An LIC study of more than 105,000 animals showed 73% of them were more than 5% below liveweight target based on their breeding value for liveweight (503kg +/- liveweight BV) at 22 months old.
When did you last check your heifers? What are their liveweights? The table displays the live weights at different ages based on breeding value liveweight. How do your animals compare?
Heifers normally reach puberty at half of their mature liveweight and research has found that heifers at 60% of their mature liveweight at the planned start of mating is optimum.
Research also shows a strong correlation between liveweights and puberty. Ultimately, the faster an animal grows the sooner it reaches puberty, cycles and gets in-calf, aiding the six-week in-calf rate. This means, in the remaining seven months before the animal enters the herd and calves, a heifer needs to grow a further 30% of its mature liveweight.
Potential issues from October to May which might prevent heifers reaching liveweight targets before entering the herd include:
- a dry summer causing poor quality or quantity of feed or both
- competing with other enterprises for the best quality feed eg beef price is high
- poor growth over the previous winter meaning the animal is already behind
- pasture being stored for winter grazing cows.
DairyNZ, in conjunction with Beef + Lamb New Zealand, is leading heifer grazing focus farms to improve the way heifers are managed and increase the likelihood of heifers reaching target liveweights and fulfilling their potential for milk production and reproduction.
The project will include three or four field days a year for the next two to three years, timed to target regional issues and provide a forum for discussion between dairy farmers and heifer graziers.
The structure will provide a forum to gain new ideas and exchange information, and will allow farmers to be actively involved in the development of knowledge and resources to help the industry improve its heifer rearing practices.
The project is currently being run in Canterbury, Manawatu, South Waikato and Northland. To check when the next field day is in your area, check the events page at www.dairynz.co.nz/events or contact your local consulting officer.
Scott Cameron is DairyNZ consulting officer for Horowhenua-Wanganui-South Taranaki
