MUC1 gene polymorphism in three Nelore lines selected for growth and its association with growth and carcass traits

The objective of this study was to describe the VNTR polymorphism of the mucin 1 gene (MUC1) in three Nelore lines selected for yearling weight to determine whether allele and genotype frequencies of this polymorphism were affected by selection for growth. In addition, the effects of the polymorphism on growth and carcass traits were evaluated. Birth, weaning and yearling weights, rump height, Longissimus muscle area, backfat thickness, and rump fat thickness, were analyzed. A total of 295 Nelore heifers from the Beef Cattle Research Center, Instituto de Zootecnia de Sertozinho, were used, including 41 of the control line, 102 of the selection line and 152 of the traditional. The selection and traditional lines comprise animals selected for higher yearling weight, whereas control line animals are selected for yearling weight close to the average. Five alleles were identified, with allele 1 being the most frequent in the three lines, especially in the lines selected for higher means for yearling weight. Heterozygosity was significantly higher in the control line. Association analyses showed significant effects of allele 1 on birth weight and weaning weight while the allele 3 exert significant effects on yearling weight and back fat thickness. Despite these findings, application of this marker to marker-assisted selection requires more consistent results based on the genotyping of a larger number of animals in order to increase the accuracy of the statistical analyses.

Manipulation of the periovulatory sex steroidal milieu affects endometrial but not luteal gene expression in early diestrus Nelore cows

In beef cattle, the ability to conceive has been associated positively with size of the preovulatory follicle (POF). Proestrus estradiol and subsequent progesterone concentrations can regulate the endometrium to affect receptivity and fertility. The aim of the present study was to verify the effect of the size of the POF on luteal and endometrial gene expression during subsequent early diestrus in beef cattle. Eighty-three multiparous, nonlactating, presynchronized Nelore cows received a progesterone-releasing device and estradiol benzoate on Day–10 (D 10). Animals received cloprostenol (large follicle-large CL group; LF-LCL; N ¼ 42) or not (small follicle-small CL group; SF-SCL; N ¼ 41) on D 10. Progesterone devices were withdrawn and cloprostenol administered 42 to 60 hours (LF-LCL) or 30 to 36 hours (SF-SCL) before GnRH treatment (D0). Tissues were collected at slaughter on D7. The LF-LCL group had larger (P < 0.0001) POF (13.24 0.33 mm vs. 10.76 0.29 mm), greater (P < 0.0007) estradiol concentrations on D0 (2.94 0.28 pg/mL vs. 1.27 0.20 pg/mL), and greater (P < 0.01) progesterone concentrations on D7 (3.71 0.25 ng/mL vs. 2.62 0.26 ng/mL) compared with the SF-SCL group. Luteal gene expression of vascular endothelial growth factor A, kinase insert domain receptor, fms-related tyrosine kinase 1, steroidogenic acute regulatory protein, cytochrome P450, family 11, subfamily A, polypeptide 1, and hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid deltaisomerase 7 was similar between groups. Endometrial gene expression of oxytocin receptor and peptidase inhibitor 3, skin-derived was reduced, and estrogen receptor alpha 2, aldo-keto reductase family 1, member C4, and lipoprotein lipase expression was increased in LF-LCL versus SF-SCL. Results support the hypothesis that the size of the POF alters the periovulatory endocrine milieu (i.e., proestrus estradiol and diestrus progesterone concentrations) and acts on the uterus to alter endometrial gene expression. It is proposed that the uterine environment and receptivity might also be modulated. Additionally, it is suggested that increased progesterone secretion of cows ovulating larger follicles is likely due to increased CL size rather than increased luteal expression of steroidogenic genes.

Estimation of taurindicine hybridization of American Zebu cattle in Brazil

Our objective was to estimate Bos primigenius taurus introgression in American Zebu cattle. One hundred and four American Zebu (Nellore) cattle were submitted to mtDNA, microsatellite and satellite analysis. Twenty-three alleles were detected in microsatellite analysis, averaging 4.6 +/- 1.82/locus. Variance component comparisons of microsatellite allele sizes allowed the construction of two clusters separating taurus and indicus. No significant variation was observed when indicus and taurus mtDNA were compared. Three possible genotypes of 1711b satellite DNA were identified. All European animals showed the same restriction pattern, suggesting a Zebu-specific restriction pattern. The frequencies of B. primigenius indicus-specific microsatellite alleles and 1711b satellite DNA restriction patterns lead to an estimate of 14% taurine contribution in purebred Nellore.

Trends of the genetic connectedness measures among Nelore beef cattle herds

Validity of comparisons between expected breeding values obtained from best linear unbiased prediction procedures in genetic evaluations is dependent on genetic connectedness among herds. Different cattle breeding programmes have their own particular features that distinguish their database structure and can affect connectedness. Thus, the evolution of these programmes can also alter the connectedness measures. This study analysed the evolution of the genetic connectedness measures among Brazilian Nelore cattle herds from 1999 to 2008, using the French Criterion of Admission to the group of Connected Herds (CACO) method, based on coefficients of determination (CD) of contrasts. Genetic connectedness levels were analysed by using simple and multiple regression analyses on herd descriptors to understand their relationship and their temporal trends from the 19992003 to the 20042008 period. The results showed a high level of genetic connectedness, with CACO estimates higher than 0.4 for the majority of them. Evaluation of the last 5-year period showed only a small increase in average CACO measures compared with the first 5 years, from 0.77 to 0.80. The percentage of herds with CACO estimates lower than 0.7 decreased from 27.5% in the first period to 16.2% in the last one. The connectedness measures were correlated with percentage of progeny from connecting sires, and the artificial insemination spread among Brazilian herds in recent years. But changes in connectedness levels were shown to be more complex, and their complete explanation cannot consider only herd descriptors. They involve more comprehensive changes in the relationship matrix, which can be only fully expressed by the CD of contrasts.

Assessment of field fertility and several in vitro sperm characteristics following the use of different Angus sires in a timed-AI program with suckled Nelore cows

In order to provide information that may help researchers to understand the main cause(s) of differences in bull fertility frequently observed in field trials, this study aimed to investigate conception rates as well as several in vitro sperm characteristics of different sires of unknown fertility utilized in a Timed-AI (TAI) program. Suckled Nelore cows submitted to the same TAI protocol were allocated into eight breeding groups of approximately 120 animals each. Frozen semen doses from three Angus bulls and three different batches from each bull were utilized. Approximately 100 doses from each batch were used in TAI. Sires, batches and AI technicians were equally distributed across breeding groups. Cows were examined for pregnancy diagnosis 40 d after TAI. For in vitro sperm analyses, the same thawing procedure was repeated in the laboratory to mimic field conditions. The following in vitro sperm characteristics were assessed: computerized motility, thermal resistance, plasma and acrosomal membrane integrity, lipid peroxidation, morphology, morphometry and chromatin structure. No effect of breeding group, body condition score, AI technician and sire was observed. However, some significant differences among bulls were detected in laboratory analyses. Semen from sire presenting numerically lower (P > 0.05) pregnancy/AI also presented lower (P < 0.05) values in all sperm characteristics analyzed in thermal resistance test at 4 h (Total Motility, Progressive Motility, Average Path Velocity, Straight-Line Velocity, Curvilinear Velocity, Amplitude of Lateral Head Displacement, Beat Cross Frequency, Straightness, Linearity, and Percentage of Rapidly Moving Cells), higher (P < 0.05) Major and Total Defects in sperm morphological test, lower (P < 0.05) Length, Ellipticity and Fourier parameter (Fourier 0) in sperm morphometric analysis as well as higher (P < 0.05) chromatin heterogeneity. It was concluded that, although no bull effect was observed in the field experiment, the sire that presented numerically lower pregnancy/AI also presented lower semen quality according to the laboratory analyses performed. (C) 2012 Elsevier B.V. All rights reserved.

Effect of sequence of insemination after simultaneous thawing of multiple semen straws on conception rate to timed AI in suckled multiparous Nelore cows

The objective was to determine the effect of sequence of insemination after simultaneous thawing of multiple 0.5 mL semen straws on conception rate in suckled multiparous Nelore cows. The effect of this thawing procedure on in vitro sperm characteristics was also evaluated. All cows (N = 944) received the same timed AI protocol. Ten straws (0.5 mL) of frozen semen from the same batch were simultaneously thawed at 36 degrees C, for a minimum of 30 sec. One straw per cow was used for timed AI. Frozen semen from three Angus bulls was used. Timed AI records included sequence of insemination (first to tenth) and time of semen removal from thawing bath. For laboratory analyses, the same semen batches used in the field experiment were evaluated. Ten frozen straws from the same batch were thawed simultaneously in a thawing unit identical to that used in the field experiment. The following sperm characteristics were analyzed: sperm motility parameters, sperm thermal resistance, plasma and acrosomal membrane integrity, lipid peroxidation, chromatin structure, and sperm morphometry. Based on logistic regression, there were no significant effects of breeding group, body condition score, AI technician, and sire on conception rate, but there was an interaction between sire and straw group (P = 0.002). Semen from only one bull had decreased (P < 0.05) field fertility for the group of straws associated with the longest interval from thawing to AI. However, the results of the laboratory experiment were unable to explain the findings of the field experiment. Sperm width:length ratio of morphometric analysis was the single sperm characteristic with a significant interaction between sire and straw group (P = 0.02). It was concluded that sequence of insemination after simultaneous thawing of 10 semen straws can differently affect conception rates at timed AI, depending on the sire used. Nevertheless, the effects of this thawing environment on in vitro sperm characteristics, remain to be further investigated. (C) 2012 Elsevier Inc. All rights reserved.

Oócitos aparentemente maduros injetados em telófase I apresentam piores resultados de reprodução assistida

OBJETIVO: Avaliar o estágio de maturação nuclear de oócitos com o primeiro corpúsculo polar (CP) visível de pacientes inférteis submetidas à estimulação ovariana para injeção intracitoplasmática de espermatozoide (ICSI) e comparar os resultados da injeção intracitoplasmática de espermatozoide entre os oócitos em telófase I (TI) e metáfase II (MII), e entre aqueles em metáfase II com e sem fuso celular visível. MÉTODOS: Estudo prospectivo que incluiu 106 pacientes inférteis submetidas à injeção intracitoplasmática de espermatozoide. Foram incluídas pacientes com idade menor ou igual a 38 anos, hormônio folículo estimulante (FSH) basal menor que 10 mIU/mL e índice de massa corpórea (IMC) menor que 30 kg/m². Foram excluídas pacientes com doenças sistêmicas, com qualquer infecção ativa, tabagistas ou que fizeram uso de medicações hormonais e anti-inflamatórias hormonais e não hormonais nos últimos dois meses, previamente à programação para o procedimento de reprodução assistida. Os oócitos com extrusão do primeiro corpúsculo polar foram avaliados pela microscopia de polarização, imediatamente antes da realização da injeção intracitoplasmática de espermatozoide, e caracterizados quanto ao estágio de maturação nuclear (telófase I ou metáfase II). Os oócitos em metáfase II foram avaliados de acordo com a presença ou não do fuso meiótico. Foram analisadas as taxas de fertilização, clivagem e o número de embriões de boa qualidade no segundo dia (D2) de desenvolvimento. Os dados foram analisados comparativamente através do teste exato de Fisher. Em todas as análises foi considerado o nível de significância de 5% (p<0,05). RESULTADOS: O fuso meiótico de 516 oócitos foi visualizado através da microscopia de polarização. Dezessete dos 516 oócitos avaliados estavam em telófase I (3,3%) e 499 (96,7%) em metáfase II. Os oócitos injetados em telófase I apresentaram taxas de fertilização significativamente menores do que os injetados em metáfase II (53 e 78%, respectivamente) e não produziram nenhum embrião de boa qualidade no segundo dia. Comparando-se os oócitos com e sem fuso celular visível, não foi observada diferença significativa nos resultados de injeção intracitoplasmática de espermatozoide. CONCLUSÕES: Oócitos injetados em telófase I apresentaram menores taxas de fertilização quando comparados aos em metáfase II. É possível que a análise do estágio de maturação nuclear oocitária, por meio da microscopia de polarização, possa ser utilizada como fator de predição das taxas de fertilização pós-injeção intracitoplasmática de espermatozoide.

O cuidado psicológico ao médico em reprodução assistida: um enquadre diferenciado

Profissionais da área da saúde entram em contato com o sofrimento humano mesmo quando não trabalham diretamente no campo da Psicologia. Este estudo baseou-se no referencial da psicanálise com vistas a compreender os aspectos do sofrimento humano que emerge para os médicos no exercício da reprodução assistida, e a importância do estudo do imaginário coletivo sobre situações de difícil manejo em suas clínicas. Participaram vinte e dois médicos que atuam em hospitais e clínicas do estado de São Paulo em âmbitos público e privado, independentemente de sexo, idade e tempo de formação. Foi utilizado o procedimento desenhos-estórias com tema, compreendido como procedimento dialógico. A entrevista caracterizou-se como uma situação especial de comunicação e expressão das emoções geradas nos atendimentos relacionados à temática proposta. Constatou-se a necessidade de proposição de espaços facilitadores da expressão emocional, que promovem a continência do sofrimento humano e a ocorrência de experiências reflexivo-vivenciais transformadoras do real.

Interação genótipo x local x regime alimentar em bovinos nelore por meio de componentes principais de três modos

O principal objetivo deste estudo foi aplicar componentes principais com múltiplas matrizes de dados para verificar a interação tripla genótipo x local x regime alimentar no valor genético do efeito direto do peso, aos 205 dias de idade. Foram utilizados touros com filhos em três regiões de produção do Nordeste Brasileiro (Maranhão, Mata e Agreste, e Recôncavo Baiano) e criados nos regimes alimentares a pasto ou com suplementação. Não se evidenciou interação genótipo x local para a característica estudada, entretanto, constatou-se interação do genótipo x regime alimentar. A utilização dos touros deve ser direcionada de acordo com o regime alimentar de seus filhos.

Dynamics of follicular growth and progesterone concentrations in cyclic and anestrous suckling Nelore cows (Bos indicus) treated with progesterone, equine chorionic gonadotropin, or temporary calf removal

The objective of this study was to investigate the effects of eCG and temporary calf removal (TCR) associated with progesterone (P4) treatment on the dynamics of follicular growth, CL size, and P4 concentrations in cyclic (n ¼ 36) and anestrous (n ¼ 30) Nelore cows. Cyclic (C) and anestrous (A) cows were divided into three groups. The control group received 2 mg of estradiol benzoate via intramuscular (IM) injection and an intravaginal device containing 1.9 g of P4 on Day 0. On Day 8, the device was removed, and the animals received 12.5 mg of dinoprost tromethamine IM. After 24 hours, the animals received 1 mg of estradiol benzoate IM. In the eCG group, cows received the same treatment described for the control group but also received 400 UI of eCG at the time of device removal. In the TCR group, calves were separated from the cows for 56 hours after device removal. Ultrasound exams were performed every 24 hours after device removal until the time of ovulation and 12 days after ovulation to measure the size of the CL. On the same day as the CL measurement, blood was collected to determine the plasma P4 level. Statistical analyses were performed with a significance level of P ≤ 0.05. In cyclic cows, the presence of the CL at the beginning of protocol resulted in a smaller follicle diameter at the time of device removal (7.4 ± 0.3 mm in cows with CL vs. 8.9 ± 0.4 mm in cows without CL; P ¼ 0.03). All cows ovulated within 72 hours after device removal. Anestrous cows treated with eCG or TCR showed follicle diameter at fixed-timed artificial insemination (A-eCG 10.2 ± 0.3 and A-TCR 10.3 ± 0.5 mm) and follicular growth rate (A-eCG 1.5 ± 0.2 and A-TCR 1.3 ± 0.1 mm/day) similar to cyclic cows (C-eCG 11.0 ± 0.6 and C-TCR 12.0 ± 0.5 mm) and (C-eCG 1.4 ± 0.2 and C-TCR 1.6 ± 0.2 mm/day, respectively; P ≤ 0.05). Despite the similarities in CL size, the average P4 concentration was higher in the A-TCR (9.6 ± 1.4 ng/mL) than in the A-control (4.0 ± 1.0 ng/mL) and C-TCR (4.4 ± 1.0 ng/mL) groups (P < 0.05). From these results, we conclude that eCG treatment and TCR improved the fertility of anestrous cows by providing follicular growth rates and size of dominant follicles similar to cyclic cows. Additionally, TCR increases the plasma concentrations of P4 in anestrous cows

Utilização de quitosana na alimentação de ruminantes

O objetivo desta revisão foi avaliar os possíveis efeitos da utilização da quitosana na nutrição de ruminantes e demonstrar os resultados obtidos com sua aplicação na dieta de bovinos no Brasil. Foram utilizados neste estudo 8 novilhos canulados da raça Nelore. Os animais foram submetidos à 4 diferentes tratamentos, sendo além do controle, fomecidas as doses de 50 mg, 100 mg ou 150 mg/kg de peso vivo (PV) de quitosana diariamente e inseri da no rúmen. Na adição da concentração de 150 mg/kg de PV de quitosana observou-se diminuição sobre o consumo de fibra detergente neutro (FDN), expressos em kg/dia e em porcentagem de PV do animal. A inclusão de quitosana na dieta proporcionou aumento da digestibilidade da matéria seca (MS), matéria orgânica (MO), proteína bruta (PB),carboidratos totais (CT), FDN e nutrientes digestíveis totais (NDT). Houve efeito quadrático sobre o N-NH3 com a inclusão de quitosana na dieta. A inclusão de quitosana na dieta alterou as proporções molares de AGCC individualmente. O aditivo proporcionou aumento das concentrações de propionato (mmol/L) a medida que se elevou as concentrações de quitosana e de forma semelhante houve aumento de 7,47% para as porcentagens molares de propionato. Houve diminuição da relação acetato:propionato, principalmente com a inclusão de 150mg/Kg de peso vivo de quitosana diariamente.Foi observado também neste trabalho, efeito linear decrescente para a proporção molar de butirato.Assim como esperado as concentrações de glicose plasmática foram influenciadas notadamente neste estudo, resultando num incremento de 18,58%, 26,35%, 23,68% respectivamente para o controle versus as três concentrações utilizadas. Estes dados são coesivos com o aumento também linear obtido na participação do propionato no total de AGCC. Embora estejam dentro dos...