 20,893 ± 571 22,546 ± 659

Lactating Cows

In lactating cows, long-day lighting increases milk yield. Research studies have shown that, on average, long-day lighting increases milk production by about 5 pounds per cow per day. Long-day lighting also increases production of the hormones IGF-1 and prolactin.

When used in combination with 3X milking, or with bST, the results can be additive. In addition, the dry matter intake of cows that receive bST and long-day lighting increases sooner than the DMI of cows on bST without photoperiod manipulation. That means the energy balance of cows on long-day lighting and bST does not decrease despite the increased milk yield.

Dry Cows

When cows are dry, they need the opposite. Short-day lighting (8 hours light, 16 hours dark) increases DMI during the dry period and increases milk production in the next lactation. In addition, mammary growth increases with short-day lighting in the dry period. These effects are due to lower prolactin, as prolactin replacement reverses the effect of short days.

Remember, when doing short-day lighting dry cows must also be cooled. If the barn has solid sides mechanical ventilation will be needed.

Putting it all together

Research has given us a framework for using photoperiod management throughout the life cycle of dairy cows. The chart below illustrates the concept. To learn more, please see “Photoperiod Management of Dairy Cattle: Considerations and Applications.”
http://extension.psu.edu/animals/dairy/courses/dairy-cattle-nutrition-workshop/previous-workshops/2015/breakout-and-special-sessions/photoperiod-update

Photoperiod management throughout the life cycle of dairy cows.

Beyond Bypass
Forage Testing Pays

Forage Testing Pays

We routinely feed 60 to 65 percent forage in the ration with great results. The key to that success, explains Daniel Laparde, BKC Dairy Nutrition, Rocky Mount, VA, is routine forage testing.

Regular testing of forages provides a baseline; a history of forage quality. It also makes it easier to spot and quantify a change in forage quality and correct the ration to avoid a nutritional insult for the cows. Even a small change in energy density of the forage can translate into a big change for the cow. Your goal should always be to feed a consistent quality meal every time. Failure to meet that goal can lead to less milk production, lower peak milks and more health issues.

“I can’t control everything. But I want to take control of what I can in order to deliver a consistent feed to the cows,” Laparde says. Routine forage testing allows me to minimize change and deliver a consistent quality TMR to the cows.

Laparde prefers to test forages once a month, plus whenever a new pile or bunker gets opened, or if he has reason to suspect a change in quality.

He also tests dry matter of the forages fed each week with a Koster tester. He strives to feed a TMR with consistent moisture content. If the TMR dry matter is normally 50 percent, a sudden decline can lead to more separation of small particles. And that changes what the cows actually eat. Sometimes he adds water to the TMR to maintain the goal of 50 percent dry matter.

Always be on the lookout for changes in forages. If there is a corner of a bunker that doesn’t look good; looks moldy or different, discard it. “It is a nutritional insult waiting to happen,” he says. “It’s not worth feeding it to a lower production group or growing heifers. It should be fertilizer on the field.”

Consistency is important for all animals; but close-up, pre-fresh and high groups are the most likely to develop problems from sudden changes in forage quality.

For Laparde, 25 plus years as a dairy nutritionist has demonstrated the value of forage testing. The more things we do to keep cows healthy the better. You don’t want to be buying band-aids for nutritional insults. Prevent those insults instead.

Invest in routine forage testing. The cows will thank you.

Happenings
SoyPlus® Expansion On Track for Fall 2016 Production

A major expansion for SoyPlus® production remains on track for new tons to be manufactured beginning Fall 2016.

Last June, company officials announced a $27 million expansion slated to result in 50 percent more SoyPlus production. Site work began almost immediately last summer. Today, the new process building is enclosed, new storage silos are in place and major production equipment is moving in.

In late March, plant manager Randy Daniel oversaw installation of a state-of-the-art dryer. “SoyPlus is known for its consistency and quality and the dryer we use in our process is one of two pieces of equipment that create that consistency and quality,” Daniel said.

Daniel noted the second critical piece of SoyPlus production equipment, the presser, is expected to arrive early this summer. “Pressing the oil out of the soybeans grown by our cooperative’s farmers is the foundation for our SoyPlus process,” said Daniel.

“When we start-up the new production line, our goal is that customers will not be able to tell the difference between what came off our existing line and what came off the new line,” Daniel said.

The SoyPlus facility has already hired eight new employees with four more needed as the plant expansion nears completion. You can follow the progress of the plant online at facebook.com/DairyNutritionPlus.

SoyPlus expansion progress.
SoyPlus expansion progress.

Quality Corner
Successful Lactations Start with SoyChlor

Successful Lactations Start with SoyChlor

The nutritional concept of lowering dietary cation-anion difference (DCAD) for pre-calving cows to improve calcium status at calving has been well researched in the last two decades. Reducing the incidence of clinical milk fever has been enough to justify DCAD management practices for a growing number of operations. Even beyond these benefits, anionic supplementation has been shown to reduce the incidence of many other transition and early lactation disorders.

In recent years, research efforts have shown multiple benefits of higher blood calcium concentrations at calving. In the September 2013 Journal of Dairy Science, a research team at the University of Florida reported on the prevalence of early lactation diseases and their effects on fertility of cows in grazing situations. While grazing herds represent a small portion of U.S. herds, the information focuses attention on transition management of cows in all feeding situations.

The researchers found high incidences of several metabolic disorders, some of which were related to lower levels of blood calcium in early lactation. Low blood calcium was associated with elevated indicators of ketosis, as well as to the prevalence of uterine disease. Both clinical and subclinical diseases had negative effects on reproduction, and were associated with extended time to first estrus and increased number of services per pregnancy.

By now, there should be ample evidence supporting the benefits of anionic dietary supplements for adjusting DCAD in prepartum cows. When choosing an anionic supplement, keep in mind the long, successful track record of SoyChlor® and its high concentration of chloride ions and beneficial contributions of highly bioavailable calcium and magnesium.