Improving conception rate in lactating dairy cows by using modified ovsynch protocol during summer

Abstract

The aim of this study was to test two different timed artificial insemination (AI) protocols in order to improve the percentage of pregnant cows per AI in lactating dairy cows during the summer. Cows (n=140) were randomly divided into two groups; cows in the OVS group (n=75) received the Ovsynch protocol (GnRH–7d–PGF2α–2d–GnRH–16h–AI), and cows in the MOVS group (n=65) received the Ovsynch protocol with exogenous progesterone (P4) which administrated between GnRH and PGF2α. In addition, GnRH was injected 7 d after AI in the MOVS group (GnRH–P4–7d –PGF2α–2d–GnRH–16h–AI–7d–GnRH). Response to the second GnRH treatment of Ovsynch (GnRH-2) was greater (P<0.03) in the MOVS (98.5%) than the OVS (89.3%) group. Although P/AI at 31 d was numerically greater in the MOVS (46.2%, 30/65) than the OVS (37.3%, 28/75) group, this difference was statistically insignificant. Thus, because of the greater response to GnRH-2 and P/AI in MOVS compared with the OVS group, the MOVS protocol can be used to improve P/AI in lactating dairy cows during the summer, but further studies are needed to be evaluated the effects of the MOVS protocol on P/AI during the summer.The aim of this study was to test two different timed artificial insemination (AI) protocols in order to improve the percentage of pregnant cows per AI in lactating dairy cows during the summer. Cows (n=140) were randomly divided into two groups; cows in the OVS group (n=75) received the Ovsynch protocol (GnRH–7d–PGF2α–2d–GnRH–16h–AI), and cows in the MOVS group (n=65) received the Ovsynch protocol with exogenous progesterone (P4) which administrated between GnRH and PGF2α. In addition, GnRH was injected 7 d after AI in the MOVS group (GnRH–P4–7d –PGF2α–2d–GnRH–16h–AI–7d–GnRH). Response to the second GnRH treatment of Ovsynch (GnRH-2) was greater (P<0.03) in the MOVS (98.5%) than the OVS (89.3%) group. Although P/AI at 31 d was numerically greater in the MOVS (46.2%, 30/65) than the OVS (37.3%, 28/75) group, this difference was statistically insignificant. Thus, because of the greater response to GnRH-2 and P/AI in MOVS compared with the OVS group, the MOVS protocol can be used to improve P/AI in lactating dairy cows during the summer, but further studies are needed to be evaluated the effects of the MOVS protocol on P/AI during the summer.