Sustainable Overwintering Systems for Beef Cows on the Canadian Prairies: Challenges and Solutions

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dc.contributor.authorDonohoe, Gwendolyn
dc.contributor.examiningcommitteeWittenberg, Karin (Animal Science) Tenuta, Mario (Soil Science) Schoenau, Jeff (University of Saskachewan, College of Agriculture and Bioresources, Department of Soil Science)en_US
dc.contributor.supervisorOminski, Kim (Animal Science) Flaten, Don (Soil Science)en_US
dc.date.accessioned2019-01-09T17:36:59Z
dc.date.available2019-01-09T17:36:59Z
dc.date.issued2019en_US
dc.date.submitted2018-12-21T00:56:58Zen
dc.degree.disciplineInterdisciplinary Programen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractThe goal of this thesis was to provide an in-depth description of winter bale grazing (BG) for beef cows, including the impacts on animal, soil and forage productivity and the potential environmental costs and benefits. A winter trial with 60 pregnant beef cows was conducted over two, 21-day periods (P1 and P2) with the following treatments: drylot (DL), BG, and BG with supplementation (dried distillers grains with solubles; BGDG) at a rate of 8.3 kg cow-1 every three days. All treatments received low-quality (11% CP) forage ad libitum. Dry matter (DM) intake in P1 for the DL and BG systems was 13.4 and 12.2 kg cow-1 d-1 while average daily gain was 0.45 and -0.28 kg cow-1 d-1, respectively. Enteric methane emissions (L d-1 and % GEI) were greatest from the BG system in P1. Forage DM yield decreased by 68% following application of manure from the BGDG treatment compared to a control field and was attributed to smothering by waste feed. Concentrations of residual soil extractable nitrogen (N) and phosphorus (P) were 15 and 2.5 times greater, respectively, at the centre of bale placement areas compared to a control. Detailed grid soil sampling revealed that 40 area-weighted mean extractable N and P samples, collected in a 4:1 ratio from waste feed affected and unaffected areas of the field, were required to determine field mean nutrient status without compromising precision. A system-scale nutrient budget model was used to determine efficiency of N and P inputs in BGDG and DL systems. Surpluses were 448 and 225 kg N ha-1 and 52 and 26 kg P ha-1, and efficiency was 0.4 and -0.3% N and 8.7 and 12.1 % P for the BGDG and DL systems, respectively. This research provides scientific information regarding, DM intake, enteric methane and N and P surpluses from extensively overwintered beef cows. These studies suggest that in some production systems bale grazing may have increased enteric methane emissions and decreased nutrient utilization efficiency compared to DL systems. These results must be considered along with economic costs and benefits to more fully assess the sustainability of overwintering systems.en_US
dc.description.noteFebruary 2019en_US
dc.identifier.urihttp://hdl.handle.net/1993/33678
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectBale grazingen_US
dc.subjectBeef cowsen_US
dc.subjectWinter grazingen_US
dc.subjectEnteric methaneen_US
dc.subjectNutrient use efficiencyen_US
dc.subjectOverwintering beef cowsen_US
dc.subjectNutrient balanceen_US
dc.subjectSoil samplingen_US
dc.subjectSustainabilityen_US
dc.subjectEnvironmental indicatoren_US
dc.subjectCow productivityen_US
dc.subjectForage productivityen_US
dc.titleSustainable Overwintering Systems for Beef Cows on the Canadian Prairies: Challenges and Solutionsen_US
dc.typedoctoral thesisen_US
local.subject.manitobayesen_US
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