Balancing Corn-Based Diets with Soybean Protein to Meet Amino Acid Requirements Improves the Growth Performance of Finishing Beef Calves

Goal

This research is part of a larger research portfolio to measure the benefit of balancing beef diets to meet amino acid requirements for maintenance and growth. Soybean protein (meal and processed meal to increase rumen escape of protein) is used to optimize diets for amino acid to energy density of the diet. The goal of this research is to change the approach to diet formulation of beef cattle by using soybean meals to balance for amino acid requirements with the result of decreasing cost of gain and increasing carcass value.

Background

Our previous research  has shown that post-ruminal microbial and diet amino acid flow in cattle can be predicted with accuracy. This led to research that measured the improvement in feed efficiency when beef cattle diets were formulated to meet amino acid requirements rather than formulating diets to meet a crude protein or metabolizable protein requirement. We are now building a production scale research portfolio to demonstrate the advantage to producers if they formulate for amino acid requirements. The previous year we conducted an experiment showing benefits of our approach to forage-based diets such as most backgrounding (400 to 800 Lbs.) entities would use. The present research examines the response potential from balancing to meet amino acid requirement in starch-based (corn) diets. The key activities were to measure growth performance (feed efficiency and average daily gain) and carcass value effects when diets were balanced for amino acid requirements as compared to Industry-standard diets using distillers’ grains and formulated for metabolizable protein requirement.

Objectives

The original objective was to measure growth performance and carcass effects of calves fed a corn-based diet balanced to meet amino acid requirements compared to an industry-standard diet formulation (Tables 1 to 4).  The hypothesis of this experiment was that balancing corn-based diets to meet amino acid requirement would reduce feed intake without effect on daily gain, resulting in improved feed efficiency. The second hypothesis was that the improved cost of gain from better feed efficiency would overcome a higher diet cost due to balancing for amino acid requirement.  And the third hypothesis was that the intake and growth differences would improve carcass weight and yield grade.

Timeline Deviation

The original timeline for this experiment was to terminate September or October 2022. Heat stress encountered affected the project timeline. A period of approximately 8 weeks occurred during summer that impacted intake of the calves, and concomitantly gain. This was the same time period that reports of extensive death from heat stress was occurring in feedlots in the Midwest and West. Fortunately, we did not experience death in the calves, but intakes did drop to 50% or lower than expected during this time. This lengthened the timeline needed to complete the project. Also, the calves are performing well at their current body weight so they will be maintained on experiment until growth slows (reach mature weight). This strategy would be more aligned with commercial production and will maximize harvest value of the calf.

SUMMARY OF RESULTS

Intake was reduced (15%) but daily gain was also reduced (3%) in calves fed the balanced diet. Feed efficiency was improved 11%. The difference in gain is expected to be gone when final weights of calves are measured at the point of harvest based upon growth since the period of heat stress that occurred during the conduct of this experiment. The difference in intake between the two diets has been maintained. Cost of Gain for the AA balanced diet was $.07/Lb. less than the control. Carcass data is not available at this time as harvest is not complete.  That data will be added to this report when obtained (Q1 2023).

Protocol

Calves were purchased from a commercial auction facility. Upon arrival calves were taken through a 28-day protocol similar to that described above but all calves were managed as one group fed the same receiving supplement. After the receiving period calves were managed as one group and fed supplement and alfalfa hay to achieve daily gain between 2 and 3  per day. The approach used was to produce calves through the backgrounding phase that had daily gain similar to commercial backgrounding yards. Calves were fed similar to calves fed the amino acid balanced diet from preceding year research. The target was to start calves on this study weighing between 800 and 900 Lbs. Calves were started weighing in the high side of this range.

On day 0 calves were randomly placed into pens (approximately 30 head per pen, three pens per treatment). Pens were equipped with 32 feet of bunk space and automatic drinkers. Calves were fed one of the two diets listed in Table 5. Ingredients except oil and corn were mixed as a supplement by Buchheit, Inc and delivered by auger truck to the research facility and placed into 8-ton upright bins equipped with an auger for unloading into the mixer wagon. Oil was stored in totes and corn was stored in grain bins. A Rotomix mixing wagon was used to mix diets. Corn was added first followed by supplement and then soybean oil. Diets were allowed to mix a minimum of 3 minutes prior to feeding. Diet was offered to calves once daily in the morning. Bunks were read prior to feeding each day and adjusted accordingly. Calves were raised no more than 1 Lbs. per head per day every third day. Calves were started on feed at 1.5% of body weight. Feed was increased following the 1 Lbs. per head per day every third day if bunks had saliva present and calves were exhibiting hunger behavior. Calves were weighed approximately every 30 days. Calves were to be marketed when their rate of growth had lessened and/or when visual appraisal assessed the calf to be finished or at mature body weight. Calves will be harvested by National in Dodge City and carcass data collected on individual animals (carcass weight, yield grade, quality grade, ribeye area and backfat).

Results (5/26/2022 to 10/05/2022; carcass data not yet included)

Calves fed the DDG-based diet had consistently greater intakes than calves fed the soybean meal-based diet. Through 10/05 balancing diets for amino acid requirement reduced feed intake 15%. The calves fed DDG-based diet have exhibited a faster growth rate, but only 3% greater or 0.1 Lbs. greater ADG. Feed efficiency has been greater for calves fed the soybean meal-based diet, with an 11% improvement in feed efficiency. These results have aligned with the hypothesis that balancing diets for amino acid requirement would result in improved feed efficiency.

Using soybean protein to balance diets for amino acid requirement increased diet cost $10 per ton, which in our experience is typical. Generally, diet cost increases range between $5 to $15 per ton. However, the improved feed efficiency resulted in a lower cost of gain. Adjusting the diet with soybean meal protein to balance for amino acid requirements reduced feed cost of gain from $0.95 per Lbs. to $0.88 per Lbs. of gain. To date (approximately 127 days) this has resulted in $28 per head advantage for calves fed the soybean meal protein diet. When these calves finish (1300 to 1400 Lbs.) the advantage should increase with potential for increased carcass value as well.

Discussion

The amino acid-balanced diet was formulated to support 3.8 Lbs. of daily gain. As noted above the uncharacteristic heat stress that occurred caused the calves to miss this mark. It is noted that since heat stress has abated calves are gaining above this average. The slower growth than expected resulted in oversupply of amino acids. The three most limiting amino acids in these diets was lysine, arginine and methionine. The amino acid-balanced diet was predicted to supply 136, 134 and 138%, respectively, of these three amino acids. The effective energy ratio (EE Ratio) was 0.95, meaning calves consumed 95% of the energy predicted to be required for this level of gain. These data would be interpreted that energy was limiting gain and not amino acids, which is what the formulation of this diet was to achieve. Calves fed the DDG-based diet had an EE Ratio of 1.06, meaning these calves consumed more energy than predicted to be required. Interesting is that the EE Ratio of 1.06 would be interpreted that calves could have improved feed efficiency by 6 %. This number is within agreement of the 11% difference in feed efficiency measured between these two diets. Calves fed the DDG-based diet had predicted lysine and arginine supplied at 99 and 102% of requirement. These data could be interpreted that amino acid deficiency limited gain and growth performance of calves fed DDG-based diet rather than energy.

Future Direction

When the cattle are harvested to complete this study, we expect to see the same trends continue. Particular focus is on the difference in feed intake and expectation that no difference between diets will be measured for ADG. The 15% reduced intake with no difference in ADG would mean 15% less feed consumed with the same level of meat yield (potentially more based on previous data). The 15% reduction in intake would be a linear decrease in methane production (greenhouse gas emission) and a 15% reduction in land footprint needed to produce beef.

Table 1. Ingredient Composition (%) of Diets Fed to Calves

Table 2. Nutrient Composition of Diets Fed to Calves

Table 3. Growth Performance of Calves Fed Diets Differing in Amino Acid Balance (5/26/2022 to 10/5/2022)

Table 4. Diet Costs and Feed Costs of Diets Fed