Dairy producers and nutritionists proactively seek ways to optimize diets for feed efficiency, enhance milk production and ensure the health and wellbeing of their herds. Achieving these goals can be challenging due to the complex interplay of nutrient flows and the dynamic nature of rumen fermentation.
The ability to predict sufficient nutrient supply to the rumen and rumen microbes can contribute to more confidence around diet formulation and lead to a more profitable cow. Nutrient balancing with isoacids in mind is a great way to achieve this.
Why Isoacids Matter in Dairy Nutrition
One of the lesser-known but essential nutrients in ruminant nutrition are branched-chain volatile fatty acids (BCVFAs), also known as isoacids. These compounds, produced from the degradation of branched-chain amino acids (BCAAs), are essential for the growth of fiber-digesting rumen bacteria and they can have a significant impact on the performance of animals fed forage diets.
Historical Context: From Early Research to Modern Models
The concept of isoacids as a necessary nutrient class for rumen bacteria is not novel. The industry has continued to research the importance and impact of isoacids in dairy nutrition for nearly half a century. Research completed over the last decade has reinforced our understanding of microbial demands for isoacids and shown how supplementation can improve dairy cow health and performance.
As the industry begins to recognize the importance of isoacid nutrition, the Cornell Net Carbohydrate and Protein System (CNCPS) v6.5.6 model now includes the consideration of isoacid balances in lactating diets.
What’s New in CNCPS v6.5.6
Understanding the updates made to the latest version of CNCPS can help nutritionists and producers predict the impact of three isoacid sources:
- Dietary protein degradation: The primary source of BCVFAs is dietary protein degradation. BCAAs are absorbed by sugar and starch degrading (classified as non-fiber carbohydrate [NFC] degrading) bacteria, converted to isoacids, and cross-fed to fibrolytic bacteria. The differential between BCAA use and need by NFC bacteria help to determine the available BCVFA supply for the fibrolytic bacteria that require these nutrients.
- Rumen bacterial turnover: A minor source (~10-15%) of total isoacids comes from microbial turnover within the rumen.
- External supplementation with Zinpro® IsoFerm®: When diet-based supply is insufficient, isoacids can be supplemented using Zinpro IsoFerm.
For all sources of isoacids, the CNCPS model will consider utilization efficiency based on the relationship between degradable protein and fermentable carbohydrates, where utilization rates are higher in diets low in degradable protein and/or high in fermentable carbohydrates. This is exacerbated further when the potential fermentable NDF level is greater than 14% of dietary dry matter.
Key Considerations When Evaluating Isoacid Balances
The updates to the CNCPS model provide an additional level of granularity around rumen fermentation and bacterial growth. Special consideration should be taken when evaluating these balances – certain feed and animal inputs will affect isoacid balances and predictions for supplementation to overcome these deficiencies. Keep these considerations top of mind as you begin to balance with isoacids:
Accurate Feed Inputs are Essential
The model’s predictive accuracy depends on robust feed analytics, especially NDF digestibility (NDFD) timepoints (12, 30, 120, and 240 for forages) and 7 hoursstarch digestibility values. Providing these digestibility inputs, particularly for forage ingredients, helps identify potential isoacid limitations in the rumen.
Understanding Dry Matter Intake: What the Model Doesn’t Tell You
The CNCPS does not account for the effect of isoacid supplementation on dry matter intake (DMI), and users of the software should know how isoacid supplementation impacts DMI. Research shows:
- Pre-partum isoacids increase DMI in the fresh period
- Whole-herd supplementation may reduce DMI, as animals in later lactation have lower DMI
- First-lactation heifers partition nutrients towards growth, demonstrating greater average daily gain
- Multiparous cows, who are closer to their mature size, show higher milk production
Don’t Neglect Degradable Protein
Isoacids are vital nutrients for certain populations of bacteria; however, the priority toward isoacids should not be at the expense of limiting rumen degradable protein (RDP) in the diet.
Most diets should maintain a true RDP (tRDP) of 185-215 g/kg of fCHO (fermentable carbohydrates) to maintain a properly functioning rumen environment. This does not account for the amino acid profiles of individual ingredients, which will impact isoacid balance predictions.
When to Expect Results
Model changes will predict an immediate shift in energy and protein status for the animal, but a perceived herd response will take time. Observable differences in fiber digestibility, bacterial growth and subsequent milk production can take up to three to four weeks from initial isoacid supplementation.
The Bigger Picture: What This Means for Dairy Nutrition
With the integration of CNCPS v6.5.6 into diet formulation software, nutritionists can now evaluate and formulate diets for isoacid balances and supplementation more effectively. The model provides insights into the availability of BCAA for isoacid utilization and suggests the appropriate amount to be supplemented to meet microbial demand if these nutrients are predicted to be deficient. Meeting these nutrient demands helps improve feed efficiency.
Balancing with isoacids and feeding Zinpro IsoFerm, producers and nutritionists can position cows to more easily adapt to seasonal and lactation changes while improving productivity. Research shows that isoacids can assist *multiple areas of performance, including:
- Better tolerance of Heat Stress with preserved feed efficiency and performance
- Transition Cows are better equipped to navigate the demands of early lactation when supported by improved protein and energy balance, stable body condition and improved liver function.
- *DMI decreased 2%
- *Feed Efficiency increased 5.5%
- *Milk Production increased 4.3%
*Average results across whole-herd. Individual results will vary based on parity and stage of lactation.
The updates in CNCPS v6.5.6 represent the next consideration in dairy nutrition, providing a more precise approach to diet formulation. By embracing this advancement and leveraging the benefits of isoacids, dairy producers can achieve better outcomes for their herds and stay ahead in the competitive landscape of dairy farming.
To begin incorporating Zinpro IsoFerm into your herd, contact our dairy team today.
