Heifers should ideally calve down between 22 and 24 months.
“Heifer rearing on a dairy farm is often seen as a high-cost enterprise with little return,” says Alan Hopps, Senior Dairying Development Adviser with the College of Agriculture, Food and Rural Enterprise (CAFRE).
However, Alan emphasises: “If heifer rearing is prioritised, heifers can calve at a younger age, produce more milk in their first lactation, and remain productive on the farm for longer. This not only reduces the need for land due to fewer heifers present on the farm, but it also lowers the carbon footprint and enhances overall farm profitability.”
Alan outlines several measures of successful heifer rearing.
Calving Age
Heifers should calve at 22-24 months. Calving too early can lead to ‘calving pattern creep’ causing heifers to calve outside the herd’s calving window if not managed properly. For all-year-round calving herds, calving at 21 or 22 months is not an issue if heifers are well grown.
Retention Rate
Aim for 90% of heifers to calve again in the herd for a second lactation. Heifers leaving the farm during their first lactation won't cover their rearing costs.
Milk yield
Heifer yield should exceed 80% of mature cow yield. For instance, if the herd averages 8,500 litres, heifers should produce over 6,800 litres, maintaining an average herd yield of 8,000 litres overall.
Weight at Service: Heifers should reach 55% of their mature weight by service. For a herd averaging 650kg, heifers should weigh around 360kg at breeding, which can start at 13 months if they meet the target weight.
Weight at Calving
Heifers should calve in at 85% of their mature weight. Thus, for a herd of 650kg, heifers should weigh at least 550kg at calving.
Alan Hopps, CAFRE Senior Dairying Adviser.
Alan also highlights crucial factors for a successful heifer rearing enterprise.
Starting with careful sire selection. Always choose sires with a higher potential transmitting ability (PTA) for milk than the herd's average to ensure progress in improving the milk yield potential of the herd.
Remember, a herd with a PTA of zero on average still has the potential for a herd yield of 9,000 litres. Other elements of a bull’s figures which are important to consider are PLI, lifespan, fertility index and components. Functional type should also be considered to help ensure a longer herd life.
The rearing phase is very important. The first meal a heifer calf gets, 4 litres of colostrum, is the most important of its lifetime and vital for its future. Following this, a milk feeding regime should ensure optimal growth, with peak calf milk replacer feed rates exceeding 1kg per calf per day or 8 litres of whole milk.
Ensure heifer calves are reared in hygienic, well-ventilated housing to promote growth.
Reducing diseases such as scours and pneumonia during the rearing period is essential. Work with your vet to create a vaccination program and ensure hygienic, airy housing to promote growth.
Aim for an average growth rate of 0.8kg/day from birth to calving, maintaining consistent growth throughout the heifer's life if possible.
“If you don’t measure something, you can’t manage it,” suggests Alan. “An interactive program on the on-line services section of the DAERA website, under the BOVIS heading, allows you to track heifer performance against your targets.
“You can enter weights against individual heifers that automatically populate from NIFAIS. Weights can be from a heifer weigh band measurement or an actual weighing. A graph of heifer weights against their target is automatically produced. If heifers lag behind target, nutritional adjustments can be made to help them catch up.”
Alan concludes:
“Some of the best heifer-rearing farms in County Armagh are achieving average first-lactation milk yields of 10,000 litres, with an average lifetime yield of 45,000 litres. These heifers have a weight at calving of 650kg and a conception rate in their first lactation of 54%.
“While not all farms will target such high yields, this demonstrates the potential achievable with excellent genetics and careful management of your heifer enterprise.”