Analysis of founders and performance test effects on an autochthonous horse population through pedigree analysis: structure, genetic variability and inbreeding.

The Maremmano is an autochthonous Italian horse breed, which probably descended from the native horses of the Etruscans (VI century B.C.); the Studbook was acknowledged in 1980, and it includes 12 368 horses born from that year up to 2015. The aim of this study was to evaluate the effect of the selection program on the genetic variability of the Maremmano population; the analysis was performed using both the 'Endog v 4.8' program available at http://webs.ucm.es/info/prodanim/html/JP_Web.htm and in-house software on official pedigree data. Four Reference Populations were considered, and the most important one was the population of the 12 368 Maremmano horses officially registered in the National Studbook. The pedigree completeness of this population was very good because it was more than 90% at the third parental generation and more than 70% at the fifth generation; the pedigree traced back to a maximum of 10.50 generations with an average of 3.30 complete generations and 5.70 equivalent complete generations. The average generation interval was 10.65±4.72 years, with stallions used for longer periods than mares. The intervals ranged from 10.15±4.45 (mother-daughter) to 10.99±4.93 (father-daughter). The effective number of founders (f e) was 74 and the effective number of ancestors (f a) was 30 so that the ratio f e/f a was 2.47. The founder genome equivalents (f g) was 13.72 with a ratio f g/f e equal to 0.18. The mean of the genetic conservation index was 5.55±3.37, and it ranged from 0.81 to 21.32. The average inbreeding coefficient was 2.94%, with an increase of 0.1%/year, and the average relatedness coefficient was 5.52%. The effective population size (N e) computed by an individual increase in inbreeding was 68.1±13.00; the N e on equivalent generations was 42.00, and this value slightly increased to 42.20 when computed by Log regression on equivalent generations. The analysis confirmed the presence of seven traditional male lines. The percentage of Thoroughbred blood in the foals born in 2015 was 20.30% and has increased 0.21%/year since 1980; in particular, it increased more than twice (0.51%/year) until 1993 and afterwards slightly fluctuated. The pedigree analysis confirmed the completeness of genealogical information and the traditional importance that breeders gave to the male lines; although the genetic diversity of Maremmano seemed to be not endangered by the selection program, some effects on the population structure were found and a more scientific approach to genetic conservation should be incorporated in the selection plans.

Pharmacokinetics and tolerability of a new formulation of omeprazole in the horse.

A new formulation of omeprazole in gastro-resistant granules was tested with regard to its pharmacokinetics and tolerability. Twenty-four horses were randomly divided into three groups (8 horses/group) and treated, according a parallel study design, as follows: Group A untreated (control group), Group B received 4 mg/kg of omeprazole, and Group C received 12 mg/kg of omeprazole, both of which were treated orally once a day for 90 days. Blood samples, taken from Group B subjects during the 1st and the 29th day of treatment at pre-established time points, were used to determine the concentration-time curves of omeprazole. The treatments were found to be safe and well tolerated by the horses. The serum hematological and biochemical values were within reference ranges for the entire observational time. No accumulation of the drug was found after 29 days of treatment. Lower Cmax and AUCs were obtained at the 29th day of treatment.

Influence of single nucleotide polymorphisms in the myostatin and myogenic factor 5 muscle growth-related genes on the performance traits of Marchigiana beef cattle.

The Marchigiana is famous for its large body size and favorable dressing percentage. A myostatin (MSTN) gene mutation (a G to T transversion) was identified in the breed. The homozygote "GG" yields a "normal" phenotype, the homozygote "TT" yields a double muscled body shape but sometimes causes survival problems, and the heterozygote genotype produces an extremely muscled body without defects. In practice, Marchigiana "TT" homozygotes are culled from reproduction, but the heterozygotes are chosen as sires. The objective of this study was to assess genes involved in Marchigiana muscle development to improve selection procedures. The effects of the MSTN and myogenic factor 5 (MYF5) genes on the growth and muscle traits in the Marchigiana breed were assessed. The effects of MSTN together with the genotype of the causative mutation (g.874G > T) and the effects of the two SNP in the promoter were studied (g.-371T > A and g.-805G > C). The SNP effects were evaluated in a comparison between the means of the several genotypes or for the average gene substitution and dominance effect. Two hundred forty-nine bullocks were evaluated using a performance test. At the beginning and end of the trial, the animals were weighed and their bodies were measured every 21 d up to 12 mo of age. In addition to these observations, morphological scores and the BLUP indices were estimated at the end of the performance test. The obtained results suggested that the MSTN g.874G > T and MYF5 SNP could be considered in the selection program of the Marchigiana breed. A MSTN g.874G > T genotyping service for the breeders could help to avoid the "TT" genotype and to select for the "GT" genotype. The "AA" MYF5 SNP genotype could also be selected for even if good muscle development yields a certain size reduction.

Genetic parameters for the weights and yields of carcass cuts in Chianina cattle.

Chianina is the tallest and heaviest beef cattle breed in the world and 1 of the most appreciated breeds on the Italian meat market. A selection program focused on improving Chianina carcass quality could provide a further economic advantage to Chianina breeders. However, the current European carcass scoring system [i.e., the SEUROP (S=superior, E=excellent, U= very good, R=good, O=fair, and P=poor) grid] is not suitable for use in selective breeding programs; methods based on carcass cuts would be much more efficient. Here, the genetic parameters of weights and yields (percentage of carcass weight) of the main commercial cuts were estimated on 842 Chianina carcasses (heifers and bullocks) using a mixed model that takes into account the fixed effects of herd, year of slaughter, and sex and the random additive effect of the animal; the carcass weight was also considered in cuts yield. The average carcass weights were 492.6 ± 86.52 kg (males) and 312.1 ± 68.74 kg (females), and the largest cut was the round, with a weight of 58.6 ± 19.35 kg and yield of 24.4 ± 1.28% in males and 40.2 ± 17.59 kg and 25.3 ± 1.41% in females. The variability in cut weight was greater than that in yield percentage. The cut weight heritabilities ranged from 0.74 (chuck) to 0.21 (short plate) whereas the yield heritabilities ranged from 0.88 (loin) to 0.40 (brisket). The genetic correlations were generally high and positive between weights; correlation values with yields were lower and could be positive or negative. These findings suggest that a selection program to improve the carcass quality of Chianina beef using cuts data could potentially achieve good results.

Using eigenvalues as variance priors in the prediction of genomic breeding values by principal component analysis.

Genome-wide selection aims to predict genetic merit of individuals by estimating the effect of chromosome segments on phenotypes using dense single nucleotide polymorphism (SNP) marker maps. In the present paper, principal component analysis was used to reduce the number of predictors in the estimation of genomic breeding values for a simulated population. Principal component extraction was carried out either using all markers available or separately for each chromosome. Priors of predictor variance were based on their contribution to the total SNP correlation structure. The principal component approach yielded the same accuracy of predicted genomic breeding values obtained with the regression using SNP genotypes directly, with a reduction in the number of predictors of about 96% and computation time of 99%. Although these accuracies are lower than those currently achieved with Bayesian methods, at least for simulated data, the improved calculation speed together with the possibility of extracting principal components directly on individual chromosomes may represent an interesting option for predicting genomic breeding values in real data with a large number of SNP. The use of phenotypes as dependent variable instead of conventional breeding values resulted in more reliable estimates, thus supporting the current strategies adopted in research programs of genomic selection in livestock.

Doppler evaluation of maternal and foetal vessels during normal gestation in queen.

The aim of this work is to evaluate the haemodynamic characteristics of maternal and foetal vessels during normal pregnancy in queens, using colour Doppler and pulsed wave Doppler ultrasonography, in order to obtain information about maternal and foetal circulation. The blood waveforms of the uteroplacental arteries, aorta, caudal cava vein and umbilical cord of the fetuses were recorded weekly in seven healthy pregnant queens. Also, the measurements of peak systolic, end diastolic velocities, resistance and pulsatility indices were carried out. Uteroplacental blood flow was biphasic while the ones of the umbilical artery and aorta were first systolic and then diastolic. The caudal cava vein showed a typical waveform of venous vessels. During gestation the EDV and PSV of foetal vessels increased (alpha<0.05) while the PI and RI of all vessels examined decreased (alpha<0.05) except for the IP of the aorta. The Doppler ultrasonography, also in queens, can be used to evaluate the characteristics of maternal and foetal vessel flow and their progressive changes during pregnancy. This study can be considered the basis for further contribution in diagnosing and monitoring high-risk pregnancies in Veterinary Medicine.

Seroepidemiological survey of Rhodoccocus equi infection in asymptomatic horses from Bursa, Izmir and Istanbul provinces, Turkey.

In order to assess the Rhodococcus equi infection in three provinces of Turkey (Bursa, Izmir and Istanbul), 696 sera from healthy foals and adult horses were tested by indirect ELISA using a R. equi reference strain (ATCC 6939) as antigen. 103 sera (14.80%) with titres >0.646 resulted positive. Seroprevalence was significantly higher (P=0.0053) in male than in female horses of Istanbul province, although higher antibody titres (mean value) were observed in the female group of Bursa and Izmir provinces with differences estimated between provinces (P=0.0002). Seroprevalence was correlated with age: foals aged less than 1 year (P<10(-4)) and horses from 5 to 10 years old (P=0.018) resulted more infected in Bursa and Izmir provinces. Our findings indicate that R. equi infection actually occurs in all investigated provinces, suggesting the importance of serological survey to diagnose the infection and to prevent the zoonotic risk.

A serological survey of Rhodococcus equi infection in foals in central Italy: comparison of two antigens using an ELISA test.

A serological survey of Rhodococcus equi infection was carried out on 602 blood samples collected from foals in central Italy. The assay was performed with an ELISA test using two different antigens prepared with reference strains of R. equi, ATCC 33071 and ATCC 6939. A positive reaction was obtained on 81 serum samples (13.45%) (OD > or = 0.3) using antigen ATCC 33071, and on 73 serum samples (12.12%) using antigen ATCC 6939. Although the frequency of the disease was not high, the serological positivity was about 13%. There was no statistically significant difference between males and females. The ELISA test using either Antigen 33071 or Antigen 6939 is a rapid and reliable tool for detecting antibodies against R. equi in foals.

Effect of genetic groups on estimates of additive genetic variance.

This study examined the effect of genetic grouping on REML estimates of additive genetic variance with an animal model with selected base populations. A simulated population of 40 animals (20 males and 20 females) was followed under selection or random mating conditions for 10 generations. Each population was replicated 20 or 50 times. Genetic grouping reduced estimates of additive genetic variance in populations with selected base animals, whereas grouping had little effect on the estimate in unselected populations. The effect of genetic grouping varied according to the quantity and kind of information that was missing (percentage of deleted data and pattern of deletion). When genetic grouping was completely random, the estimates were unaffected. Because including genetic groups in the model for analysis affected the estimates of additive genetic variance, the question should be considered of what value or values for heritability should be used for genetic evaluation when grouping is used to account for prior selection.