Biogenic amines in Australian animal by-product meals

Biogenic amines were determined in Australian by-product meals including fish meals, poultry meals, meat meals, feather meals and blood meals. They were extracted with 0.1 mol/L HCl, derivatised with dansyl chloride and analysed using HPLC with UV detection at 254 nm. Median levels of putrescine, cadaverine and histamine were determined in the by-product meals, with the ranges being 13-102 mg/kg, 7-220 mg/kg and 4-570 mg/kg, respectively. High levels of biogenic amines were found particularly in fish meals. The results indicate that further studies are required to determine the maximum limits for biogenic amines in by-product meals that will not impair production when fed to poultry.

Effects of phytase supplementation of diets with two tiers of nutrient specifications on growth performance and protein efficiency ratios of broiler chickens

in two feeding experiments male and mixed-sex broiler chicks were offered diets based on sorghum and a wheat-sorghum blend with two tiers of nutrient specifications, without and with microbial phytase (600 and 800 FTU/kg), from 7-25 and 1-42 days post-hatch, respectively. The nutrient specifications for protein, amino acids, energy density and phosphorus (P) of standard diets were reduced to formulate the modified diets on a least-cost basis. Calculated differences in nutrient specifications between standard and modified diets ranged from 14.3 to 17.1 g/kg crude protein, 0.24 to 0.40 MJ/kg apparent metabolisable energy (AME) and 1.06 to 1.20 g/kg available P. In both experiments, reduced nutrient specifications had a negative impact on growth rates and feed efficiency and phytase supplementation had a positive influence on growth performance and protein efficiency ratios (PER). Phytase addition to the less expensive, modified diets either partially or entirely compensated for reduced growth performance and, consequently, feed costs per kg of live weight gain were reduced. In Experiment 1, phytase increased (p<0.001) nitrogen-corrected AME (AMEn) from 15.39 to 15.89 MJ/kg dry matter. For nitrogen (N) retention there was an interaction (p<0.05) between diet type and phytase as the effects of phytase on N retention were more pronounced in the modified diets, with an increase from 0.512 to 0.561. These results demonstrate the positive effects of phytase on protein and energy utilisation, in addition to its established liberation of phytate-bound P and illustrate the feasibility of assigning nutrient replacement values to the feed enzyme for consideration in least-cost ration formulations. Further work is, however, required to define the most appropriate reductions in nutrient specifications in association with phytase supplementation.

Investigation of ansB and sspA derived promoters for multi- and single-copy antigen expression in attenuated Salmonella enterica var. typhimurium

Five candidate promoters were examined to determine their utility in directing immunogenic levels of expression of the C fragment from tetanus toxin in attenuated S. enterica used as an oral vaccine in mice. Promoters derived from the genes encoding the stringent starvation protein (sspA) from E. coli and S. enterica, but not ansB derived promoters, expressed immunogenic levels of C fragment from multi-copy plasmids in attenuated S. enterica in vivo and, following oral immunization, induced high titre specific anti-tetanus toxoid serum antibodies. We also demonstrate that not only the choice of promoter, replicon and growth conditions but also how expression constructs are assembled in the chosen plasmid is critical for the successful development of plasmid-based antigen delivery systems using attenuated S. enterica. In addition, the S. enterica sspA promoter is able to elicit anti-tetanus toxoid antibodies in mice when the psspA-tetC expression cassette is integrated in single copy on the S. enterica chromosome.

The influence of dietary sodium chloride, Arginine : Lysine ratio, and methionine source on apparent ileal digestibility of arginine and lysine in acutely heat-stressed broilers

The present study was carried out to determine the ileal digestibility of Arg and Lys in acutely heatstressed broilers using diets varying in Arg:Lys ratio, NaCl concentration, and Met Source. Male broilers were maintained at 22degreesC from 21 to 33 d of age and then at 32degreesC from 33 to 38 d of age. From 28 to 38 d of age, birds were fed a diet with an Arg:Lys ratio of 1.05 and 3 g of supplemental NaCl/kg of diet with or without L-arg free base to increase the Arg:Lys to 1.35, and with or without 3 g/kg of additional NaCl. Methionine was supplied as equimolar amounts of DL-Met or 2-hydroxy-4-(methylthio)-butanoic acid in a 2 x 2 x 2 design. At 38 d of age, digesta were collected from the terminal ileum, and amino acid analyses were conducted on feed and digesta samples and compared with acid-insoluble ash (dietary celite) to calculate the apparent ileal digestibilities of Lys and Arg. Increasing the NaCl concentration and the presence of HMB significantly decreased the digestibility of both Arg and Lys, whereas increasing the Arg:Lys ratio increased the digestibility of only Arg but did increase BW gain (P = 0.08). An interaction between dietary NaCl and Arg:Lys ratio as well as the 3-way interaction suggested that dietary NaCl could affect the apparent ileal digestibility of Arg and Lys at certain Arg:Lys ratios and the response may be influenced by the Met source.

Analysis of the Pasteurella multocida outer membrane sub-proteome and its response to the in vivo environment of the natural host

This study describes the identification of outer membrane proteins (OMPs) of the bacterial pathogen Pasteurella multocida and an analysis of how the expression of these proteins changes during infection of the natural host. We analysed the sarcosine-insoluble membrane fractions, which are highly enriched for OMPs, from bacteria grown under a range of conditions. Initially, the OMP-containing fractions were resolved by 2-DE and the proteins identified by MALDI-TOF MS. In addition, the OMP-containing fractions were separated by 1-D SDS-PAGE and protein identifications were made using nano LC MS/MS. Using these two methods a total of 35 proteins was identified from samples obtained from organisms grown in rich culture medium. Six of the proteins were identified only by 2-DE MALDI-TOF MS, whilst 17 proteins were identified only by 1-D LC MS/MS. We then analysed the OMPs from P. multocida which had been isolated from the bloodstream of infected chickens (a natural host) or grown in iron-depleted medium. Three proteins were found to be significantly up-regulated during growth in vivo and one of these (Pm0803) was also up-regulated during growth in iron-depleted medium. After bioinformatic analysis of the protein matches, it was predicted that over one third of the combined OMPs predicted by the bioinformatics sub-cellular localisation tools PSORTB and Proteome Analyst, had been identified during this study. This is the first comprehensive proteomic analysis of the P. multocida outer membrane and the first proteomic analysis of how a bacterial pathogen modifies its outer membrane proteome during infection.

Biological response of broiler chickens fed peas (Pisum sativum L.) expressing the bean (Phaseolus vulgaris L.) alpha-amylase inhibitor transgene

The nutritive value of transgenic peas expressing an a-amylase inhibitor (alpha-Ail) was evaluated with broiler chickens. The effects of feeding transgenic peas on the development of visceral organs associated with digestion and nutrient absorption were also examined. The chemical composition of the conventional and the transgenic peas used in this study were similar. In the two feeding trials, that were conducted normal and transgenic peas were incorporated into a maize-soybean diet at concentrations up to 500 g kg(-1). The diets were balanced to contain similar levels of apparent metabolisable energy (AME) and amino acids. In the first trial, the birds were fed the diets from 3 to 17days post-hatching and with levels of transgenic peas at 250 g kg(-1) or greater there was a significant reduction in body weight but an increase in feed intake resulting in deceased feed conversion efficiency. In the second trial, in which the birds were fed diets containing 300 g kg(-1) transgenic peas until 40 days of age, growth performance was significantly reduced. It was also demonstrated that the ileal starch digestibility coefficient (0.80 vs 0.42) was significantly reduced in the birds fed transgenic peas. Determination of AME and ileal digestibility of amino acids in 5-week-old broilers demonstrated a significant reduction in AME (12.12 vs 5.08 MJ kg(-1) DM) in the birds fed the transgenic peas. The AME value recorded for transgenic peas reflected the lower starch digestibility of this line. Real digestion of protein and amino acids was unaffected by treatment. Expression of a-Ail in peas did not appear to affect bird health or the utilisation of dietary protein. However, the significant reduction in ileal digestion of starch in transgenic peas does reduce the utility of this feedstuff in monogastric diets where efficient energy utilisation is required. (c) 2006 Society of Chemical Industry.

Palm kernel meal in broiler diets: effect on chicken performance and health

An increase in the production of palm kernel meal (PKM) coupled with the concern for continued availability of conventional feedstuffs in some parts of the world has led to research to establish the maximum inclusion level of palm kernel meal in broiler diets. The results suggested that palm kernel meal has no anti-nutritional properties and thus its inclusion is safe up to at least 40% in the diet, provided the diet is balanced in amino acids and metabolisable energy. Although feed digestibility is decreased due to high dietary fibre when PKM is included in the diet, the feed intake is increased. This makes total digestible nutrient intake relatively high. beta-mannan is the main component of palm kernel meal non-starch polysaccharide (NSP). Both mannose and manno-oligosaccharides have been reported to act as prebiotics. The inclusion of palm kernel meal in the diet improves the immune system of birds and reduces pathogenic bacteria and increases the population of nonpathogenic bacteria in the intestine. These two benefits should be considered as strong recommendations for using palm kernel meal in broiler diets, particularly in palm kernel meal producing countries, not only for increasing bird productivity but also to improve chicken health. Selective enzyme addition increases feed efficiency and digestibility as well as decreasing the moisture content of faeces.

Total and ileal digestible tryptophan contents of feedstuffs for broiler chickens

Reliable values of total and digestible tryptophan in components of feed formulation matrices are needed because tryptophan is often the third limiting amino acid in practical poultry diets. However, tryptophan is oxidatively destroyed during acid hydrolysis in routine amino acid analysis and its determination requires a separate analytical procedure. The variability in contents and apparent ileal digestibility for 6-week-old broiler chickens of tryptophan in 74 samples representing 24 feedstuffs are presented in this paper. The average ileal tryptophan digestibility coefficient in wheat was 0.83, in sorghum and triticale 0.75, maize 0.71, soybean meal 0.84, sunflower meal 0.81, canola meal 0.78 and cottonseed meal 0.75. Among the grain legumes, tryptophan in lupins was better digested than that in chickpeas, fababeans and field peas. Among the animal protein meals, the tryptophan digestibility coefficients in fish meal (0.77) and blood meal (0.84) were substantially higher than those in meat meal (0.64), meat-and-bone meal (0.63) and feather meal (0.52). Marked variations in tryptophan digestibility were also observed among samples of fish meal, meat-and-bone meal and meat meal, highlighting significant batch-to-batch differences. For most feedstuffs, considerable variability was observed in the tryptophan concentrations, but such variations were not reflected in digestibility coefficients. (c) 2006 Society of Chemical Industry.

The effect of xylanase, phytase and lipase supplementation on the performance of broiler chickens fed a diet with a high level of rice bran.

Enzyme products did not have a significant effect (P>0.05) on weekly fed intake and weight gain of birds. But feed intake tended to drop and weight gain tended to increase in response to supplementation of the three enzymes. Weight gain of the birds was increased by 0.6% with lipase, 3.7% with phytase and 2.4% with xylanase. Xylanase had a marked effect (P