How much distillers to feed bred heifers?

Producer Question from 2010

Q:  On prairie hay, how much dried distillers can you feed bred heifers? We are running out of shelled corn and have distillers but don't want to run into large birth weight on the calves. (January 9, 2010)

A:  I assume that these heifers will calve for their first time this spring. Depends on the quality of the grass hay. If I use average values for the prairie hay, the heifers are likely deficient in both protein and energy as they get closer to calving. Right now they would need a diet that is about 58% TDN. Distillers would be an excellent choice in this situation because it is a good energy and protein source. In addition, because the majority of the diet will be hay, distillers will not have any negative impact on hay digestion. With this hay, I like distillers in the diet compared to corn.

I assume that the distillers is the dry distillers grains. Before calving, to get the diet to 58% TDN you would need to feed 2.5 lb/hd/da (they need 2.2 lb/hd/da on a dry matter basis and assumed that the distiller was 88%dry matter). Total intake of hay and distillers would be about 24 lb/hd/da as-fed. After calving using the same hay you would need feed 4.2 lb/hd/da (3.7 lb/hd/da dry matter and distillers 88% dry matter). Intake after calving would be 25 to 26 lb/hd/da as-fed. The lactating diet will be about 12% CP and 62% TDN.

I would not be concerned about impacting calf birth weight with nutrition. If these heifers are bred to light birth weight bulls, you have over half the battle addressed. Data would suggest that there is limited impact of nutrition on birth weight and the effect of nutrition on birth weight is interacting with weather (cold temperature). It hard to predict the weather.

To fine tune the diet, it would be nice to know the quality of the hay.

When feeding distillers, you will not need to supplement phosphorus. So get a byproduct mineral block and always supplement salt. Also, make sure all females have the opportunity to eat their share.

Dr. Rick Rasby, Professor of Animal Science
Animal Science, University of Nebraska–Lincoln, Lincoln, NE