Influence of nitrogen fertilization on the energy value of maize grain in non-ruminants

R. Bazitov1*, M. Mihaylova1, G. Ganchev2

1Agricultural Institute, 6000 Stara Zagora, Bulgaria
2Department of Fundamental Sciences in Animal husbandry, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received June 2022; accepted for publication 18 May 2023)

Abstract. Maize is the most widely spread energy source used in rations for farm animals and poultry, especially in countries in America, Southern Europe and Asia, where maize grain is the main cereal used for feed. The quality of maize grain is formed under the influence of several interrelated factors. The aim of the study is to determine the effect of different rates of nitrogen fertilization on the chemical composition and energy value of maize grain grown under irrigation conditions in non-ruminants. The study was conducted in the experimental field of the Agricultural Institute – Stara Zagora under irrigation conditions on cinnamon-meadow soil with maize for grain, medium late hybrid LG 35.36 with density of crops – 70000 plants per hectare. The study includes the following four treatments of fertilization: 1 experimental variant N0P80K60 – non-fertilizer control, 2 experimental variant N100P80K60 – fertilization with 100 kg N.ha-1, 3 experimental variant N150P80K60 – fertilization with 150 kg N.ha-1 and 4 experimental variant N200P80K60 – fertilization with 200 kg N.ha-1. Nitrogen fertilizer was applied during the vegetation of the crop in phase 3-5 leaf, and phosphorus and potassium fertilizers in rates 80 kg P2O5.ha-1 and 60 kg K2O.ha-1 in the main tillage. During the vegetation of the maize, pre-irrigation humidity of 80-85% of field capacity (FC) was maintained by 3 waterings. As the fertilization rate increases, the crude protein content in the maize grain also grows up. During the treatment with the highest fertilizer rate of 200 kg N.ha-1, 9.5% per 1 kg of dry matter (DM) was obtained, followed by the treatment with 150 kg N.ha-1 – with a value of 9.1% per 1 kg of dry matter. The content of crude fiber in the grain of maize with increasing fertilization rate decreases, being the smallest in the treatment with rate 100 kg N.ha-1 – 0.8% per 1 kg of dry matter. The fertilization rate does not have a significant effect on the content of digestible and metabolite energy in corn grain grown under irrigated conditions in pigs and poultry.