Estimating cow herd feed inventory requirements

The simple answer is that 6-9 round bales are needed to feed a cow over the winter.   That’s one round bale of good quality hay per month.  Assuming the round bale of hay weighs 1200 pounds, then one round bale per month should meet a non-lactating, pregnant cow’s feed requirements when consuming 40 pounds of hay daily for 30 days. 

Grazing crop residue and swath grazing can reduce the number of round bales needed during the winter feeding season, but extended subzero weather can increase hay consumption and/or waste by 10-30%.  It’s always a good plan to have a few extra bales available when poor weather conditions exist.  Some managers will opt for 10% extra inventory while others secure a full extra year’s supply of hay inventory. Remember to include bulls and replacement heifers when estimating feed needs.

Early season 2016 hay production was diminished due to a lack of winter snow and minimal March and April rains, while late-season hay production was affected by too much rain.  Good quality hay may be in limited supply but other hays and straws are solid options, as long as you remember that rain damaged hay, straw and stover have reduced feed values and need supplementation.

Usually energy is the limiting factor in poor-quality hay rations. Corn silage is an excellent source of energy with production yields ranging from 10-25 ton per acre (depending on variety, fertility, soil, rain, etc.).  If extra feed energy is needed for wintering the cow herd, then 10 acres of 18 ton/acre corn silage should provide enough energy to feed 150 cows for one month when fed 18 pounds TDN per day.  As an energy substitute, 2 pounds of corn silage replaces 1 pound of hay.  (corn silage: 35% dry matter, 65% TDN DM; hay: 85% dry matter, 50% TDN DM).

Many co-product feeds are readily available in North Dakota. Distillers grains, wheat midds, barley malt sprout pellets, beet pulp, and tailings.  As an energy substitute, 0.4 pounds of dried distillers grains replaces 1 pound of hay (DDGS: 92% dry matter, 86% TDN DM).

Count your hay bales, be sure to test for quality, then supplement as needed. 

Karl Hoppe, Ph. D.
Area Extension Livestock Specialist