Academic literature on the topic 'Chaffey Dam'

SUMMARYChaffed lucerne hay was fed to wether sheep at two feeding frequencies (once a day (daily) and once an hour (hourly)) and at two levels of dry matter (D.M.) intake (700 (L) and 1020 (H) g/day). Sheep fed daily were slaughtered either prior to eating, immediately after eating ceased or 10 h after eating ceased to compare rumen, reticulum, omasum and abomasum pool sizes and particle size distributions within pools.Effects of level of intake, feeding frequency and time after feeding were confined mainly to the rumen which contained 77–91% of stomach D.M. Once-daily feeding resulted in a 2·6 fold variation in rumen D.M. pool size. Sheep fed hourly had a relatively small rumen and comparatively large reticulum D.M. pool. Diurnal changes in reticulo-rumen particle size pools are discussed in relation to the effectiveness of chewing.Particle size distribution in digesta was estimated by wet sieving. On average the proportion of D.M. retained on a sieve 1 mm or larger comprised 35, 28, 4 and 4% of D.M. in the rumen, reticulum, omasum and abomasum, respectively, D.M. passing a 0·25 mm sieve comprised 40, 46, 57 and 61% of D.M. in the respective organs.The reticulum usually contained significantly less D.M. retained on a 4 mm sieve than the rumen, and reticulum D.M. percentage was usually 3–5 units lower than rumen D.M. percentage. Reticulum digesta composition is discussed in relation to the efflux of particulate D.M. to the omasum.Chemical composition of rumen particulate D.M. retained on sieves > 0·25 mm was comparatively unaffected by intake level and feeding frequency. Analyses of particle composition showed a rapid loss of non cell wall constituents after feeding and an increasing contribution of rumination toward particle size reduction.

SummaryThis study examines the effect of sodium (Na) supplementation on the intake and digestibility of Na-deficient feed by cattle, and the potential applicability of faecal analysis to the diagnosis of Na deficiency in the field. Mature cattle fitted with oesophageal fistulae were fed chaffed Setaria sphacelata cv. Nandi hay ad libitum in metabolism cages, with and without a Na supplement (10 g Na daily as NaHCO3). In the first of two experiments the hay contained 0·44 g Na/kg D.M., and in the second, 1·05 g/kg. Prior to an unsupplemented treatment the animals were rapidly depleted of Na by removal of saliva via the fistula; Na status was assessed on the basis of the ratio Na/K in saliva.When the feed contained 0·44 g Na/kg, Na supplementation increased voluntary intake by 28% (P < 0·01) and digestibility by 12% (P < 0·05). No such responses were obtained in Expt 2, in which the feed contained 1·05 g Na/kg.Examination of available data suggests that a diagnosis of Na deficiency in cattle is indicated if the faecal Na concentration is below 1 g/kg D.M., and the ratio Na/K in faeces is less than 0·1. Further data are required to confirm these criteria, which should prove useful in the field when samples of saliva, the diagnostic criterion of choice, are not available.

Fusarium head blight (FHB) affects whole spikes of small grain plants, yet little is known about how FHB develops following infection, or about the concentration or progression of the mycotoxin deoxynivalenol (DON) in non-grain spike tissues. Fusarium mycotoxin levels in whole small-grain spikes are of concern to producers of whole-crop silage, as well as users of straw containing chaff for animal bedding or winter livestock rations. A 2-year field experiment was performed in Kinston, NC to reveal the time course of FHB development. Eight winter wheat cultivars with varying levels of FHB resistance were used in the 2006 experiment, and four of them were used in 2007. Plots were spray-inoculated with Fusarium graminearum macroconidia at mid-anthesis. Four durations of post-anthesis mist were applied: 0, 10, 20, or 30 days. Spike samples were collected and bulked by plot at 15, 25, 35, 45, 55, and 65 days after anthesis (daa); samples were separated into grain, glume, and rachis fractions. Increasing durations of post-anthesis moisture elevated grain DON and reduced the effect of cultivar on DON, presumably by affecting the expression of resistance, in all spike tissues. Fusarium-damaged kernels increased from early kernel-hard to harvest-ripe in both years. Percent infected kernels increased from medium-milk to harvest-ripe. During grainfill, DON concentrations declined in grain but increased in rachises and glumes, peaking at early kernel-hard, before declining. Higher mean and maximum DON levels were observed in rachises and glumes than in grain. Estimated whole-spike DON peaked at early kernel-hard. In a high-FHB year, whole-plant harvest for forage should be conducted as early as possible. Straw that may be consumed by livestock could contain significant amounts of DON in chaff, and DON can be minimized if straw is sourced from low-symptom crops. Cultivar FHB resistance ratings and disease data should be useful in predicting whole-spike DON levels. Overall, associations between grain DON levels in harvest-ripe and prior samples were stronger the later the prior samples were collected, suggesting limits to the possibility of predicting harvest-ripe grain DON from earlier levels.

Abstract Harvest weed seed control (HWSC) technology such as impact mills that destroy weed seeds in seed-bearing chaff material during grain crop harvest, has been highly effective in Australian cropping systems. However, the impact mill has never been tested in soybeans and weeds common to soybean production systems in the Midwest and Mid-Atlantic US. We conducted stationary testing of Harrington Seed Destructor (HSD) impact mill and winter burial studies during 2015-2016 and 2017-2018 to determine (i) the efficacy of the impact mill to target weed seeds of seven common weeds in Midwestern and five in Mid-Atlantic US, and (ii) the fate of impact mill processed weed seeds after winter burial. The impact mill was highly effective in destroying seeds of all the species tested, with 93.5-99.8% weed seed destruction in 2015 and 85.6-100% in 2017. The weak relationships (positive or negative) between seed size and seed destruction by impact mill, and high percentage of weed seed destruction by impact mill across all seed sizes indicate that the biological or practical effect of seed size is limited. The impact mill-processed weed seeds that retained at least 50% of their original size, labeled as potentially viable seed (PVS), were buried for 90 d over winter to determine the fate of weed seeds after winter burial. At 90 d after burial (DAB), the impact mill processed PVS were significantly less viable than unprocessed control seeds, indicating that impact mill processing physically damaged the PVS and promoted seed mortality over winter. A very small fraction (< 0.4%) of the total weed seed processed by the impact mill remained viable after winter burial. The results presented here demonstrate that the impact mill is highly effective in increasing seed mortality and could potentially be used as a HWSC tactic for weed management in this region.

This research investigated the factors influencing the structure of the phytoplanktori community in Chaffey Dam, which is located in sub-tropical Australia. In particular, the research aimed to determine the influence of light at time scales ranging from seconds to seasons, on the growth and photophysiology of the cyanobacterium Anabaena circinalis. On a large scale, field monitoring programs between 1987 and 1997 indicated that the phytoplankton community of Chaffey Dam was dominated by colonial or relatively large phytoplankton that move either with the aid of flagella or can be positively buoyant. Diatoms contributed only a minor component, which may be the result of the reservoir being stratified for much of the year. Several of the dominant taxa bloomed in each of the seasons during the eleven year period, with some blooms lasting >9 months, indicating that environmental variability between seasons can be low. In contrast to other studies, A. circinalis was more likely to grow and bloom during the cooler months (March-October). A two-year intensive monitoring program (1995-1997) identified a seasonal progression that was similar in both years. Chlorophytes occurred in spring, Ceratium in mid summer, a relatively clear period in February, A. circinalis in March and cryptomonads in winter. On a smaller scale, short-term (2-3 day) in-situ and laboratory enclosure experiments found that the light and nutrient requirements of the dominant taxa varied. In comparison to most other phytoplankton, A. circinalis cells disappeared at very rapid rates when supplied irradiances <10 (umol photons m-2 s-1. Over several days of darkness, the filaments broke apart and the cell numbers declined. The experiments also showed that at certain times, field populations of A. circinalis were subject to high losses at all irradiances. Laboratory studies investigating the influence of inter- and intra-daily changes in light availability showed that the growth rate of A. circinalis was not affected by the frequency of daytime light:dark cycles, indicating that the rate of water mixing will not have major influence on its growth if the total daily light dose is maintained. It was also found that A. circinalis cultures did not accumulate large reserves of energy in the form of carbohydrate, other than that required for one night. This strategy may enable the colonies to have a high level of buoyancy each morning so that they float quickly to the surface waters and obtain sufficient light each day to minimise losses. However, this strategy limits the ability of A. circinalis to grow and maintain vital cell processes during extended periods of low irradiances and may be a factor causing them to be susceptible to cell breakdown. Weekly measurements of algal growth rates in Chaffey Dam identified two factors that may have acted singly or simultaneously to influence the development of A. circinalis blooms during 1996 and 1997. The blooms developed during a 4-6 week period when the mean irradiance in the surface mixed layer (SML) was sufficient to prevent high losses. Secondly, the blooms developed when soluble phosphorus in the epilimnion was relatively high but soluble nitrogen was low. This may have favoured A. circinalis, which has the potential to fix atmospheric nitrogen. The decline of A. circinalis blooms was correlated with a deepening of the SML and a reduction of the mean daytime irradiance within the SML. Their decline did not appear to be related to nutrient limitation or to changes in zooplankton concentrations. This research also developed a physiological technique for tracking daily changes in the mean daytime irradiance of A. circinalis and for estimating cell growth rate. This method is based on chlorophyll-a fluorescence quenching analysis of the state transition mechanism, which regulates light availability between the photosystems. The mean daytime irradiance of A. circinalis showed a strong relationship with the degree of non-photochemical quenching (qn), whereas the relative change to the maximum fluorescence showed a strong relationship with cell growth. It is anticipated that this method will provide a useful research tool for determining the relative importance of light and other factors on the net growth of A. circinalis and other cyanobacteria.

The dichotomies Weight/Lightness and Form/Idea formed the theory and the practice of Art, existing a correspondence between them. The weight exists thanks to the existence of a form that is made of matter; in the other hand, the lightness comes from the idea that is always present when the creation exists. This dichotomies were always interconnected during the centuries, and there are variations in relevancy of form and/or idea. In sculpture´s tradition, the physical weight was a essential reality, and the idea of sculpture, without the immaterial side was underlined to the form. During the centuries, new artistic approaches were born and re-born focused on the frailty, lightness and idea of the artistic object, fact that came to cancel the classic notion of work of art. The concept of image became the focus of the esthetical experience of the subject, which alone, tended to substantiate the artistic object itself. In the same way that lightness, when taken to the extreme, and despite the tridimensionality materiality of the object, begun to relate the art with the own action of the body, the gesture of the artist, rising both to the status of art