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 is £738 per heifer (Dairy benchmarking 2004/05). The aim of any heifer rearing program should be to cost effectively produce well developed heifers, capable of expressing their full genetic potential. The targets set for rearing spring-born high genetic heifers at Greenmount Campus are to calve them at 2 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.
The management policy adopted during the rearing period has a major impact on costs incurred and on subsequent heifer performance when they enter the milking herd. In conjunction with AFBI Hillsborough and John Thompson & Sons, CAFRE staff are seeking to ensure dairy farmers rear and manage dairy heifers to achieve their genetic potential.
Grazing Management
Effective grassland management is vital to the successful rearing of spring born replacement heifers. Improvements in grazing management will result in reductions in concentrate inputs and rearing costs. Nevertheless, maintaining animal performance at grass can pose serious 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 either calving down at over two years of age, or too small to suit the system. It is therefore vital that consideration is given to setting up an effective grazing system for these heifers.
Spring born calves at Greenmount Campus 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 compound. Parasites are controlled using a pour on anthelmintic programme, which is given at 5 and 13 weeks post turnout. These calves are normally housed in early to mid October.
Second grazing season
These heifers should be in-calf so concentrates can be reduced approaching turnout resulting in no supplementation at grass. Target growth rates at this stage are 0.80 - 0.85 KG per animal 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.
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.
Summer mastitis can also be a problem among in-calf heifers during summer/early autumn and often leads to the loss of the affected quarter.
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 fortnightly 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:
- Calve heifer replacements at 2 years of age;
- Ensure that animals achieve target weights at the appropriate age;
- Maintain animal performance at grass by adopting good grazing management.
Any farmer interested in Benchmarking their dairy heifer enterprise should contact their local Dairy Development Adviser.