In the first of three experiments, four Holstein multiparous dairy cows, equipped with ruminal and duodenal cannulas, were used to determine the impact of different methods of treating soybean meal (SBM) on ruminal degradability and intestinal digestibility of CP and amino acids (AA). Solvent extracted SBM (SE), expeller SBM (EP), lignosulfonate SBM (LS) and heat and soy hulls SBM (HS) were incubated in the rumen, in nylon bags, for various intervals up to 48h. Additional samples incubated for 16 h were pre-treated with pepsin HCI, and then used for determination of intestinal digestibility either in situ (mobile bag technique) or in vitro. Treatment of SBM (EP, LS, HS) increased rumen undegradable protein (RUP), and AA availability in 30%. Estimates of intestinal digestibility of AA and CP were lower when measured in vitro than in situ. Among the treated SBM products, four EAA (Ile, Leu, Phe and Val) showed differences in availability, with values consistently lower for HS than for LS. The second experiment involved a comparative assessment of the availability of lysine in SE and rumen protected SBM products (EP and LS). Lysine availability was assessed either by the increment in plasma flux of 15N lysine, the increment in intestinally digestible lysine (using chromic oxide as a digesta marker) or by the use of a "plasma lysine response curve" designed to predict intestinally available lysine. The plasma Lys flux was not different between the different SBM products. However, SE + 70 g.d-1 omasal infusion of Lys (SE70) increased Lys flux by exactly 70 g.d -1 above the SE treatment. No differences were observed on duodenal Lys flow, post-ruminal digestion and digestible Lys between the SBM diets (SE, EP, LS). Irrespective of the method of assessment, lysine availability was not altered by the method of treating SBM. The third study evaluated the relative impact of supplying rumen-undegraded protein (RUP) versus altering the carbohydrate source on milk yield and efficiency N usage for milk production. Protein supplementation (SE and EP) increased DMI, whereas the inclusion of beet pulp (BP) replacing 50% of high moisture shelled corn decreased DMI. The results of this research suggest that, under normal conditions of feeding, supplying rumen protected SBM to enhance the supply of intestinally available essential AA does not improve lactation performance; providing beet pulp as a source of readily fermentable fibre also failed to affect milk yield or efficiency of N usage for milk production by dairy cattle.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.102961 |
| Date | January 2007 |
| Creators | Borucki Castro, Sylvia Irene. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Animal Science.) |
| Rights | © Sylvia Irene Borucki Castro, 2007 |
| Relation | alephsysno: 002603815, proquestno: AAINR32153, Theses scanned by UMI/ProQuest. |
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