RESUMO
BACKGROUND: Surgical castration is still practiced in many EU countries to avoid undesirable aggressive behavior and boar taint in male pigs. However, evidence shows that castration is painful and has a detrimental influence on pig health. This study investigated the clinical and productive effects of surgical castration in the suckling period. A total of 3696 male pigs, 3 to 6 days old, comprising of 721 litters from two different farms were included in the study. Within each litter, half of the males were kept as intact males (IM) and half were surgically castrated (CM). Surgical castration was conducted by a trained farmer. Average daily gain (ADG), body weight at weaning (BWW), percentage of pre-weaning mortality (PWM) and antibiotic usage were measured. Pig major acute phase protein (PigMAP) serum concentrations were analyzed prior to castration, and on days 1 and 10 after castration. Productive performance data were analyzed using a linear mixed model. Mortality and percentage of pigs treated with antibiotics were analyzed using the Fisher's exact test. RESULTS: No overall differences in BWW and ADG were observed between the two groups. However, differences were observed when the same effects were analyzed in the 25% lightest, 50% medium and 25% heaviest pigs at birth. PWM was higher in CM than in IM groups (6.3% vs 3.6%; p < 0.001), especially in the light (12.2% vs 6.2%; p = 0.02) and in the medium (5.5% vs 2.7%; p = 0.04) weight groups. In the heaviest pigs group PWM was not affected by castration, but IM tended to show higher ADG (p = 0.06) and showed higher BWW (8.0 kg vs 7.8 kg; p = 0.05) than CM. There were no differences in percentage of pigs treated with antibiotics between the two groups (5.8% vs 5.8%; p = 0.98) in this study. Furthermore, PigMAP was increased in CM the day after castration (0.944 mg/ml vs 0.847 mg/ml; p = 0.025), but there was no difference between CM and IM groups at day 10. CONCLUSIONS: Surgical castration has a negative impact on production in the suckling period because it causes an increase in PWM, especially in pigs in the three lower quartiles for body weight, and negatively affects the BWW in pigs born in the highest quartile for body weight.
RESUMO
The immune response induced by intramuscular administration of a commercial inactivated Mycoplasma hyopneumonie whole-cell vaccine (Suvaxyn(®)MH One) was investigated in conventional M. hyopneumoniae-free pigs. The animals were assigned randomly to two groups: non-vaccinated and vaccinated. Pigs in the vaccinated group were injected intramuscularly with the vaccine at 7 days of age, whereas non-vaccinated pigs received physiological saline solution (PBS). Pigs were euthanized and necropsied at 30, 36 and 58 days of age. Blood, bronchoalveolar lavage (BAL) fluid, spleen, lung and bronchial lymph nodes (BLN) were collected. Serum and BAL fluid were tested for the presence of antibodies by ELISA. Monomorphonuclear cells from the peripheral blood and tissues were isolated to quantify the T cell subsets by flow cytometry, and cytokine production by ELIspot and ELISA. Antibodies against M. hyopneumoniae were detected in serum of most vaccinated pigs at 30 days of age. M. hyopneumoniae specific IgG, IgM and IgA were detected in BAL fluid from vaccinated animals, but not from control animals. Significantly higher numbers of IL-12 secreting cells were observed in the lung at day 58 in the vaccinated than in the non-vaccinated group (p<0.05). The number of IL-10 secreting cells from BLN was also higher in the vaccinated group at day 58 (p<0.05). After restimulation in vitro, lymphocytes from BLN and lungs secreted significantly higher levels of IL-12 in the vaccinated group at day 58. These results show that the vaccine induced both systemic and mucosal cellular and humoral immune responses.
