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Use improved nutrition to enhance immune function, fertility

Joel Pankowski for Progressive Dairyman Published on 24 February 2016

Dairy cow fertility has improved significantly over the past 10 to 15 years. Recent USDA data show that on most farms, 21-day pregnancy rates are on the rise, with many herds achieving 20 percent or better on a regular basis.

That’s great news because it wasn’t long ago when it was common for pregnancy rates to languish around 12 to 14 percent.

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Not only does this improved reproductive performance mean improved productivity for the herd, it has significant implications for the financial performance for your dairy.

Data show that increasing pregnancy rate from 15 to 25 percent results in an increase of $40 to $60 per cow, depending on feed cost, milk price and other economic factors.

Many factors are responsible for better reproductive performance on dairies, including improved reproductive management with implementation of estrous and ovulation synchronization protocols along with improved transition period management and a greater focus on health and fertility traits during sire selection for A.I.

These considerations, while important and noteworthy, provide optimal results when underpinned with a strong nutritional foundation. The value of enhanced nutrition programs that use targeted strategies to foster immune system function so cows are healthier in all facets of life cannot be underscored enough.

Health implications

As researchers, nutritionists, veterinarians and producers learn more about immune function, it’s become apparent that this is an area where improved nutrition management can achieve excellent results.

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When proper nutritional support enhances a properly functioning immune system, transition cows are less likely to develop clinical or subclinical diseases, particularly those caused by infectious agents. This also helps prevent the cascade of inter-related health events that can derail cow performance on every level.

For instance, researchers at the University of Florida have noted the cumulative effects of subclinical hypocalcemia on secondary transition health disorders and management challenges. They found that cows with subclinical hypocalcemia were more likely to have:

  • A 3.2X increased risk of metritis

  • A 2.4X increased risk of postpartum fever

  • Increased postfresh concentrations of blood beta-hydroxybutyrate (BHBA), the ketone body most commonly used to diagnose ketosis and subclinical ketosis (1 versus 0.7 mmol per L)

  • Longer median days open (124 versus 109 days)

Additional research has found that elevated concentrations of non-esterified fatty acid and BHBA around the time of calving are predictive for subsequent clinical mastitis and the development of displaced abomasum, clinical ketosis, metritis and retained placenta.

Finally, data from the University of Georgia show that days open increased by 33 days for cows diagnosed with metritis. Plus, pregnancy rates for these cows dropped by 4.5 percentage points as compared to pregnancy rates for healthy cows.

Role of essential fatty acids

Several nutritional strategies have been proposed to improve reproduction of dairy cattle with no detrimental effect on milk production performance, explains José Santos, University of Florida professor of animal science.

“Maximizing dry matter intake during the transition period, minimizing the incidence of transition period problems, adding supplemental fat to diets and manipulating the fatty acid content of fat sources are expected to benefit reproduction in dairy cattle,” he adds.

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An excellent way to boost cow health and immunity during the transition period is with scientifically proven feed ingredients that include essential fatty acids (EFAs).

EFAs are essential for cow health and productivity; they cannot be synthesized by the animal and must be provided by the diet. When included in rations in explicit combination, EFAs can result in increased gains in transition performance and overall productivity, allowing cows to perform at increased levels.

For instance, EFAs, specifically omega-3 (18:3 linolenic acid) and omega-6 (18:2 linoleic acid) fatty acids, serve important functions related to dairy cows’ reproductive health and performance.

These omega fatty acids:

  • Support the production of specific reproductive hormones, especially prostaglandins, which influences pregnancy maintenance.

  • Linoleic acids aid in prostaglandin F2a production, which has roles in ovulation corpus luteum regression, leading to a subsequent estrus cycle.

“In our studies, we’ve found that manipulating omega-3 and omega-6 in the diet influenced lactation performance and fertility,” notes Santos. “The inclusion of omega-3 and omega-6 resulted in greater yields of milk and milk components and improved pregnancy per A.I.

The benefits to fertility were observed primarily because of reduced pregnancy loss in the first 60 days of gestation.”

However, achieving these benefits can be challenging as cows may not consume enough EFAs through commodity feed sources typically included in the ration.

While several feeds, like cottonseeds and whole soybeans, are rich in linoleic acid, they are often altered in the rumen through biohydrogenation, making them unavailable in their original form and useless to meet daily nutrition requirements for those EFAs.

EFAs in action

In a series of on-farm trials conducted across the country under different management conditions, these specific EFAs used in combination:

1. Lowered BHBA levels, resulting in lower incidence of metabolic disorders

2. Lowered first linear somatic cell score for each herd

3. Reduced embryonic death

4. Increased pregnancy and conception rates

Pregnancy rate improvement ranged from 7 to 9 percent increases, and herd conception rates rose from 7 percent to as much as 15 percent.

5. Improved first milk weights for dairies that tracked this parameter

These results show a direct correlation to a stronger immune system, which helps reduce incidence of disease and metabolic challenges. These healthier cows are better able to perform in virtually every measurable management metric.

Therefore, for optimum results, think of reproductive management in a more holistic fashion. Success usually requires more strategy than simply tweaking a synchronization protocol.

True reproductive achievement is built on a firm nutritional foundation that’s based on scientifically proven ingredients and principles, then interwoven with the tools and strategies needed to get the job done.  PD

Joel Pankowski
  • Joel Pankowski

  • Manager - Technical Services
  • Arm & Hammer - Animal Nutrition
  • Email Joel Pankowski

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