Mar 4, 2016 - 4University of Florida, North Florida Research and. Education Center ... A&M University, Canyon, TX, 3Texas Tech University,. Department of ...
Published March 4, 2016
068 Utilization of resynchronization as a strategy to increase the percentage of replacement beef heifers conceiving to artificial insemination (AI) after an initial fixed-time AI (TAI).
069 Yeast probiotic supplementation mitigates some of the negative effects of heat stress in feedlot heifers.
P. L. P. Fontes*1, N. Oosthuizen1, V. R. G. Mercadante2, G. V. de Moraes3, D. D. Henry4, F. M. Ciriaco4, N. DiLorenzo1, G. C. Lamb1 University of Florida, Marianna, FL, 2Virginia Polytechnic Institute and State University, Blacksburg, VA, 3State University of Maringa, Maringa, Brazil, 4 University of Florida, North Florida Research and Education Center, Marianna, FL 1
P. R. Broadway*1, J. A. Carroll1, N. C. Burdick Sanchez1, S. L. Roberts2, K. P. Sharon3, J. T. Richeson2, J. R. Corley4
1
USDA-ARS, Livestock Issues Research Unit, Lubbock, TX, 2Department of Agricultural Sciences, West Texas A&M University, Canyon, TX, 3Texas Tech University, Department of Animal and Food Sciences, Lubbock, TX, 4Phileo Lesaffre Animal Care, Cedar Rapids, IA
Heat stress (HS) in feedlot cattle can be detrimental to performance, health and profitability; however, utilization of feed additives has the potential to mitigate some of these negative effects. Therefore, this study was designed to determine if supplementation of a combination live yeast and yeast cell wall product in feed could mitigate the negative impacts associated with HS. Crossbred, phenotypically similar beef heifers (n=32; BW=385±43 kg) were divided into 2 pens in which one pen was fed a standard finishing ration (CON), and the other was fed the same ration plus supplemented via top dress with a combination of a live yeast (1.5 g/hd/d) and yeast cell wall product (2.5 g/hd/d; YEAST; Phileo Lesaffre Animal Care, Milwaukee, WI). After 50 d of supplementation, cattle were transported to an environmentally controlled facility and placed in individual stanchions where indwelling jugular catheters and vaginal temperature (VT) loggers were inserted. Heifers were kept in thermoneutral (TN) conditions for 48 h (temperature-humidity index ~67; THI) then were subjected to HS for 4 d (THI~80). From d 2 to 6, hourly blood samples were collected for serum isolation from 1400-1800 h and again from 2200-0200 h which represented the targeted peak and nadir of THIs over the 5-d period. A whole blood sample was collected twice daily at 1400 and 2200 h for complete blood counts (CBC). Data collected included BW, water intake, respiration rate (RR; measured at 1600 and 2400 h daily) and serum cortisol, glucose and NEFAs. There was no change in BW (P=0.14) or ADG (P=0.53) between the treatments during the heat stress. Yeast supplemented heifers exhibited decreased VT during HS (P
