During the winter, feeding can be a challenge depending on facilities and feed availability, but it is an area that should not be ignored as both fertility and calf health depend on getting it right.
In-calf heifers have many demands as they continue to grow at about 0.5kg/day, as well as develop the calf, prepare for lactation and prepare to get back in-calf.
When feeding these animals, we need to meet their requirements over the winter with the aim of optimising BCS (body condition score) at calving and producing a healthy, live calf.
See also: How to improve beef rations for better colostrum at calving
1. Body condition
In-calf beef heifers ideally want to be a BCS of 2.75-3 at calving and weigh 85% of mature cow bodyweight.
If heifers are too thin at housing and more feed is required to improve condition, there is the risk that this encourages calves to get too big, which may cause calving difficulties.
If heifers are too fat at housing and feed is restricted over the winter, this can have an impact on the growth of the heifer and calf development.
Therefore, minimising the change in condition is advised and BCS should not differ by more than 0.5 over the winter.
This will have multiple benefits, including reducing the risk of calving difficulties, optimising colostrum quality and milk production, and reducing the interval to oestrus and the heifer’s ability to get back in-calf for a 365-day calving interval.
In the last month prior to calving, the focus should be put on feeding for colostrum and milk production because feed in this period will be naturally diverted into udder development.
During this period, ensuring an adequate level of effective rumen degradable protein is essential to drive microbial protein production, which is required for milk and colostrum.
Ensuring colostrum quality and quantity at calving is the driver for calf health and development through to weaning.
Housing and management of in-calf beef heifers are as important as the feed itself.
Minimising stress throughout the winter-feeding period and pre-calving will reduce the risk of abortions, and health issues around calving as well as optimising growth and calf development.
Feed space should be at least 750mm a head to allow every animal to access feed easily, regardless of whether they are housed in cubicles or loose housing.
Ideally, cubicles should be stocked at 90% occupancy and heifers should move to loose housing two weeks before calving.
Loose housing area will be dependent on the weight of the heifers, but about 3.5-4sq m bedded area a head or a total area of 5-6sq m a head should be provided.
In-calf heifers should ideally be housed separately from mature cows to allow targeted feeding and reduce the risk of bullying.
3. Feed requirement
Winter rations will be predominantly forage-based. In most cases in the UK, this will be silage or haylage, although wholecrop, maize, or straw may also be used.
The forage available on farm should be analysed to give an indication of the protein and energy available.
For most of the winter, the requirement will be for maintenance and 0.5kg/head of growth on average. For example:
Maintenance = 5 + 0.1 x liveweight
Growth = 1.5 x maintenance, pregnancy = about 5MJ
Therefore, if heifers are 500kg, on average, they will have a requirement of about 88-90MJ metabolisable energy (ME) a day.
During mid-pregnancy, the crude protein requirement of the diet is about 11%, but this ideally wants to be increased to 14% in the last three to four weeks pre-calving.
In-calf heifers weighing 500kg are likely to have a dry matter intake of roughly 10kg.
Silage 35% DM, 10.5MJ ME, 14% CP
Straw 85% DM, 6MJ ME, 4% CP
Wholecrop 40% DM, 10.5MJ ME, 9.5% CP
Protein supplement (for example, rapemeal)
Note: DM = dry matter; ME = metabolisable energy; CP = crude protein
4. The importance of protein
A protein supplement will be useful close to calving to support colostrum and milk production.
Reducing the straw and increasing the silage closer to calving will also help increase the energy density of the diet and the overall protein level to support the heifer through calving and get her ready for lactation and subsequent service.
Mineral supplementation will also need to be considered; this may already be provided if a compound (pre-mixed) feed is used rather than a straight protein supplement.
Important elements at this time are calcium, magnesium, selenium, and iodine.
If there is a mineral imbalance or extra stress around calving, especially with calcium and magnesium, there is a risk of hypocalcaemia (milk fever), although this is usually more of a challenge in older cows.
If hypocalcaemia occurs, even at sub-clinical levels, this can slow the progress of calving, increase the risk of retained foetal membranes, increase the risk of metritis, and lower the immunity of the heifer at calving.
All these factors can reduce the viability of the calf being born and have a negative impact on fertility for the following service period.
Poor colostrum quality and quantity will affect the ability of the calf to develop immunity by reducing the protection the calf receives.
This can increase the risk of scour and pneumonia in the first few weeks of life as well as potentially reducing growth rates through to weaning.
Overall, it is important to ensure the heifer is managed and fed to minimise stress and changes while ensuring the heifer’s requirements are met.
Concentrating on this important period in these important animals will provide longevity to the herd as well as improve performance and therefore profitability longer term.
This content has been produced as part of Farmers Weekly and AHDB’s new Maternal Matters series.
Maternal Matters is an AHDB initiative putting a spotlight on the importance of maternal performance in driving profitability in the suckler herd.
Find out more at ahdb.org.uk/maternal-matters