Browsing by Author "Janzen, Eugene D."

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    Assessment and Mitigation of Pain During and After Castration in Beef Calves
    (2018-04-03) Meléndez Suárez, Daniela M.; Pajor, Edmond Anthony; Schwartzkopf-Genswein, Karen Shelley; Orsel, Karin; Janzen, Eugene D.; Caulkett, Nigel Anthony
    Castration is a painful common husbandry procedure done in order to reduce aggressive behaviour, avoid unwanted mating and improve meat quality. Physiological and behavioural changes indicative of pain/discomfort have been reported after castration; however castration is commonly performed without the use of pain control. There is a lack of science based guidelines on pain mitigation strategies for castration in beef calves. The objective of this thesis was to assess and mitigate pain associated with castration in young and weaned beef calves. The first part of the study focused on assessing acute pain. Indicators of acute pain were evaluated to assess the effect of band and knife castration in 1 week, 2 month and 4 month old calves, the effect of a single dose of subcutaneous meloxicam administered immediately before band and knife castration in 1 week old calves, and the effect of a single dose of subcutaneous meloxicam administered immediately before knife castration or the combination of knife castration and branding in 2 month old calves. The second part of the study consisted of assessing pain in weaned beef calves after knife castration up to 28 days after castration. Indicators of pain were evaluated to assess the effect of a single subcutaneous injection of meloxicam administered 6, 3 and 0 hours prior to knife castration and the administration of lidocaine or meloxicam alone or in combination prior to knife castration in weaned calves. Behavioural and physiological changes were observed after castration at all ages, however, a greater number of physiological and behavioural parameters showed differences in knife castrated compared to band castrated calves, after multiple painful procedures compared to single painful procedures and in older calves compared to young calves. A reduction in behavioural and physiological responses was observed in calves that received pain mitigation at different ages and after different castration methods. Effective and practical pain mitigation strategies identified at different ages and after different castration methods could be used to improve calf welfare post castration. These include subcutaneous administration of meloxicam to reduce pain and inflammation associated with castration and the use of lidocaine to block procedural pain.
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    Digital Dermatitis in Feedlot Cattle: Field Diagnosis and Economic Impact
    (2020-04-30) Cortés Saavedra, Julián A.; Orsel, Karin; Pajor, Edmond Anthony; Janzen, Eugene D.
    Digital dermatitis (DD) has emerged in North American feedlots, although feedlot performance and risk factors are not fully elucidated. Objectives of this thesis were to evaluate two potential risk factors associated with DD: foot and leg conformation and pen condition, as well as identify the economic impact of DD in feedlot cattle. No significant difference was detected between foot and leg conformation in cattle with and without DD. However, pens with “more mud than bedding” increased significantly the odds of cattle with DD (OR=8.55, CI: 4.0-18.4), as well as pens with “excessive mud” (OR=14.1, CI: 5.9-33.8). Also, pens with “more mud than bedding” and “excessive mud” had animals with significantly less ADG (-0.12 and -0.36 kg/d, respectively), compared to animals in dry pen condition. Hence, it is recommended to keep good pen conditions to decrease the odds of cattle developing DD, as it would increase feedlot performance. This can be managed through proper stocking density and strategic bedding, regardless of cattle’s foot and leg conformation. For the economic impact, not all type of cattle with DD were negatively affected, but fall placed steers, winter placed heifers and grass yearlings had a loss between $72 - $98 CAD per animal for the whole feeding period, compared to healthy cattle. Also, cattle with DD gained between 0.11 – 0.17 kg/d less relative to healthy cattle.
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    Effects of transportation to and commingling at an auction market on the bacterial communities of the respiratory tract of beef cattle
    (2018-07-12) Stroebel, Christina Maria; Timsit, Édouard; Alexander, Trevor W.; De Buck, Jeroen M.; Janzen, Eugene D.
    Commingling at auction markets is considered a major predisposing factor for bacterial bronchopneumonia (BP) in beef cattle. However, the effects of commingling on the respiratory tract bacterial communities is largely unknown. Therefore, the objective of the thesis was to study the effects of transportation to and commingling at an auction market on the nasopharyngeal and tracheal bacterial communities of recently weaned calves using culture-dependent and independent methods. Two groups of 30 Angus-cross heifers were studied from weaning at the ranches of origin to 28 d after arrival at a feedlot. For each group, half the heifers were either transported directly to a feedlot after weaning (RANC) or transported to and commingled at an auction market for 24 hrs before being placed in a feedlot (AUCT). Heifers from both groups received vaccines against major respiratory viruses and a parenteral injection of a long acting macrolide (tildipirosin) at on-arrival processing (d2). Deep nasal swabs (DNS) and trans-tracheal aspirates (TTA) were collected at weaning (d0) and at on-arrival processing at the feedlot (d2). Deep nasal swab sampling only was then repeated 7 days (d9) and 28 days (d30) after arrival. Bacterial culture and 16S rRNA sequencing did not reveal difference in the nasopharyngeal and tracheal bacterial communities between RANC and AUCT at any sampling days. However, both time after arrival and feedlot where calves were placed affected diversity and composition of the nasopharyngeal bacterial communities. In both groups, there was a reduction in bacterial diversity and a large increase in Mycoplasma after feedlot placement, especially seven days after on-arrival processing. Furthermore, we observed the horizontal transmission of a multi-resistant strain of Pasteurella multocida among calves at d9 and d30 in one of the two groups of heifers. Based on these findings, we concluded that transportation to and commingling at an auction market for 24 hrs did not significantly influence the composition and diversity of the nasopharyngeal and tracheal bacterial communities of recently weaned calves.