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Peripartum nutrition; dairy cattle; conception; semen type; hormones
This field trial tested the hypothesis that providing Kenyan smallholder dairy farmers with training and resources can enhance cows’ cyclicity and conception using conventional or sexed semen. One hundred farmers were randomly selected and randomly allocated to five equal-sized intervention groups: 1) reproduction only; 2) nutrition only; 3) reproduction and nutrition; 4) education only (quasi-control); or 5) nothing (control). Reproductive interventions included provision of prostaglandin F2? (PG) and/or gonadotropin-releasing hormone (GnRH) to induce estrus, and reproduction education. Nutrition interventions included provision of leguminous shrubs and nutrition education. At monthly visits over 17 months, farm and cattle data were collected, and open cattle underwent physical and reproductive exams to determine readiness for farmer decisions on sexed semen utilization. Cox proportional hazards modeling (CoxPH) was used to determine if intervention group was significantly associated with risk of conception. The final dataset included 191 cows and 26 heifers. Lowest and highest heat submission percentages were 8.5% and 35.5% in the control and reproduction groups, respectively. Conception percentages in cows and heifers were 44.0% and 54.5% for sexed semen and 72% and 79% for conventional semen, respectively. In the final multivariable CoxPH model, each unit increase in average body condition score was associated with 3.5 times higher risk of conception. Cattle that were inseminated following spontaneous heat had 1.8 times higher risk of conception over cows that were inseminated following a hormone-induced heat. In a significant interaction variable, when cows were supplemented with dairy meal in the last month of gestation, a higher risk of conception was achieved in cows on groups where leguminous shrubs were fed compared to groups where no leguminous shrubs were fed. This study concludes that focused effort on improving reproduction through education, hormone use and improved nutrition can improve heat submission and conception percentages on Kenyan smallholder dairy farms.