title: Relationship between cortisol and acute phase protein concentrations in female rabbits.
abstract: Rabbit meat production in Europe is usually based on a semi-intensive system, in which lactation and gestation overlap. The demands of lactation and pregnancy are likely to be relatively stressful for female rabbits and may compromise the immune system and reproductive performance. The present study was designed to characterise circulating levels of cortisol, haptoglobin (Hp), C-reactive protein (CRP), and serum amyloid A (SAA) in non-lactating and lactating female rabbits at first and second mating, and to determine whether any relationship exists between these biomarkers and litter size. Serum cortisol concentrations were at their greatest (mean ± SEM = 39.5 ± 3.9 nmol/L) in animals at the end of lactation. However, after weaning, cortisol concentrations were not significantly different compared to nulliparous females (19.9 ± 3.6 vs. 16.3 ± 2.2 nmol/L, respectively). The highest concentrations of circulating Hp (0.14 ± 0.01 g/L) were seen in early lactating primiparous females, and lower in nulliparous females and in rabbits after weaning. In contrast, nulliparous female rabbits showed the highest plasma CRP values (13.1 ± 1.1 mg/L). No significant differences were found for SAA. Nulliparous females had smaller litter sizes than early lactating and non-lactating primiparous female rabbits. CRP and SAA showed a positive correlation (r = +0.24, P = 0.011) and were negatively related to litter size (r = -0.23, P = 0.017 and P = 0.032, respectively). Cortisol and Hp were not related to CRP, SAA, nor to litter size. These results suggest a closer association between the mechanisms that regulate release of CRP and SAA, compared to those that regulate Hp production. Thus, lactation is associated with changes in several stress biomarkers. CRP and SAA might be more useful for evaluating animal welfare and for predicting subsequent reproductive performance of female rabbits.
authors.affiliation: Departamento de Tecnología Agroalimentaria, Universidad Miguel Hernández de Elche, Ctra de Beniel km 3.2, 03312 Orihuela, Spain. Electronic address: mj.argente@umh.es.
authors.forename: María-José
authors.initials: MJ
authors.lastname: Argente
authors.affiliation: Departamento de Tecnología Agroalimentaria, Universidad Miguel Hernández de Elche, Ctra de Beniel km 3.2, 03312 Orihuela, Spain.
authors.forename: María de la Luz
authors.initials: Mde L
authors.lastname: García
authors.affiliation: Departamento de Tecnología Agroalimentaria, Universidad Miguel Hernández de Elche, Ctra de Beniel km 3.2, 03312 Orihuela, Spain.
authors.forename: Virginia
authors.initials: V
authors.lastname: Birlanga
authors.affiliation: Departamento de Tecnología Agroalimentaria, Universidad Miguel Hernández de Elche, Ctra de Beniel km 3.2, 03312 Orihuela, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Muelas
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism*; D000818:Animals; D005260:Female; D006854:Hydrocortisone / Q000097:blood*; D007774:Lactation / Q000502:physiology; D010298:Parity; D011247:Pregnancy; D011817:Rabbits / Q000097:blood / Q000502:physiology*; D012621:Seasons
chemical_list: D000209:Acute-Phase Proteins; D006854:Hydrocortisone
keywords: C-reactive protein; Cortisol; Haptoglobin; Litter size; Serum amyloid A