Dr Charles Marwood: Calving at two boosts profit margins

Many studies across both dairy and beef sectors have consistently found that heifer calving age drives profitability. Targets of 24 months of age at first calving are achievable, with a lot of farms already hitting these targets annually. Calving at two years, means those heifers start to generate income, whether from milk or rearing their calf. Calving at 30 or 36 months involves higher rearing costs, in housing and feeding until those animals start to earn their keep.

Growth rates

Calving at 24 months means bulling at 15 months or younger. This is easily achievable, but good growth rates have to be maintained from birth. Growth rates of 800-1000g/day are the target. Major threats that impact growth rates often occur early in life, with neonatal scours and pneumonia being very common. These risk factors are well understood, and prevention is far better than treatment or cure. Measuring growth rates provide an indication of when calves are thriving. Where growth rates are not being met, investigation is required to find out underlying health or nutritional problems.

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Calving heifers at two years of age is achievable provided their health and nutritional requirements have been met

Colostrum

Calf colostrum quality, quantity and timing of the first feed is fundamental to calving having the best possible start in life, ensuring calves have an active immune system from the first day of life. Four litres, as soon as possible after birth and housed in a clean, dry environment will give the calf the best possible start.

Neonatal scours

Rotavirus, cryptosporidium and coronavirus are very common causes of scour in calves under a month of age. Highly contagious and spread via the environment, hygiene and vaccination are key to control. Calf scours are treatable with effective rehydration therapy, but the knock-on effect of gut damage reduces growth rates and immunity, making other diseases more likely.

Pneumonia

Primary viral and bacterial pneumonias are common in calves under a year of age. Management factors, housing, environment, immunity and vaccination all affect the severity of this common problem. Pneumonia outbreaks have a huge impact on calf health, not just the cost of calf mortality but even greater cost on long-term growth rates.

Weaning

Weaning dairy calves at eight-10 weeks should not impact growth rates if the nutritional needs are being met. When calves are born, their digestion is designed to digest milk, which starts its process in the fourth stomach, the abomasum.

The second stomach, the rumen, is very underdeveloped at this stage but must be fully functioning before weaning occurs and capable of fully digesting a forage-based diet. For weaning to occur, without impacting growth rates, clean palatable forage, barley straw, hay or haylage must be available to calves from one week of age. The long fibre stimulates the lining of the rumen to develop, together with free access to fresh water and starter pellets or ration. This seeds the rumen with the right balance of fibre, carbohydrate and protein to feed the rumen flora, stimulating rumination and fermentation.

Slow reduction in milk volume encourages higher dry matter intakes and maintains growth rates once milk has been removed from the diet all together. Post weaning scours are possible if milk is withdrawn too quickly before the rumen has fully developed.

Nutrition

Once calves have been weaned, their digestion is dependent on the rumen receiving a balanced palatable diet. The rumen requires long fibre, fermentable carbohydrates and protein to ensure rumination takes place, with a balance of rumen flora to help digest their diet. The rumen can take up to two weeks to adapt to a change in diet, as the biome adapts to different constituents. Feeding Total Mixed Rations or TMR’s gives the rumen the most stable conditions to work efficiently. With a stable pH and flora, the most efficient feed conversion and consequent growth rates are achieved.

Grazing dairy heifers on poor pasture will have a significant impact on growth rates and onset of puberty, so care must be taken to manage their nutrition until they have been served and confirmed pregnant.

Heifer selection

It is important to breed from the best heifers, these will be the best grown for their age and free from disease. Consider genomic testing dairy heifers as this will influence whether they are bred to dairy or beef semen.

Pre-breeding checks before bulling is also useful to monitor pelvic size, identify non-breeders, freemartins and heifers with under-developed ovaries. Synchronization and AI is a powerful management tool to ensure heifers calve in tight batches, choosing the best sires for easy calving and options of sexed semen too.

Retaining heifers with the best conception rates is also valuable, these will calve early and more likely to hold to service in subsequent years. Ideally, giving heifers only two services and retaining those pregnant will keep the most fertile in the herd and keep calving patterns tight.

Calving heifers at two is very much achievable if they get a great start, are kept free from diseases and receive good balanced nutrition from the outset. These heifers will be the most profitable and have the smallest carbon footprint, which also saves the planet.