Bloat is the death you find, not the one you watch. A cow that looked fine at daylight is dead by mid-morning, laid over on her left side with her rumen ballooned up behind the ribs. Nothing else on summer grass moves that fast. If you’re grazing regrowth alfalfa, an old crested wheat field that’s gone to clover, or turning pairs onto an irrigated meadow heavy with legumes, June and early July are when it bites.
The problem is froth. When cattle eat a lot of lush, immature legume in a hurry, the rumen fills with a stable foam that traps the gas they’d normally belch. The gas can’t come up, pressure builds, and the swollen rumen presses on the lungs and the big vessels. They suffocate. It isn’t the plant being poisonous. It’s a healthy cow eating too much of something too rich, too fast, on an empty stomach.
Know which pastures set you up
Alfalfa is the usual culprit, especially fresh regrowth after a cutting or when it’s vegetative and wet. White clover and alsike in an old flood-irrigated meadow will do it too. Grass pastures don’t cause frothy bloat, and a stand that’s a solid mix of grass and legume is a lot safer than a pure alfalfa field. The danger climbs when the plants are young and lush, and it climbs again after a light frost or a heavy dew, when the plant cells are turgid and break down fast in the rumen.
The riskiest move most people make is turning hungry cattle onto that kind of feed. A cow that walks onto lush alfalfa on an empty gut will gorge. The same cow, full of dry grass or hay, picks at it and does fine.
Turn them out full, not hungry
Feed them before you move them. Fill cattle on grass hay or on a rougher, grassier pasture so they aren’t starved when they hit the legume. Make the switch in the afternoon rather than first thing in the morning, after the dew is off and the plants have dried down some. Wet forage from dew or rain is worse than the same field dry.
Don’t turn out right after a cutting and don’t turn out onto a field that’s just been frosted until it’s had a few days. And when you do put them on new legume ground, don’t leave and go to town. The first two or three days are when bloat shows up. Ride through them morning and evening and count.
A few practical tools help:
- Poloxalene bloat blocks or feeding it in the mineral ahead of and during the risk period. It breaks up the foam. The catch is cattle have to actually eat it, and shy eaters get none of it, so it’s a backstop, not a guarantee.
- Keep good dry grass hay available in or next to the legume pasture so they’ve got fiber to fall back on.
- Move cattle onto a new strip late in the day, not onto a fresh, dew-soaked block at dawn.
Some outfits graze pure alfalfa for years by managing it hard — full cattle, afternoon moves, bloat surfactant in the water or mineral, and never a hungry animal on wet regrowth. It can be done. It just doesn’t forgive a careless day.
When you find one blown up
Time is everything. A cow in early bloat is uncomfortable, standing off by herself, maybe stamping and slobbering, left side rounded out. Get her up and walking — moving her sometimes helps her belch. If she’s still standing and it’s mild, a bloat drench with a surfactant, poured in and worked around, can break the foam.
If she’s down, breathing open-mouthed, and swelling fast, you’re out of time for gentle measures. Passing a stomach tube can relieve gas bloat, but frothy bloat is foam, not free gas, so the tube may not fix it alone unless you get surfactant down through it. In a true emergency with a cow that’s going to die in minutes anyway, a trocar or a clean knife stab into the high point of the left flank, into the rumen, will let the pressure off. It’s a mess and it invites infection, but a live cow with a hole in her side beats a dead one. If you’re not sure where or how, that’s a call to your vet before you need it, not after.
The honest truth is that saving a badly bloated cow is a coin flip. The whole game is keeping them from getting there — full guts, afternoon turnout, dry forage, and eyes on them the first few days on any lush legume stand. Do that and alfalfa regrowth is some of the cheapest gain you’ll put on cattle all summer. Skip it and it’ll cost you your best cow on a Tuesday morning.
