Calves with Sam

Nutrients Available for Growth

(Estimates,  not research data)

All nutrients in the feed consumed by a calf end up being divided between maintenance and growth. Changes in ration (for example, weaning) and changing in housing (moving from individual to group pens for example) may change the total amount of nutrients available. 

I set up a data base for calves from 35 to 82 days of age. Using field experience with weaning calves and moving from individual to group pens I set rates of milk, calf starter grain, grower grain and hay on a daily basis. 

Based on analysis using the NRC calf growth simulation I was able to determine the amount of feed available for maintenance (thermoneutral environment) given two rations: 

1. Step-down weaning with limited hay

• Week 6 = 1/2 milk, ad lib. grain and water, individual pen
• Week 7 = no milk, ad lib. grain and water, individual pen
• Week 8 = ad lib. grain and water, group pen
• Week 9 = ad lib. grain and water, 1 pound hay per day, group pen
• Week 10 = ad lib. grain and water, 2 pounds hay per day, group pen
• Week 11 = ad lib. grain, water and hay

2. Step-down weaning with ad lib. hay

• Week 6 = 1/2 milk, ad lib. grain and water, individual pen
• Week 7 = no milk, ad lib. grain and water, individual pen 
• Week 8 = ad lib. grain, water and hay, group pen
• Weeks 9 - 11 = same as week 8

 Click here for the graph showing feed available for growth by ration.

Note the sharp drops each time there is a change in ration. And the big step down with the move from individual to group housing. 

The difference between gradual introduction of hay (blue line) and abrupt change to ad lib. hay reflects both the initial inability of the rumen to adequately digest hay and the displacement of grain by hay intake.