Masters Theses

Date of Award

8-1979

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Haley M. Jamison

Committee Members

William R. Backus, Don O. Richardson

Abstract

The data collected in this study were from 49 Hereford steers (Trial 1) and 75 Angus X Hereford steers (Trial 2). To simply the discussion, the 49 Hereford steers fed whole shelled corn for 114 days will be referred to as Analysis 1 and the 75 Angus X Hereford steers, of which 50 were fed whole shelled corn 78 days and the remaining 25 for 105 days, hereafter referred to as Analysis 2, Previously, the variances in the two analyses were determined to be homogenous; thus, the data on the two groups of steers were pooled into one group here after referred to as Analysis 3. The treatments in this study were: (1) no implant, (2) implanting with 36 mg. of Ralgro on day 56 of a 150 day feeding trial, (3) implanting with 36 mg. of Ralgro on day 1 of a 150 day feeding trial, (4) implanting on day 1 and day 56, totaling 72 mg., of a 150 day feeding trial, (5) implanting 72 mg, on day 1 of a 150 day feeding trial. The variables average daily gain on hay, average daily gain on corn, feed conversion, carcass weight, fat thickness, kidney, pelvic and heart fat, yield grade, rib eye area, and carcass grade were subjected to a least squares regression analysis as dependent variables to detect differences between treatments. The independent variables in this study were treatment, replication and trial. Treatment had a significant (P < .05) effect on average daily gain on full feed and percent kidney, pelvic and heart fat in Analysis 3. Carcass grade showed significant effects (P < .05) of treatment In Analyses 2 and 3. Average daily gain on hay was significantly affected by treatment in Analysis 1. Analysis 3 showed that treatment 2 had the highest least squares mean for average daily gain on corn, 3.38 lbs./day. Treatment 2 was .09 lbs./day superior to treatment 3, .15 lbs./day superior to treatment 4, .25 lbs./day greater than treatment 5, and .39 lbs./day superior to treatment 1, the control group. Analysis 3 showed that treatment had a significant effect on kidney, pelvic, and heart fat. The least squares means by treatment for Analysis 3 showed that carcasses from treatments 2 and 5 had 2.46 percent kidney, pelvic and heart fat. Thus carcasses from those two treatment groups were .10 percent lower in fat than those in treatment 3, .14 percent lower than carcasses in treatment 4, and .24 percent lower in fat than carcasses from treatment 1. Carcass grades were significantly affected (P < .05) by treatment in Analyses 2 and 3. Significant differences among treatments were found in the orthogonal contrast of treatment 4 vs. treatment 5 in both Analyses 2 and 3. Treatments 2 and 5 had the highest least squares mean for carcass grade, 11.93 in Analysis 2. This was .73 units higher than treatments 1 and 3, and .93 units higher than treatment 4. Analysis 3 showed that treatment 2 had the highest least squares mean, 12.18. This was .08 units higher than treatment 5, .55 units higher than treatment 1, .67 units higher than treatment 3, and .79 units higher than treatment 4. Average daily gain on hay also showed a response to treatment in Analysis 1, Although these steers were on poor quality roughage and losing weight, treatment 5 showed an average daily gain of -0,28. This was .25 lbs,/day superior to treatment 2, .39 lbs./day over treatment 4, .44 lbs./day over treatment 1, and .68 lbs./day over treatment 3. The implanting of 72 milligrams of Ralgro lowered carcass grades in the treatment 4 group in Analysis 3, and improved average daily gain on hay in Analysis 1, compared to the 36 milligram levels. Reimplanting decreased carcass grades significantly in Analysis 3 (P < ,05); but had no effect on carcass weight, fat thickness, rib eye area, yield grade, average daily gain on hay, and average daily gain on corn as compared to the other implanted cattle. This research is in agreement with that of previous experiments with the exception of the lowering of carcass grades on the reimplanted group of steers. From these data one could conclude that implanting with a growth stimulant is of little value unless the gains are in excess of .75 lbs./day. Further these data indicate that implanting with 36 mg. of Ralgro at the beginning of full feed phase was most beneficial. Implanting with dosage levels could have some detrimental effects on carcass grades.

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

Share

COinS