Litter size component traits in two Algerian rabbit lines

[EN] The aim of this study was to estimate the limiting litter size components in rabbit females from a Synthetic line (n=32) and a Local population (n=34). Ovulation rate, number of implanted and live embryos were counted by laparoscopy at 12 d after mating. Prolificacy (total newborn, number born alive and mortality) and embryonic, foetal and prenatal survival at day of birth of the 3rd gestation were measured. The analysed traits were body weight of the female at mating, ovulation rate, implanted, live and resorbed embryos, embryonic, foetal and prenatal survival, as well as total newborn, number born alive and mortality at birth. Synthetic line females had a higher ovulation rate compared to the Local population (11.03±0.23 vs. 8.41±0.23 corpora lutea; P<0.0001). Synthetic line displayed a higher number of implanted embryos (10.00±0.25 vs. 7.85±0.25 embryos; P<0.0001). No difference was found between groups for number of resorbed embryos. Similar embryonic, foetal and prenatal survival rates were reported between the Synthetic line and the Local population. Additionally, total newborn was higher in the Synthetic line than in the Local population (+1.46 kits; P<0.05). A principal components analysis was performed. The first four principal components (PC) explained more than 90% of the total variation in both lines. Total newborn, number born alive and live embryos were the main variables defining the 1st PC. Resorbed embryos and foetal survival were located in the 2nd PC. Ovulation rate and embryonic survival were the predominant variables defining the 3rd PC. The body weight of females was located in the 4th PC. The phenotypic correlation between total newborn and its components were high and positive in both lines, except for ovulation rate and total newborn, where it was moderate in Synthetic line. In conclusion, the females from Synthetic line have a higher total newborn than those from Local population, as a consequence of a higher number of released oocytes and embryos that successfully reach implantation. However, a higher uterine crowding in Synthetic line seems to limit survival of foetuses that reach term of gestation, while ovulation rate is the principal limiting factor of total newborn in Local population.The authors are grateful to Halfaoui Mobarek Said and Hamed Khodja Nabil for their valuable support during this experiment.Belabbas, R.; García, MDLL.; Ainbaziz, H.; Berbar, A.; Argente, MJ. (2021). Litter size component traits in two Algerian rabbit lines. World Rabbit Science. 29(1):51-58. https://doi.org/10.4995/wrs.2021.14247OJS5158291Adams C.E. 1960. Prenatal mortality in the rabbit Oryctolagus cuniculus. J. Reprod. Fertil., I: 36-44. https://doi.org/10.1530/jrf.0.00100366Argente M.J., Santacreu M.A., Climent A., Blasco A. 2003. Relationships between uterine and fetal traits in rabbit selected on uterine capacity. J. Anim. Sci., 81: 1265-1273. https://doi.org/10.2527/2003.8151265xArgente M.J., Santacreu M.A., Climent A., Blasco A. 2006. Influence of available uterine space per fetus on fetal development and prenatal survival in rabbits selected for uterine capacity. Livest. Sci., 102: 83-91. https://doi.org/10.1016/j.livprodsci.2005.11.0222Argente M.J., Santacreu M.A., Climent A., Blasco A. 2008. Effect of intra uterine crowding on available uterine space per fetus in rabbits. Livest. Sci., 114: 211-219. https://doi.org/10.1016/j.livsci.2007.05.008Badawy A.Y., Peiró R., Blasco A., Santacreu M.A. 2016. Effect of increased ovulation rate on embryo and fetal survival as a model for selection by ovulation rate in rabbits. World Rabbit Sci., 24: 87-94. https://doi.org/10.4995/wrs.2016.3992Belabbas R., García M.L., AinBaziz H., Berbar A., Zitouni G., Lafri M., Bouzouan M., Merrouche R., Ismail D., Boumahdi Z., Benali N., Argente M.J. 2016. Ovulation rate and early embryonic survival rate in female rabbits of a synthetic line and a local Algerian population. World Rabbit Sci., 24: 275-282. https://doi.org/10.4995/wrs.2016.5301Belabbas R., García M.L., AinBaziz H., Benali N., Berbar A., Boumahdi Z., Argente M.J. 2019. Growth performances, carcass traits, meat quality, and blood metabolic parameters in rabbits of local Algerian population and synthetic line. Vet. World, 12: 55-62. https://doi.org/10.14202/vetworld.2019.55-62Beier H.M., 2000. The discovery of uteroglobin and its significance for reproductive biology and endocrinology. Ann. NY. Acad. Sci., 923: 9-24. https://doi.org/10.1111/j.1749-6632.2000.tb05516.xBlasco A., Bidanel J.P., Bolet G., Haley C.S., Santacreu M.A., 1993a. 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Semen production in two rabbit lines divergently selected for 63-d body weight. Theriogenology, 66: 2165-2172. https://doi.org/10.1016/j.theriogenology.2006.07.004Calle E.W., García M.L., Blasco A., Argente M.J. 2017. Relationship between body condition and energy mobilization in rabbit does. World Rabbit Sci., 25: 37-41. https://doi.org/10.4995/wrs.2017.5674Cartuche L., Pascual M., Gomez E.A., Blasco A. 2014. Economic Weights in Rabbit Meat Production. World Rabbit Sci., 22: 165-177. https://doi.org/10.4995/wrs.2014.1747Chen Z.Y., Dziuk P.J. 1993. Influence of initial length of uterus per embryo and gestation stage on prenatal survival, development and sex ratio in the pig. J. Anim. Sci., 71: 1895-1901. https://doi.org/10.2527/1993.7171895xEzzeroug R., Belabbas R., Argente M.J., Berbar A., Diss S., Boudjella Z., Talaziza D., Boudahdir N., García M.L. 2020. Genetic correlations for reproductive and growth traits in rabbits. Can. J. Anim. 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Changes in endometrial vascularity during implantation and pregnancy in the rabbit. Am. J. Anat., 118: 249-282. https://doi.org/10.1002/aja.1001180113Hulot F., Mariana J.C., Gattiau G. 1985. Effet du génotype, de l'âge et de la saison sur les follicules préovulatoires de la lapine 8 heures après la saillie. Reprod. Nutr. Dev., 25: 17-32. https://doi.org/10.1051/rnd:19850102Koenig J.L.F., Zimmerman D.R., Eldrige F.E., Kopf J.D. 1986. The effect of superovulation and selection for high ovulation rate on chromosomal abnormalities in swine ova. J. Anim. Sci., 63: 202.Laborda P., Mocé M.L., Santacreu M.A., Blasco A. 2011. Selection for ovulation rate in rabbits: Genetic parameters, direct response, and correlated response on litter size1. J. Anim. Sci., 89: 2981-2987. https://doi.org/10.2527/jas.2011-3906Laborda P., Mocé M.L., Blasco A. and Santacreu M.A. 2012. Selection for ovulation rate in rabbits: Genetic parameters and correlated responses on survival rates. J. Anim. Sci., 90: 439-446. https://doi.org/10.2527/jas.2011-4219Land R. B., Falconer D.S. 1969. Genetic studies of ovulation rate in the mouse. Genet. Res., 13: 25-46. https://doi.org/10.1017/S0016672300002718Mocé M.L., Santacreu M.A., Climent A., Blasco A. 2004. The effect of divergent selection for uterine capacity on fetal and placental development at term in rabbits: Maternal and embryonic genetic effects. J. Anim. Sci., 82: 1046-1052. https://doi.org/10.2527/2004.8241046xMocé M.L., Santacreu M.A., Climent A., Blasco A. 2005. Divergent selection for uterine capacity in rabbits, III. Responses in uterine capacity and its components estimated with a cryopreserved control population. J. Anim. Sci., 83: 2308-2312. https://doi.org/10.2527/2005.83102308xMocé M.L., Blasco A., Santacreu M.A. 2010. In vivo development of vitrified rabbit embryos: Effects on prenatal survival and placental development. 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Direct responses to six generations of selection for ovulation rate or prenatal survival in Large White pigs. J. Anim. Sci., 85: 356-364. https://doi.org/10.2527/jas.2006-507Ruíz-Flores A., Johnson R.K. 2001. Direct and correlated responses to two-stage selection for ovulation rate and number of fully formed pigs at birth in swine. J. Anim. Sci., 79: 2286-2297. https://doi.org/10.2527/2001.7992286xSaacke R.G., Dalton J.C., Nadir S., Nebel R.L., Bame J.H. 2000. Relationship of seminal traits and insemination time to fertilization rate and embryo quality. Anim. Reprod. Sci., 60: 663-677. https://doi.org/10.1016/S0378-4320(00)00137-8Salvetti P., Guérin P., Theau-Clément M., Hurtaud J., Beckers J.F., Joly T. 2007. Essais d'amélioration de la production d'embryons chez la lapine. In Proc.: 12èmes Journées de la Recherche Cunicole, 27-28 Novembre, 2007, Le Mans, France, 41-44.Santacreu M.A., Viudes M.P., Blasco A. 1990. Evaluation par coelioscopie des corps jaunes et des embryons. Influence sur la taille de portée chez la lapine. Reprod. Nutr. Dev., 30: 583-588. https://doi.org/10.1051/rnd:19900503Santacreu M.A., Gou P., Blasco A. 1992. Relationships between ovulation rate, embryo survival and litter size in rabbits. Anim. Sci., 55: 271-276. https://doi.org/10.1017/S0003356100037557Santacreu M.A., Mocé M.L., Climent A., Blasco A. 2005. Divergent selection for uterine capacity in rabbits. II. Correlated response on litter size and its components estimated with a cryopreserved control population. J. Anim. Sci., 83: 2303-2307. https://doi.org/10.2527/2005.83102303xSAS Institute, 2019. SAS Institute Inc., SAS 9.4 Help and Documentation, Cary, NC: SAS Institute Inc., 2019.Sid S., Benyoucef M.T., Mefti-Korteby H., Boudjenah H. 2018. Performances de reproduction des lapines de souche synthétique et de population blanche en Algérie. Livest. Res. Rural. Dev., 30:7. http://www.lrrd.org/lrrd30/7/sid30120.htmlTorrès S., Hulot F., Sevellec C. 1987. 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Prenatal factors affecting the probability of survival between birth and weaning in rabbits

The aim of this study was to analyse the relationships between kit birth weight and litter size with kit survival from birth to weaning, and to estimate the effects of place of birth, nest quality, cannibalism, lactation, parity order, season and sex. A total of 1696 kits from 82 females of the ITLEV2006 synthetic line were used in this study. A logistic regression was performed. Kit birth weight was directly related to the probability of the kit’s survival from birth to weaning, and increasing birth weight by one gram increased the likelihood of kit survival by 8% to 10% (P<0.001). In line with the decrease in birth weight of kits as the number of kits at birth increases, litter size showed a negative relationship to the probability of survival from birth to weaning, and increasing the litter by one kit at birth decreased the probability of survival of the kits by 5% to 9% (P<0.05). Regarding effects, cannibalism events in the litter decreased the probability of survival of the kits in the first week of life (P<0.01). Being born in the cage decreased the probability of survival of the kits from birth to weaning, and kits born outside the nest had a lower chance of survival than those born inside the nest (P<0.01). The order of parturition had a positive effect on probability of survival of the kits from 5 days of age to weaning (P<0.05). Female kits had a lower chance of survival than male kits, but only until 5 days of age (P<0.01). The lactation status displayed a negative effect on the probability of survival of the kits in the first week of life, and kits gestated in lactating females had a lower chance of survival than those gestated in non-lactating females (P<0.05). In conclusion, the probability of kit survival in the first days after parturition was affected mainly by its weight at birth, litter size, cannibalism events, place of birth of kit, parity order, sex and lactation status, while the probability of kit survival at weaning was directly related to its weight at birth, litter size, place of birth of kit and parity order

Environmental and Genetic Factors Affecting Litter Size Components in Rabbits

[EN] In rabbits, ovulation rate is, together with prenatal survival, one of the main limiting factors for litter size. Both components are affected by several factors related to females and their environment. Thus, understanding these components and their factors of variation is key in designing diets, optimisation of reproductive performance and genetic selection. In this review, authors summarise the main components of litter size and their environmental factors of variation. Genetic factors and the main results of genetic selection programmes on components of litter size are also summarised. In this regard, a negative effect of dietary restriction and reduced day light hours is found, as well as a positive effect of body condition, parity order and age of female on ovulation rate. However, an increase in deterioration of oocyte quality has been reported as ovulation rate increases, leading to decreased embryonic and foetal survival. Dietary restriction and heat stress also have a negative effect on embryonic and foetal survival, increasing the failures during gestation while good vascularisation and enough available space in uterine horn are keys to embryonic and foetal survival. Ovulation rate was proposed as indirect selection criterion to improve litter size due to higher heritability. However, this selection was relevant, but it did not modify litter size because of an increase in prenatal mortality. Uterine capacity has been directly related to prenatal survival, although its selection has also been unsuccessful in increasing litter size.Belabbas, R.; Ilès, I.; Argente, M.; Ezzeoug, R.; Ainbaziz, H.; García, M. (2023). Environmental and Genetic Factors Affecting Litter Size Components in Rabbits. World Rabbit Science. 31(2):117-131. https://doi.org/10.4995/wrs.2023.1868011713131

ANOGENITAL DISTANCE, SEXUAL BEHAVIOR AND PLASMA LEVELS OF TESTOSTERONE IN SYNTHETIC RABBIT BUCK

The purpose of this study was to assess the relationship between the anogenital distance measures on certain reproductive parameters such as scent marking, sexual satiety, and testosterone level. A total of 34 animals (22 rabbit bucks and 12 primiparous females) aged 6 and 7 months and with an average weight of 3458 g were used. Rabbit bucks went a behavior assessment (scent marking and sexual satiety) and blood sampling. The results indicated a mean measured anogenital distance of 22.98 ± 1.98 mm. 54.55% of the males had an anogenital distance higher than the mean anogenital distance whereas 45.45% had a lower anogenital distance. The anogenital distance, has influenced on scent marking, sexual satiety and testosterone level. Our results indicated that there is a very significant difference in the scent marking and sexual satiety and a highly significant decrease in scent marking (72.74%; p = 0.007) after satiety (51 vs 14). Males with a high number of mounting during sexual satiety test (4 to 13) had a high plasma testosterone level compared to less mounting (1 to 3) (9.75-13.5 vs 2.57-11.33ng /mL). Males with high anogenital distance have elevated testosterone levels (≥13.5 ng /mL). Our results suggest that a longer anogenital distance may predict normal male reproductive potential

Impact of Algerian date palm pollen aqueous extract on epididymal and ejaculated rabbit sperm motility during in vitro incubation

Date palm pollen (DPP) has been widely tested in vitro in preservation of spermatozoa of different farm animals except in rabbits. The objective of this study was to evaluate the effect of various concentrations (20, 40, 80 mg/mL) of DPP aqueous extract on epididymal and ejaculated rabbit spermatozoa during in vitro incubation at 37 °C during 120 min. NaCl Pollen Extender (NPE) and TRIS Base Extender (TPE) were respectively used in epididymal and ejaculated sperm preservation. Sperm motility parameters were objectively analysed by a Computer Aided Sperm Analyser (CASA). The results revealed that in epididymal sperm at 0 minute, sperm motility showed significant higher values (p ≤ 0.05) for all doses of DPP in comparison to the control group. After 30, 60 and 120 min, the motility rate was higher (p > .05) in all the experimental groups compared to the control. Concerning velocity traits (VCL and VAP), and trajectories parameters (LIN, ALH, BCF), the doses of 40 mg/mL and 80 mg/mL showed the highest values than Control. In ejaculated samples, the motility rate at 0 minute improved only with the dose of 80 mg/mL and DPP showed protective effect at all doses (20, 40, 80 mg/mL) up to 60 min of incubation. DPP enhanced spermatozoa velocity (VCL and VAP) and the trajectory of sperm (LIN, ALH, BCF) even from 20 mg/mL at any points of storage. In conclusion, aqueous extract of date palm pollen is a suitable supplement to the extender for rabbit sperm by protecting and improving sperm motility parameters.HIGHLIGHTS The addition of DPP extract improves the quality of epididymal and ejaculated rabbit sperm. The extender supplemented with 80 mg/mL of DPP in NPE has a beneficial effect on kinetic traits of epididymal sperm. Nevertheless, in TPE extender, 20 mg/mL of DPP was enough to improve sperm motility traits in ejaculated rabbit semen

A comparative study on the follicular dynamics between sexually receptive and non-receptive algerian female rabbits after mating

This histological study compared ovarian follicular growth in local Algerian breed of female rabbits between mating and the moment of the potential ovulation, in two groups of animals: 32 receptive does were mated with a buck and 25 non receptive does in which mating was assisted by manual restraint of the female. In each group, 2 to 6 rabbits were slaughtered at various stages (0, 1-2, 3-4, 5-6, 7-8, 9, 10 and 11-12 hours post coïtum (p.c)) and for each of these stages respectively 2, 4, 4, 4, 4, 4, 4, and 6 receptive rabbits and 2, 4, 4, 3, 4, 2, 2 and 4 non-receptive rabbits. In receptive rabbits, the precursor signs of the ovulation appear from the fourth hour p.c: capillary lumina dilation, a slight oedema appear ed in the theca interna region which becomes prominent two hours later. At eight hours p.c the ovum and its immediately surrounding cells were practically floating free in the folliculi liquor. In addition to the oedema in the theca interna layer, an oedema just below the surface epithelium often appeared. Before rupture, the oedema in the apex had almost disappeared and the follicle wall was very thin in this region. An ovulation is observed at 10 hours p.c. Between ten and twelve hours p.c, only four on the six studied receptive does have ovulated and showed onl y one ruptured follicles. At different stages, the non-receptive ovarian female rabbits presented many atretic and healthy follicles. The oedema in the theca interna appeared in only one rabbit from 6 hours p.c. For a majority of preovulatory follicles, ovum lost their spherical shape and presented signs of degeneration. On non-receptive does, no ovulation was observed till 12 hours p.c.These results illustrate the difficulty of a non-receptive does to ovulate and suggest for receptive does, an ovulation asynchrony and an interval between mating and ovulation often greater than 12 hours. Further longer studies will be necessary to precisely describe the follicular grow th on receptive and non-receptive rabbit does of the Algerian local population

Growth performances, carcass traits, meat quality, and blood metabolic parameters in rabbits of local Algerian population and synthetic line

Aim: The objective of this work was to study the growth performance, slaughter traits, meat quality, and metabolic profile in rabbits of local Algerian population and a synthetic line. Materials and Methods: In total, 120 weaned rabbits were used (60 per group). Growth traits were recorded from weaning (35 days) to slaughter (91 days). At slaughter, carcass traits, meat quality, and metabolic profiles were measured. Results: The synthetic line showed heavier total weight and faster daily weight gain than the local population (+15% and +19%, respectively), better feed conversion (3.92 vs. 4.81 g/g), and heavier weight of cold carcass, and perirenal fat (+15%). No differences were found between the two groups in dressing out percentage, muscular pH, weight of liver, or scapular fat. Wider intestinal villi were found in the synthetic line (+20%, p<0.0001) allowing better absorption surface in this line. The synthetic line also showed higher fat content (3.41% vs. 2.22%, p<0.0001) in the meat and lower protein content (22.02% vs. 18.98%, p=0.0002). Glucose level was 19% higher in the local population than in the synthetic line. Conclusion: The synthetic line is well adapted to the local conditions of Algeria. This line has shown better growth, daily gain, and feed conversion, due to its better intestinal absorption surface

Effect of an Extender Enriched with Algerian Date Palm Pollen on Chilled Semen Characteristics of Rabbit Bucks at Different Ages

[EN] In the present study, we evaluated the effect of various concentrations of date palm pollen (DPP) aqueous extract on rabbit sperm during storage at 4°C for 48 h. Semen was collected from old and young rabbit bucks using an artificial vagina and initially evaluated for sperm quality. The sperm were diluted in Tris buffer supplemented with (20, 40, 80 mg/mL) of DPP aqueous extract. The extended samples were stored at 4°C for 48 h. Sperm motility and motion kinetics were assessed after 2, 4, 24 and 48 h of storage. At each time, an aliquot was frozen for the analytical evaluation of thiobarbituric acid reactive substances (TBARS) (lipid peroxidation) and tocols (vitamin E). Proximate composition, antioxidant and sugar content were evaluated in DPP. The results showed that DPP was characterised by a high proportion of protein (27.10%) and ash (18.43%), whereas the lipid fraction was very low (0.51%) and total sugar was also high (16.25 g/100 g of fresh matter, f.m.). Regarding the antioxidants content, the sum of tocols showed a total value of 26.48 mg/g f.m. The total polyphenols content was 5.01 mg gallic acid equivalents/g f.m, and polyunsaturated fatty acids was around 30%. Date palm pollen extract had a dose-dependent effect on sperm parameters (curvilinear velocity [VCL] mainly) of old rabbit, although a null or negative effect was recorded at doses &gt;DPP40. Conversely, in optimal conditions (i.e. young rabbit semen), the addition of pollen had no effect on sperm traits (motility and VCL). The progressive increase in DPP, despite providing sperm with an additional amount of tocols, also caused higher tocol consumption and an increase in lipid oxidation. In particular, DPP80 increased the TBARS level in sperm of both rabbit ages. The better trend was found in DPP20, where the tocol consumption figures were 10.46 % and 15.28 %, respectively, in old and young bucks, and the lipid oxidation was lower compared to the higher doses of DPP. In conclusion, the findings of this study demonstrated that supplementation of DPP extract to Tris buffer extender enhanced chilled rabbit semen traits only if administered in old rabbit semen at concentration lower than 40 mg/mL.Laghouati, A.; Belabbas, R.; Mattioli, S.; Dal Bosco, A.; Benberkane, A.; Bravi, E.; Sileoni, V.... (2023). Effect of an Extender Enriched with Algerian Date Palm Pollen on Chilled Semen Characteristics of Rabbit Bucks at Different Ages. World Rabbit Science. 31(2):133-145. https://doi.org/10.4995/wrs.2023.1870313314531

Genetic correlations for reproductive and growth traits in rabbits

The objective of this study was to obtain heritability estimates for reproductive (litter size at birth, number born alive, litter size at weaning) and growth traits (individual weaning weight, individual weight at the end of the fattening period), then determine the genetic correlation between them in a synthetic rabbit line. A total of 805 females, 3242 parities, and 18 472 growth records were measured from 2006 to 2017. A pentavariate animal model was used with reproductive and growth traits. Heritability ranged from 0.025 to 0.126 for reproductive traits and from 0.033 to 0.059 for growth traits. These traits showed a large coefficient of variation (from 32% to 56% for reproductive traits and from 21% to 28% for growth traits). The repeatability of reproductive traits was low and the common litter effect for growth traits was the most important component of total variance. The genetic and phenotypic correlations between reproductive and growth traits were high and negative, especially with weight at weaning (−0.848, −0.922, and −0.854 for litter size at birth, number born alive, and litter size at weaning, respectively). In conclusion, because of the high negative correlation between reproductive and growth traits, both reproductive and growth traits should be selected in independent lines and the response to selection should be due mainly to the high coefficient of variation of the traits.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Genetic Analyses of Rabbit Survival and Individual Birth Weight

Genetic parameters of kit survival traits and birth weight were estimated on ITELV2006 synthetic line aimed at improving kit survival using a multiple trait linear and threshold model. Data on 1696 kits for survival at birth and at weaning, as well as individual birth weight and litter size were analysed. Genetic effects of kit survival traits and birth weight were estimated based on threshold and Gaussian models, respectively, using a Bayesian approach. The statistical model included, as fixed effects, parity, lactation status, season of farrowing, nest status, cannibalism in kit, place of kit&rsquo;s birth in the cage and gender, and adjustment for litter size. Posterior means of heritabilities for direct genetic effects of survival at birth and the entire nursing period, as well as birth weight, were 0.018, 0.023, and 0.088, respectively, and were increased when adjusted for litter size to 0.021, 0.027 and 0.146. Genetic correlation between survival traits was zero. Therefore, these traits can be treated genetically as different traits. Genetic correlation between direct effects of survival at birth and birth weight showed positive, but low, value (+0.134) and was increased to +0.535 when the traits were adjusted for litter size. No genetic correlation was found between survival at weaning and birth weight. These magnitudes of genetic parameter estimates suggested that there is substantial potential for the genetic improvement of kit survival at birth through selection for birth weight