Wintertime bale feeding systems improve pasture compared to drylot systemsWritten by Natasha Wheeler
Sharing results from a two-year study, Western Beef Development Centre Research Scientist Bart Lardner compared three different winter feeding systems for pregnant cows.
“We wanted to evaluate traditional drylot pen feeding with bale processing and bale grazing,” noted Lardner.
Bale processing involves using equipment to break bales up into windrows for feeding, whereas bale grazing refers to leaving round bales out in the pasture in the fall and using portable electric fencing to manage grazing patterns.
“Some of the measures we looked at in this study were the impact of grazing systems on cow condition and performance, the changes in soil nutrient profile for phosphorous and nitrogen and the forage response of the winter grazing sites the following year,” Lardner explained.
In the study, 96 spring-calving beef cows were distributed into each of the three systems, with 32 cows per system. In one system, cows were assigned to the drylot from November through March and fed a forage-based ration of mixed hay.
“Our bale processing system was managed allocating one hay bale and one straw bale to those cows every three days to control utilization or wastage of the feed, as well as trying to distribute those nutrients evenly across that winter feeding site and to eliminate the cost of spreading manure,” he added.
In the bale grazing system, bales were set out in the fall, and cows were moved to allow for access to one hay bale and one straw bale every three days.
“We also applied raw manure from the drylot pen using a tractor and manure spreader at 30 tons to the acre. We applied 10 tons to the acre of a compost material from a previous experiment. We left one area of that pasture untouched, using it as a control as well,” he continued.
The feeding systems were located in a pasture of Russian wild rye that had not been managed for nutrients for five years.
“Looking at the effect of winter grazing systems on body weight change of the beef cows, there was no difference in body weight change in the first year,” Lardner noted.
In the second year, there were positive body weight changes across feeding systems, but no significant differences were recorded.
Looking at the soil nutrient profile, he comments, “We found there was no change in phosphorous levels in terms of pre- and post-grazing. The real interesting aspect here was the increase in soil inorganic nitrogen – both nitrate nitrogen and ammonium nitrogen.”
Soil samples revealed 2.5 to three times more soil inorganic nitrogen where cows had wintered and no increase where that manure was applied with equipment.
“Using a computer program, we looked at the concentration of nutrients in the bale graze and bale process trials as well. In the bale process, nitrogen was more evenly distributed across the winter grazing site because we were using the bale processing system to evenly distribute the feed, whereas most of that nitrogen concentration on the bale graze site was where the bales sat,” he explained.
Forage yields also increased where cows were fed by bale processing or bale grazing.
“There was a similar forage yield where the raw manure was applied with equipment. We see the benefit of where the nitrogen was left behind and where those cows were winter managed,” Lardner said.
In this study, both straw and hay bales were provided to the cows in an attempt to reduce feed costs. But, the researchers found that the cows consumed mostly hay and used straw for bedding.
“In our particular instance, the leftover straw or feed acted as litter, which is very good for conserving moisture and nutrients. We saw it capturing limited rainfall that happened the following summer, and we saw increased forage yield and pasture response because of that litter that was left out there,” he noted.
Summarizing results from the study, Lardner stated that winter grazing systems had no effect on cow condition or cow performance.
“However, looking at the soil nutrient profile, winter grazing increased soil nitrogen levels roughly two to three times greater on bale process or bale graze sites, compared to the control sites,” he remarked.
Pasture yield also increased 2.3 to 2.9 times in the feed sites relative to the control pasture.
“Finally, producers should choose their winter feeding sites adequately to not only increase nutrient efficiency but also to reduce environmental impact,” he concluded.