The first 12 weeks of life is a critical period for rumen development in calves. What you feed your calves will directly affect the rumen development. Calves require adequate nutrition support for rumen development. Identifying the right grain and hay balance for your calf nutrition program will help ensure they live up to their genetic potential.

Milk only diet limits nutrient absorption

• Calves that are fed milk only diet will have limited rumen development.

• Nutrients will bypass the rumen and go directly into the abomasum via the reflexive closure of the reticular groove.

• This will cause the abomasum to increase in size while the rumen remains small with restricted development of rumen wall and papillae.

Waiting to introduce forage

• Calves fed hay or forages prior to weaning will begin to ruminate, have a greater flow of saliva into the rumen and have better rumen muscle development of the rumen wall.

• However, this does not provide enough concentrations of volatile fatty acids (VFAs) to promote rumen papillae growth, which is crucial for a functioning rumen.

• Studies have shown that calves fed a high quality alfalfa hay diet, in addition to milk or milk replacer over a 12 week period had high growth rates, but minimal papillae development compared to calves fed only milk.

• If the calves are eating around 10 lbs of starter/day before 12 weeks, start offering small amounts of hay.

• There is no need for hay until that point.

Feeding calves grain

• Grain is a key element of calf rumen development because of its involvement in VFA production to support papillae growth.

• Studies have shown that calves fed milk and free choice grain over a 12 week period had larger papillae and a thicker, more developed rumen wall.

• Also, grain fed valves rumens were darker in colour due to greater vascularization, which allows for more VFA absorption into the blood stream.

• Provide a small amount of grain at 3 days of age and gradually increase the amounts until calves are eating 3 pounds per day for 3 days in a row during weaning.

• It is important to allow adequate water along the grain to create proper rumen environment.

• This will help support fermentation and VFA production, which will help stimulate rumen development.

• Look for a starter that is connected to the milk replacer by a special blend of ingredients.

• The consistent smell and flavours will help calves stay on feed, minimizing weaning slumps.