Potential of Using Maize Cobs in Pig Diets - A Review.

The quest to broaden the narrow range of feed ingredients available to pig producers has prompted research on the use of low cost, unconventional feedstuffs, which are typically fibrous and abundant. Maize cobs, a by-product of a major cereal grown worldwide, have potential to be used as a pig feed ingredient. Presently, maize cobs are either dumped or burnt for fuel. The major challenge in using maize cobs in pig diets is their lignocellulosic nature (45% to 55% cellulose, 25% to 35% hemicellulose, and 20% to 30% lignin) which is resistant to pigs' digestive enzymes. The high fiber in maize cobs (930 g neutral detergent fiber/kg dry matter [DM]; 573 g acid detergent fiber/kg DM) increases rate of passage and sequestration of nutrients in the fiber reducing their digestion. However, grinding, heating and fermentation can modify the structure of the fibrous components in the maize cobs and improve their utilization. Pigs can also extract up to 25% of energy maintenance requirements from fermentation products. In addition, dietary fiber improves pig intestinal health by promoting the growth of lactic acid bacteria, which suppress proliferation of pathogenic bacteria in the intestines. This paper reviews maize cob composition and the effect on digestibility of nutrients, intestinal microflora and growth performance and proposes the use of ensiling using exogenous enzymes to enhance utilization in diets of pigs.

Growth performance, blood metabolic responses, and carcass characteristics of grower and finisher South African Windsnyer-type indigenous and Large White×Landrace crossbred pigs fed diets containing ensiled corncobs.

A study was taken to evaluate growth performance, carcass characteristics, and blood metabolite concentrations when ensiled corncobs were included in indigenous and commercial pig diets. Fifty Large White× Landrace (LW×LR) crossbred pigs and 30 South African Windsnyer-type indigenous pigs (SAWIP) were evaluated. They were fed a control (CON), a low inclusion of ensiled corncob (LMC), and a high inclusion of ensiled corncob (HMC) diet in a completely randomized block design. The LW×LR crosses had greater (P<0.05) final weight, ADFI, DMI, ADG, and G:F ratios than the SAWIP at both the grower and finisher stages. The SAWIP consumed more feed per metabolic BW (BW0.75) than LW×LR crosses at the grower stage while LW×LR crosses consumed more than SAWIP at the finisher stage (P<0.05). The finishers' G:F ratio was greater (P<0.05) in the CON than in the HMC diet. The LW×LR growers and finishers had greater (P<0.05) warm carcass weight (WCW), cold carcass weight (CCW), carcass length, drip loss, pH at 24 h, eye muscle area, and lean percent than those of SAWIP growers and finishers. The LW×LR finishers on the CON diet had greater (P<0.05) WCW and CCW than those on the HMC and LMC diets. There were diet×breed interactions for dorsal fat thickness at first rib (DFT1), dorsal fat thickness at last lumbar vertebra (DFT3), backfat thickness (BFT), and hindquarter weight proportion (HQWP) in the growers. The LW×LR growers and finishers had greater values (P<0.05) of hindquarter length, hindquarter circumference, HQWP, and shoulder weight proportion than the SAWIP growers and finishers, respectively. The SAWIP growers and finishers had greater values (P<0.05) of DFT1, dorsal fat thickness at last rib, DFT3, and BFT than the LW×LR growers and finishers, respectively. There were breed×diet interactions (P<0.05) for alanine aminotransferase and amylase (AMYL). The LW×LR crosses had greater (P< 0.05) values of creatinine, phosphorus, alkaline phosphatase, cholesterol, and AMYL than the SAWIP. The breed of pig influenced most of the growth performance and carcass parameters more than the diet did. There was no clear link between the blood metabolite levels and the diets. Since the inclusion of ensiled corncobs in diets did not affect negatively the selected important commercial pork cuts in South Africa, this could imply that they have a greater role as a pig feed resource.

Model plant systems in salinity and drought stress proteomics studies: a perspective on Arabidopsis and Sorghum.

More than a decade after the sequencing of its genome, Arabidopsis still stands as the epitome of a model system in plant biology. Arabidopsis proteomics has also taught us great lessons on different aspects of plant growth, development and physiology. Without doubt our understanding of basic principles of plant biology would not have been this advanced if it were not for knowledge gained using Arabidopsis as a model system. However, with the projections of global climate change and rapid population growth, it is high time we evaluate the applicability of this model system in studies aimed at understanding abiotic stress tolerance and adaptation, with a particular emphasis on maintaining yield under hot and dry environmental conditions. Because of the innate nature of sorghum's tolerance to drought and moderate tolerance to salinity stresses, we believe sorghum is the next logical model system in such studies amongst cereals. In this acute view, we highlight the importance of Arabidopsis as a model system, briefly discuss its potential limitations in drought and salt stress studies, and present our views on the potential usefulness of sorghum as a model system for cereals in drought and salinity stress proteomic studies.

Proteomic analysis of the Arabidopsis cell wall reveals unexpected proteins with new cellular locations.

We initiated a proteomic study as part of a programme aimed at discovering novel functions of the plant cell wall. Cell-wall fragments isolated from cell-suspension cultures of Arabidopsis thaliana were stripped of protein sequentially using CaCl2 and a urea-based buffer. The protein fractions were separated by two-dimensional gel electrophoresis and individual proteins were identified by MS. We identified a number of proteins considered to be resident in other organelles but not the cell wall on the basis of their classical biological function. These included citrate synthase, which is known to be targeted to mitochondria, peroxisomes and glyoxysomes, and luminal binding protein, which is an ER (endoplasmic reticulum)-resident protein. Searches of the Arabidopsis database revealed that there are several genes encoding putative citrate synthase and luminal binding protein. We have also performed detailed analyses of the protein sequences and this paper shows how each one contains encrypted targeting information that results in the export of the protein to the extracellular matrix. We discuss the presence of alternative non-classical secretory pathways in plants.