Forage Quality Could Impact Cow Performance

LEXINGTON, KY.
   The wet spring last 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 re-productive 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 last 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 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.
   Late cut hay is lower in protein and is less digestible leading to less energy available to the animal. The low protein and lower digestibility of this hay also negatively impacts forage intake. This can lead to lactating cows being in a severe negative energy balance resulting in excessive body tissue mobilization to support nutritional needs. The loss of body condition can negatively impact reproduction costing the operation in the long term.
   To ensure the livestock are receiving an adequately balanced diet, producers should sample their hay and have it analyzed for nutrient content. This information is then used to develop a strategic supplementation strategy for cattle. Their nutritional requirements at different stages of production must be taken into account. In other words, dry, non-lactating bred cows in the mid-trimester of gestation will have lower nutritional needs than cows 60 days from calving in which rapid fetal growth is occurring. Forage analysis allows ranchers to more efficiently match hay quality to the nutrient needs of the cows.
   Producers that wish to utilize their forage analysis in developing a supplementation strategy should visit http://apps.ca.uky.edu/forage-supplement-tool/ by searching the internet using the key-words Kentucky Forage Tool. This simple web program allows a producer to enter a few pieces of information from their hay analysis, select the stage of production the cows are in along with various supplements to arrive at a supplementation program. It was developed to help producers utilize their hay analysis rather than simply look at the paper and toss it in a drawer. Producers are still encouraged to contact their nutritionist or county Extension agent for assistance in designing supplement programs. This tool will, however, get a cow-calf operator start-ed down the right track. Stay warm and supplement smart this winter. ∆
DR. JEFF LEHMKUHLER: Extension Beef Specialist, University of Kentucky