REDUCTION OF THE VOLUNTARY WAITING PERIOD BY USE OF HORMONAL PROTOCOLS AND FIXED-TIME ARTIFICIAL INSEMINATION (FTAI) IN DAIRY COWS (original) (raw)

The aim of this study was to reduce the interval calving-conception in dairy cows by administration of two different hormonal protocols for estrus synchronization and fixed-time artificial insemination (FTAI). Holstein dairy cows (n=128) were divided in three groups (G): G1 (44 treated), G2 (34 treated) and G3 (50 as control). In the treated cows the following hormonal protocols were applied between 40 and 45 days post partum: G1-Day 0 (D0) -bovine intravaginal device containing progesterone (P 4 ) plus 1.0 mg of estradiol benzoate (EB), D8 -removal of the P 4 , plus 0.5 mg of cloprostenol plus 400 IU of equine chorionic gonadotropin (eCG), D9 -1.0 mg of EB and FTAI after 36 hours. G2 -D0 -P 4 intravaginal device plus 50 mcg of gonadotropin-releasing hormone (GnRH), D7 -removal of the P 4 plus cloprostenol plus 400 IU eCG; D9 -50 mcg of GnRH and FTAI 16 hours after. G3 -Control group inseminated 12 hours after the visual estrus. Results: G1 and G2 were inseminated (FTAI) respectively in the D55.5±0.9 and D56.8±1.3 after calving, while the G3 in the D84.5±5.7 (p<0.05). The pregnancy rate in the G1, G2 and G3 was respectively 47.0, 46.1 and 35.8% (p>0.09). In conclusion: there was significant reduction of the interval calving/conception in treated cows (G1,G2)(p<0.05) and better pregnancy rate regarding to G3 Key Words: interval post partum period; pregnancy rate; dairy cows; progesterone; time artificial insemination Reduction of the interval calving-conception by use of hormonal protocols and fixed-time artificial insemination in dairy cows