ENERGY AND AMINO ACID METABOLISM IN LACTATING JERSEY COWS CONSUMING FEED BYPRODUCTS

Authors

Kyle McLain, University of Nebraska - LincolnFollow

First Advisor

Dr. Paul Kononoff

Date of this Version

5-2020

Comments

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, 2020

Copyright 2020 Kyle Alvin McLain

Abstract

Animal protein byproducts are high bypass proteins commonly used in the dairy industry. These bypass proteins can escape the rumen to supply additional amino acids needed to support milk and protein yield. Two of the more popular animal protein byproducts used in the dairy industry are blood meal and hydrolyzed feather meal. In the first experiment, two flow meters were compared using headbox-style calorimeters. The objectives of the first study were to test mass flow meter (MFM) and volumetric flow meter (VFM) by measuring O2 consumption and CO2 production and to illustrate the effects of incomplete gas recovery on estimated energy partitioning. The gas recoveries were observed to be lower for the VFM than the MFM. The MFM resulted in higher performance than the VFM that was determined by the flow rate. Incomplete gas recovery can result in underestimates of heat production, thereby affecting estimates of whole-animal energy use. Our results indicate that MFM may be better suited for headbox-style indirect calorimetry to estimate heat production in lactating cows. In the second experiment, 12 multiparous lactating Jersey cows were used to evaluate the effect of feeding hydrolyzed feather meal with or without blood with rumen protected lysine on milk protein and energy utilization. Treatments were composed of hydrolyzed feather meal without blood and no rumen protected Lys (RP-Lys), hydrolyzed feather meal with blood and no RP-Lys, hydrolyzed feather meal without blood and RP-Lys, and hydrolyzed feather meal with blood and RP-Lys. Results suggest the hydrolyzed feather meal containing blood produces more milk and milk protein than hydrolyzed feather meal alone, which may be due to the increase supply of essential amino acids, observed by the blood plasma. Even though, total tract crude protein digestibility maybe lower for the hydrolyzed feather meal containing blood than hydrolyzed feather meal alone. Energy supply did not seem to be a factor in the increase production of milk and protein yield.