Effect of feeding on the composition of longissmus muscle of Hungarian Grey and Holstein Friesian bulls - III. Amino acid composition and mineral content

Abstract

In this experiment the effect of the extensive diet (grass/grass silage and concentrate linseed supplemented) versus intensive diet (maize silage and concentrate) on the amino acid composition and mineral content of Hungarian Grey and Hungarian Holstein Friesian young bulls was analysed. In addition the relationships between fatty acid profile and amino acid composition as well as mineral content of longissimus muscle were investigated. The extensive diet caused some changes in the proportion of some amino acids including isoleucine, leucine, phenylalanine, threonine, valine, cysteine, glycine, proline, serine and ammonia. The breed influenced only the histidine concentration of longissimus muscle. In extensive groups arginine to glycine and arginine to leucine ratios were higher compared to intensive fed bulls. The mineral composition of longissimus muscle was mainly influenced by diet and there was a breed x diet interaction, whereas breed differences were detected for calcium (Ca) and sodium (Na). The phosphorus (P) and the iron (Fe) content in longissimus muscle of extensively fed animals were significantly higher, whereas Na and copper (Cu) content were lower. The beef of Hungarian Grey bulls contained less Ca and Na compared to Holstein counterparts. Cysteine and leucine concentration were positively correlated to intramuscular fat content and negatively with n-3 and n-6 fatty acids (FA). Among minerals the P and Fe content correlated negatively to intramuscular fat content. The closest correlations were determined between P and linolenic acid (C18:3n-3) as well as n-3 fatty acids (r=0.81). The lower n-6 and n-3 fatty acid ratio in extensive groups occured simultaneously with higher proline, valine, phenylalanine, P, and with lower glycine, cystine, leucine and sodium proportion in longissimus muscle.