Improved Forage/Sheep Production Efficiency
Project Number: 1932-13310-001-02S
Researchers: Turner, K. E.; Belesky, D. P.; Lewis, P.
Start Date: 01-Sep-89
End Date: 30-Jun-94
Performing Institution: Agricultural Research Service and West Virginia University, Morgantown, WV 26506
Research Objectives: Develop strategies to synchronize lambing
and forage availability/quality with nutrient requirements of sheep in a manner to produce quality lamb products year-round.
Approach: Switchgrass will be grazed under different management regimes to determine forage quality, productivity, and persistence. A metabolism trial will be concurrently conducted to determine intake, digestibility, and nutritional quality of switchgrass. Ultrasonic methodology will be developed to assess carcass quality. Determine effects of season, breed, ram management, hormonal therapy, body condition, and nutritional management on fecundity of ewes enduced to breed during anestrus.
Progress: Cooperative studies with WVU on summer grazing systems for sheep production, body composition, and reproductive performance have been completed. Sheep grazing switchgrass forage this year showed no signs of photosensitization. Further analyses are being conducted to screen forage samples for potentially toxic compounds.
Data collected using ultrasonographic imaging, urea dilution space, and rack composition as predictors of carcass composition are being evaluated. Reproductive physiology studies to monitor effects of follicle stimulating hormone (FSH) and ram introduction on ewe fertility and lambing rate have been completed. Lambing rate was increased in FSH-treated vs control ewes, but lambing rate in ewes with high ovulation rates was equal to FSH-treated and control groups.
In addition, effects of progesterone on follicular growth and subsequent fertility in ewes were evaluated. Administration of low levels of progesterone increased size of the largest ovary and age of the oldest ovulatory follicles. High concentrations of estadiol may results in early loss of pregnancy.
1. POLAND, W., REID, R.L. and TURNER, K.E. 1993. Effect of transducer frequency and image magnification on sources of variation in ultrasonographic measurements. J. Anim. Sci. Abstr. 71:149
2. L., POLAND K., and TURNER, K.E. 1993. Procedural sources of variation in ultrasonographic estimates of lamb carcass measurements. J. Dairy Sci. Abstr. 76:236.