不同飼料效率與綿羊瘤胃組織形態(tài)學(xué)關(guān)系

張德印，張小雪，李發(fā)弟,2，李沖,2，李國(guó)澤，張煜坤，李曉龍，宋其志，趙源，劉曉青，馬亮強(qiáng)，王維民

不同飼料效率與綿羊瘤胃組織形態(tài)學(xué)關(guān)系

張德印1，張小雪1，李發(fā)弟1,2，李沖1,2，李國(guó)澤1，張煜坤1，李曉龍1，宋其志1，趙源1，劉曉青1，馬亮強(qiáng)1，王維民1

（1甘肅農(nóng)業(yè)大學(xué)動(dòng)物科學(xué)技術(shù)學(xué)院，蘭州 730030；2甘肅省肉羊繁育生物技術(shù)工程實(shí)驗(yàn)室，甘肅民勤 733300）

【】利用單欄系統(tǒng)測(cè)定個(gè)體的飼料效率相關(guān)性狀與瘤胃組織形態(tài)學(xué)指標(biāo)，探討綿羊飼料效率與瘤胃組織形態(tài)的關(guān)系，為解析綿羊飼料效率性狀的影響因素研究提供基礎(chǔ)數(shù)據(jù)。隨機(jī)選取出生日齡相近、系譜信息詳細(xì)、健康狀況良好的187湖羊公羔，56 d斷奶后轉(zhuǎn)入單欄飼養(yǎng)，過(guò)渡期14 d，預(yù)飼期10 d，正試期100 d。正試期內(nèi)所有羊只僅飼喂顆粒飼料，自由采食及飲水，并在80 d和180 d晨飼前空腹測(cè)定其體重（body weight，BW）和80—180 d間的采食量（feed intake，F(xiàn)I），計(jì)算平均日增重（average daily gain，ADG）、中期代謝體重（metabolic body weight, MBW）、飼料轉(zhuǎn)化率（feed conversion rate，F(xiàn)CR）和剩余采食量（residual feed intake，RFI）等飼料效率相關(guān)性狀并對(duì)其進(jìn)行描述性統(tǒng)計(jì)，于180 d飼養(yǎng)結(jié)束后屠宰采集瘤胃腹囊組織1 cm2保存于4%甲醛溶液中，用于制作組織切片并觀測(cè)其瘤胃乳頭長(zhǎng)度、寬度和肌層厚度。最后將其與飼料效率相關(guān)性狀進(jìn)行相關(guān)分析和方差分析。飼料效率相關(guān)性狀的變異系數(shù)均大于10%，且剩余采食量最大與最小的個(gè)體每天的剩余采食量之差達(dá)0.57 kg。飼料效率相關(guān)性狀間的表型相關(guān)分析表明剩余采食量與飼料轉(zhuǎn)化率（r= 0.68）和采食量（r= 0.48）呈極顯著正相關(guān)（＜0.01），與初始體重（r=0）、末期體重（r= -0.01）和平均日增重（r= -0.02）無(wú)顯著相關(guān)（＞0.05）。飼料效率相關(guān)性狀與瘤胃組織形態(tài)相關(guān)性分析發(fā)現(xiàn)，瘤胃乳頭長(zhǎng)度與平均日增重、采食量、初始體重和末期體重呈顯著或極顯著正相關(guān)（＜0.05或＜0.01），肌層厚度與平均日增重、采食量和末期體重呈顯著或極顯著正相關(guān)（＜0.05或＜0.01），而剩余采食量和飼料轉(zhuǎn)化率與瘤胃組織形態(tài)無(wú)顯著相關(guān)。不同RFI組羔羊采食量、飼料轉(zhuǎn)化率和瘤胃肌層厚度存在顯著或極顯著差異（0.05或＜0.01），瘤胃乳頭長(zhǎng)、寬無(wú)顯著差異（＞0.05），其中High-RFI組羔羊采食量和飼料轉(zhuǎn)化率極顯著高于Low-RFI組（＜0.01），肌層厚度顯著高于Medium-RFI組（＜0.05）；不同F(xiàn)CR組羔羊的剩余采食量、采食量、ADG、初始體重、末期體重和乳頭長(zhǎng)度存在顯著或極顯著差異（＜0.05或＜0.01），肌層厚度和乳頭寬度差異不顯著（＞0.05），其中High-FCR組羔羊剩余采食量、采食量、ADG、初始體重和末期體重均顯著或極顯著高于Low-FCR組（＜0.05或＜0.01），Medium-FCR組羔羊乳頭長(zhǎng)度顯著長(zhǎng)于Low-FCR組（＜0.05）；除瘤胃乳頭寬度外，不同F(xiàn)I組羔羊的上述指標(biāo)均存在顯著或極顯著差異（＜0.05或＜0.01），且High-FI組羔羊的剩余采食量、飼料轉(zhuǎn)化率、ADG、初始體重、末期體重、肌層厚度和乳頭長(zhǎng)度均顯著或極顯著高于Low-FI組（＜0.05或＜0.01）；不同ADG組羔羊采食量、飼料轉(zhuǎn)化率、初始體重、末期體重和肌層厚度均存在顯著或極顯著差異（＜0.05或＜0.01），乳頭長(zhǎng)度和乳頭寬度無(wú)顯著差異（＞0.05），其中High-ADG組羔羊采食量、剩余采食量、初始體重、末期體重和肌層厚度均顯著或極顯著高于Low-ADG組，飼料轉(zhuǎn)化率則極顯著低于Low-ADG組。剩余采食量與采食量和飼料轉(zhuǎn)化率等飼料效率性狀呈極顯著正相關(guān)，表明其可作為衡量飼料效率的潛在指標(biāo)。剩余采食量和飼料轉(zhuǎn)化率與瘤胃組織形態(tài)學(xué)指標(biāo)無(wú)顯著相關(guān)，采食量和平均日增重與瘤胃乳頭長(zhǎng)度和肌層厚度呈顯著正相關(guān)，表明羔羊瘤胃組織形態(tài)對(duì)采食量和增重有顯著影響，但其進(jìn)一步的作用機(jī)制有待深入研究。

剩余采食量；飼料轉(zhuǎn)化率；瘤胃；組織形態(tài)；湖羊

0 引言

【研究意義】在肉羊生產(chǎn)實(shí)踐中，飼草料成本約占總成本的65%—70%，因此提高飼料效率對(duì)經(jīng)濟(jì)具有重要的意義。在畜禽生產(chǎn)中，飼料效率通常被定義為動(dòng)物將飼料轉(zhuǎn)化為產(chǎn)品的相對(duì)能力，目前飼料轉(zhuǎn)化率（feed conversion rate，F(xiàn)CR）和剩余采食量（residual feed intake，RFI）作為衡量飼料效率最常用的指標(biāo)[1-3]，但剩余采食量仍處于探討與研究的階段，因此需要更進(jìn)一步地評(píng)價(jià)其作為衡量飼料效率指標(biāo)的科學(xué)性?！厩叭搜芯窟M(jìn)展】1963年，KOCH等[4]首次提出了剩余采食量（residual feed intake，RFI）作為估測(cè)畜禽飼料利用效率的指標(biāo)，是指畜禽實(shí)際采食量與預(yù)期的根據(jù)生產(chǎn)性能（體增重、產(chǎn)奶量和產(chǎn)蛋數(shù)等）需要和維持體重需要的標(biāo)準(zhǔn)而計(jì)算得出的采食量之差。RFI反映的是畜禽本身由遺傳背景決定的代謝差異而導(dǎo)致的飼料利用效率的差異[5]，其與畜禽的體型大小及生產(chǎn)性能，甚至是屠宰性能和肉品質(zhì)等性狀相互獨(dú)立，計(jì)算過(guò)程中既考慮了畜禽的體增重，也校正了其代謝體重。在對(duì)RFI進(jìn)行遺傳改良的同時(shí)，不會(huì)對(duì)生長(zhǎng)及生產(chǎn)性狀造成不良影響或影響很小[6-7]。因此，RFI可作為評(píng)價(jià)飼料效率的潛在育種指標(biāo)。目前有關(guān)RFI的研究主要集中在豬[8-9]、牛[10-11]和禽[12-13]上，有關(guān)綿羊RFI的研究較少?！颈狙芯壳腥朦c(diǎn)】瘤胃是反芻動(dòng)物特有的消化器官[14]，瘤胃乳頭高和乳頭寬等形態(tài)學(xué)結(jié)構(gòu)，決定了瘤胃上皮對(duì)養(yǎng)分吸收和離子的轉(zhuǎn)運(yùn)能力[15]。而養(yǎng)分吸收和利用的效率決定動(dòng)物飼料效率的高低。目前有關(guān)瘤胃形態(tài)學(xué)的研究主要集中在不同生長(zhǎng)時(shí)期[16-18]、不同飼料類(lèi)型和結(jié)構(gòu)[19]、以及不同斷奶時(shí)間[20]對(duì)瘤胃發(fā)育的影響，但不同飼料效率羔羊瘤胃組織形態(tài)與飼料效率的關(guān)系的研究報(bào)道較少?！緮M解決的關(guān)鍵問(wèn)題】本研究以湖羊公羔為研究對(duì)象，利用單欄系統(tǒng)測(cè)定個(gè)體的采食量、剩余采食量、飼料轉(zhuǎn)化率、平均日增重（average daily gain，ADG）等飼料效率相關(guān)的性狀，并觀測(cè)瘤胃組織形態(tài)學(xué)指標(biāo)，探討綿羊飼料效率與瘤胃組織形態(tài)的關(guān)系，為解析綿羊飼料效率性狀的影響因素研究提供基礎(chǔ)數(shù)據(jù)。

1 材料與方法

1.1 試驗(yàn)群體與飼養(yǎng)管理

試驗(yàn)于2018年5—9月在甘肅民勤勤鋒灘進(jìn)行，所有試驗(yàn)羊只是從金昌中天羊業(yè)有限公司（甘肅，金昌）隨機(jī)選取187只系譜信息詳細(xì)、出生日期相近、身體健康、發(fā)育狀態(tài)良好的湖羊公羔，56 d斷奶后轉(zhuǎn)于民勤縣德福農(nóng)業(yè)科技有限公司（甘肅，民勤）進(jìn)行單欄飼養(yǎng)，每個(gè)欄位裝有獨(dú)立的水槽和料槽，在進(jìn)行試驗(yàn)前按羊場(chǎng)常規(guī)程序?qū)ρ蛑贿M(jìn)行免疫和驅(qū)蟲(chóng)，根據(jù)羊場(chǎng)飼喂方式，每天飼喂4次，試驗(yàn)羊只自由采食和飲水，并對(duì)羊舍每14 d進(jìn)行一次消毒。試驗(yàn)期包括57—70 d的過(guò)渡期14 d，在過(guò)渡期間每天增加7.1%的全價(jià)顆粒飼料以代替羔羊料；71—80 d的預(yù)飼期，10 d；81—180 d的正試期，在正試期所有羊只均飼喂全價(jià)顆粒料。分別測(cè)定80—180 d期間的采食量、80 d和180 d體重，體重在晨飼前空腹測(cè)定。飼養(yǎng)試驗(yàn)結(jié)束后，立即屠宰采集瘤胃腹囊組織1 cm2保存于4%甲醛溶液中，用于后續(xù)制作組織切片。

1.2 試驗(yàn)方法

1.2.1 剩余采食量（residual feed intake，RFI）的計(jì)算 本試驗(yàn)的預(yù)測(cè)采食量是通過(guò)試驗(yàn)羊只的實(shí)際日采食量（AFI）與平均日增重（ADG）和平均中期代謝體重（MBW）多元回歸模型來(lái)計(jì)算，其中ADG和MBW被作為固定效應(yīng)，所用計(jì)算方法參照莫負(fù)濤[21]構(gòu)建的回歸模型：

ADG=(BW180-BW80)/N，MBW=[1/2×(BW180+ BW80)]0.75，Yi=β0+β1(ADGi)+β2(MBWi)+ei，F(xiàn)CR=FI/（BW180-BW80），其中，ADG為平均日增重，MBW為平均中期代謝體重（W0.75），BW80為試驗(yàn)初始體重，BW180為試驗(yàn)?zāi)┢隗w重，F(xiàn)I為采食量，N為飼養(yǎng)天數(shù)，Yi表示動(dòng)物i的實(shí)際干物質(zhì)采食量，β0表示回歸截距，β1為固定值，表示ADG對(duì)采食量的影響程度，β2表示MBW對(duì)采食量的影響程度，為定值。ei表示第i只動(dòng)物的隨機(jī)誤差，即RFI=實(shí)際采食量-預(yù)測(cè)采食量。

1.2.2 試驗(yàn)分組與統(tǒng)計(jì)分析 根據(jù)個(gè)體RFI對(duì)試驗(yàn)群體進(jìn)行排序，將試驗(yàn)群體按平均值和標(biāo)準(zhǔn)差分為High-RFI組（High＞0.05）、Medium-RFI組（-0.05≤Medium≤0.05）和Low-RFI組（Low＜-0.05）3組。

根據(jù)個(gè)體ADG對(duì)試驗(yàn)群體進(jìn)行排序，將試驗(yàn)群體按平均值和標(biāo)準(zhǔn)差分為High-ADG組（High＞0.29）、Medium-ADG組（0.26≤Medium≤0.29）和Low-ADG組（Low＜0.26）3組。

根據(jù)個(gè)體FI對(duì)試驗(yàn)群體進(jìn)行排序，將試驗(yàn)群體按平均值和標(biāo)準(zhǔn)差分為High-FI組（High＞165.82）、Medium-FI組（144.98≤Medium≤165.82）和Low-FI組（Low＜144.98）3組。

根據(jù)個(gè)體FCR對(duì)試驗(yàn)群體進(jìn)行排序，將試驗(yàn)群體按平均值和標(biāo)準(zhǔn)差分為High-FCR組（High＞6.06）、Medium-FCR組（5.48≤Medium≤6.06）和Low-FCR組（Low＜5.48）3組。

1.2.3 切片制作與數(shù)據(jù)測(cè)定 參考溫蕾等[22]的石蠟切片制作過(guò)程制作瘤胃組織切片。在進(jìn)行石蠟包埋、切片、蘇木精-伊紅染色后，選擇3—5張切片，每張選5個(gè)典型視野（組織完整），采用Image-Pro Express 6.0圖像分析系統(tǒng)軟件分別測(cè)量瘤胃腹囊乳頭長(zhǎng)度和寬度以及瘤胃肌層的厚度。

1.3 數(shù)據(jù)處理

利用SPSS 16.0軟件和R語(yǔ)言（版本3.6.1）對(duì)測(cè)得的數(shù)據(jù)進(jìn)行分析，結(jié)果用平均值±標(biāo)準(zhǔn)差表示，采用Tukey法進(jìn)行多重比較，統(tǒng)計(jì)結(jié)果以＜0.05為差異顯著，＜0.01為差異極顯著；對(duì)飼料效率相關(guān)性狀及其與瘤胃組織形態(tài)進(jìn)行皮爾遜相關(guān)性分析，并使用corrplot和pheatmap包作圖。

2 結(jié)果

2.1 飼料效率相關(guān)性狀描述性統(tǒng)計(jì)量

試驗(yàn)測(cè)定了試驗(yàn)羊只80—180 d期間的采食量和80 d體重和180 d體重，分別計(jì)算剩余采食量、飼料轉(zhuǎn)化率、平均日增重等相關(guān)性狀結(jié)果如表1所示。發(fā)現(xiàn)剩余采食量最高和最低個(gè)體每天的剩余采食量之差達(dá)0.57 kg，其次各性狀的變異系數(shù)均大于10%，且初始體重的變異系數(shù)最大。

2.2 飼料效率相關(guān)性狀的相關(guān)性分析

相關(guān)性分析結(jié)果表明剩余采食量與平均日增重、初始體重和末始體重?zé)o顯著相關(guān)，但與采食量（r=0.48）和飼料轉(zhuǎn)化率（r=0.68）呈極顯著正相關(guān)（＜0.01），而且采食量與平均日增重（r = 0.73）、初始體重（r = 0.87）和末期體重（r = 0.73）高度相關(guān)，與飼料轉(zhuǎn)化率（r = 0.45）呈中等相關(guān)（＜0.01）。飼料轉(zhuǎn)化率與平均日增重呈極顯著負(fù)相關(guān)（r=-0.28，＜0.01，圖1）。

2.3 羔羊瘤胃組織形態(tài)及其與飼料效率相關(guān)性狀的相關(guān)性分析

由圖2可知，不同飼料效率羔羊瘤胃的肌層厚度和乳頭長(zhǎng)度存在一定差異，并與飼料效率性狀關(guān)聯(lián)分析發(fā)現(xiàn)剩余采食量和飼料轉(zhuǎn)化率與瘤胃乳頭寬度、長(zhǎng)度以及肌層厚度的相關(guān)程度不高，但平均日增重、采食量和末期體重與瘤胃乳頭長(zhǎng)度和肌層厚度呈顯著正相關(guān)，而初始體重僅與乳頭長(zhǎng)度呈顯著正相關(guān)（圖3）。

2.4 不同剩余采食量羔羊瘤胃組織形態(tài)學(xué)

由表2可知，不同RFI組羔羊的平均日增重、初始體重、末期體重、乳頭長(zhǎng)度和乳頭寬度均無(wú)顯著差異（＞0.05），但采食量、飼料轉(zhuǎn)化率和瘤胃肌層厚度存在顯著或極顯著差異（＜0.05或＜0.01），其中High-RFI組羔羊的采食量、飼料轉(zhuǎn)化率極顯著高M(jìn)edium-RFI和Low-RFI組（＜0.01），并且High-RFI組羔羊瘤胃腹囊組織肌層厚度顯著高于Medium-RFI組羔羊（＜0.05），但與Low-RFI組羔羊無(wú)顯著差異（＞0.05）。

表1 飼料效率相關(guān)性狀的描述性統(tǒng)計(jì)

每個(gè)圓的大小表示相關(guān)系數(shù)的絕對(duì)值。藍(lán)色和紅色梯度分別表示正相關(guān)或負(fù)相關(guān)。**表示差異極顯著（P＜0.01），*表示差異顯著（P＜0.05）

a：低飼料效率組；b：中飼料效率組；c：高飼料效率組 a: Low feed efficiency group; b: Medium feed efficiency group; c: High feed efficiency group

2.5 不同日增重羔羊瘤胃組織形態(tài)學(xué)

由表3可知，在不同日增重組羔羊中，采食量、飼料轉(zhuǎn)化率、初始體重、末期體重和肌層厚度存在顯著差異（＜0.05），其他指標(biāo)在3組間均無(wú)顯著差異（＞0.05），High-ADG組羔羊的采食量和末期體重極顯著高于Medium-ADG和Low-ADG組（＜0.01）；High-ADG組羔羊的飼料轉(zhuǎn)化率極顯著低于Medium- ADG和Low-ADG組（＜0.01）；但High-ADG組羔羊瘤胃腹囊組織肌層厚度顯著高于Low-ADG組羔羊（＜0.05）。

藍(lán)色和紅色梯度分別表示正相關(guān)或負(fù)相關(guān)。**表示差異極顯著（P＜0.01），*表示差異顯著（P＜0.05）

表2 不同剩余采食量羔羊瘤胃組織形態(tài)

同列中數(shù)值標(biāo)注不同小寫(xiě)字母表示差異顯著（＜0.01）；不同大寫(xiě)字母表示差異極顯著（＜0.05）。下同

In the same column, different lowercase letters represent significant differences (＜0.05), different capital letters represent extremely significant differences (＜0.01). The same as below

表3 不同日增重羔羊瘤胃組織形態(tài)

2.6 不同采食量羔羊瘤胃組織形態(tài)學(xué)

由表4可知，與飼料效率相關(guān)的剩余采食量、飼料轉(zhuǎn)化率、平均日增重、初始體重和末期體重在不同采食量組中均存在極顯著差異（＜0.01），且High-FI組極顯著高于Medium-FI和Low-FI組。在不同采食量羔羊瘤胃組織形態(tài)學(xué)中，High-FI組羔羊瘤胃腹囊組織肌層厚度顯著高于Low-FI組羔羊（＜0.05），High-FI和Medium-FI組羔羊瘤胃腹囊組織乳頭長(zhǎng)度極顯著高于Low-FI組羔羊（＜0.01），但乳頭寬度無(wú)顯著差異（＞0.05）。

表4 不同采食量羔羊瘤胃組織形態(tài)

2.7 不同飼料轉(zhuǎn)化率羔羊瘤胃組織形態(tài)學(xué)

由表5可知，不同飼料轉(zhuǎn)化率組羔羊的剩余采食量、采食量、平均日增重、初始體重、末期體重以及瘤胃腹囊組織乳頭長(zhǎng)度存在顯著差異（＜0.05），肌層厚度和乳頭寬度無(wú)顯著差異（＞0.05）。其中，High- FCR組羔羊的RFI、FI、Initial BW極顯著高于Medium-和Low-FCR組羔羊（＜0.01）；Medium-和Low-FCR組羔羊的平均日增重極顯著高于High-FCR組（＜0.01）；并且Medium-FCR組羔羊的末期體重和瘤胃腹囊組織乳頭長(zhǎng)度顯著長(zhǎng)于Low-FCR組羔羊（＜0.05）。

表5 不同飼料轉(zhuǎn)化率羔羊瘤胃組織形態(tài)

3 討論

飼料效率是衡量飼料利用率的主要指標(biāo)，當(dāng)飼料效率較低時(shí)，會(huì)使飼養(yǎng)成本增加，因此提高飼料效率顯得尤為重要。并且瘤胃是反芻動(dòng)物特有的消化器官[23-24]，在動(dòng)物機(jī)體的消化代謝過(guò)程中具有極其重要的作用，是反芻動(dòng)物健康生長(zhǎng)的基礎(chǔ)。在瘤胃形態(tài)學(xué)研究中，瘤胃乳頭長(zhǎng)度是最重要的指標(biāo)，其次是瘤胃乳頭寬度和肌層厚度[25]。剩余采食量是一個(gè)具有中等遺傳力的負(fù)向選擇性狀，遺傳力為0.18—0.43[26-27]，是衡量飼料利用效率的一個(gè)重要指標(biāo)。有學(xué)者對(duì)畜禽剩余采食量的研究中，發(fā)現(xiàn)剩余采食量與采食量、消化率、體組織代謝、活動(dòng)量、體溫調(diào)節(jié)等生理因素有密切關(guān)系[28-29]。本研究對(duì)不同飼料效率羔羊瘤胃組織形態(tài)的研究結(jié)果顯示，按RFI值分組后，發(fā)現(xiàn)在同樣的飼喂條件下Low-RFI組羔羊的FI和FCR極顯著低于Medium-RFI和High-RFI組，且不同組間的生長(zhǎng)性能如ADG、初始體重、末期體重均無(wú)顯著差異，這與莫負(fù)濤[21]和MCGEE等[30]的研究結(jié)果相一致。其次發(fā)現(xiàn)High-RFI組羔羊瘤胃腹囊組織肌層厚度顯著高于Medium-RFI組羔羊，但瘤胃乳頭長(zhǎng)度和寬度在不同組間也無(wú)顯著差異這與梁玉生[31]的研究結(jié)果相一致。表明對(duì)RFI的選擇不會(huì)影響瘤胃乳頭的發(fā)育，進(jìn)而不會(huì)影響個(gè)體的生長(zhǎng)性能。此外，本研究按平均日增重(ADG)、采食量（FI）、飼料轉(zhuǎn)化率(FCR)等影響飼料效率的重要性狀對(duì)試驗(yàn)群體進(jìn)行分組，結(jié)果表明不同ADG羔羊的采食量、飼料轉(zhuǎn)化率、初始體重、末期體重、瘤胃肌層厚度存在顯著差異，其中High-ADG組羔羊的飼料轉(zhuǎn)化率極顯著低于Medium-ADG和Low-ADG組，但High-ADG組羔羊瘤胃肌層厚度顯著高于Low-ADG組羔羊，表明瘤胃肌層厚度可能會(huì)影響飼料效率。飼料相關(guān)性狀在不同F(xiàn)I組均存在極顯著差異，并且High-FI羔羊瘤胃肌層厚度和乳頭長(zhǎng)度均顯著高于Low-FI羔羊，可能與采食量的增多可提高瘤胃的運(yùn)動(dòng)水平，從而促進(jìn)瘤胃肌層厚度的發(fā)育有關(guān)，這與朱文濤等[32]等的研究表明飼料的物理刺激是影響瘤胃肌層發(fā)育的主要因素相符；不同F(xiàn)CR組羔羊瘤胃乳頭長(zhǎng)度以及飼料效率相關(guān)的性狀均存在顯著差異，其中Medium-FCR組羔羊瘤胃乳頭長(zhǎng)度顯著高于Low-FCR組羔羊，與High-FCR組無(wú)顯著差異，但Medium-和Low-FCR組羔羊的平均日增重極顯著高于High-FCR組；表明羔羊瘤胃組織形態(tài)的發(fā)育有利于提高飼料效率，特別是瘤胃乳頭長(zhǎng)度和肌層厚度，但其進(jìn)一步作用機(jī)理還有待深入研究。

4 結(jié)論

本研究結(jié)果表明剩余采食量與生長(zhǎng)性狀無(wú)顯著相關(guān)，與采食量和飼料轉(zhuǎn)化率呈顯著正相關(guān)，且Low-RFI組羔羊飼料轉(zhuǎn)化率極顯著低于High-RFI組，表明RFI可作為評(píng)價(jià)飼料效率的潛在指標(biāo)；剩余采食量和飼料轉(zhuǎn)化率與瘤胃組織形態(tài)學(xué)指標(biāo)無(wú)顯著相關(guān)，采食量和平均日增重與瘤胃乳頭長(zhǎng)度和肌層厚度呈顯著正相關(guān)，表明羔羊瘤胃組織形態(tài)對(duì)采食量和增重有顯著影響，但其進(jìn)一步的作用機(jī)制有待深入研究。

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Association of Rumen Histomorphology of Sheep with Different Feed Efficiencies

ZHANG DeYin1, ZHANG XiaoXue1, LI FaDi1,2, LI Chong1,2, LI GuoZe1, ZHANG YuKun1, LI XiaoLong1, SONG QiZhi1, ZHAO Yuan1, LIU XiaoQing1, MA LiangQiang1, WANG WeiMin

(1College of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070;2Engineering Laboratory of Sheep Breeding and Reproduction Biotechnology in Gansu Province, Minqin 733300)

【】The individual pens was used to determine individual feed efficiency-related traits and rumen morphology indexes, and the association of feed efficiency of sheep and rumen histomorphology was discussed, so as to provide fundamental data for analyzing the influencing factors of sheep feed efficiency traits. 【】One hundred and eighty-seven Hu lambs with the similar birthday age, good growth and available pedigrees were selected randomly, and all lambs were transferred to the housed indoors in individual pens after weaning at 56 days, the lambs were subjected to a 14 days adaptation period. The pre-test period was 10 days and the experimental period was 100 days, during which all lambs were fed pellet feed and had free access to food and fresh drinking water. Lambs were weighed before feeding in the morning at 80 and 100 days, and feed intake (FI) were measured during 80-180 days. Average daily gain (ADG), metabolic body weight (MBW), feed conversion rate (FCR) and residual feed intake (RFI) were calculated and the descriptive statistics were carried out. The lambs were slaughtered at 180 days, and rumen abdominal sac tissue was collected, and stored in 4% formaldehyde solution for making tissue sections. The length, width and muscle thickness of the rumen papilla were observed. Finally, correlation analysis and variance analysis were carried out for the traits related to feed efficiency.【】The variation coefficients of feed efficiency-related traits were all greater than 10%, and the difference of the individuals with the largest and smallest residual feed intake was 0.57 kg per day. Phenotypic correlation analysis of feed efficiency-related traits showed that RFI was very significantly positively correlated with FCR (r= 0.68) and FI (r= 0.48) (＜0.01), there was no significant correlation with initial body weight (r=0) final body weight (r= -0.01) and average daily gain (r= -0.02) (＞0.05). The correlation analysis between feed efficiency and rumen histomorphology was found that the length of the rumen papilla was significantly or very significantly positively correlated with average daily gain, feed intake, initial body weight and final body weight (＜0.05 or＜0.01), while there were no significant differences in length and width of rumen papilla (＞0.05). The feed intake and feed conversion rate of lambs in the High-RFI group were significantly higher than those in the Low-RFI group (＜0.01), and the muscle thickness was significantly higher than that of the Medium-RFI group (＜0.05). There were significantly or extremely significantly differences in residual feed intake, feed intake, ADG, initial body weight, final body weight and the length of rumen in different FCR groups (＜0.05 or＜0.01), there was no significant difference between the rumen muscular thickness and the width of rumen papilla (＞0.05). Among them, the residual feed intake, feed intake, ADG, initial body weight and final body weight of the lambs in the High-FCR group were significantly or extremely significantly higher than those in the Low-FCR group (＜0.05 or＜0.01), The length of the rumen papilla in the medium-FCR group was significantly longer than that in the Low-FCR group (＜0.05). There were significant or extremely significant differences in the above indexes of the lambs in different FI groups (＜0.05 or＜0.01), and the residual feed intake, feed conversion rate, ADG, initial body weight, final body weight, muscle thickness and the length of the rumen papilla in the High-FI group were significantly or extremely significantly higher than those in the Low-FI group (＜0.05 or＜0.01). There were significant or extremely significant differences in feed intake, feed conversion rate, initial body weight, final body weight and muscle thickness in different ADG groups (＜0.05 or＜0.01), there was no significant difference between the length and the width of the rumen papilla (＞0.05), the feed intake, residual feed intake, initial body weight, final body weight and muscle thickness of the High-ADG group were significantly or extremely significantly higher than those of the Low-ADG group, and the feed conversion rate was significantly lower than that of the Low-ADG group.【】There was a significant positive correlation between residual feed intake and the traits related to feed efficiency such as feed intake and feed conversion rate, indicating that it could be used as a potential index to measure feed efficiency. There was no significant correlation between the residual feed intake and feed conversion rate and the rumen histopathology. Feed intake and average daily gain were significantly positively correlated with the length of the rumen papilla and the muscular thickness, indicating that the morphology of the rumen tissue had significant effects on feed intake and body weight gain. However, the mechanism of action remains to be further studied.

residual feed intake; feed conversion rate；rumen; histomorphology; Hu sheep

10.3864/j.issn.0578-1752.2020.24.014

2020-01-02；

2020-09-05

國(guó)家自然科學(xué)基金（31560625）、國(guó)家自然科學(xué)基金（31760651）、國(guó)家畜禽良種聯(lián)合攻關(guān)計(jì)劃（125D0101）、國(guó)家肉羊產(chǎn)業(yè)技術(shù)體系（CARS-38）

張德印，E-mail：1547767138@qq.com。通信作者王維民，E-mail：wangwm@gsau.edu.cn

（責(zé)任編輯 林鑒非）