I have visited different pasture-based dairy farms and I have seen how cows get fed different types of feed. There are proper diet plans for all types of cows on the farm. Farmers use different models to plan for feed rationing and even divide the herd during feeding to make sure that each gets adequate feed. In every business or aspect of life it is always important to get satisfying results from the work you put in, and dairy farms are no exception to this. I have learnt that diet formulation for dairy cows requires knowledge of the feed and nutrients required by the cows to produce milk and maintain all the other functionality of the cows. Farmers need to have a knowledge of the quantity of nutrients that come with each feed and plan how much to offer each cow. Dairy cows not only use feed consumed for milk production but for other functions such as body maintenance, growth, and reproduction. Hence proper planning and knowledge is important to achieve this balance. Essential nutrients needed by cows include water, protein (amino acids), carbohydrates, fats, vitamins, and minerals.
In this article I would like to discuss the importance of nutrients required by dairy cows for proper functionality:
Milk is made up of 87% water and therefore making it very critical for milk production. Interestingly, water makes up 56 – 81% of total body weight in the dairy cow and between 68 – 72 % in the pre-ruminant calf1. Water is essential in transporting nutrients around the body, to regulate temperature, for body insulation and removal of waste. The biggest source of water in a cows body is through free water intake and second being feed water. The amount of water that should be given to cows daily depends on various factors such as environmental temperatures, water quality, animal activity such as walking distances and even dry matter intake.
2. Protein and amino acids.
Protein is required by dairy cows for metabolic functions such as growth, lactation and reproduction. Dairy cows require amino acids for milk production, mainly for the production of enzymes and milk proteins. The protein in cow feed is normally referred to as crude protein, which is an estimation of protein based on the amount of nitrogen(N) content in the feed. Protein contains 16% N, so crude protein can be calculated by multiplying the N content in the feed by 6.25. Some examples of feed that contain protein are soybean meal, canola meal and corn gluten meal.
Carbohydrates are the biggest energy source for cows and they make up about 75% of plant dry matter. Carbohydrates are the foundation for the production of milk sugars (glucose) and the production of fat, which are both essential milk components. Good quality pastures contain carbohydrates that are easily broken down in the cows stomach and can provide the same energy levels obtained from concentrates and supplements. Therefore, for sustainable feeding, maximum pasture intake is always advised. To complement the forage to meet the full carbohydrates requirements, feed such as soyhulls, corn and mollasses can be fed to dairy cows.
4. Dietery fibre
Fibre is important for rumen health and increasing milk fat percentage. A decrease in milk fat percentage can act as a good indicator of low fibre intake in cows only when the other nutrients are offered as per their requirements. The rumen, which is the cow’s stomach, requires fibre particles of 2 – 5 cm long to promote cud chewing and rumination to produce saliva2. The released saliva acts as a buffer to maintain the pH levels in the rumen and this promotes the growth of rumen microbes2. To measure how much energy will be derived from feed, that can be used by a cow, an acid detergent fibre (ADF) has to be calculated. A feed that has high ADF has low digestibility of the fibre fraction and low available energy5. The plant’s structural components are the source of neutral detergent fibre (NDF). Feed with high NDF provides low calorie filler. It is important to know the ADF and NDF percentages because they can accurately predict forage intake as it relates to bulk5, in other words, how much an animal will eat before it’s stomach is full. These figures are also key for measuring energy levels and animal performance5. Wheat and oats are some of the feed that contain fibre that can be fed to cows.
Vitamins are not needed in large portions for cows but their deficiency can affect the health of the cow and compromise the milk production. Vitamins are either fed to the cows through other feed components or must be synthesized by microorgansims in the digestive system and then absorbed by the host animal. Defiecieny in vitamins can cause problems like rickets and or scurvvy from a vitamin D and C deficiency, luckily these two can be synthesized by the cow3. For example, vitamin C can be synthesized from the kidney and liver. Two vitamins that are reported to be of absolute dietary requiremt for dairy cows are vitamins A which is for gene regulation, immunity and vision and vitamin E which acts as an antioxidant1. These vitamins are normally obtained from fresh grazing pasture especially if there is a multispecies pasture system, where you will get a combination of grasses such as lucerne, ryegrass, and chicory, to name a few.
Minerals such as calcium (Ca), magnesium (Mg) and phosphorus (P) are elements needed by dairy cows for various bodily functions from structure and nerve impulses to osmotic balance2. Mineral nutrition is essential for the success of the lactation. Varied amounts of both macro and micro minerals are used as milk composition, and some are used for the cow’s health3. To improve the immune system of the cow so that it can withstand some diseases or any infections. Minerals can be obtained from grazing pastures, can be supplemented to cows through water or through straight supplements such as licks.
This article emphasised the importance of knowing the nutritional content of feed fed to dairy cows. It is important that this feed gets converted efficiently into good quality milk. This can be obtained with proper feeding strategies that involves balanced diets and proper feed rationing. Inadequate nutrition is a major cause of low live- weight gains, infertility and low milk yields and other health issues in animals. For sustainable feeding, maximum pasture intake is the most important principle to focus on and then supplement when there is a need. Multispecies pastures offer the cheapest food source filled with the best nutrition for cows.
- https://dairy-cattle.extension.org/update-on-vitamin-nutrition-of-dairy-cows/ https://dairy-cattle.extension.org/update-on-vitamin-nutrition-of-dairy-cows/