Methods for evaluating the efficiency of the genetic multiplication by bovine embryo production

O objetivo deste trabalho foi avaliar estratégias de incremento da eficiência da produção in vitro de embriões bovinos (PIVE). Dois artigos foram desenvolvidos, o primeiro objetivou avaliar se o volume ovariano, a presença e o diâmetro do corpo lúteo (CL) têm efeito sobre o número e a qualidade de oócitos bovinos recuperados. O segundo artigo teve como objetivo comparar diferentes métodos estatísticos para predizer a probabilidade de gestação em um programa comercial de PIVE. Artigo 1: Foram obtidos em abatedouro 110 ovários. Os complexos cumulus-oócitos foram aspirados e avaliados em microscópio estereoscópico. Os oócitos foram contados e classificados de acordo com sua qualidade (grau I, II, III e IV). O volume do ovário foi correlacionado com o número de oócitos de boa qualidade (r = 0.33; P < 0.05). Os ovários com CL mostraram maior número de oócitos de boa qualidade do que ovários sem CL (P < 0.05). Além disso, a presença do CL e o seu diâmetro influenciaram positivamente a probabilidade de recuperação de oócitos de boa qualidade (P < 0.05). Em conclusão, o volume ovariano não é um bom parâmetro para predizer características ovarianas importantes; além disso, a análise do CL, a sua presença e seu diâmetro, pode ser uma boa ferramenta para melhorar a eficiência em programas de PIVE. Artigo 2: Redes neurais artificiais (RNA) e árvores de decisão têm provado ser bem sucedidas em diferentes áreas de estudo, tais como medicina, genética e produção animal. No entanto, a utilização destas metodologias na área de reprodução bovina ainda é muito escassa. No presente estudo, um conjunto de dados reais foi usado, composto por 9.697 transferências de embriões produzidos in vitro, 6.788 observações foram utilizadas no modelo de treinamento e 2.909 foram utilizadas para validação. O conjunto de dados foi analisado por meio de regressão logística, rede neural feed-forward, multilayer percepetron com uma e com duas camadas ocultas, e uma árvore de decisão baseada no algoritmo ID3. Todas as cinco análises foram comparadas pela curva ROC, capacidade preditiva, teste de Kolmogorov-Smirnov e correlação ponto bisserial. Em conclusão, todas as análises foram muito semelhantes. No entanto, a análise pela rede neural feed-forward classificou corretamente mais de 70% das gestações positivas. Apesar de ter classificado incorretamente quase 60% das não gestações, este resultado se torna interessante porque não detectar uma gestação positiva é mais prejudicial a um programa comercial que não detectar uma gestação negativa. Ainda assim, são necessários estudos com conjuntos de dados maiores, incluindo não somente variáveis categóricas, mas também variáveis quantitativas para garantir resultados mais precisos.The objective of the present study was to evaluate some strategies for increasing the efficiency of bovine in vitro embryo production (IVP). Two articles were developed, first one aimed to evaluate whether ovarian volume, presence and diameter of the CL have effect on the number and quality of bovine recovered oocytes. The second article aimed to compare different statistical methods to predict pregnancy in a commercial program of IVP. Article 1: one hundred and ten ovaries were obtained from slaughterhouse. Cumulus oocytes complex were aspirated and evaluated under stereomicroscope. Oocytes were counted and classified according to their quality (Grade I, II, III and IV). Ovarian volume was weakly correlated to the number of good quality oocytes (P < 0.05). Ovaries with CL show greater number of good quality oocytes than ovaries without CL (P < 0.05). Besides, presence of CL and its diameter positively influenced the probability of recovering good quality oocytes (P < 0.05). In conclusion, ovarian volume is not a good parameter itself to predict important ovarian characteristics; moreover, analysis of CL, its presence and diameter, may be a good tool to improve efficiency on IVP programs. Article 2: Artificial neural networks (ANN) and decision trees have proved to be very successful in different fields of study such as medicine, genetics and animal production. However, the use of these methodologies in bovine reproduction is still very scarce. In this study, a real dataset was used, consisting of 9,697 embryo transfers, 6,788 observations were used in training model and 2,909 were used for validation. Dataset was analyzed by logistic regression, feed-forward neural network, multilayer perceptron with one and two hidden layers, and a based on ID3 algorithm decision tree. All analyses were compared by ROC curve, predictive capacity, Kolmogorov-Smirnov test, and point biserial correlation. In conclusion, all analyzes were very similar. Nevertheless, analysis by the feed-forward neural network correctly classified more than 70 % of positive pregnancies. Despite having incorrectly classified almost 60 % of non-pregnancies, this result becomes interesting because not detect a positive pregnancy is more harmful to a commercial program than not detect a negative pregnancy. Still, studies with larger dataset and more explanatory variables are required, including not only categorical variables, but also quantitative variables to ensure more accurate results.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Vitamin E on cryopreservation of goat semen.

O objetivo deste estudo foi verificar se a vitamina E afeta a integridade estrutural da membrana plasmática dos espermatozóides caprinos, bem como verificar o potencial uso desta vitamina em meios diluentes de criopreservação de sêmen caprino. Foram utilizados 2 machos adultos da raça Parda alpina. Para as coletas de sêmen foi utilizada vagina artificial onde se obteve 8 ejaculados por animal. Após a coleta, fez-se a avaliação física do sêmen, morfológica dos espermatozóides e da integridade funcional da membrana espermática pelo teste hiposmótico. Em seguida, o sêmen foi diluído com os seguintes tratamentos: BIOXCELL® (Controle), BIOXCELL® + Equex, BIOXCELL® + Vitamina E 25&#956;M, BIOXCELL® + Vitamina E 50&#956;M e BIOXCELL® + Vitamina E 100&#956;M. Após as diluições finais, foram avaliados a motilidade progressiva e vigor espermático e realizado teste hiposmótico de cada tratamento. O sêmen foi envasado em palhetas de 0,25mL, as palhetas foram resfriadas a 5 oC, durante 1 hora em refil plástico contendo álcool etílico. O pré-congelamento foi realizado em vapor de nitrogênio líquido durante 15 minutos. Após esse período, as palhetas foram imersas no nitrogênio para o congelamento final do sêmen. As partidas foram descongeladas em banho-maria a 37 oC por 30 segundos, acondicionadas em tubos plásticos e homogeneizadas para a análise imediata de motilidade e vigor espermático, teste hiposmótico e teste de termorresistência. No sêmen fresco, as características físicas e morfológicas mantiveram-se dentro de parâmetros normais. Não houve correlação da motilidade progressiva com outras variáveis. O volume apresentou correlação negativa com o vigor espermático, defeitos menores e defeitos totais (r = -0,55, r = -0,52 e r = - 0,53, respectivamente) e correlação positiva com o teste hiposmótico (r = 0,44). Houve correlação média negativa (r = -0,48) entre a concentração de espermatozóides e os defeitos maiores. Os valores de defeitos menores e defeitos totais apresentaram correlação forte e positiva (r = 0,98). A motilidade progressiva, o vigor espermático e o teste hiposmótico do sêmen diluído não diferiram entre os tratamentos (P > 0,05). As médias gerais de motilidade e vigor logo após o descongelamento e ao longo do TTR não diferiram (P > 0,05) entre os tratamentos. A integridade funcional da membrana espermática, avaliada pelo teste hiposmótico, não diferiu (P > 0,05) entre os tratamentos. Foi observada correlação positiva entre motilidade e vigor dos espermatozóides em todos os tratamentos no sêmen diluído (pré-resfriado) e em todos os tempos do TTR. Não houve correlação entre o vigor e o teste hiposmótico dos espermatozóides em nenhum dos tratamentos no sêmen diluído e nos tempos 0H e 2H do TTR, havendo correlação média positiva no tratamento Equex no tempo 1H (r = 0,51) e nos tratamentos Controle, Equex e Vit. E 50&#956;M no tempo 3H (r = 0,44, 0,69, 0,57, respectivamente). Houve correlação entre a motilidade e o teste hiposmótico do sêmen diluído no Tramento Vit. E 50&#956;M (r = 0,68). As amostras de sêmen dos tratamentos Equex e Vit. E 100&#956;M descongeladas mostraram correlações entre motilidade e teste hiposmótico. Conclui-se que: Nenhum dos parâmetros avaliados neste estudo foi afetado pela Vitamina E.The objectives of this study were to examine whether vitamin E has an effect on the structural integrity of goat sperm plasma membrane, as well to investigate the potential use of this vitamin in extenders medium for cryopreservation of goat semen. Two adult Parda Alpina breed males were used, totalizing 8 semen samples for each one. After collection, the physical characteristics of the semen, the sperm morphology and the functional integrity of sperm membrane by hypoosmotic swelling test were evaluated. Then the semen was diluted as follows: BIOXCELL® (Control), BIOXCELL® + Equex, BIOXCELL® + Vitamin E (25&#956;M), BIOXCELL® + Vitamin E (50&#956;M) and BIOXCELL® + Vitamin E (100&#956;M). After the final dilutions, the progressive motility, sperm vigor and hypoosmotic swelling test were performed for each treatment. The semen was packaged in 0.25 ml straws, the straws were cooled to 5 oC for 1 hour in plastic container containing ethyl alcohol. The pre-freezing was done in liquid nitrogen vapor for 15 minutes. After this period, the straws were immersed in liquid nitrogen. The samples were thawed in a water bath at 37 oC for 30 seconds, packaged in plastic tubes and homogenized for immediate analysis of sperm motility and vigor, hypoosmotic swelling test and thermoresistance test. In fresh semen, the physical and morphological characteristics remained within normal parameters. No correlation of motility with other variables were detected. The average volume correlated negatively with sperm vigor, minor defects and total defects (r = -0.55, r = -0.52 and r = -0.53, respectively) and positive correlation with the hypoosmotic swelling test (r = 0, 44). A negative correlation (r = -0.48) was found between sperm concentration and major defects. The minor defects and total defects values were markedly positive correlated (r = 0.98). The treatments did not differ (P > 0.05) for progressive motility, spermatic vigor and hypoosmotic swelling test of semen. The motility and vigor after thawing and during the TTR did not differ (P > 0.05) among treatments. No significant difference (P > 0.05) among treatments after the completion of the hypoosmotic swelling test was detected. Correlation was observed between motility and vigor in all treatments in the diluted semen (pre-cooled) and at all times of the TTR. No correlation between the vigor and the hypoosmotic swelling test in any of the treatments on 0H and 2H of TTR times was found, however a correlation at 1H time Equex treatment (r = 0.51) and the Control, Equex and Vit. E 50&#956;M treatment at time 3H (r = 0.44, 0.69, 0.57, respectively) were found. The thawed semen samples from Equex treatment and Vit. E 100&#956;M treatment showed correlation between motility and hypoosmotic swelling test. It is concluded that: The vitamin E did not affect any of parameters under study.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Análise de associação genômica ampla associa o gene Lin-28 à idade ao primeiro parto na raça Nelore

peer reviewe

Recombinant bovine somatotropin in the synchronization of ovulation in crossbred dairy cows (Bos taurus indicus × Bos taurus taurus)

Aim: The aim of this study was to evaluate the effects of the administration of recombinant bovine somatotropin (rbST) at the moment of implementation of the timed artificial insemination protocol, on follicular dynamics and pregnancy rate in crossbred cows. Materials and Methods: A total of 346 cows were used in two experiments with a factorial 2×2 design. The cycling cows (Tcycling) and the anestrous cows (Tanestrous) were considered as factor 1 and the administration of rbST (TrbST) or not (Tcontrol) as factor 2. The experimental protocol: (1) Tcontrol – day 0 (D0), insertion of a progesterone-release intravaginal device (PRID) plus 2 mg of estradiol benzoate (EB); D8, PRID removal, plus 0.150 mg of prostaglandin F2α, and 400 IU of equine chorionic gonadotropin; D9, 1 mg of EB; and with artificial insemination at day 10; (2) TrbST – similar to Tcontrol plus 500 mg of rbST on D0. In experiment I, ultrasound examinations were performed in all treatments. In experiment II, the cows' pregnancy rate was evaluated. Data were analyzed with 5% probability. Results: There was no effect of the protocols on cows cyclicity or follicular growth rate (p>0.05). There was no interaction of the effects, administration of rbST, and the cyclicity of cows on the pregnancy rate. The total pregnancy rate observed was 49.0%. The pregnancy rate in cows receiving rbST was lower for anestrous compared with cycling cows (p<0.05). Conclusion: The administration of rbST did not alter the patterns of follicular dynamics nor the ovulation rate. However, cows in anestrous that received rbST had lower pregnancy rates than cycling cows

CARACTERÍSTICAS DO SÊMEN CAPRINO DESCONGELADO APÓS A ADIÇÃO DE RINGER LACTATO, CITRATO DE SÓDIO E SOLUÇÃO TRIS

Cryopreservation of semen is of great importance for various reproductive biotechnologies such as artificial insemination (IA), In Vitro Embryo Production (PIV) and Intracytoplasmic Sperm Injection (ICSI). The objective of this work was to evaluate the stability and persistence of motility and strength of sperm, as well as changes in the plasma membrane after the addition of Ringer Lactate, sodium citrate 2.92% or TRIS solution in thawed goat semen. Semen was collected from two Alpine Brown goats, and standard procedures for cryopreservation and seminal analysis were performed. After thawing the semen, the extenders Ringer Lactate, sodium citrate 2.92% and TRIS solution were added and Thermoresistance (TTR), Supravital and Morphology Tests were carried out. In TTR, only the group received TRIS solution presented motility and strength for a longer period (90 minutes; P 0.05). We concluded that the addition of the solutions does not allow a large persistence of motility and strength of thawed sperm, but TRIS solution could be used for expansion of seminal doses used in vitro reproductive biotechnology

Influence of corpus luteum and ovarian volume on the number and quality of bovine oocytes

In order to evaluate whether ovarian volume, presence and diameter of the corpus luteum (CL) have effects on the number and quality of bovine recovered oocytes, 110 ovaries were obtained from the slaughterhouse. Cumulus oocytes complex were aspirated and evaluated under stereomicroscope. Oocytes were counted and classified according to their quality (Grades I, II, III and IV). Ovarian volume was weakly correlated to the number of good quality oocytes (P < 0.05). Ovaries with CL showed greater numbers of good quality oocytes than ovaries without CL (P < 0.05). Further, presence of CL and its diameter positively influenced the probability of recovering good quality oocytes (P < 0.05). In conclusion, ovarian volume is not a good parameter itself to predict important ovarian characteristics; moreover, analysis of CL, its presence and diameter, may be a good tool to improve efficiency on in vitro embryo production programs

Association of Vitamin E with Rapid Thawing on Goat Semen

The aim of this study was to evaluate the effects of vitamin E associated with rapid thawing on cryopreserved goat semen. Two bucks were used and eight ejaculates per animal were collected using artificial vagina. Semen was diluted with the following treatments: BIOXCELL (control), BIOXCELL + Equex (sodium lauryl sulphate) and BIOXCELL + vitamin E 100 μM. Semen was packaged into 0.25 mL straws and cooled at 5°C for 1 hour. Freezing was performed in liquid nitrogen vapor (−155°C) during 15 minutes. Then, the straws were immersed in liquid nitrogen (−196°C). Straws were thawed at 38°C/60 seconds or at 60°C/7 seconds with immediate sperm analysis. Hypoosmotic swelling test was performed adding a 20 μL aliquot of thawed semen to 1 mL of hypoosmotic solution (100 mOsm·Kg−1) followed by incubation during 60 minutes in water bath (38°C). Vitamin E did not affect any studied parameters (P>0.05). Nevertheless, defrosting rate of 60°C/7 seconds improved sperm membrane functional integrity (P<0.05). Current knowledge about goat semen cryopreservation is not sufficient to ensure high post-thawing recovery rates; thus, this study brings important data about using antioxidants and different thawing rates on cryopreservation process

Relationship of testicular biometry with semen variables in breeding soundness evaluation of Nellore bulls

This study aimed to evaluate the correlation between testicular biometry and semen variables, as well as, to relate testicular variables to the probability of selecting Nellore bulls with desirable sperm morphology when conducting breeding soundness evaluations (BSE). A total of 2055 BSEs from 506 bulls comprised the dataset. Biometric variables evaluated were: scrotal circumference, testicular volume, width, length, ratio and eccentricity; and semen variables were sperm motility, major sperm defects, minor sperm defects and normal sperm. Data of testicular biometry were correlated with data for semen variables using the Pearson’s correlation assessment. Effects of testicular variables in selecting for sperm morphology of bulls in the BSE were evaluated by logistic regression. Scrotal circumference, testicular volume, length and width were positively correlated to sperm motility (0.18 to 0.19) and normal sperm (0.24 to 0.27) and negatively correlated with values for major defects (−0.24 to −0.27), but for testicular ratio and eccentricity there were coefficients near zero for all semen traits. Testicular ratio and eccentricity were not suitable for predicting the probability of selecting a bull based on semen variables using the BSE, but scrotal circumference, testicular volume, length and width were highly significant (P <  0.0001) with moderate values of area under ROC (Receiver Operating Characteristics) curve (0.608 to 0.620)

Benchmarking Bayesian genome enabled-prediction models for age at first calving in Nellore cows

Cow fertility traits are key factors that influence beef production profitability, and is particularly important in tropical environments where achieving high reproductive rates is challenging. Genomic selection (GS) has the potential to improve genetic gain rates for reproduction, if genomic estimated breeding values (GEBV) for these traits are sufficiently accurate. Several Bayesian models have already been proposed for GS, but the benchmarks used to compare them are still scarce, mainly for age at first calving (AFC) in Nellore cattle. A total of 714 AFC records of Nellore cows and 70 K SNPs were used to compare five models, Bayes A (BA), Bayes B (BB), Bayes Cπ (BCπ), Bayesian LASSO (BL) and Bayesian Ridge Regression (BRR). These models were compared by cross validation, randomly partitioning the whole population into 7 subsets (7-fold) and replicated 15 times. The prediction accuracy were 0.24 (0.11), 0.23 (0.11), 0.33 (0.13), 0.24 (0.11) and 0.38 (0.13), for BA, BB, BCπ, BL and BRR, respectively. Thus, BRR resulted in 14%, 15%, 5% and 14% additional prediction accuracy compared to BA, BB, BCπ and BL, respectively. Pearson and Spearman correlations between GEBVs obtained from BRR and BB models were, 0.97 and 0.94, respectively. It suggested that little difference in terms of animal selection would result from these methods. A more parsimonious model, such as BRR, can be successfully used in breeding programs to generate GEBVs which further enable consistent selection decisions. Although moderate accuracies of GEBV for AFC can be achieved, we found low efficiency of GS for AFC in the present population due to the small sample size and low heritability, reinforcing that GS efficiency is highly dependent upon these factors

Aspects of sexual precocity and morphometry of uterus, placenta and embryos/fetuses in Piau breed and Commercial line gilts

In view of the importance of the genetic material of local breeds in the swine industry and the lack of information about reproductive performance of Piau females, two experiments were conducted to evaluate puberty and sexual maturity as well as the morphometry of embryos/fetuses, placenta and uterus during the first 90 days of gestation in Piau breed and Commercial line gilts. In experiment I, 37 Piau and 25 commercial line gilts were used. From the 120 days of age, detection of estrus was performed using mature boars from the first to third estrus of each gilt. Data regarding to age, body weight and estrus duration were recorded. After third estrus, females were slaughtered and ovaries were collected to determine ovulation rate. In experiment II, 36 Piau and 18 commercial line gilts were distributed into three groups according to the mating: Commercial, commercial line females x commercial line male; cross-mated, Piau females x commercial line male; and Piau, Piau females x Piau male. Gilts were slaughtered at 7, 15, 30, 45, 60 and 90 days of pregnancy. Piau females reached puberty and sexual maturity at the same age as commercial line females, but with lower weight; moreover, Piau group showed negative correlations of birth weight with puberty (−0.27) and sexual maturity (−0.29). Commercial gilts presented higher ovulation rate, weight and length of uterus, and length and thoracic circumference of fetuses. Nevertheless, number of fetuses was similar in all groups at 90 days of gestation suggesting that Piau females present higher survival rates of the conceptuses. The results showed differences between the genetic groups related to fetal and placental development, gestational losses, number of ovulations and uterine development. In addition, an intermediate status of fetal weight was observed in Piau/Commercial line crossbred conceptuses; thus, the selection of Piau females on reproductive traits to be mated with commercial line males would be an alternative to contribute to improvement of intramuscular fat content