SCHOOL'S AGRICULTURE STUDY SHOWS IMPLANTS ENHANCE GROWTH OF CALVES

Results of a study conducted recently by the Department of Agriculture at Southeast Missouri State University show that implanting growth promotants in beef suckling calves enhances their growth.

The research was a joint effort of Southeast Missouri State University, S & S Livestock Supply and Syntex Laboratories, Inc.

Dr. William W. Ellis, Southeast professor of agriculture, designed and conducted the trial. Implanting was conducted by Sean Gray of S & S Livestock Supply, and implants were furnished by Syntex.

The study was conducted at the Southeast Missouri State University Demonstration Farm on beef calves born last spring. The goal of the study was to determine if suckling calves that had received implants displayed a higher growth rate than calves that had not received such implants.

"There is much evidence to support that implanting is a positive management decision for beef producers," Ellis said. "Essentially all studies demonstrate that implanted calves grow faster. The Southeast study was no exception."

Under the study, a group of calves at an average age of 36 days old were given implants of Synovex C 100 milligrams of progesterone and 10 milligrams of estradiol benzoate. Weight results showed they were 27 pounds heavier 120 days after the implants were administered than a group not receiving implants, Ellis said.

The study also tested the implanted calves to determine if they lost their growth advantage when the implant's life expired.

"There are some who feel the growth that results from implanting is due to water retention," Ellis said. "When the influence of the implant upon growth concludes, the implanted calf loses the water. Thus, these calves lose the weight gain from the implant."

To make the determination, a secondary phase of the study was conducted in which the calves previously implanted were divided in half. Half the calves were not given a second implant. The other half received a second implant of either Synovex H or S. Synovex H is for heifers and consists of 200 milligrams of progesterone and 20 milligrams of testosterone propionate. Synovex S is for steers and consists of 200 milligrams of progesterone and 20 milligrams estradiol benzoate.

Thus, the second phase of the study consisted of three groups: the original control group that received no implants, a group that received one implant, and group that received two implants, Ellis said. The three study groups were managed together.

Next, the calves were returned to their mothers and weaned six weeks later. Following weaning, the calves were placed in dry lot for 14 days.

The three groups then were moved to a combination fescue and legume pasture that had been used for harvesting hay and had not been grazed during 1991, Ellis said. The calves remained on the pasture for 120 days and then were weighed again. The 120-day pasture stay was to coincide with the effective release life of the second implant given the one group.

Weight results showed that the calves that received the initial implant did not lose their growth advantage during the second phase of the study, Ellis said. The test showed that the calves that had received the first implant were 34 pounds heavier than the original control group that were not implanted, he said.

"The 34-pound advantage demonstrates that the calves maintained their 27-pound advantage at 120 days and gained an additional seven," Ellis said.

The seven pounds can be explained in two ways, he added.

"Initially, not all calves absorb the implant at the same rate," Ellis said. "Thus some growth influence carryover remained from the first implant. Secondly, these calves were slightly larger as a result of the first implant. Because of this small size benefit, they could consume slightly more forage."

The study also proved that the second implant was beneficial, with those calves demonstrating considerable response.

"At the conclusion of the test, they were 42 pounds heavier than those calves that had received no implants and 14 pounds heavier than the calves that received only one implant," Ellis said.

"The data suggests that the management practice of implanting suckling calves with growth promotants will yield additional growth," he said. "The study also shows that this growth advantage was not lost after the period of implant effectiveness and suggests that growth benefits can be continued with a second implant."

For more information, contact Ellis at (314) 651-2797.