Supplementation of stocker cattle grazing bermudagrass, an inherently moderate- to low-nutritive value forage, has often been used by managers to increase animal performance.
Supplementation of stocker cattle grazing bermudagrass, an inherently moderate- to low-nutritive value forage, has often been used by managers to increase animal performance.Management strategies to incorporate some level of supplementation for stocker cattle include some or most of the following objectives:
- Increase average daily gain (ADG)
- Increase stocking rate and overall gain per acre
- Create niche performance attributes (i.e., replacement heifers)
- Provide a “buffer” or alternative to overstocked pasture conditions and insufficient available forage for desired weight gain
Thus, managers have used supplemental feed sources based on their perceptions of a positive outcome, efficiency of performance attributes or as a “Band-Aid” and “salvage operation” to prevent the necessity of premature livestock sales.
Once management has interest in the use of a supplement, they are faced with many predictable questions. What do I feed? How much do I feed? How often do I feed?
How do I deliver the supplement (i.e., self-limiting or hand-fed)? Regardless of the answers to these or other questions, managers should focus on seeking comparative information on the biological and economic efficiency of using a supplement.
Comparative information results from replicated supplementation experiments that include non-supplemented “controls” and statistical analyses of the data collected. The questions to ask should be directed toward “What is the supplement-to-extra gain ratio?”
There are expectations and perceptions of added gain with supplementation. However, operators want to know what amount of daily supplement results in the most economically beneficial rate for the stocker venture.
Research scientists usually express amount of daily supplement as a percent of animal bodyweight (BW). For example, many of the early experiments used daily supplement rates of 1 percent BW. In almost all cases, this rate of supplementation showed increased gains.
But at what cost did this gain come? Stocker cattle have an estimated daily level of intake of about 2.2 to 2.8 percent BW, and gain is affected by quantity and quality of available forage. Thus, at 1 percent BW, supplemental feed approximates nearly half of the daily intake of the stocker. What costs more, the pasture or the supplement?
The research for ADG
A two-year supplementation of stocker steers on Tifton 85 bermudagrass using different daily rates of dried distillers grains with solubles (DDGS) was conducted at the Texas A&M AgriLife Research & Extension Center at Overton. The DDGS are byproducts of corn-based ethanol production. In the past, DDGS have been used primarily in feedlot rations.
Although DDGS have been used as a supplement with dormant forage or hay, little research has been conducted to assess the impact of DDGS as a supplement for stocker cattle grazing warm-season perennial grasses such as bermudagrass.
At Overton, steers were hand-fed daily four rates of DDGS according to BW (0 percent, 0.25 percent, 0.5 percent and 1 percent BW). The two-year ADG ranged from 1.85, 2.46, 2.57 and 2.88 pounds per day, respectively, for the four rates of DDGS (Table 1).
An analysis of these ADG showed that all levels of DDGS increased gains compared to non-supplemented stockers, and the 1 percent BW rate resulted in the highest ADG.
A closer evaluation of the biological and economic efficiencies showed that the amount of DDGS required to produce an extra pound of gain (DDGS-to-extra gain, pound per pound) was 3.7 to 1 for 0.25 percent BW, 6 to 1 for 0.5 percent BW and 9 to 1 for 1 percent BW supplementation.
These conversions of DDGS-to-extra gain ratios showed the 0.25 percent BW rate to be the most biologically efficient, acting in an “additive” or “associative” manner. The 1 percent BW rate, however, was acting in a “substitution” role. Since the total daily dry matter intake of these stockers likely did not exceed 2.5 percent BW, the 1 percent DDGS level was actually “substituting” or replacing nearly half of their daily intake of forage dry matter.
What the gain costs
As a more memorable impact for stocker operators, the feed cost of DDGS for an additional pound of gain was 40 cents for 0.25 percent, 65 cents for 0.5 percent and 90 cents for 1 percent BW (Table 1).
Since the rates of supplement increased ADG and also served in a “substitution” role at the higher levels of DDGS, live weight gain per acre was increased with increasing DDGS supplement offered. At the 1 percent BW rate, gain per acre at 1,661 pounds per acre was more than twice that of the non-supplemented stockers at 756 pounds per acre.
From the perspective of fertilizer inputs, cost per pound of gain at the 1 percent BW DDGS rate was 9 cents versus a 19-cent cost per pound of gain for the non-supplemented cattle. Therefore, the management strategy to remember is that, for pastures such as Tifton 85 bermudagrass that are highly responsive to fertilization, the costs per pound of gain for fertilizer are very minimal compared to the costs per pound of extra gain for supplementation.
Although the use of DDGS resulted in positive stocker gains, this study did not compare the effect of an energy-based supplement, such as corn.
The most challenging aspect of any supplementation strategy is the method of delivery. The physical form of DDGS used in our study was granular; thus, bunk space was required that would not have been a consideration had the feed been offered on the ground.
In addition, unless an intake restriction additive (such as salt) is included, hand-feeding is necessary to control the level of desired daily intake.
Once the delivery system has been solved, the most biologically effective rate of supplementation will approximate the 0.25 percent BW. However, cost of supplement, delivery system, price of cattle, available forage in the pasture, and overall gains per animal and per acre controls the final supplementation strategies for management. 
PHOTO: When stocker cattle graze low-energy bermudagrass, supplements can improve average daily gain; however, rate of inclusion can determine whether the supplement acts as an additive or a substitution. Photo by Brandon Smith.
Monte Rouquette Jr. is a Regents professor with Texas A&M AgriLife Research at Overton, Texas.
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W. Brandon Smith
- Ph.D. Graduate Assistant
- Texas A&M AgriLife Research and Texas A&M University
