Date of Award

Winter 2025

Project Type

Dissertation

Program or Major

Agricultural Sciences

Degree Name

Doctor of Philosophy

First Advisor

Andre Brito

Second Advisor

Sabrina Greenwood

Third Advisor

Jana Kraft

Abstract

Dietary inclusion of seaweed in ruminant diets has been studied for more than 5 decades. Early research in seaweed focused primarily on potential health benefits, but recent interest has shifted the paradigm for its use as a nutritional tool to mitigate greenhouse gas emissions. As new seaweeds are identified for their ability to reduce gas emissions, the pendulum will swing once more to understand the impact seaweeds have on ruminant health and production. The overall objective of this dissertation is to investigate digestibility and fermentation, as well as alterations in metabolic and mineral status in ruminants fed various seaweed species. Chapters 2, 3, and 4 are formatted to the standards required for publication in the Journal of Dairy Science. An experiment was conducted feeding 1% dry matter inclusion of Ascophyllum nodosum, Alaria esculenta, or an Alaria esculenta and Palmaria palmata blend in a single-flow continuous culture fermentation system. Changes in gas (H2S, CH4, CO2), digestibility, and fermentation of feed were measured. Fermenters fed A. esculenta had a 3% greater ADF digestibility compared with A. nodosum, while no other differences in digestibility were observed. Furthermore, the A. esculenta and P. palmata blend decreased lactic acid production by 65% compared with the control group, while no differences in other organic acids or ammonia nitrogen were observed across treatment groups (Chapter 2). In the second experiment, incremental amounts of A. nodosum (0, 170, and 340 g/d) were fed to mid-lactation Jersey cows to evaluate blood biomarkers prior to and during a feed restrictive diet. Feeding A. nodosum either before or during a feed restriction did not affect plasma concentrations of non-esterified fatty acids or cortisol. However, prior to feed restriction, cows receiving 170 g/d of A. nodosum had greater plasma glucose concentrations compared with control, whereas feeding 170 or 340 g/d of A. nodosum reduced plasma urea nitrogen. Greater supplementation of A. nodosum to the diet increased milk I concentration, while lowering milk transfer efficiency. Supplementation of A. nodosum to mid-lactation Jersey cows had minimal effects on metabolic status prior to and during a feed restriction (Chapter 3). In the third experiment, a 3% DM inclusion of Chondrus crispus was fed to mid-lactation Jersey cows during the summer grazing season to evaluate antioxidant and mineral status. Cows fed C. crispus had lower serum concentrations of P, Na, I, and Zn, and greater Co and Mo. Feeding C. crispus only increased milk concentrations of Se and total As, with no effect observed for all other minerals. Inclusion of C. crispus lowered concentrations of fecal Ca, Mg, Co, Cu, Fe, Mn, Se, Zn, Mo, Pb, and inorganic As, whereas K, S, and total As were greater. Cows fed C. crispus had greater concentrations of urine Ca, P, Mg, Cl, and K, while lower concentrations of urine S. Antioxidant activity including superoxide dismutase, catalase, and glutathione peroxidase were not altered by inclusion of C. crispus in the diet. Our data suggests that a 3% dry matter inclusion of C. crispus during grazing primarily altered mineral excretion in urine and feces, while only minimal changes in milk and serum mineral concentrations, and no changes in serum antioxidant activity (Chapter 4).

Download

Share

COinS