Produção de forragem e desempenho animal em pastos em monocultivo ou consorciados com leguminosas

Abstract

Nitrogen (N) is the main nutrient that enables increased productivity in pastures. The most commonly used method to provide N in pasture systems is through fertilization. Another approach is the use of mixed pastures with legumes, which allows for lower production costs. It is hypothesized that the intercropped combination of forage peanuts (Arachis pintoi Krap. & Greg. cv. Mandobi) and/or pigeon pea (Cajanus cajan (L.) Millsp) with marandu grass (Urochloabrizantha (Hochst ex A. Rich) Stapf cv. Marandu) in pasture systems, can replace nitrogen fertilization. The objective was to define mixtures in pastures that are equivalent to pastures fertilized with 150 kg ha-1 year-1 of nitrogen. The experiment was conducted in the DZO/UFLA experimental area, between February 2022 and February 2023. A pre-established pasture with a total of 15 experimental units was used. Five types of pastures were studied: 1) Marandu grass monoculture (Control), 2) Mixed Marandu grass pasture with forage peanuts (B+A), 3) Mixed Marandu grass pasture with pigeonpea (B+G), 4 ) Mixed pasture of Marandu grass with forage peanuts and pigeon pea (B+A+G); 5) Marandu grass fertilized with 150 kg ha-1 year-1 of N (N). Nitrogen application was divided into three periods, in December 2021, January and March 2022. In March 2022, all paddocks were subjected to intensive grazing, followed by the sowing of pigeon peas in their respective plots. In July 2022, two Nelore females were allocated to each experimental unit, with an average age of 180 days and an average weight of 160 kg each. Forage mass, canopy structure and animal production were evaluated. The data were grouped into dry, transition and rainy periods. All data were subjected to the SAS MIXED procedure with 5% probability. The data were grouped into dry, transition and rainy periods. All data were subjected to the SAS MIXED procedure with 5% probability. The highest forage mass was observed in N, followed by B+A and B+A+G. The highest rate of herbaceous forage accumulation was found in spring, in treatments B+A+G and N, under the influence of season and pasture types (p = 0.0398). The nutritional quality of the forage was better in spring (p < 0.05). There was an interaction between types of pastures and seasons in average daily gains, stocking rate and gains per area (p < 0.05). Average daily gain and gain per area were higher in pastures fertilized with N and in those with forage peanut mixtures compared to Control and B+G. B+G and Control pastures were similar in all analyzed variables. Thus, we can state that pigeon peas had little impact on the plant community and grazing animals. Sowing pigeonpea in March limited its development, resulting in a reduction in botanical composition. Sowing at the recommended time can enhance the use of pigeon peas in mixed pastures. Forage peanuts provided performance similar to the use of 150 kg ha-1 of N. It is concluded that forage peanuts are a relevant option for growing mixed pastures.