Don’t Wait To Supplement

– Dr. Jeff Lehmkuhler, Associate Extension Professor, Beef Extension Specialist, University of Kentucky

The impacts of the fall drought conditions can be seen in some of our cow herds across the state.  Cows are lower in body condition as a result of the grass shortage.  Fall vegetative fescue grass will often be in the low 60’s on TDN and mid-teens for crude protein, much higher in quality than our average hay.  The lack of this fall forage growth will necessitate some early intervention.

Many of the hay samples that I’ve seen this year are lower in energy than normal due to the wet spring leading to over mature forage at harvest.  Surprisingly, the protein levels have been decent in many of the hay samples.  Knowing the energy and protein levels, one can develop a supplement program for your herd.  Step 1 test your hay and find out the nutrient content.  Your local Extension office can assist you with this process.

Spring calving cows that have just been weaned will not have the higher plane of nutrition from fall grass this year.  Cows will not recover body condition as quickly since lower quality hay is being fed early this winter.  To increase the body condition score of a beef cow from a 4 to a 5, an additional 249 Mcal is needed.  To achieve this in a 90-day window, the additional energy intake needed is approximately 2.8 additional Mcal/day which is about a 20% increase in maintenance energy needs for that beef cow in mid-gestation.

The maintenance energy needs for a cow is about 12.5 Mcal during mid-gestation.  Average fescue hay will often just meet maintenance requirements.  To increase the energy needed to gain condition as described above, one would need to supplement the cow.  Corn may be the most cost effective energy source this winter. The recent Beef NRC lists corn at 2.17 Mcal/kg meaning it would require 1.3 kg or 3 lbs of supplemental corn daily over a 90-day period to increase the body condition from 4 to 5.  Delaying supplementation to late gestation may require higher supplementation levels.  Nutritional needs increase in late gestation to support fetal development and often our forage alone will not meet the energy needs of cows during late gestation.

As with all production systems, there will be differences in what one predicts on paper and what is realized in the field.  Therefore, cattle managers need to routinely monitor the condition of the cows and make adjustments to the feeding program.  Target body condition scores would be a 5 for cows and 6 for heifers at calving to ensure a greater probability of them cycling when the bulls are turned in.  For assistance with hay testing and developing a feeding program, visit with your county Extension agent or nutritionist.