If managed properly, pasture-based programs can be designed to optimize cattle performance, improve forage and soil quality and minimize input costs, but pastures may need to be supplemented to ensure top performance.
Evaluating forage quality and quantity and then adding minerals and protein supplements to the mix can help producers reap the rewards of pasture-based production.
Mineral, protein deficiencies in grazing herds
One of the largest problems producers face when relying on pasture is mineral deficiency. Analyses from the USDA’s Animal and Plant Health Inspection Service (APHIS) consistently show that forages across the U.S. are typically deficient in macrominerals and microminerals when compared to beef cow requirements for production and maintenance.
N.T. Cosby, Ph.D., senior consulting nutritionist for Land O’Lakes Purina Feed, says cows on pasture may lack certain minerals and not show signs immediately.
Symptoms of mineral deficiencies in a herd may include: later conception rates, less thrifty calves at birth, reduced milk production leading to lower weaning weights and decreased herd immunity.
“Though these indicators are difficult to measure in most herds, failure to provide a quality mineral can lead to a gradual drop in performance that is challenging to recover from,” he says. “Building a cow herd’s mineral levels back to an optimal level requires time, patience and commitment to a sound mineral program before measurable improvements can be identified.”
Before creating a mineral supplementation plan, producers are encouraged to evaluate current nutrients supplied through the pasture for protein and energy levels.
During the growing season, forage quality will vary significantly. Similarly, a cow’s nutritional requirements fluctuate based on production levels and metabolic state.
A producer’s ability to match the production cycle of his cow herd to his environment and forage-growing season can pay dividends.
“For each cow, the last trimester and the first 60 days postpartum are the times of highest nutritional requirements,” Cosby adds. “If producers can plan their calving seasons and pasture management so that the highest nutritional needs occur when forage is the highest quality, supplemental nutrition needs will be reduced.”
Creating a supplementation plan
Forage tests can be used to evaluate pasture productivity and stored forages. Results can be put to use when designing a supplemental nutrition program to meet the cow’s requirements through the production cycle.
To balance nutrient needs and pasture resources, many producers work with nutritionists to design a protein supplement program.
The first step in many of the programs is implementing protein blocks. Cosby indicates that these products are most effective when forage quantity is adequate but forage quality is not sufficient to maintain desired levels of production in the mature cow.
Protein blocks can increase forage intake and digestibility by delivering protein in the form of ammonia and energy as carbohydrates to the rumen to enhance and improve microflora growth and efficiency.
“When this occurs, the micro-organisms in the rumen will more rapidly ferment the forage to provide energy to the cow,” he says. “Subsequently, forage rate of passage will increase and the cow will be able to consume more medium-quality to low-quality forage.”
In addition to protein and energy levels, pasture-based producers should monitor mineral levels in the ration.
Based on the time of year, industry programs can help producers determine specific minerals to monitor. For example, magnesium levels in spring-calving herds grazing previously fertilized cool-season grasses should be accounted for to prevent grass tetany.
Though the body stores of magnesium or calcium are adequate in most afflicted cows, mobilization of bone stores may not occur as rapidly as needed in older cows with heavy nutrient demands. When the risk factors are present, a high magnesium mineral is often recommended.
In this case, to lessen the possibility of tetany, seasonal high-magnesium minerals are recommended.
These minerals should be formulated with elevated levels of magnesium and calcium with no added potassium and necessary levels of intake to deliver the needed nutrients.
Magnesium sources are not palatable, so a complete mineral containing salt can help ensure acceptable intake levels. Mineral supplements should then be formulated differently for the rest of the grazing season.
Mineral supplementation is equally important through summer. Along with providing salt to improve proper function of the nervous and muscular systems, supplements with calcium and phosphorous help improve performance and longevity.
Because 99 percent of total body calcium and 80 percent of total body phosphorus are stored in the bones, skeletal stores of calcium and phosphorus are used to meet short-term deficiencies.
These minerals must be replaced, as long-term deficiencies of either mineral can cause bones to weaken and even break. A decrease in either or both can cause a decrease in efficiency of gain and lead to lower body condition scores.
During the summer months, cows are often relaying much of their energy into their calves. Low amounts of either calcium or phosphorous in the diet will reduce milk production.
A phosphorus deficiency can also delay mature beef cows from returning to heat following parturition and can delay puberty in developing heifers.
Calcium and phosphorus utilization is affected by both the amount of each mineral fed and the ratio of the two elements.
Research by Land O’Lakes Purina Feed has found that the optimum calcium-to-phosphorous ratio is about 1.5-to-1.
Though most grasses are adequate in calcium (with stored feedstuffs showing deficiencies), most forages are low in phosphorous late in summer and fall.
If byproducts are being fed to pasture-based herds, high phosphorous concentrations in the added feeds should be accounted for when selecting a mineral.
Taking it all into account, Cosby says creating mineral programs can be as complex as a producer chooses.
“Simple and consistent often works best,” he admits. “Most herd managers can simplify their mineral program to two or three mineral formulas for the year.” For example, a spring-calving herd in the Midwest would need a high-magnesium mineral in early spring followed by a quality mineral formulated for their area for the remainder of the year.
If the manager chooses to provide a fly control additive through the summer, he may deal with three mineral formulas.
“The best mineral is one that is manufactured by a reputable supplier, sold and serviced by a local feed dealer in the community and consistently provided to the cows by the owner,” Cosby adds. 
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Minerals for all seasons
Cattle mineral supplements represent a sizable investment per cow. To minimize unnecessary spending, producers should utilize mineral feeders and formulas that reduce shrink and waste.
In addition to less wasted product, production gains will increase by ensuring mineral is available and palatable when cows visit mineral feeders.
Ingredients in all-weather formulas are formulated with larger particle sizes that are less susceptible to loss during high winds.
Innovative formulas also prevent mineral loss due to rain and the associated caking leading to subsequent mineral refusal by cows.
Feeding tubs are an additional alternate form of supplementation producers have found to improve resistance to weather-related losses.
In mineral tubs, the mineral ingredients are baked within molasses to a hard, taffy-like consistency and poured into a tub during the manufacturing process.
“Producers find that this form of mineral supplementation provides the ultimate in resistance to weather-related losses,” says N.T. Cosby, Ph.D., senior consulting nutritionist for Land O’Lakes Purina Feed, adding that the form of mineral supplementation is consistent and convenient.
Whichever method of protein and mineral supplementation is selected, it is vital to promote palatability through all seasons.
When cows are supplemented with the proper minerals and nutrients, other performance goals can be focused on and the herd can excel on pasture.
PHOTO
Producers should evaluate protein and energy nutrient levels in their pasture before using supplements. Photo courtesy of Land O’Lakes Purina Feed.
Marketing Beef Nutritionist
Land O’Lakes Purina Feed, LLC
