雞遮眼板提升臺灣土雞動物福祉之田間試驗

Abstract

土雞產業是台灣重要的特色家禽產業。然而，生產模式多以長時間平飼進行，使得土雞於飼養過程中經歷接近或達性成熟的生長階段，在飼養密度上升與睪固酮分泌量提升的作用下，因此頻繁引發啄羽與打鬥等攻擊行為。攻擊行為的產生，容易造成雞隻外表受損甚至引起死亡，影響農民收益；同時，處於攻擊行為威脅下的弱勢雞隻亦有動物福利受損的疑慮。 雞遮眼板乃為因應攻擊行為而研發，透過屏蔽雞隻正面雙眼立體視覺區降低雞隻空間與距離感，使攻擊行為難以完成。此外，雞遮眼板的配戴仰賴鼻環以夾住鼻孔緣的方式進行固定，並不會產生外傷，因此能不引起雞隻傷痛並免除攻擊行為所致之負面影響，是本研究欲進行探討的目標。 本研究旨在使用行為學與血液生化學作為緊迫指標以檢驗土雞動物福利，並檢測土雞之生長表現。我們假設配戴雞遮眼板能降低土雞群體間攻擊行為產生頻率，使配戴雞遮眼板組別表現較低之緊迫指標數值，並具不劣於控制組之生長表現。 先期試驗中，以控制組50隻與配戴組350隻黑羽土雞進行試驗，評估雞遮眼板之配戴條件及其對生長表現與行為表現之影響。依據鳥喙長度量測結果顯示，5 週齡起適合進行配戴，並能於 11 週齡時保有 99% 之配戴率，且雞遮眼板之材質及其煮後水體均不含塑化劑與雙酚A等物質。生長表現結果顯示，配戴雞遮眼板不影響黑羽土雞之體重與死亡率，但配戴組之體重的標準差較低，且飼料效率較高。此外，配戴組之採食行為、活動行為與攻擊行為之表現顯著低於控制組 (P < 0.05)，休息行為表現則顯著高於控制組 (P < 0.05)。兩組之自然行為表現沒有差異 (P > 0.05)。行為學研究中，以公、母各 1000 隻紅羽土雞進行試驗，並於 5 週齡時將半數雞隻進行雞遮眼板配戴，以全時錄影進行行為採樣。透過建立日間攻擊行為圖譜，歸納出紅羽土雞之攻擊行為好發於每日 05:30 ~ 07:29 及 16:30 ~ 18:29 間。依據前述時間區間進行分析，結果顯示 6 至 10 週齡時，公/母配戴組之各週齡攻擊行為頻率皆顯著低於公/母控制組 (P < 0.05)。而無論公母，配戴組與控制組其 7 及 9 週齡之血漿睪固酮濃度皆無顯著差異 (P > 0.05)，顯示雞遮眼板能在不影響睪固酮的條件下有效降低攻擊行為之發生頻率。並且，攻擊行為頻率的結果與血中異嗜球/淋巴球比值 (H/L ratio) 的結果一致，顯示紅羽土雞配戴雞遮眼板後擁有較低的緊迫程度。血液生化學研究中，以 3600 隻黑羽土雞公雞為試驗動物並平均分為六組，每組 600 隻。控制組與配戴組各有三組，其欄位於雞舍內隨機排列。三組配戴組雞隻亦於 5 週齡時進行雞遮眼板配戴，並於五、七及九週齡採集血樣作為分析樣本。本研究以血中異嗜球/淋巴球比值、促發炎反應細胞激素 (HSP-70、IL-1β、IL-9) 與急性反應期蛋白 (AGP、SAA、OVT) 作為緊迫指標。五週齡血樣分析結果顯示，配戴組與控制組於H/L ratio及各項緊迫指標之基因表現量皆無顯著差異 (P > 0.05)。七週齡時，配戴組之 H/L ratio 顯著低於控制組 (P < 0.05)，且配戴組之 HSP-70、IL-1β 及 IL-9 三項促發炎反應細胞激素之基因表現量皆顯著低於控制組 (P < 0.05)，但三項急性反應期蛋白基因表現量與控制組沒有顯著差異 (P > 0.05)。九週齡時，配戴組之 H/L ratio 略低於控制組 (P = 0.07)，而 HSP-70、IL-1β、IL-9、AGP、SAA 及 OVT 六項基因表現量皆顯著低於控制組 (P < 0.05)。基因表現量測定結果顯示，於 5 週齡配戴起始日時，不同處理組之緊迫程度相仿；於配戴雞遮眼板 2 週與 4 週後，配戴組之黑羽土雞擁有較低的緊迫程度。本研究進一步檢視六種緊迫指標之蛋白質表現量，亦得到與基因表現量相似的結果，證實了配戴雞遮眼板對於降低黑羽土雞緊迫有所助益。綜合生長表現以上述控制組與配戴組各 2800 隻紅羽及黑羽土雞的生長表現進行綜合評估，測定結果顯示，配戴雞遮眼板對於土雞的體重及體重變異係數沒有顯著影響(P > 0.05)，但有助於提升體重的整齊度 (P = 0.07)、飼料效率 (P = 0.07) 及降低死亡率 (P = 0.08)。此外，依據較佳飼料效率與低死亡率的效益進行生產費用與收益估算，顯示配戴雞遮眼板能增加土雞飼養收益。每隻配戴組雞隻與死亡率差異帶來的額外收益，以 2800 隻土雞的規模進行計算，共能帶來約 1120 ~ 7560 元新台幣之獲利。 綜合以上結果，說明雞遮眼板能在不影響睪固酮分泌的情況下降低土雞的攻擊行為表現，藉此提升動物福利。並且，由血液生化學緊迫指標數值同樣驗證了雞遮眼板能提升土雞動物福利的假設。同時，雞隻生長表現的數據顯示配戴雞遮眼板對土雞生長無不良影響。綜上所述，雞遮眼板在台灣現行的商業飼養模式中，具有可提升土雞動物福利的效益，且在實務上具可行性。

In Taiwan, country chickens are the signature product, and the slaughtered amount is accounted for 40% of the chicken meat industry. To meet the religious demands, country chickens are always slaughtered at the age beyond 11 weeks for sexually mature outlooks. However, as testosterone levels increased and the space used for each chicken decreased with age, an agonistic behavior expression rise as well. These lead to increased appearance damages and mortality thus affecting farmers’ income as well as the concern of animal welfare in the poultry industry. Chicken blinders are invented to prevent feather pecking by obstructing chickens’ forward visions. By blocking the binocular vision that functions as the stereoscopic sense, agonistic behaviors are difficult to be accomplished. In this study, we evaluated the effect of chicken blinders on alleviating social stress and promoting animal welfare on Taiwan country chickens from ethological, hematological, and growth performance standpoints. We hypothesized that wearing chicken blinders reduces agonistic behavior frequency and lessens social stress. In the preliminary study, we examined the wearing conditions of chicken blinders and the effects of wearing chicken blinders on growth performance and behavior expression in black-feathered Taiwan country chickens. Results suggested that it is ideal for wearing chicken blinders from 5 weeks of age and has a 99% attached rate at 11 week-of-age. Wearing chicken blinders did not affect the body weight and death rate although the uniformity was good and the feed efficiency was higher in the test group. The performances of the test group in ingestive behavior, active behavior, and agonistic behavior were significantly lower (P < 0.05), whereas the resting behavior performance was significantly higher (P < 0.05) than the control group. Natural behavior did not differ between the two groups (P > 0.05). In the ethological study, male and female red-feathered Taiwan country chickens were used. Chicken blinders were applied on 5 week-of-age birds. Scan sampling of agonistic behaviors was conducted. The agonistic behavior frequency in both the male and female test groups was significantly lower than those in the male/female control group throughout 6 to 10 week-of-age (P < 0.05). Results also showed that while stocking densities and testosterone levels increased with age, wearing chicken blinders did not affect testosterone levels (P > 0.05). Furthermore, the Heterophil/lymphocyte ratios of test groups were lower, for both the 7 and 9 week-of-age data of different genders (P < 0.05). In the hematological study, male black-feathered Taiwan country chickens were used. Chicken blinders were applied on 5 week-of-age. Blood sampling was executed on 5, 7, and 9 weeks of age. The H/L ratio, pro-inflammatory cytokines (HSP-70, IL-1β, IL-9), and acute phase proteins (AGP, SAA, OVT) were measured as stress indicators. The 5 week-of-age results showed that there was no significant difference in the H/L ratio and all of the gene expression data between the test groups and the control groups (P > 0.05). At 7 weeks of age, the H/L ratio and the gene expressions of HSP-70, IL-1β, and IL-6 in the test groups were significantly lower (P < 0.05). At 9 weeks of age, the H/L ratio of the test groups was slightly lower (P = 0.07). The expression levels of HSP-70, IL-1β, IL-6, AGP, SAA, and OVT were significantly lower in the test groups (P < 0.05). We further determined the protein levels of the six stress indicators. They were identical to the gene expression data. The results of overall growth performance showed that wearing chicken blinders had no effect on the body weight and coefficient of variation (P > 0.05), but it contributed to slightly increased uniformity (P = 0.07), feed efficiency (P = 0.07), and decreased death rate (P = 0.08). Based on the better feed efficiency and lower death rate, the cost benefit analysis was calculated. It showed that wearing chicken blinders could increase the income. Based on the ethological results, it is suggested that wearing chicken blinders can reduce agonistic behavior expression without affecting testosterone secretion. Furthermore, the hematological data supported the hypothesis that wearing chicken blinders would promote animal welfare. Simultaneously, overall growth performance results revealed that wearing chicken blinders caused no negative impacts. In conclusion, wearing chicken blinders is practically feasible in a commercial feeding system of Taiwan country chickens.