Preparing calves for grass: A guide to successful weaning
A smooth transition to grass ensures that calves continue gaining weight efficiently, writes Laura O'Connell.
With St Patrick’s Day behind us, many calves will be close to weaning, and a farmer’s focus moves to transitioning calves to grass. Proper preparation is essential to ensure a smooth weaning process, minimise stress and promote optimal growth and health.
A well-managed weaning period enhances future performance and profitability in the herd, as well as helping prevent common health issues such as summer scour syndrome.
Here are the essential steps to ensure a stress-free transition:
Sudden shifts in diet, such as an abrupt change from milk to a forage-based diet, can lead to digestive disturbances and setbacks in growth rates. A steady intake of high-quality concentrate promotes rumen papillae development, which allows for better nutrient absorption when calves transition to grass.
Before weaning, calves should be consuming at least 1.5 kg of concentrate, such as an 18% protein calf muesli or calf pellet, for three consecutive days. The starch in the concentrate will help to drive papillae development. This ensures their rumen is well-developed and capable of handling a grass-based diet.
Make sure any concentrate is highly palatable. It should also be dust-free to avoid respiratory issues.
Calves often select the most palatable, lush grass, which lacks sufficient fibre. To slow down the rate of passage and promote rumen health, ensure they have access to roughage such as straw or hay. Straw is preferable to hay, as high consumption of hay will decrease the intake of concentrates, and the young calves will often develop ‘potbellies’. Straw provides structure and encourages proper rumination without interfering with concentrate intake. This will help balance their diet and reduce the risk of digestive upsets.
Water is one of the most overlooked nutrients, with many assuming that milk provides sufficient hydration. However, this is not the case, as milk bypasses the rumen and goes directly to the abomasum. Unlike milk, water enters the rumen, making the ideal environment for the fermentation of concentrate feed by rumen bacteria. This process is essential for early digestive development and overall growth.
Clean, fresh, ad-lib water must be provided from birth to encourage rumen development, concentrate intake and increase daily weight gains. As a general guideline, calves require five litres of water for every 1kg of concentrate which is consumed, in addition to their milk feed. Ensuring a consistent water supply will help maximise growth rates and set calves up for a smooth transition to a solid diet post-weaning.
The main goal of calf rearing is to set replacement heifers up for future lactations, ensuring they achieve key weight milestones to maximise productivity and profitability. These targets include doubling their birth weight by weaning, reaching 60% of their mature weight at breeding, and calving down at 24 months at 90% of their mature body weight.
A smooth transition to grass ensures that calves continue gaining weight efficiently. Balancing their diet with high-quality concentrates, fibre sources and appropriate minerals supports optimal conversion rates and prevents issues related to nutritional deficiencies.
Stress is known to have negative impacts on health and performance. While stress can’t be completely eliminated, there are ways to minimise it through management.
One way is to vaccinate and dehorn calves before weaning. These procedures can be stressful, and performing them well in advance of weaning allows calves to recover fully before transitioning to grass.
Parasitic infections can significantly impact calf performance. A strategic worming plan should be implemented based on veterinary advice and faecal egg count monitoring. A well-timed dosing schedule helps maintain high feed conversion efficiency and prevents setbacks in growth rates.
Scour is a leading cause of calf mortality, accounting for nearly 30% of calf deaths while also hindering growth and performance as well as increasing workload for farmers. Prevention is always better than cure, and proactive management can significantly reduce the risk of diarrhoea in calves.
One scour which is becoming a lot more common in recent years is summer scour in weaned calves, characterised by the rapid onset of severe diarrhoea. Affected calves can deteriorate quickly, losing weight and condition at an alarming rate.
Symptoms of summer scour include:
- Rapid weight loss;
- Diarrhoea;
- Lethargy;
- Inflammation and scabbing around the mouth, making it painful to eat.
Despite extensive veterinary and laboratory postmortems, no infectious agent has been definitively linked to summer scour. Instead, evidence suggests that lush, low-fibre pastures and selective grazing habits contribute to an overly acidic rumen environment, leading to digestive disturbances.
Calves with an underdeveloped rumen are at a higher risk of developing summer scour. This is why a well-planned weaning process is crucial:
- Ensure adequate concentrate intake before weaning;
- Provide a source of roughage;
- Avoid sudden dietary shifts;
- Monitor calves closely for early signs of digestive distress.
To sum up, transitioning calves to grass successfully requires careful planning and attention to detail. By focusing on diet, fibre intake, worm control, and gradual adaptation, farmers can minimise stress and health issues, ensuring calves continue to thrive post-weaning. Taking proactive steps now will pay dividends in healthier, more productive animals in the long run.
