Document Detail

Effects of nutritional environment and ram effect on breeding season in range sheep.
MedLine Citation:
PMID:  16726123     Owner:  NLM     Status:  In-Data-Review    
Effects of season, nutritional environment, and presence of rams on incidence and rate of ovulation in fine-wool sheep in southern New Mexico were investigated over 14 months (February 1983-March 1984). Number of corpora lutea (CL) were observed each month by laparoscopy in random samples from six ewes in each subgroup. Seasonality of ovulation in fine-wool sheep managed on range was much more marked than in animals managed on alfalfa hay in drylot. Incidence of ovulation approached zero in range-managed ewes during May, June, and July (8%, 0%, 4%) but was higher (P<0.05) in the alfalfa-drylot group (42%, 17%, 75%), respectively. Although the incidence remained lower (P<0.05) in August in range-managed than in drylot ewes (50% and 83%, respectively), both groups were ovulating at a high rate during September through January. Incidence of ovulation dropped dramatically both years in the range-managed group in February compared with that of the alfalfa-drylot group (48% and 36% vs 100% and 83%). Mean ovulation rate per ewe ovulating did not differ (P>0.10) between nutrition groups within the 14 months. Body weight was related to CL number during periods of seasonal transition only. Continuous or intermittent presence of a ram had no real effect on either incidence or rate of ovulation during the transitional months. Nutritional environment can affect seasonality of breeding in fine-wool range sheep. This effect may not be consistently modified by presence of rams.
C V Hulet; W L Shupe; T Ross; W Richards
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Theriogenology     Volume:  25     ISSN:  0093-691X     ISO Abbreviation:  Theriogenology     Publication Date:  1986 Feb 
Date Detail:
Created Date:  2006-05-26     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0421510     Medline TA:  Theriogenology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  317-23     Citation Subset:  -    
U.S. Department of Agriculture, Agricultural Research Service, Jornada Experimental Range, Las Crusces, NM 88003 USA.
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