Date of Award

2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Animal Biosciences

First Advisor

Sarah Y. Morrison

Abstract

Many bacteria form biofilms, an extracellular polysaccharide (EPS) that allows adherence to surfaces and protection from environmental assaults. The molecular and cellular characteristics of certain biofilm-forming bacteria demonstrate inhibitory effects against pathogenic agents and interact positively with commensal gastrointestinal bacteria to promote growth and development. There is opportunity to expand understanding of their functionality as promoters of growth and development, complements to cleaning and disinfection procedures, and alternatives to antimicrobials, which is a relatively new area of research in intensive animal-rearing systems. More evidence is needed to elucidate the interplay of beneficial biofilms with other environmental factors and relationships to animal health and development, and current knowledge and gaps in the literature are discussed. This dissertation will examine application of beneficial biofilm-forming bacteria as 1) a complement to a cleaning procedure, and 2) direct-fed microbial interventions to influence gastrointestinal health, feed intake, and rumen development in the pre-weaned calf. In Chapter 2, we first develop an on-farm method to evaluate a multi-species, beneficial biofilm-forming cocktail of Bacillus spp. and Pediococcus spp. for adherence to naïve polyethylene calf hutch material, and second, to determine if application in situ to individual calf hutches post-cleaning (n=30) influenced surface recolonization by enteric pathogens. To our knowledge, this study is the first use in individual pre-weaned calf housing. Applying the beneficial biofilm-forming solution to calf hutches 24 h after cleaning influenced the microbial population on the surfaces and potentially reduced the presence of certain pathogenic bacteria on high-contact interior surfaces. We next explore, in Chapter 3, the use of the fermented cows’ milk beverage kefir as a practical and efficient on-farm probiotic supplement under different management conditions in. Holstein heifer calves (n=148) on three Northern New York farms were randomized at 3 d of age to receive either a control of 60 mL salable whole milk (or nothing) or 60 mL kefir 1x/d in liquid diet until 21 d of life. Although kefir was only supplemented until 21 d of life, increases in feed intake in supplemented calves on one farm suggests there may be residual metabolic or physiological benefit that merits further investigation. Production of EPS in kefir may be enhanced by co-fermenting with Saccharomyces cerevisiae. Chapter 4 outlines a practical laboratory methodology for evaluating four different concentrations of commercially available dried, activated distiller’s yeast or autolyzed yeast powder for EPS optimization in kefir. An inclusion rate of 1% autolyzed yeast powder achieved this objective. Chapter 5 discusses the effects of supplementing kefir fermented with or without 1% autolyzed yeast powder on dry matter intake, intestinal permeability, and rumen fermentation profile of Holstein calves. Holstein heifers (n=81) were randomized at 3 d of age to receive either 125 mL of salable whole milk (CON), 125 mL kefir (KEF), or 125 mL of kefir fermented with 1% autolyzed yeast powder (YAK) until 28 d of life. Rumen fermentation profile, starter intake, and body weight gain were improved in YAK calves compared with KEF and CON. This work provides more data to support the use of kefir as a practical probiotic supplement in calves and the implementation of beneficial EPS in calf-rearing environments.

Language

en

Number of Pages

228 p.

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