ACTIVE IMMUNIZATION AGAINST PROSTAGLANDIN-F2-ALPHA - EFFECT OF CONJUGATE DOSE AND BOOSTER INTERVAL ON ANTIBODY-TITERS AND ESTROUS BEHAVIOR IN POSTPUBERTAL BEEF HEIFERS
Ma. Crowe et al., ACTIVE IMMUNIZATION AGAINST PROSTAGLANDIN-F2-ALPHA - EFFECT OF CONJUGATE DOSE AND BOOSTER INTERVAL ON ANTIBODY-TITERS AND ESTROUS BEHAVIOR IN POSTPUBERTAL BEEF HEIFERS, Journal of animal science, 72(7), 1994, pp. 1778-1785
To optimize the prostaglandin Fa, (PGF) immunization protocol (conjuga
te [PGF-human serum albumin; PGF-HSA] dose and immunization regimen) t
o achieve prolonged suppression of estrous behavior (EB) in beef heife
rs, 56, 14-mo-old cyclic heifers were assigned (n = 7 per treatment) t
o eight treatments: 1) 3.3 mg of PGF-HSA on d 0 (single); 2) 3.3 mg of
PGF-HSA on d 0 and 28 (booster; B); 3) as (2) except on d 0 and 55; 4
) as (2) except on d 0 and 83; and 5 to 8) as in Treatments 1 to 4 exc
ept using 10 mg of PGF-HSA. The adjuvant was diethylaminoethyl-dextran
, and duration of the experiment was 170 d. Heifers were checked twice
daily for EB. A persistent corpus luteum (CL) was considered present
when progesterone (P-4) was greater than or equal to .5 ng/mL for 1 si
x consecutive samples (every 3 to 4 d). Data were analyzed using ANOVA
for a factorial plan. All heifers produced plasma antibody titers (sa
mples every 2 wk) against PGF (peak range: 7 to 84% binding at 1: 1,25
0). There were no effects (P > .10) of conjugate dose and no interacti
ons between dose and immunization regimen for any variable; therefore,
data were combined across dose. Mean and peak titers were greater (P
< .05) in heifers in 55- and 83-d B treatments than those in single im
munization and 28-d B treatments. Overall, 48/55 heifers formed a pers
istent CL (41/41 for B heifers). In the single, and 55- and 83-d B tre
atments, 23/42 heifers formed persistent CL in response to single/prim
ary immunization. There was no difference between immunization regimen
s in duration (133 +/- 4.4 d) of persistent CL. In summary, dose of co
njugate did not affect any variable; however, single immunizations wer
e,less effective in forming persistent CL and longer B intervals were
more effective in increasing antibody titers, but B interval did not a
ffect the incidence of persistent CL.