Potential of Using Maize Cobs in Pig Diets - A Review

Coproduction of alkaline protease and xylanase from genetically modified Indonesian local Bacillus halodurans CM1 using corncob as an inducing substrate

The production of corn generates a substantial amount of agro-industrial waste, with corncob accounting for a significant portion of this waste. In this study, we focused on utilizing corncob as a carbon source and inducer to simultaneously produce two valuable industrial enzymes, protease, and xylanase, using a recombinant strain of B. halodurans CM1. Interestingly, xylan-rich corncob not only enhanced the xylanase activity but also induced protease activity of the modified B. halodurans CM1 strain. The effect of corncob concentration on the coproduction of protease and xylanase was investigated. Corncob with 6 % concentration induced protease activity of 1020.7 U/mL and xylanase activity of 502.8 U/mL in a 7 L bioreactor under the condition of 1 vvm aeration, 250 rpm agitation, 37 °C temperature, initial pH 9.0, and 40 h incubation period. The protease produced was an alkalothermophilic enzyme whose highest activity was at pH 12 and 50 °C, and it belonged to a serine protease family. This alkalothermophilic protease's activity to some degree was reduced by Co2+, Mg2+, Fe2+, Zn2+, and K+, but enhanced by Ca2+ and Ni2+ (at 5 mM). The protease was stable even under the presence of a 15 % concentration of acetone, DMSO, ethanol, and isopropyl alcohol. The protease activity at 30 °C was not considerably changed by the presence of detergent, indicating excellent potential as a washing detergent additive. According to these findings, corncob has the potential to be a substrate for the coproduction of protease and xylanase, which have a wide range of industrial uses.

Characterization and nutritional valorization of agricultural waste corncobs from Italian maize landraces through the growth of medicinal mushrooms

The research investigates the potential use of maize cobs (or corncobs) from five genotypes, including the B73 inbred line and four locally cultivated landraces from Northern Italy, as substrate for implementing Solid State fermentation processes with four Medicinal Mushrooms (MMs). The corncobs were characterized based on their proximate composition, lignin, phenolics content (both free and bound), and total antioxidant capacity. Among the MMs tested, Pleurotus ostreatus and Ganoderma annularis demonstrated the most robust performance. Their growth was parametrized using Image Analysis technique, and chemical composition of culture samples was characterized compared to that of corncobs alone. In all culture samples, the growth of MMs led to a significant reduction (averaging 40%) in the total phenolics contents compared to that measured in corncobs alone. However, the high content of free phenolics in the cobs negatively impacted the growth of P. ostreatus. The final MM-corncob matrix exhibited reduced levels of free sugars and starch (≤ 2.2% DW, as a sum) and increased levels of proteins (up to 5.9% DW) and soluble dietary fiber (up to 5.0% DW), with a notable trend toward higher levels of β-glucan compared to corncobs alone. This research paves the way for the use of this matrix as an active ingredient to enhance the nutritional value of food preparations.

Precision Feeding in Ecological Pig-Raising Systems with Maize Silage

Simple Summary

Generally, ecological farming is regarded as an environmentally friendly production process with high costs. The plant fiber source (e.g., maize silage) has become a common practice to reduce the cost during the fattening period to gain more profit, which means a precision feed component is needed in ecological pig-raising systems (EPRS) for achieving the balance between environment and economic profit. This manuscript provided a suitable and easy-operated ratio of sun-dried maize silage added to the feed. Meanwhile, we tried to reveal the trends of the pig growth, environmental impacts, and economic profits with the sun-dried maize silage percentage and raising period increasing. Results showed that the best balance point between environmental impact and economic performance was 20% sun-dried maize silage added to the feed with a 360-day raising period.

Abstract

Ecological pig-raising systems (EPRSs) differ from conventional breeding systems, focusing more on environmental consequences, human health, and food safety during production processes. Thus productions from EPRSs have undergone significant development in China. Thus far, adding plant fiber sources (e.g., sweet potato leaves, maize or wheat straw, potato, alfalfa, and vinasse) to feed has become a common practice to reduce the cost during the fattening period. Under such a context, it is necessary to choose the precision EPRS diet components and fattening period with low environmental consequences and high economic benefits. This study set up a database via pig growth models to predict environmental and economic performance based on two trials with 0%, 10%, 40%, 60%, and 80% maize silage (dry weight) added to the feed. A continuous curve about plant fiber concentration was built through the generated database. Our results showed that, with increased plant fiber concentration, the environmental performance of the EPRSs exhibited an “increase-decrease-increase” trend, and the economic performance firstly increased and then decreased. The best maize silage added percentages of emergy yield ratio (EYR), environmental loading ratio (ELR), unit emergy value (UEV), and emergy sustainability index (ESI), and the economic profits were 19.0%, 34.3%, 24.6%, 19.9%, and 18.0%, respectively. Besides, the 19.9% sun-dried maize silage added to the feed with a 360-day raising period had the best balance for environmental impact and economic performance. At the balance point, the performances of EYR, ELR, UEV, ESI, and the economic profit were only 0.04%, 3.0%, 0.8%, 0.0%, and 0.1%, respectively, lower than their maximum values. Therefore, we recommended the feed added 20% sun-dried maize silage is suitable for practical pig raising systems.

Conversion of Carbohydrates in Lignocellulosic Biomass after Chemical Pretreatment

The aim of the study was to determine the quantitative and qualitative changes taking place in biomass components actively participating in methane fermentation, i.e., in carbohydrates, as a result of chemical pretreatment. Analyses were conducted on agricultural waste (corn stover, also called corn straw, and corncobs) as materials most commonly used in methane fermentation, as well as poplar wood, a material relatively rarely used in biogas production. Pretreatment with the aim of increasing efficiency of methane fermentation was carried out with the use of acid and alkaline solutions of different concentrations. The effect of pretreatment on carbohydrates was analyzed based on the quantitative and qualitative changes in this component. Due to the structural heterogeneity of carbohydrates, their varied reactivity and fermentability were determined in terms of holocellulose, cellulose, and pentosans. The chemical structure of cellulose was also analyzed. It is shown in this study that chemical pretreatment causes transformations of carbohydrate components, which differ quantitatively and qualitatively in the compared raw materials. It was found that the alkaline treatment caused smaller changes in the percentage shares of the carbohydrate biomass components as compared to the acid treatment. Moreover, it was observed that the compared materials differ in terms of quantitative changes in their chemical composition depending on the composition of the raw material prior to pretreatment. In the case of corn waste subjected to the action of 1 and 3% NaOH, the share of pentosans in the biomass increased. It was established that this is a change with a positive effect on fermentation efficiency. The action of acids and alkalis on the biomass led to similar structural changes in cellulose, which are adverse for the fermentation process.

Emergy-Based Sustainability Analysis of an Ecologically Integrated Model with Maize Planting for Silage and Pig-Raising in the North China Plain

The structure of the pig-raising sector in China is changing towards large-scale and intensive systems or ecological pig-raising systems (EPRSs). To choose the best EPRS with high economic benefits and with low environmental consequences, this study combined economic analysis and emergy analysis methods to evaluate several EPRSs. Having a large percentage of maize silage in the feed (max 40%) to replace some maize increased the economic benefit and sustainability of the EPRS and decreased the pressure on the environment. The raising system that consisted of Tuhe black pigs fed feed containing maize silage (EPRS C) performed especially well. The yield-based economic profit and area-based economic profit of EPRS C increased by 37%–54% and 3%–17%, respectively, compared to those of the three-breed crossbred pig-raising systems with or without maize silage added to the feed (EPRS A and EPRS B). Its unit emergy value and emergy loading ratio were 9–22% and 10–15% lower, respectively, than those of EPRS A and EPRS B. Furthermore, its emergy yield ratio and emergy sustainability index were about 2% and 14%–19% higher, respectively, than those of EPRS A and EPRS B. To some extent, the results from EPRS C give some guidelines on improving the performance of the ecological pig-raising sector in China. Moreover, using a high concentration of maize silage in the feed and an optimal local pig type may be beneficial for the sustainability of the ecological pig-raising sector in China.