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Calf stress at weaning could affect future production

19 April 2020

There are two times in a dairy cow’s life that can be critical to maximising future milk production. One, as most of us know, is the transition period around calving. The other, which may be more surprising, is the weaning period way back when the cow was a calf between 45-60 days old.

Both time periods are stressful to the animal and a challenge for producers to manage. Researchers continue to explore strategies and companies continue to develop products to meet these challenges.

As early as 4 weeks old, the calf starts to transition from a monogastric into the ruminant that it will become. It is well recognised that starter grain intake is critical for rumen development and growth. Fresh water availability and consumption is directly correlated to grain consumption. High-quality hay can be important as well. However, particle length should be kept at 2-3 inches and keep in mind that too much hay may limit grain consumption. An 8:1, grain to hay (by weight) ratio has been suggested as ideal to provide adequate energy while starting to expose the calf to roughage. Between 4-8 weeks of age, the microbial populations in the rumen will begin to stabilise and by 8 weeks the goal is to have a calf that has at least doubled in body weight since birth.

Many farms will wean dairy calves around 8 weeks of age to transition from an expensive, labour-intensive liquid diet to a diet of grain and roughage. Stressors on the weaned calf include not only diet change, but likely the calf will also experience a change in housing and social structure. In addition, the calf may even be transported over long distances to arrive at a new housing facility. These stressors can limit feed and water intake and make the calf more susceptible to diseases, such as coccidiosis and bovine respiratory disease (BRD, pneumonia). To mitigate such stressors, researchers and consultants have suggested a step-down strategy to milk feeding and are investigating the benefits on group housing.

In addition to management strategies, there are several feed additives to consider. Electrolytes will help the calf consume enough water and stay hydrated at the cellular level. Yeast products can help stabilise rumen pH and promote the proper ratio of starch to fibre-digesting bacteria. Ionophores and coccidiostats help prevent and control infection from Coccidia eimeria parasites. Direct-fed microbials (DFM, probiotics) will help build the ideal microbiome in the calf’s gut.

There are many of these feed additive products to consider, but not all are created equal. Work with your veterinarian, nutritionist and other consultants to include products that are science based, research backed and will specifically work in your management system. Give challenged calves the resources they need to overcome stress at weaning time and they will perform well when they join the milking herd.

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