NASCalf Switches
Hello, and welcome to this NASCalf Knowledge Base video. In this video, we’ll explore the Settings options in NASCalf and show how these switches allow you to modify the calculations the model uses to predict intake and growth. Let’s take a look.
All settings are accessed from the Settings tab. Within this tab, there are two options: Switches and Palette. In this video, we’ll focus on the Switches. When you click on Switches, a new window opens that you can resize as needed. This window contains a series of checkboxes; each controlling a specific calculation or display option in the model.
Each switch is shown in a row with its name, a checkbox, and a brief description of its function. We’ll go through these switches in order.
The first switch is Use Targets. When this box is checked, NASCalf evaluates performance relative to the targets you’ve defined. These targets are displayed on the Performance screen in the row of summary boxes at the top. When targets are enabled, each box is color-coded: green indicates the result is within criterion of the target, yellow indicates it is within a second criterion, and red indicates it is a final criterion away from the target.
In this example, most targets are being met, but liquid intake is below target—we’re feeding about 50 kilograms instead of the target of 70—and dry matter intake from zero to four months is also below the target. Additional Knowledge Base articles explain how to set and adjust targets and how to change the criteria for the color coding. Clearing this checkbox simply turns off the color display.
The next switch is Show Body Weight. This controls the large graph on the right-hand side of both the Performance and Scientific screens. When this box is checked, the target body weight curve is displayed. If it’s unchecked, the target line is hidden and only the simulated body weight is shown. This allows you to easily compare actual predicted growth to target growth.
The next three switches—Gompertz, Polynomial, and Fixed—control how target average daily gain is calculated. Target ADG is critical because it determines the energy and protein requirements for growth in the NASCalf model.
The Gompertz option uses a classic Gompertz growth curve, which is widely used to model animal growth. From this curve, the model calculates target body weight and the corresponding average daily gain over time. These targets tend to be somewhat lower early in life and increase gradually.
The Polynomial option uses growth curves derived from Penn State University body weight data. The model calculates optimal body weights at each age and then determines the average daily gains needed to reach those targets. Like the Gompertz option, polynomial targets typically start lower and increase over the course of the simulation.
The Fixed option uses constant target average daily gains, with one value for pre-weaning and another for post-weaning. This approach is most similar to the traditional NASEM model, where growth targets are fixed rather than changing with age.
The next three switches relate to dry feed intake prediction. NASCalf offers three different intake equations.
The first is ISCAN DMI, based on the dry feed intake prediction equation published by Quigley and colleagues in 2021.
The second is ISNAS DMI, which uses the intake model from the NASEM Nutrient Requirements book.
The third option is based on an equation published by Silva and colleagues in 2019. That equation applies only to pre-weaned calves, so after weaning, NASCalf automatically reverts to the Quigley model.
You can select any of these three options, and the model will immediately recalculate intake and growth.
The next group of switches adjusts digestibility assumptions for liquid and dry feeds, based on published research.
The first two switches adjust liquid digestibility for energy and protein, using relationships reported by Quigley and colleagues in 2021. That work showed that digestibility of liquid feeds is lower during the first 30 days of life and gradually increases with age. When these switches are enabled, you can see small changes in the digestibility curves on the Scientific screen, particularly in the graphs showing liquid feed digestibility. These changes also affect predicted performance. In this example, final body weight declines from about 145 kilograms to 141 kilograms when both liquid energy and protein digestibility adjustments are applied. By default, these switches are turned off.
The next switch adjusts liquid protein digestibility for vegetable protein sources. If a milk replacer contains significant vegetable protein—indicated by higher crude fiber or NDF values—the model reduces protein digestibility, accordingly, using values from the feed composition.
The next two switches adjust dry feed digestibility for energy and protein, based on work published by Quigley and colleagues in 2020. These studies showed that digestibility of dry feed is lower early in life, before rumen development and before calves reach about 15 kilograms of cumulative NFC intake. When these switches are enabled, digestibility values can range from roughly 40% to 80%, depending on age and intake.
The Adjust MCP switch modifies the contribution of microbial crude protein. When enabled, microbial protein contribution increases with intake and age based on relationships described in the 2021 NASEM publication. If this box is unchecked, NASCalf uses a fixed rumen undegradable protein value instead.
The next switch limits dry matter intake based on NDF intake, capping intake at about 1% of body weight as NDF. This relationship comes from heifer research by Hoffman and colleagues. Because calf diets rarely reach this NDF level, enabling this switch usually has little effect.
The IsJersey switch increases the net energy requirement for maintenance by 10% for Jersey calves, based on research from Virginia Tech. Enabling this option increases maintenance energy requirements and affects predicted growth accordingly.
Finally, the Striped Pages switch controls the appearance of tables in reports. When checked, tables are displayed with alternating row shading. Clearing the box displays plain tables.
That concludes our overview of the Settings switches in NASCalf. These options allow you to tailor intake predictions, digestibility assumptions, and growth targets to better reflect your management system and research preferences.
Thanks for watching, and be sure to explore the other NASCalf Knowledge Base videos to learn more about how to get the most out of NASCalf.
