Present study is focused on the quality parameters of maize hybrids used as animal feed and on the evaluation of the effect of sowing dates and weather factors. Our experiments were performed at the Experiment Site of the University of Debrecen, (47°33’ N, 21°26’ E, 111 m), on calcareous chernozem soil between 2011–2013. The experiment took place with the involvement of three sowing dates (VD) and three hybrids (FAO 290, FAO 350 and FAO 420) with natural precipitation supply. The three-year result showed that the cumulative Growing Degree Day (GDD) value was high during the growing season of VD1 and VD2 sowings, but the low temperature recorded at the early stages of plant development reduces the protein and oil content of the maize grain. Thus, with the postponement of sowing (VD3), where daily temperatures are higher, but the cumulative GDD value of the growing season is lower, the protein and oil content of the maize grain increased by 12.5, 12.8% (P<0.05, P <0.05). Overall, the year with the highest GDD value and only 277 mm of precipitation during the growing season (2012) had the highest protein content (10.5 g per 100 g dry matter, P<0.05) in the average of hybrids and VD, while oil content was the lowest (4.6 g per 100 g dry matter, P<0.05). Protein content of the hybrids was proven to be the highest (P<0.05) in the VD3 sowing (with the exception of FAO 350 (VD2), and the VD3 sowing also resulted in the highest (P<0.05) oil content in the case of all three hybrids.

Keywords: genotype, sowing date, Growing Degree Day (GDD), protein content, oil content