赛鸽咏调录

鸽声如潮 鸽子在求偶时发出的声音有时如波涛汹涌．有时如潺潺流水，有时又似风平浪静、温柔可亲的娓娓之声。它们在相聚中是那样渴望对方情欲的释放，它们在求爱时是那样翩翩起舞而又舞姿优美，它们在情欲的释放中又是那样穷追不舍地施爱。求得配偶的欢心并给予回应是它们生理的需求．也是它们繁殖后代的责任。情哥（鸽）能配上“西施”（美鸽）是鸽子们一生中最重要的时期．也是育种的关健时期．抓住这个时期就抓住了希望。     

浅议赛鸽育种之路

在赛鸽育种之路上我们鸽友不要盲目地推崇,而要注重实践。要关于积累,不断总结,才能育得精彩,赢得明白。     

养鸽和赛鸽的良师益友

在每个养鸽爱好者的养鸽生涯中，由于很少有名家高手作为师父言传身教，因此，鸽刊杂志理所当然地成为了鸽友们获取知识的源泉。     

Genetic evaluation of Swedish standard-bred trotters for racing performance traits and racing status

The BLUP methodology has been applied to the genetic evaluation of Swedish standard-bred trotters for well over a decade. Initially a BLUP sire model was applied for evaluating breeding values of stallions on the basis of the racing performance of their offspring (Árnason et al. 1989). In 1992 an animal model (AM-) BLUP was introduced and official publication of index values were offered as an aid for effective selection of stallions and brood mares (Árnason 1992; Árnason and S vendsen 1991). The implementation of the BLUP animal model index has apparently caused profound enhancement in the selection intensity for both stallions and mares (Árnason 1997). The AM-BLUP evaluation has involved the following traits, which were all based on accumulated racing results as 3- to 5-year-olds: Number of races (starts); % of races ranked first to third at the finish (i.e. placed first to third); earnings per race; total earnings; best racing time per km; and racing (or start) status, which is denoted as one if the horse did race at least once as a 3- to 5-year-old and zero otherwise. The two traits: number of races and racing status were initially treated as single traits, in the AM-BLUP analyses, uncorrelated with the other racing performance traits. Those other traits are direct measures of racing performance for horses that have actually competed on the race track. They are highly intercorrelated and have been treated as a multivariate complex in the analyses. The computational load of general multivariate analyses has been considerably reduced by transformation of the records into uncorrelated canonical variates (e.g. Árnason 1982). In Sweden, about 40% of standard-bred trotters do not enter a race course and their racing performance variables have previously been treated as missing. Early analysis on the population of standard-bred trotters in Sweden did not show any correlation between racing status of brood mares and the racing performance of their offspring (M. B endroth , unpublished results). That gave justification for assuming that racing status had mainly environmental causes, and to be practically genetically uncorrelated with performance. The exclusion of nonracers (nonstarters) was therefore not expected to bias genetic evaluations for the performance traits. The expansion of the population during the 1980s and the early 1990s, and increase in the level of prize money, has probably invalidated the implication of these results and partly changed the racing status into a preselection criterion for racing performance. K lemetsdal (1992) has clearly illustrated that such a culling process can result in substantial bias in estimated breeding values. In 1995 a new enhanced procedure replaced the older version used for routine genetic evaluation of Swedish standard-bred trotters, with the aim of eliminating, or at least reducing, the selection bias and increasing the accuracy in the genetic evaluations. The main objective of this paper was to describe the enhanced procedure for genetic evaluation of Swedish standard-bred trotters where racing status and racing performance traits were treated in a complete multiple trait framework. The task was made computationally feasible by the application of a procedure which allows solution of multiple trait AM-BLUP with missing data on some traits using multiple step canonical transformation of records and solutions during the iterative solution phase (D ucrocq and B esbes 1993). The pertinence of the method for establishing a sound selection criterion was verified by stochastic simulations on simplified data structures. The second objective of this study was to evaluate the model and assess the set of genetic parameters used in the BLUP analysis, by linear regressions of the genetic predictions based on the most recent data on genetic predictions obtained in subsamples of the whole data set (method R, R everter et al. 1994a, b).     

Effects of racing and training on serum thyroid hormone concentrations in racing Greyhounds.

OBJECTIVES: To determine the effects of racing and training on serum thyroxine (T4), triiodothyronine (T3), and thyroid stimulating hormone (TSH) concentrations in Greyhounds. ANIMALS: 9 adult racing Greyhounds. PROCEDURE: Serum thyroid hormone concentrations were measured before and 5 minutes after a race in dogs trained to race 500 m twice weekly for 6 months. Resting concentrations were measured again when these dogs had been neutered and had not raced for 3 months. Postrace concentrations were adjusted relative to albumin concentration to allow for effects of hemoconcentration. Thyroid hormone concentrations were then compared with those of clinically normal dogs of non-Greyhound breeds. RESULTS: When adjusted for hemoconcentration, total T4 concentrations increased significantly after racing and TSH concentrations decreased; however, there was no evidence of a change in free T4 or total or free T3 concentrations. Resting total T4 concentrations increased significantly when dogs had been neutered and were not in training. There was no evidence that training and neutering affected resting TSH, total or free T3, or free T4 concentrations. Resting concentrations of T3, TSH, and autoantibodies against T4, T3, and thyroglobulin were similar to those found in other breeds; however, resting free and total T4 concentrations were lower than those found in other breeds. CONCLUSIONS AND CLINICAL RELEVANCE: Except for total T4, thyroid hormone concentrations in Greyhounds are affected little by sprint racing and training. Greyhounds with low resting total and free T4 concentrations may not be hypothyroid.     

A longitudinal study of racing thoroughbreds: performance during the first years of racing

OBJECTIVES: To develop a profile of the racing careers of Thoroughbred horses in south-eastern Queensland, and to examine factors that affect racing during the first years of racing. DESIGN AND PROCEDURE: A longitudinal study using the racing records of a defined cohort of Thoroughbred horses that were born on or within 12 months following 1 August 1991. Data collection commenced in 1996 and will continue until all horses cease racing. In this paper two measures of performance were examined: race earnings during the first year of racing and cumulative proportion of horses still racing up to 2 years after their first start. Univariable and multivariable methods were used to describe and identify factors associated with the performance of these horses. RESULTS: By 31 July 1997, 1804 horses were enrolled in the study including 916, 701, 152 and 35 horses that first raced at 2, 3, 4 and 5 years of age, respectively. During their first year of racing, half the horses earned no more than A$450 from race earnings, and 710 (39.4%) horses earned no money at all. In comparison to poorly performing horses, well-performing horses were more likely to be male, to have started as 2-year-olds and to have had more starts during this year. Of the horses that first started as 2 and 3-year-olds, only 71 and 46% continued racing for at least 1 and 2 years after their first start, respectively. Length of racing life was associated with performance during the first year of racing (number of starts and average earnings per race), and with sex, date of birth and age at first start. CONCLUSIONS: The study confirmed a high wastage among racing Thoroughbreds. As expected, premature retirement from racing was linked to poor performance. During the first year of racing, the race earnings of an estimated 1567 (86.9%) horses were insufficient to cover training costs. The 2-year-old racing cohort outperformed the older racing cohorts in each of the performance measures under investigation. Interpretation of this result, and the long-term effects of 2-year-old racing, was limited by the problem of confounding.