A comparison of two methods for determining titanium dioxide marker content in broiler digestibility studies

The use of inert markers in broiler diets eliminates the need to quantitatively evaluate feed intake and excreta output to determine diet digestibility, and enables nutrient uptake at specific points along the gastrointestinal tract to be examined. Titanium dioxide (TiO2) is commonly used for this purpose and measured using a UV spectrophotometric assay. Two experiments were conducted to observe whether an inductively coupled plasma optical emission spectrophotometer (ICP-OES) assay is able to replace the UV-spectroscopy assay for rapid analysis of TiO2 in broiler feed and ileal digesta samples. In the first experiment, TiO2 was added at 5g/kg to 19 broiler diets. Ross 308, male broilers (n=452) fed these diets were involved in a series of digestion studies to determine ileal digesta recovery of TiO2. In the second experiment, defined amounts of TiO2 were added to ileal digesta samples from Ross 308, male broilers (n=176) and TiO2 recoveries were determined

Evaluation of chromium oxide and titanium dioxide as inert markers for calculating apparent digestibility in sheep

he objective of the present study was to evaluate two markers: chromium oxide (Cr2O3) and titanium dioxide (TiO2). We evaluate the interaction between Cr2O3 and TiO2, and the techniques used to determine it, using atomic absorption spectrophotometry (AAS) and photometry simple (PS). We used six growing sheep distributed in a replicated Latin square 3×3 design, with adjustment for the residual error effect. The TiO2 and Cr2O3–TiO2 produced values similar to those obtained by total faecal collection (TFC) or the use of Cr2O3 alone, determined by AAS and PS. Digestibility of the marker/TFC ratio was similar (p>.05) between markers and technique. The use of TiO2 alone or in combination with Cr2O3 seems to be a suitable alternative to TFC and Cr2O3 to calculate apparent digestibility of the total digestive tract determined in sheep by PS and AAS.Guzman, MSc, was granted for a CONACyT fellowship during his studies in the University National Autonomous of Mexico. Dr. Gonzalez Ronquillo was granted for a CONACyT fellowship ‘Estacias sabaticas en el Extranjero, 2014’. This project was supported by UNAM, DGAPA - PAPIIT [IN20600

Use of inert markers to predict diet composition, forage intake, digestibility and passage rate in sheep.

Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.The mechanisms that regulate intake and composition of selected diets in ruminants are complex and vary among animals of the same species and cross species. These are governed by highly variable aspects, which range from animal factors to physio-chemical properties of feeds. Understanding how ruminants select their diets is imperative to improve their utilisation of feed resources regarding the diversity of plant species that can be used as their sources of feed. The objectives of the study were to: (1) determine the effect of group feeding and removal of dietary ingredient (Sorghum bicolor) on diet selection, nutrient and total dry matter intake, and digestibility in choice-fed sheep; (2) asses the effect of animal stocking rate on dry matter and nutrient intake, botanical composition, nutrients selected, total tract digestibility and passage rate of diet consumed by sheep; and (3) predict dry matter and nutrient intake, botanical composition, nutrients selected and total tract digestibility using inert markers. Twelve sheep (mean weight: 29.7 ± 4.63 kg) were assigned to three treatments. In treatment one, five feeds were fed to sheep fed as a group of 9 sheep (G). In the second treatment, five feeds were fed to sheep penned in isolation (I) and in the last treatment, four feeds with sorghum stover (SS) removed were fed to sheep penned in isolation (R). There were five experimental feeds: veld hay (VH), sorghum stover (SS) and maize stover (MS) fed ad-libitum, and Lucerne hay (LH) and bean straw (BS) fed at restriction levels of 0.15 and 0.35 kg/day per sheep, respectively, in a group or individually fed sheep. Diet compositions were similar (p >0.05) between sheep fed individually with or without SS. Similarity in proportion of these dietary ingredients consumed between R and I may be due to less selection of SS; therefore, its removal did not significantly influence consumption and selection of other dietary ingredients. Group feeding of sheep relative to individual feeding with similar dietary ingredients influenced selection of SS. Sheep fed individually had lower intake levels of SS. Establishment of a dominance hierarchy in group-fed sheep may have caused dominant animals to feed on poor quality stovers just to prevent sheep lower in the hierarchy from eating resulting in high consumption of stovers. Fifteen sheep (mean body weight 46.5 ±3.3 kg) were blocked by weight into four groups and each sheep was randomly allocated to four stocking rates (treatments) of 1, 2, 4 and 8 sheep per pen and fed: MS, SS, and VH. All feeds were fed on separate feeding troughs ad-libitum. To evaluate the effect of animal stocking rate (SR) on passage rate of digesta, one sheep each from stocking rates one (SR1) and two (SR2) animals per pen and two sheep each pair from stocking rates of four (SR4) and eight (SR8) animals per pen were randomly selected and dosed with Ytterbium (particulate) and cobalt-ethylenediamine tetraacetic acid (Co-EDTA; liquid) markers. An optimisation procedure was used to predict diet selection by minimising the sum of the squared discrepancies between the proportional concentration of markers (acid insoluble ash: AIA, modified acid detergent fibre: MADF, and acid detergent lignin: ADL) in faeces (A) and their proportional concentration in dietary components (E) (MS, SS and VH), corrected for faecal recoveries of markers. Fractional passage rate (liquid and particulate) from both the rumen and in the hind gut, mean retention time, and total mean retention times across treatments were similar (p >0.05). Similarly, intake of dietary ingredients, nutrients (crude protein: CP, neutral detergent fibre: NDF and acid detergent fibre: ADF), total dry matter intake and composition of diets selected were not different across treatments. Selectivity index factors of diets selected were all within the range of 1.56-3.80, which reflected that animals were able to retain the diets they selected long enough in the gastro intestinal tract (GIT) for efficient digestion. Total tract digestibility and mineral intake (Ash) differed (p <0.05) in relation to animal stocking rate. Sheep in SR2 had the highest digestibility and consequently increased dry matter intake. Predicted dry mater intake and total tract digestibility of a diet selected by sheep were less sensitive to correction of incomplete faecal recovery of the markers and they tended to be similar to observed dietary parameters. Therefore, inert markers can be used to predict several components of a diet selected by grazing sheep and other classes of ruminants

Investigation of the role of vacancy sources and sinks on the Kirkendall-effect on the nanoscale

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An investigation of the relationship between thermal imaging and digital thermometer

BACKGROUND: A number of research papers and theoretical clinical models summarising how temperature of the skin over the knee may be altered according to different pathological processes have been published. Thermal imaging (TI) is generally regarded as the ‘Gold’ or ‘reference’ standard for measuring skin temperature, however this technology is not widely accessible to most musculoskeletal physiotherapists working in clinical environments. This is largely due to the time required for analysis of the thermal images and high cost of the equipment. A digital thermometer (DT) is portable with a convenient display of results which could offer an inexpensive substitute. AIM: This study determined interchangeability between thermal imaging and a digital thermometer, using Bland-Altman limits of agreement, to determine skin temperature differences between right and left knees. METHOD: 71 healthy participants in the age group of 8 to 40 participated in the study. Data were collected in two phases. The first phase was as part of a public engagement event at the Lancashire Science Festival where school children were invited to learn about science. The second phase of data collection took place as part of a PhD study where staff and students at the university were recruited via electronic advert and posters displayed around the campus. All subjects were free from lower back or lower limb problems and had not had any previous lower limb surgery. RESULTS: Matched paired t tests showed no significant difference between temperature difference between right and left using DT and TI (t= 1.41, df= 69, P= 0.08). The DT and TI were interchangeable to measure knee skin temperature difference with a limit of agreement of -0.64 and 0.75; this limit of agreement is acceptable based on previous literature where skin temperature differences between affected and non-affected knees are equal to or greater than 1°C. CONCLUSION: This study concludes that an inexpensive handheld digital thermometer shows acceptable agreement with a thermal imaging camera. Clinically a handheld digital thermometer has the potential to play an important role in the localized assessment of skin temperature in physiotherapy and can offer an inexpensive substitute to thermal imaging; due to the massive difference in cost it is worth considering the adoption of digital thermometry in routine musculoskeletal physiotherapy practice

The Kirkendall effect in solid state diffusion

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