Growing Cattle on Pasture

Published on Mon, 03/29/2010 - 12:38pm

Growing stocker cattle on pasture is an intermediate growing phase within the beef production system. Steers or heifers (stockers) grazed on pasture are generally a low cost way of growing light-weight cattle, 300 to 500 pounds, into feeder cattle weighing 750 to 800 pounds. Profitable stocker production requires that the producer understands the factors that impact efficient, low-cost weight gain. The three main factors that determine profitability are: price received when selling the cattle, cost of cattle, and cost of gain. For brevity’s sake we’ll focus on the cost of gain.



Cost of gain, unlike the other factors effecting profitability, is within our control if we understand the conditions that impact rate of gain and what it means for our bottom line. Average daily gain (ADG) is important because nutritional requirements for growing steers and heifers change based on the rate of gain. There are low cost ways to increase rate of gain profitably if we understand the factors that impact the nutrient requirements of the animals. There are three main factors that determine the nutrient requirements of growing cattle:
1. Current body weight
2. Biological type (small, medium or large frame)
3. Desired rate of gain
Body weight impacts nutrient requirements through the need to maintain body tissue—the animal’s maintenance requirement. The more body tissue (weight) there is to support the higher the maintenance requirement. Before cattle can gain weight they must consume enough energy (forage) to meet their maintenance requirement. Whatever they consume beyond that point can go towards gain.
Biological type—often referred to as frame size—is really an indication of the growth pattern or curve of the animal, which is growth rate over time and mature size/ growth cessation. Small framed steers can grow at the same rate as large framed steers, but for a shorter period of time because they mature earlier. As animals approach maturity the composition of their gain moves from lean tissue (muscle) to fat. Fat deposition requires more energy than muscle, so conversion of nutrients (amount of forage to produce a pound of gain) increases and results in less efficient gain. Smaller framed cattle should start grazing at lighter weights than one might start larger framed cattle because they will begin to fatten at a lighter weight.
We Like Them Lean
The fact that fat cattle don’t gain rapidly on pasture is well known to producers in the business of growing cattle. Consequently the market discounts fat or “fleshy” cattle and favors lean or “thin” cattle because they tend to gain more and at higher rates, particularly during the first half of the grazing period. Termed compensatory gain, the Nutritional Research Council, Nutrient Requirements of Beef Cattle 2000 considers this in assessing nutrient requirements because thin cattle, those with little body fat, gain at a faster rate than fat cattle of the same weight or biological type when on the same diet. Research indicates that compensatory gain on grass is highly variable and challenging to predict, and although compensating cattle might be more efficient in converting nutrients to tissue, much of their additional gain results from higher intake (Klopfenstein, 1999).
This phenomenon is related to biological type in one regard. Two weaned steers of the same weight but different fatness, one very thin and the other very fat, are of two different biological types. In this instance the thinner steer is of the larger biological type and will gain at a higher rate than the smaller, fatter one on the same diet. The visual difference between these two animals is obvious. The thinner calf will have a larger skeletal structure than the fatter calf. The reason the thinner calf will gain faster is that the composition of his gain early in the growing period contains more muscle and less fat. Because fat deposition requires more energy than muscle the thin calf gains faster when fed the same diet as the fatter calf. It’s all about the efficiency of energy conversion. Faster gain and more efficient conversion of nutrients to body weight combined create a powerful profit driver for cattle growers. So what kinds of cattle do cattle growers prefer? No question about it, thin ones. That preference is why prices for thin cattle are higher than fleshy ones of the same weight and quality. Chances are the thinner cattle, providing they’re healthy, will exhibit some degree of compensatory gain. When we understand the effects of compensatory gain and conditions that create it we can leverage it to a profitable advantage when growing cattle on pasture.
Top Them Off
The last step in maximizing profit from our stocker enterprise is in understanding how to extract more energy from the forage that results in weight gain. Increasing intake will result in more gain, but the cattle are already eating to their capacity. The objective is to improve the conversion of the forage they’re already eating. We do that by providing the nutrients that are deficient in the forage that are limiting gain.
Late in the grazing season when the forage is declining in protein a low-intake protein supplement can economically improve gain. In a Kansas State study, of stockers grazing Flint Hills pasture (Barnhardt, et. al., 2006 Cattleman’s Day Report), cattle supplemented one pound per day of a protein-mineral supplement during the last half of the grazing season gained an additional 0.5 pounds per day over the forty-five days supplemented. That’s a 2 to 1 conversion on the supplement. The half pound gain was worth $0.45 ($0.90/lb.) and it cost us less than $0.20 to put it on. That’s a real efficiency improvement, both biological and economic. Net profit increase for the supplemented steers over the non-supplemented was $5.63/head.
The even bigger win is using a high quality stocker mineral with the correct growth additive for the situation; monensin, lasalosid or chlortetracycline. One of these additives with a high quality mineral yields an additional 0.25 to 0.3 pounds ADG, over a 100-day grazing period that’s twenty-five to thirty pounds. If our selling price for the cattle is $0.90 after shrink and commissions the additional revenue is $22.50 to $27.00 per head. The mineral cost is approximate $10 per head; add $2 per head to put it out and it’s a $10 to $15 per head profit. Quality stocker mineral with an additive is the best investment in the cattle business.
The Bottom Line
It’s true that when growing cattle on  pasture there are elements beyond our control, but cost of gain shouldn’t be considered one of them. If you’re not taking advantage of and managing these concepts you’re leaving money in the pasture.
Bryan McMurry, with Cargill Animal Nutrition, earned his Masters Degree in Animal Breeding and Genetics, and a PhD in Animal Science from Texas A&M University.
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