Manipulation of ruminal fermentation to alter milk fatty acid composition in dairy cows
| dc.contributor.advisor | Mutsvangwa, Timothy | en_US |
| dc.contributor.committeeMember | Christensen, Colleen | en_US |
| dc.contributor.committeeMember | Laarveld, Bernard | en_US |
| dc.contributor.committeeMember | McKinnon, John | en_US |
| dc.creator | Hobin, Morgan Rachelle | en_US |
| dc.date.accessioned | 2009-07-21T10:24:29Z | en_US |
| dc.date.accessioned | 2013-01-04T04:46:28Z | |
| dc.date.available | 2010-09-03T08:00:00Z | en_US |
| dc.date.available | 2013-01-04T04:46:28Z | |
| dc.date.created | 2009 | en_US |
| dc.date.issued | 2009 | en_US |
| dc.date.submitted | 2009 | en_US |
| dc.description.abstract | The objective of this study was to determine the effects of method of barley grain processing (dry-rolled vs. pelleted barley) and source of oilseed (ground canola vs. ground flaxseed), arranged as a 2 x 2 factorial, on feed intake, ruminal fermentation, nutrient flow to the duodenum, and milk production and composition in dairy cows. Eight Holstein cows (655 ± 69 kg; 83 ± 16 DIM) were used in a replicated 4 x 4 Latin square with 28-d periods. Cows in one square were fitted with ruminal and duodenal cannulae. Cows fed dry-rolled barley consumed 1.8 to 3.5 kg/d more (P = 0.02) DM than those fed pelleted barley; however, source of supplemental dietary fat had no effect on DM intake. Ruminal pH was lower (P = 0.045) in cows fed pelleted barley compared to those fed dry-rolled barley. Ruminal concentration of acetate was greater (P = 0.001), whereas ruminal concentration of propionate tended to be lower (P = 0.11), in cows fed dry-rolled barley compared to those fed pelleted barley; consequently, the acetate:propionate ratio was higher (P = 0.01) in cows fed dry-rolled barley compared to those fed pelleted barley. Ruminal concentration of total VFA was unaffected (P > 0.05) by diet. Source of dietary fat had no effect on ruminal digestion of OM, NDF, ADF or starch; however, ruminal starch digestion was slightly higher in cows fed pelleted barley compared to those fed dry-rolled barley (90.8 vs. 89.5%). Total dietary fatty acid intake was higher (P < 0.05) in cows consuming dry-rolled barley compared to those fed pelleted barley. Duodenal flow of C18:0 was lower, whereas that of C18:2n6c was higher (P < 0.05) in cows fed pelleted barley compared to those fed dry-rolled barley. Feeding flaxseed increased duodenal flows of C18:3n3, cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid compared to feeding canola. Milk yield was unaffected (P > 0.05) by diet; however, milk fat content was higher (P = 0.004) in cows fed dry-rolled barley compared to those fed pelleted barley. Milk fat content of C18:3 was higher (P = 0.005) in cows fed canola compared to those fed flax. Milk fat content of C18:3 and cis-9, trans-11 C18:2 were higher in cows fed pelleted barley compared to those fed dry-rolled barley with flax as the source of oilseed, but not with canola (interaction, P < 0.01). Milk fat content of saturated fatty acids decreased (P < 0.001) and that of polyunsaturated fatty acids increased (P = 0.003) in cows fed pelleted barley compared to those fed dry-rolled barley. In summary, milk fatty acid profiles were altered by method of grain processing and source of oilseed. | en_US |
| dc.identifier.uri | http://hdl.handle.net/10388/etd-07212009-102429 | en_US |
| dc.language.iso | en_US | en_US |
| dc.subject | Grain processing | en_US |
| dc.subject | Oilseed | en_US |
| dc.subject | Rumen fermentation | en_US |
| dc.subject | Milk fatty acids | en_US |
| dc.subject | Dairy cows | en_US |
| dc.title | Manipulation of ruminal fermentation to alter milk fatty acid composition in dairy cows | en_US |
| dc.type.genre | Thesis | en_US |
| dc.type.material | text | en_US |
| thesis.degree.department | Animal and Poultry Science | en_US |
| thesis.degree.discipline | Animal and Poultry Science | en_US |
| thesis.degree.grantor | University of Saskatchewan | en_US |
| thesis.degree.level | Masters | en_US |
| thesis.degree.name | Master of Science (M.Sc.) | en_US |