Objective:

To characterize the growth dynamics of fattening males under rational Voisin grazing conditions on soils with undulated to rough topography, in the humid tropics of Los Santos, Panama.

Materials and Methods:

The trial was conducted in a production area of 8,40 ha, divided into 24 paddocks of 0,35 ha as average. The pastures were managed according to the principles and concepts of rational Voisin grazing. Fifty-three steers were used, with Zebu basis and its F1 and F2 crossings (Zebu x Holstein), divided into two fattening groups. The first fattening period (27 animals) lasted 150 days, and the second (26 animals), 79 days. The initial weights were 369 and 401 kg, for the first and second group, respectively. The animals were weighed every 30 days to determine live weight gain per period and individual daily gain. The data were processed by variance analysis and Duncan’s test was used for p < 0,05.

Results:

The grazing pressure was high (4,63 kg DM/100 kg LW/day), with an average pasture availability of 23,2 kg DM/a/day. The animals of the first fattening cycle averaged 0,653 kg/day, with a beef production per hectare of 336,63 kg. In the second cycle, they gained 0,670 kg per day; while beef production was 145,55 kg/ha. The two continuous fattening periods allowed the farmer to sell more than 24 t of live beef in one year.

Conclusions:

It is concluded that the fattening of Zebu bulls and its F1 and F2 crossings in a Voisin rational grazing system is feasible, because average gains close to 0,700 kg/animal/day are obtained, without weight loss at times of higher food shortage.

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