饲用甜高粱和全株玉米青贮对肉羊前胃微生态的影响

本试验旨在探究饲用甜高粱青贮（sweet sorghum silage, SS）和全株玉米青贮（whole-plant corn silage, CS）对肉羊前胃微生态的影响。选择健康的3~4月龄杜泊母羊［（33.40±1.68） kg］14只,随机分为2组,每组7只羊,每只羊为1个重复,分别喂甜高粱青贮（SS组）和玉米青贮（CS组）,单栏饲喂并自由饮水。预饲期15 d,正试期90 d,在正试期测定并计算生长性能指标,正试期结束后,每组选取4只羊进行屠宰,采集前胃（瘤胃、网胃和瓣胃）食糜和组织样品,对前胃发酵参数、微生物表达量、上皮颜色和组织结构进行观察和测定。结果表明：1）CS组肉羊的干物质采食量显著高于SS组（P<0.05）。2）甜高粱青贮和玉米青贮育肥肉羊90 d后,对前胃的pH值未产生显著影响（P>0.05）;在网胃内容物中,SS组肉羊氨氮浓度显著高于CS组（P<0.05）,CS组肉羊丁酸含量显著高于SS组（P<0.05）;SS组肉羊瘤胃总挥发性脂肪酸含量显著高于CS组（P<0.05）。3）SS组肉羊瘤胃内短普雷沃氏菌、栖普雷沃氏菌、产琥珀酸丝状杆菌和黄色瘤胃球菌的表达量显著高于CS组（P<0.05）。4）饲粮处理显著影响前胃颜色,CS组肉羊的前胃上皮颜色比SS组深（P<0.05）。5）SS组肉羊瘤胃乳头宽度显著高于CS组（P<0.05）,饲喂甜高粱青贮和玉米青贮对肉羊网胃黏膜厚度、黏膜下层厚度和肌层厚度并未产生显著影响（P>0.05）,CS组肉羊的瓣胃黏膜上皮厚度显著高于SS组（P<0.05）。综上所述,在本试验条件下,和饲用玉米青贮相比,饲用甜高粱青贮肉羊的采食量较低,且这两种青贮料饲喂对肉羊的微生态有影响,甜高粱青贮组肉羊的瘤胃总挥发性脂肪酸含量、前胃内纤维分解菌的表达量以及瘤胃乳头宽度等指标显著高于玉米青贮组,且甜高粱青贮组肉羊的前胃上皮颜色较浅,角质化程度低,有利于肉羊的胃肠道健康。     

饲用高粱青贮的饲喂价值和经济效益分析

高粱生物产量高、抗逆和适应性强,将其制作成青贮饲料,干物质产量、蛋白质含量、有氧稳定性高.草食家畜养殖是节粮型畜牧业的代表.采用高粱青贮饲喂草食家畜,不仅可以提高生产性能、增强免疫力、改善胴体品质,而且可以缓解冬季青贮饲料资源缺乏的问题,提高经济效益.为促进草食家畜养殖业健康稳定发展,文章对饲用高粱青贮的饲喂价值和经济...     

有机肥施用量对饲用高梁青贮品质的影响

摘要：采用田间试验研究有机肥（基肥）施用量对饲用高粱（Sorghum bicolor）青贮饲料品质的影响。结果表明,在施氮量相等的条件下,随着有机肥施用量的增加,青贮饲料的发酵品质先增高后下降,施用量以75和150 t/hm2为最好;同时,青贮饲料的酸性洗涤纤维和中性洗涤纤维含量不断增加,粗蛋白含量和干物质体外消化率不断下降。综合青贮饲料的发酵品质和饲用品质,饲用高粱青贮利用栽培时,施用有机肥基肥75～150 t/hm2较适宜。     

Comparative analysis of ensiling characteristics and protein degradation of alfalfa silage prepared with corn or sweet sorghum in semiarid region of Inner Mongolia

This study was conducted to evaluate silage fermentation and protein degradation of alfalfa prepared with corn or sweet sorghum (SS) at different mixing ratios. The chemical composition, ensiling characteristics, and protein degradation of alfalfa prepared with and without corn or SS at mixing ratios of 7:3, 1:1, and 3:7 on a fresh matter (FM) basis were studied. The alfalfa had the highest crude protein (CP) content and lactate buffering capacity (LBC), but lower water‐soluble carbohydrate (WSC) content than corn and SS. After 60 days of ensiling, the corn and SS silages had good quality, with lower pH and ammonia‐N content, and higher dry matter (DM) content than the alfalfa silages. In the alfalfa and corn mixture silages, the DM contents linearly increased with an increase in the proportion of corn, while the pH, non‐protein N (NPN), ammonia‐N, and peptide‐N contents linearly decreased. In the alfalfa and SS mixture silages, the DM and NPN contents linearly increased with an increase in the proportion of SS, while the pH, lactic acid, and ammonia‐N contents linearly decreased. This study suggests that alfalfa silage prepared with corn has more positive effect on fermentation quality and inhibiting protein degradation than addition of SS.     

Adding sweet potato vines improve the quality of rice straw silage

Rice straw and sweet potato vines are the main by‐products of agricultural crops, and their disposal creates problems for the environment in the south of China. In order to establish an easy method for making rice straw silage successfully, experiments were conduct to evaluate fermentation quality and nutritive value of rice straw silages ensiled with or without sweet potato vine. Paddy rice straw (PR) and upland rice straw (UP) were ensiled alone or with sweet potato vines (SP) by a ratio of 1:1 (fresh matter basis), over 3 years. Compared with rice straw silages ensiled alone, the mixed‐material silages (PR + SP, UR + SP) showed higher fermentation quality with lower propionic acid content and NH₃‐N ratio of total N, and higher (P < 0.05) concentrations of lactic acid and acetic acid, resulting in decrease (P < 0.05) of dry matter loss and higher (P < 0.05) in vitro ruminal dry matter digestion. When the fermentation quality, chemical composition and in vitro rumen fermentation characteristics were considered, ensiling would be an effective way of utilization of rice straw and sweet potato vines in the regions where rice and sweet potato are harvested at same season, and the sweet potato vines have the potential to improve rice straw fermentation quality with low water soluble carbohydrate content in south of China.     

甜高粱凋萎青贮料在肉兔全混日粮中适宜添加量的研究

采用蜡熟期甜高粱进行不同时间的凋萎处理,并进行青贮,分析了甜高粱饲用品质和青贮发酵品质的变化,明确甜高粱在凋萎过程中的养分动态以及适宜青贮加工的时间。结果表明凋萎5 h,甜高粱含水量(59.70%)和WSC含量(8.60%)是青贮品质最优。选择凋萎5 h的甜高粱青贮料进行不同添加量(添加量为25%,30%,35%)的肉兔饲喂试验,将不同添加量的青贮料配制成肉兔的全价混合日粮(total mixed ration,TMR)颗粒料进行饲喂。测定肉兔的每周增重,试验结束后进行生化指标分析。结果表明青贮甜高粱在TMR中的添加量从25%增加到35%,饲养5周后肉兔的总增重从871.56 g增加到950.25 g,而TMR颗粒料中青贮甜高粱添加30%~35%时,肉兔血液中谷丙转氨酶、谷草转氨酶、碱性磷酸酶、乳酸脱氢酶4种酶的活性均低于对照组,表明在全混日粮中添加30%~35%的凋萎青贮甜高粱有利于肉兔生长。     

青贮处理对两品种甜高粱营养成分及瘤胃降解率的影响

试验旨在研究青贮处理对两种甜高粱营养成分及瘤胃降解率的影响.选取3头装有永久性瘤胃瘘管的荷斯坦阉牛,采用尼龙袋法对甜高粱青贮前和青贮后的营养成分及瘤胃降解特率进行评定.结果 表明,青贮前,巨能甜高粱的粗蛋白(CP)含量显著高于大龙甜高粱(P＜0.05),非蛋白氮(NPN)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)...     

不同乳酸菌添加量和发酵时间对全株玉米青贮营养价值及发酵品质的影响

本试验以登海605玉米品种为材料,于蜡熟期2/3乳线时进行刈割,乳酸菌制剂的添加量分别为0,10,20和30 mg·kg^-1,4个处理,每个处理4个重复,在室温条件下发酵45和90 d,取样测定营养成分、发酵品质和瘤胃降解率等指标,旨在研究不同乳酸菌添加量和发酵时间对全株玉米青贮营养价值的影响。结果表明:干物质(DM)受乳酸菌添加量和发酵时间的影响较小,差异不显著(P>0.05);随乳酸菌添加量的增加,发酵90 d的中性洗涤纤维(NDF)含量显著线性降低(P=0.018),而相对饲喂价值(RFV)显著线性增加(P=0.006)。发酵90 d的酸性洗涤纤维(ADF)含量和pH值较45 d显著降低(P<0.01),而乳酸和乙酸含量显著增加(P<0.05)。随乳酸菌添加量的增加,乳酸含量显著线性增加(P<0.05)。24 h的DM和NDF消化率受乳酸菌添加量和发酵时间的影响较小,差异不显著(P>0.05)。发酵90 d时,48 h DM降解率随乳酸菌添加量的增加显著线性增加(P=0.034),48 h NDF降解率较45 d显著增加(P=0.022)。发酵90 d时,20 mg·kg^-1组的RFV、总可消化养分(TDN)和有机酸含量最高,而pH值最低。综上所述,乳酸菌添加量和发酵时间对全株玉米青贮的营养成分含量、发酵品质和DM瘤胃降解率均有显著影响,全株玉米青贮在发酵90 d且乳酸菌添加量为20 mg·kg^-1的营养价值和发酵品质最优。     

甜高粱饲草及葡萄籽对小尾寒羊生产性能及血液生理参数的影响

通过测定不同类型甜高粱饲草与葡萄籽饲喂小尾寒羊的生产性能和血常规,为甜高粱饲草和葡萄籽安全高效的饲喂绵羊提供理论依据。试验选取甘肃省定西市的小尾寒羊28只(17.30±1.20) kg,随机分为4组,分别为:饲喂甜高粱青贮+精补料(SN组)、甜高粱青贮+6%葡萄籽精补料(SY组)、甜高粱干草+精补料(DN组)、甜高粱干草+6%葡萄籽精补料(DY组)。分别在饲养试验的第1、30、60和100天晨饲前称重;第20、50和100天晨饲前采集血液,测定血常规。结果表明:甜高粱饲草与葡萄籽的添加对小尾寒羊平均干物质采食量、平均日增重和料重比影响不显著(P>0.05),但SY组比DN组平均日增重增加30%以上,终体重增加15.4%。葡萄籽的添加对小尾寒羊血液生理参数影响不显著(P>0.05)。甜高粱青贮组(SN+SY)小尾寒羊红细胞数目(RBC)和红细胞压积(HCT)显著高于甜高粱干草组(DN+DY)(P<0.05)。甜高粱青贮组(SN+SY)平均红细胞血红蛋白含量(MCH)和平均红细胞血红蛋白浓度(MCHC)极显著低于甜高粱干草组(DN+DY)(P<0.01)。试验第20和100天甜高粱青贮组(SN+SY)小尾寒羊血小板数目(PLT)显著低于甜高粱干草组(DN+DY)(P<0.05)。试验动物血液生理参数均在安全生产范围内,但饲喂甜高粱青贮对小尾寒羊红细胞和血小板相关指标更有利,且甜高粱青贮和葡萄籽结合饲喂对小尾寒羊生长性能有改善的潜力。     

Influences of Northern Leaf Blight on corn silage fermentation quality,nutritive value and feed intake by sheep

This study examined the differences between non‐inoculated (control) corn and Northern Leaf Blight (NLB)‐damaged corn (inoculated corn); dry matter (DM) yield, silage fermentation quality, nutritive value and feed intake by sheep were compared. Leaf, stem and grain dry weights and gross yield of inoculated corn were significantly (P < 0.05) decreased compared with control corn. The contents of water‐soluble carbohydrate and nitrogen‐free extract (NFE) were decreased in inoculated corn compared with control corn. Silage made from both inoculated and control corn showed good fermentation quality. The digestibility of DM, organic matter, ether extract, NFE, and energy of silage made from inoculated corn were significantly (P < 0.05) lower, and contents of total digestible nutrients (TDN) and digestible energy (DE) were also significantly (P < 0.05) lower compared with silage made from the control corn. DM intake showed no significant discrepancy between the two types of silage. TDN and DE intakes from inoculated silage were significantly (P < 0.05) lower compared with control silage. From the above results it was shown that NLB caused a decrease in DM yield and NFE content in corn and a decrease in the nutritive value and feed intake of silage.     

Effect of grape pomace on fermentation quality and aerobic stability of sweet sorghum silage

The objective of this study was to evaluate the effect of grape pomace (GP) with different adding levels (0%, 5%, 10% and 15%, fresh matter basis), alone (GP‐LAB) or in combine with an inoculant LAB (GP+LAB), on the fermentation quality and aerobic stability of sweet sorghum silage. After 90 days of ensiling in vacuumized mini‐silos, silages were subject to a 7‐day aerobic stability test, in which chemical, microbial and polyphenol composition were measured. In the GP‐LAB group, adding GP decreased (P < 0.05) concentrations of water‐soluble carbohydrate (WSC) and butyric acid in silage. In the GP+LAB group, adding GP increased (P < 0.05) concentrations of lactic acid, WSC and crude protein, decreased (P < 0.05) final pH value, NH₃‐N ratio and butyric acid concentration in silage. Polyphenol level was reduced (P < 0.05) after silage fermentation. During aerobic exposure, the fungi count, pH value and silage temperature increased (P < 0.05), the levels of lactic acid, acetic acid and polyphenols (quercetin 3‐O‐glucoside and quercetin 3‐O‐glucuronid) decreased (P < 0.05) in silage. GP+LAB treated silage had a lag phase for aerobic spoilage. When the fermentation products, microbial counts, chemical and polyphenol composition were considered, the use of 10% GP+LAB at ensiling could provide a valuable source for improved fermentation quality and aerobic stability of sweet sorghum silage.     

甜高粱的饲用价值及其绵羊体外瘤胃发酵产气性能研究

本试验旨在研究不同收割时期饲用甜高粱的饲用价值及其绵羊体外瘤胃发酵产气性能,分别对8-11月收割的甜高粱(大奖3180,标记为S₁、S₂、S₃与S₄)的养分含量及相对饲喂价值(RFV)、总可消化养分(TDN)、干物质采食量(DMI)、可消化干物质(DDM)和牧草相对饲用品质(RFQ)进行评价。利用体外模拟发酵产气技术评定不同收割时期的甜高粱在3、6、9、12、24、36和48 h体外产气规律,估算降解率。结果表明,1)不同收割时期的甜高粱的干物质(DM)、粗蛋白(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、粗脂肪(EE)和粗灰分(Ash)含量差异均显著(P<0.05)。2)不同收割时期的甜高粱的RFV、DMI、RFQ呈现出S₁>S₄>S₃>S₂,差异极显著(P<0.001)。S₁和S₄的TDN和DDM含量差异不显著(P>0.05),但极显著高于S₂和S₃(P<0.001)。3)在培养12 h之前,不同收割时期的甜高粱产气量(GP)差异极显著(P<0.001),且S₃的GP最高;24 h后,S₄的GP显著高于S₂(P<0.05);培养36 h后不同收割时期的甜高粱GP差异不显著(P>0.05)。4)不同时期收割的甜高粱在发酵12、24、48 h的干物质消失率(DMD)均无显著差异(P>0.05)。综上结果,8月对黄土高原丘陵沟壑区甜高粱进行收割时饲用价值最好。     

混贮模式对高丹草青贮发酵品质及体外产气动力学特性的影响

为了解决高丹草因水分高造成青贮发酵品质不佳的问题,通过添加不同种类干草(玉米秸秆、小麦秸秆和苜蓿干草)及干草添加量(12.5,25.0,37.5和50.0kg/t)对混贮高丹草营养价值、青贮发酵品质及体外产气动力学特性进行了研究。结果表明,单独青贮高丹草的丁酸含量较高,弗氏评分等级仅为"可",添加干草混贮可显著提高青贮高丹草的发酵品质,从添加干草的种类来看,添加小麦秸秆组青贮发酵品质最高,添加苜蓿干草组营养价值最高,苜蓿干草组的体外72h干物质消失率(IVDMD)、产气速率(c)和达到最大产气量1/2时的产气速率(AGPR)均为最高,3种干草在72h累积产气量、理论最大产气量以及产气延滞时期方面差异不显著(P0.05);从干草的添加量来看,添加25.0kg/t干草的青贮发酵品质最优,达到产气量1/2所需要时间也最长,添加50.0kg/t干草的营养价值和IVDMD最高,添加37.5kg/t干草的产气速率和AGPR最大,添加不同重量干草对混贮高丹草的72h累积产气量、理论最大产气量以及产气延滞时期无显著影响(P0.05)。综合考虑青贮发酵品质和饲料营养价值,得出最佳的混贮模式为在高丹草中添加37.5kg/t小麦秸秆,添加50.0kg/t苜蓿干草混贮高丹草的体外干物质消失率最高,添加37.5kg/t苜蓿干草组产气速率最快,添加50.0kg/t小麦秸秆组的72h累积产气量和理论最大产气量最高。     

同/异型发酵乳酸菌对全株玉米青贮营养成分和瘤胃降解特征的影响

以新饲玉10号全株青贮玉米为研究材料,旨在探究同/异型发酵乳酸菌对其主要营养成分和瘤胃降解率特征的影响。采用真空袋法调制青贮,共设计4个发酵处理,分别为不添加任何菌剂(CK);复合同型发酵乳酸菌植物乳杆菌+戊糖片球菌(T),添加量为1∶1,1×10^5 cfu·g^-1;异型发酵乳酸菌布氏乳杆菌(Y),添加量为1×10^5 cfu·g^-1;复合同、异型发酵乳酸菌(TY),添加量为1∶1∶1,1×10^5 cfu·g^-1。通过对模拟开窖60 d主要营养成分和绵羊瘤胃降解特征参数的分析。结果表明:干物质(DM)、中/酸性洗涤纤维(N/ADF)、可溶性碳水化合物和粗脂肪含量最优均为Y处理,粗蛋白和淀粉含量各试验处理均极显著高于CK处理(P<0.01),粗灰分含量最高为CK处理。DM和NDF有效降解率按高低排序均为T和Y处理>CK和TY处理(P<0.01)。有机物(OM)有效降解率最高为Y处理(P=0.003)。各处理ADF有效降解率间差异不显著(P>0.05)。说明玉米青贮中Y处理可显著增加开窖60 d时各营养成分含量(粗灰分除外),且显著提高DM和OM有效降解率,TY处理可显著提高NDF有效降解率。综合营养成分和有效降解率12项指标进行隶属函数评价,各处理按优劣排序为:Y处理>T处理>TY处理>CK处理。     

Evaluation of feeding value of forage soybean silage as a substitute for wheat bran in sheep

Twelve sheep were used in a 3 × 3 Latin square design to evaluate the effect of substituting wheat bran with forage soybean silage in the diet on apparent digestibility and nitrogen balance. Forage soybean (Glycine max (L.) Merrill) was cultivated in a no‐till, no‐herbicide cropping system with Italian ryegrass (Lolium multiflorum Lam.) as a living mulch. Forage soybean and Italian ryegrass were wilted and ensiled in round bales without additives, respectively. The experimental diets were based on corn silage supplemented with protein sources (tow silages or wheat bran). The crude protein and the acid detergent insoluble protein contents of forage soybean silage were the highest among the protein sources. The apparent digestibility of crude protein and the nitrogen balance did not significantly differ among the diets. In addition, the phytoestrogen content of forage soybean silage was below the level at which animal reproductive performance would be negatively affected. These results suggest that forage soybean silage has comparable feeding value to wheat bran, and can be given at an inclusion level of 17% (dry matter basis) as an alternative protein source to wheat bran without adverse effects on digestion or nitrogen balance in sheep fed a corn silage‐based diet.     

The effects of urea‐treated potato pulp (PP) ensiled with beet pulp or wheat bran pellets to reduce moisture of PP and flake density of corn grain supplemented with the PP silage on digestibility and ruminal fermentation in beef steers

The effects of adding beet pulp or wheat bran to urea‐treated potato pulp (PP) in order to reduce moisture of PP silage and flake density of corn grain on digestibility and ruminal fermentation in beef steers were studied in a split‐plot design experiment. The whole‐plot treatments were PP silage mixed with 0% added pellets (CON), 9% (as‐fed basis) beet pulp pellets (BP) or 9% (as‐fed basis) wheat bran pellets (WB) as water‐absorbing materials. The subplot treatments consisted of supplements formulated to contain either high‐density corn (HDC) or low‐density corn (LDC). BP steers consumed more (BP vs WB, P = 0.011) concentrate than did WB steers, whereas hay intake did not differ between the treatments. Dry matter (BP vs WB, P = 0.023) and organic matter (BP vs WB, P = 0.029) digestibility were higher for BP steers than for WB steers. Starch digestibility was higher (P = 0.006) for LDC than for HDC. There were no differences in the concentration of ruminal ammonia nitrogen among the treatments. Molar proportions of ruminal acetate were higher for BP steers than for WB steers (BP vs WB, P = 0.030). Conversely, molar proportions of propionate were lower for BP steers than for WB steers (BP vs WB, P = 0.044). Flake density of corn did not affect ruminal characteristics. In conclusion, from the viewpoint of feed intake and digestibility, BP is superior to WB as a moisture control material for urea‐treated PP silage, and flake density of corn supplemented with urea‐treated PP silage does not alter ruminal fermentation.     

Characterization and application of lactic acid bacteria for tropical silage preparation

Strains TH 14, TH 21 and TH 64 were isolated from tropical silages, namely corn stover, sugar cane top and rice straw, respectively, prepared in Thailand. These strains were selected by low pH growth range and high lactic acid‐producing ability, similar to some commercial inoculants. Based on the analysis of 16S ribosomal RNA gene sequence and DNA‐DNA relatedness, strain TH 14 was identified as Lactobacillus casei, and strains TH 21 and TH 64 were identified as L. plantarum. Strains TH 14, TH 21, TH 64 and two commercial inoculants, CH (L. plantarum) and SN (L. rhamnosus), were used as additives to fresh and wilted purple Guinea and sorghum silages prepared using a small‐scale fermentation method. The number of epiphytic lactic acid bacteria (LAB) in the forages before ensilage was relatively low but the numbers of coliform and aerobic bacteria were higher. Sorghum silages at 30 days of fermentation were all well preserved with low pH (3.56) and high lactic acid production (72.86 g/kg dry matter). Purple Guinea silage inoculated with LAB exhibited reduced count levels of aerobic and coliform bacteria, lower pH, butyric acid and ammonia nitrogen and increased lactic acid concentration, compared with the control. Strain TH 14 more effectively improved lactic acid production compared with inoculants and other strains. © 2016 Japanese Society of Animal Science     

Effects of feeding pistachio by‐products silage on growth performance,serum metabolites and urine characteristics in Holstein male calves

This study investigated physiological effects of pistachio by‐products silage (PBPS) substituted in Holstein male calves diets and its effects on the growth performance. Twenty‐four Holstein male calves (4–5 months of age and 155.6 ± 13.5 kg BW) were randomly assigned to one of four experimental diets (n = 6); contained 0%, 6%, 12% and 18% of PBPS (DM basis) respectively. During a 6‐month experiment, dry matter intake (DMI) and weight gain were recorded and blood and urine samples were collected at different times. Results showed that mean DMI was not affected by different levels of PBPS in diets. But the calves fed 6% PBPS had the highest average daily gain (p < 0.05) and the lowest feed conversion ratio (p < 0.05). The calves fed 12% and 18% PBPS had lower albumin, white blood cell, haemoglobin and packed cell volume (p < 0.05) than those fed other diets. However, other serum metabolites, complete blood count (CBC), insulin and liver enzymes were not affected by the experimental diets. The long‐term feeding of PBPS at different levels had no significant effect (p > 0.05) on pH, specific gravity, the number of white and red blood cells and epithelial cells count in urine. The animals did not show any symptom of illness or toxicity during the experimental period and all of the blood and urine parameters were in a normal range. It was concluded that substitution of PBPS up to 18% of the total diet that provide up to 18.2 g/kg DM total tannin had no adverse effects for Holstein male calves.     

The effects of protein sources supplemented with urea-treated potato pulp (PP) silage and feeding levels of the PP silage-based concentrate on feed intake, digestibility and ruminal fermentation in beef steers

Six Japanese Black (Wagyu) steers (average initial weight 467 ± 45 kg) fitted with a ruminal cannula were used in a split‐plot design experiment comprising a 3 × 3 Latin square design (whole‐plot) and a randomized block design (subplot). The whole‐plot treatments were three different feeding levels of urea‐treated potato pulp (PP) silage‐based concentrate: 1.00%, 1.75% and 2.50% of body weight (BW) (on a dry matter (DM) basis). The subplot treatments consisted of the concentrate formulated to contain either soybean meal (SBM) as a rapidly rumen‐degraded protein source or corn gluten meal (CGM) as a slowly degraded protein source. Dry matter intake tended to be lower (P = 0.071) for CGM (8.9 kg/day) than for SBM (9.4 kg/day). Protein sources had no significant effect on digestibility and in situ degradation. Ruminal ammonia nitrogen (NH₃‐N) was lower (P = 0.033) for CGM (7.5 mg/dL) than for SBM (9.5 mg/dL). Protein sources did not affect ruminal pH and the total volatile fatty acids (VFA) concentrations. The molar proportions of ruminal acetate and valerate were higher (P = 0.032) for CGM than for SBM. The maximum daily intake of the PP silage‐based concentrate expressed as a percentage of BW was approximately 1.4% of BW. Dry matter intake was higher (P = 0.046) for steers fed at 1.0% of BW of the PP silage‐based concentrate than for steers fed at 1.75% or 2.5% of BW of the concentrate. The feeding levels of the PP silage‐based concentrate had no effect on DM and nutrients digestibility, except for crude protein (CP) digestibility. CP digestibility tended to be lower (P = 0.071) for steers fed at 1.75% of BW of the PP silage‐based concentrate than for steers fed at 1.0% or 2.5% of BW of the concentrate. The feeding levels of the PP silage‐based concentrate also did not affect the in situ degradation parameter of hay and PP silage. The feeding levels of the PP silage‐based concentrate did not affect ruminal pH, NH₃‐N and total VFA concentrations. The molar proportion of acetate was highest for steers fed at 1.0% of BW of the concentrate. In conclusion, in the urea‐treated PP silage‐based concentrate, CGM seems to be more effective than SBM for stabilizing the ruminal NH₃‐N concentration and to be advantageous for fiber digestion in the rumen. The feeding levels of the PP silage‐based concentrate did not change the amount of VFA production in the rumen and the DM digestibility.