Lactic acidosis in cattle: efficiency of prophylactic feed additives and treatments for lameness arising from this disease

Abstract

Considering the importance and the economic losses caused by ruminal lactic acidosis and laminitis this research project aims to conduct two studies which aim to assess the prophylactic alternatives to acidosis and treatment for lameness in beef cattle that will contribute to improving the health of national herds. The Experiment 1 aims to comparatively assess the effectiveness of the antibiotic virginiamycin and monensin ionophore in the prevention of acute ruminal lactic acidosis in cattle. 24 cattle, male, fitted with rumen cannula, weighing 300 kg will be used. The animals will receive calculated basal diet at 2.7% of body weight (BW) (75% MS coast-cross hay and 25% concentrate). The 24 animals are randomly distributed according to weight into four groups of six animals each, as follows: control (C); virginiamycin (V); Monensin (M); + virginiamycin and monensin (MV). The control group will receive only the basal diet while the V group will receive virginiamycin and the M group will receive monensin; the MV group will receive the two additives. The doses of monensin and virginiamycin are 187.5 and 300 mg/animal/day, respectively. After 30 days of fed the additives an experimental lactic acidosis will be induced in all animals by the administration of sucrose. The animals will be clinically assessed at the following times: zero (baseline) and after three, six, 12, 18 and 24 hours of induction Alra. Samples of rumen fluid urine and blood will be collected. The following variables will be evaluated ruminal pH, redox potential, L lactate, osmolarity. Urine pH and specific gravity of the fluid will also be evaluated. Be determined in the blood cell volume, L-lactate, deficit of plasma volume, osmolality, pH, bicarbonate concentration, base excess and pCO2. The Experiment 2 aimed to evaluate the efficacy and side effects of three non-steroidal anti-inflammatory drugs (flunixin meglumine, ketoprofen and meloxicam) in the treatment of acute laminitis after induction of ruminal acidosis by excess of oligofructose. 32 cannulated cattle, which will go through an adjustment period of three days receiving 1.7 g / kg BW per day of oligofructose and subsequently be induced to frames Alra by administering a solution containing 17g / kg BW of oligofructose are used. After induction, when the animals show lameness score e 2 will be allocated in the following treatments: Control - receive 8 ml of isotonic saline; Flunixin - receive 2.2 mg / kg flunixin meglumine; Ketoprofen - receive 3 mg / kg ketoprofen; Meloxicam - receive 0.5 mg / kg of meloxicam. The treatments are intravenously with repeat dosing every 24 hours, except for meloxicam group receive a second dose 48 hours after the first. Blood collection will be held in ruminal fluid, clinical and orthopedic examination in the adaptation period (T-72, T-48, T-24), before induction with oligofructose (T0) and the period of observation after induction (the every 12 hours for 3 days) and after treatment with NSAIDs at the following times: T12h T24h, T32h, T48h, T60h, T72h, T84h T96h and after induction of Alra. Samples of rumen fluid are used to determine pH, redox potential, L lactate and osmolarity as the blood samples will be used for blood gas, blood count, cortisol, substance P, D and L lactate, matrix metalloproteinase 9, pepsinogen and biochemical analyzes. Stool samples will be collected for occult blood. Animals that after induction of cell volume Alra have higher than 42% will receive further treatment in order to reverse this situation. (AU)