Strategies to Improve Fertility and Reproductive Efficiency of Dairy and Beef Cattle Using Modified Timed Artificial Insemination Breeding Protocols
For producers to maintain long-term profitability and ensure economic growth, they must "invest in their future - invest in their heifers. Heifers represent the most advanced genetics in the herd. Therefore, the genetic merit of AI-sired calves from heifers is superior to that of AI-sired calves from older cows. At least, as far as dairy production concerns nearly one-third of a herd's genetic and economic potential is at risk due to the use of natural service sires on heifers and lack of research regarding dairy heifer reproduction. Therefore research in the area of systematic breeding program, which enhances reproductive efficiency and use of AI in heifers, is essential for growth of prosperity of animal agriculture. This proposal addresses the questions: "Does GnRH given at the same time of CIDR insertion improve fertility following timed AI"
The greater economic impact on the beef operation is that heifers that conceive to AI have decreased dystocia at first calving, and are longer postpartum when bred for the second calf ; resulting in increased fertility. Moreover, data indicates that AI sired cows are produce greater income than cows that are products of natural service. Heifers that conceived the earliest immediately indicated their greater productive efficiency and lifetime production potential. Beef heifers that calve by 2 yr of age have greater lifetime production efficiencies than heifers that calve at older ages. In a conservative estimate beef cows that conceive early in the breeding season would produce calves that weigh more at weaning because they are older. At 2.0 lb/day calf growth and $1.10/lb beef value, a calf that is one day older at weaning brings an additional $2.20. A calf conceived on the first day of
a 30-day breeding season would be worth $66.00 more than one conceived on the last day. If the proposed modified synchronization protocol improves the conception rate by 10% in cows artificially inseminated on the first day of breeding season, this would generate a financial benefit of ~$2000 in a 300-cow herd.