title: Fertility on synchronized estrus in crossbred (Bos taurus x Bos indicus) heifers.
abstract: This study was performed in Western Maharastra (India). The 272 crossbred heifers were randomly allocated within herds to one of the four following groups: 1) silastic coils, 10 days treatment (n = 65); 2) Norgestomet implants, 10 days treatment (n = 71); 3) prostaglandin F(2alpha) two injections 11 days apart (n = 70); and 4) control (n = 66). Almost all heifers in the treated groups were detected in heat during the four days following treatment (88-100%) vs 26% in the control group in the first 21 days. Mean conception rates at first AIs were respectively 62,48 and 60% in groups 1,2 and 4 (p > 0.05) and only 29% in group 3. By 90 days after treatment, 66, 59, 46 and 33 per cent of the females were pregnant for groups 1 to 4, respectively (p < 0.001). In conclusion, progestogen treatments seemed to be highly satisfactory both in terms of conception rates and intervals from treatment to pregnancy.
authors.affiliation: Bharatiya Agro-Industries Foundation, Uruli-Kanchan, Pune, 412202, India.
authors.forename: S M
authors.initials: SM
authors.lastname: Lokhande
authors.forename: V H
authors.initials: VH
authors.lastname: Patil
authors.forename: D C
authors.initials: DC
authors.lastname: Mahajan
authors.forename: Y P
authors.initials: YP
authors.lastname: Phadnis
authors.forename: P
authors.initials: P
authors.lastname: Humblot
authors.forename: M
authors.initials: M
authors.lastname: Thibier