Animal Science Department

 

Date of this Version

Spring 5-9-2014

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 Professors Karla J. Jenkins and Terry J. Klopfenstein. Lincoln, Nebraska: May, 2014

Copyright (c) 2014 Jennifer A. Walker

Abstract

Effective management of grazing lands is important for longevity and productivity. Accurate calculations of stocking rates per animal unit will aid in long term sustainability. Calculating stocking rates for cattle can prove challenging for cows and nursing calves. Limited research has been conducted to determine forage intake of the nursing calf pre-weaning. The objective of Trial 1 was to determine nursing calf forage intake over time until weaning. Trial 1 used 8 crossbred cow-calf pairs in experiment 1 and 12 pairs in experiment 2. Pairs were separated into two groups rotating between grazing upland range or housed in individual pens separated by pair. Pairs were fed harvested meadow hay similar in quality to the rangeland. Hay, diet, and refusal samples were collected as well as total calf fecal collection. Organic matter intake (OMI) of nursing calves on pasture increased from 1.33-1.68% of BW and decreased to 1.43% in period 6. Pen OMI increased from 0.89-1.55% of BW and then decreased to 1.42% of BW also in period 6.There was no significant difference in OMI between Pasture and Pen for kg per day or as a percent of BW (P>.10). Determining the digestibility of forages is challenging and time consuming. Using in vitro techniques to evaluate feed digestibility can expedite the process. The use of forage samples as standards with known in vivo digestibility values is important for adjusting in vitro values. Trial 2 used 6 crossbred yearling steers in a switchback design to determine in vivo digestibility of two chopped hays (meadow and brome hay). The objective was to create two forage standards to use in in vitro laboratory procedures to estimate unknown in vivo digestibility of forages. Hays were evaluated for differences in digestibility and digestibility measured by three methods. Meadow and brome hays were found to be significantly different in digestibility (P<.0001). These hays can be used as part of a standard forage sample set to evaluate unknown samples for digestibility.

Advisors: Karla J. Jenkins and Terry J. Klopfenstein

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