Do. Rae et al., REPRODUCTIVE-PERFORMANCE OF BEEF HEIFERS - EFFECTS OF VULVO-VAGINITIS, UREAPLASMA-DIVERSUM AND PREBREEDING ANTIBIOTIC ADMINISTRATION, Theriogenology, 40(3), 1993, pp. 497-508
A group of 450 heifers, 13 to 15 mo of age, were individually identifi
ed, vaccinated (IBR, PI3, Leptospira, Campylobacter fetus), examined (
body condition score, reproductive tract evaluation, assessment of vag
inal lesions), and cultured for U. diversum. Heifers were randomly all
ocated to either a treated group given chlortetracycline (approximatel
y 350 mg/hd/d for 30 d in a grain crumble) or a nontreated control gro
up. Prebreeding, most heifers showed signs of vulvovaginitis, 44% cult
ured positive for U. diversum. Significant associations were found bet
ween the severity of vaginal lesions and ovarian activity (P < 0.05),
and between BCS and ovarian activity (P < 0.02). The U. diversum vagin
al culture (positive or negative) showed no significant association wi
th BCS, severity of vaginal lesions, or ovarian activity (all were P >
0.5). At pregnancy examination (35 d following conclusion of a 61-d b
reeding season), treated compared with nontreated heifers showed 1) a
slight but not significant (P> 0.25) decrease in vaginal colonization
by U. diversum (46 to 34% and 41 to 37%, respectively); 2) an associat
ion between increased severity of vaginal lesions and increasing pregn
ancy rate, especially in treated heifers; and 3) an increased pregnanc
y rate (72 and 57%, respectively; P< 0.01). Prebreeding treatment with
chlortetracycline appeared to improve pregnancy rates in beef heifers
with endemic U. diversum infections, although the role of U. diversum
in heifer fertility is still not clear.