Synchronization with two doses of PGF2α in dry Hereford cows and Hereford and Holstein heifers

Abstract

The purpose of this work was to determine if a reduced dose (200µg) of a prostaglandin F2α (PF2α) analog (Delprostenate), intramuscularly, can obtain reproductive results similar to that recommended by the laboratory (800µg). Three experiments (E) were performed in a commercial establishment. The EI used dry cows of different ages, of the Hereford (He) breed, and the 2-year-old EII and III heifers He and Holando, respectively. In IE and IBD, the injected bellies were between days 5 to 20 of the estrous cycle (day 0 = heat). The IBD was performed with two injections of PF2α with a difference of 11 days, the first corresponding to the commercial dose (800µG) and the first one corresponding to the commercial dose (800µG). Second to the experimental treatments (800µg or 200µg). The percentages of heat after 6 days post-treatment (% C) and of no return until 32 days of artificial insemination (% NR), for the highest and lowest dose of PF2α were the following: EI, in% C, 100 (n = 15) against 93 (n = 14) and in% NR 67 against 70; IBD, in% C, 89 (n = 19) against 100 (n = 18) and in% NR 70 against 72; in IBD, in% C, 80 (n = 10) versus 90 (n = 10) and% NR, 87 versus 100, respectively. There were no differences (P> 0.05) between the treatments in any of the 3 experiments for the two variables analyzed. The experimental data available to date supports the recommendation for the use of the 200µg dose.