Sodium metabisulphite enhances energy utilisation in broiler chickens offered sorghum-based diets with five different grain varieties

Effects of deoxynivalenol and sodium meta-bisulphite on nutrient digestibility in growing pigs

Deoxynivalenol (DON), a mycotoxin synthesised by the Fusarium, is known to affect the growth of pigs. This effect can be attenuated with sodium meta-bisulphite (SBS). The aim of this study was to evaluate the effect of SBS with antioxidant blend on nutrient digestibility in pigs fed a diet contaminated naturally with DON. Six crossbred castrated pigs fitted surgically with single-T cannulas in the distal ileum received one of four barley-corn-soybean diets with or without SBS. After 8 d of feeding, faeces and ileal digesta were collected for 2 d. Apparent ileal digestibility (AID) of the dry matter (DM), energy, nutrients and DON, and apparent total tract digestibility (ATTD) of DM, acid detergent fibre (ADF), neutral detergent fibre (NDF), energy and DON were evaluated. The AID of phosphorus, calcium and some amino acids was increased (p < 0.05) in the DON diets whereas the ATTD of DM and energy tended to decrease (p = 0.064 and p = 0.071). SBS reduced the AID of DM, energy, ADF, ether extract, phosphorus and DON (p < 0.05) but had no effect on the ATTD of DM, energy, fibre or DON. These results show that DON improved the AID of some nutrients but tended to reduce the ATTD of energy, which could explain, although anorexia is the main effect of DON on live weight gain, the reported negative effect of DON on pig growth. Finally, SBS with antioxidant blend had reduced AID of some nutrients and intestinal absorption of DON.

Long-term anaerobic conservation of fruit and vegetable discards without or with moisture adjustment after aerobic preservation with sodium metabisulfite

The high moisture and soluble carbohydrates contents of fruit and vegetable discards accelerate putrefaction; thus, the immediate use of preservatives is necessary to prevent their decay and allow further use. Two series of experiments were performed to evaluate the conservation stability of fruit and vegetable discards through ensiling. Fruit and vegetable discards were not treated or treated with 6 g sodium metabisulfite/kg fruit and vegetable discards and aerobically challenged for 7 days. In Experiment 1, sodium metabisulfite-treated fruit and vegetable discards were ensiled alone as high-moisture biomass. Silage fermentation was not effective in preventing the deterioration and mold control, which resulted in the rapid depletion of sugars and dry matter loss in control silage (without sodium metabisulfite). Conversely, the low number of undesirable microorganisms resulted in the negligible loss of nutrients in the sodium metabisulfite-treated silage. In Experiment 2, sodium metabisulfite-treated fruit and vegetable discards were co-ensiled with dry by-product feeds at varying proportions to provide sodium metabisulfite loads of 1.6, 2.4, 3.2, and 4 g/kg biomass. Based on microbiological, nutrient composition, and organoleptic evaluations, the sodium metabisulfite load of 3.2 g/kg biomass provided the most desirable conservation parameters. This study provides a clean route to the safe utilization of the discards for a prolonged period, with negligible dry matter and nutrient loss.

Outlook: Sorghum as a feed grain for Australian chicken-meat production

This review is an outlook for sorghum as a feed grain for broiler chickens based on a survey of relevant stake-holders and recent research outcomes. Australian grain sorghum production will probably continue to generate a harvest in the order of 2.5 × 106 t of which some 7.9 × 105 t will be used as a feed grain for poultry and pigs. Feed grains are included primarily to provide energy from starch, but energy utilisation by broiler chickens offered sorghum-based diets is relatively inferior, because of incomplete starch digestion. Kafirin, the dominant protein fraction, 'non-tannin' phenolic compounds and phytate are 3 'starch extrinsic' factors in sorghum that compromise starch digestibility and energy utilisation in broiler chickens offered sorghum-based diets. Kafirin concentrations in 6 sorghum varieties were negatively correlated with metabolizable energy to gross energy (ME:GE) ratios (r = -0.891; P < 0.02) or the efficiency of energy utilisation in broiler chickens. Importantly, kafirin proportions of sorghum protein may be increasing with time in Australia. If so, this represents a fundamental challenge to sorghum breeders which presumably could be met by the development of sorghum varieties with different characteristics, especially in relation to the γ- and β-kafirin fractions. White sorghum varieties contain lower polyphenol concentrations which should be advantageous as concentrations of total phenolic compounds were negatively correlated to ME:GE ratios (r = -0.838; P < 0.04) in 6 sorghum varieties. It would be desirable if more white varieties were to become available. It is suggested that responses to exogenous phytase in birds offered sorghum-based diets would be more robust if sorghum were to contain lower concentrations of kafirin and phenolic compounds. Paradoxically, while better sorghum varieties almost certainly could be developed, it may not necessarily follow that they will command a price premium from poultry and pig producers.

The potential of rapid visco-analysis starch pasting profiles to gauge the quality of sorghum as a feed grain for chicken-meat production

Thirteen extensively characterised grain sorghum varieties were evaluated in a series of 7 broiler bioassays. The efficiency of energy utilisation of broiler chickens offered sorghum-based diets is problematic and the bulk of dietary energy is derived from sorghum starch. For this reason, rapid visco-analysis (RVA) starch pasting profiles were determined as they may have the potential to assess the quality of sorghum as a feed grain for chicken-meat production. In review, it was found that concentrations of kafirin and total phenolic compounds were negatively correlated with peak and holding RVA viscosities to significant extents across 13 sorghums. In a meta-analysis of 5 broiler bioassays it was found that peak, holding, breakdown and final RVA viscosities were positively correlated with ME:GE ratios and peak and breakdown RVA viscosities with apparent metabolizable energy corrected for nitrogen (AMEn) to significant extents. In a sixth study involving 10 sorghum-based diets peak, holding and breakdown RVA viscosities were positively correlated with ME:GE ratios and AMEn. Therefore, it emerged that RVA starch pasting profiles do hold promise as a relatively rapid means to assess sorghum quality as a feed grain for chicken-meat production. This potential appears to be linked to quantities of kafirin and total phenolic compounds present in sorghum and it would seem that both factors depress RVA starch viscosities in vitro and, in turn, also depress energy utilisation in birds offered sorghum-based diets. Given that other feed grains do not contain kafirin and possess considerably lower concentrations of phenolic compounds, their RVA starch pasting profiles may not be equally indicative.

Reducing agent and exogenous protease additions, individually and in combination, to wheat- and sorghum-based diets interactively influence parameters of nutrient utilisation and digestive dynamics in broiler chickens

The objective of the study was to investigate the possibility that tandem inclusions of a reducing agent and a protease may advantage chicken-meat production and to ascertain if the established benefits of including sodium metabisulphite in sorghum-based diets extend to wheat-based diets. The study comprised a 2 × 2 × 2 factorial array of treatments in which either nutritionally iso-nitrogenous and iso-energetic wheat- or sorghum-based diets, without and with sodium metabisulphite (2.75 g/kg), without and with protease (1,000 units/kg) were offered to broiler chickens from 7 to 28 days post-hatch. The effects of dietary treatments on growth performance, nutrient utilisation, protein (N) and starch digestibility coefficients and digestive dynamics were determined. A preliminary investigation into the effects of two treatments on concentrations of free amino acids and glucose in the portal circulation was conducted. There was significant feed grain by sodium metabisulphite interactions (P = 0.03 to 0.005) for parameters of nutrient utilisation (AME, ME:GE ratios, N retention, AMEn). For example, sodium metabisulphite inclusions in sorghum-based diets enhanced AME by 0.18 MJ (12.47 versus 12.29 MJ/kg) but depressed AME by 0.43 MJ (11.88 versus 12.31 MJ/kg) in wheat-based diets. There was a linear relationship between starch:protein disappearance rate ratios in the distal ileum with weight gain (r = -0.484; P = 0.0012) indicating that condensed ratios (or absorption of more protein relative to starch) advantaged growth performance. Concentrations of free amino acids in the portal circulation or the post-enteral availability of certain amino acids, including the branched-chain amino acids, methionine, phenylalanine and threonine, were significantly correlated to FCR. For example, threonine concentrations were negatively correlated to FCR (r = -0.773; P = 0.005). Finally, tandem inclusions of sodium metabisulphite and protease in sorghum-based diets may hold merit but it appears that the established 'energy sparing' effects of sodium metabisulphite inclusions in sorghum-based diets are not duplicated in wheat-based diets.