About

Dr. Carrie Pickworth is an Associate Professor in the Department of Animal Science at North Carolina State University. Her academic focus includes Ruminant Management and Nutrition, with teaching responsibilities spanning from pre-college Livestock Science Camp to associate-level Animal Feeds and Nutrition, baccalaureate Beef Cattle Management, and graduate-level Applied Ruminant Nutrition. Her research program is diverse, supporting projects related to beef cattle and sheep nutrition and management, including topics such as weaning stress, fescue toxicosis, and stocker cattle grazing cover crops.

Research topics

• Biology
• Animal science
• Genetics
• Medicine
• Botany
• Agronomy
• Endocrinology
• Veterinary medicine

Selected publications

• 136. Evaluation of Performance and Nutritional Intake in Angus Cow-Calf Pairs During Pregnancy and Lactation

  Journal of Animal Science · 2026-04-01

  articleOpen access

  Abstract The nutritional demands of beef cows fluctuate across physiological and production stages, yet changes in efficiency as females transition from pregnancy to lactation and the effects of consuming endophyte-infected (EI) rations on metrics like residual feed intake (RFI) remain unclear. Therefore, this two-year study evaluated feed intake (FI) and physiological parameters of cow-calf pairs across pregnancy and lactation. In year 1, purebred Angus pregnant heifers (452.6±10.2 kg; 17-19 mo of age; n = 16) were fed an endophyte-free (EF) ration for 56 days. Individual FI was recorded using the Vytelle® Sense system, and weekly measurements were collected to monitor growth and physiological changes. In year 2, the same females (444.4±12.5 kg; 29-31 mo of age; n = 16) were reintroduced to the Vytelle® Sense system with their calves (166.4±8.5 kg; 5-7 mo of age; n = 16) during late lactation and were fed an EI ration. The same physiological measurements as in year 1 were recorded biweekly. Additionally, the Weigh-Suckle-Weigh (WSW) method was used to estimate individual energy-corrected milk production in cows. In both years, biweekly ration samples were collected to assess nutritional content and ergot alkaloid concentrations in the EI ration. A post hoc analysis of FI data estimated RFI for each year and assessed RFI category repeatability across years. Physiological data from cows and calves were analyzed using the MIXED procedure with repeated measures in SAS®. Effects of RFI category, time, and their interactions were evaluated for weight (BW), ADG, Body Condition Score (BCS), Hair Shedding Score (HSS), and FI. In year 2, these effects were also evaluated for milk (MILK) production in cows. For calves, effects of sex, dam RFI, time, and their interactions were analyzed for BW, ADG, BCS, HSS, and FI. In year 1, no differences were observed in BW, ADG, and BCS, while low-RFI (LRFI) heifers had lower HSS (2.3±0.2 vs 3.1±0.2; P = 0.0204) and tended to have lower FI (74.1±2.7 vs 80.9±2.4 kg DM; P = 0.0671) than high-RFI (HRFI) heifers. In year 2, 57% of dams retained the LRFI category and 78% retained HRFI. Based on this classification, no differences were observed in BW, ADG, BCS, and MILK, whereas LRFI cows had lower FI (73.6±3.4 vs 83.8±2.5 kg DM; P = 0.0159) and tended to have lower HSS (2.6±0.5 vs 3.7±0.4; P = 0.0987) than HRFI cows. For the calves, no differences were observed in BW, ADG, BCS, HSS, and FI. These findings indicate that the RFI category remains moderately consistent across pregnancy and lactation, and that a greater hair shedding ability may support feed efficiency in beef cattle.

  PublisherOA PDFDOI

• 83. Deworming Strategies for Parasite Control in Weaning Beef Cattle

  Journal of Animal Science · 2026-04-01

  articleOpen accessSenior author

  Abstract Gastrointestinal nematode (GIN) parasites pose a significant health concern for beef cattle producers in North Carolina, where the warm, humid climate supports year-round parasite survival and transmission. Calves are particularly vulnerable at weaning, a period of high stress when fecal egg counts (FEC) often peak due to immature immunity and increased physiological demands. The objective of this study was to evaluate the effects of deworming timing before or at weaning on calf health and performance. A total of 90 Angus-based calves (steers: n = 52, and heifers: n = 38; average 7 mo) were randomly assigned to two treatment groups: (1) administration of Dectomax® according to label directions at pre-weaning vaccination (∼4 weeks before weaning, d14) or (2) administration at weaning (d42). Body weight (BW), body condition score (BCS), FEC, and average daily gain (ADG) were collected every 14d from d42 pre-weaning (d0) through d28 post-weaning (d70). The FEC was determined using a Modified McMaster’s procedure with a triple-chamber slide and reported as eggs per gram (EPG). Data were analyzed in SAS (PROC MIXED), with significance defined as P ≤ 0.05 and trends at 0.05< P < 0.10. The BW increased across the study period for all calves (P < 0.001), with steers consistently weighing more than heifers (158 vs. 144 kg, respectively). Steers also maintained higher BCS than heifers (4.4 vs. 4.2, respectively, P < 0.01). Treatment timing had no effect on BW (P > 0.10) or BCS (P > 0.10). The FEC tended to decrease after deworming in both groups (100 vs 150 EPG decrease for pre-wean and at wean deworming in 14d post-deworming), but no treatment effect was detected (P > 0.10). Unexpectedly, only 25% of calves achieved ≥90% fecal egg count reduction (FECRT) within 14d post-treatment, below the industry benchmark. Further investigation is needed to determine if there is reduced efficacy of Dectomax® in this herd. The ADG followed standard growth trends but was not different (P > 0.10) between treatment groups. Deworming at pre-weaning vaccination may provide slight advantages by reducing parasite exposure during a lower-stress period, but overall timing of Dectomax® administration did not alter performance outcomes in this study. Evidence of suboptimal FEC reduction highlights the need for FECRT, exploration of alternative anthelmintic protocols, and integrated parasite management approaches.

  PublisherOA PDFDOI

• 281 Career Crossroads: Evaluating changes in Animal Science career plans after a food animal research experience

  Journal of Animal Science · 2025-05-01

  articleOpen accessSenior author

  Abstract One of the greatest challenges in food animal production is a need to meet the dietary demand of an ever-growing population. According to a study conducted by Purdue University in 2015 (https://www.purdue.edu/usda/employment), US college graduates have good job opportunities if they first gain experience in food and agriculture through high impact experiences like internships and research. At NC State University, we have approximately 850 students pursuing a bachelor’s degree in Animal Science. Approximately 20% of our students come from under-represented groups, ~21% come from the most economically distressed North Carolina counties, with ~22% being Pell grant recipients. Upon entering the university, 96% of these students report career aspirations of veterinary medicine, but only about 10% pursue a doctorate in veterinary medicine, thus leaving a large number of these graduates to pursue alternative careers. This pool of undergraduates represents an enormous, untapped resource able to contribute to the betterment of US animal production. Our ASSURE (Animal Science Summer Undergraduate Research Experience) program targets sophomore and junior students that are under-resourced (i.e., underrepresented, disabled, economically disadvantaged, rural and first generation students), and aims to (1) to create an intensive 12-week hands-on experience in fundamental and applied research, (2) to develop and refine their essential workforce skills and enhance future employment, and (3) to strengthen and advance their understanding of the opportunities available in food animal-related careers and graduate programs. To date we have completed 3 cohorts of Scholars with two additional cohorts to be selected for 2025 and 2026. Since its inception, 28 ASSURE Scholars have completed the program. In this talk, we will discuss the various aspects of the ASSURE program and the impact the program has had on the career plans of these Scholars.

  PublisherOA PDFDOI

• 192 Awardee Talk: Assessing performance metrics and nutritional intake to determine efficiency in Angus heifers at different production stages

  Journal of Animal Science · 2025-06-01

  articleOpen access

  Abstract Nutritional requirements and intake of beef cows vary across different growth and production stages, and the selection of replacement females with increased nutritional efficiency may improve the cow herd productivity. However, it remains unclear if animals exposed to ergot alkaloids maintain their nutritional efficiency metrics, such as residual feed intake (RFI) and weight gain (RADG), across different production stages. This two-year study aimed to evaluate changes in nutritional intake, and in various physiological and performance parameters of heifers across different production stages. In year 1, purebred Angus heifers (216.3±6.1 kg; 911 mo of age; n=36) were randomly separated and fed either an endophyte-infected (EI) or endophyte-free (EF) ration for 49 days. On day 1, temperature data loggers were inserted intravaginally to record vaginal temperature (VT) on a 20-minute-frequency throughout the entire study. Weekly measurements were collected to monitor growth and physiological responses of both treatment groups. Individual feed and water intakes were measured utilizing the Vytelle® Sense system. In year 2, all heifers were exposed to an ultrasonography assessment for pregnancy detection, and those confirmed as pregnant (431.47±9.1 kg; 17-19 mo of age; n=27) were sorted back into year 1 groups, reintroduced to the Vytelle® Sense system, and were all fed an EF ration for 56 days. The same physiological and performance measurements were collected on the same frequencies as on year 1. A post hoc analysis using the individual feed (FI) and water intake (WI) data evaluated RFI, RADG, total WI and WI per body weight (WI/BW). All physiological and performance data were analyzed using a MIXED procedure with repeated measures and a CORR procedure to estimate Pearson correlations for RFI and RADG in SAS. The effects of treatment, time, and its interactions were evaluated for BW, ADG, Body Condition Score (BCS), Hair Shedding Score (HSS), VT, FI and WI. In year 1, EF heifers had greater BW, ADG, and BCS, and lower VT and HSS over time (P <0.0001) than the EI heifers. The EF heifers also reported greater FI (P <0.0001) but lower WI (P=0.0144) and WI/BW (P=0.0132) than EI heifers over time. In year 2, no differences were observed in BW, ADG, BCS, HSS, and VT between groups. The EF heifers had a greater FI (P=0.0458) and tended to have a greater WI (P=0.0616) than EI heifers over time, but no differences were observed in WI/BW. In a longitudinal comparison, both groups had greater BW, ADG, and FI (P <0.0001) in year 2 than in year 1, while the WI/BW of both groups was greater (P <0.0001) in year 1 than in year 2. Additionally, no differences were observed in BCS, VT, and WI of both groups between years. A strong correlation was observed between years in the RFI of EI heifers (r=0.622), but a very weak correlation was found in their EF pairs (r=-0.150). Additionally, moderate correlations were observed during the same period in the RADG of the EI (r=0.439) and EF (r=0.374) groups. Moreover, 80% of the EI heifers that had a negative RFI after year 1 maintained a negative score after year 2, whereas 75% of the EI heifers with a positive RFI after year 1 retained a positive score after year 2. In contrast, no differences were observed for the RFI of EF heifers, as 50% of both the positive and negative scores in year 1 did not maintain their score after year 2. For the RADG, 60% of the EI heifers that had a positive score in year 1 maintained a positive score after year 2, whereas 63% of the EI heifers that had a negative score in year 1 retained a negative score after year 2. Similarly, 75% of the EF heifers that had a positive RADG after year 1 retained a positive score after year 2, whereas 67% of the EF heifers that had a negative RADG after year 1 maintained a negative score after year 2. Based on these data, exposure to an EI ration negatively impacts nutritional intake, which consequently decreases animal physiological and performance parameters. However, the EI heifers had a greater retention percentage of RFI scores than their EF pairs while maintaining similar retention rates of the RADG scores, suggesting that these efficiency metrics may not be severely impacted by ergot alkaloid exposure or pregnancy status. Future research focusing on long-term evaluations of the retention of nutritional efficiency parameters and their relationship with physiological stressors will improve the productivity of the beef cattle industry.

  PublisherOA PDFDOI

• Influence of heat stress and fescue toxicosis on the pulmonary arterial pressure of beef heifers

  Journal of Animal Science · 2025-01-01 · 1 citations

  articleOpen access

  Peripheral vasoconstriction is a major consequence of fescue toxicosis (FT). However, it remains unclear if major blood vessels, such as the pulmonary artery, are impacted by this disease. This study aimed to evaluate changes in pulmonary arterial pressure (PAP) and different physiological parameters in replacement beef heifers consuming an endophyte-infected (EI) ration. Purebred Angus heifers (216.3 ± 6.1 kg; 9 to 11 mo of age; n = 36) were randomly separated and fed either an EI or endophyte-free (EF) total mixed ration for 49 d. On day 1, iButton temperature data loggers were inserted intravaginally to record temperature every 20 min throughout the entire study. The cattle comfort index (CCI) was used to assess comfort and define exposure to heat stress as thermoneutral, mild heat stress (MILD-HS), or moderate heat stress (MOD-HS). PAP was measured every 20 d to assess its response to ergot alkaloid and heat stress exposure. Weekly measurements were recorded to monitor growth and physiological responses of both treatment groups. Data were analyzed using the MIXED procedure of SAS with repeated measures. Both groups were exposed to MILD- and MOD-HS on several occasions. An interaction between PAP results and heat stress exposure was identified, as both groups reported increased PAP values as CCI values decreased. The EF heifers ended the study with greater body weight (P < 0.05), average daily weight gain (P < 0.01), body condition score (P < 0.01), and lower hair shedding score (P < 0.01) than EI heifers. In contrast, EI heifers maintained greater vaginal temperatures throughout the study (P < 0.01). Additionally, EI heifers reported lower caudal artery diameters (P < 0.01) than the EF heifers, but no differences were observed in caudal vein diameters (P > 0.05). Lastly, no differences were observed in the packed cell volume and prolactin concentrations (P > 0.05). While the EI group displayed classical symptoms of FT, including caudal artery vasoconstriction, the PAP results indicate that ergot alkaloid consumption does not induce vasoconstriction on the pulmonary artery, but rather reflect that PAP may be altered by the exposure to heat stress. Additional research should be conducted in regions where changes in PAP are of interest to fully understand the effects of heat stress exposure on the cardiopulmonary system of cattle. Moreover, future investigations in EI fescue-dominant environments should focus on developing strategies to mitigate the negative consequences of FT and heat stress, in order to enhance animal welfare, productivity, and profitability in the beef industry.

  PublisherOA PDFDOI

• 99 Interaction between feed efficiency and infrared thermography in beef heifers exposed to ergot alkaloids

  Journal of Animal Science · 2025-06-01

  articleOpen access

  Abstract The integration of precision livestock technologies facilitates identification of animals with superior productivity and efficiency traits despite exposure to environmental stressors. The objective of this study was to evaluate changes in nutritional intake and thermoregulatory response in heifers consuming an endophyte-infected (EI) ration. Angus heifers (216.3 ± 6.1 kg; 9-11 mo of age; n = 36) were randomly separated and fed either an EI or endophyte-free (EF) ration for 49 days. On day 1, temperature data loggers were inserted intravaginally to record vaginal temperature (VT) on a 20-minute-frequency throughout the entire study. Weekly measurements were collected to monitor growth and physiological responses of both treatment groups. Infrared thermography (IRT) of the ocular globe (OGT) and rib skin area (RIBT) posterior to the left scapula were recorded weekly. The comprehensive climate index (CCI) was used to assess exposure to environmental stress and determine its impact on physiological measurements. Individual feed and water intake was measured utilizing the Vytelle® Sense system, and the final residual feed intake (RFI) rankings were used for a post hoc analysis to identify cattle as either feed efficient (LRFI; n = 6) or inefficient (HRFI; n = 6) in both groups and determine its correlation to the VT and thermography results. Data were analyzed using a MIXED procedure of SAS with repeated measures. The effects of treatment and time were evaluated for Body Weight (BW), ADG, Body Condition Score (BCS), Hair Shedding Score (HSS), VT, OGT, RIBT, Feed Intake (FI), and Water Intake (WI). The EI heifers had lower BW, ADG, and BCS, and greater HSS over time (P&amp;lt; 0.0001), and also had greater VT (40.1 ± 0.1 vs 39.5 ± 0.1 ̊ C; P&amp;lt; 0.0001), RIBT (36.6 ± 0.1 vs 35.5 ± 0.1 ̊ C; P&amp;lt; 0.0001), and OGT (34.9 ± 0.1 vs 34.5 ± 0.1 ̊ C; P&amp;lt; 0.0001) than EF heifers. Moreover, an interaction between treatment and efficiency was observed where EI-LRFI and EI-HRFI had greater VT (P&amp;lt; 0.0001) and RIBT (P&amp;lt; 0.0001), and tended to have greater OGT (P=0.0671) than their EF pairs. However, no differences were observed within treatments between LRFI and HRFI heifers. In terms of nutritional intake, EF heifers had greater FI (P&amp;lt; 0.0001) but lower WI (P=0.0144) than EI heifers over time, and differences (P&amp;lt; 0.0001) were also observed in the duration and frequency of visits to the feed bunks and water troughs of both groups that were correlated to increased CCI values. Exposure to ergot alkaloids negatively impacts the physiological status and production efficiency of growing heifers by altering the animal’s thermoregulatory ability. Developing a better understanding of the mechanisms controlling these symptoms will improve beef cattle production and provide potential therapeutic interventions for disease treatment.

  PublisherOA PDFDOI

• 136 Evaluation of internal parasite burden in grazing beef cattle in North Carolina over a production lifecycle

  Journal of Animal Science · 2024-03-01

  articleOpen access

  Abstract Gastrointestinal nematode (GIN) parasite infections can be detrimental to not only cattle health and immunity, but also result in economic loss and poor performance. Cattle grazing in the southeast are challenged even further by the favorable environmental conditions for parasite development, especially those animals who have yet to develop an immunity to combat parasitism. To diminish potential economic and performance-based losses, many beef producers treat animals for GIN parasites with anthelmintics on a regular basis without proper diagnosis. Anthelmintic resistance(AR) develops when deworming products are overused and misused. To minimize the development of AR, selective deworming and sustainable management practices should be implemented. However, the severity of parasite burden over the production cycle needs to be better understood in beef cattle herds before recommendations can be made. Thus, the objective was to investigate the rates of GIN parasite infections through fecal egg counts (FEC) and the impact on body weight (BW) and body condition score (BCS). Angus-based cattle (6 mo-13 yr, n = 1,154) on a were utilized from five different research and educational herds across North Carolina. Cattle were categorized based on their age at the start of the project as either calves (n = 446), yearling heifers (n = 205), 2 year old (n = 260), 3-5 year old (n = 501), or 6+ year old (n = 206). Starting in September, FEC, BW, and BCS were collected and analyzed every 90 d at critical production timepoints (calving, breeding, weaning, and 90d post-weaning) to monitor the severity of GIN parasite challenge. Cattle on study were not treated with anthelmintics regardless of parasite load, with the exception of calves at four of the locations at the time of weaning. All data were analyzed using Proc MIXED in SAS with repeated measures. Statistical significance was declared at P ≤ 0.05 and a trend at 0.10 &amp;gt; P &amp;gt; 0.05. Age of cattle had an impact on FEC overall (P &amp;lt; 0.05), however, there was no difference between FEC of mature cattle over 3 yr (4.29 ± 4.9 eggs/gm). Calves had the greatest FEC (120.59 ± 4.2 eggs/gm) while cattle 6+ yr had the least (3.68 ± 4.5 eggs/gm). Cattle age at each location affected BCS and BW (P &amp;lt; 0.05). Between age groups across locations, time had an impact on FEC, BW, and BCS (P &amp;lt; 0.05). There was also a tendency (P = 0.6) for location to impact FEC. Calf sex did not affect (P &amp;gt; 0.05) FEC. Further FEC analysis of cattle under 2 yrof age is required to better understand when a natural immune response to GIN parasite infections develops.

  PublisherOA PDFDOI

• Exploring the impacts of fescue toxicosis on the pulmonary arterial pressure of angus cows

  Journal of Animal Science · 2024-01-01 · 1 citations

  articleOpen access

  Vasoconstriction of peripheral blood vessels is one of the hallmark symptoms of fescue toxicosis in cattle. Thus, it was hypothesized that exposure to ergot alkaloids would increase the pulmonary arterial pressure (PAP). The objectives of this study were to examine the relationship between PAP and different physiological parameters of cows grazing either endophyte-infected (EI) or novel-endophyte (EN) fescue, then evaluate changes in PAP and other physiological measurements in cows exposed to EI pastures and deemed as susceptible or tolerant based on animal performance. Pregnant Angus cows at 2 different locations grazed either EI or EN fescue pastures for 14 consecutive weeks starting in early April of 2022. Forage measurements were collected to assess ergot alkaloid exposure throughout the study. In addition to measuring PAP, weekly measurements and blood samples were collected to evaluate physiological responses to ergot alkaloid consumption. The Fescue Toxicosis Selection Method (FTSM) was used for a post hoc analysis to identify cattle as either tolerant (EI-TOL) or susceptible (EI-SUS) when challenged with ergot alkaloid exposure. Data were analyzed using a MIXED procedure of SAS with repeated measures. Cows grazing on EN pastures had greater mean PAP values than EI cows, (P < 0.01), whereas a location effect was identified when comparing both EI-TOL and EI-SUS groups (P < 0.01). Cows exposed to EN pastures had greater average daily gain (ADG) (P = 0.04) and progesterone (P4) concentrations (P < 0.01), and lower hair shedding scores (HSS; P < 0.01) than EI cows. The EI-TOL cows tended to have greater final body weight, ADG and had lower HSS (P < 0.01) than EI-SUS cows. While cattle consuming EI tall fescue exhibited classical physiological changes, the decrease in PAP of cattle consuming EI fescue was unexpected and contradicted the initial hypothesis. Furthermore, the FTSM provides a means to identify animals with superior performance in spite of the chronic exposure to ergot alkaloids. Continued investigations examining the interaction between ergot alkaloid exposure and cardiovascular parameters will lead to a fuller understanding of the disease and are pivotal for developing innovative strategies that enhance best management practices to help guarantee the sustainability of the U.S. beef industry.

  PublisherOA PDFDOI

• 106 Exposure to ergot alkaloids and heat stress alter pulmonary arterial pressure and nutritional intake in beef heifers

  Journal of Animal Science · 2024-09-01 · 1 citations

  articleOpen access

  Abstract Ergot alkaloid consumption is detrimental to cattle as it negatively impacts several physiological and performance parameters. The objective of this study was to evaluate changes in nutritional intake and different physiological and performance parameters of heifers consuming an ergot alkaloid-infected ration. Purebred Angus heifers (216.3 ± 6.1 kg; 9 to 11 mo of age; n = 36) were randomly separated and fed either an endophyte-infected (EI) or endophyte-free (EF) total mixed ration (TMR) for 49 d. On d 1, iButton temperature data loggers were inserted intravaginally to record temperature on a 20-min frequency throughout the entire study. Individual feed and water intake was measured utilizing the Vytelle Sense system. Hourly environmental temperature and relative humidity measurements were utilized to calculate the temperature-humidity index (THI) and define exposure to heat stress as Thermoneutral (NO-HS), Mild (MILD-HS) and Moderate (MOD-HS). Pulmonary arterial pressure (PAP) was measured every 20 d to assess its response to ergot alkaloid and heat stress exposure. Additionally, weekly measurements were collected to monitor growth and physiological responses to EI-TMR intake. Data were analyzed using a MIXED procedure of SAS with repeated measures. The effects of treatment, day, THI and its interactions were evaluated for body weight (BW), average daily gain (ADG), body condition score (BCS), hair shedding score (HSS), vaginal temperature (VT), feed intake (FI), water intake (WI) and PAP. EF heifers had significantly less HSS and greater BW, ADG, and BCS than EI heifers over time (P &amp;lt; 0.0001). EF heifers also had lower VT than EI heifers (39.5 ± 0.1 vs 40.1 ± 0.1° C; P &amp;lt; 0.0001) and had reduced daily WI (8.3 ± 0.4 vs 9.4 ± 0.4 L; P &amp;lt; 0.0001). Moreover, WI was also found to be positively correlated to THI, as both EF and EI groups significantly increased (P &amp;lt; 0.0001) their WI as THI increased from NO-HS (5.9 ± 0.6 vs 7.4 ± 0.6 L) to MILD-HS (9.4 ± 0.6 vs 10.8 ± 0.6 L) and MOD-HS (12.8 ± 0.6 vs 13.4 ± 0.6 L). EF heifers also had greater daily FI than EI heifers (18.8 ± 0.6 vs 12.9 ± 0.6 kg; P &amp;lt; 0.0001), and FI was also affected by THI as intake in both EF and EI groups decreased when transitioning from NO-HS (21.3 ± 0.6 vs 14.6 ± 0.6 kg) to MILD-HS (16.4 ± 0.6 vs 11.1 ± 0.6 kg; P &amp;lt; 0.0001). PAP results tended to differ between groups (29.6 ± 0.6 vs 31.1 ± 0.6 mm Hg; P = 0.0954) and increased in both EF and EI groups when transitioning from MILD-HS (27.2 ± 0.9 vs 26.2 ± 0.9 mm Hg) to NO-HS (34.8 ± 0.9 vs 36.4 ± 0.9 mm Hg; P = 0.0147). Based on these data, exposure to ergot alkaloids negatively affects animal performance as it decreases ADG, BCS and increases HSS and VT, and it also increases daily WI and reduces daily FI. Furthermore, PAP, WI and FI were also negatively impacted by changes in THI and exposure to heat stress. Additional research is necessary to understand the interactions between these variables to identify efficiency parameters.

  PublisherOA PDFDOI

• 103 Impact of Fescue Variety on Fecal Egg Counts in Mature Beef Cattle

  Journal of Animal Science · 2023-05-01

  articleOpen accessSenior author

  Abstract Fescue toxicosis decreases beef cattle performance in a multitude of ways, including decreased health and immunity. Cattle challenged by fescue toxicosis are often grazing in an environment favorable for development of gastrointestinal nematodes (GIN). Interactions of fescue toxicosis and parasite challenge may result in further performance and economic losses. Many beef producers treat animals regularly for GIN parasites with little insight on necessity or effectiveness of anthelmintic products. Overuse of anthelmintics can result in development of anthelmintic resistance in GIN populations. To minimize the development of anthelmintic resistance, implementation of selective deworming practices should be considered. However, level of parasite burden and effects of fescue toxicosis on parasite burden need to be better understood in beef cattle herds before recommendations can be offered. Therefore, the objective was to investigate the impact of fescue toxicosis on GIN parasite infection rates through fecal egg counts (FEC), body weight (BW), hematocrit (HCT), and body condition score (BCS). Starting in April, for 14 consecutive weeks post-weaning, pregnant Angus-based cows (2 to 4 years old, n = 65) were rotationally grazed on either novel endophyte (EN) fescue or endophyte-infected (EI) fescue pastures. Hematocrit, BCS, and BW were assessed weekly, while FEC were measured bi-weekly to monitor the physiological changes as a result of consuming endophyte-infected tall fescue. All data were analyzed using Proc MIXED in SAS with repeated measures. Statistical significance was declared at P ≤ 0.05 and a trend at 0.10 &amp;gt; P &amp;gt; 0.05. Overall, FEC were low (4.2 ± 0.9 eggs/gm) in these mature cattle and grazing EI or EN fescue did not have any overall effect (P &amp;gt; 0.05) on the FEC. However, FEC decreased (P &amp;lt; 0.05) over the course of the study from week 1 to week 13. Body weight, HCT, and BCS were not affected (P &amp;gt; 0.05) by the type of fescue grazed. There was a tendency (P &amp;lt; 0.10) for 2-3 and 4-6 year old cattle to have lower BW when grazing EI compared with EN fescue while cattle &amp;gt;7 were not affected. Cattle gained BW (P &amp;lt; 0.05) over the 14-week study (471.4 and 527.7 ± 0.6 kg, 0 and4 week respectively). For cattle grazing EI fescue, HCT linearly decreased (P &amp;lt; 0.05) from week 1 to week 14 whereas cattle grazing EN fescue had a linear increase (P &amp;lt; 0.05) in HCT from week 1 to week 14. More research is warranted to investigate beef cattle FEC and the potential impact of fescue type on FEC in younger beef cattle.

  PublisherOA PDFDOI

Frequent coauthors

• Daniel Poole

  Louisiana State University

  20 shared

• Mikayla F Moore

  Oklahoma State University Oklahoma City

  16 shared

• Matt H Poore

  North Carolina State University

  14 shared

• M. H. Poore

  North Carolina State University

  13 shared

• Rebecca K Poole

  Mitchell Institute

  10 shared

• Jordan L. Cox-O'Neill

  North Carolina State University

  9 shared

• Molly Alexander

  North Carolina State University

  8 shared

• S. C. Loerch

  College of Wooster

  8 shared

Education

• Doctorate of Philosophy, Animal Science

  The Ohio State University

  2009

• Masters of Science, Animal and Poultry Sciences

  Virginia Polytechnic Institute and State University

  2005

• Bachelors of Science, Animal Science

  The Ohio State University

  2003