西南大学学报 (自然科学版)  2020, Vol. 42 Issue (2): 8-14.  DOI: 10.13718/j.cnki.xdzk.2020.02.002
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  • 不同剩余采食量水平的安格斯牛生长性状差异性分析    [PDF全文]
    杨朝云1, 康晓龙1, 淡新刚1, 周靖航1, 卢鑫1, 叶连萌1, 赵国丽1,2, 李鹏1,2, 史远刚1,2    
    1. 宁夏大学 农学院, 银川 750021;
    2. 宁夏现代牛业工程技术研究中心, 银川 750021
    摘要:为探究不同剩余采食量对肉牛生长性能的影响,选用体质量、年龄相近的30头安格斯牛进行81 d的饲养试验.试验结束后利用个体采食量(FI)对平均日增质量(ADG)和平均中期代谢体质量(MMBW)的回归分析估计出个体预期采食量(EFI),利用FIEFI之差计算出30头试验牛的剩余采食量,并分为低剩余采食量组(LRFI组)和高剩余采食量组(HRFI组).采用SAS 9.4中TTEST过程对LRFI组和HRFI组肉牛生长数据进行均值的差异性检验;采用SAS 9.4中CORR过程对LRFI组和HRFI组肉牛各生长数据进行相关性系数计算并作相应的显著性检验.结果表明:在所涉及的指标中,HRFI组与LRFI组间仅FI差异有统计学意义(p < 0.01),其余指标差异均未达到统计学意义;LRFI组的RFI与腰角宽存在显著正相关关系(r=0.61,p < 0.05)、与管围和FI之间存在极显著正相关关系(p < 0.01),相关系数分别为0.71,0.78.得出LRFI组肉牛饲料转化效率高于HRFI组,较HRFI组节约8.8%的FI;且本研究涉及的各个生长指标差异均未达到显著水平.
    关键词剩余采食量    生长性能    平均日增质量    安格斯牛    

    饲料利用率是指动物饲料摄入与产品产出之间的比例关系.在肉牛生产行业中,饲养成本高达总成本的84%[1],因此提高饲料效率能够降低肉牛生产成本.近几十年来,研究人员提出了一些衡量饲料利用率的方法,但这些方法均过于复杂且每种方法都有着鲜明的特性[2-6].在这些方法中,有的缺乏将肉牛维持需要及生产需要能值进行精细的剖分[2];有的与生长性状之间存在着一定的相关性,使得在提高饲料利用率的同时降低了某些与之呈负相关的生长性状[7];甚至也还有一些方法利用不同变量之间的方差比率去评价饲料效率,降低了饲料利用效率的客观性[8].

    Koch等[2]于1963年提出利用剩余采食量(Residual Feed Intake,RFI)作为衡量饲料利用效率的指标. RFI是动物实际采食量(actual feed intake,AFI)和用于维持及增质量需要的预期采食量(expect feed intake,EFA)之差,即RFI=AFI-EFA.研究表明[3, 9-10]RFI和生长指标如平均日增质量、体质量等生长性状相互独立,与饲料转化率和干物质采食量之间存在着显著的相关性. RFI是一个中等遗传力性状[11],具有高剩余采食量动物(High Residual Feed Intake,HRFI)对饲料利用率低、低剩余采食量动物(Low Residual Feed Intake,LRFI)饲料利用率高的特点[5].利用RFI作为衡量饲料利用效率指标不仅能排除动物生长性状及生长速率的影响,也能准确反映出动物对饲料的利用率[12]. Connor等[13]对254头奶牛进行RFI测定,发现最低RFI的奶牛比最高RFI的奶牛少消耗15%的饲料;在肉牛中[9, 14-16],LRFI组肉牛对饲料的消耗显著低于HRFI组肉牛,表明LRFI组的个体饲料利用效率高于HRFI组的牛,拥有更低料肉比.因此,通过对低RFI动物个体的人工选育有利于提高家畜饲料利用效率,同时对降低家畜的饲养成本和饲料成本有着较大的潜力与优势[17].本研究旨在探究同一品种不同剩余采食量组的生长性能差异性以及不同品种相同剩余采食量组间各生长指标的比较,以期为今后开展肉牛RFI研究及高效饲料利用率肉牛个体选育提供理论支撑.

    1 材料与方法 1.1 试验对象

    选取宁夏某养殖场健康状况良好、年龄和体质量相近的安格斯公牛(Angus cattle,A)共30头,其初始体质量为266.7±35.7 kg.

    1.2 饲养要求

    试验安格斯牛群体按照NRC(2000)动物营养标准进行饲养,每天上午07:00和下午14:00限栏饲喂.采食1.5 h/次,每天喂食2次,自由饮水.每周进行2次个体采食数据的收集.

    1.3 数据收集

    采食量(kg):每周周日早、晚各进行1次采食量(Feed Intake,FI)数据收集,取两次算术平均值为采食量值.体质量(kg):每20 d对牛只进行1次空腹称质量,每头牛重复3次,取算术平均值为体质量值.

    体尺性状记录:每20 d进行1次体尺性状的测量.包括:体高(cm)、十字部高(cm)、体斜长(cm)、胸围(cm)、胸深(cm)、腹围(cm)、腰高、管围(cm)、腰角宽(cm)、尻长(cm)、尻宽(cm).详细测定办法见文献[18].

    所有生长指标均用试验期内的增量表示.

    1.4 RFI的计算

    利用实验期内(81 d)每个个体采食量观测值和预期采食量之差表示RFI.利用FI对中期代谢体质量(MMBW0.75)和平均日增质量(ADG)进行多元线性回归估算个体EFI,统计分析模型如下:

    $ y = \beta + \alpha MMB{W^{0.75}} + \gamma ADG + \varepsilon $

    其中y为个体FIβ为方程回归截距,αγ分别为MMBW0.75ADG的偏回归相关系数,ε为表型残差.因此EFI可由如下方程式计算:

    $ \widehat {{y_i}} = \widehat \beta + \widehat \alpha MMBW_i^{0.75} + \widehat \gamma AD{G_i} $

    即剩余采食量RFI可由如下公式计算:

    $ RF{I_i} = F{I_i} - \left( {\widehat \beta + \widehat \alpha MMB{W^{0.75}}_i + \widehat \gamma AD{G_i}} \right) $

    式中RFIi为个体i的剩余采食量;FIi为个体i的实际采食量;MMBWi0.75AGGi分别为个体i的中期代谢体质量和平均日增质量;$\widehat \beta , \widehat \alpha , \widehat \gamma $分别为βαγ的估计值.

    计算出个体RFI后,RFI大于0的为HRFI组,小于0的为LRFI组.

    1.5 数据分析

    试验数据利用Excel 2016进行初步整理,利用SAS 9.4软件TTEST过程对LRFI组和HRFI组肉牛生长性状进行均值差异性显著检验,显著水平α=0.05;利用CORR过程对LRFI组和HRFI组肉牛生长性状进行相关性分析并做显著性检验.本文所有表中各生长性状数值均用试验期内的增量表示,结果利用x(平均值)±s(标准差)表示.

    2 结果 2.1 安格斯牛RFI分组结果

    在饲养的30头公牛中,由于疾病原因,淘汰2头,故实际样本量为28头,因此安格斯牛HRFI组的RFI值为1.3,1.2,1.1,1.0,1.0,0.7,0.5,0.5,0.5,0.4,0.4,0.2,0.2,0.2,0.1,0.1;LRFI组的RFI值为-1.7,-1.1,-1.1,-1.0,-0.8,-0.8,-0.8,-0.7,-0.5,-0.3,-0.3,-0.2.计算公式如下:

    $ RFI = FI - (9.102 - 0.772*MMBW + 0.039*ADG) $
    图 1 高、低组安格斯牛RFI散点图
    2.2 HRFI组与LRFI组安格斯牛体尺性状差异性分析

    结果表明,HRFI组与LRFI组的FI差异有统计学意义,HRFI组FI极显著高于LRFI组(p<0.01),即LRFI组每天比HRFI组少采食1.2 kg,占HRFI组日均采食量的8.8%,且体高、十字部高、坐骨端宽、胸围、腹围均高于LRFI组,但差异尚未达到统计学意义. LRFI组体质量、腰高、体斜长、尻长、腰角宽、胸深、管围、平均日增质量(ADG)高于HRFI组,但两组间差异尚未达到统计学意义(表 1).

    表 1 安格斯牛HRFI组与LRFI组的主要生长指标比较分析结果
    2.3 HRFI组和LRFI组安格斯肉牛RFIFIADG与各体尺性状相关性分析

    相关性分析结果表明(表 2),在HRFI组安格斯牛中,RFIFI呈显著正相关(r=0.51,p<0.05),而与本文所测其余生长指标的相关性检验均没有达到统计学意义(|r|<0.27,p>0.05);FI与体高、十字部高、腰高增量及ADG呈显著正相关关系(p<0.05),相关系数分别为0.57,0.74,0.62,0.60,0.62,与体斜长、腰角宽、胸深、胸围、腹围等的增量呈极显著的正相关关系(p<0.01),相关系数分别为0.77,0.76,0.76,0.79,0.71,而与坐骨端宽、管围增量的相关性检验均未达到统计学意义(p>0.05),相关系数分别为0.23,0.43;ADG与本文所测所有生长指标的相关性检验均未达到统计学意义,相关系数在0.20~0.46之间.

    表 2 安格斯牛HRFI组和LRFI组各性状间的相关性及其显著性检验结果

    在LRFI组中,RFI与管围和FI之间存在极显著正相关关系(p<0.01),相关系数分别为0.71,0.78,与腰角宽呈显著的正相关关系(r=0.61,p<0.05),而与本文所测其余生长指标的相关性检验均未达到统计学意义,相关系数在0.08~0.54之间;FI与体高、十字部高、尻长、腰角宽、胸深、胸围、管围等的增量和ADG间存在极显著的相关关系(p<0.01),相关系数分别为0.70,0.80,0.71,0.74,0.81,0.88,0.86,0.74,与腰高、体斜长、腹围等的增量呈显著正相关关系(p<0.05),相关系数分别为0.60,0.61,0.59,与坐骨端宽无显著相关关系(r=0.51,p>0.05);ADG与胸围的增量呈极显著的正相关关系(r=0.61,p<0.01);而与本文所测其余生长指标的相关性检测均未达到统计学意义(p>0.05),相关系数在0.08~0.53之间.

    3 讨论

    选育高饲料利用效率畜禽品种能减少动物对日粮饲料的消耗,达到节粮的目的. RFI主要涉及动物摄食行为、饲料消化、代谢、机体活力、体温调节生理过程.但作为主要经济性状,RFI同样受着遗传因素的调控,随着高通量技术的广泛应用,已有大量文献在全基因组[19-26]、转录组[27-29]及代谢组[30-31]方面开展了畜禽RFI的研究.

    在饲料利用效率和不同水平RFI的研究表明[32-34],LRFI组的动物比HRFI组平均采食量少21%.且RFIADG、以及各生长性状相关性不显著,HRFI组和LRFI组间各生长性状间差异无统计学意义[35-39].

    在本研究中,HRFI组FI极显著高于LRFI组(LRFI组平均FI比HRFI组低8.8%),在测量的各生长性状上差异均未达到统计学意义,但LRFI组在体质量、腰高、体斜长、尻长、腰角宽、胸深、管围、ADG等均高于HRFI组,表明LRFI组对饲料的利用效率高于HRFI组.这与谢云怡等[34]、孙晓玉等[40]、Hegarty等[41]研究结果一致.表明在本研究的安格斯牛群体中,这可能是由于不同RFI水平个体内在的某种机制导致了组间饲料利用效率差异,使得在相同饲养条件下饲喂等量的饲料,获得了不同的饲料报酬.

    4 结论与展望

    在本研究的LRFI组与HRFI组安格斯牛中,LRFI组对饲料消耗较少,达到了极显著水平.而在本研究测定的其他体尺指标上,LRFI组的增量比HRFI组的增量高,但个别指标也低于HRFI组.表明LRFI组在保证其ADG不显著低于HRFI组ADG的情况下,LRFI组消耗较少的饲料,获得较高的饲料报酬,这对今后选育节粮型的家畜有着积极的参考意义.

    不足的是,本研究尚处于RFI相关研究的表型层面,尚未进行与RFI相关的分子发生机理、相关代谢物通路、遗传调控、肉质变化、生理过程等深层次的研究.后续可在本研究的基础上探寻上述提及的5个板块进行验证,为进一步选育节粮型的LRFI品系奠定理论基础.

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    Differential Analysis of Growth Traits in Angus Cattle on Different Levels of Residual Feed Intake
    YANG Chao-yun1, KANG Xiao-long1, DAN Xin-gang1, ZHOU Jing-hang1, LU Xin1, YE Lian-meng1, ZHAO Guo-li1,2, LI Peng1,2, SHI Yuan-gang1,2    
    1. School of Agriculture of Ningxia University, Yinchaun 750021, China;
    2. Ningxia Modern Cattle Engineering Technology Research Center, Yinchuan 750021, China
    Abstract: To explore the effect of different residual feed intake levels on the growth performance in beef cattle, thirty Angus beef cattle of similar weight and age were selected for an 81-d feeding trial in this study. After the experiment was finished, the expected feed intake (EFI) was estimated by regression analysis of individual diet (feed intake, FI) to the average daily weight gain (ADG) and mean medium metabolic weight (MMBW), and then residual feed intake (RFI) of the tested cattle was calculated by the difference between FI and EFI and, ultimately, the tested cattle were divided into a low residual feeding group (LRFI group) and a high residual feeding group (HRFI group). The differential of mean value for growth performance was tested with the TTEST process in SAS 9.4. Correlation coefficient calculation and its significance test of the growth data were carried out by the CORR process in SAS 9.4. The results showed that there were significant differences in FI (p < 0.01) only between HRFI group and LRFI group, and none of the remaining indicators reached the significant level of difference. There was a significant positive correlation between RFI and lumbar width in LRFI group (r=0.61, p < 0.05), and a highly significant positive correlation between tube circumference and FI (p < 0.01), with a correlation coefficient of 0.71 and 0.78, respectively. Conclusion:The feed conversion ratio of LRFI group was higher than that of HRFI group, and the FI was saved by 8.8% compared with the HRFI group. And differences of remaining growth traits involved in this study did not reach a significant level.
    Key words: residual feed intake    growth performance    average daily weight gain (ADG)    Angus cattle    
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