The replacement of some of the soybean meal by the first limiting amino acids in practical broiler diets. 2. Special additions of methionine and lysine as partial substitutes for protein in finisher diets.

1. Four trials were conducted to determine to what extent dietary protein concentration could be lowered while maintaining the concentrations of methionine and lysine, the first two limiting amino acids. 2. When the protein concentrations of well-balanced standard finisher diets were lowered by replacing soybean meal with sorghum grain (milo), there were progressive decreases in growth rate and increases in food consumption in spite of the substitution raising the energy content of the diets. 3. Maintaining methionine and lysine concentrations partly or completely reversed these trends. 4. Adding 0-12% methionine (above that generally considered to be the normal level in finisher diets) plus 0-20% lysine replace about 3 to 4 percentage units of soybean protein. 5. The recommended level of lysine supplementation may be exaggerated, since preliminary data indicate satisfactory results with a special supplementation of 0-10% each of methionine and lysine.     

Sewage‐grown algae as a source of pigments for broilers

1. Relative utilisations of xanthophylls in young broilers from diets containing meals prepared from the algae Chlorella and Micractinium and alfalfa meal were determined.

2. Relative utilisation was evaluated from plasma and toe‐web xanthophyll contents, and by visual scoring.

3. The results showed poorer xanthophyll utilisation from algae‐containing diets than from alfalfa meal, but algae meals can be used effectively as pigment sources in poultry diets.

     

A proposal of clinical breakpoints for amoxicillin applicable to porcine respiratory tract pathogens

In the present position paper, an attempt was made to establish clinical breakpoints of amoxicillin to classify porcine respiratory tract pathogens as susceptible, intermediate or resistant based on their minimum inhibitory concentrations of amoxicillin. For this, a thorough review of the published literature with regard to swine-specific pharmacological data (including dosages of amoxicillin applied and routes of administration used), clinical efficacy, and in vitro susceptibility of the target pathogens was performed. Based on the comparative analysis of the results, the working group "Antibiotic Resistance" of the German Veterinary Medical Society (DVG) proposed to classify porcine respiratory tract pathogens that show MIC values of amoxicillin of < or =0.5microg/ml as "susceptible", those with MICs of 1microg/ml as "intermediate", and those with MICs of > or =2microg/ml as "resistant".     

Effect of calorie to protein ratio on the degree of fatness in broilers fed on practical diets 1

Three trials were carried out with broilers to compare the effect of different calorie to protein (C : P) ratios in practical‐type diets with the amount of carcass fat at 8 or 9 weeks of age. The latter was estimated on the basis of the concentration of fat or dry matter in a sample of back skin and by visually scoring the amount of abdominal fat.

Rearing broilers on diets containing protein levels slightly above or below the accepted optimum did not affect growth rate. However, in most comparisons the high‐protein diets brought about better food to gain ratios, and in all comparisons they produced relatively lean carcasses. Increasing or decreasing the protein level of finisher diets resulted in a decrease or increase, respectively, in the degree of fatness. A 2‐week period was sufficient to create or reverse these trends in a pronounced manner.

Dietary oil supplementation per se did not increase the amount of carcass fat as long as the C : P ratio was kept constant. If there existed any consistent trend at all, it appeared to act in the opposite direction, towards a decrease in carcass fat.     

The nutritional value of algae for poultry. dried chlorella in broiler diets 1

1. The nutritional value of a sample of algae meal, mainly Chlorella, was assessed in two chick and two broiler trials. The algae were drum‐dried after harvesting from sewage ponds by centrifugation.

2. Diets formulated by linear programming contained between 60 and 150 g algae meal/kg by substituting algae meal and sorghum for fish meal, soyabean meal and maize in a control diet.

3. The effects of the dietary algae meal ranged from nil to a significant depression of growth rate and food utilisation. In certain cases growth retardation was associated with depressed food consumption.

4. The metabolisable energy concentration of the algae meal was estimated to be 11–62 MJ/kg and the nitrogen absorption coefficient 0.81.     

Evaluation of methanol‐grown bacteria and hydrocarbon‐grown yeast as sources of protein for poultry: Performance of broilers during the finishing period

1. Three trials were carried out with male broilers during the 5‐ to 8‐week period, for the evaluation of two types of single‐cell protein (SCP) in practical‐type broiler finisher diets. The SCP tested were: Pruteen, produced from methanol‐utilising bacteria, and a Lavera‐type yeast which utilises the normal paraffins of heavy gas oil.

2. The inclusion of 90 to 100 g of either type of SCP/kg of the diet caused a 2 to 3% reduction in weight gain, a 3 to 5% decrease in food consumption, and up to a 2% improvement in food utilisation. The reduced growth rate could be fully explained by the decrease in food intake, with essentially no effect on food : gain ratio.

3 In diets containing Pruteen, arginine was second limiting after the sulphur amino acids.

4 An odd‐numbered fatty acid (17 carbons, unsaturation unknown) of Pruteen was not found in the carcass lipids of broilers fed on a diet containing 120 g Pruteen/kg.     

Layout proposal for a microtitre plate to be used in routine antimicrobial susceptibility testing of bacteria from infections of dogs and cats

The determination of minimum inhibitory concentrations by broth microdilution is recommended as method of choice for susceptibility testing of veterinary bacterial pathogens. Accordingly, broth microdilution is used in veterinary routine diagnostic laboratories at a progressive rate. To reduce the costs of susceptibility testing, it is reasonable to develop widely accepted uniform microtitre plate layouts that are produced in large quantities. Such microtitre plate layouts have already been developed and published for the susceptibility testing of pathogens from food-producing animals. However, a microtitre plate layout, especially designed for the testing of bacteria from dogs and cats, should be available, too. The choice of the antimicrobial agents or combinations of antimicrobial agents to be included in a suitable layout should be based on the following criteria: (1) the approval and availability of an antimicrobial agent or combination of agents, (2) known cross-resistances, and (3) availability of approved clinical breakpoints. The latter point is of particular importance for the choice of the numbers of concentrations per antimicrobial agent tested and the range of test concentrations. Taking into account these aspects, a science-based layout proposal for microtitre plates, which are suitable for routine testing of bacteria from dogs and cats, is presented and discussed.     

The replacement of some of the soybean meal by the first limiting amino acids in practical broiler diets. I. The value of special supplementation of chick diets with methionine and lysine.

1. Three trials were carried out in order to determine the amount by which dietary protein concentration can be reduced while maintaining the dietary concentrations of the first two limiting amino acids, methionine and lysine. 2. In all trials growth rate and food utilisation declined as the protein concentration of a well-balanced standard chick diet was lowered by replacing soybean meal with sorghum grain (milo), but this trend could be partly or completely prevented when methionine or methionine and lysine levels were restored. 3. Addition of 0-06 to 0-07% methionine, above that considered to be normal, is sufficient to replace approximately 0.9% soybean protein. 4. In diets containing approximately 3 percentage units less soybean protein than required, a supplementation of about 0.15% each of methionine and lysine can replace nearly 2-0% soybean protein, but cannot bring about chick performance equal to that obtained on the control ration, indicating an insufficiency of a third, or third and fourth, limiting amino acid in such low-protein diets.