Agribusiness News August 2024 – Inputs: Dairy Heifers

When you think of inputs, dairy heifers don’t instantly spring to mind, but they are a key input into the milking herd; accounting for around 20% of total production costs.

Data from the NMR 500 Herd KPI Reports over the last few years show that 17% of heifers fail to reach their 2^nd lactation – the point at which they start to pay back their rearing costs.  Therefore, to ensure greater longevity in the herd, it is important to focus on ensuring that health and productivity targets are met throughout the rearing process.

Getting it right from the start  

The importance of early life nutrition cannot be emphasised enough as the growth rate during the milk feeding phase of a heifer calf is closely correlated to first lactation performance.

While the importance of colostrum is well documented, recommendations on milk feeding rates are now to feed 15 to 20% of body weight, with a typical milk replacer inclusion rate of 15%.  It is now not uncommon for dairy heifer calves to be fed in the region of 8 to 10 litres of milk per day and weaned later than the typical 8 weeks of age, at around 10 weeks or more.

Feeding more milk means higher weight gains, with stronger, healthier calves.  Later weaned calves tend to cope better with the stress of weaning, have less of a post-weaning growth check and less disease issues.  Essentially, the more milk the better!

Monitoring growth rates

Have a target for heifers to reach a certain weight by a certain age for breeding.  Heifers should be 55-60% of their mature body weight at service and 85-90% of their mature weight when they calve down for the first time.  For example:  For a mature cow size of 650kg, the target weight for a heifer at point of service would be 360-390 kg and between 550 and 585 kg at point of calving.  To achieve this, heifers need to grow at a minimum average of 0.7-0.75kg/day from birth to calving, assuming calving at 24 months and a 40kg birth weight.

Weighing heifers at key times will help ensure growth rates are on track to reach target weights and will identify periods where heifers are not growing as well,  enabling improvements in feeding or management to be made.  As younger animals are more efficient at converting feed into growth, the pre-weaning period and up to service is where to push for good growth rates of up to 1kg per day.

Selecting the best heifers for breeding

If aiming to calve on average at 24 months, start serving at 13-14 months to allow for any heifers not holding to first service.  Ideally, any heifers that do not hold to their 2^nd service should not be kept as replacements, as they may not be as fertile as cows.  Genomic testing at birth or at least by 10 months of age is a very useful tool to select the best heifers genetically for breeding.

Goals from service to pre-calving

During the service to pre-calving period, the aim is for steady growth and for heifers to continue to grow frame, not fat.  To maximise embryo survival, there should be no dietary, group or housing changes for six weeks post-service.  Heifers should be in a body condition score of 3 to 3.5 when moved to the pre-calving group, with no change in condition until calving.

Minimise Stress

Heifers experience a lot of stress over the pre-calving period and transition into the milking herd.  Stress can be minimised in the pre-calving period by moving heifers to the dry cow group 60 days before calving.  Ideally move them in pairs or small groups and ensure that the dry cow group is stocked at no more than 90% capacity based on feed space.  To maximise intake and rumen fill, feed to allow for a 5% refusal.

From a housing perspective, ideally heifers should be housed separately during lactation, or at least for the first four months to get them over the critical risk period and back in calf.  This helps reduce competition at the feed face, allowing heifers to grow and reach peak yield before having to compete with older cows.  If a heifer group is not possible, then heifers need to be well grown to compete with the cows.  Ensure sufficient feeding and lying space for the whole herd, move heifers in groups or pairs into the milking herd and ideally, move in the afternoon.  It can take heifers up to three weeks to adjust especially as they have the stress of being milked for the first time as well!  If possible, familiarise heifers with the parlour before calving.  Consider walking them through a few times with the dry cow group for a small amount of feed and then through the footbath on the exit.

Top tips for heifer rearing

• Do not scrimp on milk! Review milk feeding rates and milk replacer inclusion, aim to feed a minimum 1kg CMR/day.
• Record and review health data regularly with your vet. Can improvements be made to nutrition, housing, management etc to reduce scour and pneumonia rates?
• Monitor growth to ensure heifers are hitting weight targets and are on track for service at around 13-14 months.
• Look after heifers in the pre-calving period by reducing social stress as much as possible and providing ample feed and lying space.
• Consider a separate heifer group post-calving. If not possible, having sufficient feed and lying space becomes even more important.

Lorna MacPherson, lorna.macpherson@sac.co.uk