Polyunsaturated fatty acids (PUFA) of lean meat from domesticated and wild ruminants (cattle, sheep, goat, sambar deer and buffalo) and non-ruminants (pig, horse and kangaroo) have been examined by capillary gas-liquid chromatography. Ten different PUFA were found in all specimens with linoleic acid accounting for at least 50% of the total, and arachidonic and linolenic acids being the next most abundant. The total PUFA content for the ruminants ranged from 9 % in beef to 31 % in sambar deer and for the non-ruminants from 25 % in pig to 43 % in horse. In all species the meat phospholipids (PL) were rich in PUFA (range 2 4 4 6 % of PL fatty acids), whereas the triglycerides were relatively more saturated (PUFA content range 2-17 %). Overall, horse and kangaroo meat had the Combination of lowest fat and highest PUFA content, whilst beef and sheep had the highest fat and lowest PUFA content. These results indicate that significant reductions in total fat intake and increases in the proportion of polyunsaturated fat in the diet could be achieved without necessarily requiring a diet low in meat.
Increases in soil acidification have led to large increases in the application of aglime to Australian agricultural soils. The addition of aglime has the potential to increase greenhouse gas (GHG) emissions due to the release of CO2 during the chemical dissolution of aglime and due to pH-induced changes to soil biological processes. Currently, Australia’s GHG accounting system assumes that all the carbon contained in aglime is released to the atmosphere during dissolution in accordance with the Tier 1 methodology of the IPCC. However, a recent approach by TO West and AC McBride has questioned this assumption, hypothesising that a proportion of the carbon from riverine-transported aglime may be sequestered in seawater. In addition, there is presently no capacity within Australia’s carbon accounting system to quantify changes to GHG emissions from lime-induced changes to soil biological processes. Therefore, the primary objective of this review was to examine the chemical and biological processes occurring during the application of aglime and the subsequent fluxes in CO2, N2O, and CH4 from soil, with particular reference to the Australian environment. Estimates for CO2 emissions from aglime application in Australia using the contrasting methodologies of the IPCC and West and McBride were compared. Using the methodology of the IPCC it was determined that from the aglime applied in Australia in 2002, 0.995 Tg of CO2 would have been emitted, whereas this figure was reduced to 0.659–0.860 Tg of CO2 using the methodology of West and McBride. However, the accuracy of these estimates is currently limited by poor understanding of the manner in which aglime moves within the Australian landscapes. In addition, there are only a very small number of Australian studies that have examined the effect of aglime on GHG emissions due to changes in soil biological processes, limiting the ability of Australian modellers to accurately incorporate these processes within the carbon accounting system.
It has been suggested that the cat is unable to convert dietary linoleic acid to arachidonic acid (Rivers et al. 1975;Hassam et al. 1977). Studies by Sinclair et al. (1979) demonstrated that the cat has a deficiency in the synthesis of
Several sampling methods were investigated for the quantification of organic anions in the rhizosphere of Al-tolerant (ET8) and Al-sensitive (ES8) wheat plants in soil systems. Controlled environment studies used anion exchange membranes to collect rhizosphere organic anions (from root tips and mature regions of nodal roots) from ET8 and ES8 plants at the 6-leaf stage in a glasshouse environment. Using the anion exchange membranes, a selection of organic anions were detected on the tips and mature regions of roots, with ET8 and ES8 having similar rhizosphere organic anion profiles. The field experiment used 2 established methods of organic anion collection: rhizosphere soil and root washings. The ET8 and ES8 wheat lines had similar levels of organic anions, including malate, in the rhizosphere (using soil shaken from roots and root washings) at 3 sampling times (4 and 6 leaves, and flowering). The rhizosphere organic anions differed significantly from the bulk soil, with the concentration and range of organic anions in the rhizosphere decreasing towards flowering, presumably due to physiological changes in plant and root growth. This study used several techniques to investigate organic anion exudation by roots, with organic anions detected using all techniques. However, technical limitations of these techniques were recognised: (i) the lack of simultaneous exposure of root tips to both the anion exchange membrane and the chemical stimulant, e.g. Al 3+ ; and (ii) the inability to derive the origin of organic anions measured in rhizosphere soil and root washings. The challenge for future soil-based organic anion research is to identify the dominant stress that has triggered an exudation response (i.e. Al toxicity, P deficiency), and to clearly differentiate between plant-and microbial-derived contributions to exudation.
Summary. A long-term experiment in north-eastern Victoria has been regularly monitored for wheat yield responses to a range of lime and fertiliser treatments, and the soil sampled for acidity attributes. Substantial grain yield increases have been consistently obtained over a period of 12 years with a single lime application. Lime applied at 2.5 t/ha in 1980 was still providing yield increases of 24% with an acid-tolerant wheat (Matong, 1992 season) and 79% with an acid-sensitive wheat (Oxley, 1993 season) relative to no lime treatment. The 2 wheat cultivars responded differently to phosphorus fertiliser, with the acid-sensitive wheat less responsive to phosphorus fertiliser in the absence of lime. The use of a regular lime application applied as a fertiliser (125 kg lime/ha) with the wheat seed gave only a small grain yield increase (8% Matong, 16% Oxley), despite 1 t/ha of lime applied over the 12-year period. Liming the soil at a rate of 2.5 t/ha (1980) initially raised the soil pH by about 1.0 unit and removed most soluble aluminium (0–10 cm). However, after 12 years of crop–pasture rotation after the initial 2.5 t lime/ha treatment the soil pH had declined by 0.7 of a pH unit and exchangeable aluminium was substantially increased, almost to levels prior to the initial application of lime. Given the continued yield responsiveness obtained following the initial application of lime, this practice, rather than regular applications of small amounts of lime, is recommended for wheat production on strongly acidic (pHw < 5.5) soils in south-eastern Australia.
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