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Martin Weggler - One of the best experts on this subject based on the ideXlab platform.
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age related reproductive success in dichromatic male black redstarts phoenicurus ochruros why are Yearlings handicapped
Ibis, 2001Co-Authors: Martin WegglerAbstract:Reproductive constraints on sexually mature, young birds may be the underlying cause for the evolution and maintenance of delayed plumage maturation in passerine birds. 1 examined whether yearling male Black Redstarts in non-definitive plumage are reproductively handicapped and explored possible reasons for it. Yearlings raised only half as many young per season as adults. Differential reproductive effort was excluded as a possible source for age-related reproductive success because Yearlings and adults did not differ in the frequency of non-breeding or in paternal effort. The lower annual reproductive success of Yearlings was attributed to their lower probability of obtaining (multiple) females and adult females. Males mated to adult females raised almost twice as many offspring as males mated to yearling females. I conclude that the proposed preconditions for the evolution and maintenance of delayed plumage maturation do still prevail in the Black Redstart.
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Age‐related reproductive success in dichromatic male Black Redstarts Phoenicurus ochruros: Why are Yearlings handicapped?
Ibis, 2001Co-Authors: Martin WegglerAbstract:Reproductive constraints on sexually mature, young birds may be the underlying cause for the evolution and maintenance of delayed plumage maturation in passerine birds. 1 examined whether yearling male Black Redstarts in non-definitive plumage are reproductively handicapped and explored possible reasons for it. Yearlings raised only half as many young per season as adults. Differential reproductive effort was excluded as a possible source for age-related reproductive success because Yearlings and adults did not differ in the frequency of non-breeding or in paternal effort. The lower annual reproductive success of Yearlings was attributed to their lower probability of obtaining (multiple) females and adult females. Males mated to adult females raised almost twice as many offspring as males mated to yearling females. I conclude that the proposed preconditions for the evolution and maintenance of delayed plumage maturation do still prevail in the Black Redstart.
Elwyn C. Firth - One of the best experts on this subject based on the ideXlab platform.
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exercise in thoroughbred Yearlings during sales preparation a cohort study
Equine Veterinary Journal, 2012Co-Authors: Charlotte F. Bolwell, Chris W. Rogers, Nigel P. French, Elwyn C. FirthAbstract:Summary Reasons for performing study: There is increasing evidence suggesting that early exercise in Thoroughbred racehorses may be beneficial to the development of the musculoskeletal system. At present, information on the exercise programmes and health problems of individual Yearlings during a sales preparation is scant. Objectives: To describe the exercise and health problems of Thoroughbred Yearlings during preparation for sales, and to identify variations in exercise between and within farms. Methods: A prospective cohort study was used to collect exercise and health information from 18 farms across New Zealand. Daily exercise records for individual horses were recorded during the studfarms' preparation for the annual national yearling sales in January 2009. Results: Data were collected from 319 Yearlings, of which 283 (88.7%) were exercised (hand walking, mechanical walker and lungeing) during their preparations. Sales preparation lasted a median of 69 days (interquartile range 61–78) and differed significantly between farms (P<0.001). The median exercise time performed differed significantly by gender (P<0.001), farm (P<0.001) and month of the preparation (P<0.001), but not by type of sale (P = 0.14) or category of sales price (P = 0.12). Within certain farms, daily exercise differed between horses as did total exercise by gender and the number of days spent in the sales preparation. Lameness was the most common condition affecting Yearlings and the overall incidence rate of lameness was 0.08 per 100 horse days (95% confidence interval 0.05–0.13). Incidence rates of lameness varied significantly between farms (P = 0.02), but not by age (P = 0.77), sales type (P = 0.58) or month of the preparation (P = 0.53). Conclusions and potential relevance: Yearling exercise programmes varied between and within farms. Since exercise is already being tailored for each individual horse, there may be an opportunity to allow for modifications to sales preparation with the future career in mind.
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Exercise in Thoroughbred Yearlings during sales preparation: A cohort study
Equine Veterinary Journal, 2011Co-Authors: Charlotte F. Bolwell, Chris W. Rogers, Nigel P. French, Elwyn C. FirthAbstract:Summary Reasons for performing study: There is increasing evidence suggesting that early exercise in Thoroughbred racehorses may be beneficial to the development of the musculoskeletal system. At present, information on the exercise programmes and health problems of individual Yearlings during a sales preparation is scant. Objectives: To describe the exercise and health problems of Thoroughbred Yearlings during preparation for sales, and to identify variations in exercise between and within farms. Methods: A prospective cohort study was used to collect exercise and health information from 18 farms across New Zealand. Daily exercise records for individual horses were recorded during the studfarms' preparation for the annual national yearling sales in January 2009. Results: Data were collected from 319 Yearlings, of which 283 (88.7%) were exercised (hand walking, mechanical walker and lungeing) during their preparations. Sales preparation lasted a median of 69 days (interquartile range 61–78) and differed significantly between farms (P
Olof Liberg - One of the best experts on this subject based on the ideXlab platform.
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patterns of dispersal and seasonal migration in roe deer capreolus capreolus
Journal of Zoology, 1995Co-Authors: L K Wahlstrom, Olof LibergAbstract:Roe deer (Capreolus capreolus) spacing behaviour, during the period between mother-fawn separation and home range establishment, was studied in southern Sweden during 1987–1992. Data were collected, using telemetry, in two non-hunted populations. Females dispersed either as Yearlings, or as 2- or 3-year-olds after having migrated between non-overlapping summer and winter ranges for one and two seasons, respectively. Seasonal migration usually ended with permanent settlement in the new summer area. Males dispersed as one- or two-year-olds, or remained philopatric. Median distance moved was c. 2 km with no significant sex-bias. Both populations underwent one increase, and one stable phase. During the increase phase, the frequency of yearling dispersal was 70% in one of the populations, but dropped to 20% at high density. This drop paralleled a 14% decrease in yearling winter weights. In the other population, yearling dispersal frequency was 56% during the increase phase. This population stopped increasing at an intermediate density and dispersal frequency was kept at 75%. Weights remained high in this population. In neither of the populations, at intermediate and high densities, was a sex-bias in dispersal among Yearlings evident. Dispersers were on average heavier than philopatrics. High juvenile winter weight did not predestinate Yearlings to dispersal, whereas low weight seemed to prevent dispersal. On the basis of these relationships, we propose a hypothesis relating dispersal to body condition, in order to explain dispersal tendency at different population densities. Further, we suggest the reason for female migration is the advantage of residing in a group during winters when predation risk is high. Since it is difficult for females (but not for males) to join non-relatives, dispersers must go back to the natal area as long as they have too few offspring to form their own matriarchal group.
Charlotte F. Bolwell - One of the best experts on this subject based on the ideXlab platform.
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The efficacy of Ivermectin against strongyles in Yearlings on Thoroughbred breeding farms in New Zealand.
Veterinary Parasitology: Regional Studies and Reports, 2017Co-Authors: Sarah M. Rosanowski, Charlotte F. Bolwell, Ian M. Scott, Patrick D. Sells, Chris W. RogersAbstract:Abstract Against a global background of increasing anthelmintic resistance in parasites and a domestic over-reliance on anthelmintics to control gastrointestinal parasites, little is currently known about the resistance status of equine parasites in New Zealand. The objective of the study was to investigate the efficacy of ivermectin in yearling Thoroughbreds. Data were collected from six stud farms from November 2014 to January 2015. Yearlings were selected based on not being treated with anthelmintics for a minimum of six weeks previously and on having a preliminary screening strongyle faecal egg count (FEC) of 25 eggs per gram (EPG) of faeces or greater. On Day 0, faeces were collected and Yearlings were treated with ivermectin (a minimum of 200 μg/kg). On Days 7, 14 and 21 faeces were again collected from the Yearlings, with follow-up samples take on either Day 28, 35 or 42 depending on the stud farm. In total, six stud farms and 117 Yearlings (median 23 Yearlings; range 5 to 27 Yearlings per stud) were eligible for the study. The mean FEC on Day 0 was 609.6 EPG (range 100 to 2000). The majority of horses (113/117) had zero egg counts 7-days after treatment. One and five horses had positive FEC 14 and 21 days' post-treatment, respectively. The efficacy of ivermectin ranged from 99.8% to 100% on Day 7 to between 98.5% and 100% on Day 21. On one stud, the efficacy on day 14 was 94.4%. There was reduced efficacy ( n = 7), egg counts remained zero up to 42 days' post-treatment. The FECRT observed could be interpreted as consistent with the continued efficacy of ivermectin in the egg-laying adult stages. However, shortened ERP after ivermectin treatment is a concern and current practices for parasite control in horses in New Zealand are arguably not sustainable.
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exercise in thoroughbred Yearlings during sales preparation a cohort study
Equine Veterinary Journal, 2012Co-Authors: Charlotte F. Bolwell, Chris W. Rogers, Nigel P. French, Elwyn C. FirthAbstract:Summary Reasons for performing study: There is increasing evidence suggesting that early exercise in Thoroughbred racehorses may be beneficial to the development of the musculoskeletal system. At present, information on the exercise programmes and health problems of individual Yearlings during a sales preparation is scant. Objectives: To describe the exercise and health problems of Thoroughbred Yearlings during preparation for sales, and to identify variations in exercise between and within farms. Methods: A prospective cohort study was used to collect exercise and health information from 18 farms across New Zealand. Daily exercise records for individual horses were recorded during the studfarms' preparation for the annual national yearling sales in January 2009. Results: Data were collected from 319 Yearlings, of which 283 (88.7%) were exercised (hand walking, mechanical walker and lungeing) during their preparations. Sales preparation lasted a median of 69 days (interquartile range 61–78) and differed significantly between farms (P<0.001). The median exercise time performed differed significantly by gender (P<0.001), farm (P<0.001) and month of the preparation (P<0.001), but not by type of sale (P = 0.14) or category of sales price (P = 0.12). Within certain farms, daily exercise differed between horses as did total exercise by gender and the number of days spent in the sales preparation. Lameness was the most common condition affecting Yearlings and the overall incidence rate of lameness was 0.08 per 100 horse days (95% confidence interval 0.05–0.13). Incidence rates of lameness varied significantly between farms (P = 0.02), but not by age (P = 0.77), sales type (P = 0.58) or month of the preparation (P = 0.53). Conclusions and potential relevance: Yearling exercise programmes varied between and within farms. Since exercise is already being tailored for each individual horse, there may be an opportunity to allow for modifications to sales preparation with the future career in mind.
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Exercise in Thoroughbred Yearlings during sales preparation: A cohort study
Equine Veterinary Journal, 2011Co-Authors: Charlotte F. Bolwell, Chris W. Rogers, Nigel P. French, Elwyn C. FirthAbstract:Summary Reasons for performing study: There is increasing evidence suggesting that early exercise in Thoroughbred racehorses may be beneficial to the development of the musculoskeletal system. At present, information on the exercise programmes and health problems of individual Yearlings during a sales preparation is scant. Objectives: To describe the exercise and health problems of Thoroughbred Yearlings during preparation for sales, and to identify variations in exercise between and within farms. Methods: A prospective cohort study was used to collect exercise and health information from 18 farms across New Zealand. Daily exercise records for individual horses were recorded during the studfarms' preparation for the annual national yearling sales in January 2009. Results: Data were collected from 319 Yearlings, of which 283 (88.7%) were exercised (hand walking, mechanical walker and lungeing) during their preparations. Sales preparation lasted a median of 69 days (interquartile range 61–78) and differed significantly between farms (P
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production variables influencing the auction sales price of new zealand thoroughbred Yearlings
Proceedings of the New Zealand Society of Animal Production 2011., 2011Co-Authors: K Waldron, C W Rogers, E K Gee, Charlotte F. BolwellAbstract:Data were obtained from the New Zealand Thoroughbred studbook and the online sales results for the 2004 National Yearling Sales Series. Across the three sales categories, 477, 523, and 354 Yearlings were offered at the Premier, Select and Festival sales, respectively. There were significant differences in the representation of Yearlings across the three sales categories based on: sire service fee, vendor category, purchaser country of origin, and dam age. There were fewer fillies catalogued in the Festival sale compared to Select or Premier sales (P <0.05). Within the general linear model, auction price (log10) was significantly influenced by sales category: Premier ($71,285, 95% Confidence interval (CI), $61,801-$82,224), Select ($24,831, 95% CI, $22,233-$27,733) and Festival ($9,462, 95% CI, $8,072-$11,091, P <0.001). Sales price (log10) was also significantly influences by sire service fee, vendor category, purchaser country of origin, and mare age. Colts sold for more than fillies ($29,040, 95% CI, $26,668-$31,695 vs. $22,542, 95% CI, $20,370$24,945, P <0.001) across all sales categories with an interaction of sales category and gender (P = 0.003). These results indicate that in order to optimize gross returns, vendors require colts that are marketed through the Premier sale, from older established broodmares, with a pedigree that appeals to Australian buyers.
L K Wahlstrom - One of the best experts on this subject based on the ideXlab platform.
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patterns of dispersal and seasonal migration in roe deer capreolus capreolus
Journal of Zoology, 1995Co-Authors: L K Wahlstrom, Olof LibergAbstract:Roe deer (Capreolus capreolus) spacing behaviour, during the period between mother-fawn separation and home range establishment, was studied in southern Sweden during 1987–1992. Data were collected, using telemetry, in two non-hunted populations. Females dispersed either as Yearlings, or as 2- or 3-year-olds after having migrated between non-overlapping summer and winter ranges for one and two seasons, respectively. Seasonal migration usually ended with permanent settlement in the new summer area. Males dispersed as one- or two-year-olds, or remained philopatric. Median distance moved was c. 2 km with no significant sex-bias. Both populations underwent one increase, and one stable phase. During the increase phase, the frequency of yearling dispersal was 70% in one of the populations, but dropped to 20% at high density. This drop paralleled a 14% decrease in yearling winter weights. In the other population, yearling dispersal frequency was 56% during the increase phase. This population stopped increasing at an intermediate density and dispersal frequency was kept at 75%. Weights remained high in this population. In neither of the populations, at intermediate and high densities, was a sex-bias in dispersal among Yearlings evident. Dispersers were on average heavier than philopatrics. High juvenile winter weight did not predestinate Yearlings to dispersal, whereas low weight seemed to prevent dispersal. On the basis of these relationships, we propose a hypothesis relating dispersal to body condition, in order to explain dispersal tendency at different population densities. Further, we suggest the reason for female migration is the advantage of residing in a group during winters when predation risk is high. Since it is difficult for females (but not for males) to join non-relatives, dispersers must go back to the natal area as long as they have too few offspring to form their own matriarchal group.
