ALBERT

Description: The stability of a uniformly rotating and infinitely conducting jet with twisted magnetic field is discussed. The dispersion relation is obtained for the non-axisymmetric perturbations; this involves a complex and implicit function of the growth rate. The complex growth rate implies that instability develops as an overstability. The effect of axial current is destabilizing for both the instabilities m = 0 and m = 1 discussed here. The effect of rotation on the stability of the jet is as follows: (a) for the m = 0 mode, rotation always has a destabilizing effect; (b) for the m = 1 mode, rotation has a stabilizing effect for very long-wave perturbations, but for short-wave perturbations it destabilizes the jet. In particular there exists a disturbance of a particular wavelength which is unaffected by the rotation of the jet. © 1965, Cambridge University Press. All rights reserved.

Description: This study was carried out from September 1998 to August 1999, by conducting three experiments, one each in the monsoon, winter and summer seasons. The forage availability and botanical composition of native range were obtained. Five 3–4-year-old Kutchi males, weighing 50–55 kg, were used to determine total faecal output, and were observed to allow the diet selected to be sampled by the hand plucking method. Dry matter (DM) yield of range was highest during winter and lowest during monsoon, annual mean being 1611 kg DM/ha. Contribution of shrub foliage to total forage yield in monsoon, winter and summer was 3·81, 1·64 and 9·98%, respectively. Crude protein (CP) content (g/kg DM) of ground vegetation declined from 99 in monsoon to 72 in winter and 66 in summer, while that of top foliage remained similar in all the seasons (mean CP 142 g/kg). Goats consumed a diet of almost the same CP content (mean CP 137 g/kg) in all the seasons. Goats consumed 64·0, 54·0 and 55·9 g DM/kg W0·75/day, in monsoon, winter and summer (annual mean 58·0 g DM/kg W0·75 /day). DM and CP digestibility coefficients were higher in monsoon and summer (mean DM 0·595; CP 0·533) and decreased (P 〈 0·05) in winter (DM 0·485, CP 0·424). Neutral detergent fibre (NDF) and acid detergent fibre (ADF) digestibility coefficients were highest in monsoon (NDF 0·542; ADF 0·446), and declined (P 〈 0·05) to 0·340 and 0·266 in winter and 0·415 and 0·326 in summer. Digestible crude protein (DCP) intake was almost similar in monsoon and summer (mean 4·6 g/kg W0·75 /day) and declined (P 〈 0·05) in winter (3·1 g/kg W0·75 /day), while metabolizable energy (ME) intake was higher in monsoon (0·90 MJ/kg W0·75 /day) and declined (P 〈 0·05) to 0·78 and 0·80 MJ/kg W0·75 /day, in winter and summer, respectively. Average body weight of goats in monsoon, winter and summer was 54·0, 54·6 and 56·5 kg, respectively (annual mean 55·0 kg). It is concluded that goats grazing on a semi-arid rangeland meet their DCP and ME requirement throughout the year.

Description: Few methods exist for estimating quantitatively the diet composition of free-ranging herbivores. The current study examined whether long-chain fatty alcohols (alcohols) or long-chain fatty acids (acids) could be used along with n-alkanes to allow reliable diet composition estimates to be made in herbivores consuming complex diets. Twelve Scottish Blackface wether sheep housed in metabolism crates were fed four different mixtures of three plant species (three animals per mixture) for a seven-period experiment. Concentrations of cuticular wax n-alkanes, alcohols and acids were estimated in samples of individual plant species, and the faeces from animals that consumed mixtures of these species. These concentrations were then used to calculate the dietary proportions of each species by a least-squares optimization procedure. To explore the differences between the estimation methods (individual markers and their combinations), the mean squares of errors (EMS) between the actual and predicted proportions of plant species were calculated.In three out of the four mixtures, alcohols had the lowest discrepancies (lowest EMS values), followed by n-alkanes and then acids. Acids yielded the lowest discrepancy in one mixture and the highest in the others.It is concluded that, for this particular set of mixtures, alcohols had great potential to estimate composition of complex diets. However, the estimation using acids was less good and n-alkanes were of intermediate potential. Estimation from the combination of the three marker classes was always better than using the poorest individual marker.

Description: A study of the physiological responses and energy expenditure of goats was carried out from June 1999 to May 2000 by conducting two experiments: one on bucks maintained on stall feeding in autumn 1999 (Expt 1) followed by year-round grazing on native ranges over three seasons: monsoon, winter and summer (Expt 2). Physiological responses and energy expenditure (EE) measurements of housed and grazing goats were recorded at 06.00 h and 14.00 h for 5 consecutive days in each season. Goats were fixed with a face mask and meteorological balloon for collection of expired air and measurement of EE. Respiration rate (RR) at 06.00 h was similar in all seasons (14 respiration/min) except in the monsoon, where a significantly (P

Description: Previous investigations have shown that the long-chain fatty alcohols and long-chain fatty acids of plant waxes have potential as diet composition markers. This study was conducted to measure faecal recoveries of long-chain fatty alcohols (C20–C30) and long-chain fatty acids (C20–C32) in sheep fed mixed diets. Methodology for quantitative analysis of these compounds in feed and faeces is also presented. The method was an extension of the original n-alkane method of Mayes et al. (1986) in which separate hydrocarbon (n-alkanes, n-alkenes and branched-chain alkanes), alcohol (free+esterified) and acid (free+esterified) fractions could be obtained from a single sample. A fraction containing alcohols and sterols was eluted from the silica gel column after removal of the hydrocarbons. Sterols were removed from alcohols using aminopropyl solid-phase extraction columns. Alcohols were converted to their trimethylsilyl (TMS) ethers and run on a gas chromatograph (GC). Acids were extracted from the aqueous phase of saponification products after removal of hydrocarbons, alcohols and sterols, purified through silica gel columns and were converted into their methyl esters (FAMES) prior to analysis on a GC. Tests were carried out to evaluate the reproducibility of the results obtained from the analytical method developed for quantifying alcohols and acids. Twelve sheep, in metabolism crates, were offered (0·8 kg DM/animal/day) four different mixtures of hill grass (Agrostis capillaris), birch (Betula pendula) leaves and current season's growth of heather (Calluna vulgaris) and bilberry (Vaccinium myrtillus) for 17 days. Total daily faeces and feed refusals collections were carried out over the last 7 days. Faeces collections were bulked for each animal. Representative samples of feed, refusals and faeces were analysed for alcohols and acids using the described method. Faecal recoveries of alcohols and acids were calculated from the ratio of output and input of each marker. The results showed high, though incomplete, faecal recoveries for both alcohols and acids. Alcohols had consistently higher faecal recoveries compared with acids. Mean (±S.E.) faecal recovery values for alcohols C20, C22, C24, C26, C28 and C30 were 0·58±0·04, 0·67±0·01, 0·72±0·008, 0·80±0·007, 0·94±0·005 and 1·01±0·02, respectively, whereas those of acids C20, C22, C24, C26, C28, C30and C32 were 0·47±0·02, 0·57±0·02, 0·61±0·02, 0·77±0·017, 0·84±0·01, 0·79±0·015 and 0·84±0·013, respectively. Increasing chain-length had a significant effect (P0·05) on the recoveries of alcohols and acids in faeces.

Description: SUMMARYFifty-two genotypes of rice bean (Vigna umbellata Thunb. (Ohwi and Ohashi)), an under-cultivated crop, were evaluated in the rainy (kharif) seasons of 2001, 2002 and 2003 in the North Eastern Hill Region, India to select suitable genotypes for cultivation in the North Eastern Hill region and to identify promising parents for hybridization programmes. The germplasm studied comprised 44 Indian and eight foreign genotypes. A wide range of variability was observed for eight characters studied (plant height, number of branches/plant, stem thickness, pod length, number of seeds/pod, 100-seed weight, pod weight/plant and seed yield/plant). Number of days to mid-flowering and number of days to maturity showed little variation. High heritability (0·58) and high genetic advance (0·53) were observed for 100-seed weight, high heritability (0·93) and moderate genetic advance (0·37) for seed yield/plant, and high heritability (0·60) and low genetic advance (0·13) for number of days to mid-flowering. Since the main aim in rice bean breeding is to develop high yielding, early maturing genotypes with low plants, selection was based mainly on the mean performance of these three traits over the 3 years, as well as their stability. One of the genotypes, RBL 1, was very high yielding, although the yield was not stable across years. Another genotype, RBS 24, was very early maturing and had very short plants compared with the other genotypes studied. These two, along with several other genotypes selected, may be promising for a hybridization programme aiming to develop dwarf, early maturing genotypes with high yield. The best yielding genotypes, namely RBL 1, RCRB1-3 and IC 187911, may be recommended for cultivation in the shifting cultivation areas (Jhum) regions of North Eastern India.