Rearing spring-calved heifers to calve at around two years of age from grazed grass can be a challenge. Setting clear liveweight targets over the rearing period will help to ensure maturity is reached in time to serve the animals and get them in good enough condition to calve down, says Tom Goatman, DairyCo extension officer.

For the greatest economic value heifers need to be grown to an adequate size for successful bulling at 15 months of age to calve down at about two years old, essential in a block calving herd and very desirable in those herds with a greater spread of calvings.

Feeding calves at grass

Heifer calves should be given at least two litres of colostrum at birth and reared on a regular system to about 4-6 weeks of age. The calves can then be turned out into a sheltered field and fed cold milk once a day from a 'milk bar' (approx 4.5 litres/head/day) with good hay always on offer. Young calves settle more rapidly to this system and do not wander far away.

They should always be offered the best grass and moved-on daily, ideally being kept about a week ahead of the cows in the grazing rotation and well separated from them to avoid disturbance. When the calves reach about 90kg liveweight (at around three months of age) they should be weaned on to grass-only diets.

Concentrate feeding should be unnecessary but check weights frequently to ensure growth rates are being sustained, perhaps using weigh bands.

To give them top quality grass sufficient to sustain the required growth rates, calves should be rotationally grazed ahead of the cows until mid-summer. At this stage they should be well-grown and can stand slightly tougher grazing conditions.

From August of their first summer the calves can be block-grazed and moved less frequently.

They will not suffer from having a slightly slower growth rate at this stage of their lives.

Providing they are meeting their target growth rates youngstock can safely be kept outside over their first winter on block grazing or forage crops. They do, however, need to be offered adequate dry matter and may need to be moved regularly to ensure they do not poach fields badly. Some hay or big bale silage may need to be offered and clean water must be freely available.

  • Youngstock should be weighed regularly to ensure target growth rates are being achieved.
  • During the second year of their lives, heifers can be block-grazed, utilising outlying or difficult-to-access fields.They can also be used as a grass management tool to clean up grass left in paddocks when the cows are moved on. This helps to reduce the labour and can keep them settled.
  • Yearlings have large appetites and are capable of achieving good dry matter intakes.Providing they are not under-fed for long, compensatory growth will be achieved when they are moved to fresh grazing.
  • While pastures used for young calves need to be of very high quality, grass provided to yearlings can usefully be allowed to become slightly more mature with a slightly higher fibre content to aid growth of frame and development of gut capacity.

To help with management, field and track fences can usefully have an additional electric wire at a lower level to prevent calves from escaping. It is important to ensure calves can reach into water troughs and are not at risk of falling in.

With small calves it may pay to place a temporary trough of smaller dimensions in their fields and move it with them. Some field shelter may also be required for smaller calves. If there are no good hedges or convenient buildings available, shelters can be constructed from big bales covered with sheeting.

Grass+ Factsheet 14, Rearing heifers at grass is available to download from

Health of youngstock at grass

Parasites and other disease problems can be an issue for young calves, seriously compromising performance.  Calves should always be given access to clean paddocks by grazing them ahead of other stock and a careful watch should be kept for coccidiosis.  In addition the following guidelines should be considered in relation to the control of worms sustainably.

  • Work out a control strategy with your veterinarian.
  • Use effective quarantine strategies to prevent the importation of resistant worms in newly purchased cattle.
  • Test for anthelmintic efficacy on your farm.
  • Administer anthelmintics effectively ensuring the correct dose and manufactures guidelines are followed.
  • Use anthelmintics only when necessary.
  • Select the appropriate anthelmintic for the task.
  • Adopt strategies to preserve susceptible worms on the farm with the aim of reducing heavy selection of anthelmintic resistance.
  • Reduce dependence on anthelmintics through alternative control methods such as grazing management.

"We calve in February, and in a usual year the calves are weaned and go out to graze in April," says Dave Lee who milks 320 spring calving cows near Welshpool in Powys.

"We then make sure that get access to plenty of good quality grass. We basically provide it ad-lib for the first three to four months of grazing and move them frequently to make sure they get the best quality. After that we graze them a little harder as they've got the idea of what to do by then.

"The kind of animal we've got is also relevant. Crossbred heifers don't need to reach the weight of some other breeds before breeding and they rear well on grass.

"We worm all calves after six weeks and eight weeks at grass and really need to be observant and get in their quick and treat as soon as you see any signs of coughing," Dave Lee concludes.

The Control of Worms factsheet can be downloaded from