PSXI-1 Agent-based simulation model to evaluate the technical performance of reproductive programs in beef cattle. (30th November 2020) - Ojeda-Rojas, Oscar Alejandro
Abstract: A stochastic, agent-based simulation model was created to compare the technical performance of reproductive strategies in beef cattle. The model was parameterized using field data and peer-reviewed scientific literature using AnyLogic software. Ten scenarios were evaluated: natural mating (NM) only (ONM); one timed artificial insemination (TAI) plus NM (1TAI+NM); two TAI plus NM, with 24, 32, and 40 days of interval between TAI (2TAI/24+NM, 2TAI/32+NM, and 2TAI/40+NM, respectively); three TAI without NM, with 24, 32, and 40 days of interval between TAI (3TAI/24, 3TAI/32, and 3TAI/40, respectively), and three TAI plus NM, with an interval between TAIs of 24 (3TAI/24+NM) and 32 days (3TAI/32+NM). The size of the female herd was up to 400 individuals. The bull population was 0, 7, or 15 bulls depending on the scenario used. The outcomes were assessed on 320 farms, using a 5, 000-day time horizon at one-day time intervals and an animal-by-animal basis. The 3TAI/24+NM resulted in a higher number of births (293 births) and weaned calves (287 calves), while the ONM had the lowest number of births (207 births) as well as weaned calves (203 calves). The heaviest and lightest males at weaning belong to the 3TAI/24 (190.58 ± 0.77 kg) and ONM (166.59 ± 0.93 kg), respectively. The total pregnancy rate was highest in 3TAI/24+NM (0.90 ± 0.00) and lowest for ONM (0.61 ± 0.01). The ONM reach 50% of pregnancy 52.5 days longer when compared to the scenarios that included TAI. Our model accurately represents the main interactions of a real beef cattle herd, with all the advantages of a physical experiment without incurring significant money expenses or alterations to the system. This study suggests that scenarios with three TAI accompanied by early pregnancy diagnosis presented better technical performance and produced more and heavier calves.