Influence of Maize Endosperm Mutants on Ground Kernel In Vitro Dry Matter Disappearance
1974
Garwood, D. L. | Shenk, J. S. | Barnes, R. F.
Ground kernels of the W64A maize (Zea mays L.) in. bred and 5 single and 10 double endosperm mutants of maize converted to W64A were evaluated using a twostage in vitro rumen fermentation system with and without urea added to the digestion buffer. In vitro dry matter disappearance (IVDMD) values were not correlated with protein content. Urea addition raised IVDMD values to the same level for most genotypes. Four genotypes were investigated using only first-stage digestion for 3, 6, 12, 24, and 48 hours. Maximum differences were observed after 12 and 24 hours of digestion. At these times, opaque-2 was most degraded followed by waxy, normal, and amylose-extender. The superior rate of opaque-2 digestion compared to waxy could not be explained by differences in particle sizes nor by known rates of isolated starch granule digestion. We suggest that incubation times used for forage IVDMD studies utilizing the basic procedure of Tilley and Terry be shortened when comparing ground grain samples.
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