We have been fortunate to have a surplus of forage in North Central Wisconsin so far this summer. The quality of much of the 1st cutting is not as good as other years, but it is forage nonetheless. I have spent some time studying MP heifer rations with mature quality hay and haylage. I think that to maintain the 2.25 pounds or more average daily gain that we are trying to achieve for our heifers, we need to reexamine our feeding strategies for a critical group of heifers on our farms, around 400 pounds. This is often the group that is being introduced to a higher forage ration.
I have been using metabolizable protein and energy to balance heifer diets for the last couple of years. The strategy has helped make feeding more efficient and higher quality protein sources critical, just like in lactating cow diets. The heifers on this type of program are responding with better ADG. Heifer rations have been traditionally balanced with crude protein and Net Energy of gain to achieve growth benchmarks. I thought it would be an interesting exercise to compare the 2 ration balancing methods with mature quality hay or haylage.
Before we compare, I want to state that I used the 2001 NCR requirements for 410 lb. heifers with a mature weight of 1458 lbs. ADG in this example is 2.25 lbs. These inputs required 8.8 pounds of DMI. The heifers are clean, dry, and the temperature averages 60 degrees.
The crude protein requirement for this heifer is 16%. The NEg requirement is 54.5 Mcal/cwt. If we balanced a diet to meet those criteria with mature haylage, this is what it would like:
|Mature Haylage||5.98 lbs/day|
|Cracked Corn||4.9 lbs/day|
|38% heifer pellet (no urea)||2.05 lbs /day|
This diet met protein and energy requirements, but is inadequate to maintain 2.25 lbs/day growth. The ME allowable ADG is only 1.91 lbs/day. The MP allowable ADG is only 1.91 lbs/day. In order to meet or exceed 2.25 lbs/day of growth, the ration should look like this:
|Mature Haylage||4.44 lbs/day|
|Cracked Corn||4.50 lbs/day|
|38% heifer pellet (no urea)||3.25 lbs /day|
The MP and ME balanced diet is now 19.86% crude protein and 57.62 Mcal/cwt. NEg, far exceeding the traditionally balanced diet. The crude protein in the grain mix needed to be 19%, not the 15% mix that the traditionally balanced diet had. Balancing for MP and ME shows that we cannot use crude protein as a benchmark for growth. We need to feed highly palatable, high quality, high protein mixes to our young heifers. Sample forages, and ask your consultant to use MP balancing for young heifers. They will pay you back with the growth and health you expect.
Animal Nutrition Manager