Short communication: Influence of various proteolytic sources during fermentation of reconstituted corn grain silages

Abstract

The objective of this study was to determine the contribution of corn kernel enzymes, bacteria, fungi, and fermentation end-products (main acids and ethanol) to protein solubilization during fermentation of reconstituted corn grain silage. Flint corn kernels were ground (5-mm sieve), rehydrated to 32% of moisture, and treated with no additives (control), gamma irradiation (32 kGy), gamma irradiation + fermentation end-products (1% of lactic acid, 0.3% of acetic acid, and 0.7% of ethanol, as fed), and natamycin (1% as fed). Treated grains were ensiled in nylon-polyethylene bags and stored for 90 d. Protein solubilization was calculated for each treatment and the contributions of proteolytic sources were determined. Bacterial activity was the main contributor to proteolysis (60%) followed by corn kernel enzymes (30%), whereas fungi and fermentation end-products had only minor contributions (∼5% each).

Effects of length of ensiling and maturity group on chemical composition and in vitro ruminal degradability of whole‐crop maize

“…() observed a similar increase in NH 3 ‐N that even continued after d120 up to 240 days of storage. In reconstituted maize grain silage, proteolysis was mainly caused by bacterial activity (60%) followed by maize kernel enzymes (30%) (Junges et al., ). Protein is not a major constituent in maize silages but, in high‐maize rations, a considerable part of the dietary CP originates from maize such that type and amount of the ruminal degradation affect both supply of N compounds for microbial synthesis in the rumen as well as amount and composition of the ruminally undegraded dietary CP (Südekum, ).…”

“…proteins in the starch-protein matrix by proteolytic activity (Hoffman et al, 2011). Recent research by Junges et al (2017) showed that protein solubilization in reconstituted maize grain silage was mainly caused by bacterial activity (60%) followed by maize kernel enzymes (30%), whereas fungi and fermentation end-products had only minor contributions (~5% each). The composition of the starch-protein matrix is, besides other factors, influenced by the genotype of the plant (Bal, Shaver, Al-Jobeile, Coors, & Lauer, 2000;Hoffman et al, 2011) and the maturity at harvest (Correa, Shaver, Pereira, Lauer, & Kohn, 2002).…”

Fermentation profile and identification of lactic acid bacteria and yeasts of rehydrated corn kernel silage

“…; Junges et al . ; Morais et al . ), mainly owing to high endosperm vitreousness (high concentration of the hydrophobic starch–protein matrix surrounding starch granules) and consequently the low digestibility of corn hybrids cultivated currently in Brazil (Correa et al .…”

“…The reduction in total-starch digestibility may be explained by the increase in kernel vitreousness (Correa et al 2002;Hoffman et al 2011). Considering the advantages, the process of using corn kernel rehydration for silage has gained interest with Brazilian researchers (Rezende et al 2014;Junges et al 2015;Morais et al 2015), mainly owing to high endosperm vitreousness (high concentration of the hydrophobic starch-protein matrix surrounding starch granules) and consequently the low digestibility of corn hybrids cultivated currently in Brazil (Correa et al 2002). Characterizing the microbial communities present in silage may help to understand silage fermentation, intervene in the fermentation process and improve the quality of silages.…”

Effect of microbial inoculation and particle size on fermentation profile, aerobic stability, and ruminal in situ starch degradation of high-moisture corn ensiled for a short period

“…Organic acid production is often reduced in HMC because bacterial growth is inhibited due to limited water availability (Muck, 1988). Reduced organic acid production in HMC has been associated with reduced starch digestibility (Ferraretto et al, 2014), presumably because bacterial proteolysis in the silo is the primary mechanism associated with the breakdown of the protein matrix (Junges et al, 2017). Furthermore, Simpson (2001) reported that a low pH favors the activity of endosperm proteases in cereal grains, which may contribute to improvements in starch digestibility; endosperm proteases represent 30% of proteolysis occurring in the kernel during silo fermentation (Junges et al, 2017).…”