2020 Annual Summary: Research at the Department of Animal and Food Sciences

This summary includes the recent research carried out in the Department of Animal and Food Sciences.

For more information check out P-1062  and Beef.Okstate.edu

Overview:

• Effects of Exercise and Roughage Source on the Health and Performance of Receiving Beef Calves (page 1)

  Introduction: Consumers are concerned about animal well-being and the quality of life for animals raised in confinement. Some of these concerns include a lack of exercise and the use of antibiotics. As producers continue to seek alternative methods to improve cattle health and well-being, exercise may be a method to accomplish this and ease consumer concerns. Cottonseed hulls and soybean hulls can effectively be used as roughage sources in diets for receiving calves due to the high fiber content. Feeding hulls as a roughage source can be beneficial for producers not equipped to process or handle long-stem roughages effectively. This experiment used 94 auction market purchased steers in four experimental treatment combinations to determine the effects of exercise (no exercise or 10 minutes of exercise three days per week) and roughage source (cottonseed hulls and soybean hulls or hay) on receiving calf health, performance, and fecal characteristics during a 56-day receiving period.

• Using a Dried Distillers Grains Cube as a Supplement for Steers Grazing Mixed-grass Prairie in Oklahoma (page 3)

  Introduction: Dried distiller’s grains have been a widely used supplement for cattle in various feeding operations. Little to no starch, high energy and high bypass protein content are a few of the main upsides to the use of DDGS in a cattle growing operation. However, loose DDGS have not been used extensively in a pasture setting due to the potential loss of product from wind or in the dirt and soil. Research was conducted on the effects of a distiller’s cube supplemented to growing steers grazing mixed grass prairie in western Oklahoma. This research was conducted at the Marvin Klemme Range Research Station near Bessie, Oklahoma in Washita County and at the USDA ARS Southern Plains Experimental Range [SPER] near Fort Supply, Oklahoma in Harper County to test the theory that stocking rates can be increased by replacing a fraction of the daily forage intake with supplementation while avoiding negative impacts on animal performance and native range condition. Three treatments were initiated at Fort Supply and two treatments were initiated at Klemme. Treatments at SPER were: 1) Negative Control, no supplementation, 2) Positive Control, supplemented with DDGS cubes 2 pounds per steer on alternate days in late summer, 3) High Supplement, 1/3 increase in stocking rate, 0.75% BW Supplemental DDGS cubes all season. At Klemme only the Positive Control (2.5 pounds per steer on alternate days in late summer) and High Supplement were included in the experiment. Steers at Klemme were assigned to six pastures, three stocked at four acres per head (High Supplement) and three pastures stocked at six acres per head (Positive Control). The SPER site had steers assigned to 12 pastures stocked at 3.5 acres per head (High Supplement) and 5.5 acres per head (Positive and Negative Control).

• Enterprise Budget Analysis of Dried Distiller’s Grains Cube Supplementation on Native Range (page 5)

  Introduction: Stocking rate is the fundamental management factor under producer control that has a major impact on animal performance and long-term sustainability of native range-based ecosystems. Producers are under significant economic pressures to maximize production per acre, which can prove harmful to the range condition, where desired forage species are overgrazed decline in the stand. Feeding high levels of supplemental feed based on corn co-products of the ethanol production industry can offset forage consumption by grazing cattle and lead to higher stocking rates, without the reductions in forage mass and animal performance. The objective of this project is to investigate the impacts of supplementation and increased stocking rates on performance of growing steers, economics of the stocker cattle enterprise, and range condition in two locations in western Oklahoma (Marvin Klemme Research Range, Besse Oklahoma and USDA ARS-Southern Plains Range Research Station, Ft Supply Oklahoma [SPRRS]). This report summarizes an enterprise budget analysis of two performance trials during the summer of 2019. At the Marvin Klemme Range Research Station there were two treatments, 1) steers stocked at six acres per steer and supplemented with 2.5 pounds of DDGS cubes per day during the late summer only (Positive Control) and 2) increased stocking rate of four acres per growing calf (33% increase in stocking rate) along with supplemental dried distiller’s grains cubes fed at a daily rate of 0.75% of bodyweight throughout the grazing season (High Supplement). The study site at SPRRS used the same treatments but included a negative control with no supplemental feeding and were stocked at 5.5 acres per steer for Controls and 3.5 acres per steer for High Supplement. The assumptions used in this analysis were based on actual costs of inputs for supplements offered and the 10-year average Oklahoma auction market prices for 450-pound steers in April and 750 pound steers in October. Other assumptions included: $189.29 per cwt purchase at 450; $152.81 per cwt sales at 750; $6 per cwt slide; $76 per head receiving cost; 79 pounds gain during rec for Bessie and 46 pounds gain during rec at Ft Supply; $750 per ton mineral (4 oz per day); $11 per acre rent; $0.10 per head per day yardage and care; and $548 per ton for DDGS cubes.

• Weaning Weight Trends in the U.S. Beef Cattle Industry (page 7)

  Introduction: Calf weight at weaning is often used as an indicator of productivity in cow-calf operation and represents a large portion of gross income. Improvements in management and genetic selection have resulted in increased weaning weights over the past several decades and genetic trends for pre-weaning growth have been steadily increasing since the 1980’s. Large breed association data sets are available representing seedstock operation trends. However, tracking regional or national weaning weight trends in commercial cow/calf operations is more difficult because few widely-used, standardized record systems exist. Therefore, the objective of this study was to characterize trends in commercial cow-calf enterprise calf weaning weight.

• Predicting Dry Matter Intake of Gestating and Lactating Beef Cows (page 9)

  Introduction: An accurate estimate of feed intake is a fundamental component necessary to determine nutrient balance and project animal performance. Most beef cattle nutritionists and computer modelers estimate the amount of feed that cows consume using equations developed and published by the National Academy of Sciences, Engineering and Medicine (NASEM); Nutrient Requirements of Beef Cattle. The NASEM beef cattle committee has published several equations intended to provide general guidance for feed intake of beef cows (1984, 1987, and 1996). In the most recent publication (2016), the NASEM committee recommended continued use of the equation developed in 1996. In addition to these equations, Hibberd and Thrift (1982) published tabular values estimating feed intake in beef cows based on stage of production and forage quality or energy concentration. This table has served as a widely used guideline to estimate feed intake in beef cows over the years. These equations and tabular values were developed using a considerable amount of feed intake data calculated from internal or external marker-based approaches and most of those studies were conducted or published in the ‘70s, ‘80s and ‘90s. The objective of this study was to validate these equations for predicting feed intake in beef cows.

• Review of Literature Reporting Phenotypic and Genetic Correlations for Feed Intake in Growing Cattle and Beef Cows (page 11)

  Introduction: The beef cattle industry has recently adopted expected progeny differences (EPDs) to estimate genetic merit for feed intake (FI), residual feed intake (RFI) and residual average daily gain (RADG). These selection tools are calculated using phenotypic data from growing animals fed a total mixed ration in confinement. Feed intake and efficiency traits are considered to be moderately heritable. For example, Berry and Crowley (2013) reviewed 45 experiments where heritability of average daily gain (ADG), body weight (BW), FI, and RFI were determined in growing animals. The pooled heritabilities across all studies were 0.31, 0.39, 0.40 and 0.33 for ADG, BW, FI and RFI, respectively, suggesting that substantial genetic improvement can be made in feeder calves for these traits. However, a primary consideration is whether selecting for growing and finishing period efficiency results in improved forage utilization in the cow herd. After all, approximately 70% of feed energy used in the process of beef production is consumed by the cow herd (Gregory, 1972), and increasing efficiency of feed utilization in cows should be a primary economic selection criterion. Considerable research has been published during the last 20 years related to feed efficiency traits in growing cattle consuming high-quality diets, however, relatively little is known about the genetics of low-quality forage utilization efficiency in beef cows.

   

  Beef Improvement Federation guidelines require a minimum diet energy concentration of 2.4 Mcal ME/kg feed (DM basis). This is approximately equivalent to 67% total digestible nutrients or 0.43 Mcal of net energy for gain (NEg) per pound of feed. Since this is a minimum requirement, many test diets contain around 70% to 74% TDN or 0.47 to 0.53 Mcal of NEg per pound of feed DM. This degree of diet energy concentration (or digestibility) is equivalent or beyond the absolute peak of forage digestibility in almost any environment. In most grazing systems beef cows spend more than half of the year consuming moderate to low-quality forage ranging from 48% to 60% digestibility. Differences in diet quality combined with differences in physiological maturity represent the potential for a genotype by environment interaction (GxE) regarding genetic potential for feed intake or feed efficiency. In other words, mature animals consuming moderate to low-quality forage diets may re-rank compared to their ranking established during a test period that was conducted while they were 8 months to 14 months of age, growing rapidly and consuming a high-quality diet. Thus, the factors that must be considered before selecting on existing feed intake and efficiency metrics in the industry (derived from high-quality diets and growing animals) to improve cow feed intake and efficiency are a) evidence of high genetic correlations over time (age and stage of production) and b) high genetic correlations between measures collected using a wide range in diet characteristics.

• Effects of Weaning Timing on Performance and Energy Utilization in Beef Cows (page 13)

  Introduction: Compared to mature cows, two-year-old first-calf heifers give less milk, wean lighter calves, take longer to reinitiate estrous cycles after calving, and generally have lower pregnancy rates. In addition, previous research indicates that lactation increases maintenance energy requirements of the beef cow by approximately 20% (NASEM, 2016). Early weaning should eliminate the nutrients required to produce milk and at the same time, reduce the cow’s maintenance energy requirements. This feed energy savings could be redirected to calf growth by feeding the calf directly. Therefore, the objective of this study was to determine the effects of timing of weaning on energy utilization and production efficiency in first-calf beef heifers and their calves.

• Maintenance Energy Requirements and Forage Intake of Purebred vs Crossbred Beef Cows (page 15)

  Introduction: While crossbreeding has historically been used to increase growth, milk yield, weaning rate and longevity, there may also be opportunities to capitalize on breed complementarity to reduce feed intake and input costs. One method to better match beef cows to lower input production systems is to use a crossbreeding system that balances breeds with high output with a breed of lower feed intake. For example, in MARC data, Hereford cattle average about 42 pounds less yearling weight and 21 pounds less WW due to milk, compared to Angus. Recent MARC data also documented 2.1 pounds per day less feed intake in heifers fed a forage-based diet. Therefore, the objective of this study was to determine maintenance energy requirements, voluntary feed intake, and efficiency of preweaning calf growth for Angus and Hereford X Angus cows.

• Validating Genomicaly Enhanced EPDs for Intake in Mature Cows Consuming a Hay Diet (page 17)

  Introduction: Genotyping platforms currently available to rank animals for dry matter intake were developed using growing animals fed a high-quality diet. High-energy, high-protein diets are used to develop these markers because the objective is to facilitate expression of genetic differences in growth and feed intake under typical post-weaning management (growing and finishing) conditions. It is unknown whether genomic markers or genomically-enhanced expected progeny differences (GE-EPD) can be used to reliably rank mature cows consuming a lower quality forage diet. For that reason, we initiated a project to determine the relationship between currently available GE-EPD for dry matter intake (DMI) and actual feed intake of beef cows consuming a grass hay diet.

   

  In the first year of this study, 40 Angus cow/calf pairs were used (first calf heifers n=21, mature cows ≥ 3 years old n = 19), each assigned to one of five dry-lot pens according to the DMI GE-EPD of the dam. During late lactation (January through April), the pairs were provided abundant bermudagrass hay, mineral and 5 pounds of dried distiller’s grains with solubles daily. Milk yield and composition were determined monthly using a milking machine. After weaning, cows were returned to the pens and hay (CP = 5.7%, NDF = 66.4, TDN = 54%) intake was determined using SmartFeed individual intake units. To ensure adequate protein supply and positive energy balance, 2 pounds of corn and 2 pounds of cotton seed meal were provided daily. Following a 14-day adaptation period, individual cow forage intake was measured for 45 days.

• Ionophores and Implants Affect Performance and Carcass Characteristics in Hair Sheep (page 19)
  Background: The use of growth promoting technologies can result in improved feed efficiency and increased lean deposition in ruminant animals. However, unlike in the beef industry, the sheep industry has had varying success when using growth promoting technologies. Historically, wool breeds have demonstrated some improvement in lean deposition and feed conversion when implanted with zeranol, but also have demonstrated increased incidence of rectal prolapses in some cases. Lambs also may be fed ionophores, such as lasalocid, in order to prevent coccidiosis. In some cases, lambs fed ionophores have demonstrated improvements in average daily gain and feed efficiency. A recent trend in the U.S. sheep industry has been the increased production of hair sheep. Hair sheep are better adapted for higher ambient temperatures, have improved parasite tolerance, and do not require tail docking or shearing. In addition to these benefits, it is possible that hair sheep may respond differently to growth promoting technologies than wool sheep. This experiment utilized 30 crossbred hair whether lambs to determine the effects of dietary inclusion of lasalocid in combination with zeranol implants on performance, carcass characteristics, and economic returns.
• Utilizing Cotton Byproducts in a Beef Cattle Finishing Diet (page 21)
  Background: Many feedlot finishing diets utilize a low to medium quality hay as the primary roughage source; however, hay can be expensive when compared to other available low to medium quality plant byproducts. In the southwestern U.S., a recent increase in cotton production has resulted in greater availability of byproducts such as cotton gin trash and whole cottonseed for use in beef cattle diets. Cotton gin trash is a low-quality byproduct that is high in effective fiber and consists of stems, burrs, lint, leaves, immature cottonseed and dirt. Whole cottonseed provides additional fiber and can also be used as a source of fat and protein in the diet. This experiment was conducted using 64 crossbred beef steers to determine the effects of including cotton byproducts in a finishing ration on steer performance and carcass characteristics. The treatment diet (CTN) provided the fat, protein and fiber components of the diet using whole cottonseed and cotton gin trash. This was compared to a control diet (CON) which provided the fat, protein, and fiber components using Sweet Bran, prairie hay, and a molasses based liquid fat supplement.
• Heifer Development: A Grazing Systems Approach to Sexed vs Conventional Semen (page 23)
  Introduction: Limited research exists identifying performance and economic advantages for implementing a grazing management system to reduce feed cost by utilizing options like rotational grazing and cool season forages components. Oklahoma producers rarely utilize grazing management techniques to improve their bottom line completely with grazing systems and artificial insemination.
• Novel Packaging Improves Dark-cutting Beef Color (page 24)
  Background: The characteristic bright cherry red lean muscle color of beef carcasses at the 12th/13th rib interface is a desirable trait during grading. Dark-cutting carcasses are an example of a color deviation which results in discounted carcass value. In 2000, the U.S. beef industry lost approximately $165 to $170 million due to the occurrence of dark-cutting beef. Later in 2011, the National Beef Quality Audit reported 3.2% of carcasses graded were assessed as darkcutting. Although in 2016 National Beef Quality Audit, the level of dark-cutting beef has decreased to 1.9%, dark-cutters remain a quality defect worldwide. Lowering the muscle pH by lactic acid enhancement increased redness of darkcutting steaks. Similarly, high-oxygen modified atmospheric packaging enhanced the color of darkcutting beef by providing additional oxygen for myoglobin. Hence, the overall objective of this study was to determine the combined effects of aging, antioxidant enhancement, and MAP on the lean muscle color of dark-cutting beef during simulated retail display.
• Competition for an Automated Supplement Feeder Affects Behavior of Stocker Steers (page 25)

  Background: Automated feeding equipment has recently been developed for supplementing grazing cattle, and researchers and ranchers are interested in evaluating the potential cost-effectiveness of these units. The feeder (Super SmartFeed, C-Lock, Inc.) consists of a large feed bin that dispenses feed into four feeding stations. Each feeding station is accessible to one animal at a time and each station is controlled by the feeder electronics. Feed dispense is triggered by an animal’s RFID tag.

   

  If the animal is eligible for feed, supplement is dispensed, until the limit is met. Mixed breed beef steers were used in this trial and were sourced from sale barns. The experiment was conducted in the summers of 2018 and 2019 at the OSU Bluestem Research Range with steers grazing bermudagrass and supplemented with cottonseed meal through the automated feeder.

   

  The experimental treatment was stocking density of the feeder. Therefore, each week, different numbers of steers were commingled and given access to the feeder to vary the stocking density at the feeder. The location of tester steers was recorded for both years with a GPS unit. In 2019, pedometers were also employed to count the steps taken by the tester steers.