Decreased periparturient transmission of bovine leukosis virus in colostrum-fed calves.
BACKGROUND
The relation between calf bovine leukosis virus (BLV) infection status and colostrum ingestion is unclear. Two conclusions have been drawn from previous studies. One suggests that colostrum ingestion transmits BLV to neonatal calves. The second suggests that colostral antibodies are protective.


OBJECTIVE
Colostrum from BLV-positive cattle is protective in naturally exposed calves.


METHODS
Twelve colostrum-deprived Holstein calves and 20 colostrum-fed Holstein calves born to BLV-infected cows.


METHODS
Prospective study. Colostrum-deprived calves were tested weekly by enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) tests for BLV antibody and provirus for 12 weeks or until the animal became positive for BLV infection. Colostrum-fed calves were fed colostrum derived from BLV-positive cows. Thereafter, ELISA and PCR tests for BLV antibody and provirus were performed every other week until 2 consecutive negative ELISA tests or 1 positive PCR test was achieved. The proportion of calves that converted to BLV-positive status was calculated for each group and compared between groups by using the Fisher exact test.


RESULTS
Four of 12 colostrum-deprived calves (33%) became BLV positive, whereas 0 of 20 colostrum-fed calves (0%) became BLV positive. The proportion of calves that became infected was significantly higher in the colostrum-deprived group (P = .014).


CONCLUSIONS
Calves born to BLV-positive cows are exposed during parturition, and a proportion of these calves will become infected with BLV. Administration of colostrum from BLV-positive cows greatly decreases the risk of infection.
Nagy
Dusty W
DW
Departments of Veterinary Medicine and Surgery, University of Missouri-Columbia, Columbia, MO 65211, USA. nagyd@missouri.edu
Tyler
Jeff W
JW
Kleiboeker
Steven B
SB
D000818:Animals; D000831:Animals, Newborn; D000914:Antibodies, Viral / Q000097:blood; D002417:Cattle; D003126:Colostrum / Q000276:immunology* / Q000821:virology; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D016583:Enzootic Bovine Leukosis / Q000276:immunology* / Q000635:transmission* / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D015994:Incidence; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary*; D001909:Leukemia Virus, Bovine / Q000235:genetics / Q000276:immunology*; D008297:Male; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011247:Pregnancy; D011446:Prospective Studies; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics
D000914:Antibodies, Viral; D004279:DNA, Viral; D014759:Viral Envelope Proteins