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ASSOCIATION OF GENETIC PRODUCTION INDEXES WITH PRODUCTION OUTCOMES OF FEEDLOT STEERS
No full textGenetic knowledge is increasingly utilized within the beef seedstock sector, yet uncertainty remains on how to maximize these inputs at the commercial level. The objectives of this study were to evaluate the effect of sorting natural and conventionally marketed fed beef cattle according to a genetic prediction index on performance and carcass traits, and determine the association of genetic indices to economically important production outcomes. The study hypothesis was that sorting beef cattle by genetic index would not influence the outcome of economically important traits. Two cattle sources were utilized, Angus and Angus × Hereford steers that did not receive growth promoting technologies or antimicrobials to comply with a natural marketing program (NAT; n=98; initial BW = 362 ± 11 kg) and Angus steers that were fed conventionally (CONV; n=81; initial BW = 364 ± 11 kg). Cattle were assigned to pens within source and stratified according to a feeder advantage (FA1) index from least to greatest by pen (NAT=10 steers/pen and 9 pens/treatment; CONV=10 or 11 steers/pen and 7 pens/treatment). All cattle were managed similarly and fed the same basal diet with the exception that NAT diets did not contain antimicrobial (monensin or tylosin) or growth promoting technologies (implants or beta-agonist). Individual cattle were harvested upon achieving a target shrunk (4%) BW of 635 kg. Genomic indices for WW and gain increased quadratically (P < 0.01) as the FA1 index increased for both cattle types. For conventionally finished cattle, genomic indices for heifer pregnancy (P ≤ 0.02) decreased whereas milk (P < 0.01), gain (P < 0.01), carcass weight (P = 0.03), marbling (P < 0.01), and ribeye area (P = 0.02) increased as the FA1 index increased. Daily dry matter feed offered (DDMFO) increased quadratically (P < 0.01) as FA1 index increased for both NAT and CONV. Within the NAT cattle, FA1 index was correlated to DOF (r = -0.39; P < 0.001), DDMFO (r = 0.35; P < 0.01), SUMDMO (r = -0.32; P < 0.01), day 0 BW (r = 0.30; P < 0.01), and ADG (r = 0.23; P < 0.05). Among CONV cattle, FA1 index was positively correlated (r = 0.44; P < 0.001) to DDMFO. The FA1 index score means did not differ (P = 0.08) amongst USDA QG’s, or USDA YG’s (P = 0.25). Numerically, NAT cattle in FA group 75 to 82 were greatest in HCW (P < 0.01), dressed yield (P < 0.01), and total carcasses value (P < 0.01). Net return carcass basis (P = 0.02) was numerically greatest for FA group 32 to 41
A Clinical Analysis of the Effect of Antibiotic Administration on the Neonatal Foal Microbiome
No full textABSTRACT
A study was conducted to investigate the effects of antibiotic administration on the neonatal foal microbiome, complete blood count (CBC), and fibrinogen (FIB) concentration. Eleven stock-type newborn foals were studied in the clinical setting. Foals were enrolled in the trial within 24 h of birth and administered treatments according to CBC, fibrinogen, and veterinary decision. Foals were treated with an antibiotic (amikacin and ceftiofur, amikacin and penicillin, or trimethoprim/sulfadiazine; n = 7), or not treated (n = 4). Foals that did not respond to the initial antibiotic treatment based on CBC, fibrinogen, and veterinary supervision were administered subsequent treatment (n = 3). The trial began January 2018 and ended September 2018, with each foal being enrolled from birth to at least 56-d of age. Fecal samples were collected from foals at d 0, 7, 14, 21, 28, and 56. When a foal experienced approximately 1 mo without treatment or at 56 d, whichever was earliest, a corresponding dam fecal sample was collected by the consulting veterinarian or trained staff. Blood was obtained on d 0, 7, 14, 21, 28, and 56 and analyzed using an automated hemocytometer (IDEXX ProCyte Dx Hematology Analyzer, IDEXX Laboratories, Westbrook, ME) to determine complete blood count variables. Blood serum was analyzed using an automated analyzer (IDEXX Catalyst Dx Chemistry Analyzer with an Equine 15 CLIP, IDEXX Laboratories), and fibrinogen was determined via IDEXX VetAutoread (IDEXX Laboratories). Fecal samples were submitted to a commercial laboratory (Molecular Research LP, in Shallowater, TX) for DNA sequencing and
microbiome analysis. There was no effect of treatment × day interactions for hematology parameters (red blood cell concentration, P = 0.86; white blood cell concentration, P = 0.69; neutrophils, P = 0.59; glucose, P = 0.43; and fibrinogen, P = 0.90). There was an effect of day observed on red blood cell concentration (P < 0.001), white blood cell concentration (P = 0.04), neutrophils (P = 0.03), and fibrinogen (P = 0.02). In addition, there was an effect of treatment (P = 0.02) on fibrinogen. Clostridia and bacteroidia were the most abundant bacteria found in fecal samples of the foal and dam pairs. There was no effect of treatment × day interaction on clostridia (P = 0.24) or bacteroidia (P = 0.35). However, there was a main effect for day (P < 0.001) noted for relative abundance of each bacterium. Although present in very small amounts (< 1%), fibrobacteria was the only class of bacteria to result in an effect of treatment × day interaction (P = 0.05). Bacterial flora became more diverse and similar to the matched dam sample after the completion of any antibiotic treatment. Further research is needed to determine the role specific antibiotics play in the neonatal foal and if antibiotic use has any affects that might carry into adult life. In addition, continued microbiome studies could lead to microbiome analysis being involved in diagnostics
