Immune response on rabbit does of different genetic types subjected to reproductive, environment and immunologic challenges

• Autores: Selena Ferrian
• Directores de la Tesis: Juan José Pascual Amorós (dir. tes.), Juan Manuel Corpa Arenas (dir. tes.)
• Lectura: En la Universidad Cardenal Herrera-CEU ( España ) en 2013
• Idioma: inglés
• Tribunal Calificador de la Tesis: Enrique Blas Ferrer (presid.), María Isabel Guillén Salazar (secret.), Carles Ubeda Morant (voc.), Torben Larsen (voc.), Joan M. Rosell Pujol (voc.)
• Materias:
  • Ciencias agrarias
    • Producción animal
      • Reproducción
    • Ciencias veterinarias
      • Genética
      • Inmunología
• Enlaces
  • Tesis en acceso abierto en: Repositorio Institucional CEU
• Resumen

  • Rabbit health may be considered one of the main handicaps on commercial farms. The overall objective of this Ph.D. was to study the immune response on rabbit does of different genetic types subjected to reproductive, environment and immunologic challenges and its relationship with body condition. The effect of selection was studied by using different genetic types. The current evidence for trade-offs between reproduction and longevity is reviewed, and a framework relating immune response, body condition and selection criterium is presented. In the first study, the main objectives were to compare the peripheral blood lymphocyte populations of multiparous rabbit does under two reproductive rhythms [insemination at 11 days post partum (dpp) and weaning at 28 dpp, insemination at 25 dpp and weaning at 42 dpp], and to assess the influence on those of kits. Additionally, the perirenal fat thickness of does was also measured at partum and weaning to observe if body condition correlates with lymphocyte populations. During whole lactation, counts of total, CD5+, CD4+ and CD8+ lymphocytes of females were generally lower with weaning at 42 dpp compared to 28 dpp. Moreover, counts of total, B and CD5+ lymphocytes in rabbit does weaned at 42 dpp correlated to their body condition, contrary to that observed in rabbit does weaned at 28 dpp. Some correlations between lymphocyte counts in both groups of does and weaning rabbits were observed. At weaning, those young rabbits weaned at 42 dpp had a lower number of CD4+ lymphocytes than those weaned at 28 dpp. In conclusion, the 42 ddp rabbit does presented a lower number of total lymphocytes and lymphocyte subsets during lactation and at weaning, as well as lesser capacity of adjustment during the gestation¿lactation cycle. In the second study, the effect of selection for reproduction (V line selected for litter size at weaning) or foundation for reproductive longevity (the LP line) was investigated, under normal and heat stress conditions. After the first parturition, animals were randomly distributed in the experimental housing systems until the second parturition. The cross between two maternal lines was compared with same cross but 20 generations earlier using a cryopreserved control population. To evaluate the possible correlation between the energy balance and the immunological status of females, daily feed intake (DFI) during lactation week 2 and perirenal fat thickness (PFT) on 14 dpp were controlled by ultrasound. Housing under heat stress conditions reduced the B lymphocytes counts in female rabbits. The highest lymphocytes population value in blood (total, T CD5+, CD4+ and CD8+) was noted at the first parturition, while the B lymphocytes count was lower at the second parturition. Selection for litter size at weaning (V females) reduced the average counts of total and B lymphocytes in blood mainly because these populations in V36 females continuously lowered from the first to the second parturition under normal housing conditions. Thus, more selected females (V36) at the second parturition showed lower counts in blood for total, T CD5+ and CD25+ lymphocytes. The main differences in blood counts between V36 and V16 females disappeared when housed under heat stress conditions, except for T CD5+ and CD25+, which increased in the V16 vs. V36 females on day 10 post-partum. Under normal conditions, no differences between LP and V36 females were found for most lymphocyte populations; only higher counts were noted in CD25+ for LP females. However, the lymphocytes counts (especially total and T CD5+) of LP females increased under heat vs. normal conditions when lymphocytes populations presented the lowest values (second parturition), while V36 females¿ counts remained invariable. Positive correlations were found between feed intake and females¿ perirenal fat thickness with B lymphocytes counts in the blood of primiparous rabbit females in the week 2 of lactation. These results indicate that selection for litter size at weaning might diminish their immune system¿s response and adaptation capacity, while the foundation for reproductive longevity criteria leads to more robust rabbit females as they present greater modulation under heat stress conditions when the immune system is affected. In the third study to evaluate differences in maternal lines to the immune response of reproductive rabbit does, rabbits does (1) founded for the same criteria of the previous study were used. Females were subjected to three different reproductive effort levels: post-partum (PP) mating at first lactation and 9 kits during the second; post-weaning (PW) mating at first lactation and 9 kits during the second; and PW mating at first lactation and 5 kits during the second. At second weaning (30 days PP), an acute response was induced by intravenous infusion of lipopolysaccharide (LPS). LP females seemed to be lower affected during the hyper-acute phase than V females, showing lower plasma glucose content at 1.5 h post infusion (pi) and rectal temperature at 6 h pi; and showed higher ulterior immune response, with higher levels of c-reactive protein at 48 h pi and haptoglobin in plasma from 24 h pi. Survival test conferred a higher risk of culling for V than for LP females during the first hours after challenge. Moreover, the advantage in terms of survival rate of the LP over the V line came exclusively from females mated after first weaning (PW), which were also the main group responsible for the increase of NEFA in blood after 6 h pi. These results may suggest that, regarding immune response to LPS challenge, foundation by hyper-longevity productive criteria lead to obtain a more robust population of rabbit does, characterized by improved response ability. In conclusion, from results of the three studies of this thesis may be conclude that, it seems to have an evident relationship between the body condition and health status of reproductive rabbit does, as clear positive correlations have been observed between body condition and main lymphocyte population counts in the first two studies, and NEFA levels in blood seem to be the only plasma trait related to female survival in the immunological challenge developed in the third study. Thus, these results confirm the initial hypothesis of this thesis, where body condition is proposed to play a mediating role entailing that, for animals under same production and genetic level, the better body condition, the better immune response.