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Author |
Lee, R.D. |
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Title  |
Rethinking the evolutionary theory of aging: transfers, not births, shape senescence in social species |
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Journal Article |
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Year |
2003 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc Natl Acad Sci U S A |
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Volume |
100 |
Issue |
16 |
Pages |
9637-9642 |
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Keywords |
Adaptation, Physiological; *Aging; Animals; *Biological Evolution; Demography; Economics; Environment; Fertility; Humans; Life Expectancy; Longevity; Models, Theoretical; Parturition; Population Dynamics; Population Growth; Reproduction |
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The classic evolutionary theory of aging explains why mortality rises with age: as individuals grow older, less lifetime fertility remains, so continued survival contributes less to reproductive fitness. However, successful reproduction often involves intergenerational transfers as well as fertility. In the formal theory offered here, age-specific selective pressure on mortality depends on a weighted average of remaining fertility (the classic effect) and remaining intergenerational transfers to be made to others. For species at the optimal quantity-investment tradeoff for offspring, only the transfer effect shapes mortality, explaining postreproductive survival and why juvenile mortality declines with age. It also explains the evolution of lower fertility, longer life, and increased investments in offspring. |
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Department of Demography, University of California, 2232 Piedmont Avenue, Berkeley, CA 94720-2120, USA. rlee@demog.berkeley.edu |
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0027-8424 |
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PMID:12878733 |
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Equine Behaviour @ team @ |
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5465 |
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Author |
Arnold, W.; Ruf, T.; Kuntz, R. |
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Title |
Seasonal adjustment of energy budget in a large wild mammal, the Przewalski horse (Equus ferus przewalskii) II. Energy expenditure |
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Journal Article |
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Year |
2006 |
Publication |
The Journal of experimental biology |
Abbreviated Journal |
J Exp Biol |
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Volume |
209 |
Issue |
Pt 22 |
Pages |
4566-4573 |
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Animals; Animals, Wild/*physiology; Body Temperature; Body Temperature Regulation; Eating; *Energy Metabolism; Female; Heart Rate; Horses/*physiology; Male; Motor Activity; Pregnancy; Reproduction; *Seasons |
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Many large mammals show pronounced seasonal fluctuations of metabolic rate (MR). It has been argued, based on studies in ruminants, that this variation merely results from different levels of locomotor activity (LA), and heat increment of feeding (HI). However, a recent study in red deer (Cervus elaphus) identified a previously unknown mechanism in ungulates--nocturnal hypometabolism--that contributed significantly to reduced energy expenditure, mainly during late winter. The relative contribution of these different mechanisms to seasonal adjustments of MR is still unknown, however. Therefore, in the study presented here we quantified for the first time the independent contribution of thermoregulation, LA and HI to heart rate (f(H)) as a measure of MR in a free-roaming large ungulate, the Przewalski horse or Takhi (Equus ferus przewalskii Poljakow). f(H) varied periodically throughout the year with a twofold increase from a mean of 44 beats min(-1) during December and January to a spring peak of 89 beats min(-1) at the beginning of May. LA increased from 23% per day during December and January to a mean level of 53% per day during May, and declined again thereafter. Daily mean subcutaneous body temperature (T(s)) declined continuously during winter and reached a nadir at the beginning of April (annual range was 5.8 degrees C), well after the annual low of air temperature and LA. Lower T(s) during winter contributed considerably to the reduction in f(H). In addition to thermoregulation, f(H) was affected by reproduction, LA, HI and unexplained seasonal variation, presumably reflecting to some degree changes in organ mass. The observed phase relations of seasonal changes indicate that energy expenditure was not a consequence of energy uptake but is under endogenous control, preparing the organism well in advance of seasonal energetic demands. |
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Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Savoyenstrasse 1, 1160 Vienna, Austria. walter.arnold@vu-wien.ac.at |
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0022-0949 |
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PMID:17079726 |
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1782 |
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Franceschini, C.; Siutz, C.; Palme, R.; Millesi, E. |
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Seasonal changes in cortisol and progesterone secretion in Common hamsters |
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Journal Article |
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Year |
2007 |
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General and Comparative Endocrinology |
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Gen Comp Endocrinol |
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152 |
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1 |
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14-21 |
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Animals; Cortisone/*secretion; Cricetinae/*metabolism; Feces/chemistry; Female; Lactation/physiology; Male; Pregnancy; Progesterone/*secretion; Reproduction/physiology; *Seasons; Sexual Behavior, Animal/physiology |
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In this study, we investigated endocrine factors and behaviour in free-living Common hamsters (Cricetus cricetus) during reproductive and non-reproductive periods of the annual cycle. We applied a non-invasive method to gain information on seasonal changes in adrenocortical activity in male and female hamsters by analysing faecal glucocorticoid metabolite concentrations (FCM). In addition, plasma progesterone concentrations were monitored in females throughout the non-hibernation season. The animals were live-trapped from spring emergence until the onset of hibernation in autumn. Reproductive status was determined at capture and blood and faecal samples were collected. During behavioural observations, agonistic and sexual interactions were recorded. FCM concentrations were significantly higher in males than in females during the reproductive period. In males, a pronounced increase in FCM during the reproductive period coincided with high frequencies of intrasexual aggression. In females, FCM levels remained relatively constant. Aggressive behaviour in females increased during the reproductive period, but was much less frequent than in males. Females, which successfully raised a second litter after a postpartum oestrus and concurrent lactation and gestation had lower FCM levels than individuals, which lost their second litter after parturition. As expected, plasma progesterone concentrations were low before and after the reproductive period. During gestation, levels peaked and remained elevated during lactation. The results of this field study provide insight in critical periods associated with reproduction in male and female Common hamsters. |
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Department of Behavioural Biology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria. claudia.franceschini@univie.ac.ct |
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0016-6480 |
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PMID:17408667 |
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Equine Behaviour @ team @ |
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4076 |
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Ben-Shahar, R |
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Selectivity in large generalist herbivores: feeding patterns of African ungulates in a semi-arid habitat |
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1991 |
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African Journal of Ecology |
Abbreviated Journal |
Afr. J. Ecol. |
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29 |
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4 |
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302-315 |
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diet; forage production; grazing; wildebeest; zebra |
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Feeding habits of free-ranging wildebeest and zebra were monitored in a semi-arid nature reserve, bordering the southwestern part of Kruger National Park, South Africa. The purpose of study was to distinguish and define the feeding niches of two roughage grazers that occur in similar habitat types. The monthly compositions of diets were evaluated by direct observations of feeding bouts over a period of two years when rainfall patterns were average and animal populations were stable. Other analyses evaluated the standing biomass of grass species in the reserve during the wet summer and dry winter seasons.
A considerable overlap of grass species composition was found in the diets of wildebeest and zebra. Ordination of bi-monthly records of the diet composition showed greater variations in scores of grasses in zebra diet in comparison to wildebeest. Seasonal patterns were more apparent in the wildebeest diet. Preference ranking of grass species indicated that zebra diet remained constant in winter and summer. Wildebeest diet however, alternated with seasons, showing high preferences during the winter months for grass species which were rejected during summer.
The combined assessment of results from three separate statistical methods analysing temporal patterns and preferences in diet composition revealed contradictory trends. The solution, however, relied on the initial assumptions posed. Hence, wildebeest and zebra are essentially generalist feeders which show a limited amount of preference in their choice of diet. |
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Equine Behaviour @ team @ |
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2226 |
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Author |
Klingel, H. |
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Title |
Social organization and reproduction in equids |
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Journal Article |
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1975 |
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Journal of Reproduction and Fertility. Supplement |
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J Reprod Fertil Suppl |
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23 |
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7-11 |
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Animals; Behavior, Animal; Female; Male; Perissodactyla/*physiology; Reproduction; *Sexual Behavior, Animal; Social Behavior; Territoriality |
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There are two distinct types of social organization and, accordingly, two types of mating systems in equids. In the horse, Plains zebra and Mountain zebra, the adults live in non-territorial and cohesive one-male groups and in stallion groups. The family stallions have exclusive mating rights which are respected by all others. In Grevy's zebra and in the African and Asiatic wild asses, the stallions are permanently territorial and have exclusive mating rights within their territories. Ecological and evolutionary aspects are discussed. |
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0449-3087 |
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PMID:1060868 |
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Equine Behaviour @ team @ |
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2303 |
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Palme, R.; Touma, C.; Arias, N., Dominchin, M.N.; Lepschy, M. |
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Title |
Steroid extraction: Get the best out of faecal samples |
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Journal Article |
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2013 |
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Wiener Tierärztliche Wochenschriften |
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Wien Tierärztl Monat – Vet Med Austria |
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100 |
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238-246. |
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Review, faeces, extraction, non-invasive hormone monitoring, stress, reproduction. |
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Faecal steroid hormone metabolites are becoming increasingly popular as parameters for reproductive functions and stress. The extraction of the steroids from the faecal matrix represents the initial step before quantification can be performed. The steroid metabolites present in the faecal matrix are of varying polarity and composition, so selection of a proper extraction procedure is essential. There have been some studies to address this complex but often neglected point. Radiolabelled steroids (e.g. cortisol or progesterone) have frequently been added to faecal samples to estimate the efficiency of the extraction procedures used. However, native, unmetabolized steroids are normally not present in the faeces and therefore the results are artifi- cial and do not accurately reflect the actual recoveries of the substances of interest. In this respect, recovery experiments based on faecal samples from radiometabolism studies are more informative. In these samples, the metabolite content accurately reflects the mixture of metabolites present in the given species. As a result, it is possible to evaluate different extraction methods for use with faecal samples. We present studies on sheep, horses, pigs, hares and dogs that utilized samples containing naturally metabolized, 14C-labelled steroids. We recommend extracting faecal steroids by simply suspending the faeces in a high percentage of a primary alcohol (for glucocorticoid metabolites 80% aqueous methanol proved best suited for virtually all mammalian species tested so far). Not only does the procedure significantly increase the total amount of recovered radioactivity, it also increases the percentage of unconjugated metabolites, which are more likely to be recognized by the antibodies used in various immunoassays. The advantages of this extraction procedure are clear: it is very easy to use (no evaporation step is needed), it yields high recoveries and variation based on the extraction procedure is reduced to a minimum. |
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Equine Behaviour @ team @ |
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6520 |
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Chenoweth, P.J.; Chase, C.C.; Larsen, R.E.; Thatcher, M.-J.D.; Bivens, J.F.; Wilcox, C.J. |
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The assessment of sexual performance in young Bos taurus and Bos indicus beef bulls |
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Journal Article |
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1996 |
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Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
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48 |
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3-4 |
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225-235 |
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Bos indicus; Sex behavior; Cattle reproduction; Mating behavior; Tests |
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Yearling beef bulls, representing different Bos indicus and Bos taurus breeds, were given two sexual performance assessments (libido score, number of services, time to first mount and time of sexual inactivity) at four test periods (January, April, July and October) in 1991 (Trial 1) and 1992 (Trial 2) at the Subtropical Agricultural Research Station, Brooksville, Florida. Breed and test period, as well as their interactions, influenced most results. Sexual performance assessments generally improved with age in Bos taurus breeds, but not in Bos indicus. The temperate Bos taurus breeds (Angus and Hereford) were most sexually active, the tropically adapted Bos taurus breeds (Senepol and Romosinuano) intermediate and the two Bos indicus breeds (Brahman and Nellore x Brahman) were least active. Service rates were generally low. Seasonal patterns in sexual performance were not apparent, with breed and year differences occurring. Although breeds showed consistent test results, the failure of Bos indicus bulls to service in any test, indicates either sexual immaturity, or inadequate procedures for assessment of sexual performance in this breed group. |
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refbase @ user @ |
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2865 |
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Breuer, K.; Hemsworth, P.H.; Coleman, G.J. |
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The effect of positive or negative handling on the behavioural and physiological responses of nonlactating heifers |
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Journal Article |
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2003 |
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Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
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84 |
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1 |
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3-22 |
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Dairy heifer; Fear; Handling; Stress response; Milk production; Stimulus generalisation |
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This experiment investigated the effects of positive and negative tactile handling on the stress physiology and behaviour of dairy heifers. Forty-eight 5-14-month-old nonlactating Holstein-Friesian heifers were allocated to one of two handling treatments, either positive or negative tactile handling, over four time replicates. Handling was imposed twice daily, 2-5 min per session and involved moving animals individually along a 64 m outdoor route. The negatively handled heifers took longer to approach within 1 and 2 m of a stimulus person in a standard test, than their positively handled counterparts (P<0.001) and had a greater flight distance to an approaching stimulus (P<0.001). The time taken by the heifers to approach within 1 and 2 m of a familiar person was similar to that taken to approach within 1 and 2 m of an unfamiliar person in the standard test (P<0.05). There was a tendency for heifers to have a greater flight distance from the approaching unfamiliar person than from the approaching familiar person (P=0.06). The negatively handled heifers had greater (P<0.05) increases in total cortisol concentrations 5, 10 and 15 min after exposure to a human and had higher (P<0.05) free cortisol concentrations in the afternoon than the positively handled heifers. It is concluded that the nature of the human contact affects the subsequent behavioural response of heifers to humans. This behavioural response may extend to other humans through the process of stimulus generalisation, although there was some evidence of moderate discrimination. Negative handling results in an acute stress response in the presence of humans and also leads to a chronic stress response. Further research into the effect of these stress responses on milk production and welfare in fearful cows in a commercial situation is suggested. |
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0168-1591 |
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Equine Behaviour @ team @ |
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4980 |
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Bermudez, J.L. |
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The moral significance of birth |
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1996 |
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Ethics |
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Ethics |
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106 |
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2 |
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378-403 |
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Abortion, Induced; Animal Rights; Animals; Beginning of Human Life; Embryonic and Fetal Development; *Ethical Analysis; *Ethics; *Fetus; Homicide; Humans; *Individuality; *Infant, Newborn; Infant, Premature; Infanticide; *Labor, Obstetric; Life; *Personhood; Philosophy; Primates; Psychology; *Self Concept; *Value of Life; Analytical Approach; Genetics and Reproduction; Philosophical Approach |
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0014-1704 |
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PMID:11656645; KIE: 31 fn.; KIE: KIE BoB Subject Heading: fetuses; KIE: KIE BoB Subject Heading: personhood |
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Equine Behaviour @ team @ |
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4177 |
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Ogbourne, C.P. |
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Variations in the fecundity of strongylid worms of the horse |
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1971 |
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Parasitology |
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Parasitology |
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63 |
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2 |
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289-298 |
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Animals; Animals, Newborn; Ecology; Feces; Female; Horses; Larva/growth & development; Male; Ovum; Parasite Egg Count; Reproduction; Seasons; Strongyle Infections, Equine/*etiology; Strongyloides/*growth & development; Time Factors |
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0031-1820 |
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PMID:5129804 |
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Equine Behaviour @ team @ |
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2727 |
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