50 Research Lane
50 Research Lane
Scapinello S.,University of Guelph |
Brooks A.S.,University of Guelph |
Brooks A.S.,50 Research Lane |
MacInnes J.I.,University of Guelph |
And 3 more authors.
Veterinary Immunology and Immunopathology | Year: 2011
Antimicrobial proteins in neutrophil granules exert their bactericidal activity both within the neutrophil phagolysosome and as components of neutrophil extracellular traps. This study evaluated the bactericidal activity of porcine neutrophil secretions against four bacterial pathogens of swine. Porcine neutrophils were treated with or without phorbol myristate acetate (PMA), then the resulting supernatants were incubated with Escherichia coli K-12, Streptococcus suis, Actinobacillus suis, or Pasteurella multocida, and the surviving colony forming units were enumerated. Supernatants of PMA-activated neutrophils killed an average of 95% of E. coli K-12 cells, relative to supernatants from untreated neutrophils. Inhibition of elastase activity using chloromethylketone (CMK) prior to PMA stimulation significantly reduced the bactericidal activity of the neutrophil supernatants; 57% of the PMA-induced bactericidal activity against E. coli K-12 was estimated to be elastase-dependent. The same neutrophil supernatants had lower bactericidal activity against S. suis, A. suis, and P. multocida, with 30%, 36% and 13% reduction in bacterial numbers, respectively. The cathelicidin porcine myeloid antimicrobial peptide (PMAP)-36 and lactotransferrin were among the proteins identified in the supernatants of PMA-stimulated neutrophils by mass spectrometry. These findings imply that elastase-activated proteins, such as cathelicidins, are partially responsible for the bactericidal effect of porcine neutrophil secretions, but non-elastase-dependent proteins such as lactoferrin may also contribute. Further, the secretions of activated neutrophils were effective in killing the avirulent E. coli K-12 but were less effective against the other bacteria tested, suggesting that these pathogens may have evolved mechanisms to resist neutrophil-mediated killing. © 2010 Elsevier B.V.
Groen M.J.,University of Guelph |
Groen M.J.,Wageningen University |
Steele M.A.,50 Research Lane |
Steele M.A.,University of Alberta |
DeVries T.J.,University of Guelph
Journal of Dairy Science | Year: 2015
The primary objective of this study was to determine the effect of straw inclusion levels on the feeding behavior of young, weaned calves adapted to a dry total mixed ration (TMR) composed of a multitextured concentrate and chopped straw. A secondary objective was to determine how developed feeding patterns persist after calves were switched to a conventional silage-based diet. Ten Holstein bull calves (91 ± 2.4. d of age, weighing 136 ± 12.3. kg) were assigned to 1 of 2 treatments: a TMR containing [dry matter (DM) basis] either (1) 85% concentrate and 15% chopped straw for 10 wk (wk 1 to 10) or (2) 85% concentrate and 15% chopped straw for 5 wk (wk 1 to 5), then 70% concentrate and 30% chopped straw for 5 wk (wk 6 to 10). After 10 wk, all animals were transitioned to a TMR containing (DM basis) 42.3% corn silage and 57.7% haylage for 2 wk (wk 11 to 12). During wk 1 to 5, all calves had similar DMI (5.5. kg/d), average daily gain (1.7. kg/d), feed efficiency (3.5. kg of DM/kg of gain), and eating time (151.9 min/d). During wk 6 to 10, calves transitioned to the 70% diet ate less DM (5.5 vs. 7.4. kg/d), grew more slowly (1.3 vs. 1.6. kg/d), sorted more against long forage particles (62.8 vs. 103.8%), and had greater feeding times (194.9 vs. 102.6 min/d). The difference in feeding time occurred only during the first 8 h after feed delivery. Despite similar DMI (5.2. kg/d) and average daily gain (1.1. kg/d) in wk 11 to 12, differences in behavior were observed resulting from previous diets. In wk 11 to 12, calves previously fed the 70% diet continued to have a longer meal immediately after feed delivery. Overall, the results indicate that diluting a dry TMR containing a multitextured concentrate and chopped straw with more straw resulted in calves spending more time feeding and having longer meals immediately after feed delivery; this feeding pattern carried over after calves were transitioned to a silage-based ration. © 2015 American Dairy Science Association.
Hubbard J.,University of Guelph |
LeBlanc S.,University of Guelph |
Duffield T.,University of Guelph |
Bagg R.,50 Research Lane |
Dubuc J.,University of Guelph
Canadian Veterinary Journal | Year: 2010
The objective of this study was to assess the effect of storage conditions on the accuracy of a milk test strip for ketosis. Storage at 21°C for up to 18 wk had little effect on accuracy for diagnosis and classification of subclinical ketosis.
Dubuc J.,University of Montréal |
Dubuc J.,University of Guelph |
Du Tremblay D.,University of Montréal |
Baril J.,50 Research Lane |
And 4 more authors.
Canadian Veterinary Journal | Year: 2010
The objectives of this study were to quantify the effect of 16 ppm of dietary monensin on milk production and composition of dairy cows, and to investigate factors having a potential impact on this effect. Data were generated from a total of 3577 Holstein dairy cows (47 herds) in Quebec enrolled in a herd-level, randomized clinical trial investigating the effects of monensin supplementation. Milk production and composition data were collected from monthly dairy herd improvement (DHI) testing. Monensin increased milk production by 0.9 kg/cow/d in cows under 150 days in milk (DIM) (P < 0.05). Monensin decreased milk fat percentage by 0.18 percentage points during the whole lactation (P < 0.05). This decreasing effect was larger for component-fed cows (P < 0.05) and for cows being fed low levels of dietary physically effective particles (P < 0.05) when compared respectively to cows fed total mixed ration and cows fed high levels of dietary physically effective particles. The results of this study suggest that monensin influences milk production and milk composition of dairy cows, and that diet composition and feeding system influence those effects.
Eckert E.,University of Guelph |
Brown H.E.,University of Guelph |
Leslie K.E.,University of Guelph |
DeVries T.J.,University of Guelph |
And 2 more authors.
Journal of Dairy Science | Year: 2015
Recent research has revealed potential advantages of feeding an elevated plane of nutrition to calves during the preweaning period. However, calves fed more nutrients preweaning may be more susceptible to depressed growth and weaning stress during the transition from liquid to solid feed. The objective of this study was to investigate the relationship between the age of weaning and feed intake, and its influence on growth, gastrointestinal development, and behavioral indicators in dairy calves fed an elevated plane of nutrition during the preweaning period. To meet this objective, 20 female Holstein calves were randomly assigned at birth to be weaned at 6 or 8 wk. Milk replacer (mixed at 150 g/L) was offered at 1.2 kg/calf per day in 2 meals until a 1-wk step-down, when meals were reduced by 50% 1 wk before weaning. Daily starter, chopped oat straw, water intake, and weekly body weights were measured until d 70 of life. To assess digestive tract development, rumen fluid, fecal, and blood samples were taken before and after weaning (d 35, 49, and 63) and analyzed for ruminal short-chain fatty acids, blood β-hydroxybutyrate, and fecal starch, respectively. Behavioral indicators of weaning stress, including vocalizing and non-nutritive oral behavior, were measured by visual observation for 1 h, 3 times per week, before the second feeding of the day during the period from 2 wk before weaning to 2 wk after weaning. The calves weaned at 8 wk compared with 6 wk had higher average daily gain for the week preweaning (0.79. ±. 0.09 vs. 0.34. ±. 0.10 kg/d) and postweaning (1.05. ±. 0.09 vs. 0.35. ±. 0.11 kg/d), and were heavier at d 70 (99.9. ±. 1.81 vs. 91.0. ±. 2.26 kg). From 5 to 8 wk of age, starter and water intakes were lower in calves weaned at 8 wk of age. However, overall starter intake did not differ during the last week of the experiment. Furthermore, calves weaned at 8 wk compared with 6 wk had higher starter intake for 1 wk preweaning (1.36. ±. 0.13 vs. 0.40. ±. 0.08 kg/d) and postweaning (2.51. ±. 0.20 vs. 1.16. ±. 0.15 kg/d). In both treatments, weaning increased ruminal short-chain fatty acids, blood β-hydroxybutyrate, and fecal starch, yet the differences between the week before and after weaning were greater for calves weaned at 6 wk compared with those weaned at 8 wk. Treatment × week relative to weaning interactions indicated that several behaviors varied between early- and later-weaned calves during the week before weaning; calves weaned at 6 wk tended to exhibit 75% more non-nutritive oral behavior and spent 55% less time ruminating, and 36% less time lying compared with calves weaned at 8 wk. Under the conditions of this study, the results suggest that calves fed an elevated plane of nutrition preweaning have higher starter intakes and average daily gain during the weaning period when weaning is extended from 6 to 8 wk of age. © 2015 American Dairy Science Association.
Aryee A.N.A.,McGill University |
Dutilleul P.,McGill University |
Paszti M.,50 Research Lane |
Simpson B.K.,McGill University
Fuel Processing Technology | Year: 2013
The optimum conditions for the preparation of fatty acid ethyl ester (FAEE) were investigated in three experiments to assess the linear, quadratic, and bilinear effects of temperature, enzyme load, and oil:alcohol molar ratio on FAEE yield. In each experiment, second-order polynomial models fitted to the FAEE yield data provided response surfaces at various reaction times (8 h-48 h). These models were generally significant (p < 0.05) and produced reliable and stable predictions, especially at 24 h and 36 h. At these reaction times, optimum conditions were found to be close to the center point values of the reaction variables (50 °C, using an enzyme load of 39.06 U, and an oil:alcohol ratio of 1:2). Fuel testing of the transesterified oils revealed various proportions of total and bound glycerol, acid number (AN), triacylglycerol (TAG), diacylglycerol (DAG), monoacylglycerol (MAG), and moisture. © 2012 Elsevier B.V. All rights reserved.