manipulating the feeding program
Introduction to Nutrient Grid Adjustments
This session continues from Part 1 by focusing on modifying and refining nutrient grids. The goal is to correctly balance rations for calves by adjusting feed composition and observing how those changes affect nutrient intake over time.
Editing Feed Composition: Grain
The demonstration begins with the grain portion of the diet. Default feed values are loaded, and the process for converting “as-fed” nutrient values to a dry matter basis is explained. This involves:
- Right-clicking on a cell in the grid.
- Using the built-in calculator to convert as-fed to dry matter (DM) basis.
- Copying and pasting the corrected value into the nutrient table.
Example conversions include changing a feed with 14% protein and 90% DM to 15.56% on a dry matter basis. For a 3% nutrient, the adjusted value is 3.33%. Unnecessary nutrients like arginine and histidine are removed to simplify the table, while key nutrients like calcium and phosphorus are retained.
Configuring the Grain Feeding Program
After adjusting nutrient values, the feeding program is set up:
- Step definitions determine when each feed is introduced and withdrawn.
- Transition periods (ramps) are used to represent gradual changes.
- Limits are placed on feed quantities — e.g., no more than 3 kg of starter grain per day.
This allows the nutrient grid to simulate real-world feeding schedules effectively.
Switching Forages: From Sorghum Hay to Wheat Straw
Next, the forage section is updated. The default forage, sorghum hay, is replaced with wheat straw, which has higher fiber content (75% NDF). The process includes:
- Selecting the new forage type.
- Updating nutrient values manually or through the calculator.
- Correcting unrealistic default intake levels (e.g., changing from 100% forage intake to 8%).
This reflects more accurate intake for young calves and ensures the diet model aligns with on-farm feeding practices.
Updating Liquid Feeds: Colostrum, Transition Milk, Milk Replacer
The liquid feed section is revised to represent a common 24/18 milk replacer. Key steps include:
- Converting nutrient values to dry matter basis using the calculator.
- Deleting unnecessary nutrients to reduce clutter.
- Entering only relevant feeds: colostrum, transition milk, and milk replacer.
The speaker ensures these feeds are accurately reflected in the nutrient grid.
Structuring the Liquid Feeding Program
Finally, the liquid feeding schedule is customized:
- Colostrum and transition milk are offered in the first few days.
- Milk replacer begins at 650 grams per day and ramps up to 800 grams before tapering to 400 grams during weaning.
- The entire program is spread over five steps, covering different ages.
This staged approach aligns feed delivery with calf developmental stages and nutrient requirements.
Conclusion
Throughout the session, the nutrient grid proves to be a powerful tool for balancing rations by:
- Adjusting feed composition.
- Modeling feeding schedules.
- Visualizing nutrient intake over time.
With careful configuration, it allows for highly tailored feeding programs that reflect both biological needs and practical limitations.