SADC planning workshop on Newcastle Disease control in village chickens : Maputo, Mozambique, 6-9 March, 2000

This publication is a record of papers presented at a workshop in Maputo, Mozambique 6-9 March, 2000 on Newcastle disease in village chickens. A thermostable vaccine suitable for use in the control of Newcastle Disease in village chickens has been developed by the University of Queensland, with funding from ACIAR

Lysine requirements of pre-lay broiler breeder pullets: Determination by indicator amino acid oxidation

The indicator amino acid oxidation (IAAO) method allows the determination of amino acid requirements under conditions of low growth rate as found in pre-laying broiler breeder pullets. Cobb 500 breeder pullets (20 wk old; 2290 +/- 280 g, n = 4) were adapted (6 d) to a pelleted, purified control diet containing all nutrients at greater than or equal to 110% of NRC recommendations. After recovery from surgery for implantation of a jugular catheter, each bird was fed, in random order, test diets containing one of nine levels of lysine (0.48, 0.96, 1.92, 2.88, 3.84, 4.80, 7.68, 9.60 and 14.40 g/kg of diet). Indicator oxidation was determined during 4-h primed (74 kBq/kg body), constant infusions (44 kBq (.) h(-1) (.) kg body(-1)) of L-[1-C-14]phenylalanine. Using the breakpoint of a one-slope broken-line model, the lysine requirement was determined to be 4.88 +/- 0.96 g/kg of diet or 366 +/- 72 mg (.) hen(-1) (.) d(-1) with an upper 95% Cl of 6.40 g/kg of diet or 480 mg (.) hen(-1) (.) d(-1). IAAO allows determination of individual bird amino acid requirements for specific ages and types of birds over short periods of time and enables more accurate broiler breeder pullet diet formulation.

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.

Endogenous amino acid flow in the avian ileum: quantification using three techniques

The aim of the present study was to compare the protein-free diet, guanidinated casein (GuC) and enzyme hydrolysed casein (EHC) methods for the quantification of endogenous amino acid (AA) flow in the avian ileum. Growing broiler chickens (5 weeks old) were used. All three assay diets were based on dextrose, and in the GuC and EHC diets GuC or EHC were the sole source of N. Endogenous AA flows determined with the use of protein-free diet were considerably lower (P < 0.05) than those determined by the GuC and EHC methods. The, total endogenous AA flows determined by the GuC and EHC methods were almost 3-fold greater (P < 0.05) than those determined by the protein-free diet. The endogenous AA values obtained from GuC and EHC methods were similar (P >0.05), except for the flow of arginine, which was lower (P < 0.05) in the EHC method. Glutamic acid, aspartic acid, threonine and glycine were the predominant endogenous AA present in digesta from the distal ileum. The contents of methionine, histidine and cystine were lower compared with other AA. The method of determination had no effect on the AA composition of endogenous protein, except for threonine, glutamic acid, lysine, arginine and cystine. The concentrations of threonine and arginine were lower (P < 0.05) and that of lysine was higher (P < 0.05) with the EHC method compared with the other two methods. The concentration of glutamic acid was greater (P < 0.05) and that of cystine was lower (P < 0.05) in the EHC and GuC methods compared with the protein-free diet method. The results showed that the ileal endogenous flows of N and AA are markedly enhanced by the presence of protein and peptides, above those determined following feeding of a protein-free diet. It is concluded that the use of EHC and GuC methods enables the measurement of ileal endogenous losses in chickens under normal physiological conditions.

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.

Vaccination against fowl cholera with acapsular Pasteurella multocida A : 1

We have previously constructed an acapsular Pasteurella multocida X-73 (serogroup A) mutant strain which was attenuated in virulence for chickens (Chung JY, Wilkie IW, Boyce JD, Townsend KM, Frost AJ, Ghodussi M, Adler B. Role of capsule in the pathogenesis of fowl cholera caused by Pasteurella multocida serogroup A. Infect. Immun. 2001;69:2487-2492). In this study, we have assessed the ability of this acapsular strain (PBA930) to induce protection against wild-type challenge in mice and the natural host chickens. Intramuscular administration of PBA930 to mice stimulated significant protection against X-73 and the heterologous strain P-1059 (A:3), but not against challenge with P-1662 (A:4). No protection was observed when PBA930 was introduced by the intraperitoneal or subcutaneous routes in mice. Significantly, the acapsular strain PBA930 was able to induce protection against challenge with wild type X-73 in chickens. (c) 2004 Elsevier Ltd. All rights reserved.

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.

Comparison of apparent ileal amino acid digestibility of feed ingredients measured with broilers, layers, and roosters

The apparent ileal digestibility of amino acids in 7 feed ingredients was determined using broilers, layers, and roosters. The ingredients included 3 cereals (wheat, sorghum, and corn), 3 oilseed meals (canola, cottonseed, and soybean meals), and 1 animal protein meal (meat and bone meal). Dietary protein in the assay diets was supplied solely by the test ingredient. All diets contained 20 g/kg of acid-insoluble ash as an indigestible marker, and each diet was offered ad libitum in mash form to 5 replicate pens of broilers and layers, and 4 replicate pens of roosters. The digestibility coefficients of individual amino acids for wheat, corn, and sorghum were higher (P < 0.05) in broilers than in layers and roosters. The digestibility of most amino acids for corn and sorghum was higher (P < 0.05) in roosters compared with those in layers, whereas the digestibility for wheat in layers and roosters was similar. In general, the digestibility of amino acids in canola meal, cottonseed meal, and meat and bone meal was similar among the 3 classes of chickens. The digestibility of amino acids in soybean meal was higher (P < 0.05) for layers compared with those for broilers and roosters but similar between broilers and roosters. These results suggest that the class of chickens significantly influenced the apparent ileal digestibility of amino acids in some feed ingredients.

Effects of artificial foods on the blood chemistry of the Australian magpie

Bird feeding on residential property is a popular activity throughout Western countries. Advocates insist the practice is beneficial, while opponents maintain that it can result in a wide range of negative outcomes including malnutrition. The biological effects of 'backyard feeding' were studied in Australian magpies Gymnorhina tibicen during the non-breeding season in 1999 in the Greater Brisbane and the Lockyer Valley regions, south-east Queensland, Australia. Six magpie populations were selected and 70 birds were individually tagged for identification. The birds were provided with processed foods, 20-40 g per bird daily. To monitor the effects of the food, blood chemistry and body mass (BM) were used as indices. Significant effects were observed in BM and plasma cholesterol (PC), showing strong sensitivity to food provisioning. Significant effects on PC and uric acid were found only when birds were fed dog sausage. Results suggest that blood PC levels in magpies are readily influenced by, probably, the lipids present in food, and that the type of food can affect blood PC levels. These effects may occur widely among fed magpies if the influence that we demonstrated at plasma level can be generalized. Following the free-ranging study, six magpies were captured and subjected to a 6-day captive experiment to determine whether the selected foods had the potential to alter the birds' blood chemistry. It was found that all of the foods, when provided ad libitum, influence at least two of the three blood parameters (PC and non-esterified fatty acids). Due to its popularity, wildlife feeding will continue. To make wildlife-feeding activities truly sustainable, there is a need for further studies. This study clearly demonstrated that the physiology of wild magpies can be affected by 'backyard feeding'.

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.