Arm & Hammer Animal Nutrition

Research Roundup: What’s New in Dairy Nutrition?

Proper nutrition plays an obvious and significant role in helping calves get off to a good start. And in supporting cow health and productivity—especially throughout the transition period.

A number of recent dairy nutrition research developments are helping to shed additional light on ways dairies can positively influence animal health and performance with every bite of feed.

 

More Health Benefits to Negative DCAD Balancing in New Meta-Analyses

A preview of two upcoming, complementary meta-analyses offer more evidence regarding the health benefits of reducing DCAD levels of prefresh diets.

In the first analysis1, U.S. and Australian researchers explored the effects of prepartum diets differing in DCAD intake on metabolism and postpartum production and health, and the potential for differences in intake of other dietary macro minerals to influence responses to differences in DCAD. The meta-analysis evaluated 58 comparisons from 31 experiments featuring 1,571 cows.

Data show diets with lower DCAD:

  • Increased milk yield in multi-lactation cows
  • Increased fat-corrected milk yield, especially in multi-lactation cows
  • Milk fat percentage, milk fat yield and milk protein percentages were not affected by treatment, although milk protein yield tended to increase in cows fed the lower DCAD ration
  • Increased blood calcium and phosphorus on the day of calving and calcium postpartum

The lower-DCAD rations also decreased blood beta-hydroxybutyrate (BHB) in treated cows before calving. Reducing DCAD in rations of prepartum cows resulted in decreased risks of milk fever and retained placenta. It also reduced the odds of metritis and overall disease. 

The second meta-analysis2, also conducted by U.S. and Australian researchers, included 42 experiments involving 134 treatments and 1,803 cows. Data collected included the mineral composition of prepartum diets, parity group prepartum, breed, days on treatment, and means and respective measure of variance for urine pH, dry matter intake (DMI), body weight, body condition, productive performance, concentrations of minerals and metabolites in blood, and disease incidence.

Interestingly, this analysis notes that reducing the DCAD of diets fed to prepartum cows reduced DMI prepartum but increased postpartum intake.

Data indicate:

  • Multi-lactation cows produced more milk, fat-corrected milk, fat and protein when fed rations with lower DCAD levels prepartum.
    • The effect was not the same for first-lactation cows.
  • Reducing the DCAD reduced the incidence of milk fever in first-lactation cows and the incidence of retained placenta and metritis in all cows.
  • Little-to-no impact was observed from manipulating the dietary contents of calcium, phosphorus or magnesium in prepartum diets.
    • However, increasing dietary calcium tended to increase the risk of milk fever in first-lactation cows, particularly in those fed diets with positive DCAD.

Once again, these findings support the recommendation of feeding rations with lower DCAD levels to cows. This practice improves calcium metabolism around calving, reduces the risk of milk fever and uterine diseases, and improves lactation performance.

 

Why does DMI drop prepartum?

A recent research trial3 examined the underlying reason for dry matter intake depression that can occur with feeding prepartum rations formulated for negative DCAD. These results, too, will be published soon.

In the trial, pregnant Holstein cows were assigned to dietary treatments designed to manipulate the contents of sodium, potassium and chloride, and to result in basic or acidic diets.

Feeding acidifying diets induced a compensated metabolic acidosis and reduced dry matter intake; however, incorporation of alkalogenic salts to buffer the acidogenic diet prevented the decline in DMI. The reduction in DMI observed in diets with low DCAD is mediated by acid-base status and not by inclusion of chloride salts.

One important thing to note is that supplementation of sodium sesquicarbonate and potassium carbonate to the diet containing the diet-acidifying product prevented dry matter intake depression. Lower intakes were observed when only the acidifying product was added to the diet.

These results support the concept that inducing metabolic acidosis seems to be the underlying reason for the reduced DMI seen when cows are fed diets containing acidifying products and not the products themselves.

 

Heifer Health

A recent trial4 conducted at two Wisconsin dairy farms evaluated health and performance of milk-fed commercial Holstein calves supplemented with Refined Functional Carbohydrates™ (RFC™). RFCs help provide a healthy foundation for dairy calf and heifer development by helping support the beneficial bacteria of the intestine while blocking sites for attachment by certain pathogens.

RFCs are the components harvested from yeast cells (S. cerevisiae) using specific enzymes during the manufacturing process to ensure a high level of bioavailability. This proprietary enzymatic hydrolysis yields:

  • Mannan oligosaccharides (MOS)
  • Beta glucans (1,3-1,6)
  • D-Mannose

 

Research and Results

During this on-farm study, calves were housed individually indoors for days 1 – 6, then group housed with an automatic feeder until day 56. Three-day-old calves were randomized into treatments with about 80 calves per treatment.

Throughout the trial calves were monitored for overall health, fecal pathogen shedding and average daily gain (ADG) during the preweaning period.

Researchers noted treatment interactions during the trial, along with interactions between farm origin, study week, study month and calf passive transfer status.

However, the following overall conclusions provide valuable lessons from the trial:

  1. RFCs numerically reduced predicted probability of severe diarrhea (P=0.15) as shown in Figure 1. 

     

  2. RFCs also reduced the prevalence of Salmonella (P=0.03) and rotavirus (P=0.03), but didnot change the prevalence of C. parvum and coronavirus.

     

  3. RFC-fed calves had numerically higher body weight at 48 days of age compared to control calves. On average, the RFC-fed calves gained 4 pounds more than calves in the control group.

 

Ultimately, RFCs improved some gut health parameters, which led to numerical improvement of growth and performance in preweaned dairy calves. Keep in mind, though, it appears that the ability of RFCs to protect young dairy calves from developing severe diarrhea likely depends on factors—such as specific pathogen species and management strategies—found on individual farms.

  

1 Lean IJ., Santos JEP, Block E, Golder H. 2018. Effects of prepartum dietary cation anion difference intake on production and health of dairy cows: A meta-analysis. J. Dairy Sci. (submitted)

2 Santos JEP, Lean IJ, Golder H, Block E. 2018. Meta-analysis of the effects of prepartum dietary cation-anion difference on performance and health of dairy. J. Dairy Sci. (submitted)

3 Zimpel R, Poindexter MB, Vieira-Neto A, Block E, Nelson CD, Staples CR, Thatcher WW, Santos JEP. 2018. Effect of dietary cation-anion difference (DCAD) on acid-base status and dry matter intake in dry cows. J. Dairy Sci. (submitted)

4 Data shown here are part of a larger trial that was presented at the 2017 American Association of Bovine Practitioners Annual Meeting in Omaha, Nebraska, September 14 – 16, 2017.

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