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

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.

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References:

Arrington L.R., Kelley K.C. 1984. Producción y Biología de los Conejos Domésticos. Hemisferio Sur. Buenos Aires. p253.

Argente M.J., García M.L., Birlanga V., Muelas R. 2014. Relationship between cortisol and acute phase protein concentrations in female rabbits. The Veterinary Journal, 202: 172-175. https://doi.org/10.1016/j.tvjl.2014.07.020

Arias-Álvarez M., García-García M.R., Rebollar P.G., Revuelta L., Millán P., Lorenzo P.L. 2009. Influence of metabolic status on oocyte quality and follicular characteristics at different post-partum periods in primiparous rabbit does. Theriogenology, 72: 612-623. https://doi.org/10.1016/j.theriogenology.2009.04.017

Castellini C., Dal Bosco A., Mugnai C. 2003. Comparison of different reproductive protocols for rabbit doe: effect of litter size and re-mating interval. Livestock Production Science, 83: 131-139. https://doi.org/10.1016/S0301-6226(03)00070-8

Castellini C. 2007. Reproductive activity and welfare of rabbit does. Ital. J. Anim. Sci., 6: 743-747. https://doi.org/10.4081/ijas.2007.1s.743

De la Fuente L.F., Rosell J.M. 2012. Body weight and body condition of breeding rabbits in commercial units. J. Anim. Sci., 90: 3252-3258. https://doi.org/10.2527/jas.2011-4764

Freeman M.E., Kanyicska B., Lerant A., Nagy G. 2000. Prolact in: st ructure, funct ion, and regulat ion of secretion. Physiol. Rev. , 80: 1523-1631. https://doi.org/10.1152/physrev.2000.80.4.1523

Fuchs A.R., Cubile L., Dawood M.Y., Jørgensen F.S. 1984. Release of Oxytocin and Prolactin by Suckling in Rabbits throughout Lactation. Endocrinology, 114: 462-469. https://doi.org/10.1210/endo-114-2-462

González-Mariscal G., Díaz-Sánchez V., Melo A.I., Beyer C., Rosenblatt J.S. 1994. Maternal beehavior in New Zealand White Rabbis: quant i f icat ion of somatic events, motor patterns and steroid plasma levels. Physiol. Behav., 55: 1081-1089. https://doi.org/10.1016/0031-9384(94)90391-3

González-Mariscal G., Lemus A.C., Vega-González A., Aguilar-Roblero A. 2013. Litter size determines circadian periodicity of nursing in rabbits. Chronobiol. Int., 30: 711-718. https://doi.org/10.3109/07420528.2013.784769

González-Mariscal G., Caba M., Martínez-Gomez M., Bautista A., Hudson R. 2016. Mothers and offspring: the rabbit as a model system in the study of mammalian maternal behavior and sibling interactions. Horm. Behav., 77: 30-41. https://doi.org/10.1016/j.yhbeh.2015.05.011

González-Redondo P., Negretti P., Finzi A. 2010. Adoption of kits at different litter sizes in an alternative rabbit rearing system. Agrociencia, 44: 275-282.

Hudson R., Distel H. 1989. Temporal pattern of suckling in the rabbit pups: a model of circadian synchrony between mother and young. Res. Per. Med., 9: 83-102.

Jilge B., Kuhnt B., Landerer W., Rest S. 2000. Circadian thermoregulation in suckling rabbit pups. J. Biol. Rhythm., 15: 329-335. https://doi.org/10.1177/074873000129001431

Kant G.J., Lenox R.H., Bunnell B.N., Mougey E.H., Penington L.L., Meyerhoff J.L. 1983. Comparison of stress response in male and female rats: Pituitary cyclic AMP and plasma prolactin, growth hormone and corticosterone. Psychoneuroendocrinology, 8: 421-428. https://doi.org/10.1016/0306-4530(83)90021-5

Lebas F. 1972. Effect de la simultanéité de la lactation et de la gestation sur les performance laitieres chez la lapine . Ann. Zootec. , 21: 129-131.

https://doi.org/10.1051/animres:19720111

Lebas F., Marionnet D., Henaff R. 1991. La Production du Lapin. Tec & Doc Lavoisier. Association Francaise de Cuniculture. París. 214.

Lincoln D.W. 1974. Suckling: a time constant in the nursing behaviors of the rabbit. Phisiol. Behav., 13: 711-714. https://doi.org/10.1016/0031-9384(74)90247-9

Maertens L. 2010. Feeding systems of intensive Productions. In: Nutrition of the rabbit, 2nd edition. C. de Blas and J. Wisseman eds. © CAB International 2010. 253-266. https://doi.org/10.1079/9781845936693.0253

McNeilly A.S., Friessen H.G. 1978. Prolactin during pregnancy and lactation in the rabbit. Endocrinology, 102: 1548-1554. https://doi.org/10.1210/endo-102-5-1548

Minuti A., Bani P., Piccioli-Cappelli O., Uboldi O., Bacciu N., Trevisi E. 2015. Metabolic and biochemical changes in plasma of the periparturient rabbit does with different litter size. Animals, 9: 614-621. https://doi.org/10.1017/S1751731114002675

Mocé M.L., Santacreu M.A., Climent A., Blasco A. 2004. The effect of divergent selection for uterine capacity on prenatal survival in rabbits: maternal and embryonic genetic effects. J. Anim. Sci., 82: 68-73. https://doi.org/10.2527/2004.82168x

Muelas R., Cano P., García M.L., Esquifino A., Argente M.J. 2008. Influence of FSH, LH and Prolactin on the components of litter size in rabbit does. In Proc.: 9th World Rabbit Congress, June 10-13, Verona Italy. 405-409.

Pascual J.J., Savietto D., Cervera C., Baselga M. 2013. Resources allocation in reproductive rabbit does: a review of feeding and genetic strategies for suitable performance. World Rabbit Sci., 21: 123-144. https://doi.org/10.4995/wrs.2013.1236

Poigner J., Szendrő Z., Lévai A., Radnai I., Biró-Nemeth E. 2000. Effect of birth weight and litter size on growth and mortality in rabbits. World Rabbit Sci., 8: 17-22. https://doi.org/10.4995/wrs.2000.413

Rebollar P.G., Milanés A., Pereda N., Millán P., Cano P., Esquifino A.I., Villarroel M., Silván G., Lorenzo P.L. 2006. Oestrus synchronisation of rabbit does at early post-partum by doe-litter separation or ECG injection: Reproductive parameters and endocrine profiles. Anim. Reprod. Sci., 93: 218-230. https://doi.org/10.1016/j.anireprosci.2005.06.032

Rebollar P.G., Bonanno A., Di Grigoli G., Tornambe G., Lorenzo P.L. 2008. Endocrine and ovarian response after a 2-day controlled suckling and eCG treatment in lactating rabbit does. Anim. Reprod. Sci., 104: 316-328. https://doi.org/10.1016/j.anireprosci.2007.02.018

Rebollar P.G., Pérez-Cabal M.A., Pereda N., Lorenzo P.L., Arias-Álvarez M., García-Rebollar P. 2009. Effects of parity order and reproductive management on the efficiency of rabbit productive systems. Livest. Sci. J., 121: 227-233. https://doi.org/10.1016/j.livsci.2008.06.018

Rebollar P.G., Dal Bosco A., Millán P., Cardinali R., Brecchia G., Sylla L., Lorenzo P.L., Castellini C. 2012. Ovulating induction methods in rabbit does: The pituitary and ovarian responses. Theriogenology, 77: 292-298. https://doi.org/10.1016/j.theriogenology.2011.07.041

Rebollar P.G., García-García R.M., Arias-Álvarez M., Millán P., Rey A.I., Rodríguez M., Formoso-Rafferty N., de la Riva S., Masdeu M., Lorenzo P.L., García-Rebollar P. 2014. Reproductive long-term effects, endocrine profiles of rabbit does fed diets supplemented with n-3 fatty acids. Anim. Reprod. Sci., 146: 202-209. https://doi.org/10.1016/j.anireprosci.2014.02.021

Rodríguez M., García-García R.M., Arias-Álvarez M., Millán P., Febrel N., Formoso-Rafferty N., López-Tello J., Lorenzo P.L., Rebollar P.G. 2018. Improvements in the conception rate, milk composition and embryo quality of rabbit does after dietary enrichment with n-3 polyunsaturated fatty acids. Animal, 12: 2080-2088. https://doi.org/10.1017/S1751731117003706

SAS Institute. 2001. SAS/STAT® User's Guide (Release 8.2). SAS Inst. Inc., Cary NC, USA.

Seggie J.A., Brown G.M. 1975. Stress response patterns of plasma corticosterone, prolactin and growth hormone in the rat, following handling or exposure to novel environment. Can. J. Physiol. Pharmacol., 53: 629-637. https://doi.org/10.1139/y75-087

Szendrő Z., Maertens L. 2001. Maternal effect during pregnancy and lactation in rabbits (a review). Acta Agraria Kaposváriensis, 5: 1-21.

Ubilla E., Rebollar P.G. 1995. Influence of the postpartum day on plasma estradiol-17beta levels, sexual behavious, and conception rate, in artificially inseminated lactating rabbits. Anim. Reprod. Sci., 38: 337-344. https://doi.org/10.1016/0378-4320(94)01366-T

Ubilla E., Alvariño J.M.R., Esquifino A., Agrasal C. 1992. Effects of induction of parturition by administration of a prostaglandin F2α analogue in rabbits: possible modification of prolactin, LH and FSH secretion patterns. Anim. Reprod. Sci., 27: 13-20. https://doi.org/10.1016/0378-4320(92)90066-M

Ubilla E., Rebollar P.G., Pazo D., Esquifino A., Alvariño J.M.R. 2000a. Effects of doe-litter separation on endocrinological and productivity variables in lactating rabbits. Livest. Prod. Sci., 67: 67-74. https://doi.org/10.1016/S0301-6226(00)00196-2

Ubilla E., Rebollar P.G., Pazo D., Esquifino A., Alvariño J.M.R. 2000b. Pituitary and ovarian response to transient doelitter separation in nursing rabbits. J. Reprod. Fertil., 118: 361-366. https://doi.org/10.1530/jrf.0.1180361

Xiccato G. 1996. Nutrition of lactating does. 6th World Rabbit Congress, 9-12 July 1996, Toulousse, France. 1. 29-47.

Xiccato G., Bernardini M., Castellini C., Dalle Zote A., Queaque P.I., Trocino A. 1999. Effect of post-weaning feeding on the performance and energy balance of female rabbits at different physiological states. J. Anim. Sci., 77: 416-426. https://doi.org/10.2527/1999.772416x

Xiccato G., Trocino A. 2010. Energy and protein metabolism and requirements. In: De Blas, C., Wiseman, J. (Eds.), Nutrition of the Rabbit., 2nd ed. CABI, Wallingford, Oxfordshire, UK. 83-118. https://doi.org/10.1079/9781845936693.0083

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