The nuclear stage at which oocytes are cryopreserved influences further development ability and cryopreservation affects ultrastructure of both cumulus cells and the oocyte. In this work, we analyze the effects of vitrification at different nuclear and cytoplasmic maturation stages on the oocyte ultrastructure and developmental ability. Culture in TCM199 + PVA with roscovitine 25 M during 24 h led to meiotic arrest (MA) in cumulus-oocyte complexes (COCs), while permissive in vitro maturation (IVM) was performed in TCM199, 10% FCS, FSH-LH and 17b-estradiol for 24 h. Oocytes were vitrified using the open pulled straw method (OPS) with minor modifications. Fresh and vitrified/warmed COCs were fixed as immature, after IVM, after meiotic arrest (MA) and after MA + IVM.Vitrification combined with MA followed by IVM produced the highest rates of degeneration, regardless of the vitrification time. As a consequence, lower proportions of embryos cleaved in these groups, although differences were eliminated at the five-eight cell stage. Development rates up to day 8 were similar in all experimental groups, being significantly lower than those in fresh controls. Only oocytes vitrified after IVM were able to give blastociysts. The morphological alterations observed can be responsible for compromised development. More research is needed to explain the low survival rates of the bovine oocyte after vitrification and warming. #

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Veterinary Record (1996) 139, 93-94 THE tendency among pigs towards impaired reproductive efficiency during the summer has been reported by many authors with perhaps the first report being MacLean (1969). The main symptom of this summer infertility syndrome is a marked fall in fertility (Love 1978, 1981, Stein and others 1984, Hennessy 1987, Hancock 1988. Since no data exist concerning this syndrome in Spain, a retrospective study was performed in order to establish whether seasonal variations existed in the reproductive performance of sows kept under intensive housing conditions. The study was based on the individual registers of 932 large white cross landrace sows, all between their first and eighth parturitions, from an intensive piggery in north west Spain. On this farm artificial insemination is practised systematically using the seminal rich fraction diluted in a commercial solvent (MR-A;Kubus, SA) ensuring at least 3 x 109 sperm cells per 100 ml dose.After oestrus diagnosis by standing reflex, most of the sows were inseminated once every 12 hours for 36 hours. The first insemination was made at the time of the first positive oestrus diagnosis. Sows were checked by heat diagnosis twice daily. In this herd pregnancy tests are made hormonally, by injecting 400 iu of pregnant mare serum gonadotrophin and 200 iu of human chorionic gonadotrophin (PG-600; Intervet) on day 21 after mating, negative responders returning to oestrus between three and seven days after the injection. The sows were penned individually adjacent to the boars' stalls and tethered by the neck. The minimum and maximum average temperatures for each year in the area, given as the mean temperature for 24 hours averaged over the entire month, and the highest and lowest temperature for that month were as follows: for 1990, minimum (December) 24°C (range 13-2°C to -6.2°C) with 78 per cent relative humidity and maximum (July) 21-30C (35-80C to 5-0°C) with 51 per cent relative humidity; for 1991, minimum (January) 2-3°C (11-8°C to -6-2°C) with 78 per cent relative humidity, maximum (August) 21-8°C (34-80C to 6-2°C) with 49 per cent relative humidity; and for 1992, minimum (January) 1.7°C (14-20C to -2-40C) with 73 per cent relative humidity and maximum (July) 20-70C (34-4°C to 6.8°C) with 51 per cent relative humidity.The following parameters were studied: (1) return to oestrus rate; (2) abortion rate; (3) fertility; (4) litter size, live births and TABLE 1: Variations in litter size, live births and stillbirths (mean ± sem) of sows mated in different seasons over a three-year period Season Litter size Live births Stillbirths Winter 9.65 ± 0-16a 9.33 + 0.14a 0-53 + 0Q05C Spring 9-65 ±0-16a 9.11 +0.14a 0*63 ±0.07c Summer 8.42 ± 0.20b 8-17 + 0.17b 0.87 ±0.07d Autumn 9-48 ± 0-14a 9.15 + 0-12a 0.65 + 0Q05C a-b within a column, means with different superscripts are different (P<0.0001) c-d within a column, means with different superscripts are different (P<0.001)TABLE 2: Variations in fertility, return to oestrus rate and abortions of sows mated in the...

No abstract

In this study, we determined the occurrence of reproductive diseases in does on 1373 visited farms in Spain and Portugal, between 1994 and 2019. The retrospective information obtained was entered in a database classified as follows: apparent infertility (≤70% pregnancy rate), abortions (≥2% of serviced does), high fetal death risk at parturition (≥10%) or dystocia, amongst others. Infertility was the reason for 181 visits. The median of prevalence of apparent infertility in these cases was 35% (minimum to maximum: 25–90%) and the mean, 37.4%. We performed a prospective study to determine risk factors at the individual and farm level, with a second database corresponding to 2014–2019. We carried out pregnancy checks, assessed sanitary status and body condition, and recorded the age of 17,297 rebred lactating does on 142 farms. The median size of the farms was 800 does, and the examined cohorts, 350 does. Predisposing risk factors for infertility were observed: e.g., mastitis had an effect. During the 5-year study, we made a third database with the results from 190,508 does palpated by producers in a subset of 134 farms. In this case, the median of the prevalence of apparent infertility was 14.5% (minimum to maximum: 4.1–50%), which could be considered baseline occurrence when monitoring the theriogenology of rabbit doe farms. Reproductive rhythm was an enabling risk factor: does serviced ≤25 d postpartum were less fertile than at ≥32 d. We made a database with the body condition score (BCS) on a linear scale from 1 (emaciated) to 9 (obese). The pregnancy rate (PR) of underweight and borderline does (4/9) was 73.1%. The PR of overweight and borderline does (6/9) was 82.6% and those classified with a mean BCS (5/9): PR = 79.3%. We may infer that the optimum BCS for reproduction is 6/9, rather than 5/9. Some changes in female rabbit health and husbandry to improve reproductive performance and welfare are highlighted.