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MANAGING SPRING BORN REPLACEMENT HEIFERS AT GRASS

Kenny White, Dairying Development Adviser, CAFRE (Downpatrick)

Heifer replacements represent a significant investment in the future of any dairy enterprise.  The average cost of rearing a replacement heifer to enter the herd is £1220 (Dairy benchmarking 2007/08) and can be the single highest cost to the business after concentrates.  The aim of any heifer rearing program should be to cost effectively produce well developed heifers, capable of expressing their full genetic potential.
As part of a Heifer Rearing Project with AFBI (Hillsborough) and John Thompson & Sons, CAFRE Development Advisers and Technologists are encouraging dairy farmers to adopt management practices to rear heifers to calve into the herd at two-year old.  Spring born (Febearly April) calves are often cited as being more difficult to rear in terms of health, growth and development.  However many of these difficulties can be overcome by focusing on the main issues of disease prevention/control, and nutrition linked to grazing management.  The targets set for rearing spring-born high genetic heifers at Greenmount Campus are to calve them at two years of age at a pre-calving weight of around 570 KG.  The benefits of this are:
  • Savings in rearing costs.
  • Fewer replacements on the farm at any one time, thus less land and labour required.
  • Maintains a set calving pattern within the dairy herd.

Grazing Management

Effective grassland management is vital to the successful rearing of spring born replacement heifers.  Improvements in grazing management can result in reductions in concentrate inputs and rearing costs.  Nevertheless, maintaining animal performance at grass can pose major challenges to a heifer rearing programme in terms of:
  • Turn out date;
  • Minimising the stress often encountered immediately following turnout;
  • Maximising grass intakes by maintaining grass quality throughout the grazing season;
  • Effectively controlling parasites and flies.
Setbacks at turnout, particularly for spring born calves, can cause delays in reaching target weights resulting in animals too small to serve at 13 - 15 months of age, thus delaying calving age.  It is therefore vital that consideration is given to setting up an effective grazing system for these heifers.
Spring born calves at Greenmount are normally turned out from early - mid May.  In order to reduce the stress associated with turnout the calves are released into a sheltered area for a few days before being moved.  Calves at this stage of development are fed up to 2KG/calf/day of a 20 percent Crude Protein heifer-rearing ration.  Parasites are controlled using a pour on programme, which is given at five and 13 weeks post turnout.  These calves are then normally housed in early to mid October.

Second grazing season

At turnout for the second grazing season these heifers should be in-calf.  However they must continue to grow to ensure they achieve target pre-calving weight.  Target growth rates at this stage are 0.80 - 0.85 KG per animal per day.  On many farms this can only be achieved by feeding 2-3 KG of concentrates per day.
Popular grazing systems for youngstock include:
  • Leader-Follower grazing
  • Set stocking animals in early spring before moving them to silage aftermaths
A Leader-Follower grazing system is used at Greenmount Campus with the young calves forming the Leader group, with the in-calf heifers as Followers.  On many units heifers are grazed on the poorer grassland areas so it is important to monitor growth rates and alter concentrate feeding if needbe.  

Health care at grass

Animals grazing during their first season are prone to infection from internal parasites which include:
  • Ostertagiasis (roundworms)
  • Parasitic bronchitis (lungworm or husk)
Infection by these parasites can result in reduced performance or in more extreme cases death.  In-calf heifers at Greenmount are treated for parasites using a pour on programme which starts in late June and is repeated in late July and August.  Animals are also sprayed with fly repellent at two week intervals at this stage.

Summary

Replacement heifers represent the best genetics on the farm and are a significant investment in both capital and labour.  To maximise the return from your investment:
  • Aim to calve heifer replacements at two years of age;
  • Ensure that animals achieve target weights at the appropriate age;
  • Maintain animal performance at grass by adopting good grazing management.
heifers at grass