Nutrition
Nutrition Articles
Body Condition Score shows Nutritional Status
For many decades Body condition Score (BCS) has been the measure of a sufficient nutritional program for beef cows and heifers on pasture. However it is an ‘after the event’ measure meaning that in a failed monitoring situation the metabolic process of mobilizing body reserves has already taken place. Beef cows face dynamic and highly variable nutritional environments that periodically are inadequate in meeting nutrient and energy requirements. Nutritional management during high metabolically stressed and key physiological states can lead to increased or decreased metabolic efficiency.1 When cows fail to get the nutrients they need, first energy reserves are used, then if the event is severe protein stores are affected. In most cases cows grazing spring pastures are going to be okay. Fresh grass has protein levels above 20% and is low in fibre. As the pasture moves from vegetative growth to midseason, protein drops to 10% to 12% and finally to mature status where protein drops to around 6% to 7%. In addition, soluble sugars and starch are present making the early vegetative growth pasture forage high in energy. Lactating cows on early pasture will consume 30 lb. or more of dry matter (DM) or 100 lb. to 110 lb. of fresh forage. This material provides nutrients generally in excess of what is required so the concern begins as the pasture fades, suffers from drought or is overgrazed.
1350 lb. cow in month one and two of lactation needs about 20 Mcal. of Net Energy and 1400 grams (3 lb.) of protein daily. The actual number depends on body weight, milk production and weather conditions but it represents an average animal. Achieving this intake is no problem as long as the pasture is stocked accordingly and the animals are moved when the stand is diminished. Animals with smaller rumen capacity are not able to eat as much as bigger animals so will show negative energy balances more quickly than larger animals. As the grazing season continues there is a risk for animals to fail to eat enough to meet nutrient requirements and begin to slide in BCS if the stand is too thin. At this point, supplementation can prevent negative effects on pregnancy and allow the animal to keep a positive energy balance. Action here can save pregnancy and build body reserves for next year’s calving. Supplementing extra forage also gives the opportunity to add critical minerals such as zinc and copper. Early action is best, and both minerals help reproductive performance and immune response. Using a Highline mixer can accomplish the accurate mixing and delivery of supplemental feed without over feeding expensive rations.
Supplementation strategies may be utilized to improve metabolic efficiency during nutrient and environmental challenges. Droughty conditions have been the norm over the past years creating too many open cows and heifers. Weekly surveys of animal BCS pays dividends in higher conception rates and more calves carried to term when extra feed is supplied early before BCS deteriorates.
As a guideline, a BCS of 2.5 (5 US scale) is acceptable but drought can quickly reduce that score to 2 (4 US scale) which causes negative effects in animals at risk. Monitor the herd and the weather and act in advance to maintain a positive energy balance in the animals.
1.
Sustainable and economically viable management options for cow/calf production through enhanced beef cow metabolic efficiency, J Travis Mulliniks, Joslyn K Beard, J Anim Sci . 2018 Dec 14;97(3):1398–1406.