About

Tara L. Felix is an Associate Professor at the Department of Animal Science at Pennsylvania State University. Her research focuses on reproductive biology, as indicated by her title and departmental affiliation. She is involved in advancing the understanding of reproductive processes in animals, contributing to the scientific knowledge in this field. Her role includes both research and teaching responsibilities, supporting the department's mission to understand animals for agriculture and companionship. Her work is integral to the department's efforts in animal reproductive health and biology, and she collaborates with other faculty members to enhance the scientific and practical understanding of animal reproduction.

Research topics

• Food science
• Animal science
• Biology
• Biomedical engineering
• Materials science
• Ecology
• Agricultural science
• Agronomy
• Chromatography
• Composite material
• Chemistry
• Economics

Selected publications

• Beef Quality Assurance (BQA) certification is associated with improved condition, mobility, carcass metrics, and economics in cull dairy cows

  JDS Communications · 2026-02-20

  articleOpen accessSenior author

  The objective of this study was to evaluate the effects of Beef Quality Assurance (BQA) certification on relevant traits of cull dairy cows. This study compared BCS, lameness scores, hot carcass weight, and carcass damage of cull dairy cows originating from BQA and non-BQA certified farm operations at the slaughter facility. A blinded observational study was completed to visually score 611 cows from 15 different dairy operations upon arrival at the holding pens of a slaughter facility. Of the 15 farms, 9 were BQA certified. Dairy cows from BQA-certified operations had improved BCS, were less lame, had greater hot carcass weight (346 vs. 283 kg), and had less carcass damage when compared with dairy cows from noncertified farms. If we assume that the difference in hot carcass weight and damage loss can be fully attributed to BQA certification, then the certification led to an additional value of US$251/cow. These findings indicate that BQA certification is associated with improved BCS, mobility, carcass outcomes, and profit potential in cull dairy cows.

  PublisherOA PDFDOI

• Effects of milk replacer composition on growth and development of beef × dairy crossbred calves

  Translational Animal Science · 2025-01-01 · 2 citations

  articleOpen access

  Abstract The production of crossbred beef × dairy (B × D) calves is increasing; however, evaluation of pre-weaning feeding strategies for B × D calves is limited. We hypothesized that both male and female B × D calves fed added fat and protein through milk replacer would have increased muscle growth, muscle fiber cross-sectional area, average daily gain, BW, and morphometric measurements. We also hypothesized that calves fed the additional fat and protein milk replacer would have upregulation of regulatory genes involved in muscle hypertrophy. SimAngus × Holstein calves (n = 42) were assigned to one of two milk replacers: 30.0% crude protein (CP), 32% crude fat (CF) milk replacer (HPHF, n = 11 males, 11 females), or 22% CP, 20% CF milk replacer (CON, n = 10 males, 10 females) from 0 to 8 wk of age. B × D calves were weighed at birth and weekly thereafter. At week 2 and 8, longissimus muscle biopsies were collected for muscle fiber cross-sectional area (CSA) or gene expression analysis. Ultrasounds were performed at 4 and 8 wk of age to quantify ribeye area (REA), and backfat and rump fat thickness. Morphometric measurements, BW, CSA, and ultrasound data were analyzed with PROC MIXED with animal as the subject and fixed effects of milk replacer, age, sex, and their interactions. Gene expression data were analyzed in R Studio. Calves that consumed the HPHF milk replacer were heavier than calves consuming the CON milk replacer (HPHF: 70.7 ± 0.39 kg; CON: 68.5 ± 0.41 kg; P < 0.01). At 8 wk of age, HPHF calves tended to have 14% larger muscle fiber CSA than CON calves (P = 0.06). No differences due to diet were observed for REA or fat thickness (P ≥ 0.38). Expression of MyoD tended to be 34% greater in CON females than HPHF females at 2 wk (P = 0.06), but at 8 wk, HPHF females tended to express 39% more MyoD than CON females (P = 0.09). Myogenin expression was 3% greater in CON calves than HPHF calves at 2 wk (P = 0.02), and CON females tended to express 52% more IGF-1 than HPHF females (P = 0.07). Feeding a milk replacer with a protein and fat content similar to beef cow milk improves B × D calf growth compared with a conventional milk replacer with less protein and fat. Improvements in early growth may improve B × D carcass quality and quantity, with the potential to increase return to the producer.

  PublisherOA PDFDOI

• The association of lung consolidation in beef × dairy cattle at weaning with feedlot growth performance, carcass characteristics, liver health, and liver microbiome diversity

  Journal of Animal Science · 2025-01-01

  articleOpen accessSenior author

  Bovine respiratory disease (BRD) is the costliest disease in the cattle industry and often compromises the immune system. The objective of this observational cohort study was to evaluate the impact of lung consolidation (LC) diagnosed at weaning (61 plus/minus 14 days of age) on feedlot growth performance, carcass characteristics, and liver health and microbiome in beef × dairy cattle. At 4 d post-weaning, LC was assessed by thoracic ultrasonography. The cattle (n = 139) either had ≥ 1 cm2 LC in at least one lung lobe and were BRD positive (35 calves; BRD) or did not (< 1 cm2) and were negative (104 calves; CONTROL). Cattle were moved to the feedlot at 353 ± 53 d of age, where individual feed intake and body weights (BW) were recorded. Cattle were sent to slaughter when they reached a target final BW (steers = 680 kg and heifers = 635 kg). Liver scores and carcass data were collected. A subset (n = 29; 18 BRD cattle vs. 11 CONTROL cattle) had healthy liver tissue analyzed to investigate the association of LC at weaning with the liver microbiome diversity at slaughter. Only cattle with edible livers and no lung lesions were included in the microbiome analysis subset. Liver tissue samples were collected at slaughter and subsequently sequenced for microbiome analysis using an Illumina platform through targeted sequencing of the V4 region of the 16S rRNA gene. Mixed linear models were used to assess the effects of LC on growth performance and carcass characteristics with calf ranch, sex, and breed as fixed effects in the model. Generalized linear mixed models were used to assess the distributions of lung scores, liver scores, and quality grade at slaughter between LC and CONTROL cattle. To assess the effect of LC at weaning on the liver microbial communities at slaughter, the beta diversity (ADONIS) test was run, and the relative abundance of taxa is presented. There were no differences between BRD and CONTROL cattle for growth performance or most carcass traits (P > 0.05). However, the marbling score was greater (P = 0.05) in carcasses from CONTROL cattle (495 ± 7.82; LSM ± SEM) when compared with carcasses from BRD cattle (462 ± 13.84). The beta diversity in the liver did not differ (P > 0.05) between BRD and CONTROL cattle. Staphylococcus was the most abundant genus among the liver samples, regardless of health status at weaning. A diagnosis of BRD by LC in beef × dairy cattle at weaning (57 ± 14 d of age) reduced marbling and impacted quality grade.

  PublisherOA PDFDOI

• PSV-1 A comparison of Dhurrin-free and conventional varieties of sorghum sudangrass baleage

  Journal of Animal Science · 2025-05-01

  articleOpen accessSenior author

  Abstract Dhurrin is a cyanogenic glycoside present in sorghum cultivars. Dhurrin is converted to prussic acid after a catalytic event, such as frost, wilting, or trampling. Prussic acid is toxic to grazing cattle, and death occurs within minutes after consumption. The objectives of this study were to compare a naturally selected, dhurrin-free (DF) sorghum sudangrass with a conventional brown midrib sorghum sudangrass (CON) to assess the nutritional composition and in-vitro ruminal disappearance. Plots were cut twice (CUT; Aug 21, 2023 and Oct 23, 2023), baled, and in-line wrapped. Bales were cored following a 28d fermentation and duplicate samples by variety (TYPE) and CUT were analyzed for dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and organic matter (OM). Sub-samples were sent for commercial analysis via near infrared spectroscopy (NIR). Samples were composited by TYPE and CUT for analysis of in-vitro ruminal disappearance. Ruminal fluid was collected and used as inoculum for incubation in an automated incubator (Daisy II, ANKOM Technology, Macedon, NY) lasting for 4, 12, 48, and 72 hours (HOUR). Samples were subsequently analyzed for DM and NDF to calculate dry matter disappearance (DMD) and neutral detergent fiber disappearance (NDFD). There was a TYPE × CUT interaction (P &amp;lt; 0.01) for DM where no differences were observed between CON and DF at 2nd cut, however, DF was 33.34% DM compared to CON which was 26.37% at 1st cut. The CP concentration was greater (P &amp;lt; 0.01) at 2nd cut, while NDF, ADF, and OM were all reduced, when compared to1st cut, regardless of TYPE. There was an impact of TYPE on ADF concentration (P &amp;lt; 0.01); where DF had 3.56% more ADF than CON, regardless of CUT. Regression models adequately related lab analysis and NIR for all variables (P &amp;lt; 0.01), validating the use of NIR to analyze dhurrin free sorghum sudangrass. There were no interactions between TYPE, CUT, and HOUR (P &amp;gt; 0.05) for DMD. However, 2nd cut had 4.86% greater (P &amp;lt; 0.01) DMD than 1st cut, regardless of variety; and, DMD increased (P &amp;lt; 0.01) over time. A TYPE x HOUR interaction (P = 0.02) occurred for NDFD at hour 48 where NDFD was 3.98% greater for CON than DF; however, NDFD was not different by variety at other time points. There was also a CUT x HOUR interaction (P = 0.03) for NDFD, where the 1st cut had a slower rate of disappearance at all time points. Final NDFD at hour 72 was 69.9% and 75.1% for the 1st and 2nd cut, respectively. Little difference existed between the nutritional composition and in-vitro ruminal disappearance of conventional and dhurrin free sorghum sudangrass when harvested at two different cuts for baleage.

  PublisherOA PDFDOI

• 297 Industry Implications of Beef x Dairy Adoption

  Journal of Animal Science · 2025-05-01

  articleOpen access1st authorCorresponding

  Abstract The practice of raising beef x dairy crossbreds, which began in 2018, is now estimated to account for 15% of the fed cattle population in the United State. Despite the rapid adoption of the breeding practices by the dairy industry, scientists have struggled to keep pace with the growth of this sector. Initially, little emphasis was placed on sire quality and the sire’s potential to influence growth performance and carcass characteristics by the dairies adopting the practice. The lack of emphasis on critical genetics for the beef sector resulted in poor acceptance of first-generation beef x dairy cattle by the packing industry. While the continuing evolution of the industry belays its resilience, challenges may be softened by the current demand for beef in the US. Care and management of beef x dairy cattle from birth is critical to the success of these cattle in the industry. At Penn State, we focus on generating data from cattle that are picked up AT BIRTH and managed throughout the entire supply chain. This is a unique approach relative to the industry at large. Opportunities exist to improve the care and management of these crossbred cattle to ensure their continued success in the market.

  PublisherOA PDFDOI

• The association of lung consolidation and respiratory pathogens identified at weaning on the growth performance of beef-on-dairy calves

  Journal of Dairy Science · 2025-01-07 · 7 citations

  articleOpen access

  This observational study evaluated the relationship between lung consolidation (LC) observed at weaning and calf ADG, and the association of pathogen shedding at weaning on ADG in beef dairy calves up to 238 d.Beef Holstein calves (n = 143) were sourced from 2 dairies.Calves were managed in 3 cohorts and fed milk replacer and calf starter before weaning.Calves were transported to another facility after weaning and raised in one group, where they were fed calf starter with oat hay and transitioned to a corn silage-based TMR diet.Calf ADG was calculated from arrival to weaning at 61 14 d (period 1), from weaning to 83 21 d (period 2), and from 83 d to 238 21 d (period 3).Thoracic ultrasonography (TUS) was performed at weaning to evaluate if a calf had LC (characterized as TUS+ if 1 cm 2 in one lobe) and to categorize the degree of LC found (none [TUS-], 1-2 cm 2 , or = 3 cm 2 ).Nasopharyngeal swabs were taken from the TUS+ calves and from pair-matched TUS-calves (n = 35 pairs) for pathogen identification by culture at a diagnostic laboratory.A mixed linear regression model assessed the association of LC with calf ADG with LC, period, period LC, and sire breed as fixed effects; arrival weight as a covariate; and calf nested within the cohort as a random effect.Another mixed linear regression model assessed the association of pathogen shedding with calf ADG from weaning to 238 d with period and sire breed as fixed effects, and pair was nested within cohort as a random effect.A logistic regression model was used to evaluate the likelihood of TUS+ calves shedding a pathogen with pair as a fixed effect.We found an LC period interaction affecting ADG over period 2 where TUS-calves had increased ADG (1.18 0.02 kg/d) compared with calves with LC = 3 cm 2 (1.03 0.04 kg/d).However, TUS-calves had similar ADG to calves with LC = 1 to 2 cm 2 in period 2. Calf ADG was not associated with LC in period 3, and calves weighed 324 37 kg (mean SD) at 238 d.In addition, 57% (20/35) of TUS+ calves and 26% (9/35) of TUS-calves shed Pasteurella multocida.We found no association of pathogen shedding with calf ADG, but TUS+ calves were more likely to shed a pathogen.These findings suggest that calves with pneumonia experienced poor growth up to 20 d postweaning, but compensatory gain occurred by 238 d.Furthermore, P. multocida was not associated with growth performance up to 238 d in beef dairy calves.

  PublisherOA PDFDOI

• 198 Forage sorghum silage as an alternative roughage source in beef cattle feedlot diets

  Journal of Animal Science · 2025-05-01

  articleOpen accessSenior author

  Abstract Forage sorghum is a summer annual crop characterized by drought tolerance, rapid growth, and adaptation to marginal soil. Corn silage is a commonly fed roughage source in feedlot diets but suffers production issues when challenged by drought and poor soil fertility. Forage sorghum can be an alternative forage source in beef cattle diets; however, its increased fiber concentration relative to corn silage may restrict growth performance. The objective of this study was to compare the effects of feeding corn silage or forage sorghum silage to cattle at equal NDF on growth performance and carcass characteristics. Crossbred beef x dairy steers (n=68, initial weight = 448 ± 4kg) and heifers (n=71, initial weight = 452 ± 3kg) were stratified by sex and sire breed and assigned to one of three treatments, based on dietary dry matter inclusion: corn silage at 20% (CORN), forage sorghum silage at 11% (SORG), or corn silage at 11% with forage sorghum silage 5.5% (BLEND). Diets included dry-rolled corn and were formulated to supply equal dietary NDF (22.4 %). Individual intakes were recorded via Growsafe Feed Intake Monitoring System (Model 400E, Vytelle, Calgary, AB, Canada). Steers and heifers were fed to a target final body weight (BW) of 680kg and 635kg, respectively, and were slaughtered in 5 groups. Dry matter intake (DMI) was 8% and 6% greater (P &amp;lt; 0.01) when cattle fed SORG and BLEND, respectively, were compared to cattle fed CORN. Average daily gain (ADG) was 5% and 4% greater (P = 0.02) for cattle consuming SORG and BLEND, respectively, when compared to cattle consuming CORN. The increase in both ADG and DMI resulted in similar (P = 0.20) gain to feed ratios regardless of treatment. Cattle fed SORG tended (P = 0.07) to have 12kg and 3kg heavier shrunk final BW than cattle consuming CORN and BLEND, respectively. Although shrunk final BW tended to be different, hot carcass weight (HCW) and dressing percent (DP) did not differ (P &amp;gt; 0.05) by treatment. No differences (P &amp;gt; 0.05) were detected for any other carcass characteristics. Cattle fed CORN had a greater (P = 0.02) back calculated NEm and NEg than cattle fed SORG, while cattle consuming BLEND were intermediate. These data suggest that forage sorghum silage can replace some or all of the corn silage in feedlot cattle diets without negatively impacting growth or carcass performance when balanced to equal dietary NDF.

  PublisherOA PDFDOI

• Predictive ability of a commercial mixed-breed genomic test for feedlot performance and carcass traits of beef × Holstein steers

  Journal of Animal Science · 2025-01-01

  articleOpen access

  Genomic tests are marketed as a method to appraise cattle value prior to feedlot entry. We aimed to evaluate the use of a commercial, multi-breed genomic test to predict terminal production characteristics of beef × Holstein steers. Phenotypes of feedlot performance and carcass characteristics were evaluated in beef × Holstein steers (n = 259) sired by 8 beef breeds. Steers were genotyped with Igenity Beef (Neogen Corporation, Lansing, MI), which ranks cattle for individual traits and by selection indexes on a scale of 1 to 10. Trait rankings were converted to molecular breeding values (MBV) derived from genotype. Expected progeny differences (EPD) of each steer's sire were accessed from their respective breed associations. U.S. Meat Animal Research Center across-breed adjustments for beef cattle were applied to growth and carcass sire EPD for all cattle except for the 11 Wagyu-sired steers (n = 248 steers with sire EPD). Breed-adjusted sire EPD and MBV of traits were correlated with associated phenotypes of beef × Holstein steers and phenotypes were regressed on sire EPD and MBV. Sire EPD and MBV of yearling weight (YW) and hot carcass weight (HCW) were positively associated with initial and final feedlot body weight, respectively. The MBV of average daily gain (ADG) was not associated with phenotypic ADG, though greater derived sire EPD of ADG was associated with greater ADG and dry matter intake (DMI). The MBV of residual feed intake (RFI) was associated with DMI (P = 0.02) but not RFI or gain-to-feed ratio. Each kg of RFI predicted by MBV resulted in 0.31 kg greater ADG (P < 0.01), suggesting that MBV of RFI in beef × Holstein steers are not independent of the rate of gain. For each kg of HCW predicted by MBV and sire EPD carcasses were 0.52 and 0.80 kg heavier (P < 0.01). Neither sire EPD nor MBV of ribeye area and backfat thickness were related to the corresponding phenotypes of beef × Holstein carcasses (P > 0.05). Both MBV and sire EPD of marbling score were strong predictors of marbling score and intramuscular fat content (P < 0.05). Tenderness MBV accurately predicted tenderness of the longissimus muscle of beef × Holstein progeny (P < 0.01). Igenity Beef Terminal Index ranking was associated with greater feedlot profitability (P = 0.03), but marbling MBV and sire EPD were more strongly associated with feedlot net profit (P < 0.01). Breed-adjusted sire EPD performed similarly to Igenity Beef MBV in predicting growth performance, carcass characteristics, and net profit of beef × Holstein steers.

  PublisherOA PDFDOI

• 46 Impacts of lung consolidation at weaning on feedlot growth performance and carcass characteristics in beef × dairy calves

  Journal of Animal Science · 2025-05-01

  articleOpen accessSenior author

  Abstract Bovine respiratory disease (BRD) is the leading cause of death in calves and can affect cattle at different ages. Dairy calves with BRD at weaning had decreased average daily gain (ADG) and decreased future milk production. However, the impacts of BRD on the lifetime growth performance of beef x dairy cattle, reared in similar systems, is unknown. The objective was to evaluate the impact of lung consolidation in calves (n=139 beef × Holstein) at weaning on feedlot growth performance and carcass characteristics. Calves were sourced from two dairies and raised in three cohorts. Calves with ≥ 1 cm2 in at least one lobe at 4 d post-weaning via thoracic ultrasonography (TUS) were deemed to have lung consolidation (TUS+). Calves were fed milk replacer (0.84 kg/d) with ad-lib access to calf starter and water until weaned, 57 ± 14 d. At 4 ± 2 d post-weaning, calves moved to a growing farm. At 329 d of age, cattle were moved to the feedlot (60 km) where they were fed a total mixed ration ad libitum. Calf ADG was calculated by periods: pre-weaning ((1 to 4 d of age – weaning wt)/d), post-weaning ((weaning wt – 329 d wt)/d), and feedlot ((329 d wt - final wt)/d). The targeted final weight for steers and heifers was 680 kg and 635 kg, respectively. Cattle were sent to slaughter in 5 loads. Mixed linear models assessed associations of TUS+ status with ADG (pre-weaning, post-weaning, and feedlot), dry matter intake (DMI), feedlot arrival body weight (ABW), final body weight (FBW), feed efficiency (GF), hot carcass weight (HCW), dressing percentage, ribeye area (REA), marbling score, 12th rib fat thickness (BF), and calculated yield grade. Models included source dairy, calf ranch, and gender as fixed effects and breed as a random effect. At weaning, 35 calves were diagnosed with BRD by TUS+. There were no differences (P&amp;gt;0.05) between calves diagnosed with BRD and calves defined as healthy calves for ADG, DMI, ABW, FBW, or feed efficiency. Similarly, there were no differences (P&amp;gt;0.05) in HCW, dressing percentage, REA, BF, and calculated yield among calves diagnosed with BRD at weaning and healthy calves. However, the marbling score was greater (P=0.02) in carcasses from healthy calves (492 ± 12) compared to carcasses from calves with BRD (448 ± 18). These data suggest lung consolidation at weaning in beef x dairy cattle did not have long-term effects on growth performance but compromised marbling.

  PublisherOA PDFDOI

• Effects of forage sorghum silage as an alternative roughage source in feedlot cattle diets

  Applied Animal Science · 2025-11-22

  articleOpen accessSenior author
  PublisherDOI

Frequent coauthors

• S. C. Loerch

  College of Wooster

  37 shared

• Daniel W Shike

  University of Illinois Urbana-Champaign

  23 shared

• Pedro H V Carvalho

  Colorado State University

  19 shared

• F. L. Fluharty

  University of Georgia

  17 shared

• Adam Schroeder

  University of Illinois Urbana-Champaign

  9 shared

• A. C. Dilger

  University of Illinois Urbana-Champaign

  9 shared

• Joshua C McCann

  University of Illinois Urbana-Champaign

  8 shared

• F.A.S. Silva

  Universidade Federal de Viçosa

  8 shared

Labs

• Felix LabPI

Education

• B.S., Animal Bioscience

  Penn State University

• M.S., Ruminant Nutrition

  University of Florida

• Ph.D., Ruminant Nutrition

  The Ohio State University