Simulation and economic analysis of beef cattle natural service and induced twinning via embryo transfer following AI breeding and two calf management systems

Abstract Text: The objective of this project was to compare operation profitability, through simulation, of alternate breeding and calf management strategies. Mating systems considered included A) 60 day natural bull service and B) a fixed-timed A.I. program with implanted embryos 7 days following A.I. to create twins. A 42 day natural service followed embryo transfer. The effect of a pre-weaning calf nutrient supplementation system that excludes cows (creep feeding) was also of interest. The combination of mating system and calf nutritional management system yield different management systems for comparison, including: (1) Induced twin calving system with calf creep feeding (2) Induced twin calving system without calf creep feeding (3) Natural service (single calving) system with calf creep feeding (4) Natural service (single calving) system without calf creep feeding. Microsoft Excel was used to develop a spreadsheet that processed input cost and revenue projections and predicted profitability of each management system. Equations to predict breeding and calf performance allowed entry of different parameters for fertility rates, input costs, and price expectations which vary across different cattle operations, management, and economic environments. Assumptions incorporated into the simulation included: 1) all natural service cows have single births; 2) No change in stocking rate/pasture usage; 3) simulation in second year of twin production; 4) no heifers involved; 5) if a calf dies, it died the day it was born; 6) no difference in genetic potential between A.I./E.T. calves and natural service calves. Sensitivity analysis of the simulation model suggests that variation in labor, creep feeding, and reproductive costs between twin and single calving had the greatest impact on profitability. Creep feeding had a substantially greater positive effect on the performance of twin calves as compared to single born calves; thus creating a much greater impact on overall profitability of that management system. Through simulation utilizing common production input costs, creep feed at $220/ton, it was found that management system (1) induced twinning system with creep feed was the most profitable, if reproductive costs could be held under $170 per head.

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Keywords: management systems, twinning, beef cattle