Artificial insemination of indigenous Nigerian Zebu cattle following synchronization of oestrus with prostaglandin F 2α: I. Preliminary fertility trial

Abstract

The fertility of indigenous Nigerian cattle (Zebu) to artificial insemination (AI) following various oestrus synchronization regimes and naturally occurring oestrus was studied. One hundred and thirty cows were assigned to six treatment groups: 1. controls, inseminated at the naturally occurring oestrus; 2. AI at observed PGF 2α-induced oestrus; 3. Timed AI at 72 h post-second PGF 2α injection; 4. Timed AI 84 h post-second PGF 2α injection; 5. Timed AI at 96 h post-second PGF 2α injection; and 6. Timed dual AI at 72 and 96 h post-second PGF 2α injection. Pregnancy rate (PR) — calculated as the number of pregnant cows divided by the number of cows assigned to treatment group and expressed as a percentage-were 23·3, 30·0, 15·0, 15·0, 35·0 and 35·0 percent for groups one to six respectively. The conception rate (CR) — calculated as the number of pregnant cows divided by the number of cows detected in oestrus and inseminated and expressed as a percentage — were 46·7, 50·0, 23·1, 20·1, 46·7 and 53·9 percent for groups one to six respectively. AI at observed oestrus, or double AI at 72 and 96 h post injection gave best fertility rates following synchronization of oestrus with PGF 2α. The investigation also highlights the need for further investigations with a view to determining the optimum time(s) for predetermined AI following PGF 2α treatment.