Calf rumen development is influenced by early diet choices, with significant long-term effects on nutrient absorption and overall health. According to recent guidance, feeding starter grain to calves from an early age promotes the growth of rumen papillae, which are important for nutrient uptake as adult cows.
“Ruminal development as a calf dictates long-term rumen health and function as an adult, lactating cow. Increased ruminal development as a calf results in better developed rumen papillae (“finger-like” projections that line the rumen and help to absorb nutrients) (Figure 1), which leads to better nutrient uptake. The more nutrients a calf can absorb, the more she can utilize said nutrients when it comes to growth and everyday metabolic functions,” according to experts.
Starter grain is often introduced within the first week of life, sometimes beginning on day one. Although initial intake is low, unrestricted access is recommended. “Grain can be offered within the first week of life, and it is very common for calves to receive a grain allowance starting on day one. Calves do not consume a large amount of grain at first, but it is important that their intake is never restricted.”
To minimize waste, small amounts—about a handful—should be given initially because larger portions may spoil before being eaten. As calves’ appetites grow, their grain allotment should increase accordingly.
The type of starter grain also matters. There are two main categories: textured and pelleted grains. Textured starters usually contain various grains mixed with pellets and molasses for palatability; pelleted grains provide uniformity in size and nutritional content and reduce feed sorting.
Protein content varies among starters, generally ranging from 16% to 24%. Larger breeds or those fed milk replacers lower in protein may benefit from higher-protein starters.
“Calves usually prefer textured starter grain (Cullens, 2018), which is a mixture of various grains and pellets. Molasses is a common binder in most textured starters, and it also helps to increase palatability.”
“Pelleted grain allows calves to have more uniform uptake of nutrients, since every pellet is virtually the same. This also reduces sorting, as every piece is consistent in terms of size, texture, and moisture. Pelleted grain is potentially more digestible due to how it is processed (Litherland et al., 2014), and it will also attract less flies since there is no molasses coating.”
Hay can help maintain healthy rumen pH levels by balancing acidity caused by highly digestible starches found in pelleted feeds. “Feeding hay can help balance the rumen pH and keep the environment from becoming too acidic. Pelleted grain is more likely to cause rumen acidosis due to the ‘high levels of readily digestible starch’ (Jones et al., 2022), so hay can be fed as a buffer to help maintain a healthy rumen pH.” It’s advised that hay be introduced once calves eat about five or six pounds of grain per day or reach seven or eight weeks old.
Water access should begin on day one without restriction because water aids both hydration and papillae development in the rumen rather than just passing through the digestive system with milk feeds.
“Water should be offered on day one of life to all calves, and should never be restricted. The water that calves consume via milk goes to the abomasum, not the rumen. Plain water will go directly to the rumen and will aid in papillae development (Amaral-Phillips).”
Clean water supports hydration needs while playing an essential role in developing proper digestive structures during early calfhood.
