When Do Beef Calves Start Eating Grass? A Guide to Calf Nutrition

Raising healthy, thriving calves is crucial for any cattle operation. An important part of calf development is the transition from milk to solid foods like grass. But when exactly do beef calves start eating grass?

Understanding the timeline of a calf’s nutritional needs provides insights into how to best support growth and performance. In this guide, we’ll cover

• The calf’s initial diet of milk
• The development of the rumen
• When interest in grass emerges
• Making the switch to solid foods
• Methods for monitoring grass intake
• Impact of nutrition on growth

Let’s explore the key milestones that signal a calf is ready for grass

A Calf’s Early Milk Diet

At birth, a beef calf’s diet consists entirely of its mother’s milk. The first milk produced, colostrum, provides vital nutrients and antibodies that strengthen the newborn’s immune system.

After the colostrum period, the calf continues to nurse milk to receive protein, carbs, fats, vitamins, and minerals needed for growth and health. Milk remains the sole source of nutrition for the first few weeks of a calf’s life.

The Role of the Developing Rumen

The rumen is one of the four compartments of a cow’s stomach and allows for digestion of fibrous feeds like grass. But the rumen doesn’t fully develop until a calf is a few months old.

In newborn calves, the rumen is inactive and small in size. It gradually grows and starts functioning as the calf begins consuming solid feed. By 8-12 weeks old, the rumen takes over as the main source of digestion.

When Do Calves Start Interest in Grass?

Calves start to show interest in grass and other solid feeds around 2-3 weeks of age. They may begin nibbling on grass or hay, but milk remains the primary source of nutrition.

This early interest allows calves to explore solid feeds, while still relying on the nutrients in milk. But grass intake is minimal at this stage while the rumen matures.

Making the Switch to Solid Feeds

By 4-8 weeks old, the rumen has developed sufficiently for calves to start transitioning to solid feeds. High-quality forages like grass hay should be offered in increasing amounts.

Gradual introduction allows the rumen time to adapt. Milk can be reduced over time until calves are fully weaned by 2-3 months of age.

Methods for Monitoring Grass Intake

Once calves have access to grass, it’s important for cattle producers to monitor consumption to ensure adequate nutrition. Helpful methods include:

• Observing grazing time and behavior
• Tracking average daily weight gain
• Body condition scoring every 2-4 weeks
• Measuring pasture availability and quality

Any decrease in performance could indicate issues with grass intake. Adjustments to the diet can then be made.

Nutrition Needs for Growth

Growing calves have specific nutritional requirements to support development. Key needs include:

• 16-18% crude protein in diet
• 60-80% TDN for digestible energy
• Calcium, phosphorus, and vitamin levels

Grass, hay, and other forages should provide quality protein and energy. Grain or supplements can balance the diet when forage alone is lacking.

The Takeaway

Understanding the timeline of calf nutritional needs is key for cattle producers. While milk satisfies requirements at first, gradual introduction of grass and other solid feeds is ideal around 4-8 weeks as the rumen matures.

Monitoring forage intake and growth patterns helps ensure calves get adequate nutrition from grass. With proper management across each stage, calves will be set up for healthy rumen function and lifelong performance.