Doctoral Dissertations

Date of Award

8-1979

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

J. B. McLaren

Committee Members

W. T. Butts, V. H. Reich, D. O. Richardson, R. R. Shrode, P. C. Smith

Abstract

The objectives of this study were to determine effects of year, breed, farm of origin, feeder-calf grade, and calf size and shape indexes on market-transit shrink, feedlot performance, morbidity patterns, and carcass traits of stressed feeder steers. Indexes of calf size and shape were the result of principal-component analysis.

The data were obtained on 458 steer calves, weighing 137 to 296 kg, purchased in the falls of 1976 and 1977 from 21 Tennessee farms of origin. Thirty days prior to marketing, all calves were weighed and measured at the farm of origin. The body measurements taken were height, length, depth, width, and back fat over the 12th rib. These weights and body measurements were used in a principal-component analysis to determine weighting factors for calculating individual calf size and shape indexes.

Each year all calves were transported 40 to 100 km on the same day to the auction barn where purchase weights were taken. Feeder-calf grades were assigned by 2 Tennessee State Department of Agriculture feeder-calf graders. During the first 24 hr in the barn, auction-barn burn environment was duplicated by keeping calves in close confinement without feed and water. Calves were reweighed at the end of the auction barn phase. Order-buyer-barn environment was duplicated during the last 72 hrs in the barn by allowing steers 1.8 to 2.3 m2 each access to feed and water. After the order-buyer-barn phase, the calves were weighed and transported by truck 1,600 km to the USDA Southwestern Great Plains Research Center at Bushland, Texas.

Immediately after unloading at the feedlot, calves were weighed, branded, and assigned to pens. All calves were given free access to a 50%-concentrate starter diet. In addition, grass hay was provided at a level of .9 kg/steer/day for two days. One-half of the pens received a B-vitamin supplement in the starter ration for the first 14 days post arrival. On feedlot day 15, the ration was changed to a 75%-concentrate ration, and on feedlot day 25, the ration was changed to a 90%-concentrate finishing ration.

Farm of origin was a major factor affecting (P< .01) market-transit weight change and post-transit performance. Percentage of calves sick ranged from 19.6 in calves from farm 13 to 87.1 in calves from farm 3. Large-framed, heavy calves lost more (P< .01) weight in the auction barn and during the total market-transit scheme, but had a smaller percentage sick, were sick fewer total days, had a lower effective sickness index, and gained faster in the feedlot than small-framed, light calves. Tall, thin calves lost more weight in market-transit, were sick longer, and had a higher effective sickness index, but gained faster in the feedlot, than short, fat calves. Angus (A) calves had a lower percentage sick (33.8) and effective sickness index (2.11) than Hereford (H) (70.1 and 5.82, respectively) and crossbred calves other than A-H (55.7 and 4.53, respectively). Good-grade steers gained more weight than prime-, choice-, or X-grade steers in the order-buyer-barn and at all phases in the feedlot. The prime steers tended to have a higher percentage sick. The grading system used by the Tennessee State Department of Agriculture separated the calves into groups by frame size and thickness. Calves shipped in 1977 lost more (P< .01) weight in the auction barn and during the total market-transit scheme but gained more in the order-buyer-barn than those shipped in 1976, the mean weight changes (kg) being -16.38, -27,42, 6.48, and -10.99, -22.69, 4.50 in 1977 and 1976, respectively.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS