2022 Annual Summary
We are proud to present a summary of research accomplishments from this past year. Whether basic or applied, the mission of our research program in the Department of Animal and Food Sciences is to solve problems and capitalize on opportunities in animal agriculture, companion animals, and the food industry.
This report summarizes a wide array of research activities conducted at our livestock units and in our laboratories by faculty, staff, and students. We hope to build on the Department’s rich history of excellence in research to better serve animal agriculture and help provide all citizens abundant affordable and safe food supply.
Impact of nitrite-embedded packaging and enhancement on dark-cutting raw and cooked
beef color (page 2)
Justification and Actions: Dark-cutting beef has a higher pH postmortem due to increased stress caused by many factors, including transportation, weather and handling. A greater than normal pH (> pH 6) provides a darker appearance upon blooming and a pink cooked internal color of fresh beef. These attributes are negatively perceived by consumers due to the association of a bright cherry red color and freshness. Therefore, dark-cutting beef reduces carcass value. Novel nitrite-embedded packaging (NEP) has been shown to improve the redness of dark-cutting beef. However, the understanding of retail color stability, cooked color and palatability of enhanced dark-cutting steaks stored in NEP and the effects repackaging in polyvinyl chloride (PVC) overwrap on retail color are limited. Therefore, the objectives of this study were to (1) determine the effects of NEP and enhancement on the dark-cutting beef color, (2) investigate the impact of repackaging in polyvinyl chloride on the redness of dark-cutting beef and (3) evaluate the effect of enhancement and packaging on cooked color and palatability. Dark-cutting beef strip loins (n = 8; pH = 6.39) and USDA Choice beef strip loins (n = 6; pH = 5.56) were selected at a commercial packing plant. Dark-cutting loins were divided into two sections and randomly selected as non-enhanced dark-cutting (DC) and enhanced dark-cutting (DCE) treatments with 110% pump of the green weight. After enhancement, a final concentration of 0.5% glucono delta-lactone and 0.1% rosemary was measured in the loins. Steaks (0.75 in) were removed from non-enhanced normal pH, DC and DCE loins with steaks randomly assigned to three, six or nine days in dark storage. Normal pH and DC steaks were vacuum packaged while DCE steaks were packed in NEP. All steaks were stored in dark storage until three, six or nine days then repackaged in PVC and displayed for six days. During dark storage, the instrumental color was evaluated every 24 hours, and upon repackaging, instrumental and visual color (n = 6) was evaluated every 12 hours. For objective three, steaks for cooked color were placed in dark storage for 72 hours after packaging the DCE steak in NEP and the DC and normal pH steaks in vacuum packaging. A trained sensory panel (n= 6) evaluated sensory steaks for beef palatability.
Changes in protein profiles influences muscle-pH and color of atypical dark-cutting
and normal-pH beef (page 4)
Justification and Actions: The color of meat is an important deciding factor in consumers’ assessment of meat quality. To meat buyers, the bright cherry-red color of meat indicates freshness and wholesomeness. However, atypical dark-cutting beef represents dark colored meat with a muscle pH between 5.6 and 5.8. Although previous studies have indicated that the ultimate pH of atypical dark-cutting beef is greater than normal, the mechanistic basis for the occurrence is not clear. Therefore, the objective of this study was to identify proteins related to the development of atypical dark-cutting beef. Longissimus thoracic (LT) muscles from 12 different animals (6 atypical dark-cutters and 6 normal-pH beef) were analyzed by comparing differences in protein levels using mass spectrometry-based analysis.
Effects of natural antioxidants in ground beef packaged in multiple packaging types
Justifications and Actions: Consumers relate the color of meat to freshness and base their purchasing decisions on color more frequently than any other quality trait. When purchasing beef, studies show that consumers want to see a bright cherry red color, deeming other color deviations as unacceptable. Ground beef is the most commonly purchased beef product in the U.S., and consumers prefer to purchase their ground beef in traditional foam trays with polyvinyl-chloride overwrap (PVC). However, meat in PVC has a limited shelf life, so the use of a master package (MP) or modified atmosphere packaging (MAP) is often used to extend shelf-life during transportation and storage. In a MP, fresh beef or pork products are first packaged in traditional PVC and placed into a large bag then flushed with gas, such as carbon monoxide (CO), nitrogen (N2) or carbon dioxide (CO2) to create an anaerobic condition. Various factors contribute to the discoloration of meat; thus, the objective of this project was to determine the effects of adding rosemary and green tea to ground beef patties for their antioxidant properties. Additionally, packaging types were also evaluated with the goal of extending shelf life. USDA Low Choice chuck rolls were purchased and ground together. Rosemary, green tea and a combination of rosemary + green tea were added to ground beef and formed into patties. Patties were packaged into PVC, MAP or MP. Both MAP and MP were flushed with the same gas blend of 0.4% CO, 69.6% N2 and 30% CO2. Patties in PVC and MAP were placed directly into coffin style display cases kept at 39°F for six days with constant fluorescent lighting. Master packages were placed in dark storage for six days then removed from dark storage and opened, and PVC trays inside the MP were placed into display cases for another six days. Instrumental color and trained panelists were utilized to determine color changes throughout the display period. Lipid oxidation, which causes off flavors and odors, contributes to the occurrence of discoloration and is the primary reason for antioxidant utilization. Lipid oxidation was measured on days 0, 3 and 6 for patties in PVC and MAP and on days 6, 9 and 12 for patties in MP. A trained taste panel was utilized to detect flavor differences in patties when cooked to 165°F by using a three-point scale.
Effects of dried distillers grains cube supplementation for steers grazing introduced
pastures on animal performance and forage production (page 8)
Justification and Actions: During the summer grazing season, steers grazing introduced forages are oftentimes provided protein and energy to improve animal performance. Dried distillers grains cubes (MasterHand Milling in Lexington, Nebraska) (DDGS), a by-product of ethanol production, has become a commonly utilized supplement for growing cattle due to the high energy and protein content with minimal starch. We hypothesized that DDGS supplementation for steers could improve animal performance and replace the need for N fertilizer on introduced pastures. Therefore, our objective was to evaluate the effects of supplementing DDGS and growth promoting implants for steers (n=149; BW = 524 ± 61.1 lb) grazing mixed tall fescue (Festuca arundinacea)/ bermudagrass (Cynodon dactylon) pastures (n=9 pastures, 18 ± 7.0 acres) in eastern Oklahoma from April 14 to Sept. 17 (n=155 days) on steer performance and forage production. Supplemental treatments (n=3 pastures/treatment) included 1) Fertilized control (FC), no supplementation on fertilized pastures (50 lb N/ acre); 2) Fertilized supplement (FS), supplemented DDGS at 2.7 lb/day prorated for 3-days/week feeding on fertilized pastures; and 3) supplement (S), supplemented DDGS at 0.75% BW/day prorated for 5-days/week feeding on unfertilized pastures. Steers were previously implanted during receiving with 40 mg trenbolone acetate and 8 mg estradiol (REV-G; Revalor G, Merck Animal Health). On July 7, steers in each pasture were randomly assigned to one of three re-implant treatments: 1) no re-implant; 2) REV-G; or 3) 200 mg progesterone and 20 mg estradiol (SYN-S; Synovex S, Zoetis Animal Health).
Profitability of supplementing dried distillers grains cubes to improve animal performance
and replace N fertilizer for steers grazing introduced pastures (page 10)
Justification and Actions: During the summer grazing season, steers grazing introduced pastures are oftentimes provided protein and energy to improve animal performance. Dried distillers grains cubes (DDGS) (MasterHand Milling in Lexington, Nebraska), a byAngusproduct of ethanol production, has become a commonly utilized supplement for growing cattle due to the high energy and protein content with minimal starch. However, it is important to determine if the additional supplementation is economically beneficial. We hypothesized that DDGS supplementation for grazing cattle could eliminate the need for N fertilizer without negative impacts on forage production and animal performance. This summary represents results from the first year of a two-year study with the objective to evaluate the profitability of supplementing DDGS to improve animal performance and replacing the use of N fertilizer (50 lb N/acre from urea). Steers (n=149; BW = 524 ± 61.1 lb) grazed mixed tall fescue (Festuca arundinacea)/bermudagrass (Cynodon dactylon) pastures (n=9 pastures, 18 ± 7.0 ac) from April 14 to Sept. 17 (n=155 d). Supplemental treatments were (n=3 pastures/treatment) included 1) fertilized control (FC), no supplementation on fertilized pastures; 2) fertilized supplement (FS), supplemented DDGS at 2.7 lb/day prorated for 3-days/week feeding on fertilized pastures; and 3) supplement (S), supplemented DDGS at 0.75% BW/day prorated for 5-days/week feeding on unfertilized pastures. The assumptions used in this analysis were based on actual costs of inputs for pasture management and the DDGS offered, as well as the five-year average Oklahoma auction market prices for 500-pound steers in April and 850-pound steers in October.
Evaluating supplementation programs for growing calves grazing Bermudagrass pastures
Introduction: Supplemental feeding is often warranted for growing calves grazing warm-season grass pastures during the summer. Dried distillers grains (DDGS) has many benefits for its use in supplements. For example, it has little starch, high energy and high bypass protein content. However, loose DDGS have not been used extensively in a pasture setting due to the potential loss of product from wind or mixture into the soil. Recently, an extruded DDGS cube has increased the flexibility of feeding DDGS in extensive pasture operations (MasterHand Milling in Lexington Nebraska). Operational time constraints limit a producer’s ability to manage supplement delivery, so a self-fed supplement offers advantages in limiting the time required for delivery of supplements to pastures. Thus, we aimed to determine gain response to self-fed (SF) or hand-fed (HF) summer supplementation programs at the University of Arkansas Livestock and Forestry Research Station on twenty 2-acre common Bermudagrass pastures stocked with five growing calves (two steers and three heifers) per pasture (initial BW ± SD = 554 ± 53.9 lbs). This research was a 2 × 2 + 1 factorial arrangement of treatments, including control (CON) – free choice mineral only; a DDGS hand-fed supplement 2.5 lbs/day DDGS cube supplement offered all summer (AS) or only late summer (LS); SF tub supplement (PVM Cattle Tub and Positive Feed Ltd. in Sealy, Texas) either AS or LS. This cooked molasses-based, tub-type supplement contained a minimum of 28% protein with 25% from non-protein nitrogen sources and at least 5% fat. Supplement costs (U.S. dollars) were $0.3718/lb for SF and $0.1675/lb for HF supplements.
Relationship between diet type, gas emissions and feed intake in cows (page 14)
Justification and Actions: Since direct measurement of intake in grazing cattle is not possible, methods to indirectly determine or estimate intake are needed. One method of indirect measurement is evaluation of greenhouse gas emissions. The GreenFeed Emission Monitoring System (GEM; C-Lock Inc., Rapid City, SD) collects multiple short-term breath measures and estimates emissions of carbon dioxide (CO2) and methane (CH4) and consumption of oxygen (O2) from cattle in a dry lot or pasture. The GEM collects gas emissions data by baiting cattle with a small amount of pelleted feed and then collecting air samples inside the head box while the animal consumes the feed. The strength of correlation between gas emissions data and intake is dependent on diet quality and feeding patterns. The objective of this study was to examine the effects of diet type on green-house gas emissions and dry matter intake (DMI). We used 42 mature, gestating registered Angus cows with a wide range in DMI EPD (-1.36 to 2.29). All cows had previously been genotyped using the AngusGS selection platform. Cows were randomly assigned to begin the study consuming 1 of 2 different diet types; grass hay only (H) or 35% hay blended with 64% concentrate feeds (DM basis) in a mixed ration (C). Thus, two diet sequences were established; HC = hay only followed by the mixed ration and CH = mixed ration followed by hay. The cows were adapted to the diet and the Smart-Feed individual intake units for 14 days followed by a minimum of 45 days of intake data collection for each period. Cows were exposed to the GreenFeed Emission Monitoring (GEM) system for no less than 9 days during each period. Only cows with a minimum of 20 total > 3-minute visits to the GEM were included in the data set.
Dried distillers grains cube as a supplement for steers grazing mixed grass prairie
in northwest Oklahoma (page 16)
Justification and Actions: Weight gain of stocker cattle can be limited by protein availability as forage quality declines during late summer. The Oklahoma SuperGold program was designed to deliver 2.5 pounds of a mid-protein (25% crude protein) feed, providing supplemental protein, energy, minerals and an ionophore. Increased costs of production and land are driving producers to intensify production due to significant economic pressures to maximize production per acre. This practice can lead to over grazing and deteriorating range conditions. Replacing a portion of the daily forage needs with supplemental concentrate feed could offset nutrient deficiencies, allow for increased stocking density and avoid overgrazing.
We are researching the effects of an extruded distillers cube (MasterHand Milling in Lexington, Nebraska) supplemented to growing steers grazing mixed grass prairie in western Oklahoma. This research was conducted at the USDA-Agricultural Research Service’s Southern Plains Experimental Range [SPER] near Fort Supply, Oklahoma, in Harper County. Our hypothesis is that stocking rates can be increased by replacing a fraction of the daily forage intake with supplemental DDGS cubes while avoiding negative impacts on animal performance and native range condition. Three treatments were initiated at Fort Supply. Treatments at SPER were: 1) negative control, no supplement; 2) positive control, supplemented with DDGS cubes 2 lbs/ steer fed on alternate days (4.7 lbs/feeding) during late summer only; and 3) high supplement, 1/3 increase in stocking rate, 0.75% BW supplemental DDGS cubes throughout the grazing season (April to September or whatever).
Using a dried distillers grain cube as a supplement for steers grazing mixed grass
prairie in western Oklahoma (page 18)
Justification and Actions: Dried distillers 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 advantages in using DDGS in a stocker cattle 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. We are researching the effects of an extruded distillers cube (MasterHand Milling, Lexington, Nebraska) 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 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. In the summer of 2020, the second year of a grazing trial was conducted at the Marvin Klemme Range Research Station. This trial was to test the effects of supplementation with an extruded 100% DDGS cube. For this experiment, 140 crossbred steers were separated into two supplementation treatments randomly allotted to six pastures (n = 3 pastures/ treatment):
- Positive control supplemented at a daily rate of 2.5 lbs/steer prorated for feeding three days per week (5.8 lbs/steer each feeding) during the last half of the grazing season from July through September with a stocking rate of 6 acres/steer.
- High supplement, supplemented at 0.75% of BW throughout the grazing season (from May through September) with a 33% increase in stocking rate (4 acres/steer).
Using whole cottonseed to replace dried distillers grains and prairie hay in finishing
rations balanced for physically effective neutral detergent fiber (page 20)
Justification and Actions: Dried distiller grains (DDGS) are a readily available and competitively priced byproduct of ethanol production in the Midwest and Great Plains and have been used extensively in finishing cattle diets in recent years. Cotton is a popular commodity in the southern U.S., and cotton byproducts are consistently available in the southern U. S. and have the potential to be an effective source of protein, fat and roughage within cattle finishing rations. The objective of this experiment was to determine if replacing hay and DDGS with whole cottonseed impacts the performance and carcass characteristics of feedlot cattle in diets. At the Willard Sparks Beef Research Center in Stillwater, Oklahoma, crossbred heifers (n=103) and steers (n=104) were allocated to 12 pens in a randomized complete block design (six pens per treatment; three pens of heifers and three pens of steers) with sex and weight serving as blocking factors. Pens were randomly allocated to one of two experimental diets. Treatments consisted of the control diet (CON) of prairie hay, dry distiller’s grains plus solubles, dry-rolled corn and liquid supplement and the whole cotton-seed diet (CTN) of whole cottonseed, dry-rolled corn and molasses. Both diets contained a dry vitamin and mineral supplement and urea at the same inclusion rate. All cattle received a common receiving ration for four days after arrival, consisting of wet corn-gluten feed (sweet bran), prairie hay, dry-rolled corn and a dry vitamin and mineral supplement, followed by a 28-day transition period using a step-up ration approach based on the final experimental diet (CON or CTN) with seven days per step. Body weights (BW) were collected every 14 days until day 56. After day 56, BW were collected every 28 days. Due to varybehavioraling weights across blocks, cattle were shipped to harvest in three different harvest groups. Thirty-one days prior to shipping to harvest, ractopamine hydrochloride (Optiflexx 45, Elanco Animal Health in Greenfield, Illinois) was added to the diet.
Effects of virtual fencing on cortisol concentrations and behavior of beef cattle
Justification and Actions: Virtual fencing is a new alternative to conventional fencing in the livestock industry. However, due to the novelty of virtual fencing, it has not been extensively used in a rotational grazing format and its effects on livestock are unknown. This research was conducted at the Oklahoma State University Bluestem Research Range near Stillwater, Oklahoma, in order to evaluate the effects of virtual fencing on stress and behavior in grazing beef cattle. Two experiments were conducted in the fall of 2020 in partnership with VENCE (www. vence.io). In both experiments, cattle were contained by either physical, two-strand electric fencing or by use of a proprietary, GPS-based virtual fencing collar, with no physical interior fencing. In both studies, hair from the tail switch was collected at the end of the experiment and analyzed for cortisol concentration to measure the accumulated stress experienced by the cattle. Additionally, a subset of cattle was fitted with pedometers to measure responses. In the initial pilot experiment, 55 heifers (BW= 693 ± 66.0 lbs) were grazed for 28 days in either one physically fenced pasture (PF, n=24) or one virtually fenced pasture (VF, n=31). In the second experiment, 59 mature cows and heifers (BW=1,064 ± 184.8 lbs) were grazed for 56 days in one of two physically fenced (PF, n=15 and 15 animals) or one of two virtually-fenced pastures (VF, n=15 and 14 animals; 4 pastures in total). In the second experiment, blood samples were also collected and NEFA (nonesterified fatty acids, an indicator of nutritional status) and lactate (also an indicator of nutritional status) were quantified in plasma.
Vaccination strategies for preconditioning beef calves (page 24)
Justification and Actions: Cattle producers have adopted multiple timing strategies and viral components when administering vaccines to pre- and post-weaned calves. The Oklahoma Beef Management and Marketing Survey indicated that 66% of the beef cow herds have no defined calving season. This may increase the use of killed-virus (KV) vaccines, which are often used without the booster vaccination required by the label directions. The use of KV vaccines at branding is thought to be used to avoid potential negative effects associated with modified-live viral (MLV) vaccines on bred cows. However, this practice may provide limited protection against bovine respiratory disease (BRD) for the calf. The Oklahoma Quality Beef Network (OQBN) is a health management and value-added marketing program. For certification in the OQBN, three vaccination protocols are available, each requiring the use of MLV vaccine products. The study’s objective was to examine the effects of vaccine type and timing on animal performance and immune response pre- and post-weaning of protocol strategies utilized most by OQBN participants. Research was conducted at the Range Cow Research Center, South Range Unit located near Stillwater, Oklahoma. A total of 151 Angus, Angus x Hereford, or Angus x Charolais calves were randomly assigned to one of three health protocols stratified by breed of sire, sex and date of birth. Vaccination treatments were 1) KV/MLV – mul-tivalent KV BRD vaccine administered on day 0 (3 to 4 months of age) and revaccination with a 5-way MLV vaccine at weaning on day 127; 2) MLV/MLV – 5-way MLV vaccine on day 0 (3 to 4 months of age) and at weaning on day 127; or 3) WEAN – 5-way MLV vac-cine at weaning on day 127 and 2-weeks post-weaning on day 140. Treatments 2 (MLV/MLV) and 3 (WEAN) correspond with the OQBN vaccination protocols 1 and 3, respectively. Virus specific antibody titer data was determined using serum-neutralization from serum collected on day 0, 127, 140, 154, 168 and 182. Serum collected on day 0 was used as a baseline measure. Antibody titers, body weight and average daily gain variables were evaluated following vaccination.
Relationship of retained energy in lactating beef cows to maintenance energy requirement
and dry period voluntary feed intake (page 26)
Justification and Actions: Over the last 30 years, much progress has been made in the beef industry with increasing growth rate and carcass weight. However, little research has been conducted to determine the influence of continued aggressive selection for production traits on the cost to maintain a beef cow. In studies conducted 30 to 40 years ago, breeds that had greater genetic capacity for growth and milk and mature weight also tended to have greater maintenance energy requirements. Few studies are available investigating the influence of production potential within a breed. The objective of this experiment was to determine the relationship between recovered energy (cow weight gain and milk production) in Angus cows to maintenance energy requirements and to dry period voluntary intake of grass hay. This research was conducted at the Range Cow Research Center near Stillwater, Oklahoma. Twenty-four mature fall-calving Angus cows were used in two consecutive experiments. In the first experiment, cow-calf pairs were individually fed for an 82-day period. Feed intake was adjusted every other week to ensure minimal weight and body condition change by the end of the experimental period. Recovered energy was calculated as the total of maternal tissue energy change (weight gain or loss) plus milk recovered energy (milk yield plus milk composition). From this information, maintenance energy requirements were calculated for each cow. After calves were weaned, a voluntary feed intake study was conducted to determine the influence of total recovered energy during lactation and lactation maintenance energy requirement on voluntary intake of a low-quality grass hay diet.