Evaluation of the sexual dimorphism in Mangalarga Marchador horses using discriminant analysis

This study used discriminant analysis to evaluate body measures and sexual dimorphism in Mangalarga Marchador horses. Discriminant analysis is a multivariate method that generates functions to classify animals using a prior criterion. In this study a prior criterion is male or female. The study analyzed 25 linear and 11 angular measures obtained from 25 stallions and 56 mares registered with the Mangalarga Marchador Brazilian Breeders Association. Knee girth, cannon girth, chest width, chest girth, back-loin length, hip width, distance from elbow to knee, hind limb hoof length, head width, shoulder length, and body length were found to be linear measures that provided evidence of sexual dimorphism. Angular measures with evidence of sexual dimorphism were shoulder–humerus, metacarpal–phalanx, coxae–femur, and femur–tibial angles. Stallions were larger than mares for almost all linear measures, except for back-loin length, hip width, and distance from elbow to knee. Shoulder–humerus and coxal–femur angles were larger in mares, while metacarpal–phalanx and femur–tibial angles were larger in stallions. Using linear measures, two mares were classified as stallions and three stallions were classified as mares. For angular measures, two other mares were classified as stallions and three other stallions were classified as mares. The discriminant functions can be useful for the selection of horses and to avoid registration of animals not meeting the phenotypic standards of the breed association.     

Analysis of the prevalence of pastern dermatitis in German Coldblood horse breeds

The prevalence of pastern dermatitis was investigated in 917 German Coldblood horses aged 2.5 to 26 years. Pastern dermatitis was prevalent in Black Forest Draught horses with 47.5% and in South German Draught horses with 58.5%. High prevalences were found in Mecklenburg (76.4%), Saxon-Thuringa (84.3%), Schleswig (86.0%), and Rhenisch German Coldblood (96.1%) horses. All four legs or both hind legs were affected most frequently. The most prevalent forms of pastern dermatitis were crusted and hyperkeratotic-hyperplastic. The occurrence of pastern dermatitis was dependent of age. The statistical analysis using a generalized linear model and a probit function showed the significant influence of the breed, age at examination, sex, position of the leg, interaction of breed by age at examination, and breed by position of the leg. So the analysis indicated that pastern dermatitis is a serious problem in all German Coldblood breeds investigated here.     

Estimation of genetic parameters of conformation traits in Iranian Thoroughbred horses

The aim of this study was to estimate the genetic parameters of conformation traits in Iranian Thoroughbred race horses. The data set included the conformation records of 607 Thoroughbred horses. In this study, 10 conformation traits were recorded. The effect of sex was significant for length of back line (P < 0.05), withers height (P < 0.05), circumference of front cannon (P < 0.001), and circumference of hind cannon (P < 0.001). The effect of age was significant for all traits (P < 0.01). The genetic parameters were estimated by the restricted maximum likelihood (REML) method using DFREML program. The heritability estimates were for head length 0.39, length of back line 0.41, length of shoulder 0.24, heart girth 0.49, chest width 0.22, withers height 0.38, front cannon height 0.27, circumference of front cannon 0.30, hind cannon height 0.29 and circumference of hind cannon 0.34. The estimates of genetic correlation ranged from 0.18 to 0.96 and those of phenotypic correlation varied from 0.16 to 0.83.     

伊犁马速步赛成绩与体尺性状的相关性研究

试验对伊犁马速步赛的体尺性状与比赛成绩之间的相关性进行了研究。测定速步赛中不同比赛项目伊犁马的体高(X₁)、体长(X₂)、胸围(X₃)和管围(X₄),计算体长率(X₅)、胸围率(X₆)和管围率(X₇),并用SPSS 18.0软件分析其与比赛成绩之间的相关性。结果表明,在不同的比赛项目中,体尺性状与比赛用时有显著或极显著的相关性(P<0.05;P<0.01)。1000 m速步赛中比赛用时随体高、体长、胸围的增大而减少,随管围、胸围率和管围率的减小而减小;3000 m速步赛中比赛用时随体高、体长的增大而减小,随胸围率和管围率的减小而减小;5000 m速步赛中比赛用时随体高、胸围、体长的增大而减小,随管围率的减小而减小。     

Verrucous pastern dermatitis syndrome in heavy draught horses. Part II: Clinical findings

In the present field study the skin of the feet of 37 heavy draught horses of different breeds showing verrucous pastern dermatitis was examined clinically. Included were the degree of severity of the disease and the prevalence of anatomically normal structures associated with the skin: fetlock tufts of hair ("feathering"), ergots, chestnuts, bulges in the pastern region, cannon circumference. Each horse was examined for Chorioptes sp. skin mites. Information was also collected on the development of the skin alterations and housing conditions and feeding. These individual data were correlated with the clinical degree of severity of verrucous pastern dermatitis, which was evaluated using a numerical code (scoring system). In addition, punch biopsies were taken from the diseased skin of the feet and from healthy skin of the neck for comparative patho-histological examination (see Part III). Verrucous pastern dermatitis is a chronic disease which can be divided into four groups: scaling (group I), hyperkeratotic and hyperplastic plaque-like lesions (group II), tuberous skin masses (group III), and verrucous skin lesions with rugged surfaces (group IV). No correlation was found between the clinical degree of severity of the skin lesions and sex, breed, amount of work, use of stallions for breeding, grooming condition of the hair, white markings in the foot region, or Chorioptes sp. infestation. In regard to feeding it was found that the amount of maize and oats fed had some influence on the clinical degree of severity. Statistical analysis revealed a significant correlation between the clinical degree of severity and the age, the grooming condition of the hooves, and the mean cannon circumference. The prevalence of fetlock tufts of hair, chestnuts, ergots, and anatomically normal bulges in the pastern region also increased significantly with the clinical degree of severity. Furthermore the study revealed that the clinical degree of severity depended on the hygienic conditions of the stables and of the ground where the horses were kept outdoors.     

Leptin secretion in horses: effects of dexamethasone, gender, and testosterone

Five experiments were performed to evaluate the effects of dexamethasone (DEX), gender, and testosterone on plasma leptin concentrations in horses. In experiment 1, plasma leptin, insulin, glucose, and IGF-1 concentrations were increased (P < 0.01) in stallions following five daily injections of DEX (125 microg/kg BW). In experiment 2, leptin concentrations increased (P < 0.01) in mares, geldings, and stallions following a single injection of DEX, and the response was greater (P < 0.01) in mares and geldings than in stallions. The gender effect was confounded by differences in body condition scores and diet; however, based on stepwise regression analysis, both BCS and gender were significant sources of variation in the best fit model for pre-DEX leptin concentrations (R(2) = 0.65) and for maximum leptin response to DEX (R(2) = 0.75). In experiment 3, in which mares and stallions were pair-matched based on age and body condition and fed similar diets, mares again had higher (P < 0.01) leptin concentrations than stallions after DEX treatment as used in experiment 2. In experiment 4, there was no difference (P > 0.1) in plasma leptin response in mares following four single-injection doses of DEX from 15.6 to 125 microg/kg BW. In experiment 5, treatment of mares with testosterone propionate every other day for 5 days did not alter (P > 0.1) plasma leptin concentrations or the leptin response to DEX. In conclusion, multiple injections of DEX increase leptin concentrations in stallions, as does a single injection in mares (as low as 15.6 microg/kg BW), geldings and stallions. The greater leptin levels observed in mares and geldings relative to stallions were due partially to their greater body condition and partially to the presence of hyperleptinemic individuals; however, even after accounting for body condition and diet, mares still had greater leptin concentrations than stallions after DEX administration. Elevation of testosterone levels in mares for approximately 10 days did not alter leptin concentrations in mares.     

Frequency of the severe combined immunodeficiency disease gene among horses in Morocco

Severe combined immunodeficiency disease (SCID) of horses is an autosomal, recessive hereditary disease occurring among Arabian or crossbred Arabian horses. The genetic defect responsible was previously identified as a 5‐base pair deletion in the gene encoding the catalytic subunit of the DNA dependant protein kinase (DNA‐PKcs). This study was carried out to determine the frequency of SCID and identify horses carrying the gene for SCID among Arabian and Arabian crossbred stallions and mares in Morocco using a DNA‐based test. Twenty‐one horses were SCID carriers: 14 (7%) Arabians, 6 (4%) Arab‐Barbs and one (3.3%) Anglo‐Arab. After analysing their genealogy, 3 imported stallions were identified that disseminated the mutant gene of DNA‐PKcs in Morocco.     

The development of verrucous pastern dermatitis syndrome in heavy draught horses. Part I: Review of the literature

Verrucous pastern dermatitis is a chronic hyperplastic dermatopathy of the feet of horses which is characterized by a greasy, odorous coating of the skin and, in advanced stages, by clearly demarcated calluses and wart-like proliferations. The disease occurs almost exclusively in cold-blooded and other heavy horses, with certain breeds affected most frequently. It is considered a distinct disease entity within the framework of pastern dermatitis syndrome. There is no consensus in the literature about relationship of the disease to the sex and age of the horse. Horses with a high cannon circumference and pronounced fetlock tufts of hair seem to be affected most severely. In chiefly anecdotal reports the cause of the disease or its aggravation has been ascribed to housing conditions and environmental influences, chemicals, mechanical insults, feeding, or infections with Chorioptes skin mites. It thus seems likely that the disease is affected by a variety of factors. Although verrucous pastern dermatitis has been known for hundreds of years, its etiology and pathogenesis remain unclear.     

Apparent adiposity assessed by standardised scoring systems and morphometric measurements in horses and ponies

This study described a scoring system for the assessment of apparent neck adiposity and evaluated morphometric measurements for assessment of neck and overall adiposity. Twenty-one barren Thoroughbred mares, 13 Arabian geldings and 75 Welsh, Dartmoor, or crossbred pony mares, were clinically examined and blood samples analysed for insulin, glucose, leptin, and triglycerides. Bodyweight (BW), height, length, girth and abdominal circumferences, neck length, neck crest height and neck circumference were measured, and body condition scores (BCS) and cresty neck scores (CNS) were rated. Girth:height ratio had the strongest associations with BCS (r(s)=0.64, P<0.001 in horses; r(s)=0.83, P<0.001 in ponies) and blood variables, such as leptin (r(s)=0.39, P=0.024 in horses; r(s)=0.68, P<0.001 in ponies). Crest height and neck circumference:height ratio had the strongest association with CNS (r(s)>0.50, P<0.01) and blood variables, such as insulin (r(s)0.40, P<0.05). Cresty neck score was useful in the assessment of neck crest adiposity and had physiological relevance, as demonstrated by associations with blood variables. Girth:height was the most suitable morphometric for assessment of overall adiposity, and either crest height or neck circumference:height was a suitable morphometric for assessment of apparent neck adiposity.     

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.     

A Preliminary Study Examining the Digital Cushion in Horses

The digital cushion is important for the dissipation of impact as the foot contacts the ground. If there is inefficient energy dissipation, potential exists for changes to occur in the foot. Although ultrasonic imaging of the digital cushion has been reported, it is unknown if these measurements account for compositional changes that have been reported across age, breed, and between fore and hind feet. Therefore, the objective of this preliminary study was to establish baseline values in mature, stock type horses with adequate body condition score (BCS). To meet this objective, 24 mature, stock-type horses of similar age, height, and weight were used to establish baseline values for the digital cushion thickness in the live horse. All horses were sound at the time of data collection and had no known history of long-term lameness conditions. Digital cushion thickness of the left fore and left hind foot was determined using ultrasound through the transcuneal approach. Data were analyzed using the PROC MEANS and PROC GLM procedure of SAS with a least square means statement. Significance was set at P ≤ .05. Mean values (±standard error [SE]) for age, weight, height, and BCS were 10.7 ± 0.86 years, 476.2 ± 7.75 kg, 153.56 ± 0.90 cm, and 5.6 ± 0.12, respectively. Mean values (±SE) for the digital cushion of the left fore and left hind were 0.96 ± 0.03 and 1.02 ± 0.04 cm, respectively. When comparing the left fore and left hind, there was no significant difference observed. Overall, baseline values of digital cushion thickness for fore and hind feet were established, allowing for future studies to assess the different variables known to affect digital cushion composition.     

Assessment of inbreeding depression for body measurements in Spanish Purebred (Andalusian) horses

Our aim was to ascertain inbreeding depression in the Spanish Purebred horses for eight body measurements. A total of 16,472 individuals were measured for height at withers, height at chest, leg length, body length, width of chest, heart girth circumference, knee perimeter and cannon bone circumference. Three different multivariate animal models including, respectively, no measure of inbreeding, individual inbreeding coefficients (F_i) or individual increase in inbreeding coefficients (ΔF_i) as linear covariates were used. Significant inbreeding depression was assessed. Even though the models including measures of inbreeding fitted better with data, no effect on estimates of genetic parameters was assessed. However, the inclusion of inbreeding measures affected the ranking order according to the Expected Breeding Values (EBV). Due to the better fit with data and nice properties (the adjustment of individual inbreeding coefficients with the pedigree depth and linear behaviour) the use of ΔF_i in the evaluation models can be recommended for morphological traits in horses.     

Daily treatment of horses with equine somatotropin from 4 to 16 months of age.

Fourteen foals between 4 and 4.5 mo of age were used to determine the effects of 12 mo of daily treatment with equine somatotropin (eST) on growth, metabolic, and hormonal characteristics. The foals were paired by sex, type, and lineage, and one of each pair was administered eST daily at 20 microg/kg of BW. Body weights, body measurements, and assessments of glucose tolerance and feedback effects on endogenous somatotropin (ST) secretion were made routinely. Treatment with eST did not alter (P > 0.10) BW, height at withers, length of body, widths of chest and rump, heart girth, length of head, front or rear cannon lengths, front or rear cannon circumferences, gaskin circumference, or skin thickness, even though plasma IGF-I concentrations were doubled (P = 0.012). Glucose concentrations were higher (P = 0.03) in treated horses before glucose infusion; there was no difference (P > 0.10) in the glucose response to infusion. The insulin response to glucose infusion in the treated horses was generally higher (P = 0.0069) than in controls. Endogenous ST secretion in response to a ST secretagogue was reduced (P = 0.0001) in foals treated with eST in all months. The prolactin and thyroid-stimulating hormone responses to thyrotropin-releasing hormone on June 1 were not affected (P > 0.10) by treatment. In conclusion, daily treatment of growing horses with eST for 12 mo at the recommended dose altered the hormonal and metabolic characteristics known to be affected by ST but did not alter the growth characteristics of the animals.     

Factors associated with the risk of developing sarcoid tumours in horses.

A retrospective case-control study was conducted to identify risk factors in horses associated with the development of the common skin tumours known as sarcoids. The study involved 503 sarcoid cases diagnosed (January 1980-December 1989) at New York State College of Veterinary Medicine and a similar number of controls (non-sarcoid cases). Data on age, breed and sex of cases and controls were obtained from computerised records. Multiple logistic regression analysis was used to identify risk factors. Separate data were obtained for the same 10-year period from the Veterinary Medical Data Program to determine the proportional morbidity rate at different veterinary colleges in North America. Appaloosa, Arabian and Quarter horses were at a higher risk of developing sarcoid tumours than were Thoroughbred horses. Standardbred horses had a lower risk of developing sarcoids. Geldings were at a higher risk of developing sarcoids in comparison with stallions. There was no significant difference in the risk of developing sarcoids between stallions and mares. The risk of developing sarcoid increased with age up to 15 years and then declined. The proportional morbidity rate of sarcoids among the veterinary colleges ranged between 0 and 14 per 1,000 cases, with an average of 6 per 1,000.     

Body measurements of newborn calves and relationship of calf shape to sire breeding values for birth weight and calving ease

Body measurements on Angus- (n = 374) and Polled Hereford-sired (n = 438) calves were used to quantify calf shape via multivariate factor analysis, and measurements on Polled Hereford-sired calves were further used to investigate relationships between calf shape and sire expected progeny differences (EPD) for birth weight and first-calf calving ease. Calf birth weight, head circumference, shoulder width, hip width, heart girth, cannon bone circumference and length, and body length were recorded at 24 h postpartum. Sire birth weight EPD was positively associated (P less than .05) with all calf measures but only with head and cannon circumference after adjustment for phenotypic birth weight and gestation length. Thus, at constant birth weight, calves from higher birth weight EPD bulls tended to have larger cannon and head circumferences. Calving ease EPD was negatively related (P less than .05) to all calf measures except shoulder width. After adjustment for birth weight, only cannon circumference was associated with calving ease EPD, and this effect was removed by additional adjustment for birth weight EPD. Thus, at constant birth weight, bulls with higher EPD for calving ease sired calves with smaller cannon circumference, but at constant birth weight EPD, body measures were not associated with calving ease EPD. Factor analysis defined underlying skeletal width and frame components of shape (independent of birth weight) for both sire breeds. Calf shape differed among sires and was in part explained by birth weight EPD. No additional variation in shape was explained by calving ease EPD. Calf shape seemed to add no information for prediction of dystocia to that provided by birth weight EPD.     

Phenotypic Correlations of Stride Traits and Body Measurements in Lipizzaner Stallions and Mares

Besides being well known for their use in classical dressage, Lipizzaner horses are today becoming more and more popular for use in driving sport, with Croatia as the largest breeder in the world. To estimate their phenotypic predisposition for driving sport, this research analyzes the correlation between body measurements and traits of length and speed of walk and hand-led trot in 18 stallions (LS) and 53 mares (LM) by using a digital camera. Statistical analysis of the data concerning phenotypic correlations among the indicated traits has revealed the potential of documenting a large number of structural exterior body characteristics and quantitative measurements in Lipizzaner horses, and technical equipment has been found to be useful in research of stride traits. Higher withers height (WH) achieved through breeding was found to be negatively correlated with the number of strides per second during walk and trot, but positively correlated with walk stride length, especially in LS. Higher values for chest girth (CG) and cannon bone circumference (CBC) were found to be positively correlated with speed, as well as with stride length in LS, and negatively correlated with the number of strides per second during walk and trot in both LS and LM. Because for many years the goal of breeding Lipizzaners in Croatia has been to obtain a bigger body format and longer stride, leading to better results in a driving sport, these findings confirm breeding goals in selection work guided toward better stride length and extended stride as the most desirable traits for driving sport.     

Effect of age on immunocytochemical staining characteristics of adenohypophyseal cells in Mongolian pony mares and stallions

OBJECTIVE: To determine the effect of age on immunocytochemical staining characteristics of adenohypophyseal cells of Mongolian pony mares and stallions. ANIMALS: 35 Mongolian ponies. PROCEDURE: Pituitary glands from 1- to 22-year-old horses of both sexes were collected at a commercial slaughterhouse in China and allocated into 7 groups according to age and sex: prepubertal stallions (n = 5; 1 to 2 years old), young stallions (6; 3 to 7 years old), middle-aged stallions (4; 10 to 12 years old), old stallions (5; 15 to 22 years old), young mares (3; 3 to 7 years old), middle-aged mares (5; 10 to 12 years old), and old mares (7; 15 to 22 years old). Pituitary glands were processed for microscopy, and sections were immunocytochemically stained for various pituitary hormones. The percentages and cell areas of 6 types of adenohypophyseal cells were determined by use of morphometry. RESULTS: Age-related alterations in adenohypophyseal cells were detected in horses > 15 years old. Percentage of somatotrophs decreased with age regardless of sex, and percentage of lactotrophs increased with age in stallions. In old mares, percentage of follicle-stimulating hormone cells increased, whereas cell area of follicle-stimulating hormone and luteinizing hormone cells decreased. Differences between sexes for percentage of somatotrophs and lactotrophs, and cell area of follicle-stimulating hormone and luteinizing hormone cells were not evident in old horses. CONCLUSIONS AND CLINICAL RELEVANCE: Differences among percentages and cell areas of pituitary cell types in old horses may be associated with degeneration of the sex organs.     

青海加什科羊体尺指标的测定

对加什科村的99只成年公羊、24只周岁公羊,82只成年母羊和47只周岁母羊的体高、体长、胸围、胸深和管围等体尺指标进行了测定。结果表明,加什科羊除体高和管围比青海细毛羊小外,其他三项体尺均大于青海细毛羊。与青海半细毛羊比较,胸围和管围小于青海半细毛羊,其他三项体尺均大于青海半细毛羊。周岁母羊的体高和胸深稍大于青海半细毛羊,而体长、胸围和管围均大于青海半细毛羊。     

Body measurements of crossbred calves sired by Simmental bulls divergently selected for progeny first-calf calving ease in relation to birth weight

Simmental bulls (n = 27) were divergently selected on linear model first-calf calving ease expected progeny difference (CEPD) relative to birth weight expected progeny difference (BEPD) so that body measures of calves from sires whose progeny tended to be born either with more or less dystocia than expected from BEPD could be obtained. At birth, calf weight, head circumference, shoulder width, hip width, heart girth, cannon bone circumference and length, and body length were recorded for 204 calves. These measures had also been obtained from the Polled Hereford X Angus dams of the calves at their births. Sire differences (P less than .05) existed for calf cannon bone circumference and length before and after adjustment for gestation length and birth weight of the calf. Sire BEPD was positively associated with cannon and head circumferences independent of phenotypic birth weight and gestation length. No relationship existed between CEPD or threshold model first-calf calving ease expected progeny difference and any calf measure, either before or after adjustment for birth weight. Multivariate factor analysis was used to describe independent components of skeletal width, frame, and thickness after removal of birth weight effects; factors were not related to genetic merit for calving ease or observed calving performance. Independent of weight, newborn calf measures were not highly related to body measures at weaning or to dam birth measures. Body shape differences at constant weight existed in crossbred calves, but they were not related to sire genetic merit for calving ease or measured dystocia. Selection for calf body shape, independent of birth weight, would not reduce dystocia.     

Longitudinal growth analysis of horses following limited and ad libitum feeding

Eighteen colts were assigned to one of two groups: limit or ad libitum feeding. Three periods were evaluated: 1) six to 12 months, 2) 12 to 18 months and 3) 18 to 24 months of age. At 24 months of age, ad libitum fed horses weighed 13 per cent (51 kg) more and were 3.6 per cent (5.2 cm) taller than those fed limited amounts. Total, fore and hind body mass increased quadratically irrespective of dietary treatment. Fore body mass comprised 57 per cent of total body mass for both groups and this did not change with age or dietary treatment. Heart girth was directly related (R2 = 0.96) to total body mass. Average daily gains in total body mass of ad libitum fed horses were 13 and 71 per cent more rapid (P less than 0.05) than for limit fed horses in Periods 1 and 3, respectively. Ad libitum fed horses gained hind body mass 25 per cent more rapidly (P less than 0.05) than limit fed horses only in Period 1. Growth curves of wither and croup heights were quadratic in form. Ad libitum fed horses gained 12 and 13 per cent more rapidly at the wither than limit fed horses in Period 1 and overall, respectively. Ad libitum fed horses grew 33 per cent more rapidly at the croup than limit fed horses but only in Period 2. From six to 12 months of age, the wither and croup grew two-fold and four-fold more rapidly than between 12 to 18 months and between 18 to 24 months of age, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)