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The use of condensed tannins and nitrate to reduce enteric methane emission and enhance utilization of high-forage diets in sheep
Full text linkThesis (PhD)--University of Pretoria, 2019.Methane emission in ruminant production is not only a global greenhouse gas, but also a loss of feed energy. Therefore, there is huge interest in identifying mitigation strategies that reduce ruminant derived methane, which guarantees sustainable ruminant production. Tannins have been reported to inhibit methanogenic activity, but may also limit feed intake and nutrient digestibility. While dietary nitrate has been noted as an efficient hydrogen sink in the rumen, its effectiveness may be dependent on the application method among others. The objectives of this study are: (i) to evaluate the effects of nitrate supplementation and nitrate treatment on the in vitro digestibility and methane production in Eragrostis hay; (ii) evaluate the effect of supplementing acacia tannin extract and nitrate on feed intake, nutrient digestibility, methane emission and health status of Merino lambs; (iii) prepare and evaluate an encapsulated acacia tannin extract formulation suitable for ruminants; (iv) evaluate the effect of encapsulated acacia tannin extract on feed intake, nutrient digestibility and enteric methane emission in Merino rams. A series of experiments (laboratory trials, and stall-feeding experiments) were conducted at the NUTRILAB and Hatfield Experimental Farm of the University of Pretoria, South Africa to evaluate the potential improvements in the use of nitrate and tannin extract using Sheep as model animal.
Treating Eragrostis hay with urea improved its in vitro organic matter digestibility better than treatment with nitrate. However, nitrate treatment significantly reduced enteric methane and improved digestibility compared with the control, this suggests that nitrate could be incorporated as a hydrolytic agent in treating poor-quality roughage feeds, with the aim of improving their utilization. The combination of urea or calcium nitrate with or without Acacia tannin extract as dietary supplements in a growth trial revealed that lambs receiving nitrate-based TMR diets experienced superior growth performance compared to those on the urea-based TMR diets. Meanwhile, tannin inclusion did not improve growth or reduced methane emission from the lambs irrespective of the non-protein nitrogen source. A slight increase in haemoglobin, haematocrit and RBC count was associated with the use of calcium nitrate compared to urea. In this study, no clinical or subclinical signs of morbidity or tannin intoxication symptom was detected from the haematology and biochemical parameters evaluated in the Merino lambs.
The trial on the preparation and evaluation of an encapsulated Acacia tannin extract (ATE) showed that Gum Arabic-maltodextrin and native starch could only encapsulate the tannin extract at low inclusion levels while the in vitro release was not sustained. However, palm oil was found to be an effective wall material in encapsulating ATE using the double phase solid-in-oil-in-water encapsulation method where up to 80% w/w inclusion of tannin extract in the lipid wall material was achieved. This extract exhibited good morphological characteristics and high encapsulation efficiency even under high loading percentage. The lipid-encapsulated extract significantly reduced enteric methane production in vitro. Under in vivo evaluation with cannulated Merino rams, encapsulated Acacia tannin extract resulted in considerable reduction in methane per neutral detergent fibre intake, compared to the crude extract.Animal and Wildlife SciencesPhDUnrestricte
In vitro methane production of eragrostis hay treated with graded levels of urea or nitrate
Full text linkUrea treatment of protein deficient feeds serve as a source of ammonia nitrogen supply for rumen fermentation. This
study was undertaken with the objective of determining the effect of treating Eragrostis curvula hay with varying levels
of urea or nitrate on digestibility and in vitro fermentation. Grass hay was sprayed with urea solution at 0.5%, 1.0%, and
1.5% DM and calcium nitrate was used as a replacement of urea on an iso-nitrogenous basis. This was followed by 30
days anaerobic storage in airtight bottles with each treatment having three replicates. Following anaerobic treatment, hay
samples were dried, milled and evaluated for their chemical composition, in vitro organic matter digestibility, and in
vitro fermentation and methane production. Feed treatment with both urea and nitrate reduced ADF content of hay, while
crude protein content was increased. In vitro organic matter digestibility of treated hays increased with inclusion levels
although urea recorded higher values than nitrate. Nitrate treatment significantly reduced in vitro methane by 14-33%
while there was no significant methane reduction in the urea treated diets. Total volatile fatty acid, ammonia N and pH
across treatments were statistically not different (P>0.05). While urea treatment seems to improve digestibility better, it
did not confer additional benefits when compared to nitrate treatment that provided the additional benefit of methane
reduction with an acceptable level of improvement in feed digestion and fermentation. Nitrate can thus be incorporated
into feed treatment to improve the nutritional value of poor quality hays.The
European Community’s Framework Program (FP7/2007–
2013) through the ANIMAL
CHANGE project (grant agreement no. 266018),
the Department of Science and Technology and the
National Research Foundation.http://www.thejaps.org.pkam2019Animal and Wildlife Science
Characterization of starch and gum arabic-maltodextrin microparticles encapsulating acacia tannin extract and evaluation of their potential use in ruminant nutrition
Full text linkOBJECTIVE : The use of tannin extract and other phytochemicals as dietary additives in ruminants is becoming more popular due to their wide biological actions such as in methane mitigation, bypass of dietary protein, intestinal nematode control, among other uses. Unfortunately, some have strong astringency, low stability and bioavailability, and negatively affecting dry matter intake and digestibility. To circumvent these drawbacks, an effective delivery system may offer a promising approach to administer these extracts to the site where they are required. The objectives of this study were to encapsulate acacia tannin extract (ATE) with native starch and maltodextrin-gum arabic and to test the effect of encapsulation parameters on encapsulation efficiency, yield and morphology of the microparticles obtained as well as the effect on rumen in vitro gas production.
METHODS : The ATE was encapsulated with the wall materials, and the morphological features of freeze-dried microparticles were evaluated by scanning electron microscopy. The in vitro release pattern of microparticles in acetate buffer, simulating the rumen, and its effect on in vitro gas production was evaluated.
RESULTS : The morphological features revealed that maltodextrin/gum-arabic microparticles were irregular shaped, glossy and smaller, compared with those encapsulated with native starch, which were bigger, and more homogenous. Maltodextrin-gum arabic could be used up to 30% loading concentration compared with starch, which could not hold the core material beyond 15% loading capacity. Encapsulation efficiency ranged from 27.7%±6.4% to 48.8%±5.5% in starch and 56.1%±4.9% to 64.8%±2.8% in maltodextrin-gum arabic microparticles. Only a slight reduction in methane emission was recorded in encapsulated microparticles when compared with the samples containing only wall materials.
CONCLUSION : Both encapsulated products exhibited the burst release pattern under the pH conditions and methane reduction associated with tannin was marginal. This is attributable to small loading percentages and therefore, other wall materials or encapsulation methods should be investigated.The Department of Science and Technology (DS&T), the National Research Foundation (NRF), of South Africa and the University of Pretoria.http://www.ajas.infoam2020Animal and Wildlife SciencesBiochemistryGeneticsMicrobiology and Plant Patholog
Efficacy of three heat-stable microbial phytases on growth performance and bone development and strength of broilers fed diets deficient in available phosphorus
Full text linkA total of 2340 as-hatched Cobb500 chicks were allocated to 9 treatments, each with 13 replicate pens to evaluate the effects of either three phytase enzymes in a P-deficient diet. Starter and finisher diets consisted of a positive control (PC) and negative control 1 and 2 (NC1 and NC2, respectively). The PC, NC1, and NC2 diets had Ca:avP (available phosphorus) ratios of 0.50, 0.33, and 0.43 in the starter feed, and 0.46, 0.22, and 0.35 in the finisher feed, respectively; NC1 diets were then supplemented with Phytaverse, Quantum Blue, and Axtra-PHY at 500 and 1000 FTU/kg. Enzyme type had significant effects on body weight gain, feed conversion ratio, and production efficiency factor during the 0–7-day period. Interactions between enzyme type and inclusion levels had a significant effect on feed intake (FI) at 1–21-day (P = 0.02) and 1–35-day (P = 0.031) age. While FI decreased as Axtra-PHY inclusion levels increased from 500 to 1000 FTU/kg feed, FI increased in birds supplemented with Quantum Blue, but with no effects on Phytaverse-supplemented birds. Increasing the enzyme dose to 1000 FTU/kg feed improved bone-breaking strength but did not affect growth performance, tibia ash, Ca, or P concentration of the birds.Un total de 2340 poussins Cobb500 éclos ont été alloués à neuf traitements, chacun avec 13 enclos répliqués pour évaluer la réponse des poulets à griller à trois enzymes phytases dans une diète déficiente en P. Les diètes de démarrage et de finition consistaient d’un témoin positif (PC — « positive control »), et témoins négatifs 1 et 2 (NC — « negative control »; NC1, NC2). Les diètes PC, NC1 et NC2 avaient des rapports Ca:P disponible (Ca:avP — « calcium:available P ») de 0,50, 0,33 et 0,43 dans la diète de démarrage; et 0,46, 0,22, 0,35 dans la diète de finition; les diètes NC1 étaient alors supplémentées de Phytaverse, Quantum Blue et Axtra-PHY à raison de 500 et 1000 FTU/kg. Le type d’enzyme a eu un effet significatif sur le gain de poids corporel, le taux de conversion alimentaire (FCR — « feed conversion ratio ») et le facteur d’efficacité de production (PEF — « production efficiency factor ») durant la période de 0 à 7 jours. Les interactions entre le type d’enzyme et les niveaux d’inclusion avaient des effets significatifs sur la consommation (FI — « feed intake ») aux jours 1 à 21 (P = 0,02) et jours 1 à 35 (P = 0,031) d’âge. Tandis que le FI diminuait avec l’augmentation des niveaux d’inclusion d’Axtra-PHY de 500 à 1000 FTU/kg d’aliments, le FI a augmenté chez les poulets ayant reçu des suppléments de Quantum Blue, et il n’y a pas eu d’effet chez les poulets ayant reçu les suppléments de Phytaverse. Augmenter la dose d’enzyme à 1000 FTU/kg d’aliments a amélioré la résistance aux fractures, mais n’a pas eu d’effet sur la performance de croissance, ni les cendres du tibia, ni les concentrations de Ca ou P des poulets.Novus Nutrition Products Africa.https://cdnsciencepub.com/journal/cjashj2023Animal and Wildlife Science
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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