by Sally Colby
During a drought, farmers hope for rain. When there’s too much rain, farmers wish they could just turn off the spigot.
“In drier conditions, people can get on the fields,” said David Balbian, Cornell Cooperative Extension regional dairy management specialist. “The fiber digestibility is typically better. In dry conditions, we don’t get a lot of feed, but we do get high quality because the lack of moisture reduces the lignin content in the plant, which increases fiber digestibility.”
But it hasn’t been dry, and weather conditions this season have been challenging. Balbian stressed the fact that each farm is different when it comes to rainfall patterns, soil types and related factors. “It’s hard to make a blanket statement,” he said, “but it’s been quite wet. By the time fields dry out, it rains again.”
Wet weather influences farms differently based on a number of factors, including soil conditions. “Some farms have well-drained soils, and it’s amazing what some have gotten done,” said Balbian. “A little corn planted, some hay crop harvested. But I’ve also seen some hay fields with ruts where people tried to get in and gave up. When we get a stretch of three to five days of no rain and consistent temperature, some fields quickly dry out. But it’s very farm specific.”
Ideally, forage is harvested on time, regrowth is rapid and second cutting is on time. Over the season, especially in years with well-timed moisture, the result is ample good quality feed. But on many farms, first cutting is still standing, turning into bedding, and second cutting isn’t even a thought. Balbian said many farms with forage stands greater than 50% grass are quickly becoming poor quality for milk production.
“What makes it challenging is the quality of 100% grass fields because grass quality goes downhill twice as fast as alfalfa,” said Balbian. “If you’re going to feed grass to lactating cows, it should be harvested first. If you’re late, you get hit twice as hard as with alfalfa.”
In the past, alfalfa was typically harvested first. “At that time, we didn’t realize the value of good quality grass for lactating cows and we gravitated toward alfalfa,” said Balbian. “Part of that was because alfalfa was ready later in spring and the quality of alfalfa declines at a much slower rate – about half the rate of grass.” Balbian also noted that corn wasn’t planted as early – the typical process was to plant corn, harvest alfalfa, then harvest grass for dry cows or heifers, or for bedding. “Now, we’re saying if you can get some good quality hay crop, which you need for economical milk production, harvest that first. Then go in and plant corn afterwards, even though corn will have to be a shorter season variety.”
First cutting typically results in about 50% of the yield for the year. “This year, it’s probably going to be more than that,” said Balbian. “But a lot of that is going to be poor quality. In some cases, we’re going to be short one cutting because the first cutting is harvested so late.”
In a wet year, part of the dilemma is deciding whether to harvest forage when the weather prediction shows sufficient drying days rather than when forage is at peak quality. “You don’t want to go in so early that there isn’t enough to make it worthwhile,” said Balbian. “Although people will say ‘This is the way it was done 30 to 40 years ago,’ our data is pretty good.” Balbian added that even with less volume harvested, there’s satisfaction in finishing sooner and having good-quality feed to show for it.
Another wet year challenge is getting corn in the ground. Although farmers select varieties based on a “typical” growing season in their area as well as feed requirements, the problem is that seed is already purchased. “You take a hit on yield when you’re planting late with a shorter season variety,” said Balbian. “Although the shorter season varieties have gotten better in yield, you’re going to lose less by doing that than by harvesting your hay crop late from the standpoint of quality.” Balbian added that feeding poor quality forage means having to feed more grain, and production will never be as high as with higher quality forage. “It puts a lid on the ability of cows to consume large quantities of feed, how much energy they’re going to get from it and how much milk they’ll produce,” he said.
Balbian said most dairies anticipate feeding corn silage from the previous year until Christmas or early the following year. “Ideally, we like to let the new crop ferment well,” he said, adding that every farm situation is different. “Over the years, we’ve seen cows make the transition to new crop corn much better when they go from previous year’s corn to new crop corn that has a chance to ferment well for three or four months instead of going into green corn or corn that’s only had a few weeks to ferment.”
This season, farmers may have to rely more on their herd nutritionist when adjusting rations to minimize jolts to the milking herd. “Some have traded their long-season corn for shorter season varieties,” said Balbian. “We’ve had years with these conditions, and those who wait until mid-June need an 85-day variety, but the short season corn is unavailable. You might be left short and have to plant a long season variety that doesn’t fill by harvest.”
In addition to considering NDF (neutral detergent fiber), Balbian said nutritionists are now looking at uNDF240 – the level of undigestible NDF at 240 hours. “Even though the feed doesn’t stay in her for 240 hours, researchers have figured out that 240 hours in the lab is a good predictor for fill factor – how much feed the cow will eat,” Balbian explained. “If there’s a high level of undigested NDF at 240 hours, cows are filled up and don’t want to eat as much. We know high producing cows eat a lot of feed, and if feedstuffs fill the cow up and she feels full, she eats two or three pounds less dry matter. Instead of eating 110 pounds of TMR, she eats 105 pounds.”
Balbian said although that may not seem like much difference, in a high group TMR, for every pound of DM the cow consumes (or doesn’t consume) and if all the nutrients go into milk production, every pound of DM is worth two to 2.5 pounds of milk. “If we lose DM intake by three pounds, we’re looking at six to seven and one-half pounds of daily milk production lost.”
While nutrition for dairy cattle has become more complex, more precise rations allow cows to produce at consistently high levels while minimizing metabolic issues.