Winter feeding is a very impactful practice for livestock producers utilizing cool season grasses in Appalachian, the Northeast and the Midwest regions.
It can have an influence on livestock performance throughout the winter and well into the following spring.
I will focus on the factors that cause hay nutrient degradation — some can be lowered, others are just part of the transition from a fresh crop to a preserved feed source.
Cool season grasses
Most of us utilize cool season grasses and legumes in the hay and pasture fields in eastern Ohio.
When cool season grasses sense cold, frost-producing temperatures, they tend to go dormant for the winter.
Therefore, in order to maintain the use of grasses as a feed source for livestock, we preserve the grasses by drying them and baling them up for winter feeding — another option is a dedicated pasture for stockpile grazing during the winter months.
However, for long-term feeding, hay usage is one of the most popular methods of winter available feed.
This is a great strategy because the grass just won’t grow when the temperatures fall in the lower 30s for an extended amount of time. And the sun makes its appearance less and less as we transition into December to compound the problem for forage growth.
An important thing to realize is that grass, much like vegetables, decrease in nutritional value when preserved. The key point to understand is that there will be a loss of dry matter (DM) and quality when making hay.
Even if the most ideal conditions are met during the cutting, curing, and baling, processes the quality of the hay will be diminished compared to the starting grass/legume material.
Forage harvest loss
The forage harvest loss can be up to 25 percent of dry matter through mechanical harvesting alone. What this means is that hay will never be as abundant and nutrient-rich as the forage was at the point of cutting.
When the grass is cut at 80 percent moisture, the grass is still chemically active and will utilize some of its stored sugars for metabolic activity as it dries.
Not to mention that the microbes present will also assist in the breakdown of the cut material until the preservation conditions are met.
On average you want to have hay preserved at less than 20 percent moisture. To be more specific:
- Small squares should be 20 percent or less; large round, 18 percent or less; and large squares, 16 percent.
- A forage test analysis will give you the percentage of moisture present in a bale.
- The approximate 2-3 days of curing the hay to bring that moisture level down as the plant is metabolizing energy and the microbes are breaking down the sugars and proteins, all contribute to the quality degradation and dry matter losses in creating the hay bale.
- Most of the nutrients will be preserved when the forages in the hay dry down to below 20 percent moisture, but there is still a slight loss even at storage.
- A good rule of thumb is that you should expect a 1 percent DM loss per 1 percent decrease of moisture even after baling.
Soil test for quality
To maximize the nutritional concentration of the forages used to make the hay, we need to maximize the grass quality at the start, and make the transition to the preserved state with the minimum amount of nutrient degradation.
The quality of the hay that is stored in your barn right now or possibly covered out on the field, all began at harvest. A field that has sufficient nutrients for grass/legume production will maximize the quality of the starting material.
To do this, a soil test is highly recommended so that the chemistry or pH of the soil is known.
Knowing the actual pH and cation exchange capacity (CEC) of your soil will allow you to calculate the amount of lime or sulfur to apply to the land.
Amending with the adequate amount of lime to raise the pH, or sulfur to lower it, will allow the forages to maximize the nutrients already available.
Lucky for us, most soil testing laboratories will calculate this number and it will appear on our soil test results form.
In my opinion, adjusting the pH of the soil is one of the most important interventions to improve crop growing conditions. This is usually done in the fall, but if the conditions are right can also be done late fall/early winter.
If adequate macronutrients are also available and your stand is full and weed free, chances are the quality of the starting forage is excellent if harvested at the proper time.
Harvest time is very important because as the plant matures and progresses to the reproductive stage, the lignin content increases and that binds up digestible sugars and proteins.
Lignin is a polymer compound that gives the plant rigidity and protection from pathogens. This compound can also get in the way of the carbohydrates/sugars and proteins stored in the plant that ruminant animals use as energy.
These digestible nutrients and proteins are what is used for the total digestible nutrients (TDN) calculation of the forage.
TDN is a good indicator of quality because it takes into account both the non-structural, digestible carbohydrates/sugars and the available protein of that forage available to the animal.
Neutral Detergent Fiber (NDF) is a measure of the indigestible fiber in the feed. These components are: hemicellulose, cellulose and lignin.
Remember, lignin lowers quality; think of lignin as a “cement” that causes the cellulose and proteins to be bound up and unavailable for the animal as it digests the material in its rumen.
Remember also that lignin increases as plants mature and especially when plants transition to a reproductive state (flowering).
A high TDN and low NDF will usually provide a higher quality forage.
Protein percentage is also important but remember that protein abundance and TDN are typically correlated.
Take the following guidelines into consideration:
- A high quality hay forage will typically have a TDN of 55 percent or greater accompanied by a crude protein level of 12 percent or greater with an NDF value of 40 percent or less.
- A poor quality hay will typically have a TDN of 45 percent or lower and a crude protein level below 6 percent, with an NDF value of 60 percent or greater.
Winter time is unfortunately one of the most energy demanding times for livestock, and is also when forage quality is at its lowest in the hay bale due to the losses discussed above.
That is why it is a good idea to understand what constitutes high and low quality forages to best decide the class of livestock and when to feed that livestock different qualities of hay for best management strategies.
When temperatures are below 20 F, beef cattle even with a heavy winter coat will start shivering and expend more energy. This means that the animal will have a greater nutritional requirement for basic maintenance.
When the animal’s coat is wet, that temperature can be as high as 60 F and induce shivering that will burn up more of the animal’s energy.
It is also important to consider the body condition score (BCS) of the animal. As the BCS score of an animal increases it has greater insulation from the elements, consequently it will burn less energy for warmth.
A higher quality forage will help maintain that animal’s weight during these critical temperatures.
Body score and calving
Research shows that a cow will come into heat sooner and be most fertile with a BCS of 5, 6 or 7. When beef cattle have a BCS of 4 or lower, they are more difficult to get bred.
If a cow calves with a BCS score of 4 or lower, it could take up to 80 days or greater for her to go back into heat.
Conversely, if she calves with a BCS of 6, she will likely come back into heat in approximately 50 days.
This is important because the maintenance of that cow in the winter will increase the speed and likelihood of getting her rebred after calving.
Once that cow has calved, her nutrient requirement will also increase due to the milk production, and putting weight on her will become even more difficult.
That is why it is important to help a pregnant cow maintain condition during the winter, especially if she will calve in February or March.
Tying it all together
Livestock nutrition is at its highest demand in the winter, and that is typically when the forages used for feed (hay) are at their lowest quality.
Using your higher quality hay on the class of livestock that have highest nutrient requirement during the winter months will give you an advantage in the spring, when it comes time to calve and have that cow rebred.
That cow will potentially produce more milk and go back in heat faster with a good body condition score coming out of winter.
Knowing the quality of the hay you have stored for the winter will allow you to manage your livestock and maintain their increased nutrient requirements during critical temperatures in the winter time, and also maintain a good BCS at calving.
Most extension offices throughout the state have hay probes available to lend out to farmers. The Extension Educators in these offices will gladly show farmers how to use these tools.
I have two in my office due to the increased trend of using forage analysis as a management tool on the farm.
Again, forage analysis will allow you to optimize the nutrients fed to your animals; this in turn can lead to increased breeding success rates following the winter, hay-feeding season.