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Ration Formulation for Growing Cattle

Ration Formulation for Growing Cattle

By Nathan G. Briggs and Tara L. Felix

Formulating a diet for beef cattle and feeding a balanced ration are keys to having a successful beef operation. However, diet formulation does not always seem straightforward. There are numerous feed ingredients possible for cattle diets and numerous ways to combine those feed ingredients to meet beef cattle daily requirements. Most beef cattle nutritionists and producers begin balancing a ration using a least-cost formulation that considers the overall cost of mixing the diet and feeding the daily ration. Proper ration formulation for animal class allows nutritionists to predict how long beef cattle will need to be fed to achieve a targeted body weight. Before a diet can be formulated and a ration developed for gain predictions, the following things need to be known:

  • Animal type
  • Animal sex
  • Animal weight
  • Available feed ingredients
  • Use of feed technologies
  • Housing type

These categories are important because each one impacts the nutrients required for maintenance and gain of beef cattle. There are truly only six classes of nutrients for any animal (or human): water, carbohydrates, protein, fat, vitamins, and minerals. However, these nutrients are used by cattle for growth and development. For example, carbohydrates and fats are digested to provide energy to the animal. The terminology most commonly used to discuss beef cattle requirements is often based on broader classifications of these nutrients that explain their function in the animals: net energy for maintenance (NEm), net energy for gain (NEg), total digestible nutrients (TDN), neutral detergent fiber (NDF), crude protein (CP), fat, minerals, and vitamins. These terms group the six classes of nutrients more by their respective functions. For example, carbohydrates, fat, and protein may all contribute to the NEm and NEg.

While there are books written to define these categories and tables to ascertain requirements at each stage of production, there are also some general guidelines that can be used for growing beef cattle. As always, it is recommended that you use the following information as guidelines only and consult with a beef cattle nutritionist to determine the best diet for your operation.

In many diets for growing cattle, CP ranges between 11 and 16 percent, NEm ranges between 78 and 91 Mcal per cwt (where cwt is equal to 100 pounds), and NEg ranges between 50 and 61 Mcal per cwt. In most grain-based diets, however, the NEg will not drop much below 54 Mcal per cwt. Feeding diets with less than 54 Mcal per cwt would be more typical in a forage-based management program. The fat content of a beef cattle diet should not exceed 6 to 7 percent of the diet. And, while minerals and vitamins are often fed as a commercial premix that is added at a specified amount to the daily ration, it is important to point out that the ratio of calcium to phosphorus (Ca:P) should be 2:1 in the total diet. Repercussions of not meeting these requirements will be poor growth, impaired health, and insufficient nutrient utilization.

Given the consequences of not meeting requirements, one might question the seemingly broad range for the "rules of thumb" provided. Typically, diets fed to growing beef cattle will step up, or increase, in energy over the course of the feeding period. This stepwise increase allows the calf’s rumen to adjust to changes in the diet, primarily increasing concentrations of grain necessary to increase energy density. For example, a 400-pound calf may start in the feedlot consuming a diet of 56 Mcal of NEg per cwt. This diet would likely contain 40 percent corn grain (dry matter basis) or less. The calf would then transition to a diet of 58 or 59 Mcal of NEg per cwt after a week to 10 days and then to a diet 60 to 62 Mcal of NEg per cwt after another week to 10 days. This calf would then remain on, or "finish on," 60 to 62 Mcal of NEg per cwt until slaughter, but its daily intake, or ration, would likely increase as time went on. In addition, this stepwise increase allows nutritionists and producers to adjust the concentrations of protein in the diet to achieve the desired grams of protein consumption per day. Because lighter cattle cannot physically eat as much feed, the diet fed to them must have a greater concentration of protein in order to achieve a similar grams-per-day intake of protein. The difference between concentration and consumption is evidenced in the examples discussed later in this article.

Thus, the ingredients and their proportion may differ to meet those varying crude protein and NEg requirements based on animal intake. Along these lines, we know though that the amount of fiber in the diet will affect how much of the diet that growing calf will be able to consume. Beef cattle intakes can range from 2 to 3.5 percent of body weight (BW) on a dry matter (DM) basis, with young calves consuming more than older cattle. Feeding predominantly fiber, or a forage-based diet, will limit cattle intakes closer to 2 percent of their BW. With less fiber in the diet, lightweight cattle (cattle under 600 pounds) can consume up to 3.5 or even 4 percent of their BW. Intake, as a percent of BW, will decrease as cattle grow. Thus, once cattle weigh between 700 to 800 pounds, intake will be closer to 2 percent of BW. The transitions become critical because sick animals—cattle with either respiratory issues or digestive upsets—will consume only 1 percent or less of their BW (DM basis). In the instance of sickness, energy will be reallocated toward the immune system rather than performance and growth will be retarded.

One of the categories previously mentioned was animal type. Both sex and breed will impact the nutrient requirements for cattle. Heifers, for example, will fatten more quickly than steers, and an Angus calf will grow differently than a Charolais on a similar ration. Dairy breeds and crosses typically require "hotter" rations, or a ration with more NEg, when compared to beef breeds. Cattle type is just one of the many categories that must be considered when feeding growing cattle.

Nutritionist and cattle producers must consider first and foremost, after what they are feeding, how they are feeding those animals. Growing and finishing diets for cattle are limited only by the imagination. If a feed or byproduct is readily available at a competitive price, then that feed should be used in the diet formulation. To attempt to ensure a profit, the price for each feed should be considered when formulating a diet. While nutritionists and producers are encouraged to investigate low-cost feed options in their regions, the most common on-farm feed ingredients—corn, unroasted or raw soybeans, corn silage, orchardgrass hay, limestone, and vitamin/mineral premix—are used in the example diets contained in this publication. Unroasted or raw soybeans are a good, cheap source of protein. Unlike nonruminant species, cattle do not need soybeans to be roasted to grow efficiently. Antinutritional factors that negatively affect nonruminant species are less of an issue in ruminants; therefore, cattle feeders that grow their own beans can save the processing costs by including them in the diet.

Using technologies available  for growing beef cattle can improve the feed-to-gain conversion, the bottom line for most growing and finishing cattle operations. For example, using steroidal implants will improve cattle average daily gains, increasing both live cattle weight and hot carcass weight at the same number of days on feed. While economics can obviously vary from year to year, most implant strategies net a return of $50 to $100 per animal.

One of the most common feed technologies available to beef cattle producers are ionophores  , a class of nonmedically relevant antibiotics. Ionophores will improve feed efficiency in beef cattle fed grain by decreasing the amount of feed intake without altering average daily gain. Ionophores achieve these results by selectively targeting less efficient bacteria, which waste energy from the ration, and decreasing their numbers in the rumen. This selection decreases acetate production and, ultimately, wasted energy products like carbon dioxide and methane, and allows bacteria that produce propionate to flourish. Ultimately, this bacterial shift allows the cattle fed ionophores to retain more energy from their feed. In the United States, over 90 percent of the cattle on feed are fed ionophores. The net return on investment for cattle producers feeding ionophores is around $20 per animal.

Melengestrol acetate (MGA) is a common feed technology for feedlot heifers that has been used since 1968 to suppress estrus, improve average daily gains, and increase feed efficiency. On average, feeding heifers MGA increases live weight by 25 pounds, hot carcass weights by 19 pounds, and average daily gain by 0.15 pound compared to those heifers that are not fed MGA. In addition, heifers fed MGA have a better potential for grading choice/prime, reduced incidence of dark cutters, and a shift toward increased yield grade when compared to heifers that are not fed MGA. However, this technology is only relevant for operations that feed steers and heifers in separate pens because MGA is only FDA approved for feeding heifers. Feeding a mixed pen of heifers and steers MGA would be unlawful, and those steers would not be permitted to enter the food chain by law.

Another technology available to beef cattle producers are beta-adrenergic agonists, commonly referred to as beta-agonists. Beta-agonists function by shifting fat deposition to muscle deposition during the final days of finishing; thus, they can only be added to a ration during the last 28 to 42 days of the feeding period. Ractopamine hydrochloride is a beta-agonists marketed as Optaflexx® that increases average daily gain by 15 to 25 percent without increasing feed intake. On average, producers will see an average return on investment of $20 per animal when feeding beta-agonists. Managing the feeding of beta-agonists can be the biggest challenge for cattle producers that sell cattle weekly or biweekly from a group pen because of the feeding restrictions. As a result, beta-agonists work best for producers that can target delivery to a set pen for the designated 28 to 42 days.

Housing type must also be factored into our feeding decisions because housing cattle in a manner that permits wet, matted haircoats increases nutrient requirements compared to cattle that are kept dry. In the winter, keeping animals out of the wind and dry can help ensure the most efficient use of nutrients.

With all of these factors in mind, sample diets have been prepared for three different management scenarios with result economic analyses (Tables 1 and 2).

Table 1. Rations for growing and finishing steers at 600 to 800 pounds.

IngredientDiet 1Diet 2Diet 3Diet 4
As-fed inclusion    
Corn (pounds/head)9.2711.816.689.82
Soybeans (pounds/head)1.361.892.262.26
Corn silage (pounds/head)16.008.00
Orchardgrass hay (pounds/head)4.591.53
Limestone (pounds/head)0.140.210.180.21
Vitamin and mineral (pounds/head)0.250.250.250.25
     
Daily intake (pounds as fed)15.615.725.320.5
Total digestible nutrients (percent DM basis)76.182.079.282.1
Crude protein (percent DM basis)12.8412.9012.8913.02
Net energy for gain (Mcal/cwt)54.5962.3660.4363.35
Calcium-to-phosphorus ratio1.751.861.811.85
     
DM of the diet (percent)89.889.367.978.5
Average daily intake (pounds DM/head)14141414
Intake as a percentage of body weight2.02.02.02.0

Table 2. Rations for growing and finishing steers at 800 to 1,400 pounds.

IngredientDiet 1Diet 2Diet 3Diet 4
As-fed inclusion    
Corn (pounds/head)16.3420.2112.1517.21
Soybeans (pounds/head)0.591.542.132.01
Corn silage (pounds/head)25.1412.57
Orchardgrass hay (pounds/head)7.222.41
Limestone (pounds/head)0.220.330.280.33
Vitamin and mineral (pounds/head)0.250.250.250.25
     
Daily intake (pounds as fed)24.624.740.032.4
Total digestible nutrient (percent DM basis)76.482.477.881.6
Crude protein (percent DM basis)10.8811.0811.0711.05
Net energy for gain (Mcal/cwt)54.8062.5860.6563.56
Calcium-to-phosphorus ratio1.811.911.861.92
     
DM of the diet (percent)89.489.067.578.1
Average daily intake (pounds DM/head)22222222
Intake as a percent of body weight2.02.02.02.0

Diet 1

Diet 1 has been formulated to meet the requirements for starting 600-pound Angus-based steers and feeding until finish weight. Diet 1 is an attempt to depict a free-choice hay scenario with separate grain feeding. However, free-choice hay feeding scenarios are difficult to model due to fluctuations in individual cattle intakes of both hay and grain. Therefore, diet 1 includes hay at 30 percent of total DM because research suggests that cattle given free access to hay will consume close to 30 percent of their daily DM as hay. Other feeds in this diet include corn, unroasted or raw soybeans, limestone, and a commercial vitamin/mineral premix. Growth predictions have been made based on the assumption that no feed technologies are being used. If feed technologies such as ionophores, beta agonists, or implants are used in combination with these diets, increased weight gain and profitability would be realized. Adequate pen and bunk spacing requirements were assumed (FASS 2010). If cattle are overcrowded or do not have enough space, then increased competition at the bunk can reduce intake while increasing the risk of illness in the pen.

Diet 2

Diet 2 has been formulated to meet the requirements for starting 600-pound Angus-based steers and feeding until finish weight. Like diet 1, this diet utilizes hay, corn, unroasted soybeans, limestone, and a commercial vitamin/mineral premix; however, unlike the first diet, this diet limits hay to 10 percent of the DM inclusion to limit hay intake in an effort to increase average daily gain and feed efficiency. Growth predictions have been made based on the assumption that no feed technologies are being used. Adequate pen and bunk spacing requirements were assumed (FASS 2010).

Diet 3

Diet 3 has been formulated to meet the requirements for starting 600-pound Angus-based steers and feeding until finish weight. This diet assumes feeding corn silage at 40 percent (DM basis) of the diet along with corn, unroasted soybeans, limestone, and a commercial vitamin and mineral mix. Growth predictions have been made based on the assumption that no feed technologies are being used. Adequate pen and bunk spacing requirements were assumed (FASS 2010).

Diet 4

Similar to the previous scenarios, diet 4 has been formulated to meet the requirements for starting 600-pound Angus-based steers and feeding until finish weight. This diet also utilizes home-raised corn silage, like diet 3. However, in diet 4, corn silage is included at only 20 percent of the diet (DM basis) to demonstrate the growth performance and economic differences realized when fed "hotter" diets. Growth predictions have been made based on the assumption that no feed technologies are being used. Adequate pen and bunk spacing requirements were assumed (FASS 2010).

Growth Performance Predictions and Economic Analyses

Feeding programs are split into two stages to better estimate economics. The first stage targets growing steers from 600 to 800 pounds that will consume less feed on a daily basis. These cattle will require a greater proportion of protein in the diet simply because they are eating less. The second stage will focus on cattle from 800 to 1,400 pounds, which will consume more because of their size, and thus the percentage of crude protein in the diet does not need to be as much as that fed in the first stage. Managing for the different stages of intake allows us to adjust the daily ration as needed to deliver the nutrients the cattle require. Table 1 details the expected rations for growing cattle from 600 to 800 pounds, and Table 2 details the finishing rations for all four diets fed to cattle from 800 to 1,400 pounds. The estimated diet nutrient composition, expected feed intake, and expected daily gain are listed in each table. Intake was calculated based on 2 percent of body weight. Growth performance predictions for the entire feeding period and the corresponding economic outcomes were determined for each of the four aforementioned diets (Tables 3 and 4). Market volatility was eliminated by using feeder and finished cattle prices from the same week. In a similar fashion, prices were set for feed ingredients with corn at $140 per ton, corn silage at $35 per ton, orchardgrass hay at $140 per ton, unroasted or raw soybeans at $315 per ton, limestone at $238 per ton, and a commercial vitamin/mineral premix at $700 per ton (Table 5). Current pricing schedules should be considered in each region.

Table 3. Performance predictions for growing 600-pound steers to finish at 1,400 pounds.

 Days on FeedTotal Intake (pounds DM basis)Average Gain per Day (pounds)Feed-to-Gain Ratio
Diet 13045,4862.77.22
Diet 22694,8483.06.39
Diet 32785,0102.96.58
Diet 42664,7983.16.31

Table 4. Economic predictions for growing 600-pound steers to finish at 1,400 pounds.

 Feed Cost per Head per DayTotal Cost per Head per DayFeeding Period CostYardage CostPurchase PriceSale RevenueProfit or Loss
Diet 1$1.40$1.90$427.93$152.00$821.16$1,501.08$100.85
Diet 2$1.46$1.96$393.93$134.50$821.16$1,501.08$151.49
Diet 3$0.81$1.31$226.53$139.00$821.16$1,501.08$314.39
Diet 4$1.08$1.58$286.09$133.00$821.16$1,501.08$260.83

These analyses consider only the purchase and sale price of the cattle and feed. No considerations for the risk of purchasing live animals were added to the models. It is important to keep in mind that mortality rates will impact the profitability analysis and typical mortalities in feedlots vary but are generally less than 2 percent.

Table 5. Feed ingredient pricing schedule

Feed IngredientPricing (per as-fed ton)
Corn$140.001
Corn silage$35.002
Orchardgrass hay$140.003
Whole soybeans$315.003
Limestone$238.004
Mineral$700.004

1 Corn prices are a five-year average from USDA NASS plus a $0.50 basis for Pennsylvania.
2 Corn silage pricing is valued at nine times the bushel price of corn grain.
3 Prices based on five-year average from USDA AMS.
4 Southcentral Pennsylvania local mill prices.

Factors impacting mortality and morbidity include housing, management, and immune status of the cattle entering a facility. For this reason, cattle that have been weaned for at least 45 to 60 days and properly vaccinated against common cattle diseases often sell at a premium compared to cattle that are not vaccinated and/or are "weaned on the truck." Sick cattle will consume less but ultimately end up costing the operation more because of their reduced performance compared to healthy pen mates. From a management standpoint, bulls entering the feedlot with advanced testicular development that must be castrated will have added days on feed, due to the added stress from castration, compared to steers entering the feedlot that were castrated at a young age. Talk with your veterinarian about the best method of castration if bulls are being purchased, or consider modifying your own protocols to castrate farm-raised cattle at a young age.

Cattle purchased from reputable buyers will likely meet or exceed predictions made in this article. All economic predictions were made based on selling commercial; profits can be larger than predicted if selling finished cattle directly to consumers or in another niche market. However, those premiums are defined by the seller and therefore were not considered in this analysis.

Yardage cost includes those associated with bedding and daily facility upkeep. Yardage costs will vary from feedlot to feedlot, but for these economic analyses, yardage was assessed at $0.50 per animal each day.

Diet 1 Analysis

The intake of NEg from diet 1 is limited because 30 percent hay is being fed. Greater inclusions of dietary fiber, as with free-choice hay feeding, limit the amount of BW gain per day. In the diet 1 example, hay increases the total ration cost and the days on feed to get the cattle to a finished weight. As cattle age, they convert feed to pounds of gain less efficiently. Thus, as cattle intake starts to plateau, the amount of feed per pound of gain increases. Finishing cattle past 1,400 pounds quickly gets expensive and inefficient. Targeting 1,350 to 1,400 pounds will be the most profitable weight at which to finish cattle.

Feeding diet 1 to cattle from 600 pounds to finish at 1,400 pounds would require 304 days to finish, and cattle would consume 5,486 pounds of feed (DM basis). Average daily gain would be limited to 2.7 pounds due to the elevated consumption of hay, and cattle could be expected to consume 7.22 pounds of DM for every pound of gain. On average, diet 1 would cost $1.40 per head per day, and return a profit of $100.85 per head.

Diet 2 Analysis

When feeding diet 2, which contains 10 percent hay (DM basis), the increased NEg reduces the time on feed when compared to cattle fed diet 1. Similar inefficiencies in the feed-to-gain ratio (F:G) occur as cattle approach finishing weight, and these are to be expected. Finishing cattle past 1,400 pounds will be costly in all scenarios, which is why, as an industry, most cattle are killed at an average of 1,400 pounds. The cost of feeding cattle increases in diet 2 compared to diet 1, largely due to the difference in corn inclusion.

Compared to diet 1, diet 2 lessens the days on feed to 269 days and the total feed intake per animal to 4,848 pounds (DM basis). Average daily gain increases to 3 pounds and F:G decreases to 6.39 compared to diet 1. Diet 2 costs more per head per day ($1.46) when compared to diet 1 ($1.40). The combination of improved performance and cheaper feed results in a profit of $151.49 per head. With fewer days on feed, cattle can enter and leave the feedlot more frequently, generating more revenue.

Diet 3 Analysis

The primary difference between diet 2 and diet 3 is the change from expensive hay to inexpensive corn silage. Therefore, diet 3 is less expensive than the previous two diets. At 40 percent corn silage inclusion, diet 3 limits NEg, requiring more days on feed to finish cattle.

Cattle fed diet 3 will remain on feed for 278 days with a total DM intake is 5,010 pounds. Average daily gain is predicted to be 2.9 pounds and F:G 6.58. Where diet 3 really shines is in value. Feeding diet 3 costs a mere $0.81 per head each day and returns a profit of $314.39 per head.

Diet 4 Analysis

Diet 4 takes diet 3 one step further, still using the cheaper forage (corn silage), cattle fed diet 4 consume a 63 Mcal NEg per cwt compared to the 60 Mcal Neg per cwt fed in diet 3. This diet is more expensive than diet 3 but requires fewer days on feed. Cattle approaching finish weight still have inefficiencies in F:G, and finishing cattle past 1,400 pounds will be the most costly days on feed. Cattle fed diet 4 would be expected to remain on feed for 266 days and consume 4,798 pounds on a DM basis. These cattle are also predicted to gain 3.1 pounds per day and have the best F:G, at 6.31, of any previously mentioned scenario. Diet 4 will cost $1.08 per head per day, increasing the total cost for feeding steers when compared to diet 3. However, cattle fed diet 4 will grow faster than cattle fed diet 3, which decreases the yardage cost and returns a profit of $260.83 per head.

Conclusion

There are many different feeding strategies available for beef cattle producers. If you are finishing cattle, considering the NEg needed for growth and the economics of achieving that growth will go a long way toward the goal of profiting from finishing cattle. On the right diet, cattle feeding scenarios can be profitable. It is important to keep in mind that the scenarios provided in this article represent a snapshot in time, and the analyses do not take into consideration loss of performance due to castration, poor management, or morbidity and mortality. These are hypothetical scenarios to illustrate dietary comparisons across a singular system. To make a more accurate assessment of your operation, adjustments should be made for your production and feeding costs.

Source : psu.edu

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