Failing to stock up enough winter feed can leave producers in the cold. Glenn Selk, Oklahoma State University emeritus extension animal scientist, looks at how cows utilize forage and their intake to determine winter feed needs.
The key factor in this calculation?
Forage quality. Because cattle can more easily meet feed requirements from forages that offer more nutrients, they often eat more.
“Cows can consume a larger quantity of higher quality forages,” Selk says. “Higher quality forages are fermented more rapidly in the rumen, leaving a void that the animal can refill with additional forage.”
To better explain this intake boost, Selk points out that cattle consume around 1.5 percent of their body weight (on a dry matter basis) per day in low-quality forages (under 6 percent crude protein). Grass hays above 8 percent crude protein are consumed at around 2 percent, and excellent forages, such as alfalfa, silages, or good pasture are often consumed at around 2.5 percent.
“The combination of increased nutrient content and increased forage intake makes high-quality forage very valuable to the animal and the producer,” Selk says.
Using these figures, producers are better able to gauge how much hay is necessary for winter feeding. Selk walks through an example using 1,200-pound spring-calving cows and good grass hay that tested 8 percent crude protein. Using these values above, the cows will most likely be eating 2 percent of their body weight, or 24 pounds, based on 100 percent dry matter. However, Selk adds that grass hay frequently ranges from 7 to 10 percent moisture. This means that hay may only be 92 percent dry matter with 8 percent moisture; thus, cows will most likely consume closer to 26 pounds per day on an “as-fed” basis.
“Unfortunately, we also have to consider hay wastage when feeding big round bales. Hay wastage is difficult to estimate but generally has been found to be from 6 to 20 percent or more,” Selk says.
In the same example, Selk states that with an assumed 15 percent wastage, each cow must receive roughly 30 pounds of grass hay each day. In addition, while cows early in lactation may weigh 100 pounds less, Selk notes that they will be able to consume about 2.6 percent of their body weight, or 36 pounds of hay per cow per day.
“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 says.