Location: Livestock Issues Research
Project Number: 3096-32000-009-038-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Apr 1, 2023
End Date: Mar 31, 2026
Objective:
The objective of this proposal is to determine the effect of a combination of supplements on the incidence and severity of liver abscesses.
Approach:
To accomplish the aforementioned objective, 40 weaned dairy or dairy x beef steer calves (~200 lbs.;~150 days of age) will be. Calves will be randomly assigned to 1 of 3 treatments: 1) Control (CON; n=10), in which calves will be cycled on an acidotic diet, 2) TRT A in which calves will be cycled on an acidotic diet and supplemented daily with CLOSTAT (13 g/hd/d) and Villitech (3 g/hd/d; n=15) or 3) TRT B ( n=15) in which calves will be cycled on an acidotic diet and supplemented daily with CLOSTAT (13 g/hd/d), Villitech (3 g/hd/d), and red clover (30 g/hd/d). Upon arrival, a body weight will be collected, individual identification will be provided, and anthelmintic will be provided, and metaphylactic antibiotics will be administered (tildipirosin; Zuprevo; Merck Animal Health). Each day, an observer will monitor and record a health score and a fecal score to evaluate clinical signs of illness and fecal consistency, respectively. Within the first week of arrival, a pH monitoring bolus (Wolfhound Analytics) will be inserted in as many calves as loggers are available to monitor pH at 15 minutes intervals for the duration of the study. Feed disappearance will be recorded daily. Body weight, rectal temperatures, and pen cleaning will occur approximately every 7 days for the duration of the study.
On d 0, calves will be taken off their basal diet and fed an acidotic diet (formula in spreadsheet). Calves will be fed the acidotic diet for 3 days, control diet for 2 days, and the cycle will be repeated 4 times. Boluses monitoring real-time pH will be evaluated prior to the morning feeding, and if a calf reaches a ruminal pH of less than 4.5 for greater than 4 h, the calf will be switched back to a control diet. Following the ration change cycles, all calves will be intra-ruminally administered Fusobacterium necrophorum (8L1 type A; target dose 1.0x1011CFU/mL in 100 mL reduced brain heart infusion broth), Salmonella enterica serotype Lubbock (liver isolate; target dose 1.0 x 109CFU/ml in 100 mL tryptic soy broth). Administration of the bacterial cocktail will occur via rumen tube, and the tube will be flushed with 100 mL phosphate buffered saline. Rumen fluid and a fecal sample will be collected immediately prior to bacterial inoculation to quantify the presence of Fusobacterium necrophorum present.
Blood will be collected on days 0, 14, 28, and 38, and serum and plasma will be isolated and stored for potential future analyses. Upon harvest, calves will be evaluated for liver abscesses and/or scarring along with gross pathological evaluation of the rumen, lungs, ileum, and colon. Abscesses will be cultured for Fusobacterium, Trueperella, and Salmonella spp. Histopathology samples will be collected from the rumen to evaluate the differences in architectural features between the treatments. Finally, F. necrophorum will be cultured from ruminal contents and epithelial tissue, colon contents and tissue, and any liver abscesses that develop.
