Balancing The Amino Acid Requirements of Backgrounding Calves Increases Profits

Research Period: October 1, 2020, to September 30, 2021.

Report Date: October 29, 2021

SUMMARY OF RESULTS

Forage-Based Diets

Calves fed a balanced Amino Acid SBM treatment had over a $0.20 per Lb. cost of gain advantage.

Rep 2 (no severe weather) using the balanced AA supplement netted approximately $40 more per head over feed costs than calves fed a DDG supplement.

By-Product Diets

Calves fed the ESBM diet had increased value of $11 per head compared to calves fed a DDG diet

Introduction

Under grant from the United Soybean Board Boveta conducted a trial to show the effects of balancing diets for backgrounding cattle using soybean meal.

Beef calves typically flow through three production categories: cow-calf, backgrounding, and finishing. Backgrounding calves typically describe calves from weaning to approximately 700 Lbs. in body weight. Backgrounding calves gain a high proportion of lean tissue (muscle) growth during this phase. This creates the opportunity to feed calves forage-based or fiber-based (by-products) diets. A concomitant goal is to prevent excessive fat deposition. Calves that have a visual appearance of lean and skeletal (frame) growth will attract a premium at point of sale.

Typical approaches to formulating supplements for forage-based (pasture or hay) and by-product diets is to meet a crude or metabolizable protein target. Often protein sources used are corn-based (distillers’ grains) that do not balance amino acids digested by the calf to the calf’s amino acid requirements. There is no crude or metabolizable protein requirement. If an amino acid deficiency exists two problems will occur. One, efficiency of energy use is reduced likely resulting in increased cost of gain. Two, inefficiency of energy use will result in reduced skeletal and lean growth and increased fat deposition by the calf, reducing its liveweight value. Additionally, growth performance post backgrounding will be reduced.

The goal of this research was to determine if balancing amino acid requirement in diets typically used in backgrounding calf production would improve growth performance and calf value. The objective was to determine the growth response in calves fed a soybean meal protein supplement compared to distillers’ grain supplement.

Protocol

Two experiments were conducted. Animal management was typical of commercial backgrounding facilities. Animal management adhered to Animal Welfare guidelines. Forage based diets were fed in two replicated experiments in southern Illinois and by-product diets were fed in an experiment conducted in east central Missouri. Both locations are commercial production facilities, and the environment was typical where the experiments were conducted. Calves were procured from commercial auction facilities and/or commercial cow-calf producers. At arrival calves were vaccinated and dewormed per facility protocol. The calves were fed hay and a receiving supplement for at least two weeks prior to experiment initiation. During this time, any respiratory infections were treated (antibiotics) and calves were determined as healthy at experiment initiation. At experiment initiation calves were weighed and randomly assigned to pens. Calves had ad libitum access to water. Diets fed to calves were offered daily. Calves fed forage-based diets were fed a set amount daily based upon predicted energy and amino acid requirements. Calves fed by-product diets were allowed ad libitum consumption of diet. The amount of diet fed was determined by following a clean bunk protocol, where feed was delivered daily based upon previous day consumption and animal behavior. Experiments were ended when the calves had reached approximately 90 days on feed or when body weights were visually assessed to approximate 700 Lbs. Experiment termination was based upon commercial management of when backgrounding calves would be marketed to a feedlot. Calves were weighed at experiment end. Measurements made were body weight and feed offered (intake), and these data were used to calculate average daily gain and feed to gain. Diet costs were used to calculate feed costs.

Results

Ingredient composition of diets fed are presented in tables 1 and 3. Growth performance results are presented in table 2 (forage-based diet experiment) and table 4 (by-product experiment). Analysis of amino acid balance and cost and value of balancing diets to meet projected amino acid requirements are presented in tables 5 and 6.

Forage-Based Diets

Calves fed the forage-based diets were managed as two replicates, with three pens of 15 head assigned to each diet in both replicates. The first replicate was conducted during winter when an unseasonably cold period of approximately three weeks impacted growth of the calves. For this reason, data are presented separately for both replicates. Intake was designed to be different in replicate one, but intakes of supplement offered in bunks were not completely consumed by calves fed DDG diet. Supplement (non-hay) was fed daily into bunks during the morning. Calves on the DDG treatment were targeted to receive 8 Lbs. of supplement daily and calves on the SBM treatment were targeted to receive 6.5 Lbs. of supplement daily. The SBM supplement was fed to provide amino acids required to maximize efficiency at 2.5 Lbs. average daily gain. Hay (square bales, 60 Lbs.) was placed into feed bunks after supplement feeding. Hay was fed ad libitum to calves. Minimal hay waste occurred. Differences in diet formulation were replacement of DDG with AminoPlus (rumen-stable soybean meal) and increased percentage of hay in SBM diets.

Statistical analyses were done on intake, average daily gain, and end body weight. Statistical difference was significant for intake due to design of the study. Gain and body weight did not differ statistically between treatments. Therefore, mean values are presented. Differences between replicates was attributed to weather, specifically cold stress during replicate one. In both replicates the amount of supplement consumed was lower for calves fed SBM than DDG treatment diets, as designed. Even with lower supplement intakes, calves fed SBM had numerically greater gain. Balancing diets for predicted amino acid requirement resulted in greater feed efficiency of backgrounding calves.

Percent of amino acid requirement met by the diet based on body weight and gain of the calf was predicted (Table 5). Amino acid supplied was calculated as the sum of microbial amino acid and diet protein flowing from the rumen weighted for absorption efficiency at the intestine. These estimates were based upon estimates of carbohydrate digestibility and protein digestibility in the rumen. Amino acid requirements were based upon estimates of maintenance and tissue (protein) growth amino acid requirements. Percent of amino acid requirement was calculated as percentage of absorbable amino acid supplied to amino acid required. In replicate one and two, even though supplement intakes differed between treatments, the percent of amino acid requirement supplied was near 100. Arginine, methionine, and lysine were the only limiting amino acids and arginine and lysine were the only amino acids estimated to be below the predicted requirement. There is a limit to accuracy that our model can predict, and ingredient nutrient profile can range to a point where predictive values are influenced. Also, calves used in these experiments were small to average framed calves which would affect protein accretion and amino acid requirement. Given these caveats, predicted amino acid requirement was still in agreement with growth data. This being the case, what can be inferred from these data are that amino acids were limiting growth performance of these calves and increasing limiting amino acids improved growth performance of the calves.

Results

Replacing DDG with AminoPlus resulted in greater supplement cost ($ per ton). This was expected and is skewed to a point due to current pricing of soybean meal relative to DDG at time this experiment was conducted (favorable pricing for DDG). However, the greater proportion of corn in the SBM supplement and the lower feeding rate for the SBM supplement resulted in lower supplemental feed costs. Calves fed the SBM treatment had over an $0.20 per Lb. cost of gain advantage. Both replicates had a net advantage for the SBM treatment, but replicate one was confounded due to cold stress conditions. Replicate two would represent a more typical production environment, where calves fed the SBM supplement netted approximately $40 more per head over feed costs than calves fed DDG supplement.

By-Product Based Diets

The primary difference in ingredient composition of by-product-based diets was distillers’ grain being replaced with extruded soybean meal (ESBM). Samples of the ESBM were analyzed for rumen protein degradability and that information was used in predicting amino acid protection in the rumen. The diets were mixed and delivered into bunks once daily by a feed truck. This experiment was also conducted as two replicates.

Feed delivered was determined by reading bunks daily. Calves fed the SBM diet had greater intakes than calves fed DDG diet, with feed intake increasing approximately 5% over DDG calves. Average daily gain was calculated for each individual and compared between treatments using a paired T test in excel. Calves fed SBM diet had greater average daily gain in both replicates. The SBM diet also improved feed to gain approximately 4% over the DDG diet. Using the extruded soybean meal to balance diets to meet amino acid requirement of calves improved feed efficiency and average daily gain.

As described above, the goal of this research was to determine the effect of using soybean meal to meet amino acid requirements and effect on production economics. Inputting the diet and growth data into our prediction model, lysine was the first limiting amino acid. Our analysis predicted that amino acid supply rather than energy was limiting growth of these calves. The DDG diet was calculated to supply 92% of lysine required and the SBM diet supplied 97%. Using extruded soybean meal to balance for amino acid requirement improved growth performance of backgrounding calves fed a by-product-based diet.

Results

Diet cost ($/ton) was higher for the SBM diet than the DDG diet. This was expected due to the price difference between distillers’ grain and extruded soybean meal. The improved feed to gain by calves fed the ESBM diet however made feed cost of gain similar between the two diets. The greater average daily gain supported by the ESBM diet resulted in heavier calves at end of the backgrounding period. To assess the net value of calves, a purchase price of $1.40 per Lbs. and a sell price of $1.35 per Lbs. were used. These prices were based on average actual price of calves when purchased and local auction market value of 750 Lbs. calves at experiment end. Calves fed ESBM diet had increased value of $11 per head compared to calves fed DDG diet. Balancing diets to meet amino acid requirement of backgrounding calves increased profitability.

Summary

Previous research had shown our capability to predict amino acid absorption from diets by ruminants. Previous research had also shown growth production improvements by calves when fed diets balanced for amino acid requirement. The goal of this research was to measure the effect of balancing diets typically fed to backgrounding beef calves to meet amino acid requirements. A specific target of the research was to assess the economic effect on backgrounding production. Because the majority of beef calves are backgrounded on either a forage-based diet or diets containing fibrous by-products, both diet types were evaluated. Soybean meal was used as the protein source to supply limiting amino acids. Soybean meal is uniquely suited for this purpose due to its complimentary amino acid profile. This research demonstrated the nutritional superiority of soybean meal to distillers’ grains (and other protein sources) and provides evidence to replace cost of protein approach with cost of value approach when formulating beef diets.

When soybean meal was used in diets for forage-fed calves the same or greater growth performance could be achieved with less supplement. This not only reduced feed costs to the producer but would allow greater use of feed produced on-farm. A greater return to the farm could be realized and reduced waste nutrient production on the farm. When soybean meal was used in diets composed of oilseed and grain by-products, average daily gain, feed efficiency and animal value was increased. If an $80 per head profit is assumed, soybean meal improved profitability of calves by 10 to 18%.

Soybean meal is unique in complementing amino acid deficiency of beef diets. Rumen protection strategies are readily available for treating soybean meal. These data show that balancing diets to meet predicted amino acid requirements, with soybean meal, substantially improved profitability of backgrounding calf production. These results also can be used to show that using soybean meal would benefit environmental aspects of beef production. Finally, while not measured in this experiment, the improved growth performance of calves fed SBM diets would be expected to improve productivity during the finishing phase of production by having reduced illness and improved growth performance.

Table 1. Ingredient composition of diets

Table 2. Growth performance results from calves fed a forage-based diet (Rep 1 11/30/2020 to 2/25/2021; Rep 2 6/5/2021 to 8/24/2021)

Table 3. Ingredient composition of by-product-based diets

Table 4. Growth performance results from calves fed a by-product-based diet

Table 5. Amino acid requirement and financial results of calves fed a forage-based diet

Table 6. Amino acid requirement and financial results of calves fed a by-product-based diet