Meat Science Commons^™

144 Effect Of Antral Follicle Count In Beef Heifers On In Vitro Fertilization/Production, C. C. Chase Jr., R. A. Freeland, A. K. Mcneel, E. C. Wright-Johnson, G. A. Perry, S. C. Tenley, J. R. Wood, A. S. Cupp, J. L. Vallet, J. R. Miles

Department of Animal Science: Faculty Publications

Our objective has been to compare the IVF and in vitro production (IVP) of embryos from low and high antral follicle count (AFC) heifers. This is the fourth year of the study with years 1 to 3 reported individually. For this report, we add data for the fourth year and present a combined analysis (years 1 to 4) for the first time. Each year, AFC was determined on ~120 Angus heifers using transrectal ultrasonography. Ten heifers with the lowest AFC and 10 heifers with the highest AFC and all with evidence of oestrous cyclicity were synchronized with two 5-mL injections …

Medical Subject Heading (Mesh) Annotations Illuminate Maize Genetics And Evolution, Timothy M. Beissinger, Gota Morota

Department of Animal Science: Faculty Publications

Background: High-density marker panels and/or whole-genome sequencing, coupled with advanced phenotyping pipelines and sophisticated statistical methods, have dramatically increased our ability to generate lists of candidate genes or regions that are putatively associated with phenotypes or processes of interest. However, the speed with which we can validate genes, or even make reasonable biological interpretations about the principles underlying them, has not kept pace. A promising approach that runs parallel to explicitly validating individual genes is analyzing a set of genes together and assessing the biological similarities among them. This is often achieved via gene ontology analysis, a powerful tool that …

Production Of A Gonadotropin-Releasing Hormone 2 Receptor Knockdown (Gnrhr2 Kd) Swine Line, A. T. Desaulniers, R. A. Hou, G. A. Mills, C. A. Lents, Brett R. White

Department of Animal Science: Faculty Publications

Swine are the only livestock species that produce both the second mammalian isoform of gonadotropin-releasing hormone (GNRH2) and its receptor (GNRHR2). Previously, we reported that GNRH2 and GNRHR2 mediate LH-independent testosterone secretion from porcine testes. To further explore this ligand-receptor complex, a pig model with reduced GNRHR2 expression was developed. Small hairpin RNA sequences targeting porcine GNRHR2 were subcloned into a lentiviral-based vector, lentiviral particles were generated and microinjected into the perivitelline space of zygotes, and embryos were transferred into a recipient. One GNRHR2 knockdown (KD) female was born that subsequently produced 80 piglets from 6 litters with 46 hemizygous …

Physically Adjusted Neutral Detergent Fiber System For Lactating Dairy Cow Rations. I: Deriving Equations That Identify Factors That Influence Effectiveness Of Fiber, Robin R. White, Mary Beth Hou, Jeffrey L. Firkins, Paul J. Kononoff

Department of Animal Science: Faculty Publications

Physically effective neutral detergent fiber (peNDF) is the fraction of neutral detergent fiber (NDF) that stimulates chewing activity and contributes to the floating mat of large particles in the rumen. Multiplying dietary NDF by particle size has been used as an estimate of peNDF. In re-evaluating the concept of peNDF, we compared the use of peNDF as dietary NDF × particle size with the use of individual NDF and particle size descriptors (physically adjusted NDF; paNDF) when used with other physical and chemical diet descriptors to predict dry matter (DM) intake (DMI), rumination time, and ruminal pH in lactating dairy …

Expression Of Cytokine Genes And Receptors In White Blood Cells Associated With Divergent Body Weight Gain In Beef Steers, Amanda K. Lindholm-Perry, Virginia M. Cederberg, Jeremy R. Miles, Andrew P. Foote

Department of Animal Science: Faculty Publications

Previous work examining the transcriptome of steer tissue samples from animals with divergent gain have shown a relationship with the expression of genes with functions in immune and inflammatory pathways. The process of mounting an immune or inflammatory response is energetically expensive and variation in cytokine responses may affect cattle production traits. In addition, a previous study has identified variation in the transcript abundance of numerous genes, including the cytokine gene IL6ST, in the circulating white blood cells of pigs associated with high and low residual feed intake (RFI) lines. The aim of this study was to determine whether …

Economic Selection Index Development For Beefmaster Cattle I: Terminal Breeding Objective, Kathleen P. Ochsner, M. D. Macneil, Matthew L. Spangler

Department of Animal Science: Faculty Publications

The objective of this study was to develop an economic selection index for Beefmaster cattle in a terminal production system where bulls are mated to mature cows with all resulting progeny harvested. National average prices from 2010 to 2014 were used to establish income and expenses for the system. Phenotypic and genetic parameter values among the selection criteria and goal traits were obtained from literature. Economic values were estimated by simulating 100,000 animals and approximating the partial derivatives of the profit function by perturbing traits one at a time, by 1 unit, while holding the other traits constant at their …

The Impact Of Training Strategies On The Accuracy Of Genomic Predictors In United States Red Angus Cattle, J. Lee, Stephen D. Kachman, Matthew L. Spangler

Department of Animal Science: Faculty Publications

Genomic selection (GS) has become an integral part of genetic evaluation methodology and has been applied to all major livestock species, including beef and dairy cattle, pigs, and chickens. Significant contributions in increased accuracy of selection decisions have been clearly illustrated in dairy cattle after practical application of GS. In the majority of U.S. beef cattle breeds, similar efforts have also been made to increase the accuracy of genetic merit estimates through the inclusion of genomic information into routine genetic evaluations using a variety of methods. However, prediction accuracies can vary relative to panel density, the number of folds used …

Genomics Symposium: Using Genomic Approaches To Uncover Sources Of Variation In Age At Puberty And Reproductive Longevity In Sows, Hiruni R. Wijesena, Clay A. Lents, Jean-Jack Riethoven, Melanie D. Trenhaile-Grannemann, Jennifer F. Thorson, Brittney N. Keel, Phillip S. Miller, Matt Spangler, Stephen D. Kachman, Daniel C. Ciobanu

Department of Animal Science: Faculty Publications

Genetic variants associated with traits such as age at puberty and litter size could provide insight into the underlying genetic sources of variation impacting sow reproductive longevity and productivity. Genomewide characterization and gene expression profiling were used using gilts from the University of Nebraska–Lincoln swine resource population (n = 1,644) to identify genetic variants associated with age at puberty and litter size traits. From all reproductive traits studied, the largest fraction of phenotypic variation explained by the Porcine SNP60 BeadArray was for age at puberty (27.3%). In an evaluation data set, the predictive ability of all SNP from highranked 1-Mb …

The Roles Of Age At Puberty And Energy Restriction |In Sow Reproductive Longevity: A Genomic Perspective, Hiruni R. Wijesena, Clay A. Lents, Melanie D. Trenhaile-Grannemann, Jean-Jack Riethoven, Brittney N. Keel, Jennifer F. Thorson, Phillip S. Miller, Rodger K. Johnson, Matthew L. Spangler, Stephen D. Kachman, Daniel C. Ciobanu

Department of Animal Science: Faculty Publications

Approximately 50% of sows are culled annually with more than one-third due to poor fertility. Our research demonstrated that age at puberty is an early pre-breeding indicator of reproductive longevity. Age at puberty can be measured early in life, has a moderate heritability, and is negatively correlated with lifetime number of parities. Detection of age at puberty is tedious and time consuming and is therefore not collected by the industry, which limits genetic progress. Genomic prediction is a viable approach to preselect gilts that will express puberty early and have superior reproductive longevity. The hypothesis that genetic variants explaining differences …

Economic Selection Index Development For Beefmaster Cattle Ii: General-Purpose Breeding Objective, Kathleen P. Ochsner, M. D. Macneil, Ronald M. Lewis, Matthew L. Spangler

Department of Animal Science: Faculty Publications

An economic selection index was developed for Beefmaster cattle in a general-purpose production system in which bulls are mated to a combination of heifers and mature cows, with resulting progeny retained as replacements or sold at weaning. National average prices from 2010 to 2014 were used to establish income and expenses for the system. Genetic parameters were obtained from the literature. Economic values were estimated by simulating 100,000 animals and approximating the partial derivatives of the profit function by perturbing traits 1 at a time, by 1 unit, while holding the other traits constant at their respective means. Relative economic …

Development Of An Objective Feet And Leg Conformation Evaluation Method Using Digital Imagery In Swine, J. D. Stock, J. A. Calderon Diaz, C. E. Abell, T. J. Baas, M. F. Rothschild, B. E. Mote, K. J. Stalder

Department of Animal Science: Faculty Publications

Background:The objectives of this study were to create an objective measurement method of joint angles for knee, hock, front and rear pasterns and a rear stance position in swine using digital imaging technology and to assess the repeatability of the objective measurement process. Methods and Findings: Forty-five multiparous sows (average parity 6.7 ± 2.5; parity range 5 to 14) from two commercial farms (n=21 farm 1 and n=24 farm 2) were used. Sows were moved to a pen where digital images of the profile and rear stance were captured. On average, 5.2 (± 2.6) profile and 2.6 (± 1.0) …

Effect Of Partially Replacing A Barley-Based Concentrate With Flaxseed-Based Products On The Rumen Bacterial Population Of Lactating Holstein Dairy Cows, E. Castillo-Lopez, J. Moats, N. D. Aluthge, H. A. Ramirez Ramirez, D. A. Christensen, T. Mutsvangwa, G. B. Penner, S. C. Fernando

Department of Animal Science: Faculty Publications

Aims: The effects of partial replacement of a barley-based concentrate with flaxseed-based products on the rumen bacterial population of lactating Holstein dairy cows were evaluated. Methods and Results: Treatments fed were CONT, a normal diet that included barley silage, alfalfa hay and a barley-based concentrate that contained no flaxseed or faba beans; FLAX, inclusion of a nonextruded flaxseed-based product containing 55-0% flaxseed, 37-8% field peas and 6-9% alfalfa; EXT, similar to FLAX, but the product was extruded and EXTT, similar to FLAX, but product was extruded and field peas were replaced by high-tannin faba beans. The rumen bacterial population was …

Genomic Relatedness Strengthens Genetic Connectedness Across Management Units, Haipeng Yu, Matthew L. Spangler, Ronald M. Lewis, Gota Morota

Department of Animal Science: Faculty Publications

Genetic connectedness refers to a measure of genetic relatedness across management units (e.g., herds and flocks). With the presence of high genetic connectedness in management units, best linear unbiased prediction (BLUP) is known to provide reliable comparisons between estimated genetic values. Genetic connectedness has been studied for pedigree-based BLUP; however, relatively little attention has been paid to using genomic information to measure connectedness. In this study, we assessed genomebased connectedness across management units by applying prediction error variance of difference (PEVD), coefficient of determination (CD), and prediction error correlation r to a combination of computer simulation and real data (mice …

National Beef Quality Audit-2016: Transportation, Mobility, And Harvest-Floor Assessments Of Targeted Characteristics That Affect Quality And Value Of Cattle, Carcasses, And By-Products, L.C. Eastwood, C A. Boykin, M.K. Harris, A.N. Arnold, D.S. Hale, C R. Kerth, D.B. Griffin, J.W. Savell, K.E. Belk, D.R. Woerner, J.D. Hasty, R.J. Delmore Jr., J.N. Martin, T.E. Lawrence, T.J. Mcevers, D.L. Vanoverbeke, G.G. Mafi, M.M. Pfeiffer, Ty B. Schmidt, R.J. Maddock, D.D. Johnson, C.C. Carr, J. M. Scheffler, T.D. Pringle, A.M. Stelzleni

Department of Animal Science: Faculty Publications

The National Beef Quality Audit-2016 (NBQA-2016) was conducted to assess current transportation, mobility, and quality characteristics of U.S. fed steers and heifers. Data were collected at 17 beef processing facilities between March and November 2016. About 8,000 live cattle were evaluated for transportation and mobility, and about 25,000 carcasses were evaluated on the slaughter floor. Cattle were in transit to the slaughter facility for a mean duration of 2.7 h from a mean distance of 218.5 km using trailers with dimensions ranging from 17.84 m2 to 59.09 m2. Area allotted per animal averaged 1.13 m2 and ranged from 0.85 m2 …

National Beef Quality Audit–2016: Transportation, Mobility, Live Cattle, And Carcass Assessments Of Targeted Producer-Related Characteristics That Affect Value Of Market Cows And Bulls, Their Carcasses, And Associated By-Products, M.K. Harris, L.C. Eastwood, C.A. Boykin, A.N. Arnold, K.B. Gehring, D.S. Hale, C.R. Kerth, D.B. Griffin, J.W. Savell, K.E. Belk, D.R. Woerner, J.D. Hasty, R.J. Delmore Jr., J.N. Martin, T.E. Lawrence, T.J. Mcevers, D.L. Vanoverbeke, G.G. Mafi, M.M. Pfeiffer, Ty B. Schmidt, R.J. Maddock, D.D. Johnson, C.C. Carr, J.M. Scheffler, T.D. Pringle, A.M. Stelzleni

Department of Animal Science: Faculty Publications

The National Beef Quality Audit–2016 marks the fourth iteration in a series assessing the quality of live beef and dairy cows and bulls and their carcass counterparts. The objective was to determine the incidence of producer-related defects, and report cattle and carcass traits associated with producer management. Conducted from March through December of 2016, trailers (n = 154), live animals (n = 5,470), hide-on carcasses (n = 5,278), and hide-off hot carcasses (n = 5,510) were surveyed in 18 commercial packing facilities throughout the United States. Cattle were allowed 2.3 m2 of trailer space on average during transit indicating some …

A Potential Role For Mtorc1/2 In Β2 Adrenergic Regulation Of Skeletal Muscle Glucose Oxidation In Models Of Intrauterine Growth Restriction, Robert J. Posont, Caitlin N. Cadaret, Taylor L. Barnes, Dustin T. Yates

Department of Animal Science: Faculty Publications

The epidemic of intrauterine growth restriction (IUGR) continues to be a leading cause of perinatal morbidity and mortality throughout the world. This condition has been linked to the development of metabolic health problems such as obesity, hypertension, glucose intolerance, and type 2 diabetes at all ages. Previous studies have demonstrated that IUGR fetal adaptations impair proper glucose homeostasis in part via changes in insulin responsiveness in key tissues including skeletal muscle and liver, and that these deficits persists into adulthood. Many components of insulin signaling pathways associated with glucose metabolic regulation have been evaluated in IUGR tissues for adaptive changes. …

Effect Of Harvest Method And Ammoniation On Digestibility And Intake Of Corn Residue, Ashley C. Conway, Tasha M. King, Melissa L. Jolly-Breithaupt Breithaupt, Jim C. Macdonald, Terry J. Klopfenstein, Mary E. Drewnoski

Nebraska Beef Cattle Reports

The effects of three harvest methods, both with and without ammonia treatment, on the in vivo digestibility and intake of baled corn residue were assessed in a digestion trial with lambs. Treatments included three corn residue harvest methods (conventional rake and bale, New Holland Cornrower™ with eight rows or with two rows of corn stalks chopped into the windrow containing the tailings [leaf, husk and upper stalk] from eight harvested rows) and the effects of ammoniation at 5.5% of DM compared to no ammoniation of the residue. Th e 2- Row baled residue (51.7%) had greater dry matter digestibility than …

Methods To Increase Productivity Of Spring Calving Production Systems In The Nebraska Sandhills, Devin Broadhead, L. A. Stalker, Jacki A. Musgrave Musgrave, Rick N. Funston

Nebraska Beef Cattle Reports

Feeding supplement to cattle grazing dormant winter range increased cow BW and BCS and calf performance, but not pregnancy rate. Using a CIDR to shorten the post-partum interval in a cow herd with existing acceptable reproductive performance did not improve pregnancy rate. Feeding creep feed to calves increased weaning BW but should be considered within the context of a cost/benefit analysis. Additional years of data collection may be necessary to draw definitive conclusions.

Predicting Feedlot Growth Performance Over The Feeding Period Utilizing Steer Age And Body Weight, Curtis J. Bittner, Andrea K. Watson, Jim C. Macdonald Donald, Galen E. Erickson

Nebraska Beef Cattle Reports

A pooled- analysis of UNL feedlot pens examined the effects of steer age and body weight on feedlot growth performance. For data analysis, pens were divided into 3 subclasses based on steer age (calf- fed, short yearling, or long yearling) and, grouped based upon initial body weight (500 to 1200 lb, in 100 lb increments) within each age class. As initial body weight increased, DMI (lb/d) for the whole feeding period increased quadratically in calf-fed steers and increased linearly in short and long yearlings. A quadratic increase in ADG was observed in calf- feds as initial body weight increased. No …

Acknowledgements

Nebraska Beef Cattle Reports

Appreciation is expressed to the following firms, associations, or agencies who provided grant support for research in the beef cattle program.

Agriculture and Food Research Initiative Competitive Grant/ USDA/NIFA Foundation Program: Animal Reproduction

The Beef Checkoff , Centennial, Colo

Cargill Corn Milling, Blair, Neb.

CSIRO, Commonwealth Scientific and Industrial Research Organization, Dickson, ACT, Australia

Elanco Animal Health, Indianapolis, Ind.

Huvepharma Inc. Peachtree City, GA

Dr. Kenneth and Caroline McDonald Eng Foundation San Antonio, Tex.

Lallemand Animal Nutrition. Montreal, Quebec, Canada

Merck Animal Health, Madison, NJ

National Cattlemen’s Beef Association, Centennial, Colo.

Effect Of Harvest Method On Digestibility Of Corn Residue, Tasha M. King, Melissa L. Jolly-Breithaupt, Jana L. Gramkow Gramkow, Terry J. Klopfenstein, Jim C. Macdonald

Nebraska Beef Cattle Reports

Corn residues can be an economical forage source for producers and advanced harvest methods have increased the quality of baled residue. A digestion study was conducted to evaluate the effects of harvest method of corn residues (low- stem, highstem, and conventional) on digestibility in lambs. Samples from total fecal collection were dried 1 of 3 ways to determine effects on digestibility estimates. Corn residue containing low- stem had greatest overall digestibility with high- stem residue being intermediate and conventional harvesting having the lowest digestibility. Drying method had no effect on digestibility estimates.

Comparison Of Titanium® 5 Ph- M Versus Titanium® 5 Plus Nuplura® Ph With The Presence Or Absence Of Monensin On Health And Performance Of Newly Received Feedlot Calves Fed Ramp®, Robert M. Jones, Curtis J. Bittner, F. Henry Hilscher Hilscher, Mallorie F. Wilken, Rick Stock, Galen E. Erickson

Nebraska Beef Cattle Reports

A receiving study was conducted to evaluate the effects of RAMP® with Rumensin® concentration (0 or 25.0 g/ton) given with one of two viral vaccinations (Titanium® 5 PH- M or Titanium® 5 plus NUPLURA® PH) on steer growth performance and morbidity. There were no significant vaccine by diet interactions observed. Neither vaccine treatment nor Rumensin® level affected intake, gain, or feed conversion. Vaccine type did not affect first pull (P = 0.19) or second pull morbidity rates (P = 0.52). These findings suggest that neither vaccine type nor Rumensin® concentration had any effect on steer growth performance or morbidity rate.

Evaluation Of 0 Or 300 Mg Of Optaflexx® On Growth Performance And Carcass Characteristics Of Steers Fed To Different Degrees Of Finish, Robert M. Jones, Curtis J. Bittner, F. Henry Hilscher Hilscher, Mallorie F. Wilken, Galen E. Erickson

Nebraska Beef Cattle Reports

A feedlot study evaluated the effects of ractopamine hydrochloride (Optaflexx®) dosage (0 or 300 mg/steer daily) and days on feed (118, 139, 160, 174 DOF) as a 2 × 3 + 1 factorial (steers fed 174 d were not fed Optaflexx) on performance of big yearlings. No interaction was observed between Optaflexx and days on feed. Feeding Optaflexx improved live final BW, carcass- adjusted ADG, carcass- adjusted feed conversion, and calculated yield grade. Increasing days on feed linearly increased live final BW, carcass-adjusted feed conversion, HCW, dressing percent, and marbling score but not ADG. Furthermore, a quadratic increase in LM …

Corn Residue Quality Throughout The Grazing Season, Shelby E. Gardine, Gavin L. Harsh, Robert G. Bondurant Bondurant, Jana L. Gramkow, Andrea K. Watson, Terry J. Klopfenstein

Nebraska Beef Cattle Reports

Changes in in vitro organic matter digestibility and digestible organic matter of corn residue were evaluated throughout the fall grazing and spring grazing seasons. In vitro organic matter digestibility and digestible organic matter were greatest at the beginning of fall grazing and declined over time. Slight weathering resulted in lower quality corn residue available at the beginning of spring grazing compared to the beginning of fall grazing. The in vitro organic matter digestibility of available residue declined 21% over the fall grazing season and 51% throughout the spring grazing season. As the availability of nutrients declines over time, adjustments in …

Perceptions Of Crop Consultants And Producers On Grazing Corn Residue In Nebraska, Jordan L. Cox, Kristen M. Ulmer, Manir Rakkar Rakkar, Lisa Franzen-Castle, Humberto Blanco-Canqui, Mary Drewnoski, Jim C. Macdonald, Richard J. Rasby

Nebraska Beef Cattle Reports

A survey was conducted to explore factors influencing corn residue grazing recommendations by crop consultants and producer practices in Nebraska. Approximately 80% of consultants recommended grazing corn residue, while 63% of producers allowed grazing. Of producers who did not graze, about 50% cited concerns related to soil compaction, inconvenience (lack of water, fencing, and land/equipment damage), and lack of access to livestock. Producers who allowed and consultants who recommended grazing were more likely to perceive that grazing residue increased subsequent grain yields. Most consultants (56.0%) and producers (43.8%) reported making decisions in regards to grazing based on their own observation. …

Pooled Gain Analysis Of Steers Grazing Corn Residue And Supplemented With Distillers Grains, Cody A. Welchons, Jim C. Macdonald

Nebraska Beef Cattle Reports

A pooled analysis combined data from three trials in which steer calves grazing corn residue were supplemented with distillers grains at varying amounts as a percent of BW. A regression equation was calculated in order to provide an accurate estimate of gain for calves fed distillers grains at various rates. Steers supplemented with distillers grains in a range from 0.3 to 1.1% of BW (1.5 to 6.5 lb / steer daily) had estimated gains that ranged from 1.07 to 1.94 lb / d. Th is prediction equation provides an estimate of gain for calves supplemented with distillers grains at various …

Effect Of Feeding Field Peas On Fresh Beef Quality, Hope R. Voegele, Katherine I. Domenech, Emery K. Kunze Kunze, Felipe A. Ribeiro, Karla H. Jenkins, Jim C. Macdonald, Chris R. Calkins

Nebraska Beef Cattle Reports

Th is study was conducted over two years to evaluate the use of field peas during two phases of production (grazing and finishing) on overall fresh beef quality. The backgrounding treatments included: no supplement, field peas, or dry- rolled corn and finishing treatments included the presence or absence of field peas. Loin samples (n = 232) were aged for 14 d and placed under retail display conditions for 7 d. Dietary treatments had no effect on tenderness (WBSF or SSF) or visual discoloration and minimal effects on objective color, lipid oxidation and fatty acid composition. These data indicate field peas …

Nutrient Content Of Summer-Planted Oats After Corn Harvest And Grazing Performance, Kristen M. Ulmer, Robert G. Bondurant, Jana L. Gramkow Gramkow, Mary E. Drewnoski, James C. Macdonald

Nebraska Beef Cattle Reports

Annual forages provide producers with an alternative grazing source in the fall. A cover crop grazing study was conducted following corn harvest to evaluate the steer ADG and yield of summer sown oats and turnips planted after either high moisture corn or corn silage production. Th e gain of steers grazing oats aft er silage was 1.29 lb/day, while the gain of steers grazing corn residue and oats aft er high moisture corn was 0.72 lb/day. Average oat forage production aft er silage harvest was 2857 lb/acre, while oat production following corn harvest was 523 lb/ acre. Fall forage production …

Statistics Used In The Nebraska Beef Report And Their Purpose

Nebraska Beef Cattle Reports

The purpose of beef cattle and beef product research at UNL is to provide reference information that represents the various populations (cows, calves, heifers, feeders, carcasses, retail products, etc) of beef production. Obviously, the researcher cannot apply treatments to every member of a population; therefore he/ she must sample the population. The use of statistics allows the researcher and readers of the Nebraska Beef report the opportunity to evaluate separation of random (chance) occurrences and real biological effects of a treatment. Following is a brief description of the major statistics used in the beef report. For a more detailed description …

Effect Of Heifer Development System On Reproduction And Subsequent Gain As A Pregnant Heifer, Shelby A. Springman, Hazy Rae Nielson, Tonya L. Meyer, Mike Kirby, Jim Teichert, Richard N. Funston

Nebraska Beef Cattle Reports

Weaned heifers grazed corn residue, upland range, or were fed 1 of 2 drylot diets differing in energy. Heifer development diets did not impact their resulting AI or final pregnancy rates. Cost per pregnant heifer was similar among treatments. A subset of AI- pregnant heifers was placed in a Calan Broadbent individual feeding system during late gestation. As a pregnant heifer, feed efficiency was not impacted by development system. These results indicate producers may utilize their most readily available and/or cost- effective feed resources with no detriment to pregnancy rates or feed efficiency as first- calf heifers.