Normally, the focus is on the pre-calving nutrition of spring-calving cows but it has to be remembered that there are lots of herds calving late summer or early autumn (and some at other times too!).

The same principles of pre-calving nutrition apply no matter what time of year calving occurs. As always, cows that have a tight calving period are easier managed – it is virtually impossible when things slip further than 12 weeks to meet the nutritional needs of all cows in the herd at one time.

Cow condition

Late summer and autumn calvers are traditionally trickier to manage with them being at grass when it is often harder to control body condition.

Now, at turnout, is a good time to check condition of the cows and if cows are fatter than you would like to see, take steps now to reduce condition. This may be putting cows (once weaned) on rougher grazing or keeping the calves on cows longer to reduce condition through producing milk. However, this can be counterproductive as cows will need to be on better grass for the calves (as more than 75% of their nutrition at this stage will come from grazing) and therefore may not actually lose weight!

If cows and calves are on poorer grazing, calf growth rates will suffer if there is insufficient grazing which needs to be considered. For cows calving later in the summer/autumn, keeping calves on cows longer can help reduce the risk of summer mastitis that comes with weaning in the summer months. Calves do need to be weaned at least one month before the calving start date to allow for colostrum production for the next calf.

If there are known later calvers (identified through pregnancy scanning) graze them on some poorer ground – they are further off calving and have lower nutritional requirements. Save the better ground for more priority stock, such as the weaned calves.

An alternative to this would be to increase stocking density to limit grass intake if no rougher grazing is available. Low quality baled forage could also be provided if grass becomes too scarce. If grass is bare and straw is fed in ring feeders pre-calving, they will need to be supplemented with additional protein/energy if they are eating more than 5kg of straw/day, as they will not be consuming enough grass to meet their requirements.

In late summer/autumn-calving situations, cows can be fatter and are lazier and because of this eat less in later stages of pregnancy and therefore have lower mineral intakes. Monitor condition throughout the year and try not to allow big swings in body condition by taking control of rationing and managing grazing pressure as much as possible.

Cow nutrition is relatively easy to amend if addressed early enough but discovering cows are too fat one month before calving is too late to alter the diet. Weight change needs to happen gradually and not by extreme rationing which can do more harm than good by causing metabolic stress in cows.

Mineral supplementation

Grass is mainly low in trace elements, boluses are a good way of ensuring trace element deficiencies in grass are corrected, however most boluses do not contain macrominerals (like calcium and magnesium) and vitamins so external supplements such as buckets and free-access minerals will address these shortages.

Energy, protein and mineral status can all be checked around one month pre-calving by metabolic blood profiling through your vet which involves blood testing 5-6 animals. This will allow any nutritional deficiencies to be corrected ahead of time.

Cows calving on lush grass especially after a dry spell, then rain when the grass bolts, are at risk of being low in magnesium. This perhaps doesn’t present as grass staggers, but it can contribute to 'Slow Calving Syndrome' where cows lack magnesium to mobilise their own calcium reserves required for uterine contractions and they start calving but struggle to proceed. This can cause calves to lack oxygen, have a poor suckle reflex and colostrum intake with the prolonged calving.

Although rare in beef cows, there is also the risk of milk fever. This is magnified by the fact that mineral supply to cows at grass relies on cows helping themselves to free access powder or buckets. Grass that is high in potash can reduce magnesium availability in the gut so avoid calving in fields that have had a lot of slurry application or high K fertiliser. Correcting the magnesium deficiency at grass can usually be easily sorted, speak to a nutritionist for advice if you encounter this problem.

Make sure that your mineral supplement is high in magnesium when cows are calving at grass. If you have administered a trace element bolus pre-turnout, then trace elements are less important in your external bucket or powder supplement and a suckler cow high mag mineral should suffice.

Off the shelf pre-calving mineral supplements can often only contain 10% magnesium compared to around 20% or more in Hi Mag supplements. Cows need at least 25g of magnesium a day, 30-40g if potassium is high in the grass. Around half of their magnesium intake will come from the grass (around 10-15g)

Taking time to plan nutrition pre-turnout for cows calving summer/autumn is well worth it to help minimise potential problems over the calving period.