Amino acid levels in muscle tissue of eight meat cattle breeds

Abstract

Ten clinically healthy bulls equal in weight were chosen from eight meat cattle breeds maintained in the same geographical conditions using the extensive grazing method. After slaughtering, muscle tissue samples were taken from the musculus longissimus and pars thoracis, and dry matter, nitrogenous substances, fat, and the levels of essential (EAAs) and non-essential (NEAAs) amino acids were determined. Significant differences were found between the monitored genotypes in the contents of dry matter, nitrogenous substances, fat, EAAs, and NEAAs (P ≤ 0.05). The highest concentrations of nitrogenous substances in muscle tissue were detected in the Limousine breed and the lowest in the Aberdeen Angus breed; the highest fat content was found in Aberdeen Angus and the lowest in Galloway. Out of the total sum of EAAs, the highest percentage in the dry matter of muscle tissue in all genotypes was found for Lys (8.8-10.4%), the lowest percentage was found for Met (2.4-2.9%). The value of Thr was approximately 4.6, Val 5.1, Ile 4.8, Leu 8.2, Phe 4.1, His 4.2, and Arg 8.0%. Significant differences (P ≤ 0.05) between the monitored breeds were found in all EAAs, except for Val and Leu. Regarding NEAAs, out of the total protein, the highest percentage was found for Glu (13.9-15.1%). Conversely, the lowest values were detected for Ser (3.8-4.1%) and Tyr (3.8-4.4%). The values of other NEAAs were approximately 9.3 for Asp, 4.0 for Ser, 5.3 for Pro, 5.5 for Gly, and 6.1% for Ala. Significant differences (P ≤ 0.05) were found between the monitored genotypes in all NEAAs except for Pro and Ala. In the dry matter of muscle tissue, out of the total protein, the sum of EAAs ranged from 50.6 (Meat Simmental) to 52.0% (Limousine), and NEAAs ranged from 48.0 (Limousine) to 49.4% (Meat Simmental). Apart from its effect on the biological value of meat, representation of individual amino acids is important to enhance its taste or smell.