Use of duckweed, bentonite and acid to improve water quality of effluent discharge from abattoirs

Intensive animal industries create large volumes of nutrient rich effluent, which, if untreated, has the potential for substantial environmental degradation. Aquatic plants in aerobic lagoon systems have the potential to achieve inexpensive and efficient remediation of effluent, and to recover valuable nutrients that would otherwise be lost. Members of the family Lemnaceae (duckweeds) are widely used in lagoon systems, but despite their widespread use in the cleansing of sewage, only limited research has been conducted into their growth in highly eutrophic media, and little has been done to systematically distinguish between different types of media. This study examined the growth characteristics of duckweed in abattoir effluent, and explored possible ways of ameliorating the inhibitory factors to growth on this medium. A series of pot trials was conducted to test the tolerance of duckweed to abattoir effluent partially remediated by a sojourn in anaerobic fermentation ponds, both in its unmodified form, and after the addition of acid to manipulate pH, and the addition of bentonite. Unmodified abattoir effluent was highly toxic to duckweed, although duckweed remained viable and grew sub optimally in media with total ammonia nitrogen (TAN) concentrations of up to 100 mg/l. Duckweed also grew vigorously in effluent diluted 1:4 v/v, containing 56 mg TAN/L and also modified by addition of acid to decrease pH to 7 and by adding bentonite (0.5%).

Total and phytate-phosphorus contents and phytase activity of Australian-sourced feed ingredients for pigs and poultry

A total of 160 samples of 20 Australian-sourced feed ingredients of plant origin for pigs and poultry was analysed for total phosphorus and phytate-phosphorus contents and endogenous phytase activity. The majority of total P was present as phytate-phosphorus, and these concentrations were significantly correlated in 9 feed ingredients. The endogenous phytase activity in tested feed ingredients was negligible other than for wheat, its by-products and barley. Phytate-phosphorus was determined by a standard 'ferric chloride precipitation' method, which was satisfactory for individual feed ingredients, with the exception of lupins and faba beans. It appears that phytate is more difficult to extract from these two feedstuffs, possibly because of the affinity of phytate for protein. Ferric chloride precipitation methods are not suitable for phytate-phosphorus determinations of complete feed samples containing other sources of phosphorus, which is a distinct limitation. A lesser limitation is that these methods cannot distinguish between the various esters of myo-inositol phosphate present. Given the variation of phytate contents within ingredients, particularly wheat, the desirability of determining dietary substrate levels is emphasised to take full advantage of including exogenous phytases in pig and poultry diets to reduce phosphorus excretion and abate phosphorus pollution.

Ileal digestibility of amino acids in feed ingredients for broilers.

To more precisely formulate feed and predict animal performance, it is important to base both the recommendations and feed formulations on digestible rather than total amino acid contents. Most published data on the digestibility of amino acids in feed ingredients for poultry are based on excreta digestibility. Ileal digestibility is an alternative and preferred approach to estimate amino acid availability in feed ingredients. Both methodologies are described and assessed. In addition, the differences between apparent and standardised (in which corrections are made for basal endogenous losses) digestible amino acid systems are discussed. The concept of a standardised digestibility system as a mean of overcoming the limitations of apparent digestibility estimates is proposed. In this context, different methodologies for the determination of basal endogenous amino acid losses are discussed. Although each methodology suffers from some limitations and published data on endogenous losses at the ileal level in growing poultry are limited, averaged data from repeated experiments using the 'enzymatically hydrolysed casein' method are considered as the best measure of basal losses. Standardised ileal amino acid digestibility values of 17 feed ingredients commonly used in broiler nutrition are presented including grains (barley, corn, sorghum, triticale, wheat), grain by-products (wheat middlings, rice pollard), plant protein sources (soybean meal, canola meal, corn gluten meal, cottonseed meal, lupins, peas/beans, sunflower meal), and animal by-products (feather meal, fish meal, meat and bone meal). This comprehensive set of the ileal amino acid digestibility of feed ingredients in broiler nutrition may serve as a basis for the establishment of the system in broiler feeding and for further research.

Matching poultry production with available feed resources: issues and constraints

Corn and soyabeans may not be available in many countries particularly those which do not have sufficient foreign currency or the capacity to grow them. This paper outlines strategies that may be important under these circumstances. Alternative feedstuffs and various feeding systems may be used to support poultry production. Alternative ingredients such as rice bran, pearl millet, cottonseed meal and grain legumes are discussed. Evidence is presented showing that amino acid requirements of layers and broilers may be too generous particularly in countries where climate, management and disease can impose production constraints. The ability of finishing broilers to perform well on very low-energy diets allows the inclusion of alternative feeds and by-products into formulations. Very low protein diets based on cereals and free amino acids can be used for layers without loss of performance. Self-selection of feedstuffs may be an important strategy in reducing feed costs of broilers and layers. The concept of matching production with available feed resources may compromise broiler growth and egg production, but in many countries this may be the most economical choice. Countries in the humid tropics usually have reduced poultry performance. The effects of high temperature and humidity are difficult to overcome. The vexed questions of the escalation in the price of fossil fuel and the outbreak of avian influenza, both seemingly without a solution, are clouds hanging over an otherwise buoyant industry.

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.

Development of an animal repellent - selection, efficacy and presentation

Under some circumstances it may be desirable to repel herbivorous pests (e. g. goats and wallabies) from plants (e. g. horticultural or forestry seedlings) rather than to kill them. These circumstances may include using these animals as a resource at a later time, and there may also be welfare, public perception or legislative issues where repelling animals from particular plants or area is preferable to killing them. The first experiment tested the efficacy of 5 different materials (tiger fecal extract, maggot brew-the liquid exudate from a flyblown goat, capsaicin, dog urine, and burnt goat hair, skin and carcass+fat) to repel groups of goats in a feedlot pen from 1 trough of feed when another trough of feed was available to them to eat. Each repellent was tested on 5 groups of mixed age female goats for periods of 3 days. All 5 groups were exposed to the 5 repellents. Both tiger fecal extract and maggot brew reduced intake of feed from the 'protected' feed trough and significantly (P < 0.05) delayed 'normal' feeding behaviour by more than 5 h from that trough. The repellents became less effective with repeated use even with different groups of goats. The reduction in effectiveness was indicated by higher intakes of feed and earlier feeding from the protected trough. This habituation to the repellents, where the effectiveness is reduced with repeated exposure, is of concern. In the second experiment, we selected the most effective repellent (tiger fecal extract) and tested its efficacy under similar conditions, after the repellent had been mixed with a carrier (bentonite) in an endeavour to increase the duration of its effectiveness. This repellent was significantly more effective in repelling groups of 3 goats in a feedlot pen from 1 trough of feed for 3 days, when another trough of feed was available to them to eat.

Water balance in goats subjected to feed restriction

The effect of feed restriction on water balance and nutrient utilization was investigated in individually penned Boer x Saanen kids. Twenty-two male Boer x Saanen kids with an initial average live weight (LW) of 15 kg were used. Seven kids were slaughtered at the beginning of the experiment (reference animals) and the remainders were allocated to one of the three treatments (0, 30 and 60% restriction) and therefore there were five kids per treatment. The feed intake for the 0% restriction treatment animals determined the intake for the animals in the 30 and 60% restriction treatment. When the animals in the 0% restriction treatment group reached 25 kg LW, the animals in the 30 and 60% restriction treatment groups were also slaughtered. There was a negative relationship between DMI and water intake. The digestibility coefficients for DM, OM, carbohydrates, ash, ether extract, energy, NDF, ADF and lignin did not differ between treatments, whereas the digestibility coefficient for CP was different between treatment groups. The highest metabolic water production was in animals in the 0% restriction treatment group. No significant differences were observed in the composition of gastro-intestinal tract contents of the goats in the different treatments. Lower water retention was found in the animals in the 60% restriction treatment group. The study showed that feed restriction affected water intake, CP digestibility and water retention in the body of the kid goats. This experiment demonstrated that DM:water intake ratio changed when severe feed restriction was applied (60% restriction) and water was freely available. It shows a different pattern of behaviour of penned goats, particularly if feed intake is restricted and perhaps caution is needed to extrapolate results from nutritional and physiological trials in pens to goats at pasture. (c) 2005 Elsevier BX All rights reserved.