A method for identifying a maize plant or plant part from maize having improved digestibility comprising a) screening for the presence of a QTL allele, such as a QTL allele associated with improved digestibility, said QTL allele comprising a nucleotide sequence of a gene encoding a cytochrome P450 flavonoid 3',5'-hydroxylase (F35H), having a mutation leading to reduced or absent expression of the mRNA of the gene and/or the F35H protein (such as a knock-down or knock-out mutation), or a mutation leading to a non-functional F35H protein (e.g., truncated F35H protein) or an F35H protein having reduced enzymatic activity upon translation, or b) screening for reduced or absent expression of the mRNA of a gene encoding a cytochrome P450 flavonoid 3',5'-hydroxylase (F35H) and/or the F35H protein or for a non-functional F35H protein (e.g., truncated F35H protein) or an F35H protein having reduced enzymatic activity, or c) screening for the presence of a mutation leading to reduced or absent expression of the mRNA of a gene encoding a cytochrome P450 flavonoid 3',5'-hydroxylase (F35H) and/or the F35H protein, or a mutation leading to a non-functional F35H protein or an F35H protein having reduced enzymatic activity upon translation; wherein improved digestibility relates to increased digestibility of the maize plant or plant part from maize having the characteristic of a), b) or c) compared to a maize plant or plant part from maize not having such characteristic; and wherein the unmutated F35H is selected from the group consisting of: (i) a nucleotide sequence comprising the sequence of SEQ ID NO: 1; (ii) a nucleotide sequence having the cDNA of SEQ ID NO: 2; (iii) a nucleotide sequence encoding for an amino acid sequence having the amino acid sequence of SEQ ID NO: 3; (iv) a nucleotide sequence having at least 80% identity to the sequence of SEQ ID NO: 1, or 2; (v) a nucleotide sequence encoding for a polypeptide having at least 80% identity to the sequence of SEQ ID NO: 3; (vi) a nucleotide sequence hybridizing with the reverse complement of a nucleotide sequence as defined in (i), (ii) or (iii) under stringent hybridization conditions. a) screening for the presence of a QTL allele, such as a QTL allele associated with improved digestibility, said QTL allele comprising a nucleotide sequence of a gene encoding a cytochrome P450 flavonoid 3',5'-hydroxylase (F35H), having a mutation leading to reduced or absent expression of the mRNA of the gene and/or the F35H protein (such as a knock-down or knock-out mutation), or a mutation leading to a non-functional F35H protein (e.g., truncated F35H protein) or an F35H protein having reduced enzymatic activity upon translation, or b) screening for reduced or absent expression of the mRNA of a gene encoding a cytochrome P450 flavonoid 3',5'-hydroxylase (F35H) and/or the F35H protein or for a non-functional F35H protein (e.g., truncated F35H protein) or an F35H protein having reduced enzymatic activity, or c) screening for the presence of a mutation leading to reduced or absent expression of the mRNA of a gene encoding a cytochrome P450 flavonoid 3',5'-hydroxylase (F35H) and/or the F35H protein, or a mutation leading to a non-functional F35H protein or an F35H protein having reduced enzymatic activity upon translation; wherein improved digestibility relates to increased digestibility of the maize plant or plant part from maize having the characteristic of a), b) or c) compared to a maize plant or plant part from maize not having such characteristic; and wherein the unmutated F35H is selected from the group consisting of: (i) a nucleotide sequence comprising the sequence of SEQ ID NO: 1; (ii) a nucleotide sequence having the cDNA of SEQ ID NO: 2; (iii) a nucleotide sequence encoding for an amino acid sequence having the amino acid sequence of SEQ ID NO: 3; (iv) a nucleotide sequence having at least 80% identity to the sequence of SEQ ID NO: 1, or 2; (v) a nucleotide sequence encoding for a polypeptide having at least 80% identity to the sequence of SEQ ID NO: 3; (vi) a nucleotide sequence hybridizing with the reverse complement of a nucleotide sequence as defined in (i), (ii) or (iii) under stringent hybridization conditions. (i) a nucleotide sequence comprising the sequence of SEQ ID NO: 1; (ii) a nucleotide sequence having the cDNA of SEQ ID NO: 2; (iii) a nucleotide sequence encoding for an amino acid sequence having the amino acid sequence of SEQ ID NO: 3; (iv) a nucleotide sequence having at least 80% identity to the sequence of SEQ ID NO: 1, or 2; (v) a nucleotide sequence encoding for a polypeptide having at least 80% identity to the sequence of SEQ ID NO: 3; (vi) a nucleotide sequence hybridizing with the reverse complement of a nucleotide sequence as defined in (i), (ii) or (iii) under stringent hybridization conditions.