Método minimamente invasivo para castração de machos bovinos: impactos sobre a dor e inflamação

Abstract

Reproductive activity, eliminating aggressive behavior and sodomy, thus improving fat deposition and carcass termination in castrated calves. Over the last years, costumers became increasingly concerned about animal welfare and the use of appropriate methods to manage animals. The objectives of this study were to determine the degree of discomfort caused by castration through surgery and intratesticular injection (IIT) on parameters of pain and inflammation in calves. In experiment 1, 27 calves were used, with up to 20 days of age and 36 kg of live weight. Calves were split in three distinct castration methods: control (non-castrated); surgically castrated (CC). and submitted to chemical castration through IIT of 20% NaCl. Blood samples were collected at distinct moments after the procedures (0, 24, 48, 72 and 96 h) to determine the serum levels of acute phase protein paraoxanase (PON1). The temperature in the inner corner of the eye was determined by thermography, at the same periods. Scrotal temperature was measured 30 s before the procedures (D0), at the time of the procedures (D1) and at three periods after the procedures; at 60 s (D2); at 24 h (D3); and at 48 h (D4), also through thermography. In experiment 2, the serum cortisol levels were compared among the same castration methods, in 24 calves (4-15 d of age). Blood samples were collected at the time of the procedure and also at 30 and 60 min after. In experiment 1, the temperature in the inner corner of the eye (38 - 39⁰C, in average) did not differ among methods (P>0.05). Scrotal temperature was greater at D1for CC than for the other groups (P<0.05), with subsequent increase at D4 for calves in CC and IIT, compared to the control (P<0.05). No difference among methods (P>0.05) was observed for serum levels of PON1. In experiment 2, serum cortisol levels did not differ across methods (P>0.05), but a method per period interaction indicated that cortisol levels increased in CC after 30 min and remained stable up to 60 min, although cortisol levels for calves in IIT were greatest after 30 min, declining over time after that. None of the tested methods induced relevant inflammatory reaction capable to alter systemic markers of pain and inflammation.