▪ Feeding a partial total mixed ration (TMR) to grazing dairy cows looks more profitable than supplementing pasture forages with just grain.
That's according to researchers at the USDA-ARS Pasture Systems and Watershed Management Research Unit, University Park, PA. Using Dairy Forage System Model (DAFOSYM) computer simulation, they compared the environmental and economic impact of three feeding strategies on a 250-acre dairy farm in central Pennsylvania. The 100-cow herd was either grazed and fed a grain supplement, grazed and fed a partial TMR, or housed in confinement and fed stored forages year-round.
Milk production was set at 16,500, 20,000 and 22,000 lbs/cow, respectively, for the three systems. The confinement system was most profitable, the pasture plus grain supplement strategy was least profitable, with pasture plus TMR being intermediate.
While the pasture plus TMR looks slightly less profitable than confinement feeding, net return likely would show less year-to-year variation, say the researchers.
The pasture plus grain supplement farm produced the most hay and silage, and had the highest forage sales. In part because of that, its nitrogen leaching losses were lowest.
▪ Good-quality tall fescue silage can replace all or part of the alfalfa in dairy cow rations. But you'll need to feed more grain to get the same milk production.
Cornell University researchers reached that conclusion after feeding alfalfa, fescue and various alfalfa-fescue mixtures to early lactation Holsteins.
In each case, silage was fed to provide 1.1% of body weight as NDF. The silage was 100% alfalfa; 67% alfalfa-33% fescue; 67% fescue-33% alfalfa; or 100% fescue. All of the rations were balanced to meet NRC requirements for total protein, energy and minerals.
Milk production went up as the amount of fescue in the diet increased. That was due to higher dry matter intakes, say the researchers. Fescue is higher in NDF than alfalfa, so high-fescue rations contained less forage and more grain, they explain.
▪ Shredding instead of chopping corn silage would increase its effective fiber and reduce sorting in the feedbunk.
That's according to Penn State University researchers, who modified a chopper by first removing everything but the feeder rolls. Then they mounted four shredding rolls, operating at different speeds, after the feeder rolls, followed by a flail blower/cutter mechanism.
The corn was shredded longitudinally, resulting in many long, thread-like fibers.
Corn that was 65% moisture at harvest was stored in a bag and then fed to Holstein heifers. Those heifers ate slightly less silage than others fed chopped corn silage. But they consumed 2.5 times more long fibers (greater than 0.71”).
Mixing prior to feeding reduces forage particle size. Yet with the shredded silage, 30% of the mass remained longer than 0.71”, even after 30 minutes of mixing in a four-auger TMR mixer.
The researchers concluded that, with different harvesting methods, corn silage could be an important source of effective fiber in addition to energy in dairy rations.
▪ University of Delaware researchers found that increasing the cutting height of silage corn from 5" to just under 18" improved its nutritive value. But silage yield was reduced by about 10%.
Three leafy silage hybrids (TMF 199, 108 and 2404) were cut at both stubble heights at black layer and half milk-line stages. The higher-cut silage was higher in dry matter and starch than the lower-cut corn, but crude protein and ADF were lower. NDF and lactic acid also tended to be lower.
When fed to dairy cows, the higher-cut silage showed tendencies for greater NDF digestion, higher milk production and improved feed efficiency, say the researchers.