Source: University of Minnesota Extension, Pete Anderson, former Extension beef cattle specialist
Quick facts
- Starting weight and age greatly affect feed intakes.
- Large-framed cattle have more efficient gains because they are less mature than small-framed cattle at equal weight or age.
- Strive to produce carcasses with 2 square inches of ribeye area per 100 pounds of carcass weight.
- Weight accounts for 88 percent of the differences in feed intake within a given breed, but only 14 to 33 percent between breeds.
- Implants can improve cattle performance.
Predicting breakeven prices is key to profit in cattle feeding. You must predict feedlot performance correctly to compute breakevens. The following vary greatly from one group of cattle to another:
- Average daily feed intake (ADFI)
- Average daily gain (ADG)
- Feed conversion (F/G)
- Days on feed
- Carcass traits
- Disease and death rates
Knowing how the following factors affect feedlot performance can help you match cattle type and feedlot performance.
Starting age or weight
Age and starting weight have great, expected effects on cattle dry matter intake. Feed intake tends to be the only performance trait feedyards measure often. Feed intake relates to gain and efficiency (table 1). Feeders try to obtain maximum, steady feed intake.
Many predict feed intake using a graph that shows as cattle get heavier, feed intake increases but intake as a percent of body weight decreases. They don’t always consider age. It’s hard to tell age effects from weight effects but they aren’t the same.
Oklahoma State University looked at records from a large commercial feedlot in Oklahoma. Cattle show have an expected pattern of feed intake that closely relates to their starting weight. Overall, feed intake quickly increased for all groups of cattle when they first adapted to the feed. Intakes then increased slowly or stayed the same as weights increased until the end of the feeding period when intake declined.
A like pattern occurred in all cattle, despite their starting weights. But intakes were higher at all points for heavier cattle when placed on feed. This suggests that predicting ADG from estimated feed intakes that don’t consider start weight, may overestimate performance of heavy cattle.
Calf and yearling feed intake differs across the same number of days on feed. The difference in weight between calves and yearlings doesn’t fully explain the differences in feed intake.
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Yearling cattle feed intake steadily increases for the first 40 to 50 days on feed, plateaus for 40 days and then declines until slaughter.
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Calf feed intake slowly increases for about 70 days and then plateaus.
Frame size
Growth
The general shape of the growth curve doesn’t differ between frame size and age and weight. But cattle with the same age and weight will be at different points on the curve if they differ in frame size. Separate from breed effects, increase frame size results in:
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- creased growth rate
- Increased time required to reach choice quality
- Decreased fat thickness and marbling at equal weight
- Increased weight at equal fat thickness
Large-framed cattle have more efficient gains because they are less mature than small-framed cattle at equal weight or age. Large-framed cattle gain more muscle and less fat than small-frame cattle. But when fed to equal carcass makeup, large- and small-framed cattle are usually alike in efficiency.
Table 2 shows how frame size affects growth rate and profit as reported by Kansas State University. Rate of gain increases with frame size but profit shows little change after yearling height reaches 47 inches. In this study, cattle with the most profit were those that grew quickly and reached choice quality grade.
Table 2. Gain, carcass traits and net return of Kansas futurity steers by frame size.
Selection
Feeders should strive to get cattle from herds selected for performance. Frame size can help predict the weight at which cattle will grade choice, but is only a minor predictor of performance.
Michigan State University fed two groups of cattle with similar frame scores. One group was an unselected line and one group was a line selected heavily for growth, but not frame size. Over a 221-day feeding period, the selected cattle out-gained the unselected cattle 3.1 to 2.4 pounds per day. Thus selected cattle produced 155 more pounds of gain per head with alike frame size.
Dietary energy
Prior et al. 1977 fed low, medium and high energy diets to small-framed and large-framed cattle during feeding periods of various lengths. Low energy diets aren’t practical for an entire feeding period.
Increasing diet energy had the following effects:
- Increased ADG in both cattle types
- Improved feed conversion in both cattle types
- Increased all measures of fatness in small-framed, but not large-framed cattle.
- Promoted weight gain in both cattle types
- Small-framed cattle gained weight in fat
- Large-framed cattle gained weight in muscle
In this study, small-framed and large-framed cattle were slaughtered at an average yield grade of 4.2 and 3.0, respectively. The authors estimated that dietary energy needed to deposit a pound of lean was the same across diet treatments and frame sizes.
Muscling
Light muscled carcasses may result in deep discounts. Strive to produce carcasses with 2 square inches of ribeye area per 100 pounds of carcass weight. Carcasses with less than 1.6 square inches will receive severe penalties. Even carcasses less than 1.8 square inches may receive discounts.
Crossbreeding systems and within-breed bull and female selection resulted in an industry average of 1.8 square inches.
Performance and cutout
Colorado State University studied differences in performance and cutout between cattle of different muscling. They fed feeder calves to slaughter. These calves included each of the feeder calf muscle scores (1 to 3, 1 is most muscled) and frame sizes (small, medium and large).
Frame size had expected effects on performance and slaughter weight. But muscling didn’t affect feedlot growth rate, even though muscled calves were much heavier entering the feedlot.
Change in live weight poorly describes performance of cattle that differ in muscling. In this study, muscled cattle had higher dressing percents and greater muscle yield, despite no difference in growth rate or live weight. Thus the rate of muscle weight gain was greater in muscular cattle.
If carcass or live cattle pricing becomes based on muscle or lean content of the carcass, rather than weight, muscled cattle will have an advantage. Widespread use of hot fat trimming would enhance the value of muscular carcasses.
Breed
Weight
Taylor et al. 1986 compared cattle of 25 different beef and dairy breeds. They found that weight accounts for 88 percent of the differences in feed intake within a given breed, but only 14 to 33 percent between breeds.
For young, growing cattle, feed intake within a breed wasn’t proportionate to body weight. Thus, cattle groups of the same breed will have alike feed intakes, which you can predict by weight. Cattle of another breed may be quite different, even at the same weight.
These researchers further found that genetically larger breeds ate relatively more feed at young ages. This may partly explain the effect of start weight on feed intake since cattle with higher start weights were likely more of the larger breeds. Pamp’s 1981 data supports this. Pamp saw low, insignificant links between start weight and rate of gain within breed comparisons of data from University of Minnesota studies.
Maintenance needs
Cows
Ferrell and Jenkins 1984 found that the energy required to maintain a cow’s weight differs up to 30 percent between breeds. This also holds true when the cows aren’t growing, pregnant or lactating.
Work in cows shows that maintenance needs (per unit of weight) highly relates to potential milk production, even when cows are dry. This results from vital organs having a larger mass and higher energy need in high milk breeds.
Steers
It’s likely maintenance needs between breeds differs in steers.
Liver size relates to within-breed performance of growing steers and likely differs between breeds as well. If so, steers of two breeds that eat similar amounts of feed could differ in ADG and F/G due to differing maintenance needs. A 15 percent difference in maintenance needs between two breed types results in about a 9 percent difference in feed needed for alike ADG. Also, differences in gain composition may cause differences in gain efficiency, with no difference in rate of weight gain.
Dairy breed steers are thought to have maintenance needs about 12 percent greater than beef breed steers. Steers from higher milking beef breeds probably have higher maintenance needs as well. You can manage dairy breed steers to gain as much, or slightly less than beef breed steers. But they will eat about 8 percent more feed, and thus convert feed less efficiently than beef breed steers.
Sex
Feedlot cattle consist four sex groups: bulls, steers, heifers and ovariectomized heifers. You can implant each of these groups with androgenic or estrogenic hormones. Implanted steers and heifers makeup the most of all feedlot cattle.
At equal carcass quality, heifers weigh 20 percent less than their steer mates. But since heifers mature earlier, they reach a given endpoint sooner than steers. Thus the difference in feedlot ADG is less than 20 percent, most estimates range from 8 to 15 percent. These differences are similar when both groups have implants. Bulls would likely weigh 10 to 15 percent more than implanted steers at similar composition.
Comparing bulls to steers
Anderson et al. 1988 compared bulls to steers slaughtered at the same age as bulls (Steers I) or at the same slaughter weight as the bulls (Steers II). As expected, performance of the bulls was superior to both groups of steers, even though steers had excellent performance.
Daily carcass fat gain of bulls (0.96 pounds) was similar to Steers I (1.04 pounds) and Steers II (1.03 pounds). Thus, carcass leanness of the bulls is from greater lean gain per day than less fat gain. Steers have higher quality grades than bulls. Most of the performance advantages are reduced if bulls are fed until they grade choice. But there are many reports, which show that bulls under 16 months old and fed a high energy diet for at least 150 days, produce highly palatable beef, despite low quality grades.
There are many reasons why few bulls are fed for beef in the United States but bull beef may have a future.
Growth-promoting implants
Always consider implant effects when projecting performance.
Steers implanted with estrogen(E)-containing products will likely:
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Gain 8 to 10 percent faster
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Eat more feed
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Convert feed more efficiently
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Be leaner at any weight endpoint
Heifers respond to implants designed for females, but respond less than steers.
Trenbolone acetate (TBA) with estrogen
Trenbolone acetate (TBA), a synthetic androgen, enhances performance alike, or slightly less than estrogen-containing implants. But TBA used with estrogen-containing (TBA+E) implants is a strong growth stimulator. TBA+E increased gains by 15 to 30 percent in most trials with an average increase of 20 percent. Trials showed a similar increase in feed conversion.
Because of its great muscle-enhancing effects (ribeye area often increases 1 to 2 square inches), some cattle feeders have seen poorer quality grades in cattle with TBA+E implants. It’s unknown if TBA+E reduces marbling or if the cattle need to get marketed at heavier weights than if they had only E-containing implants.
Many researchers believe that cattle implanted with TBA+E will grade well, if fed to 75 or 100 pounds heavier weight than if not implanted. You must consider the added performance and increased slaughter weight requirement when projecting performance and slaughter weights of cattle with TBA+E implants.
Condition or prior nutrition
Cattle feeders can profit from buying thin feeder cattle and taking advantage of compensatory gain. Table 3 shows data from a Kansas survey of prices paid for feeder calves based on condition at purchase. It’s clear that buyers don’t favor fat calves at the time of sale.
Most reports show that cattle subject to restricted dietary energy, which may occur in a pasture or backgrounding system, will compensate when fed high energy diets. Usually, this compensation will include the following for periods of up to 42 days:
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Increased feed intake (5 to 10 percent)
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Increased ADG (10 to 30 percent)
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Improved feed conversion (15 to 40 percent)
Projecting performance greatly differs for cattle with likely compensatory growth and noncompensating cattle. As condition increases, energy needed for maintenance rises and the energy for gain declines. You can adjust diet energy or project gains of feedlot cattle based on condition at the start of the feeding period (table 4).
Ridenour et al. 1982 suggests caution buying calves for compensatory gain. In this study, cattle fed 50 percent concentrate diets or grazed on irrigated wheat pasture until they
reached 550 pounds, had normal compensatory responses when placed on full feed. But cattle that received either of these treatments until 800 pounds compensated very little. The cause is unclear but it may be that as cattle age or gain weight their ability to compensate declines.
Table 4. Adjustment factors for feedlot nutrient needs based on condition entering the feedlot.
Prior care
The following care practices greatly stress calves:
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Weaning
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Castrating
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Dehorning
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Vaccinating
Research at Iowa State University has examined the effects of timing of these practices, together or separately, on feedlot performance (Table 5).
Environment
The following weather elements can affect beef cattle performance in the Upper Midwest.
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Cold
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Wind
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Snow
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Rain
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Heat
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Humidity
You can’t predict weather but using adjustment factors will help you adjust projections based on observed weather.
Bourdon et al. 1984 reported that maintenance needs increase over 24 percent during cold stress and adjusting to the environment in commercial Colorado feedlot cattle. An increase of 37 percent occurred during November, December and January. Gains declined about 1/2 pound daily, with little change in intake. As a result feed needed per unit of gain increased about 1 unit. If cattle are acclimated, cold weather can increase intake, to meet the greater resting metabolism needs.
Plegge 1987 reported that intakes of 14,199 cattle averaged 8 percent higher in winter months than summer months in Minnesota. Hicks et al. 1990b found that ADFI peaks in late fall, May and June. The lowest intake occurred in late winter, July and August.
Muddy pens also affect performance. Bond et al. 1970 saw 25 to 37 percent declines in daily gain and 20 to 33 percent declines in efficiency from muddy feedlot pens. Rayburn and Fox 1990 developed prediction equations based on 15 years of Holstein steer data in Minnesota, Wisconsin and New York. Table 6 contains descriptions of the effects of mud on performance.
Sources
Anderson et al. 1988. Anim. Prod. 47:493.
Bourdon. 1984. Colorado St. Univ. Beef Report
Ferrell and Jenkins. 1984. J. Anim. Sci. 58:234.
Fox et al. 1988. J. Anim. Sci. 66:1475.
Hicks et al. 1990a. J. Anim. Sci. 68:245.
Hicks et al. 1990b. J. Anim. Sci. 68:254.
Lambert. 1984. J. Anim. Sci. 59(1):89.
Pamp. 1981. Ph.D. Thesis, University of Minnesota.
Peterson et al. 1989. J. Anim. Sci. 67:1678.
Plegge. 1987. Proc. Int. Feed Intake Symp., Okla. St. Univ.
Prior et al. 1977. J. Anim. Sci. 45:132
Rayburn and Fox. 1990. J. Anim. Sci. 68:788
Ridenour et al. 1982. J. Anim. Sci. 54:1115.
Tatum et al. 1988. J. Anim. Sci. 66:1942
Taylor et al. 1986. Anim. Prod. 42:11.
