Evaluation of an inactivated Neospora caninum vaccine in beef feedlot steers.
OBJECTIVE
To evaluate effects of vaccination of feedlot steers against bovine neosporosis on weight gain, feed intake and efficiency (feed intake per gain), and carcass characteristics.


METHODS
Longitudinal observational study.


METHODS
60 weaned Brangus steers seronegative for Neospora caninum.


METHODS
Steers were assigned to age-matched control and treatment groups. Steers in the treatment group received N. caninum vaccine on days 79 and 106, while control steers received 2 placebo injections. For each steer, serologic status for N. caninum was determined on days 0 (weaning), 51, 79, 106, 135, 163, 191, 219, and 247 by use of an ELISA; body weight was determined on the same days and at slaughter (day 259). Daily feed intake per steer was measured from days 79 to 259.


RESULTS
Seroconversion occurred in 23 of 30 (76.7%) steers in the vaccinated group. Immediately after vaccination, average daily gain, average daily feed intake, and feed efficiency were significantly greater in the treatment group than in the control group, but these differences did not persist. No differences between groups were found in regard to live weight at slaughter, hot carcass weight, dressing percentage, or quality grade; however, steers in the vaccinated group had significantly lower yield grades than did control steers.


CONCLUSIONS
In feedlot steers, use of this vaccine against N. caninum was safe and did not affect overall feedlot performance or meat quality; effects on yield grade require further evaluation.
Barling
Kerry S
KS
Department of Large Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4475, USA.
Lunt
David K
DK
Graham
Sherry L
SL
Choromanski
Leszek J
LJ
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D002417:Cattle / Q000254:growth & development*; D002418:Cattle Diseases / Q000517:prevention & control*; D003048:Coccidiosis / Q000517:prevention & control / Q000662:veterinary*; D002149:Energy Intake; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D008137:Longitudinal Studies; D008297:Male; D008460:Meat / Q000592:standards; D018688:Neospora / Q000276:immunology*; D016052:Protozoan Vaccines / Q000008:administration & dosage; D011897:Random Allocation; D012449:Safety; D014611:Vaccination / Q000662:veterinary; D015164:Vaccines, Inactivated / Q000008:administration & dosage; D015430:Weight Gain
D000913:Antibodies, Protozoan; D016052:Protozoan Vaccines; D015164:Vaccines, Inactivated