Reproductive patterns of Santa Gertrudis heifers in Morocco: II. Fertility of cyclic and acyclic heifers after synchronization of estrus

Reproductive performances were compared in cyclic and acyclic Santa Gertrudis heifers using different synchronization programs. Regimens tested were DGF2α vs SMB in cyclic heifers and SMB vs SMB/PMSG in acyclic heifers. Two groups of cyclic and acyclic heifers were not treated and served as control. Estrous responses to treatment were low in PGF2α-treated cyclic heifers (61%) and SMB-treated acyclic heifers (60%); but higher in SMB-treated cyclic heifers (89%) and SMB/PMSG-treated acyclic heifers (75%). Single appointment insemination (80 ± 2 hours for PGF2α and 48 ± 2 hours for SMB) resulted in higher pregnancy rates in SMB-treated cyclic heifers and SMB/PMSG-treated acyclic heifers (43%) than in PGF2α-treated cyclic heifers (21%) or SMB-treated acyclic heifers (20%). Pregnancy rates after 90 days of breeding were not statistically different among control (53%) and treated animals in cyclic heifers (PGF2α, 54% and SMB, 57%), but acyclic SMB/PMSG-treated heifers had a higher pregnancy rate by 90 days (86%) than did the control (46%) and SMB-treated heifers (47%). It was found that reproductive performance in heifers under range conditions could be improved using SMB/PMSG treatment in acyclic heifers, and could help in getting more heifers pregnant early in the breeding scason.