Serum amino acid and myofibrillar protein profiles in Boer goat bucks following undernutrition

The aim of the work was to determine serum free amino acid and myofibrillar protein profiles in Boer goats following undernutrition in order to study the physiological consequences of undernutrition in this goat breed. Fifteen Boer goat bucks were allocated to two experimental groups: CG (control group), fed ad libitum Themeda trianda hay, supplemented with maize, molasses and urea; and RG (underfed group) fed only the same hay (80 and 86% of the daily energy and protein requirements, respectively). Blood was collected weekly for determination of the serum free amino acid profiles. Animals were slaughtered at day 28 and the semi-membranosus muscle was sampled for myofibrillar protein profile determinations. At the last collection date CG animals had higher concentrations of Ala, Tyr and Cit; RG group showed higher concentration of Val, Ile, Leu, Thr, Met, Lys, Tau, Orn, Hyp and 3-metyl histidyne (Me3His), while Gly, Ser, Asp, Glu, Arg, His and Pro were similar in both groups. The RG group showed myofibrillar protein degradation of protein C and alpha-actinin. From the results it can be concluded that serum amino acid and myofibrillar protein profiles in the goat are strongly affected by undernutrition. Amino acid results suggest that the degradation of small carbon chain amino acid has a higher efficiency than degradation of long carbon chain amino acid. Myofibrillar protein profiles suggest a disruption of muscle structure at the level of the second third of each half of the A band (protein C) and the matrix of the Z line (alpha-actinin). (C) 2004 Elsevier B.V. All rights reserved.