Summer Nutrients for Productive Cows
Published on Tue, 05/21/2019 - 2:08pm
Summer Nutrients for Productive Cows
By Bruce Derksen
For many producers that send cows to early summer pasture, nutrient levels are not a large concern as they assume lush green grass means a cow has everything it needs, but this is not always the case. Requirements for specific minerals, vitamins and proteins will vary with stages of pregnancy, breeding status, age and body reserves, but cows still require appropriate supplementation at all times of the year. If there is a failure during the spring and summer, a cow’s reserves will be depleted leading to deficiencies which can be extremely difficult to correct.
At pasture turn-out, energy is one of the most critical nutrients for grazing and milking cows. While energy requirements peak at maximum milk production for a fresh or nursing cow, nutrient demand decreases with days in milk, to once again rise during the last month of pregnancy due to the development of the fetus. 70% of the fetus’s growth occurs in the last three months of pregnancy and a lack of energy and protein in this period is the most severe cause of poor reproductive performance.
Minerals and vitamins also play vital roles in reproduction, immunity, growth and milk production. While most cattle can survive on the levels of available pasture and forage, many cows are not receiving what they need to achieve the highest levels of production. A temptation for producers is to see lush green pasture, assume the existence of proper nutrient essentials and reduce or discontinue the addition of these vital requirements.
When supplementing grazing cattle, the objective should be to assess the seasonal moisture conditions of grass, attempting to balance any nutrient deficiencies in an efficient yet profitable manner. When farmers face numerous deficits, the use of a multi-nutrient mineral block can be the first step. A nutritionist or feed company specialist can help to decipher what is required and the best course of action.
In general, summer pastures have two stages of growth- spring vegetative growth and mature, or mid to late summer grass. With adequate rainfall and optimal temperatures, the nutrient content is highest during the spring’s new growth, but energy shortages can still occur with excessive stocking rates causing a lack of quantity. Forage energy may also be adequate, but problems can still result if the animals are not harvesting enough.
Cows also need salt and minerals in their diets but when they are on pasture, providing them requires attention. Barry Yaremcio, Alberta Agriculture livestock and forage specialist, states a 1300 to 1400-pound cow requires 35- 45 grams (1.2 – 1.6 oz.) of salt per day. For a guideline, a one hundred cow herd would use a 55-pound bag of salt-mineral per week. He went on to say, “Although cattle crave salt when they need it, they don’t have that sense when it comes to minerals. It’s up to us to provide a balance of what’s required. Cattle won’t seek out sources of mineral in which they are deficient.”
Minerals are loosely grouped into two categories: macro-minerals and trace or micro-minerals and are an extremely important part of cattle nutrition, playing a vital role in reproduction, immunity and growth. Of the macro-minerals (those present in greater concentration in the diet) phosphorus, sodium and chlorine are the most likely to be lacking under pasture conditions, and cobalt, copper, iodine, manganese, selenium and zinc are the most likely deficient micro-minerals. A complete mineral/salt/vitamin supplement will provide necessary levels of both macro and micro-minerals, along with salt and vitamins.
While most producers provide variations of mineral, salt, vitamin and protein supplements during winter and spring, many mistakenly see growing, green pastures as a sign to discontinue their use. This practice may reduce costs in the short run but can be very costly in the long-term outlook. Feed company specialists or nutritionists can help develop a plan to have protein, energy, macro and micro minerals plus vitamin requirements filled. Don’t wait for a wreck to happen because at that point, it could be too late.