Managing nutrition for cows after turn out

Spring is proving challenging for spring calving and lambing so far with the long-range weather forecast looking tricky. Keeping cows and calves at foot inside for longer periods brings challenges with hygiene and disease build up which will need to be very carefully managed. Added to that straw is scarce and expensive. Turn out of strong calves with good mothers helps and is necessary.

Below is an article written by our SAC Consulting specialist beef team on managing nutrition for cows after turn out, especially relevant given the more challenging spring weather conditions.

For freshly calved suckler cows recently turned out to grass it is important to ensure there is enough grass cover to meet cows’ nutritional requirements and if there is not, they must be supplemented if they are to milk well, keep condition and be fit for the bull.

In well managed grazing systems, and some early grass growing areas, this may not be an issue. However many areas grass growth is later due to the climate, grass quality, soil nutrition or too many mouths on it during the winter months. In these situations, where grass is lacking, cows prioritise milk, they lose weight themselves and their return to oestrus is delayed.

How to decide if supplementation is required:

• A lactating suckler cow needs approximately 135MJ of energy per day which is around 60kg of good quality grass (20% DM) which is around 12kg of dry matter. If grass is below 6cm then she is likely to need supplemented. Also grazing grass very short will only delay its regrowth.
• Using a sward stick or ruler to measure a representative area across the field. In a set stocked system spring grass should be at least 6cm (around 2000kgDM/Ha). If fields are bare (even if the weather is good) it may be the best option to keep cattle in a bit longer and allow re-growth and prevent damage to the grass that comes from supplementing forage outside.
• Think about how many cattle there are per hectare (daily demand) and what the growth of the grass is likely to be each day (daily supply) to ensure cattle are getting what they need. For example, grass in April growing could be growing at 10-16kg/Ha/day and by May it could be up to 60-70kg/Ha/day. So, in April 1Ha would meet the needs of 1 cow, in May it meets the needs of 6 cows. Check www.grasscheckgb.co.uk to estimate the grass growth in your area for the time of year.

Turnout checks:

• Grass height –check for a minimum of 6cm in the spring for set stocking. Manage stocking rates according to the growth of the grass.
• Rumen fill - the triangle area between spine, hip and rib cage on the lefthand side of the cow gives a good indication of rumen fill, if this area is sunken and an obvious triangle then the cows are not eating enough, check middle of the day after grazing, first thing in the morning it will be emptier.
• Coat changes - Are they looking sleek and losing winter hair – indication of thriving.
• Grazing behaviour – look for cows grazing well for long periods and chewing the cud while resting. A sign of insufficient grass intake would be cows standing not grazing and not cudding for long periods.
• Weather - If weather turns bad for a prolonged period, time grazing will be replaced with time sheltering and supplementation with additional forage or concentrates to keep energy intake up and staggers risk low is an important consideration.
• Magnesium - low magnesium risk (staggers) is highest in newly calved cows at grass. Bare fields or very fast growing, lush grass means low magnesium intakes for cows. Stress and weather also play a role here too. Mitigate the risk by providing a magnesium supplement either via free access high mag minerals or buckets or the safest method by providing a high magnesium mineral in a barley carrier or proprietary roll which ensures each cow gets her daily allowance. If the risk is high for staggers, the cost of these mitigation measures is a small price to pay.

Well managed grass is the key to success, however good weather will tempt turnout even when grass growth is not ideal. The message is simple – if in doubt feed them – it may cost you more in the short term, but it will cost you more if you don’t in the long term.

Posted by SRUC Veterinary Services on 15/04/2024