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Author Keiper, R.; Houpt, K. openurl 
  Title Reproduction in feral horses: an eight-year study Type Journal Article
  Year 1984 Publication American journal of veterinary research Abbreviated Journal Am J Vet Res  
  Volume 45 Issue 5 Pages 991-995  
  Keywords (up) Abortion, Veterinary/epidemiology; Anestrus; Animal Population Groups/*physiology; Animals; Animals, Wild/*physiology; Birth Rate; Female; Fertility; Horse Diseases/epidemiology; Horses/*physiology; Lactation; Male; Maryland; Pregnancy; *Reproduction; Seasons; Sex Ratio; Virginia  
  Abstract The reproductive rate and foal survival of the free-ranging ponies on Assateague Island National Seashore were studied for 8 years, 1975 to 1982. Most (52%) of the 86 foals were born in May, 13% were born in April, 22.6% in June, 10.4% in July, and less than 1% in August and September. The mean foaling rate was 57.1 +/- 3.9% and the survival rate was 88.3 +/- 3.6%. Forty-eight colts and 55 fillies were born (sex ratio 53% female). Mares less than 3 years old did not foal and the foaling rate of 3-year-old mares was only 23%, that of 4-year-old mares was 46%, that of 5-year-old mares was 53%, and 6-year-old mares was 69%. The relatively poor reproduction rate was believed to be a consequence of the stress of lactating while carrying a foal when forage quality on the island was low. The hypothesis was supported by the higher reproductive rate (74.4 +/- 2.4%) of the ponies in the Chincoteague National Wildlife Refuge on the southern part of the island. Their foals are weaned and sold in July each year. Despite the low reproductive rate on Assateague Island National Seashore , the number of ponies increased from 43 to 80, a 90% increase in the 8-year period or greater than 10%/yr. There were 24 deaths and 8 dispersals from the study area.  
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  ISSN 0002-9645 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:6732036 Approved no  
  Call Number refbase @ user @ Serial 665  
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Author BASHORE, T. L.; KEIPER, R.; TURNER ,J. W. JR; KIRKPATRICK J. F. url  openurl
  Title The accuracy of fixed-wing aerial surveys of feral horses on a coastal barrier island Type Journal Article
  Year 1990 Publication Journal of coastal research Abbreviated Journal J. coast. res  
  Volume 6 Issue Pages 53-56  
  Keywords (up) Accuracy; Airborne methods; Vegetation; Barrier islands; Maryland; Ground methods; United States; North America; America  
  Abstract  
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  Series Volume Series Issue Edition  
  ISSN 0749-0208 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 2221  
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Author Keiper, R.R. openurl 
  Title Social structure Type Journal Article
  Year 1986 Publication The Veterinary clinics of North America. Equine practice Abbreviated Journal Vet Clin North Am Equine Pract  
  Volume 2 Issue 3 Pages 465-484  
  Keywords (up) Animal Communication; Animals; Animals, Domestic; Animals, Wild; Dominance-Subordination; Female; *Hierarchy, Social; Homing Behavior; *Horses; Male; Sexual Behavior, Animal; *Social Behavior; *Social Dominance  
  Abstract Socially feral horses live in stable social groups characterized by one adult male, a number of adult females, and their offspring up to 2 years of age. Extra males either live by themselves or with other males in bachelor groups. The bands occupy nondefended home ranges that often overlap. Many abnormal behaviors seen in domestic horses occur because some aspect of their normal social behavior cannot be carried out in captivity.  
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  ISSN 0749-0739 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:3492240 Approved no  
  Call Number refbase @ user @ Serial 675  
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Author Kirkpatrick, J.F.; Liu, I.M.; Turner, J.W.J.; Naugle, R.; Keiper, R. openurl 
  Title Long-term effects of porcine zonae pellucidae immunocontraception on ovarian function in feral horses (Equus caballus) Type Journal Article
  Year 1992 Publication Journal of reproduction and fertility Abbreviated Journal J Reprod Fertil  
  Volume 94 Issue 2 Pages 437-444  
  Keywords (up) Animals; Contraception, Immunologic/*veterinary; *Egg Proteins; Estrogens, Conjugated (USP)/urine; Female; Glycoproteins/*pharmacology; Horses/immunology/*physiology; *Membrane Glycoproteins; Ovary/drug effects/*physiology; Progesterone/metabolism; *Receptors, Cell Surface; Swine/immunology; Time Factors; Zona Pellucida/*immunology  
  Abstract Ten feral mares free-roaming in Maryland, USA, were inoculated with porcine zonae pellucidae (PZP) protein before the breeding season for three consecutive years (1988-90). Ovarian function was monitored for 51 days during the peak of the breeding season after the third annual PZP inoculation, in seven of these mares and in four untreated control mares, by means of urinary oestrone conjugates and nonspecific progesterone metabolites. None of the ten inoculated mares became pregnant in 1990, compared with 55% of 20 control mares, which included two of the four monitored for ovarian function. Three of the untreated mares demonstrated apparent normal ovarian activity, characterized by preovulatory oestrogen peaks, concurrent progesterone nadirs at ovulation, breeding activity, and luteal-phase progesterone increases after ovulation. Two of the seven monitored PZP-treated mares demonstrated ovulatory cycles that did not result in conception. One was pregnant as a result of conception in 1989 and demonstrated a normal, late-gestation, endocrine profile. The remaining four PZP-treated mares revealed no evidence of ovulation, and urinary oestrogen concentrations were significantly depressed. The experiments indicated that (i) a third consecutive annual PZP booster inoculation is greater than 90% effective in preventing pregnancies in mares and (ii) three consecutive years of PZP treatment may interfere with normal ovarian function as shown by markedly depressed oestrogen secretion.  
  Address Deaconess Research Institute, Billings, MT 59102  
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  ISSN 0022-4251 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:1317449 Approved no  
  Call Number refbase @ user @ Serial 145  
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