发酵湿玉米纤维饲料同常用粗饲料在瘤胃降解特性和小肠消化率上的比较研究

试验旨在研究发酵湿玉米纤维饲料同常用粗饲料在瘤胃降解特性和小肠消化率的异同点。选用2头体重550 kg左右,安装有永久性瘤胃瘘管的荷斯坦奶牛作为试验动物,采用常规方法测定发酵湿玉米纤维饲料(FWCGF)、湿玉米纤维饲料(WCGF)、苜蓿和全株玉米青贮的营养价值,采用尼龙袋法和三步体外法测定4种饲料的干物质(DM)、粗蛋白(CP)、中性洗涤纤维(NDF)的瘤胃降解率以及瘤胃非降解蛋白(RUP)的小肠消化率。试验结果表明:(1)FWCGF的CP含量显著高于WCGF、苜蓿和全株玉米青贮(P0.05);苜蓿的SP、NPN、NDICP和ADF含量最高,FWCGF的ADF含量显著低于WCGF(P0.05);FWCGF的EE含量显著高于WCGF的EE含量(P0.05)。(2)4种饲料的DM瘤胃降解率和有效降解率由高到低的顺序是FWCGFWCGF苜蓿全株玉米青贮;4种饲料的CP有效降解率由高到低的顺序是FWCGFWCGF全株玉米青贮苜蓿;4种饲料的NDF有效降解率由高到低的顺序是全株玉米青贮苜蓿FWCGFWCGF。(3)WCGF和FWCGF的RUP小肠消化率和小肠可消化蛋白质差异不显著(P0.05),苜蓿最高。综上可以得出,FWCGF和WCGF均含有高含量的可利用蛋白质和可利用纤维,并且FWCGF可以提高可利用蛋白的含量,有较高的DM和CP的瘤胃降解率,通过酿酒酵母发酵处理可有效保持WCGF的营养成分。     

湿玉米纤维饲料的营养价值评定

试验通过对湿玉米纤维饲料(WCGF)与常用粗饲料(羊草、全株玉米青贮和苜蓿),以及与玉米营养成分进行比较,对WCGF营养价值进行系统的评定。通过开展WCGF与3种常用粗饲料(羊草、全株玉米青贮和苜蓿),以及与玉米的化学组分、氨基酸组成、瘤胃降解率进行比较研究。试验结果表明:与常用粗饲料相比,WCGF粗蛋白(CP)高于羊草和玉米青贮(P<0.05)。中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和钙(Ca)处于最低水平(P<0.05),而磷(P)含量处于最高水平,不可利用纤维(CC)(%CHO)含量低(P<0.05),谷氨酸(Glu)、亮氨酸(Leu)和脯氨酸(Pro)则高于其他3种常用粗饲料(P<0.05)。有效降解CP和有效降解NDF均高于其他3种常用粗饲料(P<0.05);与玉米营养成分相比,WC-GF淀粉含量显著低于玉米(P<0.05);CP、NDF、ADF、P和灰分含量显著高于玉米(P<0.05);WCGF氨基酸含量、中度降解蛋白(PB2)(%CP)、可利用纤维(CB2)(%CHO)和有效降解CP显著高于玉米(P<0.05)。结论:WCGF含有较高含量的可消化纤维、粗蛋白和氨基酸,是理想的非饲草的纤维性饲料。     

应用康奈尔净碳水化合物-蛋白质体系和NRC模型比较常用粗饲料和玉米纤维饲料的营养价值

本试验旨在应用康奈尔净碳水化合物-蛋白质体系(CNCPS)和NRC模型比较玉米纤维饲料(DCGF)与奶牛常用粗饲料(苜蓿、玉米青贮、羊草)营养价值,进而分析DCGF作为奶牛纤维饲料资源的可行性。采集东北地区不同牧场的饲料样本,测定营养成分后利用CNCPS模型对各饲料蛋白质和碳水化合物进行剖分,并预测各饲料对奶牛的潜在营养物质供给量,同时利用NRC模型对4种饲料的可消化养分和能值进行估测计算。结果表明:1)DCGF中粗蛋白质(CP)含量显著高于玉米青贮和羊草(P0.05),中性洗涤纤维(NDF)含量显著高于苜蓿(P0.05),且酸性洗涤纤维(ADF)、酸性洗涤木质素(ADL)含量显著低于其他3种粗饲料(P0.05)。2)DCGF快速降解真蛋白质(PB1)和中速降解真蛋白质(PB2)含量显著低于苜蓿(P0.05);中速降解碳水化合物(CB1)和慢速降解碳水化合物(CB2)含量显著高于其他3种粗饲料(P0.05)。3)苜蓿的可代谢蛋白质(MP)含量最高,其次为DCGF。4)DCGF在维持水平下总可消化养分(TDNm)和净能均最高。结果提示,DCGF具有较高的营养价值,可以作为奶牛纤维类高蛋白质饲料替代奶牛饲粮中部分粗饲料,缓解我国优质粗饲料、蛋白质饲料资源紧缺的压力。     

不同发酵时间对全混合日粮的瘤胃降解特性以及小肠消化率的影响

试验旨在研究发酵0、3、7、15、30 d的全混合日粮(TMR)对瘤胃降解特性以及小肠消化率的影响。选用3头体重为550 kg左右、安装有永久性瘤胃瘘管的荷斯坦奶牛,采用尼龙袋法和三步体外法测定发酵全混合日粮(FTMR)的干物质(DM)、粗蛋白质(CP)、中性洗涤纤维(NDF)的瘤胃降解率以及瘤胃未降解蛋白(RUP)的小肠消化率。结果表明:随着发酵时间的延长,FTMR饲料的DM含量显著降低(P<0.05);随着发酵时间的延长,显著提高FTMR的DM、CP、NDF的瘤胃降解率(P<0.05)和CP、NDF的快速降解部分(P <0.05);同时发酵显著降低RUP的小肠消化率(P <0.05)。综上可知,全混合日粮提高了DM、CP和NDF在瘤胃中的瘤胃降解率,15、30 d的FTMR各营养成分的瘤胃降解性较好;RUP的小肠消化率随发酵时间的延长开始逐渐降低,7d之后降低最为明显。因此,应控制好TMR的发酵时间,以便更有效地利用饲料资源。     

6种饲料原料瘤胃降解特性和瘤胃非降解蛋白质的小肠消化率

本试验旨在研究新疆地区玉米青贮、棉籽壳、苜蓿草粉、苜蓿干草、葡萄籽粕、蕃茄酱渣6种奶牛饲料原料的瘤胃降解特性和瘤胃非降解蛋白质(RUP)的小肠消化率(Idg)。选用3头装有永久性瘤胃瘘管的泌乳荷斯坦奶牛,采用尼龙袋法和改进三步体外法测定饲料原料的干物质(DM)、粗蛋白质(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的瘤胃降解特性以及RUP的Idg和小肠可消化粗蛋白质(IDCP)含量。结果表明:1)苜蓿草粉和玉米青贮的DM有效降解率最高,显著高于次之的苜蓿干草、番茄酱渣(P0.05),葡萄籽粕、棉籽壳最低,显著低于其他原料(P0.05);CP有效降解率为番茄酱渣苜蓿草粉玉米青贮苜蓿干草棉籽壳葡萄籽粕,各原料间差异显著(P0.05);NDF有效降解率为玉米青贮苜蓿草粉棉籽壳苜蓿干草番茄酱渣葡萄籽粕,各组饲料原料间差异显著(P0.05);ADF有效降解率为玉米青贮棉籽壳苜蓿干草番茄酱渣苜蓿草粉葡萄籽粕,各组饲料原料间差异显著(P0.05)。2)苜蓿草粉RUP的Idg和IDCP含量最高,Idg显著高于依次降低的苜蓿干草、玉米青贮、番茄酱渣、葡萄籽粕、棉籽壳(P0.05),IDCP含量与苜蓿干草差异不显著(P0.05),显著高于依次降低的玉米青贮、番茄酱渣、葡萄籽粕、棉籽壳(P0.05)。综上所述,不同饲料原料具有不同的瘤胃降解特性,进入小肠IDCP的含量也不同。玉米青贮的DM、NDF和ADF在瘤胃的有效降解率较高,苜蓿草粉RUP的Idg较高,苜蓿草粉和苜蓿干草的IDCP含量较高。     

山东省羊常用粗饲料的粗蛋白瘤胃降解率和小肠消化率研究

试验旨在研究山东省羊常用粗饲料中粗蛋白的瘤胃降解特性和小肠降解特性。测定山东省17个地市10种羊常用粗饲料109个样本的常规养分含量,运用尼龙袋法测定粗饲料干物质(DM)、粗蛋白(CP)的48 h瘤胃降解率和瘤胃非降解蛋白(RUP),用改进体外三步法测定DM和RUP小肠消化率及小肠可消化蛋白(uCP)。最终建立山东省羊常用粗饲料瘤胃降解率、小肠消化率、RUP及uCP与常规养分间的预测模型。结果表明:苜蓿和黑麦草(冬牧70)的瘤胃降解率和小肠消化率均较高,除地瓜秧和花生秧外,秸秆类饲料的瘤胃降解率和小肠消化率普遍较低,粗饲料DM、CP的瘤胃降解率和瘤胃降解残渣的DM、RUP小肠消化率及RUP和uCP含量均受到饲料中粗蛋白和纤维物质含量的影响,即与CP含量呈正相关,与中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)含量呈负相关;粗饲料原料的DM瘤胃降解率与CP瘤胃降解率间存在正相关关系。由此可见,利用粗饲料的常规养分可预测其DM和CP的瘤胃降解率、DM和RUP小肠消化率、RUP和uCP含量。     

奶牛对不同糟渣类饲料营养成分的瘤胃降解率和小肠消化率对比研究

本试验旨在对比奶牛对不同糟渣类饲料(玉米酒糟、高粱酒糟、醋糟、糖糟、啤酒糟)的营养成分瘤胃降解率和小肠消化率.选用3只装有永久性瘤胃瘘管的中国荷斯坦奶牛,用尼龙袋法测定干物质(DM)、粗蛋白质(CP)、必需氨基酸(EAA)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)在不同时间点的瘤胃降解率和小肠消化率.结果表明:1...     

干酒糟及其可溶物中糠氨酸含量与瘤胃降解特性和瘤胃非降解蛋白质的小肠消化率的相关性研究

本试验旨在验证美拉德反应中间产物糠氨酸含量与不同程度热加工干酒糟及其可溶物(DDGS)的瘤胃降解特性及瘤胃非降解蛋白质的小肠消化率之间存在相关性并建立回归方程,并与酸性洗涤不溶蛋白质作为饲料热处理敏感指标进行比较。试验采用高效液相色谱法测定不同热处理DDGS中糠氨酸含量,采用尼龙袋法测定干物质和粗蛋白质瘤胃降解特性并采用改进的三步体外法测定瘤胃非降解蛋白质的小肠消化率,分析两者之间相关性并建立回归方程。结果表明:1)随着加热程度的增加,DDGS中糠氨酸和酸性洗涤不溶蛋白质含量显著增加(P0.05),干物质和粗蛋白质瘤胃有效降解率及瘤胃非降解蛋白质的小肠消化率降低,且不同处理之间存在显著差异(P0.05)。2)糠氨酸与酸性洗涤不溶蛋白质含量均与干物质和粗蛋白质瘤胃培养可溶部分(r=-0.72 vs.-0.60; r=-0.60 vs.-0.51)、不可降解部分(r=0.96 vs.0.84; r=0.96 vs. 0.85)、有效降解率(r=-0.62 vs.-0.51; r=-0.72 vs.-0.61)以及瘤胃非降解蛋白质的小肠消化率(r=-0.52 vs.-0.57)存在显著相关性(P0.05),并可建立回归预测方程。3)糠氨酸含量较酸性洗涤不溶蛋白质含量与瘤胃降解特性具有更高的相关性,二者与瘤胃非降解蛋白质的小肠消化率、总可消化蛋白质含量之间的相关性相似,但糠氨酸含量与小肠可消化蛋白质含量具有更高相关性(r=0.67)。综上,不同热处理DDGS中糠氨酸含量与瘤胃降解特性和小肠消化率存在相关关系,并可建立回归方程。糠氨酸含量较酸洗洗涤不溶蛋白质含量更适合作为评价饲料热加工程度的关键指标。     

发酵湿玉米纤维饲料和几种常用粗饲料营养价值分析

试验旨在运用康奈尔净碳水化合物—蛋白质体系(CNCPS)和NRC模型分析比较发酵湿玉米纤维饲料(FWCGF)、湿玉米纤维饲料(WCGF)、苜蓿和青贮玉米(CS)的营养价值,预测FWCGF替代或部分替代反刍动物常用粗饲料的可行性。从黑龙江省不同牧场采集饲料样品,测出4种原料的常规营养成分,然后利用CNCPS模型剖分4种原料的蛋白质和碳水化合物组分,再通过NRC模型估测待测饲料的可消化养分和能值。结果表明:FWCGF的粗蛋白质含量高于其他3种饲料(P<0.05),FWCGF的酸性洗涤纤维含量最低(P<0.05);FWCGF的真蛋白质最高(P<0.05),FWCGF的瘤胃可降解蛋白质、可代谢蛋白质、总可消化养分和净能最高(P<0.05)。由此可见,相对于其他原料,FWCGF的可利用蛋白和纤维含量丰富,是奶牛日粮中纤维类、蛋白类粗饲料的有效替代品。     

不同食品加工副产品的瘤胃降解特性与小肠消化率的测定

本试验旨在测定胡麻饼(FM)、DDGS、麦麸皮(WB)、白酒糟(DG)、干啤酒糟(DBG)、苹果渣(AP)的瘤胃降解规律以及小肠消化率。试验选用3头体重为650 kg左右、安装有永久性瘤胃瘘管的荷斯坦奶牛,采用尼龙袋法测定其有机物(OM)、粗蛋白(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的瘤胃降解率以及粗蛋白(CP)和氨基酸(AA)的小肠消化率。结果表明:不同食品加工副产品常规营养成分存在差异;不同食品加工副产品的瘤胃有效降解率之间差异显著(P0.05),高低顺序为OM:WBDDGSDBGAPFMDG,CP:WBDBGFMAPDDGSDG,NDF:WBFMDDGSDBGAPDG,ADF:DBGAPFMDDGSWBDG;测定样品的CP和各种AA成分小肠消化率差异显著(P0.05),其中CP和TAA高低顺序为CP:FMDDGSWBDBGDGAP,TAA:FMDDGSDGWBDBDAP。由此可见,不同食品加工副产品的营养成分含量、瘤胃降解特性不同,为小肠提供可消化粗蛋白潜力也不同。     

Energy value of corn wet milling by-product feeds for finishing ruminants

Five trials were conducted to evaluate the energy value of corn wet milling by-products in finishing diets. In trials 1 (45 finishing lambs, 34 kg) and 2 (70 digestion wethers, 32 kg), Rambouillet X Suffolk lambs fed corn gained faster (P less than .10), more efficiently (P less than .10) and had higher (P less than .01) digestibilities of neutral and acid detergent fiber (NDF, ADF) and starch than lambs fed dry corn gluten feed (DCGF). Lambs fed wet corn gluten feed (WCGF) consumed less feed (trial 1, P less than .05; trial 2, P less than .01), were more efficient (P less than .01) NDF and ADF digestibilities than lambs fed DCGF. Starch, NDF and ADF digestion were higher (P less than .01) for lambs fed WCGF vs wet corn bran (WCB). Lambs fed WCGF gained faster (P less than .10) and consumed more (trial 1, P = .12; trial 2, P less than .10) feed than lambs fed WCB. Dried corn bran increased (trial 1, P less than .05; trial 2, P less than .01) intake and increased (P less than .01) dry matter digestion (DMD) compared with WCB. In trial 3, rates of in vitro dry matter and NDF disappearance were similar among by-product feeds. In trial 4 (50 individually fed Shorthorn-Hereford-Angus steers, 316 kg), steers fed WCGF tended to consume more (P = .14) feed than steers fed DCGF. Corn gluten feed (CGF) replacing 0 to 46% corn decreased gain (linear, P less than .05) and DMD (linear, P less than .10), while starch digestion was highest for 23% CGF (quadratic, P less than .01). A level X CGF type interaction (P = .15) occurred for efficiency due to the lower gain of steers fed 46% DCGF. The efficiency of CGF utilization was 97% that of corn when WCGF replaced 23 or 46% corn or DCGF replaced 23% corn. Dry CGF replacing 46% corn had 87% the value of corn. In trial 5 (186 Hereford-Angus cattle, 310 kg), DCGF replacing 25 and 50% corn had 97 to 100% the efficiency of corn, while intake and gain were not affected. Dry CGF replacing 25 and 50% corn silage increased (linear, P less than .05) intake 11.3% and gain 13.8%. In ruminants, CGF is highly digestible and feed efficiency is similar to corn when WCGF is fed up to 50% of the grain component or when DCGF is fed up to 25% of the grain component.     

奶牛常用蛋白质饲料和粗饲料的瘤胃降解特性研究

本研究旨在评定不同蛋白质饲料(豆粕、双低菜籽粕、膨化大豆、玉米蛋白粉、棉籽粕)和粗饲料(苜蓿干草、全株玉米青贮、燕麦草、苜蓿青贮、羊草)的营养价值,并研究其奶牛瘤胃降解特性.选择5头安装永久性瘤胃瘘管的健康荷斯坦牛,采用尼龙袋评定法评定饲料瘤胃有效降解率和动态降解率.结果表明:1)各蛋白质饲料干物质(DM)含量差异不显...     

Nutrient digestibility and energy value of sheep rations differing in protein level, main protein source and non-forage fibre source

Two in vivo digestion trials were conducted to evaluate the effects of diet's crude protein (CP) level, N degradability, and non-forage fibre source (NFFS) on nutrient digestibility and energy value of sheep rations. In each trial, rams were fed four isocaloric and isofibrous rations, differing in main protein and/or NFFS source. At the first trial, mean CP/metabolizable energy (ME) ratio of the diets was 17 g/MJ ME and at the second trial, 13 g/MJ ME. At both trials, the first ration contained cotton seed cake (CSC) and wheat bran (WB), the second CSC and corn gluten feed (CGF), the third corn gluten meal (CGM) and WB and the fourth CGM and CGF. Data of both trials were analysed in common as 2 x 2 x 2 factorial experimental design. Low N degradability (CGM) had positive effect on CP, neutral detergent fibre (NDF) and acid detergent fibre (ADF) digestibility of the ration. Those results suggest that an increase in rumen undegradable protein (RUP) content does not negatively affect nutrient digestibility of sheep rations. Corn gluten feed significantly elevated crude fibre (CF) digestibility, in comparison with WB. Rations having high CP/ME ratio had higher digestibility of CP in comparison with those having low CP/ME ratio; the opposite was true for ether extract, CF, NDF and ADF digestibilities. CP level x N degradability interaction negatively affected energy value of the rations that had high CP level and high N degradability. Former suggest that when CP content is high then N degradability should be low otherwise ration's ME is negatively affected. CP digestibility and coefficient q of the rations containing WB and having high N degradability (N degradability x NFFS interaction) were the lowest suggesting that the combination of CSC and WB negatively affected CP digestibility and energy value of the ration. This could be explained by a reduced microbial CP synthesis, or lower RUP digestibility or both.     

应用康奈尔净碳水化合物-蛋白质体系和NRC模型评价4种粮食加工副产物的营养价值

本试验旨在应用康奈尔净碳水化合物-蛋白质体系(CNCPS)和NRC模型评价4种粮食加工副产物的营养价值。从东北地区4个不同牧场采集了玉米纤维饲料、大豆皮、甜菜粕和豆渣4种粮食加工副产物,测定其营养成分,应用CNCPS模型对蛋白质和碳水化合物组分进行剖分,并预测其潜在营养价值供给量,应用NRC模型估测可消化养分和能值。结果表明:1)中性洗涤纤维(NDF)的含量由高到低依次为大豆皮、甜菜粕、玉米纤维饲料和豆渣;非蛋白氮(NPN)的含量由高到低依次为玉米纤维饲料、豆渣、甜菜粕和大豆皮;甜菜粕的酸性洗涤不溶粗蛋白质(ADICP)含量最高,其余依次为大豆皮、豆渣和玉米纤维饲料,其中玉米纤维饲料和豆渣的ADICP含量差异不显著(P0.05)。2)非蛋白氮(PA,即NPN)含量由高到低依次为玉米纤维饲料、豆渣、甜菜粕和大豆皮;真蛋白质(PB)含量由高到低依次为大豆皮、甜菜粕、豆渣和玉米纤维饲料;不可降解氮(PC)的含量由高到低依次为豆渣、甜菜粕、大豆皮和玉米纤维饲料。3)可代谢蛋白质(MP)含量由高到低依次为豆渣、大豆皮、甜菜粕和玉米纤维饲料。4)玉米纤维饲料和豆渣的维持水平总可消化养分(TDNm)含量较高,二者差异不显著(P0.05);生产水平泌乳净能(NELP)值由高到低依次为豆渣、玉米纤维饲料、大豆皮和甜菜粕,其中玉米纤维饲料的NELP值与豆渣、大豆皮差异均不显著(P0.05);生产水平代谢能(MEP)值由高到低依次为豆渣、玉米纤维饲料、甜菜粕和大豆皮。由此可见,玉米纤维饲料和大豆皮可以作为奶牛的纤维源饲料;豆渣的过瘤胃蛋白质(RUP)、MP含量最高,可以作为奶牛的蛋白质源饲料。4种粮食加工副产物的能值由高到低依次为豆渣、玉米纤维饲料、大豆皮、甜菜粕。     

奶牛常用粗饲料的瘤胃降解规律

本试验旨在研究 ２种苜蓿［黑龙江公农 １号苜蓿、美国安德森（Ａｎｄｅｒｓｏｎ）一级苜蓿］、黑龙江 ２种含杂量不同羊草（杂草率分别为 １０％、３４％）、全株玉米青贮、玉米秸秆青贮和玉米秸秆共 ７种粗饲料的瘤胃降解特性。试验选用 ８头装有永久性瘤胃瘘管的荷斯坦奶牛,采用尼龙袋法评定其干物质（ＤＭ）、粗蛋白质（ＣＰ）和中性洗涤纤维（ＮＤＦ）的瘤胃降解率和有效降解率。结果表明,美国安德森一级苜蓿、全株玉米青贮和黑龙江公农 １号苜蓿三者 ７２ｈＤＭ 降解率差异不显著（Ｐ＞０．０５）,并显著高于其他 ４种粗饲料（Ｐ＜０．０５）,而 ＤＭ有效降解率以美国安德森一级苜蓿最高,并与依次降低的黑龙江公农 １号苜蓿、全株玉米青贮和玉米秸秆青贮差异显著（Ｐ＜０．０５）,羊草与玉米秸秆的 ＤＭ有效降解率显著低于其他粗饲料（Ｐ＜０．０５）。７２ｈＣＰ降解率及有效降解率以美国安德森一级苜蓿最高,且降解率与依次降低的黑龙江公农 １号苜蓿、全株玉米青贮、玉米秸秆青贮、杂草率为 １０％的羊草、玉米秸秆和杂草率为 ３４％的羊草间差异显著（Ｐ＜０．０５）。全株玉米青贮、玉米秸秆青贮 ７２ｈＮＤＦ降解率显著高于其他粗饲料（Ｐ＜０．０５）;而有效降解率以 ２种苜蓿较高,其次为玉米秸秆青贮与全株玉米青贮;降解率和有效降解率最低的均为杂草率为 ３４％的羊草。因此,从 ７种粗饲料在奶牛瘤胃的消化特性来看：１）美国安德森一级苜蓿营养价值最高,杂草率为 ３４％的羊草与玉米秸秆营养价值较低;２）羊草的品质受杂草率的影响;３）青贮能改善玉米秸秆的品质。     

断奶仔猪饲粮中玉米蛋白粉配合鲜味剂替代肠膜蛋白粉的研究

本试验旨在研究饲粮中玉米蛋白粉配合鲜味剂替代肠膜蛋白粉对断奶仔猪生长性能、养分和氨基酸表观消化率、血清激素指标及粪便菌群结构的影响,以研究断奶仔猪饲粮中玉米蛋白粉配合鲜味剂能否起到替代肠膜蛋白粉的作用.试验采用2×2析因设计,2个因素分别为蛋白质饲料原料种类(肠膜蛋白粉和玉米蛋白粉)和鲜味剂[添加(0.2％)和无添加]...     

Neutral detergent fiber increases endogenous ileal losses but has no effect on ileal digestibility of amino acids in growing pigs

Two experiments were conducted to determine the effect of neutral detergent fiber (NDF) on endogenous amino acids and protein ileal losses; and also apparent ileal digestibility (AID), and standardized ileal digestibility (SID) of amino acids and crude protein. Sixteen barrows were fed four protein‐free diets containing graded NDF levels in Experiment 1. NDF was a mixture of sugarcane bagasse and corn leaves (SBCL). Twenty‐four barrows were fed diets with soybean protein concentrate (SPC) or casein as protein sources and SBCL or corncobs (CC) as NDF sources in Experiment 2. In Experiment 1, a linear increase (P < 0.05) in endogenous amino acid and protein ileal losses was observed with increased NDF levels, except for arginine, histidine, methionine and proline. In Experiment 2, protein (P < 0.001) and NDF (P < 0.01) sources significantly affected AID of dry matter, which was higher in casein diets (71.7%) and CC diets (70.7%). Protein and NDF sources significantly affected (P < 0.05) SID of crude protein, which was higher in casein diets (92.8%) and CC diets (92.7%). NDF source had no effect (P > 0.05) on SID of amino acids. Overall, this study showed that NDF increased endogenous amino acid and protein ileal losses, but did not affect ileal digestibility of amino acids.     

Effects of forage particle size, level of feed intake and supplemental protein degradability on microbial protein synthesis and site of nutrient digestion in steers

A 2(3) factorial arrangement of treatments was used to study main effects and interactions between particle size of prairie hay (chopped vs ground), two levels of feed intake (60 and 90% of ad libitum) and ruminal degradability of protein sources [dry corn gluten feed (DCGF) vs dry distillers grains (DDG)] on ruminal and total tract digestion in eight ruminal- and duodenal-cannulated steers. Steers were fed every 2 h to approach steady-state feeding conditions. Steers fed ground hay diets digested higher (P less than .05) percentages of total digestible organic matter (OM) and neutral detergent fiber (NDF) in the rumen and had lower (P less than .05) nonammonia-nonbacterial N (NANBN) flows to the duodenum than did those fed chopped hay, probably because greater surface area of ground hay allowed more extensive ruminal fermentation. Protein source X intake interactions were noted for ruminal OM and NDF digestion when expressed as percentages of total digestion. At low intakes, steers fed DCGF had higher (P less than .05) percentages of total digestible OM and NDF disappearing in the rumen than did those fed DDG. Steers fed DCGF had lower total N, NANBN and total amino acid (AA) flows at the duodenum than did those fed DDG, indicating that less DCGF protein escaped ruminal degradation. Steers fed DDG had greater (P less than .05) total tract NDF digestion, suggesting that escape protein from DDG may stimulate hindgut fermentation and thereby affect site and extent of nutrient digestion. Regression analysis indicated that extent of ruminal fermentation and efficiency of microbial growth in vivo are associated with ruminal rates of passage within individual animals. When steers were fed at high-intake levels (1.6% of body weight), ruminal dilution rates were not increased (P less than .05) due to forage particle size or level of intake treatments, accounting, in part, for the lack of expected treatment differences in efficiency of bacterial growth and duodenal N flow, and for the low number of interactions between main effects.