|
|
Albentosa, M. J., Kjaer, J. B., & Nicol, C. J. (2003). Strain and age differences in behaviour, fear response and pecking tendency in laying hens. Br Poult Sci, 44(3), 333–344.
Abstract: 1. Behaviours associated with a high or low tendency to feather peck could be used as predictors of feather pecking behaviour in selective breeding programmes. This study investigated how strain and age at testing influenced responses in behavioural tests. 2. Four layer-type strains (ISA Brown, Columbian Blacktail, Ixworth and a high feather pecking (HP) and a low feather pecking (LP) line of White Leghorn) were reared in 6 same-strain/line pens of 8 birds from one day old. Birds in half the pens were given an open field test, a novel object test and a test with loose feather bundles between 4 and 12 weeks of age and a tonic immobility (TI) test at 13 weeks of age. All pens were tested with fixed feather bundles at 26 weeks, and undisturbed behaviour in the home pens was videoed at 1 and 27 weeks of age. Daily records of plumage damage were used as an indicator of feather pecking activity in the home pens. 3. Strain did not influence novel object test, open field test or loose feather test behaviour, although age effects in all three tests indicated a reduction in fearfulness and/or an increase in exploratory behaviour with increasing age. 4. White Leghorns showed longer TI durations than the other strains but less pecking at fixed feather bundles than ISA Browns and Columbian Blacktails. 5. There were few associations between behaviour in the 5 different tests, indicating that birds did not have overall behavioural traits that were consistent across different contexts. This suggests hens cannot easily be categorised into different behavioural 'types', based on their test responses and casts doubt on the usefulness of tests as predictors of feather pecking.
|
|
|
|
Barrey, E., Desliens, F., Poirel, D., Biau, S., Lemaire, S., Rivero, J. L. L., et al. (2002). Early evaluation of dressage ability in different breeds. Equine Vet J Suppl, (34), 319–324.
Abstract: Dressage is one of the Olympic equestrian sports practiced in several countries using different horse breeds. Specific characteristics of the walk, trot and canter are required for dressage. It has been assumed that some of these traits could be selected for genetically and contribute to dressage performance. The purpose of this study was to compare the walk, trot and conformation characteristics in young horses of different breeds used for dressage. A total of 142 horses age 3 years were classified into 3 groups of breeds (German, French and Spanish saddle horses) and tested using the same procedure. The skeletal conformation measurements were made by image analysis. Gait variables of the walk and trot were measured by the accelerometric gait analysis system Equimetrix. Discriminant analysis could explain the variability between the groups by taking into account the walk (P<0.0003), trot (P<0.0001) and conformation variables (P<0.0001). Many gait and conformation variables were significantly different between the breeds. In summary, the German horses had gait characteristics more adapted for dressage competition, and the results of this group could be used as a reference for early evaluation in dressage. Purebred Spanish horses could be considered as a reference for collected gaits used for farm work and old academic dressage. The gait and conformation tests could be applied in a breeding or crossing plan to detect more accurately young horses with good dressage ability.
|
|
|
|
Benhajali, H., Richard-Yris, M. - A., Ezzaouia, M., Charfi, F., & Hausberger, M. (2010). Reproductive status and stereotypies in breeding mares: A brief report. Appl. Anim. Behav. Sci., 128(1-4), 64–68.
Abstract: The aim of this study was to investigate the relationship between age, reproductive status and sire of the mare and the tendency to perform stereotypies. One hundred and fourteen purebred Arab mares, offspring of 39 sires ( offspring per sire) and aged 4-21 years () were observed from the 30th March to the 15th of May 2005 using instantaneous scan sampling. We used a multivariate logistic regression in order to study the relationship between age, reproductive status and sire of the mare and the tendency to perform stereotypies. 28% of the observed mares showed stereotypic behaviour, mostly weaving (22%). Neither age (χ2 Wald = 9.36, p = 0.89) nor sire (χ2 Wald = 4.34, p = 1.0) affected the occurrence of stereotypies whilst the reproductive status of the mare influenced significantly the occurrence (χ2 Wald = 10.75, p = 0.001) but also the type (χ2 = 12.1, p < 0.001) of stereotypic behaviour. Weaving was more frequent in non foaling mares (41.4%) than in foaling mares (1.8%) that performed mostly stall-walking.
|
|
|
|
Clutton-Brock, T. H., Russell, A. F., Sharpe, L. L., Brotherton, P. N., McIlrath, G. M., White, S., et al. (2001). Effects of helpers on juvenile development and survival in meerkats. Science, 293(5539), 2446–2449.
Abstract: Although breeding success is known to increase with group size in several cooperative mammals, the mechanisms underlying these relationships are uncertain. We show that in wild groups of cooperative meerkats, Suricata suricatta, reductions in the ratio of helpers to pups depress the daily weight gain and growth of pups and the daily weight gain of helpers. Increases in the daily weight gain of pups are associated with heavier weights at independence and at 1 year of age, as well as with improved foraging success as juveniles and higher survival rates through the first year of life. These results suggest that the effects of helpers on the fitness of pups extend beyond weaning and that helpers may gain direct as well as indirect benefits by feeding pups.
|
|
|
|
Collery, L. (1974). Observations of equine animals under farm and feral conditions. Equine Vet J, 6(4), 170–173.
|
|
|
|
Creel, S. (2001). Social dominance and stress hormones. Trends. Ecol. Evol, 16(9), 491–497.
Abstract: In most cooperatively breeding birds and mammals, reproductive rates are lower for social subordinates than for dominants, and it is common for reproduction in subordinates to be completely suppressed. Early research conducted in captivity showed that losing fights can increase glucocorticoid (GC) secretion, a general response to stress. Because GCs can suppress reproduction, it has been widely argued that chronic stress might underlie reproductive suppression of social subordinates in cooperative breeders. Contradicting this hypothesis, recent studies of cooperative breeders in the wild show that dominant individuals have elevated GCs more often than do subordinates. The findings that elevated GCs can be a consequence of subordination or a cost of dominance complicate the conventional view of social stress, with broad ramifications for the evolution of dominance and reproductive suppression.
|
|
|
|
Drent, P. J., van Oers, K., & van Noordwijk, A. J. (2003). Realized heritability of personalities in the great tit (Parus major). Proc Biol Sci, 270(1510), 45–51.
Abstract: Behaviour under conditions of mild stress shows consistent patterns in all vertebrates: exploratory behaviour, boldness, aggressiveness covary in the same way. The existence of highly consistent individual variation in these behavioural strategies, also referred to as personalities or coping styles, allows us to measure the behaviour under standardized conditions on birds bred in captivity, link the standardized measurements to the behaviour under natural conditions and measure natural selection in the field. We have bred the great tit (Parus major), a classical model species for the study of behaviour under natural conditions, in captivity. Here, we report a realized heritability of 54 +/- 5% for early exploratory behaviour, based on four generations of bi-directional artificial selection. In addition to this, we measured hand-reared juveniles and their wild-caught parents in the laboratory. The heritability found in the mid-offspring-mid-parent regression was significantly different from zero. We have thus established the presence of considerable amounts of genetic variation for personality types in a wild bird.
|
|
|
|
Dubois, C., Manfredi, E., & Ricard, A. (2008). Optimization of breeding schemes for sport horses. Livestock Science, 118(1-2), 99–112.
Abstract: A selection scheme for jumping sport horses is modelled with four stages of selection for males and one stage for females. The selection objective included three traits: conformation and gaits (CG, weighted 20%), competition jumping (CJ, weighted 60%) and a third trait (TT, weighted 20%) such as sperm quality or orthopaedic status. The first selection stage is based on knowledge of the pedigree with the aim of selecting horses suitable for CG test (at 3Â years old) and CJ test (at 5Â years old). The second stage includes the horse's own performance with respect to CG and CJ with the aim of selecting horses suitable for the TT test. The third stage is the selection of a limited number of males who are allowed to reproduce. The fourth stage (at 12Â years old) takes into account the results of the horse's progeny. Females are selected in one step, whatever the number of performances measured at 5Â years old. The annual genetic response was 9.4% genetic standard deviation of the objective, 2.6% for CG, 9.0% for CJ and 1.5% for TT. Results showed that selection by progeny testing did not contribute much to genetic response (12% of progeny issued from proven sires), the female pathway represented 26% of genetic response, TT was difficult to improve when the genetic correlation was unfavourable (-Â 0.6% genetic standard deviation for -Â 0.20 genetic correlation), and should consequently be directed towards the use of molecular markers. When compared with a selection scheme involving a station test, genetic response was the same if the breeding values used for selection before entering the station test took into account the results of the relatives for CJ and CG. This revealed the importance of an extensive performance test (like for competition performance) when designing breeding schemes for sport horses.
|
|
|
|
Dyson, S., & Murray, R. (2003). Pain associated with the sacroiliac joint region: a clinical study of 74 horses. Equine Vet J, 35(3), 240–245.
Abstract: REASONS FOR PERFORMING STUDY: There has been no large study of horses with suspected sacroiliac (SI) joint region pain in which the clinical diagnosis has been supported by either abnormal radiopharmaceutical activity in the SI joint region or by periarticular infiltration of local anaesthetic solution. OBJECTIVES: To describe the clinical features of horses with SI joint region pain, to document the age, breed, sex, discipline, size and conformation of affected horses and to compare these with the author's (SD) normal case population and to document the results of infiltration of local anaesthetic solution around the SI joint region. METHODS: Horses were selected for inclusion in the study based upon the exclusion of other causes of lameness or poor performance, together with clinical signs suggestive of SI joint pain and abnormal radiopharmaceutical activity in the SI joint region and/or a positive response to periarticular infiltration of local anaesthetic solution. RESULTS: Sacroiliac joint region disease was identified in 74 horses between November 1997 and March 2002. Dressage and showjumping horses appeared to be at particular risk (P < 0.001). Affected horses were generally slightly older than the normal clinic population (P < 0.0001), taller at the withers (P < 0.0001) and of greater bodyweight (P < 0.01). There was a significant effect of breed (P < 0.001), with a substantially higher proportion of Warmblood horses (51%) in the SI pain group compared to the normal clinic population (29%). There was no correlation between conformation and the presence of SI joint region pain. The tubera sacrale appeared grossly symmetrical in most (95%) horses. Poor development of the epaxial muscles in the thoracolumbar region and asymmetry of the hindquarter musculature were common. Twenty-six horses (35%) showed restricted flexibility of the thoracolumbar region and 10 (16%) had an exaggerated response to pressure applied over the tubera sacrale. Fourteen horses (19%) were reluctant to stand on one hindlimb for prolonged periods. The majority of horses (75%) had a straight hindlimb flight and only 18% moved closely behind or plaited. In all horses restricted hindlimb impulsion was the predominant feature; invariably this was most obvious when the horse was ridden. Stiffness, unwillingness to work on the bit and poor quality canter were common. Sacroiliac joint region pain was seen alone (47%), or in conjunction with thoracolumbar pain (16%), hindlimb lameness (20%), forelimb lameness (7%) or a combination of problems (10%). Seventy-three horses (99%) had abnormalities of the SI joint region identified using nuclear scintigraphy. Infiltration of local anaesthetic solution around the SI joint region produced profound improvement in gait in all 34 horses in which it was performed. CONCLUSIONS AND POTENTIAL RELEVANCE: Careful clinical examination combined with scintigraphic evaluation of the SI joint region and local analgesia can enable a more definitive diagnosis of SI joint region pain than has previously been possible.
|
|
|
|
Hamilton, W. D. (1971). Geometry for the selfish herd. J. Theor. Biol., 31(2), 295–311.
Abstract: This paper presents an antithesis to the view that gregarious behaviour is evolved through benefits to the population or species. Following Galton (1871) and Williams (1964) gregarious behaviour is considered as a form of cover-seeking in which each animal tries to reduce its chance of being caught by a predator.
It is easy to see how pruning of marginal individuals can maintain centripetal instincts in already gregarious species; some evidence that marginal pruning actually occurs is summarized. Besides this, simply defined models are used to show that even in non-gregarious species selection is likely to favour individuals who stay close to others.
Although not universal or unipotent, cover-seeking is a widespread and important element in animal aggregation, as the literature shows. Neglect of the idea has probably followed from a general disbelief that evolution can be dysgenic for a species. Nevertheless, selection theory provides no support for such disbelief in the case of species with outbreeding or unsubdivided populations.
The model for two dimensions involves a complex problem in geometrical probability which has relevance also in metallurgy and communication science. Some empirical data on this, gathered from random number plots, is presented as of possible heuristic value.
|
|
