溫熱環(huán)境對母豬生產(chǎn)性能的影響及其調(diào)控技術(shù)研究進展

曾雅瓊，王浩,2，劉作華，李爽，蒲施樺,2，龍定彪,2

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溫熱環(huán)境對母豬生產(chǎn)性能的影響及其調(diào)控技術(shù)研究進展

曾雅瓊1，王浩1,2，劉作華1，李爽1，蒲施樺1,2，龍定彪1,2

（1重慶市畜牧科學院，重慶 402460；2農(nóng)業(yè)部西南設施養(yǎng)殖工程科學觀測實驗站，重慶 402460）

生豬養(yǎng)殖業(yè)是我國農(nóng)業(yè)和農(nóng)村經(jīng)濟的支柱性產(chǎn)業(yè)之一，母豬作為生豬養(yǎng)殖場的核心豬群，其生產(chǎn)性能是決定生豬養(yǎng)殖場經(jīng)濟效益的關(guān)鍵因素。我國是世界生豬養(yǎng)殖的第一大國，能繁母豬存欄量和商品豬出欄量均超過世界總量的50%，然而，與發(fā)達國家相比，我國母豬飼養(yǎng)管理水平較低，在生產(chǎn)性能方面仍存在較大差距。實際生產(chǎn)中母豬的生產(chǎn)性能受到諸多因素的影響，主要包括母豬的營養(yǎng)攝取、機體特性、飼養(yǎng)空間環(huán)境及胎次等，其中溫熱環(huán)境是影響母豬健康和生產(chǎn)性能的重要因素之一。溫熱環(huán)境包括溫度、相對濕度、空氣流動、輻射及熱傳遞等因素，他們共同作用于動物，使動物產(chǎn)生冷或熱、舒適與否的感覺。適宜的溫熱環(huán)境有利于保障母豬的機體健康，提高其生產(chǎn)性能，反之，不適宜的溫熱環(huán)境會引起母豬的熱環(huán)境應激，破壞體熱平衡，甚至導致生產(chǎn)停止，使機體進入病理狀態(tài)，引發(fā)疾病甚至死亡。因此，掌握母豬的溫熱環(huán)境需求并采取有效的調(diào)控措施，對提高母豬生產(chǎn)性能和生豬養(yǎng)殖場經(jīng)濟效益至關(guān)重要。文章從溫熱環(huán)境對母豬的影響和溫熱環(huán)境調(diào)控技術(shù)兩個方面進行綜述，旨在為我國生豬養(yǎng)殖場母豬生產(chǎn)管理的溫熱環(huán)境調(diào)控提供理論依據(jù)和技術(shù)支撐。（1）溫熱環(huán)境對母豬的影響方面。溫熱環(huán)境對母豬的影響主要體現(xiàn)在行為、生理和生產(chǎn)性能等方面的變化。在行為方面，高溫環(huán)境下，由于側(cè)臥時母豬體表與地面的接觸面積更大，可增加機體散熱量，母豬會通過行為姿勢改變進行熱調(diào)節(jié)，如增加側(cè)臥時間、減少站立和俯臥時間，而母豬姿勢行為的頻繁改變會增加仔豬壓死率。在生理方面，熱應激時母豬會通過減少采食量、增加呼吸率和皮膚血流量等途徑來減少代謝產(chǎn)熱、增加散熱，同時母豬血液中促腎上腺皮質(zhì)激素和皮質(zhì)醇會增加、甲狀腺素降低、胰島素敏感性增加，這些生理變化會破壞母豬機體內(nèi)分泌和能量平衡，進而導致胚胎早期死亡、流產(chǎn)和泌乳量下降。在生產(chǎn)性能方面，熱應激會對母豬發(fā)情間隔、產(chǎn)仔數(shù)和泌乳量等生產(chǎn)性能造成不利影響，妊娠前期熱應激主要影響返情率和產(chǎn)仔數(shù)，妊娠后期主要影響產(chǎn)活仔數(shù)和死胎數(shù)，分娩后則主要影響仔豬存活率，環(huán)境高溫通過影響母豬的泌乳量對哺乳仔豬生產(chǎn)性能產(chǎn)生不利影響，通過影響母豬的采食量、泌乳期母豬失重和體內(nèi)生殖激素的分泌，導致母豬斷奶后發(fā)情延遲。（2）溫熱環(huán)境調(diào)控技術(shù)方面。母豬溫熱環(huán)境調(diào)控技術(shù)主要包括豬舍整體降溫和局部降溫兩種，整體降溫以“濕簾-風機”蒸發(fā)冷卻降溫技術(shù)為代表，通過風機排風造成舍內(nèi)負壓，迫使舍外未飽和的空氣流經(jīng)濕潤的多孔濕簾，引起水分蒸發(fā)吸收大量潛熱，降低進入舍內(nèi)的空氣溫度，從而達到降低舍內(nèi)溫度的目的，該技術(shù)具有設備簡單、經(jīng)濟高效的優(yōu)勢。豬舍局部降溫主要是針對豬只躺臥區(qū)地板、兩側(cè)豬欄、豬欄上方等區(qū)域進行溫度調(diào)控，主要有風管噴氣嘴蒸發(fā)冷卻、冷水覆蓋降溫和豬舍地板降溫等方式，具有降溫效果良好和節(jié)能的優(yōu)點。

母豬；溫熱環(huán)境；調(diào)控；生產(chǎn)性能

我國是世界生豬養(yǎng)殖的第一大國，生產(chǎn)母豬存欄量和商品豬出欄量均超過世界總量的50%[1]，是我國農(nóng)業(yè)和農(nóng)村經(jīng)濟的支柱性產(chǎn)業(yè)之一。母豬作為生豬養(yǎng)殖場的核心豬群，其繁殖性能是決定生豬養(yǎng)殖場經(jīng)濟效益的關(guān)鍵環(huán)節(jié)。我國的母豬管理水平與發(fā)達國家相比還存在較大差距，我國平均每頭生產(chǎn)母豬年提供商品肥豬（MSY）不超過15頭，年產(chǎn)胎次（LYS）為2.2，而歐洲、加拿大、美國等國家MYS則超過25頭，丹麥更是超過30頭，LYS則達到2.3—2.4[2]。母豬的生產(chǎn)繁殖性能由營養(yǎng)、機體特性、飼養(yǎng)環(huán)境及胎次[3-6]等多種因素共同決定，其中溫熱環(huán)境是重要影響因素之一，適宜的溫熱環(huán)境有利于保障母豬的健康狀況，提高其生產(chǎn)和繁殖性能，反之則會引起母豬的熱應激，破壞體熱平衡，甚至導致生產(chǎn)停止，使機體進入病理狀態(tài)，引發(fā)疾病甚至死亡[7-8]。因此，掌握母豬的溫熱環(huán)境需求并采取有效的調(diào)控措施，對提高母豬生產(chǎn)繁殖性能和生豬養(yǎng)殖經(jīng)濟效益至關(guān)重要。

本文以母豬為對象，以溫熱環(huán)境為影響因素，通過對國內(nèi)外相關(guān)研究成果的綜述、分類和總結(jié)，闡述了溫熱環(huán)境對母豬繁殖性能、行為習性和生理狀況等的影響，并詳細介紹國內(nèi)外母豬溫熱環(huán)境調(diào)控新技術(shù)、新方法和新設備，旨在為我國生豬養(yǎng)殖場母豬生產(chǎn)管理的溫熱環(huán)境調(diào)控提供理論依據(jù)和技術(shù)支撐。

1 溫熱環(huán)境對母豬的影響

1.1 生產(chǎn)性能

熱應激對養(yǎng)豬業(yè)的經(jīng)濟效益影響巨大，其主要表現(xiàn)為母豬生產(chǎn)性能的下降所造成的經(jīng)濟損失。據(jù)統(tǒng)計在美國由熱應激所導致的母豬經(jīng)濟損失高達4.5億美元/年[9-10]，而熱應激對母豬生產(chǎn)性能產(chǎn)生的不利影響主要體現(xiàn)在產(chǎn)仔數(shù)、仔豬成活率、泌乳量、斷奶至發(fā)情間隔等方面[11-12]，且存在生理階段差異。

熱應激對母豬產(chǎn)仔數(shù)的不利影響存在生理階段差異性：妊娠前期熱應激主要影響返情率及產(chǎn)仔數(shù)，妊娠后期熱應激主要影響產(chǎn)活仔數(shù)和死胎數(shù)，分娩后熱應激則主要影響仔豬存活率。TUMMARUK等[13]認為在妊娠早期（1—35 d）高溫應激顯著降低產(chǎn)仔數(shù)和產(chǎn)活仔數(shù)，而妊娠晚期的高溫應激（102—110 d）導致死胎率升高[14]。 TANTASUPARUK等[15]認為在妊娠前四周豬舍每日最高溫度提高1℃，窩產(chǎn)仔數(shù)降低0.07頭。BLOEMHOF等估算得出影響產(chǎn)仔數(shù)和分娩率的溫度上限閾值分別為21.7℃和19.2℃[16]，而我國南方地區(qū)夏季豬舍平均溫度在29℃以上[17-18]。李延森等[19]報道江蘇鹽城環(huán)境溫度對母豬繁殖性能的影響，夏季（7月份）最高氣溫時，母豬的總產(chǎn)仔數(shù)（10.9頭）和斷奶活仔數(shù)最低（7.65頭），胎均死胎數(shù)最高（0.49），并且溫度與返情率呈正相關(guān)，與7d發(fā)情率呈負相關(guān)。WEGNER等[8]研究了溫度（15—25℃）對夏季母豬繁殖性能的影響，發(fā)現(xiàn)配種前6d至配種后14d期間高溫顯著降低母豬窩產(chǎn)仔數(shù)（＜0.05）；產(chǎn)前4d內(nèi)的高溫環(huán)境顯著降低活仔數(shù)（＜0.05）、提高死胎數(shù)（＜0.001），環(huán)境溫度每升高1℃，窩產(chǎn)仔數(shù)減少0.03頭；分娩至產(chǎn)后12d，高溫環(huán)境顯著降低仔豬存活率（＜0.05），溫度每升高1℃，窩活仔數(shù)減少0.02頭。

環(huán)境高溫通過影響母豬的泌乳量對哺乳仔豬生產(chǎn)性能產(chǎn)生不利影響。高溫環(huán)境下，母豬通過減少采食量和增加體表皮膚的血液流量，達到降低產(chǎn)熱、增加散熱的目的，從而導致母豬乳腺合成乳汁需要的養(yǎng)分減少，降低母豬的泌乳量[20-22]。

SPENCER等[23]研究發(fā)現(xiàn)，與21℃相比，高溫環(huán)境下（32℃）母豬產(chǎn)后第第14天采食量顯著降低（7.97kg vs 4.83kg，＜0.01）、母豬失重顯著增加（-1.8kg vs 16.6kg，＜0.01）、泌乳量降低約30%（＜0.01）WILLIAMS等[24]研究發(fā)現(xiàn)，與適宜溫度環(huán)境相比（18—20℃），高溫環(huán)境（24—30℃）下的哺乳仔豬斷奶重顯著降低了0.5kg（＜0.05）；PRUNIER等[25]報道，與適宜環(huán)境溫度（18℃）相比，高溫環(huán)境（27℃）顯著提高了6—21日齡哺乳仔豬的死亡數(shù)（0.2頭 vs 0.7頭，＜0.05），極顯著降低母豬哺乳期采食量（6.10kg vs 4.40kg，＜0.001）和仔豬斷奶重（6.44kg vs 5.09kg，＜0.001）；SURIYASOMBOON等[26]的研究也證實了斷奶前期、配種期和分娩時環(huán)境高溫高濕會對仔豬產(chǎn)生不利影響。林映才等[27]總結(jié)了大量國外高溫環(huán)境對母豬及仔豬的影響，發(fā)現(xiàn)與適溫條件相比（18—22℃），熱應激（28—32℃）可使泌乳母豬采食量降低40%，泌乳量減少25%，仔豬增重減少20%，體重損失增加2.6倍。

斷奶至發(fā)情間隔直接影響母豬生產(chǎn)周期及年生產(chǎn)力[28]，熱應激通過影響母豬的采食量、泌乳期母豬失重和體內(nèi)生殖激素的分泌，進而導致母豬斷奶后發(fā)情延遲。研究指出，有9%的分娩母豬在夏季高溫時出現(xiàn)發(fā)情延遲現(xiàn)象[29]，且配種率下降，當豬舍環(huán)境溫度高于23℃時，母豬配種率極顯著降低（=0.001）[30]。PRUNIER等[25]研究發(fā)現(xiàn)，與適宜環(huán)境溫度（18℃）相比，高溫（27℃）導致母豬斷奶后10 d內(nèi)的發(fā)情率顯著降低（13/17 vs 7/18，＜0.05）。BOMA等[31]研究表明，隨著環(huán)境溫度的升高，母豬斷奶至發(fā)情間隔的時間逐漸增加，當平均溫度在37.2℃時發(fā)情間隔顯著高于25.6℃時的發(fā)情間隔（12.7 d vs 7.9 d）。高溫環(huán)境下，母豬斷奶至發(fā)情間隔增加，發(fā)情延遲則母豬空懷期延長，且生產(chǎn)者無法預測或保持仔豬輸出量，影響豬場生產(chǎn)力和經(jīng)濟效益[32-33]，因此，有必要在夏季高溫時采取措施緩解母豬熱應激。

1.2 行為及福利

行為是評價動物適應環(huán)境變化的重要指標。熱應激時母豬熱舒適性較差，會出現(xiàn)哺乳、躺臥姿勢、采食等行為變化，降低其福利水平，增加仔豬的壓死率[34-35]。高溫環(huán)境下，母豬會通過行為姿勢改變進行熱調(diào)節(jié)，如減少站立時間、增加側(cè)臥時間、減少俯臥時間等，側(cè)臥時母豬體表與地面的接觸面積更大，增加了機體傳導散熱量。MUNS等[36]從分娩前16h至分娩后24h連續(xù)測定了母豬的行為，發(fā)現(xiàn)兩組母豬（20℃和25℃）躺臥、坐和站立行為無顯著差異（＞0.05），但躺臥的姿勢存在顯著差異，與對照組（20℃）相比，熱應激環(huán)境（25℃）顯著提高母豬分娩前16h（47.3% vs 61.5%，=0.003）和分娩后24h（81.6% vs 92.6%，=0.018）側(cè)臥姿勢的時間，顯著降低母豬分娩前16h（61.3% vs 25.2%，=0.001）和分娩后24h（11.1% vs 3.9%，=0.038）俯臥姿勢的時間。高婭俊等[35]研究了高溫（30.4℃）和低溫（15.3℃）對分娩母豬行為的影響，發(fā)現(xiàn)低溫組均顯著提高母豬站立（10% vs 21.7%）、跪立（0.2% vs 0.4%）、腹臥（14% vs 25%）和臀部下落時間（3.4s vs 4.0s），降低側(cè)臥時間（66.9% vs 42.1%）以及母豬6 h內(nèi)的坐立-腹臥（4.7 vs 2.2）、腹臥-坐立（4.9 vs 2.5）的轉(zhuǎn)換頻次。由于母豬的坐立-腹臥、站立-躺臥行為的轉(zhuǎn)換以及臀部快速下落常常導致仔豬的壓死，高溫導致仔豬的壓死率顯著升高（15.2% vs 0），CANADAY等[37]的研究結(jié)果與其一致。DEVILLERS和FARMER[34]研究了環(huán)境溫度對分娩母豬行為的影響，發(fā)現(xiàn)與適溫環(huán)境（21℃）相比，高溫（29℃）顯著減少哺乳母豬的站立時間（11.4% vs 9.3%，=0.008），縮短哺乳時長（6.2 min vs 5.4min，=0.01），提高哺乳頻率（34.4 vs 37.5，＜0.001），這可能是由于高溫環(huán)境下母豬產(chǎn)奶量下降，仔豬由于饑餓而刺激母豬的哺乳行為。QUINIOU等[38]研究發(fā)現(xiàn)高溫環(huán)境下（29℃）泌乳母豬的采食次數(shù)（4.8 vs 7.3）、采食量（3 495g vs 6 423g）、采食時間（29.6min·d-1vs 50.4min·d-1）均比25℃環(huán)境顯著降低，而飲水量顯著提高（7.1l/kg采食量 vs 4.4l/kg采食量），并且高溫環(huán)境顯著降低夜間采食比例（10% vs 23%）。

1.3 生理狀況

母豬自身的體熱調(diào)控能力差，當其處于熱應激狀態(tài)時，會通過減少采食量、增加呼吸率和皮膚血流量等途徑來減少代謝產(chǎn)熱、增加散熱以適應高溫環(huán)境，但當其直腸溫度升高時，上述熱調(diào)控方式就不能完全補償熱應激帶來的不利影響，導致長時間的能量負平衡和母豬機體受損[39]。熱應激環(huán)境對初產(chǎn)母豬的生理狀況影響更為明顯，泌乳期的熱應激導致初產(chǎn)母豬的直腸溫度顯著高于經(jīng)產(chǎn)母豬（39.0℃ vs 38.7℃，＜0.019），這表明高溫降低初產(chǎn)母豬能量穩(wěn)衡的能力，并可能降低代謝能轉(zhuǎn)化為母乳的能力[40-41]。熱環(huán)境下，母豬體熱調(diào)節(jié)平衡被破壞，交感神經(jīng)興奮，顯著增加豬只呼吸量，使得呼吸頻率增加和深度變淺，呼吸頻率可超過40次/min[41-42]，DE OLIVEIRA等[43]報道，與21.0℃相比，25.7℃環(huán)境中分娩母豬的呼吸頻率顯著提高（早上：28.0次/min vs 43.7次/min；下午：33.7次/min vs 61.7次/min），但直腸溫度無顯著差異。WILLIAMS等[24]報道，分娩欄中處于熱應激環(huán)境（24—30℃）中的母豬，其直腸溫度顯著高于（＜0.001）適溫環(huán)境（18—20℃）中的母豬；熱應激環(huán)境中母豬的呼吸頻率約是適溫環(huán)境中母豬的2倍。MUNS等[36]的研究發(fā)現(xiàn)，與適溫環(huán)境（20℃）相比，高溫環(huán)境（25℃）顯著提高了母豬產(chǎn)前1 d (=0.033)和分娩當天（=0.004）的呼吸頻率；提高了分娩前1d到分娩后8d的直腸溫度，并且分娩后1d達到顯著水平；分娩3d內(nèi)的平均乳腺表面溫度提高了0.9℃。

腎上腺和甲狀腺在維持機體代謝、調(diào)節(jié)機體穩(wěn)態(tài)中起著重要作用，高溫環(huán)境可以改變母豬體內(nèi)激素水平[44]。熱應激時，母豬機體通過增加下丘腦促腎上腺皮質(zhì)激素釋放激素，促進促腎上腺皮質(zhì)激素分泌來對抗熱應激，而促腎上腺皮質(zhì)激素的分泌會抑制促卵泡素和促黃體素的分泌，導致母豬黃體、孕酮不足，出現(xiàn)胚胎早期死亡及流產(chǎn)[45]。MALMKVOST等[46]在母豬產(chǎn)前12h至產(chǎn)后48h給予地板加熱處理（33—34℃）發(fā)現(xiàn)，與對照組相比，地板加熱處理組母豬的皮質(zhì)醇和促腎上腺皮質(zhì)激素分別提高了29%(=0.02)和17%(=0.08)。BARB等[47]研究發(fā)現(xiàn)，與22℃飼養(yǎng)環(huán)境相比，30℃下母豬的甲狀腺素水平下降30%，黃體化激素水平不變，但其脈沖頻率（＜0.003）和振幅（＜0.03）均顯著提高。PRUNIER等[25]的研究結(jié)果顯示，與20℃相比，30℃熱應激環(huán)境顯著降低母豬血清三碘甲狀腺氨酸濃度（＜0.05），提高血糖濃度（＜0.001）。熱應激時豬只胰島素的敏感性增加，免疫系統(tǒng)是潛在的葡萄糖利用者，且免疫系統(tǒng)一旦激活，免疫細胞就會變成葡萄糖利用者，并改變了機體的能量穩(wěn)衡，因此需要更多的葡萄糖來維持血糖平衡，而與泌乳相關(guān)的葡萄糖利用率較低，這也在一定程度上解釋了高溫引起的泌乳量下降[22, 48-50]。

2 母豬溫熱環(huán)境調(diào)控技術(shù)

緩解母豬高溫熱應激是一項系統(tǒng)工作，除了通過豬舍設計與環(huán)境建設、合理的飼養(yǎng)管理技術(shù)、適宜的保健預防等[51-55]基礎措施以外，亦可配合蒸發(fā)冷卻降溫、水冷覆蓋降溫、地板降溫等舍內(nèi)溫度調(diào)控技術(shù)，使高溫環(huán)境對母豬生產(chǎn)繁殖性能產(chǎn)生的不利影響最小化。

2.1 豬舍整體降溫技術(shù)

豬舍整體降溫通常采用通風降溫、蒸發(fā)降溫兩種方式。通風降溫分為自然通風和機械通風，自然通風受氣候環(huán)境影響顯著，在炎熱潮濕的南方地區(qū)，其降溫效率受到限制；機械通風常應用于大型密閉性養(yǎng)豬場，以負壓通風為主，但存在通風死角或局部溫度過高的區(qū)域[56]。蒸發(fā)降溫包括濕簾風機降溫、噴淋降溫、噴霧降溫等，濕簾風機降溫系統(tǒng)由于其設備構(gòu)造簡單、降溫速度快、穩(wěn)定耐用等優(yōu)勢，目前廣泛應用于我國大部分密閉式豬舍[57-60]。

濕簾-風機降溫系統(tǒng)由特種紙質(zhì)多孔濕簾、低壓大流量軸流風機、水循環(huán)系統(tǒng)及控制裝置組成，濕簾、風機分別安裝在畜禽舍的兩端，風機抽風時造成舍內(nèi)負壓，迫使舍外未飽和的空氣流經(jīng)濕潤的多孔濕簾，引起水分蒸發(fā)吸收大量潛熱，降低進入舍內(nèi)的空氣溫度，從而達到降低舍內(nèi)溫度的目的。豬由于汗腺不發(fā)達，對高溫環(huán)境更為敏感[61-62]。濕簾-風機蒸發(fā)冷卻系統(tǒng)可改善暴露于極端熱環(huán)境中母豬的熱舒適性，緩解熱應激。DONG等[63]對比了縱向通風、頭部垂直通風、水平通風、滴水降溫等不同降溫組合在分娩母豬舍的應用效果，結(jié)果發(fā)現(xiàn)縱向通風配合滴水降溫是更為有效的降溫組合。高增月等[64]就濕簾-風機系統(tǒng)降溫和自然通風降溫的分娩舍進行了對比試驗，結(jié)果發(fā)現(xiàn)，夏季濕簾風機系統(tǒng)能顯著降低舍內(nèi)溫度（27.9℃vs 31.5℃，＜0.05），使哺乳仔豬的斷奶成活率提高6.97%。CARLAR等[65]研究了濕簾-風機系統(tǒng)妊娠舍舍內(nèi)母豬的生產(chǎn)性能及舍內(nèi)溫濕指數(shù)，與無降溫系統(tǒng)相比，濕簾-風機系統(tǒng)顯著降低母豬斷奶至發(fā)情間隔時間（5.29d vs 4.53d，＜0.05），顯著提高斷奶時母豬背膘厚（15.55mm vs 17.86mm，＜0.05），顯著提高了仔豬初生重（＜0.05），這與Liao等[66]的觀點一致；試驗期間有降溫系統(tǒng)的豬舍舍內(nèi)溫濕指數(shù)平均值（77.52）顯著低于（＜0.05）無降溫系統(tǒng)豬舍（79.67）。該結(jié)果與BLOEMHOF等[67]的研究結(jié)果一致，表明濕簾-風機降溫系統(tǒng)可顯著改善舍內(nèi)溫熱環(huán)境和提高母豬后續(xù)的生產(chǎn)性能。KIEFER等[68-69]使用CFD方法對分娩母豬舍濕簾降溫系統(tǒng)進行評估，指出該系統(tǒng)在風速、溫度和相對濕度等指標的均勻性方面需要進一步優(yōu)化。

2.2 豬舍局部降溫技術(shù)

豬舍局部降溫主要是針對豬只躺臥區(qū)地板、兩側(cè)豬欄、豬欄上方等區(qū)域進行溫度調(diào)控。局部降溫適用于開放舍和有通風死角的密閉舍，局部小環(huán)境溫度調(diào)控方法設備簡單、節(jié)能高效、氣流容易組織、溫控易于實現(xiàn)[18]。常用的豬舍局部降溫技術(shù)有冷水覆蓋地板或豬欄、噴氣嘴冷卻降溫等。

2.2.1 風管噴氣嘴蒸發(fā)冷卻系統(tǒng) 通過組織氣流，增加動物活動區(qū)風速，是緩解豬只熱應激的有效手段之一[70-71]，風管噴氣嘴蒸發(fā)冷卻系統(tǒng)即利用這一方式對豬舍局部降溫，以達到緩解母豬熱應激的目的。該系統(tǒng)由風管、濕墊、風機及控制系統(tǒng)組成。分娩豬舍一端外墻安裝連接著主風管的蒸發(fā)冷卻墊，經(jīng)過濕墊的冷空氣由軸流風機送入主風管進入舍內(nèi)，主風管由兩個獨立的支風管組成，每個支管服務兩排分娩欄，每個分娩欄上方有獨立的末端噴氣嘴使空氣到達豬脖頸區(qū)域，推薦流量為120m3·h-1[72]，當舍內(nèi)溫度高于20℃時系統(tǒng)自動開啟[73]。

PERIN等[73]人研究了傳統(tǒng)濕簾溫度控制系統(tǒng)（TTCS）和風管噴氣嘴蒸發(fā)冷卻系統(tǒng)（ESCS）對泌乳母豬直腸溫度、采食量、失重及其仔豬體重的影響。結(jié)果顯示，與TTCS組相比，ESCS組母豬直腸溫度顯著降低（＜0.05），失重顯著下降（5.3% vs 2.2%，＜0.05），斷奶至發(fā)情間隔顯著縮短（10.9 d vs 7.0 d，＜0.05），采食量顯著增加（4.8 kg·d-1vs 5.8 kg·d-1，＜0.05），窩產(chǎn)仔數(shù)顯著增加（10.9頭vs 12.0頭，=0.095），采食量的變化與RENAUDEAU等[74]的研究結(jié)果一致，溫度通過影響母豬體重間接影響其斷奶至發(fā)情間隔[75]。JUSTINO等[76]比較了傳統(tǒng)機械通風與風管蒸發(fā)冷卻系統(tǒng)在分娩母豬上的降溫效果，結(jié)果發(fā)現(xiàn)，與傳統(tǒng)機械通風降溫相比，風管蒸發(fā)冷卻降溫可使母豬頭部上方區(qū)域干球溫度降低2.09℃（＜0.05），母豬體表溫度降低0.47℃（＜0.05），呼吸頻率降低25.4%（＜0.05）。相比于傳統(tǒng)溫度控制系統(tǒng)，風管蒸發(fā)冷卻系統(tǒng)的使用對于增加母豬熱損耗作用顯著，能緩解高溫對母豬體溫調(diào)節(jié)的負面影響，使母豬采食量顯著提高、體重損失減少、繁殖性能提高，母豬和仔豬生產(chǎn)性能均明顯改善。

2.2.2 冷水覆蓋降溫 冷水覆蓋降溫是在豬欄上方及側(cè)面鋪設冷水管，通過熱傳導及輻射作用，使豬欄相鄰單元達到適宜的溫度環(huán)境。PANG等[77-78]研發(fā)了一套冷水覆蓋降溫系統(tǒng)（WCCs），并探究了該系統(tǒng)對高溫高濕氣候下分娩母豬生理和生產(chǎn)性能參數(shù)的影響。WCCs由鋼結(jié)構(gòu)框架、鍍鋅鋼制水管和鋁制遮蓬組成，水管沿長度方向安裝于拱形頂內(nèi)側(cè)，兩端為2根豎直水管（其中相鄰單元間共用1根豎直管），3單元為一組，進出水口分別位于該組WCC兩側(cè)，拱頂上部覆蓋聚乙烯泡沫隔熱。研究結(jié)果顯示，當舍內(nèi)環(huán)境溫度為37℃時，系統(tǒng)可以將母豬躺臥區(qū)溫度降低3.0—4.5℃，在舍內(nèi)溫度小于35℃時保持適宜的溫度范圍（25—30℃）；當環(huán)境溫度低于30℃時，分娩母豬的呼吸頻率和體表溫度在處理組（WCCs）和對照組（灑水冷卻）之間無顯著差異，但當溫度升高到30℃以上時差異顯著（＜0.05）；對照組母豬在炎熱天氣時飲水量較多，但采食量顯著少于處理組的母豬（＜0.01）。室內(nèi)空氣溫度為34.3℃時，在WCCs的作用下，母豬躺臥區(qū)的黑球溫度在有母豬和無母豬的情況下分別可降溫4.8℃和5.4℃；母豬躺臥區(qū)的溫降幅度與系統(tǒng)進出水溫度差成正比，在一定范圍內(nèi)增加水流速度可提高降溫效率[79]。李偉等[80]研究了冷水覆蓋降溫對母豬躺臥行為的影響，結(jié)果發(fā)現(xiàn)，當豬舍溫度大于31℃時，75%的母豬選擇在冷水覆蓋豬床內(nèi)躺臥，且該比例隨著環(huán)境溫度升高而增加。因此，水冷覆蓋降溫系統(tǒng)的使用可以減輕典型炎熱氣候期間分娩母豬的熱應激，具有提高母豬生產(chǎn)性能的實用價值。

2.2.3 豬舍地板局部降溫 豬舍地板局部降溫是指以地下水或壓縮冷卻水為媒介、在豬的躺臥區(qū)地板下部鋪設水管的一種傳導降溫方式。據(jù)報道，豬只一天中有79%的時間（約19 h）都在休息，這意味著大部分豬只的身體長時間與地面接觸[81]，因此，高溫季節(jié)采取地板降溫是一種有效緩解豬只熱應激的方式。李保明[82]等研發(fā)了一種利用地下水對豬舍地板局部降溫的技術(shù)，試驗發(fā)現(xiàn)環(huán)境溫度34℃時該技術(shù)可將母豬躺臥區(qū)域溫度控制在22—26℃，與SHI等的結(jié)果一致[83]。BARBARI等[84]發(fā)現(xiàn)在高溫季節(jié)母豬同時使用地板降溫和氣流降溫更為舒適。SILVA等[85-86]研究發(fā)現(xiàn)，采用地板降溫（地板溫度27.6℃）母豬的采食量（6.47kg·d-1vs 5.61kg·d-1，＜0.01）、斷奶時仔豬體重（6.42kg/頭 vs 5.30 kg/頭）顯著高于對照組（地板溫度35.8℃）；地板降溫組母豬的直腸溫度、體表溫度和呼吸率均更低（＜0.01），側(cè)臥時間更短（＜0.01）、哺乳時間更長（＜0.05）、采食時間更長（＜0.01）。CABEZON等[87-88]初步評估了降溫地板的3種水流速度（0.25、0.55和0.85 L·min-1）對高溫環(huán)境下（環(huán)境溫度35.3℃，相對濕度57.8%）分娩母豬的影響，高水流速度（0.85 L·min-1）時，分娩母豬各項指標最佳（呼吸率為31，直腸溫度為39.1℃，散熱率為320.7w）。地板降溫方式可增加哺乳母豬的日采食量，減少失重，縮短斷奶至發(fā)情間隔，同時可改善母豬哺乳行為，增加泌乳量。

3 結(jié)語

母豬作為生豬養(yǎng)殖場的核心豬群，適宜溫熱環(huán)境的控制至關(guān)重要，這有利于保障母豬健康狀況，從而提高其生產(chǎn)和繁殖性能。蒸發(fā)冷卻降溫、水冷覆蓋降溫、地板降溫等溫熱環(huán)境調(diào)控技術(shù)，在實際生產(chǎn)中，除了濕簾-風機蒸發(fā)降溫系統(tǒng)在規(guī)模豬場中利用率較高，其余幾種技術(shù)雖然降溫效果明顯、運行能耗低，但受成本、管理等因素限制，尚未被推廣應用，還有待進一步結(jié)合實際進行優(yōu)化應用。本文所述母豬溫熱環(huán)境調(diào)控技術(shù)僅為該領(lǐng)域內(nèi)典型部分，以期為我國生豬養(yǎng)殖場母豬溫熱環(huán)境調(diào)控實施提供參考。

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（責任編輯 林鑒非）

Effects of Ambient Temperature on Production Performance of Sows and Regulatory Techniques

ZENG YaQiong1, WANG Hao1,2, LIU ZuoHua1, LI Shuang1, PU ShiHua1,2, LONG DingBiao1,2

(1;2Ministry of Agriculture Southwest facility aquaculture engineering scientific observation experimental station, Chongqing 402460)

The pig industry is one of the mainstay industries of China's agriculture and rural economy. As the core component of pig farms, production performance of sows are the key factors for determining the economic benefits of pig farms. China is the largest pig breeding country in the world, and the number of breeding sows and commercial pigs are more than 50% of the world’s total. However, compared with developed countries, sows feeding management level is low in our country, and there is still a large gap in production performance. The performance of sows in practical production is affected by many factors, including nutrient intake, body characteristics, feeding environment, parity of sows, etc. Thermal environment is one of the major factors affecting the health and production performance of sows. The warm environment consists of temperature, relative humidity, air flow, radiation, and heat transfer. These factors work together on the animal to make them feel cold or hot and comfortable or not. The suitable thermal environment is conducive to ensuring the sows’ health and improving their production performance. Conversely, the unsuitable warm environment will cause heat stress in sows, destroy the body heat balance, and even lead production stop, make the body enters a pathological state, cause illness and ultimately death. Therefore, mastering the warm environment requirements of sows and adopting effective control measures are essential to improve the performance of sows and the economic benefits of pig farms.This paper reviewed the effects of warm environment on sows and the corresponding regulation techniques, aiming to provide theoretical basis and technical support for the regulation of thermal environment in pig production and management in China. (1) The effects of the warm environment on the sow are mainly reflected in changes of behavior, physiology and production performance. In terms of behavior, sows will be thermally adjusted by changing the behavioral posture, such as increasing the lying time, reducing the standing and prone time in hot environment. Because the contact area of the sows' body surface with the ground is larger when the side is lying, and the heat dissipation of the body can be increased, but frequent changes in sows’ posture will increase the piglet death rate. In the aspect of physiology, sows will reduce metabolic heat production and increase heat dissipation by reducing feed intake, increasing respiration rate and skin blood flow during heat stress, while promoting the adrenocorticotropic hormone and cortisol in the blood of sows, thyroxine dropped and insulin sensitivity increased. These physiological changes will destroy the endocrine and energy balance of the sow, leading to early embryo death, miscarriage and milk production reduction. In terms of production performance, heat stress adversely affects the performance of sow estrus interval, litter size and lactation. Heat stress mainly affects the re-service rate and litter size at pre-pregnancy and in late pregnancy mainly affects the number of live births and stillbirths. After parturition, heat stress mainly affects the survival rate of piglets. High ambient temperature adversely affects the performance of weaned piglets by affecting the lactation of sows, and heat stress can delay the weaning-to-estrus interval by affecting the feed intake, weight loss and hormone secretion of sows. (2) Thermal environment control technology of sows mainly includes overall cooling and partial cooling of the pig house. The Pad and Fan evaporative cooling system is the representative of the overall cooling of pig house. In the system, the negative pressure inside the house is caused by the exhaust of the fan, forcing the unsaturated air outside the house to flow through the wet porous curtain, causing the evaporation of water to absorb a large amount of latent heat, thereby reducing the temperature inside pig house. The system has the advantages of simplicity and cost-effectiveness. The local cooling of the pig house is mainly for the temperature control of the lying area floor, pig pens on both sides and upper part of the pig pens. The main methods include air duct evaporative cooling, cold water cover cooling, floor cooling, etc. These methods have the advantages of obvious cooling effect and energy saving.

sows; ambient temperature; regulation; performance

2018-04-10；

2018-07-17

“十三五”國家重點研發(fā)計劃（2016YFD0500500）、現(xiàn)代農(nóng)業(yè)產(chǎn)業(yè)技術(shù)體系建設專項資金（CARS-35）、重慶市科研院所績效激勵引導專項（17422）

曾雅瓊，E-mail：zengyaqionghai@163.com。

蒲施樺，E-mail：opertion5@163.com。通信作者龍定彪，E-mail：longjuan880@163.com