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Reproductive performance, early progeny wastage, and cervix response using fixed-time intrauterine or transcervical insemination or natural service following synchronization of estrus and ovulation in goats

Loetz Urquiola, Erick R.
Scope and Method of Study:
Assisted reproductive technologies provide necessary tools for improving farm revenue. Hormonal estrus and ovulation synchronization, while decreasing costs of production and allowing for economies of scale advantage, reduce reproductive efficiency. A randomized experimental prospective field and clinical trial using ultrasound imaging was conducted to determine the effect of estrus/ovulation synchronization protocol on goat reproductive performance, prenatal and perinatal losses, and cervix response of dairy, meat and fiber production phenotypes using fixed-time insemination by different breeding procedures.
Findings and Conclusions:
Compared to natural service most reproductive efficiency traits used to describe goat reproductive performance were negatively influenced by the assisted reproductive technologies implemented. When hormonal estrus/ovulation synchronization protocols are used in conjunction with fixed-time breeding initial acceptable conception rates are reduced by time of parturition, hence kidding rates are lower across breeds, ages, and parity categories. The decrease in reproductive performance is mainly due to short P4 exposure combined with fixed-time breeding rather than concurrent use of eCG and hCG, although the use of the chorionic gonadotropins resulted in high early progeny wastage particularly embryonic mortality. Goats displayed a pattern of early rather than late progeny loss. Prenatal losses were influenced by: breed, age and time of exposure to P4. Increased prenatal losses were influenced by breeding procedures particularly excessive manipulation during trans-cervical artificial insemination. Short P4 exposure increased breeding time investment, made less likely to traverse the cervix, and thus influenced the site of semen deposition. The use of real-time ultrasound imaging for pregnancy diagnosis at 45 days post-breeding resulted in high sensitivity, accuracy, and precision. However, the technology was not reliable to establish the number of embryos in non-tractable goat production phenotypes and/or parity categories under field conditions.