Atomic absorption spectroscopic determination of lead extracted from acid-solubilized tissues.

A method is presented for determining lead in a variety of tissues. Lyophilized samples are solubilized with nitric acid at room temperature in glass screw-cap culture tubes. Following neutralization with sodium hydroxide and sodium bicarbonate, the lead is extracted into methyl isobutyl ketone as the pyrrolidine dithiocarbamate complex and analyzed by flame atomic absorption spectrophotometry. Brain, heart, liver, lung, and spleen gave recoveries ranging from 92 to 102% with standard deviations of less than 8%. Aorta, kidney, and rib were unsuitable for analysis by this method. A large number of samples can be analyzed without specialized equipment or intricate experimental steps. The detection limit is 35 ng/g tissue (wet weight) and sensitivity is approximately 140 ng/g tissue (wet weight).     

Evaluation of techniques for quantitative detection of Phytophthora cinnamomi

Three baiting techniques and a sieving technique were evaluated for the quantitative detection zof Phytophthora cinnamomi Rands. Baiting with seedlings of Lupinus angustifolius L. (blue lupins), cotyledons of Eucalyptus sieberi F. Muell. and pear fruits cv. Packham's Triumph, detected one chlamydospore introduced into 50 g of either sand or soil. Sieving detected one chlamydospore in 50 g sand and also in 5 g soil. In naturally-infested soil, diluted with a similar non-infested soil, P. cinnamomi was detected at dilutions of $\text{1}\text{8}$ and $\text{1}\text{128}$ by the sieving and the baiting techniques, respectively. In general, pears were the most satisfactory bait for the detection and isolation of P. cinnamomi. The potential of baiting techniques for estimating numbers of propagules of P. cinnamomi in naturally-infested soil is discussed.     

Automated method for the determination of niacin and niacinamide in cereal products: collaborative study.

In a collaborative study, an automated method for the determination of niacin and niacinamide in cereal products was compared with the official final action microbiological (43.121-43.125) and chemical (43.044-43.046) methods. Ten samples of cereal products, including enriched flour, yeast-leavened baked products, fortified breakfast cereals, and baked pet food products, were submitted to 14 laboratories. Nine laboratories reported values by the automated method, 6 reported values by the microbiological method, and 7 reported values by the chemical method. The results from the microbiological method were not subjected to analysis of variance because of the unusually large between-laboratory variation. The between-laboratory coefficients of variation for the automated and chemical methods were 10.90 and 10.18%, on the basis of results from 7 and 4 laboratories, respectively. There was no significant (p greater than 0.05) difference between methods when results from the 4 laboratories who used both methods were compared. The automated chemical method has been adopted as official first action.     

Estimating the abundance and diversity of butterflies

Concern about the apparent decline in butterfly populations has led to projects designed to obtain quantitative information on their abundance and diversity. Three methods of sampling communities of butterflies are suggested, and the use of a diversity index, β, is recommended. This index gives an estimate of the probability that an individual sampled at random from a community will be different from the previous individual sampled. Change and stability in diversity can be used as a guide for conservation and management programmes.     

THE EFFECT OF INCLUDING DRIED GRASS IN THE SUPPLEMENT GIVEN TO LACTATING COWS AT PASTURE

An investigation into the effect of including dried grass in the supplement given to dairy cows at pasture is reported. Supplements containing 0, 50 and 100% dried grass were used in the investigation which was carried out in two parts. In the first part 12 high-yielding cows with unrestricted access to pasture were used in an experiment with a change over design to assess the effects of feeding 5 kg/day of each supplement on milk yield and composition. In the second part 8 steers, housed in stalls and given cut herbage from the same sward as that grazed hy the cows, were used in a change over experiment to assess the effects of the three supplements on herhage and total DM intake. No significant differences in milk yield between supplements were ohtained, the mean yields being 23·9, 24·5 and 23·9 kg/day for the supplements containing 0, 50 and 100% dried grass, respectively. Milk composition was also not significantly affected by including dried grass in the supplement. In the indoor feeding trial using the steers, the addition of 3·5 kg DM from the supplement resulted in an increase in total DM intake of only 1·3 kg/day. There was no significant difference hetween supplements on herbage and total DM intake.     

A NOTE ON THE ZERO-GRAZING OF BEEF CATTLE

Groups of 8 steers weighing 300–400 kg (660–880 Ib) were rotationally grazed on a ryegrass-dominant pasture for 115 days. The systems compared were zero grazing (Z), field grazing conducted at the same stocking rate (FC), and field grazing conducted at a stocking rate varied with the intention of giving the same liveweight gain per uiimal as zero grazing (FV). Mean daily liveweight gains were: Z, 0.98; FC, 0.78; FV, 0.90 kg/animal (2.2, 1.7 and 20 Ib/animal), and liveweight gains/unit area were in the ratio 100:78:85. Organic-matter intake, measured on four occasions, was, on average, Z, 6.54; FC, 6.18; FV, 687 kg/head daily (14.4, 13.6 and 15.1Ib). From these results it appears that a comparison of zero grazing and field grazing made at the same stocking rate is likely to underestimate the potential of field grazing for beef production from grass.     

Insektizide Nebel im Forstschutz

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