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Performance, carcass and meat quality traits of Nellore bulls immunocastrated at different ages

Douglas Henrique Silva de Almeida  ; Fernanda Macitelli Benez ; Janaina da Silva Braga ; Mateus Paranhos da Costa
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Castrated bulls have a differentiated payment at Brazilian meat market in function of the better meat and carcass quality through increased subcutaneous fat deposition. However, traditional surgical castration profoundly affects the animal welfare. In this context, immunocastration can be recommended, although the farmers still have doubts with regard to age at immunocastration, mainly because cattle raised only in extensive production system frequently ages without good weight and subcutaneous fat coverage. We aimed to assess the effects of immunocastration at different ages on performance and carcass and quality traits of Nellore bulls. 290 bulls were imunnocastrated (IC) according to Bopriva(R) protocol (Zoetis Animal Health) before the beginning of the finishing period, and others 290 remained not IC as controls animals (CN). All animals were finished in two groups (IC; CN) during 73 days in a commercial semi-confinement with pasture, water and concentrated diet (2.4% of liveweight, twice a day). Initially, the animals were chosen visually by different ages and were equally divided in two groups (IC; CN). The age was confirmed at the slaughter line by the direct visualization of the permanent incisive teeth (p.i.t), being: IC1 and CN1 - from 2 to 4 p.t.i; 24 to 36 months old; N= 146; N=145, respectively and IC2 and CN2 - from 6 to 8 p.t.i; above 42 months old; N = 144; N = 145, respectively. The variables assessed were: average daily gain (ADG), subcutaneous fat coverage (SFC), total number of bruises (BRU) and 24 hours meat pH. Regardless of age CN performed better than IC (P < 0.05) showing approximately 15% higher ADG. Comparing the IC, IC2 showed higher (P < 0.05) ADG than IC1 (IC1 = 1.15 ? 0.32; CN1 = 1.36 ? 0.41; IC2 = 1.21 ? 0.39, CN2 = 1.43 ? 0.49 kg/day). No difference between IC1 and IC2IC was observed for SFC, BRU and meat pH (P > 0.05). However SFC was higher (P < 0.05) in animals from IC1 and IC2 compared with CN1 and CN2, respectively (IC1 = 2.72 ? 0.54 and CN1 = 2.29 ? 0.46; IC2 = 2.85 ? 0.57 and CN2 = 2.48 ? 0.49). We concluded that older imunnocastred Nellore bulls perform better than the younger ones and regardless of age the immunocastration was effective in improving carcass quality due higher thickness of subcutaneous fat coverage.