NASCalf Demo – Early Weaning
Hello and welcome to NASCalf. In this demonstration, we’ll set up a feeding program typical of early-weaning systems, where calves are fed a fixed amount of milk replacer and weaned between five and six weeks of age. Let’s get started.
We’ll begin by opening NASCalf and clicking on the Performance page. This gives us a high-level view of predicted growth rates, average daily gain, intake, and feeding costs for the program we’re building.
To set up an early-weaning liquid program, we’ll start with Composition. Here, we’ll define three liquid feeds: colostrum, transition milk, and milk replacer. In this example, we’ll select a simple 20:20 milk replacer formulation, representative of products commonly used in early weaning programs.
Because nutrients are entered on a dry matter basis, we’ll adjust protein and fat accordingly. With a dry matter of 95%, 20% protein becomes 21.05% on a dry matter basis. I can paste that value directly into the cell and repeat the same calculation for fat. We’ll calculate ash the same way. Since we’re not interested in fiber fractions like ADF, NDF, starch, or lignin, I’ll click on those column headers to hide them.
I do want to see calcium and phosphorus, so I’ll right-click on any column header, review the hidden nutrients, and re-enable calcium and phosphorus. Now we can see the full liquid composition. The colostrum used here is about 24 Brix, slightly higher than the typical 22 Brix, which increases dry matter, protein, and fat accordingly.
Next, we’ll move to the Feeding Program. I can do this either by clicking the feeding program box or by selecting it from the menu. In this example, we’ll have four feeding periods: one for colostrum, one for transition milk, and two for milk replacer. We’ll feed the milk replacer at a full rate initially, then reduce it by half during the final days before weaning.
Since we only need four periods, I’ll reduce the total number of feeding periods to four. During day one, calves receive six liters of colostrum—four liters at the first feeding and two liters twelve hours later. Period two covers day two, when calves receive four liters of transition milk. Beginning on day three, we introduce milk replacer.
From day three through day 42, calves receive 680 grams of milk replacer powder per day. The program automatically calculates the start of period four as day 43. From day 43 through day 49, we reduce the milk replacer to 340 grams per day. This creates a simple early-weaning program, with calves fully weaned at seven weeks of age.
On the performance screen, we can see total liquid intake is about 30 kilograms of dry matter from birth through two months. No liquid is fed during the second two months of the simulation. NASCALF uses this milk intake to estimate dry feed intake from grain and forage.
Now let’s move to the Grain Program. Here, we’re feeding a starter and a grower. I’ll set the starter price at $450 per metric ton and the grower at $300 per metric ton. Starter feeding begins on day three and ends on day 60, while the grower begins on day 50. That creates a 10-day overlap where both feeds are offered, and NASCalf assumes they’re fed as a 50:50 blend—an easy way to manage a starter-to-grower transition.
Next, we’ll look at the Forage Program. In this case, we’re feeding sorghum hay priced at $150 per metric ton. Forage is introduced on day 35 and offered through the end of the simulation. I’ll assume that forage makes up about 8% of total dry feed intake and enter that value here. When we view the feeding program values, we can confirm the forage composition—about 10% protein, 2% fat, and 8.5% ash on a dry matter basis, which is reasonable for this forage.
We can also review grain composition here. The starter is about 20% protein and 3.7% fat on a dry matter basis. Any of these values can be adjusted directly in the grid, just as we did with the liquid feeds.
Once liquid, grain, and forage inputs are complete, we’ll double-check the Calf Information. Here, I’ll adjust birth body weight and set mature body weight to 650 kilograms. Weaning occurs on day 49, so I’ll set a target gain of 0.7 kilograms per day from birth to weaning, and 0.9 kilograms per day after weaning. We’ll leave scours and temperature effects unchanged for now; those are covered in other demonstrations.
After clicking OK, we can review the results. Calves begin at 40 kilograms and reach about 125 kilograms by four months of age. Average daily gain is just under 500 grams per day during the first two months, then increases to about 900 grams per day from two to four months, for an overall average of roughly 700 grams per day.
Looking at weaning, calves are removed from liquid feed on day 49. However, the optimal weaning day—based on cumulative NFC intake of 15 kilograms—occurs on day 56. This is a biologically based indicator of weaning readiness. Industry-standard weaning, based on starter intake criteria, occurs earlier, around day 44. Those criteria can be adjusted under the standard weaning settings—for example, requiring calves to consume 1.5 kilograms of starter for three consecutive days.
In this simulation, calves double their birth body weight at about day 78, which is later than the commonly recommended target of doubling by two months of age. Total feed cost, feed efficiency, liquid intake, and dry feed intake are summarized at the bottom of the performance screen.
The Scientific screen provides deeper insight into nutrient adequacy. For example, at days 14 and 28, metabolizable protein intake is below the target needed to support our chosen growth rate of 700 grams per day. This shows that a 20:20 milk replacer does not supply enough metabolizable protein to meet that goal—an important takeaway from this example.
Finally, the graph on the right summarizes the feeding program visually. We see colostrum on day one, followed by milk replacer until just before weaning. Grain intake increases rapidly as calves approach weaning, reaching about 800 grams per day by day 42. Forage intake begins on day 35 and represents about 8% of total dry feed intake. Body weight is shown alongside the target weight curve, making it easy to see when calves are meeting—or falling short of—their growth targets.
That wraps up this demonstration of an early-weaning feeding program in NASCalf. I hope you found it useful. Be sure to check out other demonstrations in the knowledge base to learn how to get the most out of the program. Thanks for watching.
