Voluntary feed intake and growth performance of slow-growing pigs fed on increasing levels of ensiled potato hash meal.

The objective of the study was to determine voluntary feed intake and growth performance of Windsnyer pigs fed on increasing levels of potato hash silage meal. Thirty-six growing Windsnyer pigs (19 kg ± 5.59) (mean ± standard deviation (SD)) were individually and randomly assigned to six experimental diets containing 0, 80, 160, 240, 320 and 400 g/kg DM of potato hash silage. Diets containing the potato hash silage were formulated using diet dilution method from 0 g/kg and 400 g/kg. Six pigs were fed on each diet ad libitum for 6 weeks. Average daily feed intake (ADFI), average daily gain (ADG), gain to feed (G/F) ratio, scaled feed intake (SFI) and scaled average daily gain (SADG) were measured weekly. Increasing levels of potato hash silage caused a decrease (P < 0.05) in ADG, G/F ratio and SADG. The ADFI interacted significantly (P < 0.05) with the inclusion level of potato hash silage and week of feeding. Pigs fed on 240 g/kg potato hash silage had greater ADFI in the second, third and fourth week of feeding. There was a quadratic increase (P < 0.05) in ADFI. There was a linear decrease (P < 0.05) in ADG and G/F ratio and SADG as the potato hash silage level increased. Using piecewise regression, potato hash silage can be included up to 240 g/kg DM in Windsnyer pigs without undermining growth performance.

Localization of DNA phosphorus in Tipula iridescent virus by oxygen plasma microincineration. I. Electron microscopy of ash structures.

Tipula iridescent virus (TIV) is a relatively large particle containing about 15% DNA. As shown elsewhere by X-ray microanalysis (Thomas RS, Corlett M: J Histochem Cytochem 29:394, 1981), low-temperature oxygen plasma microincineration of the virus produces a stable phosphorus oxide ash representing this DNA nearly quantitatively. Transmission electron microscopy (TEM) of entire particles after plasma incineration shows the ash confined to the viral cores, confirming the previously known general location of the nucleic acid. Examination of ultrathin-sectioned virus crystals after plasma etching or ashing shows, on a still finer scale, that the DNA is probably confined to a shell structure within the core. A fine trace of ash from the capsid, seen in some preparations, may represent a phospholipid internal membrane known to be present. The possibilities of ash pattern artifacts are discussed. Heating experiments show that the ash patterns (and native virus particles) evaporate completely at high temperature, consistent with their presumed polyphosphoric acid composition. A heat-stable ash could be formed, however, when the viral DNA became accidentally stained with iron from the steel TEM grids used--a noteworthy artifact. The present work suggests some future possibilities of the plasma microincineration technique. In particular, the ability to see directly the fine distribution of mineral concentrations in ash patterns with the full resolution of TEM should be a powerful adjunct to increase effectively the sensitivity and resolution of X-ray microanalysis of mineral constituents in biological specimens.

Localization of DNA phosphorus in Tipula iridescent virus by oxygen plasma microincineration. II. Electron probe X-ray microanalysis of ash constituents.

Microincinerated, 1-micrometer sections of Tipula iridescent virus (TIV) crystals were analyzed quantitatively with a wave-length-dispersive electron microprobe to determine the chemical composition of high-resolution ash patterns previously obtained from ultrathin sections of the same specimen (Thomas RS: J Histochem Cytochem 29:379, 1981). Parallel analyses were performed on intact sections. In some cases, the same section and probe tracks were analyzed both before and after ashing. The principal elemental constituent of the ash was phosphorus, representing nearly all of the phosphorus found in the unashed sections. This confirmed the likely DNA origin of most of the ash. Other elements--sulfur, calcium, sodium, and perhaps carbon and nitrogen--found in relatively small concentrations in the ash, were partly due to either to incomplete ashing or to a particulate contaminant. Similar plasma ashing and analyses of sectioned model preparations of polymethacrylate containing dissolved triphenyl phosphate confirmed that phosphorus, by itself, could be retained as a stable ash. Analyses of polymethacrylate containing aluminum as well as phosphorus disclosed an unexpected artifact--aluminum inhibited the plasma ashing. These results suggested that the wavelength-dispersive probe, able to analyze for carbon and nitrogen as well as mineral elements, should be a generally useful tool in analyzing plasma microincineration phenomena, where macroscopic results do not apply. Relatively high beam intensity used throughout the probe analyses caused obvious damage to intact sections, particularly when they were mounted on thin-film supports. In contrast, the ash appeared quite stable. This suggested that plasma ashing of biological sections, converting them into mineralogical specimens, may be generally useful in probe analyses of mineral constituents, permitting greater sensitivity via higher beam currents, higher mineral concentrations, and lower backgrounds.

X-ray microanalysis of epon sections after oxygen plasma microincineration.

Dark-gold sections of osmium tetroxide-fixed, Epon-embedded brown adipose tissue before and after low-temperature oxygen plasma microincineration were examined using a high-resolution scanning transmission electron microscope and an energy-dispersive X-ray spectrometer. Microincineration produced ash patterns which were free of organic matrix, chlorine (from the Epon) and probably osmium (from the fixative). X-ray sensitivity was improved by a factor of 2-4 owing to decreased background, and sulphur, calcium and probably phosphorus were detected in the ash. Fidelity of the ash patterns permitted microanalytical spatial resolution of 0.1 micrometer or better. Oxygen plasma microincineration is thus shown to offer advantages for high resolution X-ray microanalysis of conventionally sectioned biological material. Its future application to shock-frozen, frozen-dried, unstained sections is indicated.