After last winter's myriad stories about hay and forage shortages across huge swaths of geography, several things became graphically clear to me.
First, the lack of real forage management is disastrous. From a personal standpoint, when other people were complaining about ruined pastures and hay shortages, near me and far away, I was wondering if I'd even get through my stockpiled forage. I bought more cattle and we kept grazing. When May turned out to be cold and rainy and my forage began to melt, I wished I had saved just a few round bales of prairie hay. But with the mix of thin new forage and fading old forage, we made it.
Throughout winter I was able to keep estimating my forage consumption by the day and by the acre, just as the smart people had taught me, and project it forward. It worked pretty well and I knew I had plenty to get past the end of May. In a normal year we would have been into really good grass growth by then.
However, one of the struggles I have -- and I believe everyone who actually calculates forage/hay tonnage and consumption has this difficulty -- is getting your estimates to match your real consumption. The scientific forage consumption data for cattle is pretty good, as nutritionists use it all the time, but a variety of things modify their actual behavior versus what the science says they are "supposed to do."
Glenn Selk, a retired animal scientist from Oklahoma State University, put out some numbers on hay just the other day I think are worth review. Before we get into those, however, let's talk about figuring up how much grazing you have. The simple way, as explained very clearly to me by Jaime Elizondo of Florida, is to take the daily consumption of dry forage by your herd at the beginning of winter (after dormancy) in acres, and project that forward. First you simply divide the daily acreage usage figure into the total number of acres of remaining forage.
Then the hard part begins. You must also estimate how your total supply of standing forage compares in density and height, therefore total tonnage, to the forage you're grazing at the time of your calculations. Then you'll need to figure some loss as winter progresses -- it depends on the year, right? Information from past years should help with this, but the more frequently you partition out forage through the winter, the more you're increasing grazing "efficiency" and the longer it will last.
Then you must add in hay consumption, if that's part of your operation. This is where I thought Selk's numbers useful.
For the record, I rolled out some late-cut prairie hay the other day to help improve a very poor area in one pasture, and with the cows shut on a narrow strip of forage they didn't want to eat, I got about 32-33 cow days per 4x6-foot bale, although I had estimated it would be a little higher than that.
Selk noted that cows can consume a larger quantity of higher-quality forages, likely because they are fermented more rapidly in the rumen, leaving a void that the animal can re-fill with additional forage. (Yes, we should all know that.)
He listed these consumption levels:
- Low-quality forages, below about 6% crude protein, will be consumed at about 1.5% of body weight on a dry matter basis per day.
- Higher-quality grass hays, above 8% crude protein, may be consumed at about 2.0% of body weight per day.
- Excellent forages such as good alfalfa, silages or green pasture may be consumed at the rate of 2.5% dry matter of body weight per day.
Here is Selk's example of how to figure hay consumption:
If you have 1,200-pound, pregnant spring-calving cows, and the grass hay quality is tested 8% crude protein, cows will voluntarily consume 2.0% of body weight, or 24 pounds per day. The 24 pounds is based on 100% dry matter. Grass hays will often be 7-10% moisture. If we assume that the hay is 92% dry matter or 8% moisture, then the cows will consume about 26 pounds per day on an "as-fed basis," Selk explains.
However, we also have to consider hay waste when feeding big round bales. Hay waste is difficult to estimate, but generally has been found to be from 6% to 20% or more, Selk recalled. For this example, he assumes 15% waste. This means about 30 pounds of grass hay must be hauled to the pasture for each cow each day that hay is expected to be the primary ingredient in the diet.
After calving and during early lactation, the cow may weigh 100 pounds less, but will be able to consume about 2.6% of her body weight in hay (dry matter basis). This would translate into 36 pounds of "as-fed" hay per 1,200-pound cow per day. In this calculation Selk again assumed 15% hay waste.
"Accurate knowledge of average cow size in your herd as well as the average weight of your big round bales becomes necessary to predict hay needs and hay feeding strategies," Selk said.
Waste is a point of view, I realize. The hay has nutrients that go back to the soil, either through the cattle or directly through the hay on the soil surface. Hay feeders produce different "waste" amounts, but rolling out the hay seems to me the ideal way to feed it. I see more and more trucks with hydraulic bale arms and roller spindles, so I think my point of view falls within a growing belief system. Too bad grazing management isn't spreading as quickly.
Don't forget to supply basic nutritional needs of your cattle according to their production class. For example, dry cows normally need about 8% protein to maintain body weight, while native prairie hay commonly has 4-6% protein. That means you need to make up the difference of 2-4%. Just one example.
There are many good online resources, and one of my favorites is Nutrient Requirements of Beef Cattle from Oklahoma State University.
Deciding at what time during the winter to feed hay can also be difficult. It should involve some thought and not just habit. Some people feed some of their hay early to stockpile more forage for the muddy times in spring when it's easier to move cattle than it is to move hay. Some folks, of course, must spend part of the winter depending entirely on hay because the snow gets too deep at some point most years to continue grazing.
Also, hopefully you know this, but well-managed consumption of standing forage is always cheaper than hay. Sometimes hay is a necessity, but it costs more.