Nutrition Plus
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Dairy Nutrition Plus

Volume 13, Issue 6 November 2017


Use Nutrition to Help Combate Heat Stress

Understanding New Research on Subclinical Hypocalcemia

For dairy cows, a blood calcium level of 2.0 mM (8.0 mg/dL) or higher has been the diagnostic standard for normal for many years. Blood calcium levels less than that were characterized as too low or hypocalcemic. However, recent research reports have used several different and higher thresholds for blood calcium levels to differentiate between normal and subclinically hypocalcemic status. Higher blood calcium thresholds increase the apparent prevalence and incidence of subclinical hypocalcemia reported. At first glance it may appear that the diets with negative DCAD (dietary cation-anion difference) fed prepartum in the studies are not working as well as they have in past research. But that’s not the case.

The change in blood calcium thresholds used in research is about examining negative outcomes, explains Thomas R. Overton, professor of dairy management at Cornell University. Negative outcomes include less milk production, reduced reproduction efficiency and the common metabolic diseases that often plague just-fresh cows. Researchers are trying to determine if certain blood calcium levels can predict specific negative outcomes.

“The cut-off for subclinical hypocalcemia remains unclear and the exact value that this threshold should be remains greatly unanswered at this point,” says José Santos, professor of animal sciences at the University of Florida. “We still do not know if the issue is a single day with blood calcium levels below a particular threshold or a combination of threshold and duration that determines the subsequent negative outcomes on the cow.”

Traditionally, blood calcium has been tested on day 1 or day 2 after calving to diagnose hypocalcemia. But prevalence rates for subclinical hypocalcemia drop quickly from day 1.

“We just don’t know the best time to test blood calcium relative to calving—day 1, day 2, or day 3,” says Overton. “Some cows bounce right back despite low blood calcium and others remain sluggish for several days.” It may be more important to know which cows’ blood calcium levels stay low, as opposed to how many were subclinical on day 1. It appears that when trying to predict negative outcomes, it may be better to test blood calcium levels two or three days after calving.

Several recent studies that have used higher blood calcium thresholds indicate that different blood calcium levels may indeed be able to predict negative outcomes. Research by Rodriguez et al., 2017 looked at the associations between subclinical hypocalcemia and several common fresh-cow diseases. While more research is needed, they did identify several different blood calcium thresholds that indicated different problems ≤1.93 mM for ketosis, ≤2.05 mM for retained placenta and metritis and ≤2.10 mM for displaced abomasum.

The information on blood calcium thresholds available right now is incomplete, it’s not definitive, explains Santos. More research is needed to evaluate the consequence of a particular threshold on health, survival, production and reproduction. But one thing is certain, feeding a diet with negative DCAD prepartum increases milk production, increases dry matter intakes, increases blood calcium levels and helps cows transition better.

Negative DCAD Works

Feeding a diet with negative DCAD helps cows prepare for the transition to lactation. It “primes the pump” for calcium mobilization by the cow once she freshens, says Overton. This speeds her recovery and helps her have a successful transition with fewer negative outcomes.

“Diets with a negative DCAD have clearly been shown to reduce the risk of milk fever and to reduce the incidence and prevalence of subclinical hypocalcemia,” says Santos. This has been widely reported in the literature.

To determine if a diet with negative DCAD reduces subclinical hypocalcemia or not, you must compare diets with a negative DCAD to diets with a positive DCAD. These new studies are not testing whether or not negative DCAD works. They are using diets with negative DCAD as part of the study design because it is a proven concept. The next step is now looking at different blood calcium thresholds as predictors of negative outcomes, or to evaluate a protocol that may help further reduce the incidence of subclinical hypocalcemia and the problems that often go along with it.

Take, for example, a study recently completed by Vieira-Neto et al., 2017. Researchers were testing if a single injection of calcitriol (the active form of vitamin D3) after calving could reduce the prevalence of subclinical hypocalcemia and influence immune function. The blood calcium threshold used in the study was 2.125 mM. (It was selected because Martinez et al., 2012 showed that 2.125 mM was the best predictor of uterine diseases in dairy cows.) In the study the daily prevalence rate of subclinical hypocalcemia during the first three days in milk averaged 56.6% for control cows fed a diet with negative DCAD compared to 6.8% for cows that received an injection of calcitriol after calving in addition to a diet with negative DCAD. If the current diagnostic standard for blood calcium of 2.0 mM had been used to determine the daily prevalence rate of subclinical hypocalcemia during the first three days in milk, it would have been 33.3% compared to 6.7%. This experiment was proof of concept for calcitriol used in addition to a diet with negative DCAD fed prepartum. More research is needed to determine exact dose and benefits of the protocol.

Don’t get distracted by the higher rates of subclinical hypocalcemia reported in new research when higher blood calcium thresholds are used. The threshold value used in any experiment provides a reference point and guide so fair comparisons can be made across treatments within that experiment, says Santos. The key for nutritionists and producers to remember is that implementing dietary and management strategies, such as feeding negative DCAD, that have been proven to reduce hypocalcemia in dairy cows, works.

DCAD on Your Dairy

The amount of acidification, or negative DCAD, needed will vary by farm says Overton and Santos. There is no one size fits all. Diets with negative DCAD must be tailored to each dairy based on the feeds available, the mineral content of those feeds, mineral content of water and the management available.

Monitoring urine pH on farm is the best way to know if your diet with negative DCAD is working. Your goal is to have the majority of cows within the expected pH range of 5.5 to 7.0. Cows with a higher level of acidification will have a lower pH and vice versa. Remember, the level of negative DCAD needed to acidify cows will vary by farm. And some dairies that choose to feed a less negative DCAD can get similar results.

For best results, feed a consistent diet, test the mineral content and tailor the level of negative DCAD to get the results you want, and aim for a DMI of 22 to 24 lbs/day for nulliparous cows and 25 to 28 lbs/day for multiparous cows. Test urine pH and track health records on your farm. Monitor these results and look for deviations from normal for your dairy. Use that information to decide when to tweak diets.

From the Maternity Pen Body Weight Loss Is Intrinsic Trait

Dairy Nutrition Plus | Photo of Cows feeding in a Barn

New research from the Agriculture Research Organization, Volcani Center, in Israel is the first to demonstrate a consistent magnitude of body weight loss after calving across multiple lactations. This suggests the degree of body weight lost after calving is an intrinsic trait.

Researchers conducted a retrospective study using the records of 92 randomly-selected cows with at least four full lactations. Cows were divided into two groups based on the magnitude of body weight loss during the first five weeks of lactation. High weight loss (HWL) cows lost 7% to 17% of body weight. Low weight loss (LWL) cows lost -3% to 6% of body weight. The average percent of body weight loss between week one and week five of lactation was 7.6% for HWL cows and 5.3% for LWL cows. However, the percentage of body weight loss increased with each additional lactation for HWL cows, but moderately decreased for LWL cows.

The difference in body weight loss also affected reproductive performance. Across the four lactations studied, HWL cows spent 17 more days open and had a calving interval that was 20 days longer than LWL cows. In addition, the number of days open increased for each additional lactation for HWL cows, but not for LWL cows. LWL cows also had consistently higher conception rates across all four lactations.

Read the full study, “Consistent Magnitude of Postpartum Body Weight Loss Within Cows Across Lactations and the Relation to Reproductive Performance,” in the April 2017 issue of Journal of Dairy Science.

Happenings The Cooperative That Ties It All Together

Do you know where your feed comes from? The Dairy Nutrition Plus product line, manufactured by Landus Cooperative, offers a unique advantage in your supply chain story. With SoyPlus, you know where your high quality, consistent high bypass protein soybean meal comes from, because the manufacturer can tell you how soybeans are grown and what they become. The SoyPlus team is proud to tell the whole story of this 100 percent natural bypass protein source.

Soybean Harvest at Sunset

From breeding better soybean seed for local soils to providing agronomic advice throughout the growing season to processing those beans at an ISO and HACCP certified manufacturing facility, the farmer-owned cooperative manufacturing SoyPlus is involved every step of the way.

Learn more about the farmers growing the soybeans that become SoyPlus and the cooperative that oversees the entire process by watching the full story.

Consultants Corner Inflammation and Immunity in Transition Cows

Barry Bradford, Kansas State University
  • Barry Bradford
  • Kansas State University

In order to make a successful transition to lactation, dairy cows must first run the gauntlet. With a myriad of diseases waiting to attack, cows must receive top notch management in order to overcome the challenges presented during transition.

Immunity and inflammation are two of the biggest challenges. The fact that a cow’s immune system doesn’t function optimally during transition has been well established. But recent research has revealed that inflammation, especially inflammation that lasts more than one or two days after calving, affects cows too. At this point it is not clear if inflammation compounds the immune system dysfunction or if it is a separate problem that occurs at the same time in transition cows.

Many studies have shown that cows with infections or metabolic disease have more inflammation which lasts longer. In addition, research has shown that cows with a greater degree of inflammation are at greater risk of subsequent health problems.

Based on what is known today, my theory is that some inflammation is normal at calving. However, those animals with the most problematic immune dysfunction don’t respond adequately to normal pathogenic challenges that cows experience during transition. They also might not properly trigger the resolution phase of inflammation after calving. As a result, the impact and duration of inflammation varies greatly in cows.

A study by Sabreda et al., 2012, using blood biomarkers of inflammation found that at peak inflammation, about one or two days after calving, some cows have five to 10 times greater concentrations of these biomarkers than other cows. Perhaps more importantly, the biomarkers in healthy cows returned to normal (baseline) concentration by about day five of lactation. Other cows had elevated inflammation biomarkers for more than three weeks.

Research has shown that early lactation inflammation can impair milk production throughout lactation, fertility and overall cow health. Current research using anti-inflammatory products and immune stimulating products looks promising. But many questions remain about the tradeoffs between inflammatory status and immunity. This makes it difficult to give a one-size-fits-all recommendation. Based on the evidence available today, I suggest that farms with more infectious disease problems during transition focus on immune function; and those with more metabolic disorders during transition focus on anti-inflammatory strategies.

Review your annual records for transition cow diseases to see if your farm has more metabolic or infectious disease issues. (For some farms the first step may be keeping better transition cow records.) No matter what transition cow issues you see on farm, all producers should:

  • Feed a diet with negative DCAD prepartum (dietary cation-anion difference).
  • Eliminate over conditioned cows. Strive for a body condition score ≤ 3.5.
  • Don’t overcrowd prepartum or just fresh cows. Environments that prevent sufficient access to feed increase cows’ risk of immune and metabolic disorders.

In addition to the above items, dairies that have more infectious disease problems should feed sufficient prepartum dietary antioxidants (vitamin E and selenium) and a DCAD diet. A strong DCAD program can help support fresh cow immunity, even if clinical milk fever is rare. Once those steps are taken, a couple of new tools include dietary immune-modulators and a pharmaceutical product that increases the number of immune cells.

For dairies with more metabolic issues, some evidence suggests adequate prepartum fat-soluble vitamins and postpartum omega-3 fatty acid supplements can help counteract inflammation. In addition research with some polyphenols (compounds found in nearly all plants) has shown potent anti-inflammatory effects which decreased plasma NEFA levels and increased milk production (Winker et al., 2015).

Before you try a new product, make sure the feeding program, management and monitoring system is in place for success. Then, it is a bit of logical trial-and-error to see what works on your dairy.

Beyond Bypass Make Shoulder Silage as Good as the Center

Photo of a tractor in a field

Silage stored in a bunker is prone to deterioration, especially at the shoulders of the bunker. Even with proper harvest, packing and covering the top, deterioration can still occur. Researchers at the Federal University of Lavras in Brazil wanted to find a way to minimize losses at the shoulder.

They compared two systems. The first used a thin oxygen barrier film positioned along the length of the sidewalls with 6.5 feet of film overhang. Once the bunker was filled the overhang was folded across the top of the bunker and covered with a top sheet of polyethylene. The second system used a single thick polyethylene film cover over the top of the bunker. Gravel-filled bags were placed along the sidewalls and in the center of the bunker to weigh down the plastic barriers.

The two-step oxygen barrier system reduced dry matter and nutrient losses at the shoulders of the bunker compared to shoulder silage with just a top cover. The shoulder silage stored with the oxygen barrier also had a better fermentation profile and lower spoilage microorganism populations than the shoulder silage with only a top cover.

Researchers also compared shoulder silage to silage in the center of the bunker. Almost all fermentation, microbiological and nutritional parameters for shoulder silage stored with oxygen barrier sidewalls were the same as silage stored at the center core of the bunker. The exceptions were that shoulder silage stored with the oxygen barrier sidewalls had less lactic acid concentrations and greater yeast counts than silage stored at the center core of the bunker. Researchers concluded that this two-step system could produce shoulder silage with similar characteristics to silage stored at the center of the bunker.

Read the full study, “Lining Bunker Walls with Oxygen Barrier Film Reduces Nutrient Losses in Corn Silages,” in the June 2017 issue of Journal of Dairy Science.

Quality Corner Fully Absorbed Chloride Makes a Big Difference

Dairy Nutrition Plus | SoyChlor®

Unlike traditional anionic salts that contain large chunks of salt, SoyChlor is made using a wet manufacturing process. This wet process allows chloride ions to be fully absorbed into individual feed particles, creating an end product that is smooth, cohesive and reliable.

Traditional Dry Process

Traditional dry process for anionic salts does not allow any chloride absorption into feed particles. The following issues result:

  • Unpalatable salt particles separate from the palatable feed particles, decreasing palatability.
  • Separation worsens during feed mixing and transportation.
  • Decreases ration consistency.

SoyChlor Wet Process

Chloride ions fully absorb into feed particles as a result of SoyChlor’s wet process. Benefits include:

  • Increases palatability by dispersing chloride at molecular level of feed particles.
  • Reduces separation during feed mixing and transportation.
  • Improves both ingredient and ration consistency.

The way your anionic supplement is manufactured matters. SoyChlor’s wet manufacturing process is just one factor contributing to the product’s consistency. Want to learn more about how SoyChlor is made? Click to learn more