by Sally Colby
Although a group of dairy cattle isn’t typically referred to as a ‘mob,’ that’s what they are when they’re grazing a small section of highly nutritious pasture in a short amount of time.
USDA-ARS pasture researcher Dr. Kathy Soder says dairy farmers are asking a lot of questions about mob, or tall grazing, but there aren’t any firm answers. Soder and other researchers are working with farmers to determine the benefits of mob grazing.
“We were getting a lot of questions but didn’t have a good definition of it ourselves,” said Soder. “We talked with farmers who were, by self-description, mob-grazing, and asked what their definition was.” Soder noted the five farms involved in the study each have unique methods of mob grazing. One goal of the study is that the results of this preliminary study will help with funding of additional grazing research.
Forrest and Greg Stricker, who operate Spring Creek Farms, a five-generation family farm in Berks County, PA, are participating in the study. The Strickers have been operating the 400-acre farm as a certified organic dairy since 1999. Over the past several years, they’ve transitioned to intensive grazing.
The Strickers graze their milking herd of 140 cows with two bulls in a series of paddocks. “We have about 140,000 pounds of cow on about 3/4 of an acre,” said Forrest, describing the grazing strategy. “The pasture was fizzling out, and we wanted to so something so that the pastures would last longer and perform better. This pasture was established in the fall of 2010.”
The pasture mix includes alfalfa, which Forrest says will persist through summer on the farm’s shale ground. Other species include white clover, ryegrass and perennial rye grass. The paddock, which had been mob grazed in a 30-day rotation, was full of leafy, succulent growth that cattle devoured. “There’s a little too much legume in here,” said Forrest. “The grass has fizzled out and the legumes have taken over, but I think the grass will come back.”
In spring of 2011, the Strickers stopped feeding grain to the herd. “We wanted to get more energy out of the top of the grass,” said Forrest, comparing the level of maturity in the paddock to that of high-quality first-cut hay. “Cuttings would be every 30 to 35 days, and that’s when we have the best balance of energy and protein, and when we see the best animal performance.” The summer ration includes pasture for protein and molasses for energy.
Nutrition isn’t the only benefit of tall grazing. “We’ve seen fewer flies on the cows,” said Forrest. “We also see better animal condition and health, and milk production has held.” Forrest says the cattle are on pasture throughout the day, and will be provided with shade when temperature and humidity climb.
Greg Stricker says prior to switching to 100 percent grazing, the milking herd received six pounds of grain/day. On grass, the herd peaked at an average of 52 pounds/cow/day in early May. “We keep trying to refine the pasture program,” said Greg. “We hope that the changes we’ve made will keep production up.”
Greg keeps an eye on the cows throughout the day when they’re on pasture. “We try to leave a decent amount of leaf area so it can capture the sunlight and regrow faster,” he said, adding he carries litmus paper to catch urine in the field. “I like to see the pH at around 7 or 8 — when it hits 9, they’re getting too much protein.” If protein levels are too high, Greg feeds baleage or dry hay, or moves cows to a paddock that has more mature grass. However, desirable protein and energy levels can be maintained when cows graze the tops of plants rather than the entire plant. MUN levels were as high as 20 earlier in the season, but dropped back to around 12 with more mature grass.
At the beginning of the grazing season, cows are grazed on southern slope pastures. The herd is first grazed on fescues, which grow earlier and can take more grazing pressure. As the season progresses, cows graze north-facing pastures with different pasture species. Cows are moved every hour and a half to two hours throughout the day, depending on pasture species, time of day and how long they’ve grazed the previous paddock. “They’ll lie down after they eat, then when they start getting up to look for more feed, I’ll move them,” said Greg. “I backfence whenever I can to keep them off of the paddock they just grazed.”
“It’s very management-intensive to do mob grazing right,” said Forrest. “If we’re busy and can’t move cows every hour, we pre-mow, then the cows trample it in and we get the same effect as with mob grazing.
The Strickers estimate that the cost per day/cow for supplement (molasses) is about $1.25, which is close to what grain would cost. “One thing that triggered us to go no grain was the cost,” said Forrest. “Grain (organic) was $15 to $16/bushel, and it was hard to get.
Forrest is pleased with the body condition of the herd, although he was concerned that the cows were too thin in 2011. “Once the cows are off grain and on grass, the rumen bacteria change,” he said. “The whole system just works better.”
The final results of the grazing study will be available this fall from the Northeast Pasture Consortium at grazingguide.net
Grazing a mob
by Sally Colby