Effects of hybrid and maturity on the conservation and nutritive value of snaplage

Abstract

The aim of this study was to assess different hybrids of corn harvested at three maturities to make snaplage. Over two crop years, five hybrids were grown at 70,000 plants/ha on plots (6 × 5 m) in three blocks. Hybrids were harvested at the target maturity levels of 600 g/kg of dry matter (DM; M1), 650 g/kg of DM (M2), and 700 g/kg of DM (M3). Fresh ears were separated into kernels, husk, and cob. Whole ears were processed and ensiled (snaplage) in 5-L jars for 90 d. Measurements included DM yield, nutrient analysis, in vitro neutral detergent fiber digestibility (NDFD30h,), and in situ starch degradability (isSD) for ear components and snaplage. The experimental design was randomized complete blocks using a mixed repeated measures model. Data were analyzed using the MIXED procedure of SAS, followed by Student’s t-test at P ≤ 0.05. The DM concentrations at harvest were 591, 642, and 683 g/kg for M1, M2 and M3, respectively. There was an interaction between hybrid and maturity (P = 0.03) for kernel proportion. The aNDF concentrations of cob and husk increased and the NDFD30h of both parameters decreased from M1 to M3. The greatest lactic acid and NH3-N concentrations (38.2 g/kg of N) were found at M1. The M3 had the longest aerobic stability. The starch concentrations and isSD of snaplage were affected by hybrid and maturity level (P < 0.05). As maturity increased, the isSD decreased (783, 731, and 703 g/kg of starch for M1, M2 and M3, respectively). Overall, corn hybrids differed in ear components proportions and those with lower vitreous endosperm had greater starch degradability. The NDFD30h of cob and husk and the starch degradability of kernels and snaplage declined from M1 to M3. Snaplage should be produced with 600–700 g/kg of DM. Harvesting at DM concentrations lower than 600 g/kg compromised starch concentration; but DM concentrations greater than 700 g/kg may impair starch degradability due to restriction in fermentation.