Our main objective in developing a diet, whether grass-fed or conventional, is to make sure our cows are getting the proper nutrients, to be healthy cows. We formulate diets with the help of our nutritionist, who is specialized in dairy nutrition. On our farm, we have over 10 different diets. Depending on the cow’s age, milk production, and gestational period, she will require different food.
Modern Dairy Cows Diet Formulation
The modern dairy cow is an athlete. Through years of genetic progression, modern dairy cows today are very different than cows from 50 years ago. Cows today have genetics that makes them capable of producing more milk, resulting in her need for a better diet to perform. Our nutritionist will develop a ration that has the right mix of Energy, Protein, Fat, and Fibre to meet her needs. Too much or too little of one of these macros will have adverse effects on milk production or, more significantly, her health. Energy is one of the most important components of the diet. Peak energy demand is just after the cow has had a calf. She needs a lot of energy to produce colostrum for her calf and to maintain her health through recovery. In contrast, a cow that is pregnant, but in her non-milking resting period of the year, will require far less energy.
Most grains fall into one of two categories for a cow – protein or energy.
The most common energy sources fed to cows would be grain Corn and Barley. With cows eating only 3-5% of their body weight in food every day. We must make sure that she is eating the right ratio of food, she can’t eat enough grass to fulfil her energy needs. We complement forages (grasses, hay, silage) with grain to increase the amount of energy she consumes. If she is short in energy series of events happen. For a short period, her body will metabolize body fat as an energy source to maintain her milk production. Once her body realizes the energy source is not coming back, she will begin to reduce her milk production and turn off her reproductive system.
Too much grain causes the primary compartment of the stomach, the rumen, to become too acidic and the essential balance of fibre and starch digesting bacteria to fail. This results in lower milk production and, in severe cases, a sick cow. To avoid situations like this, we make sure that the diet is balanced with enough hay or silage (forage). This balance also makes sure that she continues to chew her cud. (regurgitating her food and chewing it more) This is her natural way of combating acidity.
The most common protein sources for cows are Canola Meal and Soyabean Meal. These products are the by-products left after vegetable oil is extracted for human consumption, leaving it abundant in protein. Proteins are made up of long chains of amino acids. Modern dairy nutrition balances the actual building blocks she needs for protein in her diet by balancing individual Amino-Acids. These amino-acids serve many different purposes in the cow and are essential for milk production, body growth, reproduction and all other aspects of continued health. Some grasses and legumes (alfalfa hay) provide protein to a cow’s diet. These forages cannot provide all the amino acids needed for a modern dairy cow. We supplement with quality proteins like Canola meal and Soybean meal to make sure she is getting what she needs.
Fibre + The Rumen
A cow has 4 compartments to her digestive system, also known as 4 stomachs. The Rumen, Reticulum, Omasum and the Abomasum. The last of these is the most like a human’s stomach. The biggest of the 4 and the first in the process of digestion is the rumen. Fibre is an essential part of a cow’s diet, being a ruminant, she needs fibre to ‘ruminate’ (regurgitate her food). Her ability to ruminate results in a stable, healthy rumen, keeping the pH in an optimal range to maximize health and productivity. In the rumen, protein and energy are produced for her body’s needs through the fermentation of her diet. A properly developed diet has the right balance of fibres and grains to give the fuel to do this process. Forages such as grasses, alfalfa, corn silage (entire plant fermented) are good sources of fibre.
With limited space in the rumen, overfeeding bulky fibre will not leave room for anything else. Underfeeding fibre will create too much acid if that space is filled with grain leading to an unproductive and unhealthy cow. We also need to leave room for protein, water and fat.
The final most crucial component in the diet is water. Our cows must have free access to high-quality water. Water makes up to 70% of the cow’s body weight. When she is producing milk, 87% of the milk that she produces is made up of water, so she needs to replenish that water regularly. The primary source of water would be through drinking water, she would get a small about through eating forages.
Next post we will explore why feeding a grass-fed diet is challenging.