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Forage quality could impact cow performance

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By Rick Greenwell

This is information we received from Dr. Jeff Lehmkuhler, Extension Beef Specialist, University of Kentucky.  

Dr. Lehmkuhler has visited with some producers in our county and has worked with them on rations.  

These producers told me that their cattle looked better, not overly fat and are healthier.  

They credit their success with their cattle to him.

The wet spring this year resulted in several acres of hay that were cut and baled late.  

This can be problematic since much of our hay is derived from fescue and fescue-legume mix stands.  

The later the hay harvest, the more the plants advance in maturity from a vegetative stage, which is all leaf, to an advanced reproductive stage when the seeds are developed.  

The ideal time to harvest cool-season grass for hay from a yield and quality perspective is from boot stage (i.e., just prior to the flower emerging from the stem) to early flowering.  

Due to the excessive precipitation received this year, many fields were cut beyond this ideal time frame.  

Hay that was in the soft dough to fully ripened seed stage was harvested from several fields.  

The quality of hay at these later stages of maturity poses problems for our beef cattle, especially those with high nutritional needs such as lactating cows and growing calves.

The figure below is a plot of approximately 60 forage analysis from hay sampled in 2013.  

The lines represent the energy and protein needs for a cow in late gestation.  

Hay samples that are left of the vertical line require protein supplementation.  

Samples below the horizontal line are energy-deficient.  

Thus, those in the lower left quadrant are both energy- and protein-deficient while those in the upper right quadrant exceed both the energy and protein requirements.  

You should be able to see that many of the hay samples are adequate in protein but deficient in energy.  

Thus, in many instances, energy is first limiting during this phase of production while protein will likely be limiting along with energy as the cows start their lactations.