Differences In Nitrogen Content Research Articles

Studies on the nutritive value of the diet selected by grazing sheep. I. Differences in composition between herbage consumed and material collected from oesophageal fistulae

Freshly-cut forages and lucerne chaff were given to penned sheep fistulated at the oesophagus. The feed given and the samples obtained through the fistula were analysed for in vitro digestibility, nitrogen, ash, phosphorus, sodium, potassium and calcium. Organic matter digestibility was predicted from the in vitro determination.Three regression equations were calculated relating predicted organic matter digestibility of the feed to the digestibility of the extrusa sample. The most precise of these equations had a residual standard deviation of ±3·4 units.The relationship between the nitrogen contents of the feed and sample was calculated. The equation did not pass through the origin but the differences in nitrogen content between feed and extrusa were small over the range 4·69 to 1·28% N included in this study. The nitrogen and calcium contents of the feed could be estimated from the sample with errors of ±7·5 and 9% respectively. The sodium, potassium and ash contents of the diet could not be reliably estimated from an oesophageal sample.

DIFFERENCES IN NITROGEN CONTENT IN EXTRACTS OF CHILLED AND NON-CHILLED TISSUES

In an attempt to elucidate the increase of growth promotion of tissue cultures by extracts obtained from tissues chilled before extraction, determinations of nitrogen content were made on (a) fresh, and chilled chick embryos, (b) extracts prepared from fresh and chilled chick embryos, (c) fresh and chilled human placenta, (d) extracts prepared from fresh and chilled human placenta.There was no difference in dry weight, nitrogen content, phosphorus content, and nitrogen: phosphorus ratio between chilled and fresh chick embryos and chilled and fresh human placenta. There was, however, a significant difference in the nitrogen content of the extracts prepared from fresh and from chilled tissues, It is suggested that chilling of tissues for 7 days at + 4 °C. prior to extraction may render the cells more easily destructible during extraction, and thus supply a better yield of nutritive substances.

DIFFERENCES IN NITROGEN CONTENT IN EXTRACTS OF CHILLED AND NON-CHILLED TISSUES

In an attempt to elucidate the increase of growth promotion of tissue cultures by extracts obtained from tissues chilled before extraction, determinations of nitrogen content were made on (a) fresh, and chilled chick embryos, (b) extracts prepared from fresh and chilled chick embryos, (c) fresh and chilled human placenta, (d) extracts prepared from fresh and chilled human placenta.There was no difference in dry weight, nitrogen content, phosphorus content, and nitrogen: phosphorus ratio between chilled and fresh chick embryos and chilled and fresh human placenta. There was, however, a significant difference in the nitrogen content of the extracts prepared from fresh and from chilled tissues, It is suggested that chilling of tissues for 7 days at + 4 °C. prior to extraction may render the cells more easily destructible during extraction, and thus supply a better yield of nutritive substances.

THE NON-PROTEIN NATURE OF A FRACTION OF SOIL ORGANIC NITROGEN

It is shown that not all the nitrogen in organic soils is determinable by the Kjeldahl method. In every sample tested the Dumas method gave a considerably higher percentage of nitrogen.The differences in nitrogen content, as shown by the two methods, vary from 6.4 to 29.6%, hence it is believed that an appreciable fraction of the soil organic nitrogen may be of non-protein nature.