Recent areas of interest have included the evaluation of sexual behavior of rams and the influence of the environment on the sexual behavior.  Other aspects of male physiology that have been studied include semen quality during the breeding season when rams are exposed to either synchronized or naturally cycling ewes.  There has also been some work done on evaluating the effects of immunizing ram lambs against inhibin on pubertal development and testis function.

     On the female side, the milk production and lamb growth of three breeds of sheep has  been evaluated.  There have been several projects conducted to evaluate the efficacy of various methods to synchronize estrus in hair sheep ewes.  The results of these studies were used in the development of methods for estrous synchronization and transcervical artificial insemination (TAI) of hair sheep ewes.  Recently TAI has been used to produce crossbred lambs by using semen from wool breeds on hair sheep ewes.  The lambs produced by these matings will be used to further evaluate the growth and carcass traits of hair and crossbred lambs under tropical conditions.  The increased size of the crossbred lambs has the potential to produce larger carcasses with lower input of costly resources, such as feed.  In addition to the growth of these lambs, the physiology and adaptation to the tropical environment of the hair sheep lambs will also be evaluated in comparison to that of the crossbred lambs.  One area of interest is a comparison of the parasite resistance between the two breed types.

    Currently a project is being developed to evaluate the parasite resistance/tolerance of hair sheep in comparison to wool crosses.  Management of parasites is one of the biggest concerns of sheep producers in the region.  The warm, humid climate is highly favorable to the life cycle of many sheep parasites.  Strategic use of anthelmintics has been used to control internal parasites, and further work is being done to evaluate these controls.

     Another ongoing project is evaluating the effect of supplemental feed on ewe performance.  Ewes are being supplemented at either breeding or lambing.  In the ewes being supplemented at lambing, lamb growth and ewe milk production are being measured.  Ovulation rate and conception are being evaluated in the ewes being fed around the time of breeding.  Because of the seasonal variation in forage availability during the year on St. Croix, each portion of the study is being conducted during both the rainy and the dry season.

     Recently three Dorper rams were purchased to conduct crossbreeding trials.  The Dorper breed was developed in South Africa and is a hair sheep breed that should be able to adapt to the tropical climate found on St. Croix better than the wool breeds used in previous crossbreeding trials. These rams were bred to the St. Croix White sheep and the growth and carcass traits of the crossbred offspring will be evaluated.   The first crop of Dorper-sired lambs were born in November 2001.  During 2002, crossbred lambs were used in a TSTAR-funded feeding trial to evaluate their performance in comparison to St. Croix White lambs.  The results of the trial showed that the Dorper crossbred lambs could have a positive impact on sheep production.  For a PowerPoint slide show of the results click here.  Subsequent trials are being conducted with lambs grazing native pasture during the dry and wet seasons.  The dry season grazing began in February 2003 and the wet season grazing will begin in September 2003.

     A crossbred flock will be established to evaluate the production traits of Dorper X St. Croix White ewes under tropical conditions.  Ewes will be managed in an extensive system, with rotational grazing and an accelerated lambing cycle.  Results will be posted to this page as they become available.