Poor conception rates in replacement heifers are often due to heifers being underweight by the start of the breeding season.
The task of achieving this target pre-breeding weight begins once a replacement heifer is born, until mating start date (MSD) when she reaches approximately 13 to 15 months-of-age.
As the future replacement heifers approach the stage of weaning, we must ensure that an adequate weaning plan is in place – to minimise any stress placed on the calves – as they make the switch from whole milk or milk replacer to solid feed.
Poor management of calves pre and post-weaning can result in poor potential growth rates, health issues and failure to reach heifer rearing weight targets.
- Calves should not be weaned until they are continually eating 1kg of concentrates per day;
- Weigh regularly to monitor weights: Holstein-Friesian calves should be at least 100kg at weaning and Jersey-cross calves should be at least 80-85kg at weaning;
- Underweight calves should be grouped together and continue being fed milk or milk replacer until target weights are achieved;
- When weaning, the volume of milk should be decreased gradually over the course of a few days.
Post-weaning management:
- Calves should be grazed in a leader-follower system of grazing – ahead of older cows;
- They should be moved regularly to ensure they have continuous access to fresh grass;
- Concentrates should continue to be fed (1-2kg/calf) until grass intakes increase.
Furthermore, once the calves are weaned and at grass, it is important that a consistent worming programme is put in place.