An agent-based simulation model to evaluate the technical, economic and financial performance of reproductive technologies in beef cattle

• Ano de defesa: 2020
• Autor(a) principal: Rojas, Oscar Alejandro Ojeda
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Doppler; Inseminação artificial em tempo fixo; Pregnancy; Prenhez; Ressincronização; Resynchronization; Simulação; Simulation; Timed artificial insemination
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/10/10135/tde-14052020-133823/

The objective of this study was to create a stochastic, agent-based simulation model that allows to compare the technical and economic performance of reproductive strategies on a synthetic population of beef cattle. The model was created using the AnyLogic simulation tool and was parameterized using data from a real beef cattle herd and from peer-reviewed scientific literature. 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 between inseminations (2TAI/24+NM, 2TAI/32+NM, and 2TAI/40+NM, respectively); three TAI without NM, with 24, 32, and 40 days between inseminations (3TAI/24, 3TAI/32, and 3TAI/40, respectively), and three TAI plus NM, with an interval between inseminations of 24 (3TAI/24+NM) and 32 days (3TAI/32+NM). NM started 10 days after the last insemination and was performed until the end of the breeding season. The initial population of the model ranged between 400 and 415 animals, depending on whether NM was used or not. The size of the female herd was fixed to contain 400 individuals. The outcomes for each scenario were assessed on 32 farms, using a 5,000-day time horizon at 1-day time intervals and on an animal- by-animal basis. The 3TAI/24+NM scenario resulted in a greater number of births (293 births) and weaned calves (287 calves), while the ONM scenario had the lowest number of births (207 births) and calves (203 calves). The heaviest males and females at weaning belonged to 3TAI/24, with 190.58 ± 0.77 kg for males and 173.67 ± 0.86 kg for females. The ONM scenario had the lightest males (166.59 ± 0.93 kg) and females (151.65 ± 49 0.74 kg). The greatest and lowest pregnancy rates were found, respectively, in 3TAI/24+NM (0.90 ± 0.00) and ONM (0.61 ± 0.01). The 3TAI/24+NM scenario (US$ 96,479.19 ± 709.81) resulted in higher incomes, while ONM (US$ 79,753.37 ± 741.87) had the lowest incomes from this study. The 3TAI/24+NM (US$ 101.720.6 ± 79.21) and ONM (US$ 90.898.58 ± 59.17) scenario presented the highest and lowest total operating costs (TOC), respectively. However, when TOC was evaluated per kg of weaned calf, the highest and lowest costs were for ONM (US $ 2.8 ± 0.03 / kg) and 2TAI/24+NM (US $ 2.17 ± 0, 04 / kg) respectively. The 2TAI/24+NM scenario (US $ -4.551.28 ± 630.72) presented the best net margin, while the lowest result was for 3TAI/40 (US$ -12.590.04 ± 746.27). The proposed agent-based simulation model has all the advantages of a physical experiment, but it neither requires incurring significant expenses nor altering the real system. Our model provided sufficient evidence to demonstrate that reproductive strategies using TAI have better technical and economic performance than those under NM. The combination of TAI and early pregnancy diagnosis resulted in better technical and economic performance compared to other TAI and NM programs.