Grazing: The forecast for the weekend and into next week is for a return to wet conditions. While last week wasn’t ideal for grass growth, it was a great opportunity to get freshly-calved cows out to grass. Keeping them out will be the challenge considering the forecast. On/off grazing, where cows are grazing for two or three hour periods in the day, will help prevent damage, as when cows are grazing they will not be walking around aimlessly causing damage. They need to be tuned into this, meaning they can’t be going out full of silage. Ideally, cows shouldn’t have access to silage for four or five hours prior to going out.
The other thing is you really have to pick your moments for grazing. If it’s raining, then they can’t go out. Maybe hold them in the yard for an hour or so if you suspect the day is going to dry up. The best grassland farmers will spend a bit of time finding the right paddock (dry, good access points) and the right moment to let cows out. Failing that, cows will have to be kept in until conditions allow and that will be the reality on many farms next week. Feed the best quality silage available to the milking cows. See Grass+ page 38.
Milk fever: Milk fever seems to be an issue on many farms this spring. The general trend is that older cows in too good body condition are going down with it. Vets say that a downer cow is just a clinical case and there are likely to be subclinical cases in the herd that won’t be noticed but could be causing problems, such as retained cleaning, mastitis, etc.
The main cause of milk fever is cows being unable to mobilise enough calcium after calving. There are a number of predisposing factors, such as not enough magnesium before calving or high levels of potash in the silage. Having too much calcium in the diet pre-calving can also make them lazy at mobilising calcium after calving.
You can’t change the body condition score or the potash level in the silage now, but you can change their magnesium intake pre-calving. Spreading sweetened cal-mag or magnesium flakes on the silage of the dry cows, in addition to their ordinary dry cow mineral, will greatly increase their magnesium intakes. Spreading 60g per cow per day of sweetened cal mag (33% magnesium) will supply an extra 20g of magnesium. Magnesium flakes are generally lower in magnesium at 12%, so to get 20g of magnesium, you need to feed 170g of flakes on the silage or in the water. Flakes tend to be less palatable than sweetened cal mag. Other options include giving a calcium bolus, a high calcium liquid feed or a bottle of calcium under the skin to freshly-calved cows.
Storing milk: At this time of year, freshly-calved cows not yet supplying milk to the bulk tank are producing more milk than the calves can consume. Storing this milk and feeding it back later will mean more milk sales or less milk replacer used. Milk can be treated with an acid-based preservative that will keep it fresh for a month or so. Milk can also be turned into yogurt, but this is less effective with milk from fresh cows that got antibiotics at drying off.