Amino acid contents and intestinal digestibility of lucerne in ruminants as influenced by growth stage
2008
Homolka, P.,Vyzkumny Ustav Zivocisne Vyroby, Prague (Czech Republic) | Koukolova, V.,Vyzkumny Ustav Zivocisne Vyroby, Prague (Czech Republic) | Nemec, Z.,Ceska Zemedelska Univ., Prague (Czech Republic). Katedra Mikrobiologie, Vyzivy a Dietetiky | Mudrik, Z.,Ceska Zemedelska Univ., Prague (Czech Republic). Katedra Mikrobiologie, Vyzivy a Dietetiky | Hucko, B.,Ceska Zemedelska Univ., Prague (Czech Republic). Katedra Mikrobiologie, Vyzivy a Dietetiky | Sales, J.,Vyzkumny Ustav Zivocisne Vyroby, Prague (Czech Republic)
Lucerne (var. Palava), harvested at four successive dates over a 30-day period, was evaluated for chemical composition (dry matter, organic matter, crude protein, ether extract, crude fibre, nitrogen-free extract, neutral detergent fibre, acid detergent fibre, acid detergent lignin), amino acid concentrations and intestinal digestibility in dairy cows. Dry matter (r = 0.78), organic matter (r = 0.95), crude fibre (r = 0.91), neutral detergent fibre (r = 0.94), acid detergent fibre (r = 0.79) and acid detergent lignin (r = 0.48) presented positive linear correlation coefficients with growth stage, whereas crude protein (r = -0.96), ether extract (r = -0.86) and nitrogen-free extract (r = -0.70) showed negative relationships. Total essential amino acid content decreased (r = -0.94) from 84.1 to 55.3 g/kg of dry matter with maturity. With the exception of tyrosine (r = -0.68), r values between growth stage and individual non-essential amino acids were all higher than -0.90. Total amino acid (r = -0.98) and nitrogen (r = -0.99) contents presented comparable tendencies with successive sampling times. No definite trends were detected for the amino acid composition of rumen incubated (16 hours) lucerne samples. The intestinal digestibility of total essential (r = -0.78), total non-essential (r = -0.58) and total (r = -0.69) amino acids as well as nitrogen (r = -0.99) decreased with growth. However, due to a small sample size (n = 4), most linear relationships between constituents and growth stage were insignificant.
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