Animal Science, Department of
First Advisor
Paul J. Kononoff
Date of this Version
5-2024
Document Type
Article
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science
Major: Animal Science
Under the supervision of Professor Paul J. Kononoff
Lincoln, Nebraska, May 2024
Abstract
When DDGS are fed to lactating dairy cattle, the observed response in energy supply, milk production, and methane production varies among studies. One potential reason for these observed discrepancies is the nature of the diet formulation itself. Furthermore, little research has been conducted to examine how dietary changes can affect dairy cattle manure composition and methane production in an anaerobic manure digester. In order to gain a better understanding of these topics, we conducted two experiments. The first experiment was conducted to test how the manipulation of lactating dairy cattle diets affects energy utilization, milk production, methane production, and manure output. Twelve lactating Jersey cows were arranged in a triplicated 4 × 4 Latin square design consisting of 4 periods of 28 days. Cows were randomly assigned to one of four treatments: CON (0% dried distillers grains with solubles (DDGS)); R-Alf (13% DDGS with alfalfa hay (AH) inclusion reduced from 16.6% to 8.36% of the diet); R-Gc (13% DDGS with ground corn (GC) inclusion reduced from 19% to 9.53% of the diet); R-GcAlf (6.5% DDGS with AH inclusion reduced from 16.6% to 13.9% of the diet and GC inclusion reduced from 19% to 16.3% of the diet). Treatments did not affect milk fat yield or methane production. Compared to CON, both DMI and gross energy intake increased when cows consumed R-Alf. We observed an increase in both ECM and milk protein yield and concentration compared to CON when cows consumed R-Alf. Manure output increased compared to CON when cows consumed R-Gc. When cows consumed R-Alf, manure volatile solids (VS) output was observed to increase compared to CON. The second experiment was conducted to test how diet manipulation may affect the chemical composition of manure and its subsequent methane production in an anaerobic digester. Manure samples were collected from lactating dairy cows in the first experiment. A biochemical methane potential test was conducted over two runs averaging 32 d. Observed methane production was corrected for the inoculum methane production. Manure substrate aNDFom was higher when cows consumed R-Gc or CON, and lower when cows consumed R-Alf or R-GcAlf. Compared to CON, Manure VS output increased when feeding R-Alf. Treatments did not affect manure methane or biogas production on a VS basis. Total manure methane potential increased when cows consumed R-Alf and R-Gc compared to CON.
Advisor: Paul J. Kononoff
Comments
Copyright 2024, Grant Michael Fincham. Used by permission