Pituitary and ovarian hormones: is their plasma concentration affected by litter size in primiparous lactating rabbit does?

[EN] Genetic selection in commercial rabbit lines based on litter size has positively improved the number of kits suckling, presumably to weaning. Although it has been proven that the energetic balance of primiparous does is due to the need to satisfy pregnancy, lactation and growth requirements, litter size adjustment from 7 to 12 kits is applied as a routine in commercial rabbit farms. The suckling stimulus provokes a prolactin (PRL) secretion, which in turn can modulate the preovulatory release of luteinising hormone (LH) and, consequently, the ovulatory and productive responses of the does. This study aimed to determine if litter size of prolific primiparous rabbit does during lactation [Group HL, with high litter density (10-12 kits; n=21) and Group LL, with low litter density (7-9 kits; n=29)] influences plasma concentration of PRL. Blood samples from lactating does were taken weekly throughout lactation starting on day 4 post-partum, until day 32 post-partum, before and immediately after suckling. In addition, the does were re-inseminated after weaning (day 32 post-partum), and sampled at 0 and 60 min after induction of ovulation to determine whether litter size affected the peak of LH, progesterone (P4) concentrations and the main productive parameters of their second pregnancy. All hormones were determined by enzyme immunoassay. Statistical analysis of the results revealed that the PRL concentrations of hyperprolific rabbit does before and immediately after a suckling stimulus from 7-9 or 10-12 kits were significanltly different, as we only detected basal levels, with a rise after weaning in both groups. More studies are necessary, delaying blood sampling to later periods of time after the suckling stimulus, in order to conclude whether the peak release of this hormone is altered or not. There were also no differences in plasma LH and progesterone levels after artificial insemination, or in productive performance of these females after their second pregnancy. In conclusion, the litter size adjustment of prolific primiparous rabbits with 7 to 12 kits determines adequate pituitary, ovarian and reproductive responses at second parturition if the does are inseminated after weaning.This work was supported by the Spanish Ministry of Economy and Competitiveness [Project AGL2015-65572-C2-R1 and Project RTI2018-094404-B-C21].Fernández-Pacheco, C.; Millán, P.; Rodríguez, M.; Formoso-Rafferty, N.; Velasco, B.; Rebollar, PG. (2021). Pituitary and ovarian hormones: is their plasma concentration affected by litter size in primiparous lactating rabbit does?. World Rabbit Science. 29(3):161-168. http://hdl.handle.net/10251/173607OJS16116829

Uso del video como metodología de aula invertida en asignaturas de experimentación animal [Using the video as flipped classroom methodology in experimental animal subjects ]

El objetivo de este estudio fue i) Evaluar el aprendizaje de los alumnos comparando las metodologías docentes, presencial y online ii) Evaluar si el alumno ha visualizado y estudiado el contenido de los videos alcanzando unos resultados de aprendizaje adecuados con la metodología de aula invertida y iii) Valorar el grado de aceptación de los materiales docentes utilizados en las prácticas por los alumnos. El nivel de conocimiento alcanzado por los alumnos con las metodologías docentes utilizadas, presencial y on line, ha sido alto y similar. Sin embargo, si se observaron diferencias en la pegunta del cuestionario donde el alumno tenía que realizar medidas y hacer cálculos, siendo más alta en presencial (8,7) que online (4,3). Las calificaciones obtenidas por los alumnos fueron altas al utilizar los videos como metodología de aula invertida. Las actividades de evaluación de tipo JCloze, fué valorada positivamente por los alumnos y se puede considerar una herramienta útil para implicar y motivar al alumno en su proceso de aprendizaje. Los alumnos, a través de las encuestas realizadas, han valorado positivamente tanto las prácticas presenciales como las realizadas a través de los videos. [The target of this study was to i) evaluate students learning by comparing classroom and online teaching methodologies. ii) Evaluate if students have visualized and studied the contents of the videos, achieving adequate learning results with the flipped classroom methodology and iii) Rate the degree of acceptance of teaching materials used in the practices by students. The level of knowledge reached by students with the teaching methodologies used, both classroom and online, has been high and similar. However, there were differences in the question where the student had to perform measurements and make calculations, being higher in face-to-face (8.7) than online (4.3). The scores obtained by the students were high when using the videos as an inverted classroom methodology. Evaluation activities of the JCloze type were positively valued by the students and can be considered a useful tool to involve and motivate the student in their learning process. The students, through the surveys, have positively valued both the face-to-face and video-based practices.

Induction of ovulation in rabbits by adding Lecirelin to the seminal dose: In vitro and in vivo effects of different excipients.

This study evaluates the effect of Lecirelin (Dalmarelin®, Fatro, Italy) diluted in different excipients (benzilic alcohol, benzoic acid and paraben) added to a seminal dose on LH concentrations, progesterone concentrations and ovarian status in rabbits. The in vitro effect on spermatozoa was also tested. A total of 100 multiparous female rabbits were divided into 5 groups, which at the moment of AI, received 0.2 mL (5 μg/dose) intramuscular (im) inoculation of Lecirelin (control) or the same Lecirelin dose administered intravaginally (iv) with the seminal dose alone (Lecirelin group) or with benzilic alcohol (Lecirelin BA group), benzoic acid (Lecirelin BAc group) or parabens (Lecirelin PA group) as an excipient. After 7 days, 10 rabbits per group were euthanized to analyze their ovarian status. In the control group, a high LH peak was detected 30 min post AI, while in the iv groups a slight increase in LH occurred after 120 min. The ovulation and fertility rate was similar in control and Lecirelin groups, while the lowest fertility rate was detected in the Lecirelin BA group. In a second experiment, the semen samples collected from male rabbits were diluted in TALP (control) or mixed with the 5 μg of Lecirelin solutions used in the first experiment. The highest percentage of capacitated sperm (68.3%) was recorded in the Lecirelin PA. The lowest percentages were observed in the Lecirelin BA and BAc groups. In conclusion, the iv administration of Lecirelin represents an alternative method for simplifying rabbit insemination procedures

Female reproduction and the microbiota in mammals: Where are we?

While it is generally accepted that the mammalian vagina contains a site-specific microbiota that plays relevant roles in genital and reproductive health, the existence of an extra-vaginal microbiota in the female reproductive tract (i.e. follicular fluid, oviduct, endometrium, and placenta) is, at least, a matter of controversy. Many conclusions in this field have failed to consider the technical limitations, biases, and confounding factors inherent to next-generation sequencing (NGS) approaches. While this creates uncertainty in the field, there is no doubt this subject is set to be the focus of new research efforts because of its scientific and practical connotations in female reproductive health. The current art state, its limitations, and gaps in our knowledge about the female reproductive tract's microbiota and, particularly, about the microbes of the extra-vaginal environment are presented in this review. Also are discussed possible relationships between the gut and oral microbiota and reproductive events

Managing Sexual Receptivity and Ovulation Induction in Rabbit Does: Evidence from Recent Research

[EN] The sexual receptivity and ovulation induction of the reproductive rabbit are key points determining their success in productive life. Adequate synchronisation of the sexual receptivity methods of inseminated rabbit does unquestionably favours fertility and prolificacy outcomes. This review aims to bring together the different methods applied in synchronising primiparous rabbits and the consequences at metabolic, endocrine and ovarian levels, as well as in the embryonic, foetal and post-natal development that our research group has studied over the years. Likewise, the latest advances regarding ovulation induction in the rabbit are described, as well as the search for alternatives to the intramuscular injection of synthetic analogues of gonadotropins and seminal plasma components that could be involved in this process. Different experiments performed with a physiological basis confirm that nerve stimulation during artificial insemination or coitus is especially important in the ovulation induction reflex in rabbit females.Rebollar, PG.; Arias-Álvarez, M.; Lorenzo, PL.; García-García, RM. (2023). Managing Sexual Receptivity and Ovulation Induction in Rabbit Does: Evidence from Recent Research. World Rabbit Science. 31(2):77-92. https://doi.org/10.4995/wrs.2023.18762779231

Supplementation with Fish Oil Improves Meat Fatty Acid Profile although Impairs Growth Performance of Early Weaned Rabbits

Our objective was to analyze the influence of replacing lard (control) with fish oil (FO) rich in long-chain n-3 polyunsaturated fatty acids in the diet of rabbits weaned at 25 days of age on their growth performance, meat quality, cecal fermentation, and ileal morphology. Twenty-four litters (12 control and 12 FO) of nine kits each were fed the experimental diets from weaning (25 days) until slaughter at 60 days of age. Half of the litters (six per diet) were used to monitor productive performance, carcass characteristics, and ileal morphology, and cecal fermentation was assessed in the rest of litters. Diet had no influence on feed intake, meat color, and pH or cecal fermentation, but FO-fed rabbits had lower (p ≤ 0.049) average daily gain, chilled carcass weight, and perirenal fat than control rabbits. Fish oil inclusion in the diet resulted in lower morbidity (5.56% vs. 20.4%; p = 0.019) and a healthier fatty acid profile with lower (p < 0.001) n-6/n-3 ratios in both muscle and perirenal fat. In summary, the inclusion of FO in the diet of early weaned rabbits improved the fatty acid profile of rabbit meat and fat and decreased the morbidity, but growth performance was slightly reduced

Gestation Food Restriction and Refeeding CompensateMaternal Energy Status and Alleviate Metabolic Consequencesin Juvenile Offspring in a Rabbit Model

Nutritional status during gestation can influence mother and offspring metabolism. Undernutrition in pregnancy affects women in both western and developing countries, and it is associated with a high prevalence of chronic diseases in later life. The present work was conducted in the rabbit model, as a longitudinal study, to examine the effect of food restriction during early and mid-gestation, and re-feeding ad libitum until the end of pregnancy on metabolic status and body reserves of mother and, its association with development and metabolism of fetuses and female offspring to the juvenile stage. Little changes in live body weight (LBW), compensatory feed intake, similar body reserves, and metabolism were observed in dams. Placenta biometry and efficiency were slightly affected, but fetal BW and phenotype were not modified. However, hyperinsulinemia, insulin resistance, and hypertriglyceridemia were demonstrated in pre-term fetuses. In the juvenile period, these changes were not evidenced, and a similar pattern of growth and serum metabolic parameters in offspring of food-restricted mothers were found, except in serum aminotransferases levels, which increased. These were associated with higher liver fibrosis. Maternal food restriction in the early and mid-pregnancy followed by re-feeding in our rabbit model established a compensatory energy status in dams and alleviated potential long-term consequences in growth and metabolism in the offspring, even if fetal metabolism was altered.This research was funded by the SPANISH MINISTRY OF SCIENCE (Grant Number: AGL2015-65572-C2-1-R and -2-R, RTI-2018-094404-B-C21 and C22) and UCM funding for RESEARCH GROUPS (Group 920249).Peer reviewe

Correction: Recombinant rabbit beta nerve growth factor production and its biological effects on sperm and ovulation in rabbits.

[This corrects the article DOI: 10.1371/journal.pone.0219780.]