University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 5-2012 Improving Beef Cattle Performance on Tall Fescue Brian Thomas Campbell [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Animal Sciences Commons Recommended Citation Campbell, Brian Thomas, "Improving Beef Cattle Performance on Tall Fescue. " PhD diss., University of Tennessee, 2012. https://trace.tennessee.edu/utk_graddiss/1277 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Brian Thomas Campbell entitled "Improving Beef Cattle Performance on Tall Fescue." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Animal Science. John C. Waller, Major Professor We have read this dissertation and recommend its acceptance: F. David Kirkpatrick, Gina M. Pighetti, Gary E. Bates, Cheryl J. Kojima Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Improving Beef Cattle Performance on Tall Fescue Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Brian Thomas Campbell May 2012 I Abstract The overall goal of the studies described in this dissertation was to improve beef production of cows grazing endophyte infected tall fescue either through management practices or through identifying markers for genetic selection. Experiment 1 investigated differences in spring and fall calving herds grazing endophyte infected tall fescue. This study determined that managing for a fall calving beef herd is the more productive and efficient system. This is due to increased reproductive efficiency as well as traditionally greater market prices at the time of weaning. A spring calving system will have faster growing calves, but the increased weight of the calves is not enough to offset the added value of more calves produced in the fall calving herd. Experiment 2 was a study to validate a single nucleotide polymorphism (SNP) as a potential genetic marker found on the DRD2 gene. Steers with an AA genotype at this SNP have been shown to have greater prolactin levels and this study indicated that cows which have the AA genotype will have their first calf an average of 23 days earlier than cows with the GG genotype. Also when allelic frequency was examined it was shown that spring calving cows had a shift in allelic frequency away from Hardy-Weinberg equilibrium towards the A allele. Experiment 3 used a genome wide association study (GWAS) to confirm the presence of other SNPs that may be used as markers for resistance to tall fescue toxicosis in beef cattle. Twenty four SNPs were identified with nine SNPs associated with birth weight and 15 associated with weaning weight. Some of the SNPs are found within genes associated with production and carcass traits such as average daily gain, acid detergent fiber intake, marbling, and fat thickness. The II results of this study are very promising but more research needs to be completed. The SNPs that have been identified need to be validated. III Table of Contents Introduction ............................................................................................................. 1 Literature Review .................................................................................................... 6 Tall Fescue .................................................................................................... 7 Fat Necrosis ................................................................................................... 8 Fescue Foot ................................................................................................... 9 Tall Fescue Toxicosis .................................................................................. 10 Vasoconstriction........................................................................................... 11 Serum Prolactin ........................................................................................... 12 Reproduction in Females ............................................................................. 13 Reproduction in Males ................................................................................. 15 Alleviation of Tall Fescue Toxicosis ............................................................. 16 Non-Infected Plants ..................................................................................... 17 Novel Endophytes ........................................................................................ 18 Overseeding ................................................................................................ 19 Dopamine Antagonists ................................................................................. 20 Calving Season ............................................................................................ 20 Genetic Resistance ...................................................................................... 22 Genome Wide Association Study................................................................. 25 Summary ..................................................................................................... 27 A Comparison of Spring and Fall Calving Beef Herds Grazing Endophyte Infected Tall Fescue.............................................................................................. 30 IV Abstract ........................................................................................................ 31 Introduction .................................................................................................. 33 Materials and Methods ................................................................................. 34 Results and Discussion ................................................................................ 37 Conclusions ................................................................................................. 46 Literature Cited ............................................................................................ 47 Appendix: Tables and Figures ..................................................................... 50 A Single Nucleotide Polymorphism in the Dopamine Receptor D2 Gene May be Informative For Resistance to Fescue Toxicosis in Angus-Based Cattle .. 60 Abstract ........................................................................................................ 61 Introduction .................................................................................................. 63 Materials and Methods ................................................................................. 64 Results and Discussion ................................................................................ 69 Literature Cited ............................................................................................ 74 Appendix: Figures and Tables ..................................................................... 77 A Discovery of Genetic Markers for Resistance to Tall Fescue Toxicosis in Angus-Based Cattle .............................................................................................. 84 Abstract ........................................................................................................ 85 Introduction .................................................................................................. 87 Materials and Methods ................................................................................. 88 Results and Discussion ................................................................................ 91 Conclusions ................................................................................................. 92 Literature cited ............................................................................................. 94 V Appendix: Tables and Figures .................................................................... 96 Conclusions ........................................................................................................ 100 Literature Cited ................................................................................................... 104 Vita ....................................................................................................................... 115 VI List of Tables Table 1.1. Standard age of dam adjustment factors (kg) for adjusted birth weight and adjusted 205-day weaning weight .................................................................... 50 Table 1.2. Least squares means for calving interval, days to weaning and days to first calf ............................................................................................................... 50 Table 1.3. Least squares means for birth weight, weaning weight, and average daily gain ................................................................................................................. 51 Table 1.4. Sample budget for raising a replacement heifer from weaning to first calf .........................................................................................................................