Effect of nitrogen application rate on yield, forage quality, and animal performance in a tropical pasture

Lutti M Delevatti,Rondineli P Barbero,Abmael S Cardoso,Eliéder P Romanzini,Ana C Ruggieri,Rhaony G Leite,Ricardo A Reis

doi:10.1038/s41598-019-44138-x

Abstract

A three-year-long field experiment was conducted in a continuous grazing system with a variable stocking rate to evaluate effects of increasing nitrogen levels in Marandu grass (Brachiaria brizantha Hochst ex A. Rich Stapf “marandu”) on herbage mass, forage accumulation rate (FAR), forage quality, stocking rate (SR), average daily gain (ADG), gain per hectare (GPH), and gain per kg of applied N. The experimental design was completely randomized with four treatments (control without application of N, and 90, 180, and 270 kg N ha−1 year−1) and three replicates (paddocks per treatment); nitrogen was applied in the form of urea. Herbage mass, crude protein (CP), FAR, SR, GPH, and the nitrogen nutrition index increased with increasing nitrogen level (P < 0.05), whereas the neutral detergent fibre (NDF), acid detergent fibre, and nitrogen usage efficiency decreased with increasing nitrogen level (P < 0.01). Crude protein was higher than 12% and NDF lower than 60% in all treatments. Nitrogen application rate affected ADG (P < 0.05) but did not fit any equation. The highest ADG was 90 kg N ha−1 year−1 (985 g animal−1 day−1). Increasing the nitrogen level is a promising way to improve Marandu grass production, nutritive value, and animal production.

Highlights

Protein is a vital nutrient for human nutrition and animal meat is the main source of protein for the human population[1]
Most of the animal production in tropical areas is based on forage and inadequate grazing management can be responsible for insufficient yield in animal production systems[5]
Our results were similar to those measured in a site 1200 km from our study (Cerrado region), and documented a value of 6098 kg Dry matter (DM) ha−1 11

Summary

Introduction

Protein is a vital nutrient for human nutrition and animal meat is the main source of protein for the human population[1]. Most of the animal production in tropical areas is based on forage and inadequate grazing management can be responsible for insufficient yield in animal production systems[5]. Most studies on grazing strategies aim to improve forage production and animal performance and are based on pasture height. These studies typically investigate the effects of fertilizer use alone. Associating pasture management at 95% IL with nitrogen fertilizers could result in high forage production, nutritive value, and animal performance[9]. We aimed to quantify the effect of application of varying nitrogen doses on the forage yield, chemical composition, nitrogen usage efficiency (NUE), and animal performance in a tropical Marandu grass pasture. Effect linear linear quadratic ns linear linear ns linear linear quadratic ns ns ns (3) enhance the ratio of absorbed and critical levels of nitrogen required by plants (nitrogen nutrition index – NNI), and (4) decrease the NUE

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Conclusion