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The aim of this study was to evaluated twenty-seven scenarios simulated in stocker-finishing beef cattle grazing systems, performed with real data and the aid of integrated Microsoft Excel® spreadsheets. The scenarios, consisted of three intensification levels (management modules): low (native pastures - NP), intermediate (NP + winter pasture – WP) and high (NP + WP + summer pasture – SP); three animal categories: calf, steer and cow; and three commercial arrangements, differing in the purchase and sale prices of animals: high/low (unfavorable), medium/medium (medium) and low/high (favorable). With unfavorable prices only the calf responded positively to the increasing level of system intensification, while steer and cow lost margin when the system was intensified with SP compared to the intermediate level. Between categories, the cow has negative margins at all intensification levels, the steer has the best margin at low and intermediate levels, and the calf at high level. In the context of average prices, the cow continues to decrease its margin due to intensification with SP. However, it obtains positive results in all management modules. In this case, the steer shows increasing gains with system intensification, demonstrating better performance than the calf in all management modules. In favorable price situations, all categories show increasing gains per area as the system intensifies. At this juncture, at an intermediate intensification level, the cow has the best performance per area between categories, while at low and high levels the steer responds with the best margin. When assessing the margin/head/year, in any commercial and animal category, intensification with SP loses competitiveness in relation to the intermediate intensification management module. However, when the margin/area was evaluated, only 3 of 27 scenarios decreased the margin.

Our goal was to define a breeding objective for Brangus beef cattle in Brazil. Bioeconomic models were produced and used to estimate economic values (EVs). The scenarios simulated were typical full-cycle beef production systems that are used in tropical and subtropical regions. The breeding objective contained pregnancy rate (PR), warm carcass weight (WCW), mature cow weight (MCW), number of nematode eggs per gram of faeces (EPG) and tick count (TICK). Two models were used in series to estimate the EV. A deterministic model was used to simulate effects of PR, WCW and MCW on profitability with a constant parasite load. Subsequently, stochastic models were used to estimate economic values for TICK and EPG as consequences of their environmental effects on weight gains, mortality and health costs. The EV of PR, WCW, MCW, EPG and TICK, was US$1.59, US$2.11, -US$0.24, -US$5.35 and -US$20.88, respectively. Results indicate positive emphasis should be placed on PR (12.49%) and WCW (65.07%) with negative emphasis on MCW (13.92%), EPG (2.77%) and TICK (5.75%). In comparison with the indexes usually used, these results suggest a reformulation in the selection indexes of the beef production system in tropical and subtropical regions in order to obtain greater profitability.

This paper aimed to identify and evaluate the effects of sire breed on temperament and productive traits of different cross-breeds between Nellore (NE), Tabapua (TB), and Brahman (BR) bulls mated with Angus cows (AN), as well as the relationship between temperament and productive traits. The productive traits measured in this study include slaughter weight and post weaning weight gain. Temperament was assessed by flight-speed (FS). Carcass data collected in this study include hot carcass weight, hot carcass percentage, cold dressing percentage, carcass length, initial pH, ultimate pH, subcutaneous fat thickness and carcass longissimus muscle area. The sire breed effect was greater for slaughter weight. Hot carcass weight was not affected by the sire breed. The longissimus muscle area was larger for AN x TB and AN x NE crossbreeds than for AN x BR crossbreeds. Subcutaneous fat thickness and cold dressing percentage were not affected by sire breed. The offspring of NE, TB, and BR sires mated with AN cows had similar carcass measurements, except for the longissimus muscle area, which was smaller for offspring sired by the Brahman breed. The temperament trait was not influenced by sire breed.