Chapman, C. K., Extension Livestock Specialist, Utah State University
Garcia, M.D., Assistant Professor-Beef Cattle Genomics, Utah State University
Kunzler, M., Undergraduate Researcher, Utah State University

ABSTRACT

This study evaluated changes in performance of bulls enrolled in the Utah Beef Improvement Association’s (UBIA) annual performance tests conducted in accordance with central bull test standards established by the Beef Improvement Federation. Breeds with over 500 bulls enrolled over the period of 2004 to 2018 were included in the study. Traits evaluated included birth weight(BW), initial weight(INWT), adjusted 205-day weight(WW205), final test weight(FIWT), average daily gain(ADG), yearling weight(YW), and weight per day of age(WDA). Significant differences were seen across all breeds for BW and WW205, but not between breeds. Significant difference in rate of change when comparing breeds was significant (P < 0.05) for ADG, INWT, FINWT, YW and WDA.

Introduction

The Utah Beef Improvement Association (UBIA) has been conducting an annual bull performance test since 1972. The test has been conducted in cooperation with Utah State University Extension and commercial feedlots to house and feed the bulls.

In the 32-year period from 1987 to the 2019 bull test, the UBIA has tested more than 7,580 bulls at three different locations. The majority of bulls tested have been from Utah seedstock producers. However, bulls have also been enrolled in the test from Colorado, Wyoming, Idaho, and Nevada. More than 3,000 high-performance bulls have been sold for use in commercial and purebred herds throughout the western U.S. through the UBIA Performance Bull Test sales.

The primary objective of the test is to assist cattle producers in obtaining genetically-superior, performance-tested bulls that are structurally and reproductively sound. To this end, the UBIA has followed the standards set forth for central bull tests established by the Beef Improvement Federation (BIF, 2016). Allowing the bulls to grow using a primarily forage-based ration, provides them with adequate nutrients to express their genetic differences, while not pushing them so hard that the integrity of their digestive system is stressed or compromised.

As the cattle industry has worked to meet consumer demands for higher quality beef eating experiences, the seedstock industry has toiled to adapt their cattle to supply the commercial trade with the right type of cattle to meet their needs. This paper will discuss the changes that have been observed in bull performance relative to these industry changes over some of the recent history of the UBIA Performance Test (Test). Thus, the objective of the current study was to evaluate 14 years (2004-2018) of performance bull testing to determine genetic trends of bull selection in the state of Utah.

 

Materials and Methods

Experimental Animals

Beef bulls from any registered breed association have been allowed to participate in the test. Bulls are received annually at the test feedlot in early October. Until 2005, only calves born from January 1 to March 30 of the current calendar year were allowed to enroll in the test. Beginning with the 2005-2006 test, the test was divided into two divisions, a Jr. Division for spring-born bulls and a Sr. Division for bulls born the previous fall (September through December). In 2010, composite bulls were allowed into the test.

 

Bull Test Procedures

Prior to arrival, bulls must have been weaned for at least two weeks and accustomed to consuming dry forage diets. They must also have received pre-conditioning vaccines which include the following: Clostridium chauvoei (Blackleg) , Clostridium septicum (Malignant Edema), Clostridium perfringens Types C&D,  Infectious Bovine Rhinotracheitis (IBR), Parainfluenza₃  (PI₃), Bovine Respiratory Syncytial Virus (BRSV), and Bovine Viral Diarrhea (BVD). Vaccines for Mannheimia (Pasteurella) haemolytica and Pasteurella multocida or Heamophilus somnus are highly recommended, but are not required. It is also recommended that the bulls be treated with a parasiticide for both external and internal parasites within a month of the receiving date.

The receiving protocol is that the bulls received a booster vaccine of both 8-way Clostridial and 4-way Respiratory vaccines. Additionally, the bulls received an intranasal respiratory vaccine for immediate protection against BRSV, IBR, and PI₃, and since 2017 have received a prophylactic dose of Draxxin (Tulathromycin) to reduce the incidence of respiratory illness due to the stress of adapting to the new environment at the feedlot.

Beginning in 2008, an ear-notch tissue sample was collected from each bull to test for Persistently Infected BVD (PI-BVD). Samples were tested at the Central Utah Veterinary Diagnostic Lab. Since that time only one bull has tested positive for the disease.

In accordance with BIF standards, the bulls then entered a three-week warm-up period during which bulls are adapted from a dry forage ration to the test ration which is composed mainly of corn silage and alfalfa hay with supplemental steam-flaked corn to balance for energy and a vitamin/mineral supplement which includes Rumensin. In 2015, the UBIA reduced the warm-up period to two weeks in order to meet time frames imposed due to regulatory and market considerations following the end of the test. When available, locally-grown rolled barley replaced a small portion (<20%) of the corn in the ration. However, due to cost considerations and lack of consistent availability, this practice was ended after a two-year trial.

Following the warm-up period, the bulls were weighed twice with a day between weigh days. The weights were averaged together and this was the official beginning weight(INWT). This helped to reduce variability due to fill and water consumption. The same procedure was used at the end of the 112-day test period to determine final weights(FIWT). The bulls were always weighed prior to morning feeding so as to be as empty as possible.

Interim weights were taken every 28 days to check on the bull weight gains and to determine if changes in diet needed to be made in order to maintain a 3.0-3.5 pound test average daily gain across all bulls. However, these interim weights were only considered check weights.

To qualify for the UBIA Performance Test Sale, bulls must have achieved a combined sale index of 95.00 or higher. The combined sale index was a weighted index of both Average Daily Gain on Test (70%) and Adjusted Yearling Weight (30%). The gain on test portion was weighted higher as this is the actual measure of their performance on test. The yearling weight gives credit to pre-test performance and maternal traits. Approximately 60% of bulls on test achieved the 95.00 index or higher.

Additional sale requirements included, the bulls having an adjusted yearling weight of at least 1,000 pounds and passing comprehensive breeding and structural soundness examinations. Breeding soundness examination thresholds were in accordance with standards established by the Society of Theriogenology.

 

Statistical Analyses

Utilizing the Mixed Model procedures of SAS (version 9.4, SAS Institute, Cary, NC), changes in performance data for bulls participating in Utah Beef Improvement Association (UBIA) Bull Test from 2004 to 2018 were evaluated.  Birth weight (BW), adjusted 205-day weaning weight(WW205), initial test weight (INWT), final test weight(FINWT), average daily gain on test (ADG), adjusted yearling weight (YW), and end of test weight per day of age (WDA) were fit as random variables in the model and year and breed fit as fixed variables. Breeds with greater than 500 bulls evaluated with the statistical model and included Angus, Hereford, Red Angus and Simmental breeds. Interval regression analyses as described by Steele et al. (1997) were conducted to determine if improvement between breeds was significantly different.  Traits evaluated included BW, WW205, INWT, FINWT, ADG, YW  and WDA. 

 

Results and Discussion

Statistical analyses in the current study revealed that breeds did not differ in their rate of change for birth weight and weaning weight (Figures 1 and 2).

 

 

Figure 1. Means of birth weight, for the top represented breeds participating in the UBIA Bull Test from 2004-2018. Differing superscripts differ at a level P < 0.05.

 

 

Figure 2. Means of 205d adjusted weaning weight, for the top represented breeds participating in the UBIA Bull Test from 2004-2018.  Differing superscripts differ at a level P < 0.05.

 

 

Although no difference was detected between breeds, all breeds exhibited a decrease over time in BW and an increase per year for WW205. Much of the change in these weights are the result of market demand for bulls exhibiting these traits by buyers in the region. When breeds were not separated in the analyses it was determined that rate of change was significant for all traits evaluated in the current study.  These results were not in agreement with previous studies (Garcia et al., 1998; Howard et al., 2013), where significant differences among breeds was significant. However, while the data reported by Howard overlapped somewhat with the time period covered in the current study, the bulk of data from both Garcia and Howard is from a period of time earlier than the current study. This is significant in that the time periods covered by both the Garcia and Howard studies encompassed an era in the U.S. cattle industry that saw a significant transformation conformationally in the domestic cattle herds that moved cattle from the “old” style or type of smaller framed cattle which produced 500-550 pound carcasses to the modern type of cattle found in herds today that exhibit traits leading to 750-900 pound carcasses. This transformation resulted from considerable selection pressure in the seedstock sector and the development and widespread adoption of Expected Progeny Differences (EPDs). Additionally, both of the previously referenced studies were also conducted in different geographic regions and could reflect regional differences in cattle types developed for running under differing environmental conditions, even though some of the breeds were similar between all of the studies.

Statistical analyses did however reveal that rate of change when comparing breeds was significant (P < 0.05) for ADG, INWT, FIWT, YW and WDA(Figures 3-7). While there were significant differences identified in the current study, the level of change and type of change (positive or negative) were not in agreement with the previously described studies. For example, when evaluating ADG, all four breeds exhibited a decrease over time in their trend (Figure 3). The rate of change was not significantly different when comparing the Angus, Hereford, and Simmental breeds. However, the rate of change was significantly different when comparing Angus and Hereford to the Red Angus whose rate of decline was significantly (P <0.05) greater than the two previously mentioned breeds. This current study identified an overall decrease over time in average daily gain. This is not in agreement with the previously mentioned studies which observed an increase in average daily gain over time. However, this can be explained by the fact that the current study has a more forage-based ration to ensure that bulls are more functional after they complete the performance test. The previously mentioned studies were feeding much higher energy, feedlot finishing rations that most likely is the major contributor to the differences in trend lines over time when comparing studies. 

 

Figure 3. Means of average daily gain, for the top represented breeds participating in the UBIA Bull Test from 2004-2018. Differing superscripts differ at a level P < 0.05.

 

When evaluating INWT(Figure 4), the Simmental breed was not significantly different in its rate of change than any of the other breeds. However, when comparing the rate of change between the Hereford breed and the Angus and Red Angus breeds, the Hereford breed was significantly different (P <0.05) in its rate of change from the other two breeds. The current study observed a negative slope trend when evaluating INWT. This is most likely due to Utah producers identifying that larger type cattle were not performing well on limited rangeland resources and were making a concerted effort to moderate the size of the cattle to be more compatible with rangeland resources. While the current study observed a negative trend line, the previously mentioned studies still saw an overall positive trend increasing initial test weight. However, data collected from the last three years from the previously mentioned studies show a dramatic decrease in initial test weight for bulls entering their performance tests.

This was also similar when evaluating FINWT(Figure 5). For this trait the Angus, Hereford and Red Angus were all significantly different (P < 0.05) in their rate of change for FINWT, but were not significantly different from the Simmental breed. Furthermore, when evaluating yearling weight, the Angus and Simmental were not significantly different from one another with their rate of change over time for YW(Figure 6). However, they were significantly different from the Red Angus and Hereford, who also were significantly different from one another in rate of change over time for YW. Once again the decrease in final test weight and yearling weight trends most likely has to do with Utah producers having the foresight to make an effort to moderate cow size on rangeland production systems. While the previously mentioned studies exhibited a positive trend that showed increasing FINWT and YW, the last three years of data analyzed in those studies observed strong selection practices to dramatically decrease those weights. 

 

Figure 4. Means of initial test weight, for the top represented breeds participating in the UBIA Bull Test from 2004-2018. Differing superscripts differ at a level P < 0.05.

 

 

 

Figure 5. Means of final test weight, for the top represented breeds participating in the UBIA Bull Test from 2004-2018. Differing superscripts differ at a level P < 0.05.

 

Figure 6. Means of final yearling weight, for the top represented breeds participating in the UBIA Bull Test from 2004-2018. Differing superscripts differ at a level P < 0.05.

 

Finally, when evaluating WDA (Figure 7), the Hereford breed was significantly different (P<0.05) in rate of change from the Angus and Red Angus breeds but was not significantly different from the Simmental breed. No significant differences were detected between the Angus, Red Angus and Simmental breeds for weight per day of age. While the current study did exhibit a negative trend showing decreased weight per day of age over time, it is most likely due to a concerted effort to control mature cow size on the range.

 

 

Figure 7. Means of weight per day of age, for the top represented breeds participating in the UBIA Bull Test from 2004-2018. Differing superscripts differ at a level P < 0.05.

 

Conclusions

While the current study was not in agreement with previous bull test genetic trend studies (Garcia et al., 1998; Howard et al., 2013), the results herein show that UBIA and its’ member bull producers were on the forefront of making progress to have cattle that were specifically developed for the rangeland beef production systems of the Intermountain region. Specifically, the UBIA made a concerted effort to not only develop bulls on a diet that was compatible to what the bulls would be receiving when they were on a breeding pasture, but there was also an effort to produce bulls that would produce calves that were compatible with limited rangeland forage systems. As such, the UBIA bull producers have provided a great service to the Intermountain West in developing bulls that are compatible with rangeland production systems in the region.

 

Literature Cited

Beef Improvement Federation. (2016). Guidelines For Uniform Beef Improvement Programs. pp. 49-52  https://beefimprovement.org/wp-content/uploads/2013/07/BIFGuidelinesFinal_updated0916.pdf,  Accessed January 17, 2020.

Garcia, M.D., M.G. Thomas, W.R. Parker, V.R. Beauchemin, and R.M. Enns. (2004). Evaluation of Performance Trends in the Tucumcari Bull Test 1961 and 2000. New Mexico State University Agriculture Experiment Station: Research Report 754.

Howard, T.R., K. Bondioli, S. DeRouen, and M.D. Garcia. (2013). Evaluation of 54 years of centralized performance bull testing at the Dean Lee Research and Extension Center. AgCenter Bulletin Pub B-893. October 2013.

Steele, R., J. Torrie, and D. Dickey. (1997). Analysis of covariance. Principles and procedures of statistics: A Biometrical Approach. 3rd edition, McGraw Hill, Inc. New York, NY. 447-449.

 

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