Effect of maturity at harvest on yield, chemical composition, and in situ degradability for annual cereals used for swath grazing

Abstract

The objective of this study was to determine how harvest maturity of whole-crop cereals commonly used in swath grazing systems in western Canada affects yield, chemical composition, and in situ digestibility. We hypothesized that the increase in yield with advancing maturity would not offset the decline in digestibility and, thus, the yield of effectively degradable DM (EDDM) would decline with advanced stages of maturity. Four replicate plots of barley (Hordeum vulgare L.; cv. CDC Cowboy), millet (Panicum milliaceum; cv. Red Proso), oat (Avena sativa L., spp.; CDC Weaver), and wheat (Triticum aestivum L.; cv. 07FOR21) were grown, with a subsection in each replicate harvested at 4 different maturities: head elongation, late milk, hard dough, and fully mature. At each stage of maturity, the wet and DM yields, and chemical composition (DM, OM, NDF, crude fat, and nonfiber carbohydrates; NFC) were determined. Whole-crop samples were ground (2-mm screen) and weighed into nylon bags (pore size of 53 ± 10 µm), and duplicate incubation runs were conducted by crop type. For each incubation run, nylon bags were randomly allocated (randomized by field replication, stage of maturity, and incubation time) to 1 of 7 heifers (32 bags/heifer during each run). Degradation rates were determined using a first-order kinetic model and data were analyzed with stage of maturity as a fixed effect and plot as a random effect. The DM, OM, and NFC yields increased linearly for barley and oat (P < 0.001), and increased quadratically for millet and wheat (P ≤ 0.025). Neutral detergent fiber yield increased linearly for barley (P = 0.005) and quadratically for millet, oat, and wheat (P = 0.044). There were no changes in CP yield observed for barley, millet, or oat with advancing maturity, but there was a linear increase observed for wheat (P = 0.002). The NFC concentration increased linearly for barley, millet, and oat (P < 0.001), and quadratically for wheat (P < 0.001), whereas the EDDM concentration decreased quadratically for millet, oat, and wheat (P = 0.003). The degradation rate of NDF decreased linearly with advancing maturity (P ≤ 0.014) for millet, oat, and wheat, but was not affected for barley (P = 0.13). The yield EDDM increased linearly for barley and oat (P < 0.001), and increased quadratically for millet and wheat (P ≤ 0.025). These findings suggest that harvesting whole-crop annual cereals at the hard dough and mature stages may maximize the yield of EDDM.

Nutrient Changes and in Vitro Digestibility in Generative Stage of M10-BMR Sorghum Mutant Lines

“…The same trends were also found by Koten et al (2014) that sorghum harvested at the stage of initiation of grain development had higher ash content compared with those harvested at further maturity (soft dough phase). This result was due to the increased starch content of grains during further generative stage (Marsalis et al, 2009) and the increased organic content such as starch in grain and sugar in the stem as an accumulation result of photosynthesis so that the inorganic matter (ash) was measured lower (Rosser, 2013).…”

“…Qu et al (2014) stated that the decrease in plant fiber content at soft dough phase would increase in vitro DMD. However, Rosser et al (2013) stated that further maturity of forage crops did not reduce in vitro OMD.…”

Assessment of Chemical Composition of Grain Crops Depending on Vegetative Stage for Feeding

“…In its turn, culms and leaves of quackgrass had higher content of NFS than wheatgrass (by 1.4, 3.2%) and smooth brome by 3.7 and 3.8%, respectively. Vegetation phase has a great influence on the chemical composition of crops (Rosser et al, 2013).…”

Evaluation of a phase-feeding strategy utilizing high-lipid high-fibre byproduct pellets in diets for feedlot steers

“…Samples were then composited by period and sent to Cumberland Valley Analytical Services (CVAS, Hagerstown, MD, USA) for chemical analysis as described by Rosser et al (2013) except ether extract that was determined with acid hydrolysis (AOAC 2005; Methods 922.06 and 954.02) to ensure adequate recovery with processed feeds containing a substantial lipid content. Net energy values of feed were calculated by the commercial lab using equations described in the NRC (2001) and also calculated based on animal performance as described by Zinn and Shen (1998) and Zinn et al (2002).…”