Hitting heifer rearing targets at grass

Rearing dairy heifers to reach specific weight targets is a critical part of reducing replacement costs and enhancing profit on Dairylink Ireland farms.

Programme participants are asked to weigh their heifers at various stages during the rearing period. The main targets are 360-400kg liveweight at 14 to 15 months old for first service and calving down at two years of age with weights approaching 600kg.

To reach these milestones, it is important that the animals achieve a minimum growth rate of 0.80kg/calf/day during the grazing season.

The performance of heifers on phase two Dairylink farms was recently reviewed by Joe Patton from Teagasc and various action points were identified to help farmers achieve this target growth rate.

Firstly, programme farmers need to keep weighing heifers at regular intervals to assess progress and make appropriate management decisions.

Joe points out that while averages may give an indication of overall performance, it is critical that the poor performers are identified within each and action is taken to help to get these individual animals back on track.

The sooner this happens during the grazing season, the better chance there is of rectifying the problem.

Joe highlighted that if calves are exceeding target LWG, there may be the opportunity to reduce the use of concentrate inputs and make financial savings

The benefits of this approach was seen on Dairylink farms last year. When Stephen Wallace weighed his heifer calves in May 2020, it was found that around 25% of animals had a liveweight gain (LWG) below 0.65kg/calf/day. These animals were subsequently placed in another group and offered 3kg of concentrate instead of 1.5kg. This allowed them to achieve a LWG of 1.0kg/calf/day and meant they were able to catch up with the remaining calves on the farm and reach service weights on time.

By contrast, Joe highlighted that if calves are exceeding target LWG, there may be the opportunity to reduce the use of concentrate inputs and make financial savings.

However, such decisions can only be taken if the liveweight data exists in the first place.

Grass

Aside from concentrates, heifer replacements must have access to good-quality grass to achieve target LWG. A total pre-grazing cover of around 2,500kg DM/ha was recommended by Joe.

The risk of damage by internal parasites can be reduced by grazing calves on low-risk pasture

Farmers should set up a heifer grazing system that allows for areas to be removed for silage, if required, to maintain grass quality. It is also important that calves can be moved around the grazing platform easily to maintain grass quality and LWG.

The risk of damage by internal parasites can be reduced by grazing calves on low-risk pasture, such as newly-sown leys, silage aftermaths, or grass that had been grazed by cows or sheep. Permanent pasture or land grazed by young stock in the previous year poses a higher risk to heifer calves.

In recent years, Joe has encountered some situations where late autumn-born or spring-born calves have had scour-like symptoms and reduced LWG around two or three weeks after turnout.

He suggested this is due to a dietary issue and recommended that any farmers who have encountered this problem previously should take steps to ease the transition to grass. This includes ensuring that calves are eating at least 1kg concentrate per day by weaning.

It may be useful to turn these animals on to bare paddocks and offer some straw and concentrate for the first few days before being moved on to the more lush, leafy pasture.

Another piece of heifer rearing advice is to vaccinate youngstock against clostridial diseases, such as Blackleg, to reduce the risk posed by these infections.

There are 140 cows grazing full-time on Stephen and Hazel Wallace’s farm and herd performance is being maintained at around 29.5l/cow/day.

Heifer calves had also been turned out and weighed recently.

Analysis of the results showed that all calves were performing well and reached a LWG of 0.83kg/calf/day by six months of age.

Calves are currently grazing grass with an average total cover around 2,000-2,500kg DM/ha and are receiving 1.5-2.0kg/calf/day of a maize gluten concentrate mix.

Stephen is happy that yields of grass were significantly higher than what was harvested at the same time last year

Stephen is also planning to harvest his first-cut silage this week. Grass for first-cut silage had previously received 120kg N/ha (96 units/ac) through the application of 30m3/ha (2,700 gallons/ac) slurry in February, plus 1.5 bags protected urea/ac split over two applications in March.

Stephen is happy that yields of grass were significantly higher than what was harvested at the same time last year.

In addition, when a selection of field samples were assessed for levels of soluble carbohydrate using a refractometer, it was found that the samples collected had a concentration of around 4-5%.

There should therefore be enough soluble carbohydrate available to ensure that a successful fermentation occurs.

The plan is to allow grass to be mowed and wilted for 24 hours to achieve a target dry matter of around 25%.