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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 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  
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  Notes PMID:1317449 Approved no  
  Call Number refbase @ user @ Serial 145  
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Author Rutberg, A.T.; Keiper, R.R. url  doi
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  Title Proximate causes of natal dispersal in feral ponies: some sex differences Type Journal Article
  Year 1993 Publication Animal Behaviour. Abbreviated Journal Anim. Behav.  
  Volume 46 Issue 5 Pages 969-975  
  Keywords  
  Abstract Abstract. Fifteen years of data on natal dispersal age and the context of dispersal for the feral ponies of Assateague Island, Maryland are presented. Ninety-seven per cent of males and 81% of females dispersed from their natal groups by 5 years of age. For animals that left their natal group, average age of dispersal was 20[middle dot]8 months for males and 24[middle dot]6 months for females. Male dispersal age was strongly and significantly correlated with number of peers in the natal group, and males dispersing with peers were significantly older than males dispersing without peers, suggesting that males delayed dispersal when peers were available for interaction. Female dispersal age was not influenced by number of peers, but was correlated with age of first reproduction. Factors not influencing dispersal age in either sex were presence of a younger sibling, maternal band transfers, and maternal age and dominance rank. The relatively high frequency of females failing to disperse from their natal groups is puzzling in light of data showing diminished fecundity in non-dispersing pony mares.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 518  
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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 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  
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  Notes PMID:6732036 Approved no  
  Call Number refbase @ user @ Serial 665  
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Author Houpt, K.A.; Keiper, R. openurl 
  Title The position of the stallion in the equine dominance hierarchy of feral and domestic ponies. Type Journal Article
  Year 1982 Publication Journal of Animal Science Abbreviated Journal J. Anim Sci  
  Volume 54 Issue 5 Pages 945-950  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 668  
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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 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  
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  Notes PMID:3492240 Approved no  
  Call Number refbase @ user @ Serial 675  
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Author Keiper, R.R.; Sambraus, H.H. url  doi
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  Title The stability of equine dominance hierarchies and the effects of kinship, proximity and foaling status on hierarchy rank Type Journal Article
  Year 1986 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 16 Issue 2 Pages 121-130  
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  Abstract Dominance hierarchies were determined in four bands of feral horses living on Assateague Island. The bands varied in size from 10 to 16 horses, and consisted of one stallion, several mares and their offspring. The animals ranged in age from less than 1 to over 18 years. Field observation of all social interactions during the summer of 1981 was used to determine dominance. 1981 hierarchies for three of the bands were compared with hierarchies determined for the same bands in 1978, and showed that hierarchies change over time. Age was significantly correlated with rank. Mares with foals did not rank any higher in the hierarchies than mares without foals. Kinship did not appear to have an effect on dominance rank either, since neither juvenile nor adult offspring ranks correlated with the ranks of their mothers. The band stallion was not the highest-ranking animal of any band, but the location of the stallion peripheral to the main body of the band, the nature of his interactions with band members, and his length of residence in the band may have contributed to his low rank.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 683  
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Author Keiper, R.R. url  doi
openurl 
  Title Social interactions of the Przewalski horse (Equus przewalskii Poliakov, 1881) herd at the Munich Zoo Type Journal Article
  Year 1988 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 21 Issue 1-2 Pages 89-97  
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  Abstract Data were collected on 972 aggressions and 233 acts of mutual grooming in a herd of 9 Przewalski horses in the Hellabrunn Tierpark in Munich, West Germany. The herd was composed of 1 adult stallion, 5 adult mares and 3 foals. A distinct linear dominance hierarchy was present in the herd, with the stallion being the top-ranking animal. Age was significantly correlated with rank. Almost 40% of all aggressions consisted of herding actions by the stallion. Threats to bite (20% of all aggressions) and threats to kick (11.4%) were next in frequency of occurrence. Most mutual grooms (71%) involved grooming the front part of the body. Although mutual grooming may be used to appease higher-ranked animals, most grooming bouts were between related horses. Foals initiate 47.6% of all allogrooming. Mutual grooming may reduce weaning conflict between a mare and her foal or may result in female coalitions that defend against predators or aggression by the herd stallion.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 775  
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Author Keiper, R.; Receveur, H. url  doi
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  Title Social interactions of free-ranging Przewalski horses in semi-reserves in the Netherlands Type Journal Article
  Year 1992 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.  
  Volume 33 Issue 4 Pages 303-318  
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  Abstract Social interactions were recorded in two bands of free-ranging Przewalski horses living on large (greater than 30 ha) pastures in the Netherlands. The average number of aggressive interactions per hour was 8.86 at Lelystad and 10.36 at Noorderheide. The most common aggressive interactions were lower intensity, lower cost displacements (17.2% of all aggressive acts at Lelystad, 13.2% at Noorderheide), threats to bite (42.3% and 40.7%, respectively) and threats to kick (15.4% and 23.9%, respectively). Analysis of aggression revealed that a clear, linear dominance hierarchy was present in each band. For each band there was a positive and highly significant correlation between the age of a horse and its rank in the hierarchy. In each band, the stallion was not the highest ranked horse. Non-agonistic behaviors exceeded the number of agonistic interactions (1253 vs. 558 for Lelystad; 1257 vs. 995 at Noorderheide). There was a negative correlation between the rank of a horse in the dominance hierarchy and the number of non-agonistic behaviors displayed. The group displaying the highest number of non-agonistic interactions were foals (48.9% of total non-agonistic behaviors at Lelystad; 51.1% at Noorderheide). The non-agonistic/agonistic ratio was greater than 1 for yearlings and the band stallion, as was also the case for foals, but was less than 1 for males.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 778  
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Author Keiper, R. openurl 
  Title Social organization of feral ponies Type Journal Article
  Year 1976 Publication Abbreviated Journal Proc Pennsyl Acad Sci  
  Volume 50 Issue Pages 69-70  
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  Notes from Professor Hans Klingels Equine Reference List Approved no  
  Call Number Serial 1250  
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Author Keiper, R.R.; Moss, M.; Zervanos, S. openurl 
  Title Daily and seasonal patterns of feral ponies on Assateague Island. Type Conference Article
  Year 1980 Publication 2nd Conference on Scientific Research in the National Parks Abbreviated Journal  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 2310  
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