Winter feeding replacement heifer calves

Calving replacement dairy heifers at 24 months of age is a necessity in order to obtain maximum lifetime productivity & long-term profitability in the milking herd.

Therefore, replacement heifers must reach 60% of their mature weight at breeding next spring. This means that replacement heifers need to achieve a steady gain of approximately 0.70-0.80 kg/day from birth. Interruptions to performance during the lifetime of the heifer may offset target weights being achieved. Recent Irish data suggests that increasing average daily gain (ADG) in the pre-breeding period up to about 800g/day is beneficial to first lactation milk yield.

Ideally heifers should have been weighed in August and smaller calves given preferential treatment (e.g. higher quality grass, concentrate etc.) throughout the summer months of their first grazing season. Heifers should be weighed again entering housing period. At housing separate heifers in groups relative to the target weight to feed according to their requirements needed to achieve the target weight at breeding. The target at housing is 40% of mature body weight and 50% in February when turned out to grass. Over the first winter period, the ADG tends to be lower around 0.5 kg per day, however this can be compensated by greater gains of 1 kg per day in the spring on grass, resulting in the overall ADG of 0.7 kg over the pre-breeding period.

Farmers should feed good quality silage to weanlings to avoid growth checks and reduce the reliance on concentrate feeding. Therefore, it is important to analysis silage to determine the quality fed to stock on farm. Heifers on target (grass silage quality of ~ 70% DMD), would require supplementation of 0.5 – 1kg of concentrates while those behind target would need 2-3 kg of concentrate supplementation per day. Those above target will not need supplementation. As these animals are growing, they will need a high protein nut of 16%.

When concentrates are fed either on top of the silage or in a feed trough it is essential that all animals can eat at the same time. Additionally, it is vital that all animals have access to clean water at all times. For every kg of dry matter intake cattle will consume 5-7 L of water.

For any more information on this topic please contact your local Glanbia Ireland representative.

Hayes, C.J., McAloon, C.G., Kelly, E.T., Carty, C.I., Ryan, E.G., Mee, J.F. and O'Grady, L., 2021. The effect of dairy heifer pre-breeding growth rate on first lactation milk yield in spring-calving, pasture-based herds. Animal, 15(3), p.100169.

First Published: 22 October 2021