A comparison of continuous grazing systems for milk production

In two experiments conducted with Ayrshire dairy cows in 1974 and 1975 on swards of S23 perennial ryegrass, four systems of continuous grazing were investigated. The leys received 345 and 370 kg ha^-1 fertilizer nitrogen in 1974 and 1975 respectively and were stocked at the rate of five cows per ha. In 1974, a comparison was made between two systems which either integrated silage making with, or separated it from, the continuous grazing. The provision of a silage aftermath in late July increased milk yield after that time, but had no significant effect on milk yield over the 19-week experimental period. In 1975, a comparison between weekly and monthly applications of fertilizer N showed no significant differences between milk yields in a 20-week period. The feeding of supplementary concentrates from late July onwards significantly increased milk yield. The treatments in both years had only small and mainly non-significant effects on milk composition. On average, excluding the concentrate treatment, the annual output of milk was 10,800 kg ha^-1 using spring-calved cows.     

Studies on Herpesvirus scophthalmi infection of turbot Scophthalmus maximus (L.): Histopathological observations

Abstract. The histological features of the disease caused by infection of turbot by Herpesvirus scophthalmi are described. Infection of epidermal cells of skin and gill resulted in the formation of giant cells showing a variety of nuclear and cytoplasmic changes associated with the replication of the virus. The effects of the condition together with possible control measures are discussed.     

Conservation assessment of British limestone pavements based on floristic criteria

The total British area of limestone pavement is very small, yet this scarce resource is being destroyed to supply decorative stone. Its scientific interest is both geological and botanical. Exploiting an exhaustive survey, a weighted index was developed for assessing the conservation value of limestone pavements based on their deep grike floras. Using weighted indices, 27 sites in Cumbria, Gwynedd, Lancashire, North Yorkshire and Skye were identified as important for the conservation of limestone pavement floras.     

Nature conservation in Spain: A brief account

The history of nature conservation in Spain is reviewed with reference to public attitudes past, present and future. The eight National Parks are listed and described in terns of their location, date of foundation, extension and main historical, floristic and faunistic characteristics.The various other types of reserve and their aims and functions are alluded to and the significance of the role played by ICONA (National Institute for the Conservation of Nature) through the declaration and administration of these vast areas is stressed.Ample comment is made on the deficiency of past and current legislation and hope is expressed in connection with the May 1975 Law for the Creation and Conservation of Protected Natural Spaces.     

Thermal and spectrophotometric analysis of some fungal melanins and soil humic compounds

Seven types of fungal melanins were compared with humic compounds from chernozem and podzol soils and with commercial humic acid. The results indicate some similarities but also distinct differences between the melanins and humic substances in spectral characteristics in the UV and visible regions and in their resistance to thermal degradation.     

The distribution of nitrogen in some highly organic tropical volcanic soils

The qualitative and quantitative distribution of N-compounds in 10 tropical soils, and in a number of humic materials extracted from representative samples thereof, was determined after 6 N HCl hydrolysis.Eighty to 98% of the total N in the soils and humic materials was hydrolysable by 6n HCl. Slightly less than one half the hydrolysable N in the soils and humic fractions consisted of amino acids. Well-drained soils and fulvic acids extracted from them contained unusually high concentrations of the acidic amino acids, aspartic and glutamic acids. Between 80 and 95% of the amino acids in the soils was accounted for in the humic materials + NaOH-insoluble organic residues. NH⁺₄-N released by acid hydrolysis was generally higher for the soil samples than for the humic materials. Amino sugar-N constituted relatively small proportions of the total N in the soils and humic fractions.Our data suggest that large quantities of amorphous allophanic materials coupled with relatively high enzymic activity are responsible for the observed accumulation of acidic amino acids in the well-drained tropical volcanic soils.     

Volatilization of sulfur from unamended and sulfate-treated soils

Volatilization of sulfur from unamended and sulfate-treated soils was studied by sensitive gas chromatographic techniques using a flame photometric detector fitted with a sulfur filter. The soils employed were surface samples of 25 Iowa soils selected to obtain a wide range in properties. No release of volatile sulfur compounds was detected when 11 of these soils were incubated under aerobic or waterlogged conditions before or after treatment with sulfate (400 μg sulfate S/g soil). Fourteen soils released volatile sulfur compounds when incubated under waterlogged conditions before and after addition of sulfate, but only 4 of these soils released volatile sulfur compounds when incubated under aerobic conditions. Where volatilization of sulfur was observed, the volatile sulfur detected was identified as dimethyl sulfide or as dimethyl sulfide associated with smaller amounts of carbonyl sulfide, carbon disulfide, methyl mercaptan, and (or) dimethyl disulfide. No trace of hydrogen sulfide was detected. Where release of volatile sulfur was observed, the amount of sulfur volatilized at 30°C in 60 days under aerobic or waterlogged conditions was very small and did not account for more than 0–05% of the sulfur in the unamended or sulfate-treated soils studied. It is concluded that gaseous loss of sulfur from unamended or sulfate-treated soils is insignificant under conditions likely to be encountered in the field.     

Substances interfering with the gas-liquid chromatographic determination of T-2 mycotoxin.

Two substances interfering with the gas-liquid chromatographic (GLC) detection of T-2 mycotoxin were identified as 1-glyceryl-monooleate and 1-glycerylmonolinoleate. These monoglycerides are natural products formed by species of Fusarium growing on cereal grains and are also additives contained in liquid vegetable and animal fats added to the feed mixture. The monoglycerides can be removed from the analytical sample by resolution by thin layer chromatography prior to separation by GLC. Trimethylsilyl ether derivatives of the monoglycerides and T-2 toxin have almost identical retention times on 3% OV-1 columns, whereas the trifluoroacetyl and pentafluoropropionyl derivatives give baseline separation on the same column. The monoglycerides can be misidentified as the T-2 toxin in analyses involbing GLC.