Date of Award

Spring 2020

Project Type

Dissertation

Program or Major

Animal and Nutritional Sciences

Degree Name

Doctor of Philosophy

First Advisor

Peter Erickson

Second Advisor

Drew Conroy

Third Advisor

Andre Brito de Fonseca

Abstract

ABSTRACT

PRESERVATION AND UTILIZATION OF WET BREWER’S GRAINS IN DIETS OF DAIRY HEIFERS

By

Eric Hatungimana

University of New Hampshire, May 2020

Three experiments were conducted. The objective of Experiment 1 was 2-fold: 1) to evaluate the effect of storage of wet brewer’s grains (WBG) treated with salt or a commercial preservative (PRES) on yeast and mold growth and in vitro dry matter digestibility (IVDMD) and 2) to evaluate in situ dry matter (DM) and protein digestibility of WBG treated with salt and PRES. Seven treatments were used for objective 1: control (0%), PRES (0.05%, 0.10%, 0.15%); or salt (1.4%, 2.6%, 3.8%) and were allocated randomly in duplicate to 14 plastic tubs containing of 48.5 kg of fresh WBG. For objective 2, 3 cannulated cows were used twice (same 3 cows) in a replicated 3×3 Latin square. The WBG was treated with 0% or 0.10% PRES or 2.6% salt and preserved for 1 wk before being used for the in situ experiment. Results showed that WBG treated with PRES had the least yeast counts. The WBG treated with salt (3.8%) and PRES (0.15%) had the least mold counts. Greater IVDMD was observed in WBG treated with salt. Treatment with 2.6% salt resulted in greater in situ DM and protein digestibility. Experiment 2 evaluated the growth performance and apparent total-tract nutrient digestibility of limit-fed diets containing WBG to Holstein heifers. Treatments were 0%, 10% and 20% of WBG on a DM basis, and diets were formulated to be limit-fed for dry matter intake (DMI) at 2.35% of body weight (BW) and provided 15% crude protein (CP) and 2.27 Mcal ME / kg of DM. Results demonstrated that DMI, BW, average daily gain (ADG) were not different among treatments. Skeletal measurements and body condition scores (BCS) were not different among treatments except for the change in heart girth and initial BCS. Apparent total- tract digestibilities of DM, organic matter (OM), CP, fat, and hemicellulose were greater or tended to be greater in heifers fed 0% and 20% WBG treatments than heifers fed 10 % WBG. Neutral detergent fiber (NDF), acid detergent fiber (ADF) and fat digestibilities were similar among treatments. During the digestibility phase, DMI tended to be greater for the 10% WBG treatment. Experiment 3 evaluated the effect of storage of WBG with incremental levels of salt on total-tract nutrient digestibility and purine derivative excretion in dairy heifers. Treatments were 0%, 0.8%, 1.6%, and 2.4% salt added to fresh WBG and stored for 4 days before being included in the diet at 20% on the DM basis. Diets (DM basis) were formulated to be limit-fed at 2.15% of BW to provide 14% CP and 2.27 Mcal ME/kg of DM. Results demonstrated that DMI was greater in heifers fed 1.6% salt diet while BW, ADG and feed efficiency were greater in heifers fed diets containing WBG treated with salt. Digestibility of DM, OM, and CP linearly decreased with increasing levels of salt in WBG. Urinary volume, allantoin, and uric acid excretion and total purine derivative excretion were not affected by treating WBG with salt. Mold and yeast counts were not different among treatments. The losses in WBG weight (fresh basis) linearly decreased as salt increased.

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