Feeding behaviour of yaks on spring, transitional, summer and winter pasture in the alpine region of the Qinghai-Tibetan plateau

Of the present estimated world population of 14.2 million yaks, approximately 13.3 million occur within Chinese territories (Food and Agriculture Organization of the United Nations, 2003). Although there is an extensive bibliography covering the species, few studies have been conducted in the area of foraging behaviour. The present study was conducted at pasture during the spring, transitional, summer and winter seasons to determine the daily temporal patterns of grazing and ruminating behaviour by yaks. During each study period, two 24 h recordings were undertaken with each of six mature dairy yaks. One study period was conducted on each of the transitional, summer and winter pastures, whereas, due to the considerable changes occurring in the morphology of the spring pasture, three separate studies were completed during March, April and May. During the second of these studies (April), the effect of level of concentrate supplementation on grazing and ruminating behaviour was also examined. Behaviour recordings were made using solid-state behaviour recorders. Short-term intake rates (IR, g min(-1)) were calculated by weighing yaks before and after approximately 1 h of grazing, retaining the faeces and urine excreted and applying a correction for insensible weight loss. Yaks spent less time grazing during the dry season (the early period on the spring pasture) compared with the later green swards (the later period on the spring pasture, the transitional pasture and the summer pasture) (P < 0.05). When the forage quality improved, but there was still insufficient mass (the later period on the spring pasture), the yaks extended their grazing time at the expense of other activities. During the early periods on the spring pasture, the short-term IR by yaks was up to 53 g DM min(-1), significantly higher than at other times (P < 0.05). The level of concentrate offered had little or no effect on grazing or ruminating time. The total eating time of the yaks offered 0.5 or 1.0 kg concentrate was 2.9 and 4.5 h day(-1) respectively, significantly lower than unsupplemented yaks (6.8 h) (P < 0.05). In general, yaks can regulate their foraging behaviour according to the changes of sward conditions in order to achieve optimal grazing strategies. (C) 2007 Published by Elsevier B.V.

Grazing behavior of lactating and non-lactating yaks in the summer season of the Qinghai-Tibetan plateau

The effect of the physiological states of lactating vs. non-lactating (dry) on grazing behavior and herbage intake by yaks was examined in the summer season in the Qinghai alpine area under continuous stocking management. Intake rates were estimated over periods of 1 h by weighing the animals before and after grazing, retaining the feces and urine excreted, and applying a correction for insensible weight loss (the 1-h weight changes of yaks when non-eating before or after the intake rate measurement). It is hypothesized that the lactating yaks should eat more and spend more time eating than nonlactating yaks, because they expend more energy. In our experiment, there were no differences in the effect of physiological state (lactating vs. dry) of yaks observed on the rate of insensible weight loss, intake rate, grazing jaw movement rate, bites per grazing jaw movement, or bite mass. The dry yaks tended to eat more and spend more time eating than lactating yaks, but not significantly so. Compared with the dry yaks, the lactating yaks had a significantly lower bite rate and bites per bolus.

Effects of salinity on food intake, growth, and survival of pufferfish (Fugu obscurus)

The food intake, growth, food conversion ratio and survival of yearling pufferfish, Fugu obscurus Abe, were investigated under different water salinity conditions over a 54-day period. Within the salinity regimes of 0 (freshwater), 8, 18, and 35parts per thousand, the food intake levels were 0.97%, 1.43%, 1.19% and 1.01%, respectively; food conversion ratios were 1.31, 1.93, 1.61 and 1.36, respectively; and specific growth rates were 0.41%, 1.15%, 0.84%, and 0.35%, respectively. The three data series were reduced with increasing salinity. However, the survival rates did not show the same tendencies, which were 80%, 100%, 100%, and 67%, respectively. There were significant differences among the treatments. In conclusion, the yearling pufferfish optimum culture salinity condition was about 8parts per thousand.

Kinetic Assessment of Measured Mass Flow Rates and Streamwise Pressure Distributions in Microchannel Gas Flows

Measured mass flow rates and streamwise pressure distributions of gas flowing through microchannels were reported by many researchers. Assessment of these data is crucial before they are used in the examination of slip models and numerical schemes, and in the design of microchannel elements in various MEMS devices. On the basis of kinetic solutions of the mass flow rates and pressure distributions in microchannel gas flows, the measured data available are properly normalized and then are compared with each other. The 69 normalized data of measured pressure distributions are in excellent agreement, and 67 of them are within 1 +/- 0.05. The normalized data of mass flow-rates ranging between 0.95 and 1 agree well with each other as the inlet Knudsen number Kn (i) < 0.02, but they scatter between 0.85 and 1.15 as Kn (i) > 0.02 with, to some extent, a very interesting bifurcation trend.

Surface morphology and properties of zirconia thin films prepared at different deposition rates

ZrO2 thin films were prepared on BK7 glass substrates by electron beam evaporation deposition method. The influence of deposition rate varying from 1.2 to 6.3 nm s(-1) on surface morphology and other properties of ZrO2 films were examined. With increasing deposition rate, the surface defect density increased. The decrease in half width at full maximum in X-ray diffraction pattern with deposition rate indicates an increase in crystal dimension with increasing deposition rate. Electron beam deposited ZrO2 films are known to be inhomogeneous. From the change of the peak transmittance value, it can be deduced that the inhomogeneity of ZrO2 films strengthened gradually with increasing deposition rate. The type of surface defects changed from nodules to craters when the deposition rate was high enough.

Characterization of LaF3 coatings prepared at different temperatures and rates

LaF3 thin films were prepared by thermal boat evaporation at different substrate temperatures and various deposition rates. X-ray diffraction (XRD), Lambda 900 spectrophotometer and X-ray photoelectron spectroscopy (XPS) were employed to study crystal structure, transmittance and chemical composition of the coatings, respectively. Laser-induce damage threshold (LIDT) was determined by a tripled Nd:YAG laser system with a pulse width of 8 ns. It is found that the crystal structure became more perfect and the refractive index increased gradually with the temperature rising. The LIDT was comparatively high at high temperature. In the other hand, the crystallization status also became better and the refractive index increased when the deposition rate enhanced at a low level. If the rate was super rapid, the crystallization worsened instead and the refractive index would lessen greatly. On the whole, the LIDT decreased with increasing rate. (C) 2007 Elsevier B.V. All rights reserved.

Effects of deposition rates on laser damage threshold of TiO2/SiO2 high reflectors

TiO2 single layers and TiO2/SiO2 high reflectors (HR) are prepared by electron beam evaporation at different TiO2 deposition rates. It is found that the changes of properties of TiO2 films with the increase of rate, such as the increase of refractive index and extinction coefficient and the decrease of physical thickness, lead to the spectrum shift and reflectivity bandwidth broadening of HR together with the increase of absorption and decrease of laser-induced damage threshold. The damages are found of different morphologies: a shallow pit to a seriously delaminated and deep crater, and the different amorphous-to-anatase-to-rutile phase transition processes detected by Raman study. The frequency shift of Raman vibration mode correlates with the strain in. film. Energy dispersive X-ray analysis reveals that impurities and non-stoichiometric defects are two absorption initiations resulting to the laser-induced transformation. (C) 2008 Elsevier B. V. All rights reserved.

DIFFERENT RATES OF MITOCHONDRIAL-DNA SEQUENCE EVOLUTION IN KIRK DIK-DIK (MADOQUA-KIRKII) POPULATIONS

We have investigated evolutionary rates of the mitochondrial genome among individuals of Madoqua kirkii using the relative rate test. Our results demonstrate that individuals of two chromosome races, East African cytotype A and Southwest African cytotype D, evolve about 2.3 times faster than East African cytotype B. Cytogenetic changes, DNA repair efficiency, mutagens, and more likely, hitherto unrecognized factors will account for the rate difference we have observed. Our results suggest additional caution when using molecular clocks in the estimation of divergence time, even within lineages of closely related taxa. Rate heterogeneity in microevolutionary timescales represents a potentially important aspect of basic evolutionary processes and may provide additional insights into factors which affect genome evolution. (C) 1995 Academic Press, Inc.

Transcription rates of yeast genes are influenced by the distribution of introns

A comparative analysis on the intron sequence oligonucleotide usages in two sets of yeast genes with higher and lower transcription frequencies, respectively, has shown that the intron sequence structures of the two sets of genes are different. There are more potential binding sites for transcription factors in the introns of the genes with high transcription frequencies. So it is speculated that introns regulate the transcription of genes. But more evidences are needed to favor this speculation. The detailed comparative analyses on the distribution ( length and position) of introns and exons in the two sets of gene sequences also show that there is an obvious boundary between the lengths of the two sets of introns. There is no boundary between the lengths of the two sets of exons, although the means of their lengths are of discrepancy. The situation of the gene lengths ( length of intron and exon) is similar to exon lengths. As far as the relative position, the introns in two sets of genes all have a bias toward the 5' ends of genes. But as the actual position is considered, more introns in high transcription genes have a tendency to be located toward the 5' ends of genes, some even located at 5'-UTR. These results suggest that the gene transcription rates are related to the length of intron, but not to the lengths of exons and genes sequences. The positions of introns may also influence the transcription rates. The transcriptional regulation of introns may be correlative with the transcriptional regulation of the upstream of genes, or be its continuous action.

Feeding rates affect heat shock protein levels in liver of larval white sturgeon (Acipenser transmontanus)

A two-week trial was conducted to study the effect of feeding rates on heat shock protein levels in larval white sturgeon. The larvae (30 day post hatch, 230 mg initial body weight) were fed a commercial feed (12.6% moisture, 49.5% crude protein. 20.7% Crude fat, and 8.6% ash) at 5, 15. or 25% body weight per clay (BW d(-1)). Liver heat shock proteins (Hsp) were measured before and after the larvae were subjected to a heat shock from 18 to 26 degrees C at 1 degrees C/15 min and maintained at 26 degrees C for 4 h thereafter. Before heat shock, larvae fed 5% BW d(-1) had significantly (P<0.05) lower final body weight, RNA/DNA ratio, whole body lipid and protein content, and Hsp60 and Hsp70 levels but higher protein efficiency ratio, and whole body moisture content than larvae fed the two higher feeding rates. Heat shock significantly induced Hsp60 and Hsp70 levels in the liver of all fish but they were lower in larvae fed the 5% than those fed 15 and 25% BW d(-1). Hsp70 level increased much more than Hsp60 after the heat shock Suggesting that Hsp70 is a more sensitive biomarker under our experimental conditions. (c) 2008 Elsevier B.V. All rights reserved.