Keeping replacement weanling heifers on target this winter

Replacement weanling heifers are now coming into their first winter, and now that cows and young stock are coming in for the winter housing period, you need to know what to feed these heifers.

Prior to their first winter, heifers should be weighed to ensure they are on target to achieve the desired body weight at mating start date (MSD).

If they are not at the correct weight, supplementation should be added to their diet, as it will be too late to address the issue when it is time for breeding.

If you don’t have a scales, you can hire one from your local mart, as many farmers can get caught thinking that their heifers are on target, when they are not, as heifers need to be grouped and fed based on weight.

Replacement weanling heifers

The aim for the winter months is to ensure all heifers meet the planned pre-breeding targets, and to minimise live weight variation within the group.

The key target weights are that heifers are 30% of mature bodyweight at six-months-of-age and 60% of mature bodyweight at the start of breeding.

The target for your weanling heifers at housing 40% of their mature body weight, and the weight in kilos should be determined by their maintenance figure.

When these weanlings leave the shed in February, the target is for them to be 50% of their mature body weight.

Underweight heifers are considered to be animals that are 5% or more below their target bodyweight, which emphasises the importance of regular weighing of heifers to keep track on performance and to intervene if needs be.

The bodyweight targets for maiden heifers at breeding and for heifers pre-calving by breed/crossbreed, according to Teagasc are as follows:

These targets are not achieved without good husbandry, nutrition and constant monitoring and intervention, when certain heifers are beginning to slack.

All heifers should be treated for parasites before the housing period, as if these heifers are hampered by parasites, even if they have no clinical signs – it will be difficult for them to put on condition.

Feeding

In the scenario where lighter heifers are identified, they should be separated and given preferential care to get them back up to speed.

Heifers should be fed according to the quality of silage and live weight and if lighter heifers are eating silage of 67% dry matter digestibility (DMD), they will require 2kg of meal/day.

If silage is 72% DMD or above, the meal offered can be reduced to 1kg/day, and if heifers are target 1kg/day with 67%, DMD silage is sufficient.

It is all well and good offering this meal and silage to heifers, but it won’t be any good if the heifers don’t have enough feeding space, as a feeding space of 0.3m is required per heifer.

A weight gain of 0.3kg/day can be expected of a 72% DMD silage alone, while the introduction of 1.5 to 2kg of concentrates/day on top of this silage will see a weight gain of almost 0.5kg/day.

Forage crops such as kale are also suitable for replacement weanling heifers during their first winter, but should only be used on dry soils where there is a limited chance of damage and poaching.

Forage crops are high in crude protein (CP), around 18% CP which will help with the growth of the animal as weight gains of over 0.5kg/day are achievable from these crops.

These heifers should be supplemented with a bolus to ensure sufficient intake of essential minerals, along with some straw for a bit of roughage and fibre in the diet.

Lighter heifers should be prioritised to go out to grass first in February, as they will gain up to 1kg on good spring grass.

However, farmers should not rely on good weight gains in the spring to make up for poor performance this winter, as by following these key steps, the heifers should be on target and given the best chance to succeed within the herd.