Estimates of non-genetic effects and genetic parameters for body measures and subjectively scored traits in Finnhorse trotters

This study examined non-genetic effects and genetic parameters of body measures and subjectively scored traits in the Finnhorse trotter population. The data was based on studbook inspections from 1971 to 2004 covering observations on 6381 horses. There were five body measures – height at withers, height at croup, circumference of girth, length of body and circumference of cannon bone – and six subjectively scored traits – character, body conformation, leg stances, quality of legs, hooves and movements – included in the analyses. Multivariate mixed models were applied with year–sex and age as fixed effects and animal as a random effect. The year–sex effect had a significant influence on body measures and scored traits. Age at judging had a significant influence on all traits but height at withers and body conformation. Heritability estimates were from 0.53 to 0.78 for body measures and 0.10 to 0.19 for scored traits. Genetic correlations between body measures were highly positive, from 0.75 to 0.98, whilst genetic correlations between scored traits varied between − 0.20 and 0.51. Genetic correlations between body measures and scored traits were mainly negative, from − 0.38 to 0.09. Our results indicate that additive genetic effects are relevant determinants for body measures of Finnhorse trotters. The scored traits were of low to moderate heritability and were relevantly influenced by environmental effects.     

Genetic analyses for linear conformation traits in Pura Raza Español horses

A linear assessment methodology was developed for the conformational data in the Pura Raza Español horse (Andalusian horse). The final design included 31 linear traits (20 primary and 11 secondary). A total of 4158 records from 2512 horses collected during 2008 and 2011 were included in the genetic evaluation. The genetic analyses were executed twice, the first one only with the first conformation assessment record of each animal (dataset 1: 2512 horses and records), and the second one, only for animals with more than one conformation records available (dataset 2: 876 horses and 2522 records). Genetic parameters were estimated using REML methodology (in a linear animal model), and age, sex, geographic region and combination of appraiser×event were included as fixed effects in the model. For the analysis with dataset 2, permanent environment was also included as random effect. The pedigree file traced back the relationships to include a total of 12,385 (dataset 1) and 3025 (dataset 2) horses. After the repeatability and reproducibility of the system were evaluated, according to our results, the appraisers used the whole scale and showed an adequate level of repeatability (≥0.95), and the reproducibility of analyzed traits was over 0.90 for all traits. Despite the fact that the quality of the morphological assessment can be considered adequate, further training is recommendable for appraisers in order to improve uniformity. Heritabilities with dataset 1 were low-moderate, ranging from 0.06±0.026 (angle of shoulder) to 0.35±0.044 (head length) for the primary traits, and from 0.08±0.032 (frontal angle of knee) to 0.23±0.035 (head-neck junction) for the secondary ones. Heritabilities found with dataset 2 were slightly lower than those obtained with dataset 1. Genetic correlations between traits were also obtained, which ranged from 0.92 to 0.00 in both datasets. These results must be taken into account in order to reduce the number of traits routinely collected in this population.     

Effects of Jugular Vein Occlusion on Cardiovascular Parameters in Horses During Exercise on a Treadmill

The purpose of the present investigation was to examine the effects of unilateral and bilateral jugular vein occlusion by temporary surgical ligature on the heart rate and arterial and venous blood pressure in sedentary horses during progressive treadmill exercise. Six horses performed three exercise tests (ET). ET1, considered the control, was performed in horses without jugular occlusions. ET2 and ET3 were performed with unilateral and bilateral occlusion by temporary surgical ligature of the jugular veins, respectively. Heart rate, arterial pressure, and pressure of the occluded jugular vein were evaluated. Clinically, the horses presented apathy, head edema, congested mucous membranes, increased capillary refill time, and dysphagia. These signs were observed with the unilateral jugular vein occlusion and became more evident with the bilateral occlusion. Comparing ETs, no differences were observed in heart rate. However, jugular occlusions promoted a decrease in the mean arterial pressure and a severe increase in jugular pressure. Head edema caused by the jugular vein occlusion in the horses could interfere with the autonomic cardiovascular regulation of arterial blood pressure during exercise, likely leading to an impairment of tissue perfusion. Jugular occlusion, even unilateral, also causes severe head venous congestion, leading to venous hypertension that was aggravated by exercise, which could risk development of cerebral edema and neurological damage. The present results obtained from sedentary horses are preliminary data that lead us to suggest that sport horses presenting jugular occlusive thrombophlebitis, even unilateral, may be prevented from performing athletic activities.     

肉鸡腹脂的遗传

利用成年肉鸡组建家系,得到222个有血缘关系的后代。70日龄肉鸡公母间腹脂重或腹脂相对重差异均极显著(P<0.01)。腹脂相对重与宰前活重的表型相关相对较小,与屠体重呈负的遗传相关(r_A=-0.14)。所以,以腹脂相对重做为肉鸡的肥度指标较合理。腹脂重或腹脂相对重高度遗传(h~2=0.48和0.52),且变异大(C.V.>30％)。腹脂重或腹脂相对重与屠体重呈较弱的负遗传相关。所以,对腹脂性状进行选择不会影响产肉性能。     

Genetic analysis of six production traits in Peruvian alpacas

In this study a total of 6499 records were obtained for fibre diameter (FD) and coefficient of variation of FD (CV), 3283 records for greasy fleece weight (GFW), staple length (SL) and shearing interval (SI) and 1802 records of textile value index (TV) obtained from an experimental herd of alpacas exploited in the Peruvian Altiplano.The estimated heritabilities were: 0.412 ± 0.015 (FD), 0.321 ± 0.013 (CV), 0.098 ± 0.016 (GFW), 0.070 ± 0.011 (SL), 0.061 ± 0.012 (SI) and 0.163 ± 0.017 (TV). No significant genetic correlation was found for the pairs FD-CV and CV-GFW whilst the pairs FD-GFW, FD-SI and FD-TV had significant genetic correlations of, respectively, 0.405 ± 0.081, − 0.395 ± 0.078 and − 0.746 ± 0.049. No significant correlations were found for SL except for the pair SL-SI (0.397 ± 0.099). The TV index also showed significant genetic correlations with CV of 0.125 ± 0.061 and with GFW of 0.490 ± 0.070. All estimates of permanent environmental effects (c²) associated with the six analysed traits were statistically significant ranging from 0.008 for SI to 0.259 for CV. Total repeatability for the analysed traits was low for SI (0.069) and SL (0.090), moderate for TV (0.299) and GFW (0.316) and high for FD (0.578) and CV (0.579). The permanent environmental effect associated with CV is significantly correlated with those of the other traits except for FD. The permanent environmental effects associated with GFW and SL seemed to be basically the same (estimated correlation of 0.916 ± 0.062). The permanent environmental effect for TV is highly correlated with those associated with GFW (0.498 ± 0.058) and SL (0.750 ± 0.137). Expected selection response for TV was higher when FD was considered as selection goal instead of TV itself.It would, therefore, be more efficient to use FD rather than empirical indices as selection criterion to increase textile value in Peruvian alpacas. The reported genetic parameters and correlation matrices can be useful to implement multitrait breeding value estimations for alpaca selection.     

奶牛泌乳曲线数学模型的遗传分析

本文采用Wood、改进多项式、回归模型各参数估值及拟合、预报奶量进行了方差分析,遗传力、遗传相关估计及BLUP法育种值估计。方差分析结果表明,产犊季节和胎次对各性状具有较为显著的影响。各遗传相关的估值均较高,这是由环境因素及取样情况所致。实际及估计305天产奶量的遗传力估值较高,Wood模型参数c、改进多项式模型参数d及回归模型参数d、e的遗传力估值也相对较高。各估计、预报奶量及各选定模型参数的BLUP育种值排队序号与实际305天产奶量BLUP育种值排队序号均呈极显著的秩相关(p<0.001).这表明可以用估计和预报奶量及模型参数来评定种公牛的优劣。这对奶牛生产和育种实践具有一定的实践意义。     

Increased Parasite Resistance and Recurrent Airway Obstruction in Horses of a High‐Prevalence Family

Background: Equine recurrent airway obstruction (RAO) shares many characteristics with human asthma. In humans, an inverse relationship between susceptibility to asthma and resistance to parasites is suspected. Hypothesis/Objectives: Members of a high‐incidence RAO half‐sibling family (F) shed fewer strongylid eggs compared with RAO‐unaffected pasture mates (PM) and that RAO‐affected horses shed fewer eggs than RAO‐unaffected half‐siblings. Animals: Seventy‐three F and 73 unrelated, age matched PM. Methods: Cases and controls kept under the same management and deworming regime were examined. Each individual was classified as RAO affected or RAO unaffected and fecal samples were collected before and 1–3 weeks and 3 months after deworming. Samples were analyzed by combined sedimentation‐flotation and modified McMaster methods and classified into 3 categories of 0 eggs per gram of feces (EpG), 1–100 EpG, and >100 EpG, respectively. Results: PM compared with RAO‐affected F had a 16.7 (95% confidence interval [CI]: 2.0–136.3) times higher risk for shedding > 100 EpG compared with 0 EpG and a 5.3 (95% CI: 1.0–27.4) times higher risk for shedding >100 EpG compared with 0 EpG. There was no significant effect when RAO‐unaffected F were compared with their PM. RAO‐unaffected compared with RAO‐affected offspring had a 5.8 (95% CI: 0.0–1.0) times higher risk for shedding 1–100 EpG. Age, sex, breed, and sharing pastures with other species had no significant confounding effects. Conclusion and Clinical Importance: RAO is associated with resistance against strongylid parasites in a high‐prevalence family.     

A review of genetic parameter estimates for wool, growth, meat and reproduction traits in sheep

Genetic parameters for a range of sheep production traits have been reviewed from estimates published over the last decade. Weighted means and standard errors of estimates of direct and maternal heritability, common environmental effects and the correlation between direct and maternal effects are presented for various growth, carcass and meat, wool, reproduction, disease resistance and feed intake traits. Weighted means and confidence intervals for the genetic and phenotypic correlations between these traits are also presented. A random effects model that incorporated between and within study variance components was used to obtain the weighted means and variances. The weighted mean heritability estimates for the major wool traits (clean fleece weight, fibre diameter and staple length) and all the growth traits were based on more than 20 independent estimates, with the other wool traits based on more than 10 independent estimates. The mean heritability estimates for the carcass and meat traits were based on very few estimates except for fat (27) and muscle depth (11) in live animals. There were more than 10 independent estimates of heritability for most reproduction traits and for worm resistance, but few estimates for other sheep disease traits or feed intake. The mean genetic and phenotypic correlations were based on considerably smaller numbers of independent estimates. There were a reasonable number of estimates of genetic correlations among most of the wool and growth traits, although there were few estimates for the wool quality traits and among the reproduction traits. Estimates of genetic correlations between the groups of different production traits were very sparse. The mean genetic correlations generally had wide confidence intervals reflecting the large variation between estimates and relatively small data sets (number of sires) used. More accurate estimates of genetic parameters and in particular correlations between economically important traits are required for accurate genetic evaluation and development of breeding objectives.     

Genetic analysis of clinical findings at health examinations of young Swedish warmblood riding horses

Background

Soundness is important for welfare and utility of the riding horse. Musculoskeletal disorders are the most common causes of interruption in training and of culling. Despite great importance, heritability of a majority of health traits in horses has previously not been estimated. The objective was to perform genetic analyses of medical and orthopaedic health traits in young riding horses, including estimates of heritability and genetic correlations between health traits, and to reveal possibilities for genetic evaluation of stallions for progeny health.

Results

The heritability of health traits was estimated using records from 8,238 Swedish warmblood riding horses examined as 4–5 year olds at the Riding Horse Quality Test in 1983–2005. The analyses were performed using multi-trait linear mixed animal models. The heritabilities of palpatory orthopaedic health (PALP), including effusion, swelling, heat, soreness and stiffness/atrophy, and hoof examination results (HOOF), of hoof shape and hoof wall quality, were 0.12 and 0.10, respectively. The genetic variation in these traits resulted in distinct health differences between progeny groups of stallions. The highest heritability among clinical signs of PALP was found for synovial effusions at 0.14. For systemic locations, joint related findings had the highest heritability; 0.13. The heritabilities of medical health and locomotion examination results were low, 0.02 and 0.04, respectively. A genetic improvement of health status has occurred over time but accounts only partly for the decrease in clinical findings of health during the studied period.

Conclusions

The genetic variation found in PALP and HOOF implies distinct differences between progeny groups. Thus, there are possibilities for improvement of these traits in the population through selection. The weak and non-significant correlation between PALP and HOOF suggests that both traits need to be selected for in practical breeding to improve both traits. Some genetic improvements over time have already been achieved, possibly due to regular stallion health inspections and an indirect selection for lifetime performance. For further improvements stallion breeding values for health may be introduced, based on RHQT examinations, complementary to present breeding values for performance.     

Effects of Shortening Breakover at the Toe on Gait Kinematics at the Walk and Trot

Point of breakover, defined as the portion of the hoof last in contact with the ground during the terminal stance phase of a limb, can be influenced by many factors including craniocaudal placement of the shoe. Shortening the point of breakover has been suggested to decrease strain on the deep digital flexor tendon and navicular bone as well as to improve the alignment of the second and third phalanx. The current experiment involved eight sound horses fitted with aluminum plates adhered to their front hooves, which were drilled and tapped to allow additional aluminum plates of various lengths to be attached (the longest plate was placed flush with the toe, while the shortest plate was moved 3.81 cm caudal to the toe). Horses were recorded on video while at the walk and trot over a distance of 70 meters for six repetitions to determine differences in gait kinematics. Results of this study show significant changes in stride kinematics caused by shortening the point of breakover. Retraction of the forelimbs was greatest when breakover was moved 1.27 cm back from the toe (P < .05), and minimum height of the fetlock at the trot was higher on all treatments where the breakover point was moved caudally (P < .05). Some improvements in gait quality were observed when breakover was shortened, although extreme caudal placement of the shoe (negative placement in relation to P3) resulted in a decrease in gait quality as seen by decreased retraction of the forelimb (P < .05) coupled with hoof height occurring earlier in the stride (P < .05).     

Exploring the possibilities of genetic improvement from traceability data: An example in the Pirenaica beef cattle

The aim of this study is to explore the potential use of the information generated by the Spanish traceability program (SIMOGAN) for animal breeding purposes in the Pirenaica beef cattle breed. The traits included in the study were: cold carcass weight (CW, n = 20,010), conformation (CON, n = 15,808), fat cover (FC, n = 13,739) and colour (COL, n = 3477) from the SIMOGAN database; and weaning weight (WW, n = 15,561) from the Breeders Association (CONASPI) database. Posterior marginal estimates of genetic parameters were obtained using Bayesian inference, implemented via a Gibbs sampling scheme. Posterior marginal means of heritabilities were 0.34, 0.28, 0.19, 0.23 and 0.38 for CW, CON, FC, COL and WW, respectively. Moreover, posterior marginal distributions of genetic correlations between CW-CON, CW-WW, CON-FC and FC-WW do not include the zero within the Highest Posterior Density (HPD) at 95%, and their posterior mean estimates were 0.30, 0.54, − 0.35 and 0.23, respectively. These results indicate that there is enough genetic variability for selection in CW, CON, FC, COL and WW. The availability of records is potentially abundant at a very low cost, thus they can be easily included in the selection criteria. Consequences of the current selection criteria (WW) and other possible alternatives are discussed.     

Do Muscle Activities of M. Splenius and M. Brachiocephalicus Decrease Because of Exercise-Induced Fatigue in Thoroughbred Horses?

Muscle activities of the major hindlimb muscles have been reported to decrease with fatigue in horses. However, those in other muscles have been scarcely reported. We aimed to quantify fatigue-induced electromyographic changes in head and neck muscles and muscles around the shoulder joints in horses. Surface electromyographic recording of the splenius, brachiocephalicus, infraspinatus, and deltoid muscles was performed on a total of nine healthy Thoroughbred horses. Horses galloped on a treadmill inclined to 3% at a constant speed (12.7–14.6 m/second) to make them fatigued after approximately 5 minutes. They trotted at 3.5 m/second before and after this exercise. Stride frequency, integrated electromyographic values for a stride, and median frequency of the muscle discharge were calculated every 30 seconds. These parameters were compared at the start and end of the gallop exercise for the lead and trailing limbs and while trotting before and after the exercise using a paired t-test. The stride frequency significantly decreased at the end of the gallop (P < .001), whereas it did not change while trotting. Integrated electromyographic values of the splenius and brachiocephalicus muscles in both lead and trailing limbs at the gallop and those of both left and right sides at the trot significantly decreased with fatigue (P < .05), whereas those of infraspinatus and deltoid muscles did not change at either gallop or trot. No changes were observed in median frequency in any muscles with fatigue. These results suggest that splenius and brachiocephalicus muscle activities can be associated with stride frequency and speed.     

Recombinant Strain A/HK/Otar/6:2/2010 (H3N8) for Development of a Live Intranasal Equine Influenza Vaccine

Recombinant cold-adapted strain A/HK/Otar/6:2/2010 (H3N8) constructed by the method of classic genetic reassortment, inherited the hemagglutinin and neuraminidase genes from the epizootic A/equine/Otar/764/2007 (Н3N8) virus and genes of nonglycosylated proteins from attenuation donor A/Hong Kong/1/68/162/35 (H3N2). The resulted virus was of cold-adapted (efficient growth at 25°C) and temperature-sensitive (restricted replication at 39°C) phenotype. Like the parental virus of subtype H3N2, the resulted reassortant was attenuated, with limited replication in lungs of mice (1.75 lgEID₅₀/mL) versus replication in turbinate (2.5 lgEID₅₀/mL). Intranasal immunization of mice with A/HK/Otar/6:2/2010 (H3N8) reassortant did not induce animal weight reduction in contrast to epizootic A/equine/Otar/764/2007 (Н3N8) virus.