Brian Reidy: Planning ahead to avoid grass tetany at spring turnout
At turnout, the most important thing to monitor is grass intake and rumen fill, writes ruminant nutritionist Brian Reidy.
I plan to get cows and calves out at home over the coming weekend. The farm was blanket spread with 30 units of nitrogen last week and all of the fencing has been updated.
Even with plenty of feed in front of them, my cows have been asking me to open up the shed door and let them out over the last week as they look out at the nice weather.
The last few days have been fantastic and ground conditions have improved hugely. Growth is still slow at the same time as it has remained cold.
Rehousing can be very stressful for both the farmer and the cattle, as it will often mean grouping stock again for several pens or sheds.
It is not easy to put sucklers out to grab grazing opportunities as sorting groups when they return indoors can be a big job. It is a critical time in their production cycle as increasing grass intake quickly for both cow and calf will improve performance and reduce stress and production costs.
At turnout, the most important thing to monitor is grass intake and rumen fill. Poor intakes of grass should be supplemented with forages or concentrates. Now that you have calved the cow your attention must shift to getting her back in calf again.
Suckler cows will generally lose some body condition after calving, but this needs to be controlled in order to produce enough quality milk for the calf, while also helping her to come back in heat and ultimately go back in calf.
Grass quality and supply will determine if you need to supplement cows with additional forage or concentrates. If you need to supplement suckler cows on grass, then it may be easier to keep them in until there is sufficient grass before turning them out.
It is a lot of work and could cause damage in paddocks to attempt supplementing sucklers outdoors. I certainly won't be letting the herd out at home until I am pretty sure that they can stay out long term.
It's very common every spring to hear about suckler cows going down with tetany. Grass is deficient in magnesium, and it is worth noting that cows are generally deficient in magnesium well before they go down with tetany.
A magnesium deficiency may result in poor saliva production and subsequently in poorer digestion of feed and lower production levels. Magnesium is a major macro mineral essential for performance in cattle.
There are many ways to supply sufficient magnesium to cows. Some more effective than others:
- High-mag lick buckets.
This is probably the most common method of magnesium feeding to suckler cows and works very well once buckets are always accessible. Some will use a High-mag feed block to supplement grass and prevent tetany.
- Magnesium in water troughs.
A popular method, in wet weather, where cows drink less from troughs, it may not be as effective.
- Meal feeding.
Some may feed a dairy nut or ration to sucklers during times of tetany risk, particularly if grass is in short supply.
- Dusting paddocks with magnesium.
A little bit hit-and-miss and not as reliable as I would like.
- Supplying a forage such as silage or straw will also help to prevent tetany as it slows down grass passing through cows, allowing for better extraction of nutrients.
Please make sure that you are using the most effective supplementation for your herd before you depend on any single method of tetany protection.
Whichever method you choose, be sure to stick with it and deliver it accurately and consistently.
Some may consider turning out dry cows before calving. This can be a risky strategy as it is difficult to control cow condition at grass.
It is also a risk with regard to milk fever and held cleanings in older cows due to high potassium grass.
It really is a better idea to keep cows housed until calved. Cows calving down without complications will be easier to get back in calf.
At the very least cows should return indoors by night, as this will help to control condition and make it easier to assist calvings where necessary. Cows in the habit of going in and out will also be easier to bring in if they need help.
