Freezability genetics in rabbit semen

[EN] The aim of this study was to estimate the heritability of semen freezability and to estimate the genetic correlation between frozen-thawed sperm traits and the growth rate in a paternal rabbit line. Estimated heritabilities showed that frozen-thawed semen traits are heritable (ranged between 0.08 and 0.15). In the case of Live-FT (percentage of viable sperm after freezing), the estimated heritability is the highest one, and suggests the possibility of effective selection. After the study of genetic correlations it seems that daily weight gain (DG) was negatively correlated with sperm freezability, but no further conclusions could be drawn due to the high HPD95%. More data should be included in order to obtain better accuracy for the estimates of these genetic correlations. If the results obtained at present study were confirmed, it would imply that selection for DG could alter sperm cell membranes or seminal plasma composition, both components related to sperm cryoresistance. (C) 2017 Elsevier Inc. All rights reserved.This work was supported by the Generalitat Valenciana research program (Prometeo II 2014/036). Lavara R. acknowledges the partial support received from Generalitat Valenciana under VALid program (APOST/2014/034) and from Ministry of Economy and Competitiveness under subprogramme "Formation posdoctoral" (FPDI-2013-16707).Lavara García, R.; Moce Cervera, ET.; Baselga Izquierdo, M.; Vicente Antón, JS. (2017). Freezability genetics in rabbit semen. Theriogenology. 102:54-58. https://doi.org/10.1016/j.theriogenology.2017.07.013S545810

Breeding programmes to improve male reproductive performance and efficiency of insemination dose production in paternal lines: feasibility and limitations

[EN] This paper aims at reviewing the current genetic knowledge of the issues related to the efficient use of bucks in artificial insemination (AI). Differences between lines have been found relevant in semen production and quality traits not necessarily related to their specialization as maternal or paternal lines. Accurate heritability estimates indicate that genetic selection for increasing semen production by improving male libido and reducing the number of rejected ejaculates may not be effective. However, total sperm produced per ejaculate appears to be as an interesting trait to select for, despite that genetic correlation between ejaculate volume and sperm concentration has not been yet accurately estimated. Semen pH has shown low to medium heritability estimates and a low coefficient of variation, therefore it is not advisable to attempt improvement by direct selection. In general, sperm motility traits have shown low heritabilities but, the rate of motile sperms per ejaculate has been considered as convenient to select for. Morphological characteristics of the spermatozoa have revealed as medium to highly heritable. There are evidences of high genetic correlations between sperm traits before and after freezing-thawing. There are few studies regarding the estimation of heterosis of seminal traits but results indicate important and favorable direct and maternal heterosis in crosses between maternal lines. However, this has not been confirmed in a cross between two paternal lines. Until now, attempts to find parametric or non-parametric functions to predict ejaculate fertility through seminal characteristics recorded in routinely evaluations have been very unsatisfactory. Hence, it may be necessary to find other semen quality markers, or to evaluate some of the currently used ones in a more precise manner or closer to the AI time in order to improve the ability to predict ejaculate fertility. Several seminal characteristics phenotypically correlated to male fertility, could be considered as potential traits to select for in order to genetically improving this trait. However, only the semen pH has been checked for this purpose, and a negative result has been obtained. Other traits can be studied in the future but bearing in mind that the required experiments will need large number of bucks for an accurate estimation of the genetic correlation of the trait with male fertility. This means that these experiments will be expensive and difficult to set up. The most common criterion to select paternal lines, average daily gain, seems not to be genetically correlated to male fertility and seminal traits. Thus, selection for average daily gain has no detrimental consequences on these traits, and a multi-trait selection, including growth rate and seminal traits directly related to an efficient AI semen dose production, is feasible in paternal lines. The male contribution to fertility after natural mating and after AI with semen doses with high concentration is negligible, but it has been found that, under more restrictive conditions of AI, male contributions to fertility and litter size are low but higher in magnitude than the ones obtained after natural mating. The genetic correlation between the female and male contributions to fertility has been found to be moderate to high and positive.This study was supported by the Generalitat Valenciana Research Programme (Prometeo 2009/125) and Spanish Research Projects (INIA RTA2005-00088-CO2; INIA RTA2008-00070-CO2; CICYT AGL2008-03274). Raquel Lavara was supported by a research grant from the Spanish Ministry of Education (MEC, FPU AP2007-03755) and Llibertat Tusell by a research grant from INIA.Piles, M.; Tusell, L.; Lavara García, R.; Baselga Izquierdo, M. (2013). Breeding programmes to improve male reproductive performance and efficiency of insemination dose production in paternal lines: feasibility and limitations. World Rabbit Science. 21(2):61-75. doi:10.4995/wrs.2013.1240SWORD617521

Quantification and identification of sperm subpopulations using computer-aided sperm analysis and species-specific cut-off values for swimming speed

Motility is an essential characteristic of all fl agellated spermatozoa and assessment of this parameter is one criterion for most semen or sperm evaluations. Computer-aided sperm analysis (CASA) can be used to measure sperm motility more objectively and accurately than manual methods, provided that analysis techniques are standardized. Previous studies have shown that evaluation of sperm subpopulations is more important than analyzing the total motile sperm population alone. We developed a quantitative method to determine cut-off values for swimming speed to identify three sperm subpopulations. We used the Sperm Class Analyzer ® (SCA) CASA system to assess the total percentage of motile spermatozoa in a sperm preparation as well as the percentages of rapid, medium and slow swimming spermatozoa for six mammalian species. Curvilinear velocity (VCL) cut-off values were adjusted manually for each species to include 80% rapid, 15% medium and 5% slow swimming spermatozoa. Our results indicate that the same VCL intervals cannot be used for all species to classify spermatozoa according to swimming speed. After VCL intervals were adjusted for each species, three unique sperm subpopulations could be identifi ed. The effects of medical treatments on sperm motility become apparent in changes in the distribution of spermatozoa among the three swimming speed classes.Web of Scienc

Semen molecular and cellular features: these parameters can reliably predict subsequent ART outcome in a goat model

Currently, the assessment of sperm function in a raw or processed semen sample is not able to reliably predict sperm ability to withstand freezing and thawing procedures and in vivo fertility and/or assisted reproductive biotechnologies (ART) outcome. The aim of the present study was to investigate which parameters among a battery of analyses could predict subsequent spermatozoa in vitro fertilization ability and hence blastocyst output in a goat model. Ejaculates were obtained by artificial vagina from 3 adult goats (Capra hircus) aged 2 years (A, B and C). In order to assess the predictive value of viability, computer assisted sperm analyzer (CASA) motility parameters and ATP intracellular concentration before and after thawing and of DNA integrity after thawing on subsequent embryo output after an in vitro fertility test, a logistic regression analysis was used. Individual differences in semen parameters were evident for semen viability after thawing and DNA integrity. Results of IVF test showed that spermatozoa collected from A and B lead to higher cleavage rates (0 < 0.01) and blastocysts output (p < 0.05) compared with C. Logistic regression analysis model explained a deviance of 72% (p < 0.0001), directly related with the mean percentage of rapid spermatozoa in fresh semen (p < 0.01), semen viability after thawing (p < 0.01), and with two of the three comet parameters considered, i.e tail DNA percentage and comet length (p < 0.0001). DNA integrity alone had a high predictive value on IVF outcome with frozen/thawed semen (deviance explained: 57%). The model proposed here represents one of the many possible ways to explain differences found in embryo output following IVF with different semen donors and may represent a useful tool to select the most suitable donors for semen cryopreservation

The influence of external factors on bacteriophages—review

The ability of bacteriophages to survive under unfavorable conditions is highly diversified. We summarize the influence of different external physical and chemical factors, such as temperature, acidity, and ions, on phage persistence. The relationships between a phage’s morphology and its survival abilities suggested by some authors are also discussed. A better understanding of the complex problem of phage sensitivity to external factors may be useful not only for those interested in pharmaceutical and agricultural applications of bacteriophages, but also for others working with phages

OOCYTE GLUTATHIONE CONCENTRATION IN A RABBIT LINE SELECTED FOR OVULATION RATE

ABSTRACT The present study was designed to determine glutathione concentration in rabbit oocytes and to establish its relation to ovulation rate. Glutathione concentration is used to assess oocyte quality. A total of 59 does belonging to a line selected for ovulation rate during seven generations were mated with vasectomized males to induce ovulation. Females were slaughtered fifteen hours later and oocytes were collected by flushing the oviducts. Oocytes were processed and glutathione concentration was determined by the enzymatic recycling assay of the 5,5-dithio-bis (2-nitrobenzoic acid)-glutathione disulfide reductase. Glutathione concentration ranged from 4.7 to 10.3 pmol/oocyte. Ovulation rate was classified into three levels: low (10-14 corpora haemorragica), medium (15-16 corpora haemorragica) and high (17-24 corpora haemorragica). Oocyte glutathione concentration was significantly lower in oocytes from females with high (6.6±0.3 pmol/oocyte) and medium (7.3±0.4 pmol/oocyte) ovulation rates than in oocytes from females with low ovulation rates (8.4±0.3 pmol/oocyte). It seems that high ovulation rates could be associated with poorer oocyte quality in comparison with low ovulation rates

EFFECT OF DONOR STRAIN AND MATURATION STAGE OF RABBIT OOCYTES ON RESULTS OF PENETRATION TEST OF RABBIT SEMEN

[EN] The objective of this work was to develop a homologous in vitre penetration test to evaluate !he behaviour of rabbit sperm. Three treatments were applied to sperm (fresh, treated with heparin and frozen with a DMSO-sucrose extender), and two types of oocytes (immature or in vitre matured) belonging to tour different rabbit lines were used. The test was performed in TCM-199, under the following conditions: 37°C, 5% C02 and saturated humidi!y for 6 hours. After incubation, oocytes were denuded and they were observad under rnicroscope to record the nurnber of sperrnatozoa/oocyte. Results obtained showed significan! differences between ali !he treatments of sperm in the percentage of oocytes with adhered sperrnatozoa (80%, 57%, 28% oocytes with adhered spermatozoa for fresh, treated with heparin and frozen semen, respectively, P<0.05). At !he same time, larger number of sperm/penetrated oocyte were observad for fresh semen !han for !he other treatments (21.3± 3. 7, 3.9 ± 0.6 and 2.3 ± 0.2 sperm/oocyte for fresh, treated with heparin and frozen semen, respectively, P<0.01 ). The resistance of fresh semen to !he incubation conditions was higher !han that of frozen or treated with heparin semen, which could determine the differences observed between thern in the results of !he test. From the results obtained, it could be concluded that immature oocytes could be used to evaluate !he behaviour of rabbit sperm, since even fresh semen were capable to ad he re to !he surface of these oocytes; on !he other hand, further studies are necessary to improve the resistance a! the incubation conditions of frozen semen, which will probably perrnit to predict its fertility in vivo.[FR] L'objectif de ce travail était de développer un test in vitro homologue de pénétration des oocytes, pour évaluer le comportement des spermatoza·ides de lapins. Trois traitements ont été appliqués sur la semence (fraiche, traitée avec de l'héparine, ou congelée avec un dilueur contenant du DMSO et du sucrose) et 2 types d'oocytes (immatures ou maturés in vitro) appartenaient a 4 lignées différentes. Le test a été réalisé dans du TCM-199 dans les · conditions suivantes : 37°C, 5% de C02, atmosphére saturée en humidité pendan! 6 heures). Aprés incubation, les oocytes ont été dénudés et observés sous un microscope pour enregistrer le nombre de spermatozordes par oocyte. Les résultats obtenus mettent en évidence des différences significatives entre tous les traitements de la semence sur le pourcentage d'oocytes présentant des spermatozordes accolés (80%, 57% et 28 %, respectivement pour la semence fraiche, traitée avec l'héparine ou congelée, p<0.05). En méme temps, un plus grand nombre de spermatozo·ides/ oocyte pénétré est observé pour la semence fraiche comparé aux autres traitements (21.3± 3. 7 vs 3.9 ± 0.6 et 2.3 ± 0.2 spermatozo"ides/oocytes respectivement pour la semen ce fraTche, traitée avec l'héparine ou congelé p<0.01 ). Une meilleure résistance de la semence fraiche aux conditions d'incubation pourrait expliquer les différences obtenues. On peut conclure que les oocytes immatures peuvent étre utilisés pour évaluer le comportement des spermatozordes de lapins, puisque méme les spermatozo"ides éjaculés sont capables d'adhérer a la surface des oocytes. Cependant, de nouvelles études seront nécessaires pour améliorer la résistance des spermatozo'ides aux conditions d'incubation de la semence préalablement congelée, afin de prédire la fertilité in vivo.This work was supported by CICYT project nº AGF98-0470-C02-01. The authors thank Mr. Neil Macowan for revising the English version.Mocé, E.; Vicente, J.; Lavara, R. (2002). EFFECT OF DONOR STRAIN AND MATURATION STAGE OF RABBIT OOCYTES ON RESULTS OF PENETRATION TEST OF RABBIT SEMEN. World Rabbit Science. doi:10.4995/wrs.2002.476SWORD10

EFFECT OF SYNTHETIC PROSTAGLANDIN F2ct ANALOGUE (CLOPROSTENOL) ON LITTER SIZE AND WEIGHT IN A RABBIT LINE SELECTED BY GROWTH RATE

[EN] The effect of a treatment with a synthetic analogue of prostaglandin F2a (cloprostenol) administrated intramuscularly on day 28 of pregnancy in does belonging to a synthetic rabbit line selected by growth rate (line R) was studied. A reduction in gestation length was observed after treatrnent with prostaglandins (31.3±0.1 vs 32.4±0.1 days, for treated and control groups, respectively, P<0.05). Litter size at birth, and live-born pups were not affected by the treatment. Individual weight of young rabbits at birth was significantly different between treatrnent groups (52±1 vs 58±1 g, in treatment and control group respectively, P<0.05). In the control group, young rabbits born from multiparous does were heavier than those from pnm1parous (53±2 vs 63±1 g, in primiparous and multiparous does respectively, P<0.05). There were not differences in birth weight of kits from treated multiparous and primiparous does. At weaning, individual weight was not affected by treatrnent (578±12 and 561±10 g, in control and treatment group respectively), and differences were observed in reproductive status (513±12 vs 626±9 g, in primiparous and multiparous does respectively, P<0.05). An increase in mortality was observed during lactation period after treatrnent with PGF2a (48% vs 26%, in cloprostenol and control group respectively, P<0.01).[FR] L'objet de ce travail est d'étudier l'effet de l'injection intramusculaire d'un analogue synthétique de la prostaglandine PGF2a {Cloprostenol) au 28éme jour de gestation a des lapines appartenant a une lignée synthétique sélectionnée sur la vitesse de croissance {lignée R). La durée de 9estation est réduite aprés traitement avec les prosta9landines (31.3±0.1 vs 32.4±0.1 jours, respectivement pour le lot traité et le lot témoin, P<0.05). La taille de portée a la naissance et le nombre de nés vivants ne sont pas modifiés par le traitement. Le poids individue! des jeunes lapereaux a la naissance est si9nificativement différent entre les lots (52±1 vs 58±19, respectivement pour le lot traité et le lot témoin, P<0.05). Dans le lot témoin, les jeunes lapereaux nés de lapines multipares sont plus lourds que ceux issus de primipares (53±2 vs 63±19, respectivement pour les primipares et les multipares, P<0.05). Dans le lot traité, le poids des lapereaux a la naissance ne varie pas selon qu'ils sont issus de lapines multipares ou primipares. Au sevra9e, le poids individue! des lapereaux n'est pas modifié par le traitement (578±12 et 561±109, respectivement pour le lot témoin et le lot traité) mais des différences sont observées selon la parité des lapines (513±12 vs 626±9g, respectivement pour les primipares et les multipares, P<0.05). Cependant, le traitement avec PGF2., s'accompa9ne d'une au9mentation de la mortalité pendan! la lactation (48% vs 26%, respectivement pour le lot traité au Cloprostenol et le lot témoin, P<0.01 ).This work was supported by CICYT project nº AGL2000-0595-C03-01. The authors thank Mr. Neil Macowan for revising the English versionLavara, R.; Viudes-De-Castro, M.; Vicente, J.; Mocé, E. (2002). EFFECT OF SYNTHETIC PROSTAGLANDIN F2ct ANALOGUE (CLOPROSTENOL) ON LITTER SIZE AND WEIGHT IN A RABBIT LINE SELECTED BY GROWTH RATE. World Rabbit Science. 10(1). https://doi.org/10.4995/wrs.2002.470SWORD10