Beef Science Commons^™

Improving Genomic Prediction For Feed Efficiency Traits In Beef Cattle Using Microbiome As An Intermediate Omics, Egodage Bhagya Sewwandi Samarakoon

Department of Animal Science: Dissertations, Theses, and Student Research

Feed efficiency traits, including feed conversion ratio (FCR), average daily gain (ADG), and average daily dry matter intake (ADDMI), are economically important in beef cattle production. Emerging evidence suggests that host genetics influences feed efficiency traits through the microbiome. This study evaluates the integration of microbiome data as an intermediate layer in the Neural Network Mixed Model (NNMM), which hierarchically models genotype–microbiome–phenotype relationships as a unified regulatory network to improve genomic prediction accuracy. To reduce the computational burden of NNMM, microbiome features dimension were reduced using principal component analysis (PCA) and direct feature selection of top-ranked open reading frames (ORFs) …

The Detection Of Morbidity Using A Remote Sensing Ear Tag On Newly Received Steers And Feedlot Performance And The Effects Of Feeding Experior And Optaflexx On Carcass Characteristics And Meat Tenderness In Beef Steers, Lauryn O. Smidt

Department of Animal Science: Dissertations, Theses, and Student Research

Two experiments were conducted to evaluate the effects of remote sensing health technology and growth-promoting feed additives on feedlot cattle performance, health outcomes, and carcass characteristics. In the first study, 638 crossbred steers (initial BW = 270 kg; SD = 18.6 kg) were used in a randomized block design to assess the effectiveness of a remote sensing ear tag (RST; HerdDogg, Seward, Nebraska) versus conventional pen-rider observation (PR) for detecting morbidity during a 35-d receiving period and subsequent 180-d finishing period. No differences were detected between PR and TAG for ending BW, average daily gain (ADG), dry matter intake (DMI), …

Carcass Mass And Cooling Dynamics As Determinants Of Beef Color, Tenderness, And Dark-Cutting Risk, Grace C. Johnson

Department of Animal Science: Dissertations, Theses, and Student Research

Discoloration in beef has important implications to the beef industry. Dark-cutting (DC) beef remains one of the most economically significant color defects; however, industry prevalence has only marginally declined (≈ 0.1%) despite mitigation efforts. This lack of improvement largely stems from research focused on pre-harvest stress and glycogen depletion leading to dark, firm, and dry (DFD) beef. However, not all darkcutting beef originates from DFD phenotypes. Atypical dark-cutting (ATDC) phenotypes have recently been observed and do not exhibit the classic metabolic indicators of DFD. This trend coincides with steadily increasing carcass weights in the beef industry and raises the possibility …

Lipid Deposition In Beef Cattle, Kyra L. Elliott

Department of Animal Science: Dissertations, Theses, and Student Research

Both the amount and types of lipid deposition in beef cattle are key determinants of carcass value and meat quality. Amounts of intramuscular, subcutaneous, and visceral fat influence carcass grading outcomes, palatability, and composition traits that are important to beef producers as well as consumers. The objectives of this thesis were to: 1) compare beef grading camera estimates of intramuscular fat to amounts of chemically extractable lipid, 2) characterize the lipidomes of beef intramuscular fat, subcutaneous fat, and lean muscle using shotgun lipidomics, and 3) identify and characterize a novel genetic variant in cattle that may have important implications for …

Evaluation Of Maternal Bovine Appeasing Substance Administration And Feed Access Time On Finishing Cattle Performance, Behavior, And Carcass Characteristics, Carsten L. Loseke

Department of Animal Science: Dissertations, Theses, and Student Research

Novel products and bunk management techniques may significantly influence economically relevant performance metrics of feedlot cattle. The objective of the first experiment was to evaluate maternal Bovine Appeasing Substance (mBAS) administration on performance, carcass, health, and cortisol outcomes of yearling steers. Steers (n = 1,754, initial BW = 423 kg, SD = 25 kg) were received and assigned to pens for treatment allocation. Steers received either 10 mL of the mBAS or a mineral oil placebo at initial processing and reimplant. Hair samples were collected from a subset (n = 4 steers/pen) on d 0 and d 14. …

Application Of High-Pressure Processing To Improve The Color Of Dark Beef, Kara Ann Reynolds

Department of Animal Science: Dissertations, Theses, and Student Research

Deviation of beef from the bright cherry-red color preferred by consumers is often discounted or discarded at retail, resulting in substantial annual economic loss to the beef industry. One such deviation is dark cutting beef, which is characterized by a darker lean appearance that is undesirable to consumers and often rejected. Similarly, beef from mature cattle tends to exhibit a darker surface color, which can also reduce consumer acceptability. High-Pressure processing (HPP) has been investigated as a strategy to improve the color of dark cutting beef. Previous studies have focused on identifying pressure levels and holding times that optimize color …

Evaluating Management Strategies And Technology To Improve Grazing Efficiency, Thomas E. Aquino

Department of Animal Science: Dissertations, Theses, and Student Research

Increasing land costs and labor constraints continue to challenge beef producers. More intensive practices can increase harvest efficiency; however, many producers are deterred from implementing them due to increased labor and management considerations. Virtual fencing (VF) may provide a reduced labor alternative to traditional fencing for managing intensive grazing. This dissertation evaluated management strategies and VF technology to improve grazing efficiency of stocker cattle systems. In Experiment 1, VF was used to effectively manage groups of steers grazing in adjacent paddocks separated by only virtual boundaries. There was no difference in VF containment (99%) when steers were grazing co-fenced, with …

Evaluation Of Palm Oil As An Ingredient In Finishing Beef Cattle Diets On Performance, Carcass Characteristics, And Meat Quality, And The Composition Of Spayed Heifers To Intact Heifers Fed Melengestrol Acetate On Feedlot Performance And Carcass Characteristics, Tate S. Johnson

Department of Animal Science: Dissertations, Theses, and Student Research

Heifers represent a large proportion of cattle placed in feedlots, making pregnancy management an important consideration for maintaining performance and carcass value. Melengestrol acetate (MGA) is commonly included in feedlot diets to suppress estrus and prevent pregnancy in intact heifers during the finishing period. Alternatively, spaying has historically been utilized as a management practice to allow heifers to graze alongside breeding cattle without the risk of pregnancy. Despite its historical use, there is limited contemporary research comparing the growth performance and carcass characteristics of spayed heifers with intact heifers managed with MGA under modern feedlot conditions. Therefore, a commercial study …

Exploratory Evaluation Of Handler Performance And Processing-Related Outcomes During Cattle Handling, Morgan Marquardt

Department of Animal Science: Dissertations, Theses, and Student Research

Animals have several critical roles in society, including the production of food and fiber, and companionship. Contact with animals has been shown to benefit human physical and mental health, yet little research has investigated the impact that humans have on animals. Handler skill may considerably affect the extent to which humans influence animal health and wellbeing, and this may be a critical consideration for animal agriculture. Objective assessment of cattle handler skill has received limited attention in the scientific literature, despite its importance to human safety and animal welfare. When compared to less skilled handlers, highly skilled cattle handlers may …

Associations Of Variation In Mtdna With Feed Efficiency In Beef Cattle And The Evaluation Of Transcriptomic Changes In Fetal Kidney Due To Hydrallantois, Lauren Elizabeth Seier

Department of Animal Science: Dissertations, Theses, and Student Research

Project 1 focused on the central role that mitochondria play in ATP production, highlighting that variation within the mtDNA may influence feed efficiency. Variation in the mitochondrial genome was uncovered, and associations with feed efficiency in beef cattle were identified. Growth and feed intake phenotypes, as well as low-pass sequencing, were collected on beef steers across two populations. Protein coding variants were identified and used to classify animals into mitochondrial haplotypes. A linear mixed model was employed, which detected a significant association between mitochondrial haplotype and DMI. A significant haplotype with a variant in Complex I was associated with reduced …

Evaluation Of Two Different Sweet Bran Products On Beef Cattle Digestion Characteristics And A Review Of Ramp As An Alternative Step-Up Program, Emily K. Hoefling

Department of Animal Science: Dissertations, Theses, and Student Research

Two Sweet Bran products were evaluated at 13%, 18%, and 23% inclusion of the diet on total tract digestibility and rumen fermentation parameters. Seven ruminally cannulated, heifers were used in a 6 x 7 row-column design with 21-d periods consisting of 16-d adaptation period followed by a 5-d collection. Dietary treatments were designed in a 2 x 3 factorial arrangement with 6 periods. Factors included two Sweet Bran products that differed in particle size (Sweet Bran-SP; GMD = 1.79 mm or Sweet Bran-LP; GMD = 2.51 mm) and three dietary inclusion (13%, 18%, or 23% of diet dry matter). The …

Using High-Pressure Processing To Improve The Quality Of Dark-Cutting Beef, Ashley A. Hahn

Department of Animal Science: Dissertations, Theses, and Student Research

Previous studies have shown high-pressure processing (HPP) can be utilized to improve lean color of dark-cutting beef color by increasing the lightness and redness of steaks. However, the optimal parameters of length of time product is held under pressure and at which pressure must be applied have yet to be fully defined. Furthermore, the impact of HPP on color labile muscles in dark-cutting beef are currently unknown. Therefore, two studies were designed and specific efforts were focused on first defining optimal parameters for color stable muscles, followed by determining the effect of HPP on dark-cutting color labile muscles.

In the …

Relationship Between Host Genomics And Microbiomics In Beef Cattle, Andrew D. Lakamp

Department of Animal Science: Dissertations, Theses, and Student Research

As sequencing technology becomes more affordable and throughput increases, microbiome information is becoming more readily available. For beef cattle selection, microbial information has a variety of uses including being a target for genetic prediction or used as a means to explicitly describe additional phenotypic variability in other traits.

Infectious bovine keratoconjunctivitis (IBK), commonly known as pinkeye, is a disease that infects the ocular surface and surrounding tissue which is an animal health and producer economic concern. Vaccinations have shown to have variable effectiveness, while limited genetics studies have suggested that direct genetic selection for resistance would be slow. Therefore, an …

Heat Stress Changes The Bovine Methylome And Transcriptome And Investigation Of Two Novel Genetic Defects In Cattle, Rachel Renae Reith

Department of Animal Science: Dissertations, Theses, and Student Research

Heat stress is a major concern for livestock producers due to its negative impact on animal health and productivity. Heat stress does so by altering expression of genes through different regulatory mechanisms such as DNA methylation. Understanding how heat stress alters gene expression will help elucidate the genetic basis of physiological changes as well as identify targets for possible heat stress mitigation. The purpose of the first study was to understand how heat stress alters the adipose and skeletal muscle transcriptomes in zilpaterol-fed Brahman, as zilpaterol improves muscle growth and may mitigate the effects of heat stress. Differential expression and …

Impact Of Strategic Postweaning Supplementation On March- And May-Born Yearling Range Heifer And Calf Growth And Performance In The Nebraska Sandhills, Josie Nicole Crouch

Department of Animal Science: Dissertations, Theses, and Student Research

Three experiments were conducted at the Gudmundsen Sandhills laboratory near Whitman, Nebraska. Experiment 1, a retrospective regression analysis, evaluated the impact of heifer percentage of mature body weight (BW) at breeding on heifer performance, subsequent pregnancy rates, and calf production. Overall pregnancy rates were greater (P < 0.01) for heifers at 60 to 70% of mature BW than 50 to 55%, with no differences in pregnancy rates (P ≥ 0.15) after 2-years of age. Heifers at 50 to 60% of mature BW had a greater (P = 0.05) proportion give birth in the first 21-d. A higher percentage of mature BW at breeding resulted in greater (P < 0.01) BW at birth and weaning for offspring.

Experiments 2 and 3 were 3-year studies that evaluated the impact …

Artificial Insemination And Fetal Programming In Beef Production Systems, Dempster M. Christenson

Department of Animal Science: Dissertations, Theses, and Student Research

Pregnancy to artificial insemination and late gestation fetal programming of the next calf crop are central to genetic development, reproductive longevity, calf crop productivity, and efficiency of cow/calf ranching. The purposes of this research are to find methods to improve pregnancy rate to artificial insemination, the growth and reproductive health of pregnant heifers, and the productivity of their offspring. In the first of four studies we found that extending the period of progesterone administration in an estrus synchronization protocol did not significantly hasten estrus response or increase pregnancy rate to artificial insemination, but timing of estrus within the melengestrol acetate …

Predicting Body Weight Of Cattle And Nutrient Digestion Of Individual Sweet Bran Components To Improve Beef Cattle Production Efficiency, Dalton J. Anderson

Department of Animal Science: Dissertations, Theses, and Student Research

Efficiency is of high importance to beef cattle producers to ensure that beef cattle are being raised without unnecessary resource use. Two separate experiments were conducted to evaluate potential strategies to improve efficiency in beef cattle production. A metabolism study was conducted to evaluate digestion parameters of individual Sweet Bran components. The objective was to determine the effects of diet components on nutrient digestion and rumen fermentation parameters. The individual components of Sweet Bran (Corn bran, solvent-extracted germ meal, and corn steep liquor) were included at 40% diet dry matter (DM) in a steam-flaked corn (SFC) based diet. A SFC-based …

Investigation Of Breeding Objectives And Indexes-In-Retrospect, Hunter F. Valasek

Department of Animal Science: Dissertations, Theses, and Student Research

This thesis presents two projects that investigate the impacts of breeding objectives and indexes-in-retrospect within the beef cattle industry. The first project synthesized how changes due to planning horizon, breeding system, and sale endpoint in the economic breeding goal of cattle influence the relative emphasis of traits as well as the re-ranking of selection candidates. A total of three breeding systems that represent straightbred and crossbred cattle were used along with six planning horizons (2, 5, 10, 20, 30, and 50 yrs.) for both a weaning and slaughter point of sale. The combination of these different breeding objective attributes resulted …

The Evaluation Of Feed Additives On Reducing Enteric Methane Production From Cattle, Reba L. Colin

Department of Animal Science: Dissertations, Theses, and Student Research

Environmental sustainability can be positively impacted by the inclusion of feed additives to reduce enteric methane production from cattle. Methane production can be affected by feed additives that either alter the rumen environment or act as methanogenesis inhibitors. A reduction in methane from cattle can contribute to meeting carbon neutrality.

A metabolism study was conducted to evaluate Alga 1.0, a product containing bromoform, fed to cattle to evaluate the effects on gas emissions. Treatments were (0, 69, or 103 g/d Alga 1.0) fed in a corn-based diet. Headbox-style indirect calorimeters were used to measure gas emissions. Feeding Alga 1.0 linearly …

The Impact Of Silage Inclusion In Diets With Different Corn Processing And The Effect Of Natural And Conventional Feeding Programs On Finishing Cattle Performance, Jessica L. Miller

Department of Animal Science: Dissertations, Theses, and Student Research

A finishing experiment was conducted to determine the effects of natural and conventional feeding programs on finishing performance of steers and heifers. Factors were conventional and natural feeding programs in steers and heifers. Cattle assigned to the conventional program were fed diets that contained Rumensin (Elanco Animal Health), Tylan (Elanco Animal Health), MGA (Zoetis), and received growth promoting implants whereas cattle in the natural program received neither. Compared to natural fed cattle, G:F was improved by 15.5% when heifers were fed in a conventional program (P < 0.01) and 23.8% when steers were fed in a conventional program (P < 0.01). The incorporation of implants and feed additives within the finishing period increased …

Forages And Technology Management In Growing And Finishing Beef Cattle Systems, Kelton Cole Adair

Department of Animal Science: Dissertations, Theses, and Student Research

A systems study evaluated the effects of an implant [25.7 mg estradiol (Compudose; Elanco Animal Health)] at two rates of gain (LOW: 0.45 kg/d and HIGH: 0.9 kg/d) applied during the winter backgrounding phase in drylot and winter grazing systems and its effects on subsequent phases of production. HIGH supplementation with an implant during the winter backgrounding phase in the drylot system yielded the greatest ending body weight (EBW) during the summer backgrounding phase (P = 0.04). LOW supplementation, without an implant, improved summer backgrounding average daily gain (ADG; P = 0.05) while achieving similar carcass adjusted final body …

Dry-Aged Beef Flavor Development, And The Effect Of High Levels Of Vitamin-E On Beef Color Stability, Nicolas Herrera

Department of Animal Science: Dissertations, Theses, and Student Research

Palatability and consumer purchasing are essential factors of fresh meat. To meet consumer expectations during purchasing and consumption, fresh beef must maintain desirable cherry-red color at retail and achieve desirable cooked flavor. Dry-aged beef popularity has grown, and identifying methods to ensure quality dry-aged meat is necessary to maintain demand. To understand dry-aged palatability, this dissertation addressed effects of moisture loss and aging time, fundamental factors of dry-aged beef, using bone-in and boneless strip loins. Study two investigated flavor development using cookery methods and internal temperatures in boneless and bone-in dry-aged beef. In study one, increased dry-aging time (creation effect) …

Consequences Of Cow–Calf Production With Limited Perennial Forage Grazing, Hannah Fae Speer

Department of Animal Science: Dissertations, Theses, and Student Research

Conversion of perennial grasslands to cropland and rising land prices prompts a need to evaluate alternative beef cow-calf production systems. A 3-yr study was conducted comparing beef cow-calf performance between two August-calving cow systems: perennial forage and corn residue grazing; or summer drylot, fall grazing of late-summer-planted cover crop, and corn residue grazing. Cow body condition score differed between systems, but condition of cows in both systems never fell below adequate. There were no differences in pregnancy rates between systems. Calf weaning weights differed between systems each year; differences are attributed to feedstuff quantity, quality, and type available to calves …

Effect Of Supplementation Prior To Artificial Insemination And During Gestation In Beef Females, Landon Folsom Tadich

Department of Animal Science: Dissertations, Theses, and Student Research

Objectives of Experiment 1 was to evaluate the impact of increased energy prior to AI on BW, ADG, and reproductive efficiency in heifers developed on range or in a dry lot. During the winter development period (131 ± 3.5 d/yr) heifers (n = 100/yr) were assigned to either upland range (RANGE) or fed a dry lot diet in two pens that either remained constant (DLLO) or increased in energy prior to AI (DLHI). Heifers developed on RANGE grazed upland winter range until 38 d prior to AI where they then received the DLLO diet. Pre-breeding BW was greater ( …

Methods To Reduce Nitrogen And Carbon Losses From Finishing Beef Cattle, Hanna K. Cronk

Department of Animal Science: Dissertations, Theses, and Student Research

A finishing experiment evaluated the effect of incremental supplemental rumen-protected lysine on beef cattle performance. All cattle were fed the same diet of high moisture corn, dried rolled corn, modified distillers grains plus solubles, corn silage, and supplement with inclusion levels of lysine ranging from 0 to 7 grams/day, in 1 g increments. Dry matter intake (P ≤ 0.04) and ADG (P ≤ 0.04) decreased linearly as supplemental lysine increased in the diet with no effect on final carcass adjusted feed efficiency (P ≥ 0.34). In the initial 64 days of the experiment, increasing lysine in the …

Impacts Of Feeding Biochar To Beef Cattle On Greenhouse Gas Emissions And Performance And Characterizing Yearling Steers Grazing Smooth Bromegrass Pasture Using Gps, Holly A. Heil

Department of Animal Science: Dissertations, Theses, and Student Research

As global warming continues to rise, the pressure and growing demand for sustainable animal production is increasing. Livestock naturally produce greenhouse gas emissions through enteric fermentation. Dietary manipulation strategies have been sought out to decrease emissions in ruminants using feed additives.

Two independent finishing feedlot experiments evaluated two types of biochar and its effects on animal performance, carcass characteristics and greenhouse gas emissions. Experiment 1 utilized pistachio shell biochar and experiment 2 utilized biochar sourced from ponderosa pine wood waste, both types included at 1% of the diet DM. The addition of biochar to the diet did not impact animal …

Variance Component Estimates For Growth Traits In Beef Cattle Using Selected Variants From Imputed Low-Pass Sequence Data, Chad A. Russell

Department of Animal Science: Dissertations, Theses, and Student Research

A beef cattle population (n = 2,343) was used to assess the impact of variants identified from imputed low-pass sequence (LPS) on the estimation of variance components and genetic parameters of birth weight (BWT) and post weaning gain (PWG). Variants were selected based on functional impact and were partitioned into four groups (Low, Modifier, Moderate, High) based on predicted functional consequences and re-partitioned based on consequence of mutation, such as missense and untranslated region variants, into six groups (G1-G6). Each subset was used to construct a genomic relationship matrix (GRM) for univariate animal models. Multiple analyses were conducted to …

Investigating Bacterial Community Composition And Antimicrobial Resistance Genes In Beef Cattle, Arena E. See

Department of Animal Science: Dissertations, Theses, and Student Research

While antibiotics have been critical over the last decade for curbing infectious diseases, they have contributed to the rise of antimicrobial resistance (AMR). Infections resulting from antimicrobial-resistant pathogens are correlated with severe morbidity, mortality, and healthcare costs. With the increasing concerns regarding AMR and its emergence, it is paramount to understand not only the effects of antibiotics on microbial community and diversity, but also to develop a novel tool that gives us a better understanding of the spread and functional traits of AMR genes.

To this end, rumen, fecal, and pen surface samples were collected from 72 animals at United …

The Impact Of Steam-Flaked Rye Replacing Steam-Flaked Corn On Performance And Carcass Characteristics Of Yearling Steers And The Effect Of Exogenous Megasphaera Elsdenii Administration Techniques On Ruminal Fermentation And Blood Parameters In An Acidosis Challenge Model, Samantha K. Wagner

Department of Animal Science: Dissertations, Theses, and Student Research

A feedlot study was conducted to evaluate the effects of replacing steam-flaked corn (SFC) with steam-flaked rye (SFR) in the diets of yearling steers (Exp. 1). A separate study was conducted to evaluate the effects of three different administration techniques of Megasphaera elsdenii NCIMB 41125 on rumen fermentation and blood parameters in an acidosis challenge model (Exp. 2). In Exp. 1, SFC was replaced with SFR to create four different treatments, each differing in the ratio of SFC:SFR. The four treatments were 0:100, 25:75, 50:50, and 100:0 SFR:SFC (as a percentage of the grain inclusion). Increasing inclusions of SFR resulted …

Evaluation Of Corn Processing Method And Sweet Bran Inclusion On Beef Cattle Performance And Nutrient Digestion And Individual Sweet Bran Components On Nutrient Digestion, Rebecca L. Sjostrand

Department of Animal Science: Dissertations, Theses, and Student Research

One feedlot trial (Exp. 1) and one digestion trial (Exp. 2) were conducted to evaluate the interaction of corn processing method and Sweet Bran inclusion on nutrient digestion, ruminal fermentation parameters, and feedlot performance. In Exp. 1 when no Sweet Bran was fed, cattle fed steam-flaked corn (SFC) had greater ADG, HCW and a 12.4% improvement in feed efficiency compared to cattle fed a high-moisture corn/ dry-rolled corn (HMC/DRC) blend. However, as Sweet Bran increased in the diet to 40%, cattle fed HMC/DRC had greater improvements in ADG and HCW than cattle fed SFC resulting in similar performance at 40% …