The aim of this study was to analyze LEP and DGAT1 gene polymorphisms in 3 Nelore lines selected for growth and to evaluate their effects on growth and carcass traits. Traits analyzed were birth, weaning, and yearling weight, rump height, LM area, backfat thickness, and rump fat thickness obtained by ultrasound. Two SNP in the LEP gene [LEP 1620(A/G) and LEP 305(T/C)] and the K232A mutation in the DGAT1 gene were analyzed. The sample consisted of 357 Nelore heifers from 2 lines selected for yearling weight and a control line, established in 1980, at the Estação Experimental de Zootecnia de Sertãozinho (Sertãozinho, Brazil). Three genotypes were obtained for each marker. Differences in allele frequencies among the 3 lines were only observed for the DGAT1 K232A polymorphism, with the frequency of the A allele being greater in the control line than in the selected lines. The DGAT1 K232A mutation was associated only with rump height, whereas LEP 1620(A/G) was associated with weaning weight and LEP 305(T/C) with birth weight and backfat thickness. However, more studies, with larger data sets, are necessary before these makers can be used for marker-assisted selection.

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-Data from 79,884 Nellore breed animals were used to estimate genetic parameters and to evaluate the relationships among scores of conformation, precocity and musculature obtained at weaning and after yearling ages and weight of mature females. It was used the restricted maximum likelihood method in a multi-trait analysis with the model that included direct additive genetic and residual effects, as random effects, and the fixed effects of contemporary group and, as covariables, animal age at weighing and age of dam at calving (except for weight of females at adult age). Contemporary groups at weaning were defined by the variables: sex, herd, year and month of birth, and management group at birth and weaning. For definition of contemporary group at yearling, it was also included the variable management group at yearling. For female weight at mature age, contemporary group was composed of herd, year of birth, management group at yearling, weighing year and season.Maternal genetic and maternal permanent environment effects were also included in the model for analyses of scores of conformation, precocity and muscularity at weaning. The direct herdability estimates obtained were the following: 0.18 ± 0.02 for conformation at weaning score, 0.21 ± 0.01 for precocity at weaning score, 0.22 ± 0.01 for muscularity at weaning score, 0.24 ± 0.01 for conformation at yearling score, 0.27 ± 0.01 for precocity at yearling score, and 0. Key Words: beef cattle, conformation, genetic correlation, musculature, precocity Análise genética de escores visuais e suas relações com o peso de fêmeas à idade adulta na raça Nelore RESUMO -Dados de 79.884 animais da raça Nelore foram utilizados para estimar parâmetros genéticos e avaliar as relações entre os escores de conformação, precocidade e musculatura obtidos à desmama e ao sobreano e o peso das fêmeas à idade adulta. Utilizou-se o método da máxima verossimilhança restrita, em análise multicaracterísticas, com modelo que incluiu os efeitos genéticos aditivos direto e residual, como aleatórios, e os efeitos fixos de grupo de contemporâneos e, como covariáveis, a idade do animal à pesagem e a idade da mãe ao parto (exceto para o peso das fêmeas à idade adulta). Os grupos contemporâneos à desmama foram definidos pelas variáveis: sexo, rebanho, ano e mês de nascimento, grupo de manejo ao nascimento e à desmama. Na definição de grupo contemporâneo ao sobreano também foi incluída a variável grupo de manejo ao sobreano. Para o peso das fêmeas à idade adulta, o grupo de contemporâneos foi composto por rebanho, ano de nascimento, grupo de manejo ao sobreano, ano e estação da pesagem. Os efeitos genético materno e de ambiente permanente materno também foram incluídos no modelo para análise dos escores de conformação, precocidade e musculatura à desmama. As estimativas de herdabilidade direta obtidas foram 0,18 ± 0,02 para o escore de conformação; 0,21 ± 0,01 para o escore de precocidade; 0,22 ± 0,01 para o escore de musculatura à desmama e 0,24 ± 0,01 para o escore de conformação; 0,27 ...

Reproductive traits are of the utmost importance for any livestock farming, but are difficult to measure and to interpret since they are influenced by various factors. The objective of this study was to detect associations between known polymorphisms in candidate genes related to sexual precocity in Nellore heifers, which could be used in breeding programs. Records of 1,689 precocious and non-precocious heifers from farms participating in the Conexão Delta G breeding program were analyzed. A subset of single nucleotide polymorphisms (SNP) located in the region of the candidate genes at a distance of up to 5 kb from the boundaries of each gene, were selected from the panel of 777,000 SNPs of the High-Density Bovine SNP BeadChip. Linear mixed models were used for statistical analysis of early heifer pregnancy, relating the trait with isolated SNPs or with haplotype groups. The model included the contemporary group (year and month of birth) as fixed effect and parent of the animal (sire effect) as random effect. The fastPHASE® and GenomeStudio® were used for reconstruction of the haplotypes and for analysis of linkage disequilibrium based on r2 statistics. A total of 125 candidate genes and 2,024 SNPs forming haplotypes were analyzed. Statistical analysis after Bonferroni correction showed that nine haplotypes exerted a significant effect (p<0.05) on sexual precocity. Four of these haplotypes were located in the Pregnancy-associated plasma protein-A2 gene (PAPP-A2), two in the Estrogen-related receptor gamma gene (ESRRG), and one each in the Pregnancy-associated plasma protein-A gene (PAPP-A), Kell blood group complex subunit-related family (XKR4) and mannose-binding lectin genes (MBL-1) genes. Although the present results indicate that the PAPP-A2, PAPP-A, XKR4, MBL-1 and ESRRG genes influence sexual precocity in Nellore heifers, further studies are needed to evaluate their possible use in breeding programs.

Monocarboxylate transporter isoform 1 (MCT1) and its ancillary protein, CD147 function to transport H þ and lactate ions, retarding systemic acidosis and fatigue. The PDK4 gene is involved in the adenosine triphosphate production, and the DMRT3 gene is involved in the locomotor system. This study investigated polymorphisms of MCT1, CD147, PDK4, and DMRT3 in Arabian and Quarter Horses to associate polymorphisms with performance. Arabian Horses were divided into high performance and untrained horses groups based on success in endurance competition, whereas Quarter Horses were separated by a speed index. Polymorphisms were analyzed by sequencing (MCT1 and CD147), ARMS-PCR (PDK4), and PCR-RFLP (DMRT3). To compare the frequencies of SNPs, the Fisher's exact test was performed in the software R at 5% of significance. The A alleles from the polymorphisms Lys457Gln:1573A>C of MCT1 and Ile51Val:168A>G of CD147 were essentially fixed in both breeds. Only two Arabian from the high performance and one from the untrained horses group appeared AC in MCT1. For the DMRT3 polymorphism (g.22999655C>A:ECA23), all the animals were CC, except one Arabian in the high and two Quarter Horses in the low performance group that were AC. For the PDK4 polymorphism (g.38973231A>G:ECA4), Arabian showed a significantly greater frequency of the G allele than Quarter Horses (P < .01). Considering the kind of exercise practiced by each breed, it is likely that the PDK4 polymorphism influences the pathway to energy production.

Horse owners choose whether or not to train American Saddlebred horses (ASHs) to perform the 4-beat gaits called rack and slow gait. The rack and slow gait are similar to ambling gaits shown to be associated with variation in the DMRT3 gene in other breeds but are trained rather than naturally occurring gaits. A premature stop codon in the DMRT3 gene (DMRT3_Ser301STOP) caused by the Ch23:g.22999655C>A SNP has an effect on the pattern of locomotion in horses and allows for the pacing gait and strong association with performance of ambling gaits in diverse breeds. We used horse show records to identify ASHs trained to perform as 5-gaited horses and compared them to other Saddlebreds for the prevalence of the A allele of the Ch23:g.22999655C>A SNP of DMRT3. Genomic DNA was typed using a PCR-RFLP technique for 5-gaited ASHs (n = 55), 3-gaited or harness ASHs (n = 64) and ASHs not shown (n = 128). We did not observe differences in the frequencies of the Ch23:g.22999655C>A SNP of DMRT3 when comparing 5-gaited ASHs to other ASHs (P > 0.22). These results suggest that DMRT3 alleles do not affect the choice of breeders to train and show ASHs as 5-gaited horses.

This publication is a compilation of all Research Abstracts presented at the Ninth International Conference on Equine Exercise Physiology. Unlike previous ICEEP conferences there will not be a conference proceedings of full length manuscripts. These abstracts succinctly summarise a wide array of investigations relevant to the equine athlete, and will be useful to veterinarians and others involved in management of horses used for sport, work and competition. The abstracts encompass the topics of Applied Physiology; Biochemistry, Haematology, Endocrinology, and Thermoregulation; Cardiovascular and Respiratory; Muscle and Bone; Nutrition; Genomics, Proteomics, and Metabolomics; Biomechanics and Locomotion; as well as Physiotherapy, Rehabilitation, and Equitation science.The International Committee of ICEEP publishes these abstracts so that the most recent scientific information is available to a wide audience, including veterinarians, physiotherapists, trainers, owners and riders.The Introduction:The ability to accurately assess equine oxygen consumption (VO2) under field conditions has been limited by the need for unrestricted gas exchange.Methods: Two variations of a mask and an associated electronics control module (ECM) were designed to enable breath-by-breath measurement of airflows with two 8.0 cm diameter pneumotachometers located 7.5 cm in front of each narus and connected to differential pressure transducers mounted on the outside of the mask. The ECM was comprised of electronics for signal filtering to the flow transducers, an oxygen sensing cell, and an analog-to-digital converter all powered by a lithium-ion battery. The battery also powered a pump connected to gas sampling ports between the nares and pneumotachometers. Airflow and oxygen content of inspired and expired gases were recorded through the ECM and electronically transferred to a notebook. VO2 was determined from these recordings by an operator using a customized software analysis program. One mask encased the lower head (E). The other left the jaw free so horse could wear a bit and be ridden (R). Multiple treadmill exercise tests were undertaken by 6 horses to measure VO2max and blood gases. Each mask was worn twice and results compared to those from an open flow-through system (O) by 2-way RMANOVA (P<0.05). Utility of the system was evaluated using the intraclass correlation coefficient of 4 independent raters.Results: Blood gases and VO2max (152.0 ± 4.0 (mean ± SEM; O), 147.7 ± 4.3 (E), 150.7 ± 3.3 (R) ml/(kg.min) were not different between masks. VO2 measures were reproducible for each mask. Agreement between the 4 raters was excellent (intraclass correlation coefficient = 0.99). Conclusions:Masks capable of measuring VO2 during field exercise were developed, tested and found accurate by multiple users.Ethical Animal Research: Studies performed were approved by the Institution's Animal Care and Use Committee (protocol #3807). Sources of funding: Institutional sources. Competing interests: Washington State University has filed notice of i...

The aim of this study was to determine the extent (r) of linkage disequilibrium (LD) in the genome of Nellore cattle, and to examine associations between single nucleotide polymorphisms (SNP) and age at first calving (AFC) and early pregnancy (EP) using a panel of high-density SNPs and data from 1182 Nellore females. A total of 13 contemporary groups (CG) were used consisting of farm, season, and year of birth. For genome-wide association analysis, SNPs with a minor allele frequency (MAF)<0.05 and animals with a call rate<0.90 were excluded, totaling 431,885 SNPs. For statistical analysis, a linear model was used for AFC and a threshold model for EP. To estimate the significance of the associations for the two traits, the model included the categorical fixed effects of CG, SNPs, and sire. In addition, the polygenic effect was included in the analysis. The additive effects and dominance deviations of Bonferroni-adjusted significant SNPs for AFC and EP were estimated using orthogonal contrasts. The average estimate of r for all autosomes was 0.18 at a distance of 4.8kb and the mean MAF was 0.25±0.13. The LD decreased as the distance between markers increased: 0.35 (1kb) to 0.12 (100kb). Eleven significant associations were detected in seven different chromosomes. Seven SNPs were associated with AFC and four were associated with EP. Three SNPs were significant for both traits. The identification of SNPs associated with AFC and EP may contribute for selecting sexually precocious animals.