INTRODUCTION
 The Beef Research Unit of the Florida Agricultural Experi-
ment Station was established near Gainesville during 1951 and
1952. The first undertaking at this unit was a long-term project
to investigate "Pasture Programs and Cattle Breeding Systems
for Beef Production in North Central Florida." The project was
an interdisciplinary undertaking involving the joint efforts of
five departments: Agricultural Engineering, Agronomy, Animal
Science, Food and Resource Economics, and Soils. The project
was governed by a coordinating committee including one or more
research specialists and an administrator from each of the five
departments.
 Pasture programs were evaluated by grazing with cows and
calves in a systems approach including all components of the
beef production system so that the data could be applied to com-
mercial cattle production. The animals used to evaluate the pas-
ture programs were utilized also to compare five alternative
mating systems for commercial beef production and to observe
the differential response of these groups to the different pasture
programs. Representative animals from each of the mating
groups were used in a balanced design annually to graze each of
the pasture programs.
 The project was conducted in three phases and spanned 21
years from 1952 to 1972. Different sets of pasture programs were
compared during the three phases. Data from the pasture pro-
grams evaluated during the first two phases were presented pre-
viously in Florida Agricultural Experiment Stations Bulletins
(technical) 631 and 740. However, data on comparative perfor-
mance of cattle in the different mating systems have not been
presented previously.
 The objectives for this bulletin were (1) to report the data
from the three pasture programs compared during the last
(third) phase of the project, (2) to present the comparative per-
formance of cattle from the five mating systems tested, and (3)
to present an overall evaluation of results obtained over the en-
tire 21 years of the project. Detailed information on methods and
experimental procedures utilized are presented in the sections
by the departments. These departmental sections, along with the
two bulletins published previously, were reviewed to prepare the
21-year summary included as the last section of this bulletin.