Journal of Agricultural Science; Vol. 7, No. 1; 2015 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 88 Nitrogen Fertilization in Coastcross Pastures Associated with Forage Peanut on Nutritional Composition of Forage and Animal Performance Ulysses Cecato 1 , José Augusto Nogueira Gomes 1 , Fabiola Cristine de Almeida Rego 2 , Elir de Oliveira 3 , Wagner Paris 4 , Leandro Barbero 5 , Sandra Galbeiro 6 , Alexandre Lenzi 7 & Elias Nunes Martins 1 1 Department of Animal Science, State University of Maringá (UEM), Maringá, PR, Brazil 2 Department of Animal Science, University of North Paraná (UNOPAR), Arapongas, PR, Brazil 3 Agronomic Institute of Paraná (IAPAR), Campo Mourão, PR, Brazil 4 Federal Technological University of Paraná (UFTPR), Dois Vizinhos, PR, Brazil 5 Federal University of Uberlândia, Uberlândia, MG, Brazil 6 State University of Londrina (UEL), Londrina, PR, Brazil 7 Federal University of Santa Catarina (UFSC), Florianópolis, SC, Brazil Correspondence: Fabiola Cristine de Almeida Rego, Department of Animal Science, University of North Paraná (UNOPAR), Arapongas, PR 86708-000, Brazil. Tel: 55-43-3172-7570. E-mail: fabiolaregogrecco@gmail.com Received: October 10, 2014 Accepted: November 7, 2014 Online Published: December 15, 2014 doi:10.5539/jas.v7n1p88 URL: http://dx.doi.org/10.5539/jas.v7n1p88 Abstract The experiment was carried out at IAPAR, in Paranavaí-PR, from July 2002 to June 2007. A completely randomized design was used, with two replications and such treatments: Coastcross (Cynodon dactylon [L] Pers Cv Coastcross) + forage Peanut (Arachis pintoi Krapovickas and Gregori. Cv. Amarillo) + 200 kg ha -1 of N; Coastcross + forage Peanut + 100 kg ha -1 of N; Coastcross + 200 kg ha -1 of N and Coastcross + forage Peanut. Cross heifers were used (Red angus × Nelore × Limousin), three of them as testers plus the regulator animals, with medium initial weight of 170 kg, and management in continuous stocking and variable stocking rate. The pasture was maintained to a medium height of, approximately, 17 cm. For the nutritional value evaluations (crude protein,CP, neutral detergent fibber, NDF, and in vitro dry matter digestibility, IVDMD) forage samples were collected, each 28 days, and separated in leaf blade, sheath+stem, dead material and plants of forage Peanut. The animal production was evaluated through the average daily gain (ADG, kg ha -1 day -1 ), weighted in fast each 28 days, stocking rate (AU, animal unit ha -1 ; being that the animal unit corresponds to 450 kg of live weight) and body weight gain (BWG, kg ha -1 ). Pastures of grasses and legumes with no N fertilization have a lower nutritional composition than fertilized pastures. Forage nutritional composition and animal performance vary according to the conditions each year, thereby affecting stocking rate and live weight gain. Keywords: animal performance, forage mass production, grazing cattle, stocking rate 1. Introduction Animal performance on pasture systems depends on forage intake and quality, as well as on management, fertilization, and intrinsic factors of the forage. Fertilization is important in the pasture production process because having an adequate amount of nutrients, mainly nitrogen, results in greater forage productivity and therefore greater animal performance (Fagundes et al., 2006). However, large amounts of N fertilization in the pasture can also lead to increased production costs and may contribute to environmental contamination (Primavesi et al., 2006). Thus, some researchers have studied the benefits of grasses and legumes on pastures (Rego et al., 2006) and animal productivity (Paris et al., 2009). Moreover, this type of pasture management represents an alternative, low cost method of reducing degradation (Aroeira et al., 2005) due to the N supply in the production system. Studies regarding forage nutritional composition are essential in grazing animal production systems because they can provide important information about limiting factors related to the intake of nutrients and therefore, provide information about factors affecting animal production (Brâncio et al., 2002). Thus, it is possible to improve productivity greater than 1.000 kg live weight ha -1 year -1 with management techniques and an adequate forage