Date of Award
Master of Science
C. C. Chamberlain
J. B. McLaren, R. L. Murphree
The three objectives in this investigation were to (1) determine the effects of the four stages of maturity on silage yields and losses; (2) to evaluate both a visual method of silage scoring and chemical analysis; and (3) to determine the effects of corn silage harvested at four stages of maturity (late milk, early dough, late dough, and mealy endosperm) on the performance of feeder heifers. Theoretical green chop yield had a tendency to decrease as matu-rity increased. The tonnage of green chop ensiled was similar for the first three stages of maturity and higher than for the fourth stage. Expressed either as a percent of the theoretical yield or as dry matter per acre, the quantity of green chop ensiled increased through the third stage. Edible silage expressed as tons of dry matter per acre, increased through the third cutting. Losses between the theoretical values and the quantity ensiled were lower for the two middle stages of maturity as were the unaccountable losses between the time of en-siling and the actual quantity fed. Total visual score was closely associated with animal perform-ance with the second and third stages of maturity, but was not as good an indicator for the first and fourth stages of maturity. It was a good indicator of the daily air dry intake of silage by the animals. Individual components of the chemical analysis, on an "as fed" basis, had a tendency to increase with increasing maturity in the three year summary. Chemical analysis was not closely associated with animal performance. Animal performance showed yearly differences in silages which were not indicated by (1) chemical analysis, (2) by consumption on either an "as fed" or dry matter basis, or (3) the silage scores. Neither could the differences be explained by the digestibility studies conducted on the same silages by Prigge (1968). Average daily silage intake "as fed" decreased with increasing maturity, with the fourth stage of maturity being significantly less (P < .05) than the other three. However, in the three year summary expressed on an air dry basis, it was significantly higher (P < .05) for the middle stages of maturity than for the first and fourth stages. Average daily gains of the heifers during the silage phase for the late milk, early dough, and late dough stages were similar, but significantly higher (P < .05) than the gains obtained with the mealy endosperm stage. Pounds of feed required per pound of gain on an "as fed" basis had a tendency to decrease with increasing maturity. However, expressed on an air dry basis the trend reversed. No significant (P < .05) differences were found in (1) the live condition grades taken at the end of the silage phase, (2) the final live condition grades, and (3) the carcass characteristics obtained at the end of the full fed phase. Pounds of beef produced per acre of silage was highest for the late dough stage, and followed in decreasing order by the early dough, mealy endosperm, and late milk stages. In the full fed phase no significant (P < .05) differences were found in average daily gain or air dry matter intake indicating no "carry over" effects from the silage phase to the full fed phase.
Vickers, Robert T., "Effects of corn plant maturity at ensiling on the performance of feeder heifers. " Master's Thesis, University of Tennessee, 1971.