Showing papers by "Tim A. McAllister published in 2007"
University of Aberdeen1, Chinese Academy of Sciences2, University of Maiduguri3, Agriculture and Agri-Food Canada4, University of Delhi5, Texas A&M University6, Colorado State University7, University College Dublin8, Kansas State University9, Council of Scientific and Industrial Research10, Commonwealth Scientific and Industrial Research Organisation11, Nanjing Agricultural University12, University of Hamburg13, Joint Graduate School of Energy and Environment14
TL;DR: In this paper, the authors explore the constraints and barriers to implementation important for GHG mitigation in agriculture and also examine how climate and non-climate policy in different regions of the world has affected agricultural GHG emissions and how it may affect emissions and mitigation implementation in the future.
584 citations
TL;DR: Feeding up to 2% of the dietary DM as quebracho tannin extract failed to reduce enteric methane emissions from growing cattle, although the protein-binding effect of the que bracho tANNin extract was evident.
Abstract: Our objective was to determine if condensed tannin extract from quebracho trees (Schinopsis quebracho-colorado; red quebracho) could be used to reduce enteric methane emissions from cattle. The experiment was designed as a repeated 3 x 3 Latin square (4 squares) with 3 treatments (0, 1, and 2% of dietary DM as quebracho tannin extract) and 3 28-d periods. Six spayed Angus heifers (238 +/- 13.3 kg of initial BW) and 6 Angus steers (207 +/- 8.2 kg of initial BW) were each assigned to 2 squares. The measured condensed tannin content of the extract was 91%, and the basal diet contained 70% forage (DM basis). Feeding quebracho tannin extract had no effect on BW, ADG, or nutrient intakes. Furthermore, it had no effect on DM, energy, or fiber (ADF and NDF) digestibility, but apparent digestibility of CP decreased linearly (P < 0.001) by 5 and 15% with 1 and 2% quebracho tannin extract, respectively. There were no effects of quebracho tannin extract on methane emissions (g/d, g/kg of DM, % of GE intake, or % of DE intake). Feeding up to 2% of the dietary DM as quebracho tannin extract failed to reduce enteric methane emissions from growing cattle, although the protein-binding effect of the quebracho tannin extract was evident.
361 citations
TL;DR: Results of this study indicate that supplementing dairy cows with GAR and JUN essential oils improved feed digestibility in the rumen, but possibly at the expense of a reduction in the flow of bypass protein to the small intestine.
194 citations
TL;DR: In this article, the effects of essential oils (EO) and essential oil compounds (EOC) on in vitro rumen microbial fermentation were investigated, and the results showed that EOC compounds improved the performance of microbial fermentation.
Abstract: The objective of this study was to investigate the effects of essential oils (EO) and essential oil compounds (EOC) on in vitro rumen microbial fermentation. Treatments were: control (no additive),...
143 citations
TL;DR: This study showed that CIN exhibited antimicrobial activity in both CC systems, but the effects were more pronounced in the Rusitec than in the DF system, and supplementation of CIN at the concentration evaluated in this study may not be nutritionally beneficial to ruminants.
110 citations
TL;DR: The stability of IgY in simulated gastric fluid was greatly improved by encapsulation in chitosan-alginate microcapsules, and the residual activity was not affected by pH of the encapsulation medium.
Abstract: Chitosan-alginate microcapsules were evaluated as a method of oral delivery of IgY antibodies. Physical characteristics, encapsulation efficiency (EE%), the loading capacity for IgY (IgY loading percentage, %, w/w of microcapsules), gastro-resistance, and release characteristics of these microcapsules in vitro under varying pH were investigated. Optimum physical factors were established for preparation of homogeneous, spherical, and smooth microcapsules. IgY loading% was not significantly altered by pH of the encapsulation medium. Encapsulation efficiency was highest (73.93%) at a pH of 3.5, above which EE% decreased significantly (p < 0.05). IgY was released from microcapsules upon exposure to simulated intestinal fluid (SIF, pH 6.8), and decreasing pH increased significantly IgY release (p < 0.05). The stability of IgY in simulated gastric fluid (SGF, pH 1.2) was greatly improved by encapsulation in chitosan-alginate microcapsules, and the residual activity was not affected by pH of the encapsulation medium. Moreover, microencapsulated IgY was significantly resistant to pepsin hydrolysis. This approach may enable intact IgY to reach target microorganisms within the lower digestive tract.
95 citations
TL;DR: Current research suggests that the passage of dietary DNA fragments across the intestinal wall is a natural physiological event, the likelihood of which is dependent on their concentration in the feed, as well as methods for detecting and quantifying GM plants in feeds.
70 citations
TL;DR: Conditioning calves prior to transport allowed calves to better tolerate the stressors of transport and handling, as well as growth performance, and morbidity rates.
60 citations
TL;DR: Alfalfa and sainfoin were combined in ratios of 100:0, 75:25, 50:50, 25:75 and 0:100 in this paper.
47 citations
TL;DR: The observed diversity of microbial phytases in the rumen may account for the ability of ruminants to derive a significant proportion of their phosphorus requirements from phytate.
Abstract: Examples of a new class of phytase related to protein tyrosine phosphatases (PTP) were recently isolated from several anaerobic bacteria from the rumen of cattle. In this study, the diversity of PTP-like phytase gene sequences in the rumen was surveyed by using the polymerase chain reaction (PCR). Two sets of degenerate primers were used to amplify sequences from rumen fluid total community DNA and genomic DNA from nine bacterial isolates. Four novel PTP-like phytase sequences were retrieved from rumen fluid, whereas all nine of the anaerobic bacterial isolates investigated in this work contained PTP-like phytase sequences. One isolate, Selenomonas lacticifex, contained two distinct PTP-like phytase sequences, suggesting that multiple phytate hydrolyzing enzymes are present in this bacterium. The degenerate primer and PCR conditions described here, as well as novel sequences obtained in this study, will provide a valuable resource for future studies on this new class of phytase. The observed diversity of microbial phytases in the rumen may account for the ability of ruminants to derive a significant proportion of their phosphorus requirements from phytate.
46 citations
TL;DR: It was concluded that although the supplements tended to lower the number of protozoa in ruminal fluid, this decline was not sufficient to significantly decrease predation of bacteria.
TL;DR: In this article, a study was conducted to assess feasibility and greenhouse gas (GHG) emissions during co-composting of cattle mortalities and manure using a tractor-mounted front-end loader.
Abstract: Following outbreaks of bovine spongiform encephalopathy (BSE), fewer cattle mortalities are being rendered. Composting may be a viable on-farm alternative for disposal of cattle carcasses. A study was conducted to assess feasibility and greenhouse gas (GHG) emissions during co-composting of cattle mortalities and manure. Using a tractor-mounted front-end loader, windrows were constructed containing manure + straw (control; CK) or manure + straw + cattle mortalities (cattle mortality; CM). The composting process lasted 310 d. The windrows were turned twice, at days 93 and 211, using either a tractor-mounted front-end loader or a specialized shredder bucket. Maximum windrow temperatures were >50 °C for 36 out of 92 d (before first turning) and 142 out of 208 d (after first turning) for the CM treatment and cattle mortalities were completely decomposed except for a few large bones. The cumulative CO2 and CH4 emissions were significantly affected by the mortality treatment, but not by the turning technology or their interactions. Significantly higher CO2 (53.6 g d−1 m−2) and CH4 (2.204 g d−1m−2) emissions were observed during the co-composting of cattle mortalities than manure composted with straw (23.0 and 0.742 g d−1m−2 for CO2 and CH4, respectively). Similarly, N2O emissions were higher with mortalities than without and, for the CM treatment only, higher with shredder bucket than front-end loader turning. In the final compost, CM had higher TN and NH
4
+
-N contents than CK while TC and the C/N ratio were higher with compost turned with the front-end loader than with the shredder bucket. In conclusion, composting was an effective means of disposing of cattle mortalities, but did increase GHG emissions and the N content in the final compost. It is not known if GHG emissions are different than those that would be released from natural decomposition of carcasses. The higher N content in compost containing mortalities would increase its agronomic value.
TL;DR: The aim is to evaluate the potential for polyclonal antibodies targeting enterohaemorrhagic Escherichia coli virulence determinants to prevent colonization of host cells by E. coli O157:H7.
Abstract: Aim: To evaluate the potential for polyclonal antibodies targeting enterohaemorrhagic Escherichia coli (EHEC) virulence determinants to prevent colonization of host cells by E. coli O157:H7.
Methods and Results: Rats and laying hens were immunized with recombinant proteins from E. coli O157:H7, EspA, C-terminal intimin or EscF. Rat antisera (IgG) or chicken egg powders (IgY) were assessed for their ability to inhibit growth and colonization-associated processes of E. coli O157:H7. Mammalian antisera with antibodies to intimin, EspA or EscF effectively reduced adherence of the pathogen to HeLa cells (P 0·05).
Conclusions: Antibody preparations targeting EHEC adherence-associated factors were effective at preventing adhesion and intimate colonization-associated events.
Significance and Impact of the Study: This work indicates that immunotherapy with anti-adherence antibodies can reduce E. coli O157:H7 colonization of host cells. Passive immunization with specific antibodies may have the potential to reduce E. coli O157:H7 colonization in hosts such as cattle or humans.
TL;DR: In this article, three open-air mortality compost windrows were constructed in January (JAN) and February (FEB) of 2004 in the cold, semi-arid climate of southern Alberta, Canada.
Abstract: After imposition of fees for disposal of cattle carcasses by the rendering industry, on-farm methods of mortality disposal are being investigated. Three open-air mortality compost windrows were constructed in January (JAN) and February (FEB) of 2004 in the cold, semiarid climate of southern Alberta, Canada. Windrow A included a base of barley straw a minimum of 46 cm thick, a layer of cattle mortalities (n=12) and a layer of stockpiled manure (minimum of 46 cm) covering the mortalities. Windrows B and C also had a bottom layer of barley straw, with windrow B containing 9 mortalities in 2 layers and windrow C containing 12 mortalities in 3 layers. Due to ambient temperatures > 0°C, carcasses (range 236 to 673 kg) were frozen at the time of windrow construction. Type ‘T’ thermocouples were embedded at the base of B and C windrows and temperatures within 120 cm of the surface were measured using a stainless steel dial probe. Windrows were turned 3 times at 3 mo intervals. Samples were collected from initial ...
TL;DR: The acetyl CoA carboxylase reference gene was selected as a reference gene for the detection and quantification of GM alfalfa, and two qualitative polymerase chain reaction (PCR) assays were designed to detect and quantify the plant's adventitious presence.
Abstract: Genetically modified (GM) alfalfa (Medicago sativa) was marketed for the first time in 2005. For countries with established thresholds for GM plants, methods to detect and quantify their adventitious presence are required. We selected acetyl CoA carboxylase as a reference gene for the detection and quantification of GM alfalfa. Two qualitative polymerase chain reaction (PCR) assays (Acc1 and Acc2) were designed to detect alfalfa. Both were specific to alfalfa, amplifying DNA from 12 separate cultivars and showing negative results for PCR of 15 nonalfalfa plants. The limits of detection for Acc1 and Acc2 were 0.2 and 0.01%, respectively. A quantitative real-time PCR assay was also designed, having high linearity (r > 0.99) over alfalfa standard concentrations ranging from 100 to 2.0 x 10(5) pg of alfalfa DNA per PCR. The real-time PCR assay was effective in quantifying alfalfa DNA from forage- and concentrate-based mixed diets containing different amounts of alfalfa meal.
TL;DR: The final CM compost had higher total N, total C, and mineral N content (NO3*+ NO2* + NH4+) than did CK compost and therefore has greater agronomic value as a fertilizer.
Abstract: Composting may be a viable on-farm option for disposal of cattle carcasses. This study investigated greenhouse gas emissions during co-composting of calf mortalities with manure. Windrows were constructed that contained manure + straw (control compost [CK]) or manure + straw + calf mortalities (CM) using two technologies: a tractor-mounted front-end loader or a shredder bucket. Composting lasted 289 d. The windrows were turned twice (on Days 72 and 190), using the same technology used in their creation. Turning technology had no effect on greenhouse gas emissions or the properties of the final compost. The CO2 (75.2 g d(-1) m(-2)), CH4 (2.503 g d(-1) m(-2)), and N2O (0.370 g d(-1) m(-2)) emissions were higher (p < 0.05) in CM than in CK (25.7, 0.094, and 0.076 g d(-1) m(-2) for CO2, CH4, and N2O, respectively), which reflected differences in materials used to construct the compost windrows and therefore their total C and total N contents. The final CM compost had higher (p < 0.05) total N, total C, and mineral N content (NO3*+ NO2* + NH4+) than did CK compost and therefore has greater agronomic value as a fertilizer.
TL;DR: Jugular cannulas, heart rate monitors and radio transmitters were used to non-invasively collect physiological data on British cross-bred steers transported in groups of four or five for 3 h and returned to their home pens.
Abstract: Nineteen British cross-bred steers (623 ± 10.6 kg) were transported in groups of four or five for 3 h and returned to their home pens. Jugular cannulas, heart rate (HR; BPM) monitors and radio transmitters were used to non-invasively collect physiological data. Heart rate (n = 13) was lower during highway travel (83.5 ± 3.15, P > 0.05) compared with pre-loading (118.9 ± 3.19, P 0.50). Increases in HR (P < 0.0...
TL;DR: The presence of glyphosate did not increase selective pressure for gene transfer of DNA encoding glyphosate resistance from Roundup Ready® canola meal to ruminal bacteria.
Abstract: BACKGROUND: The impact of glyphosate on ruminal fermentation, selective pressure on ruminal bacteria and horizontal transfer of the gene encoding 5-enolpyruvylshikimate-3-phosphate synthase (epsps) to ruminal bacteria was studied using batch culture with glyphosate-tolerant (Roundup Ready®) canola meal as substrate.
RESULTS: A glyphosate concentration × time interaction (P < 0.05) occurred when glyphosate (0–100 mmol L−1) was included in in vitro ruminal incubations with a diet containing 150 g kg−1 Roundup Ready® canola meal (Experiment 1). Glyphosate at 50 and 100 mmol L−1 inhibited fermentation. In Experiment 2, epsps fragments were detected in plant debris for up to 16 h of incubation using primer sets that amplified three fragments (62, 108 and 300 bp) of DNA spanning the transgenic construct. Persistence was affected by fragment size but not by glyphosate concentration (0, 10 or 60 mmol L−1). Extensive polymerase chain reaction assays provided no evidence of acquisition of epsps by feed- or fluid-associated bacteria during fermentation. A glyphosate concentration × time interaction (P < 0.05) was observed for all fermentation parameters measured, and glyphosate caused a general inhibition of fermentation.
CONCLUSION: The presence of glyphosate did not increase selective pressure for gene transfer of DNA encoding glyphosate resistance from Roundup Ready® canola meal to ruminal bacteria. Copyright © 2007 Society of Chemical Industry
TL;DR: Growth performance, carcass characteristics and pork quality were evaluated for pigs fed barley and wheat-based diets, which included meal from conventional or transgenic glyphosate-tolerant (Roundup-Ready®) canola.
Abstract: Growth performance, carcass characteristics and pork quality were evaluated for pigs fed barley and wheat-based diets, which included meal from conventional or transgenic glyphosate-tolerant (Roundup-Ready®) canola. One hundred and forty-four pigs (72 gilts and 72 barrows) weighing 30 ± 3 kg were assigned, three to a pen, on the basis of gender and weight to receive one of four dietary treatments formulated using canola meal from two commercial sources (COM1 and COM2), non-transgenic parental control (PCC) or transgenic (RRC) canola. Pigs were fed a grower diet (75 g kg-1 canola meal) until 60.5 ± 4.0 kg and then a finishing diet (150 g kg-1 canola meal) to 108.6 ± 7.3 kg at slaughter. Pigs receiving the COM1 and COM2 diets had an overall higher (P 0.05) among diets. ...
TL;DR: In this article, an experiment was conducted to determine the effect of a liquid lignite coal extract (LC; pH = 3.5) on gas emissions and the chemical composition of feedlot cattle manure.
Abstract: An experiment was conducted to determine the effect of a liquid lignite coal extract (LC; pH = 3.5) on gas emissions and the chemical composition of feedlot cattle manure. Eighty steers were randomly divided into four groups, penned individually, and fed a barley grain – barley silage diet sprayed with 0 (control), 0.5, 1.0 or 2.0 L of LC per tonne of dry matter. Manure samples (mixture of excreta and wood chips) were collected 25, 53, 81, 109 and 150 d after the LC was included in the diet. Inclusion of LC in the diet reduced both the pH and dissolved NH3+ NH4+ content of manure collected on days 25 and 53. Ammonia emissions were also significantly reduced on these occasions. In addition, butyric acid content was higher and isovaleric acid content lower in manure from cattle fed LC compared with manure from control cattle. Levels of nitrate, total volatile fatty acid (VFA), acetic, isobutyric, propionic, and capric acid in manure were not altered by the inclusion of LC in the diet. Greenhouse gas emissio...
Journal Article•
TL;DR: Although supplementation with greater amounts of feather meal or vitamin E may have been necessary to significantly affect factors related to feedlot AIP, increased supplementation would be uneconomical for commercial feedlots, given the relatively low incidence of AIP.
Abstract: We evaluated the effects of feeding 1.5% cysteine-rich feather meal or 550 IU of vitamin E for 40 d before slaughter on the rates of death and emergency slaughter due to acute interstitial pneumonia (AIP) in commercial feedlots. Blood and lung tissue were collected at slaughter from 83 animals clinically diagnosed with AIP, 40 asymptomatic penmates, and 40 heifers receiving either feather meal (20) or vitamin E (20); the left lung was subsampled for histologic examination. Blood and lung tissue were analyzed for thiol adducts of 3-methyleneindolenine (3ME) and reduced glutathione. Supplementation with feather meal or vitamin E had no effect on the rates of death and emergency slaughter attributable to AIP and did not influence the levels of 3ME or reduced glutathione in blood or lung tissue. Although supplementation with greater amounts of feather meal or vitamin E may have been necessary to significantly affect factors related to feedlot AIP, increased supplementation would be uneconomical for commercial feedlots, given the relatively low incidence of AIP.