Effects of planting density and processing method on laboratory characteristics of grain sorghum for ruminants

Grain sorghum grown in 38-cm (high-density) or 76-cm rows (normal-density) was steam-flaked, harvested as high-moisture grain followed by rolling and ensiling, or dry-rolled. Chemical composition, enzymatic starch availability, CP insolubility, and IVDMD in a reduced-strength buffer were evaluated. High-density planting increased (P < .10) OM and starch concentration and decreased (P < .0001) CP concentration but did not affect (P > .10) P concentration, enzymatic starch availability, or CP insolubility. High-density planting resulted in lower (P < .10) in vitro ruminal culture pH at 6, 12, and 18 h of incubation when grain sorghum was processed by steam flaking, and lower (P < .10) IVDMD at 6, 12, and 18 h of digestion when grain sorghum was processed by dry rolling. Steam flaking decreased (P < .10) CP concentration and solubility and increased (P < .10) OM concentration. High-moisture ensiling decreased (P < .10) the insolubility of CP but did not otherwise seem to alter the chemical composition of grain sorghum relative to dry rolling. Starch was more available (P < .10), and DM was digested more rapidly and extensively (P < .10) in vitro, in steam-flaked sorghum followed by high-moisture sorghum. Based on these data, it seems that planting density primarily affected chemical composition of grain sorghum, whereas processing primarily affected CP insolubility and rate and extent of starch fermentation.     

饲用甜高粱对绵羊体重和养分消化率的影响

本文采用单因素随机试验设计的方法,选择8月龄左右的道赛特母羊51只,随机分为3组,试验期为35d,研究饲用甜高梁对绵羊体重和能量、蛋白质及脂肪消化率的影响.各组精料相同,粗料中分别含有100%饲用甜高粱(A)、50%饲用甜高粱+50%青干草(B)和100%青干草(对照组).结果表明:试验A、B组绵羊的平均日增重和能量的消化率与对照组之间差异不显著(P＞0.05),而日粮中粗蛋白质的消化率显著低于对照组(P＜0.05).试验A组绵羊对日粮中粗脂肪的消化率显著高于对照组(P＜O.05).说明绵羊对饲用甜高粱粗蛋白质的利用率较低,实践中应限量饲用.     

Flake density of steam-processed sorghum grain alters performance and sites of digestibility by growing-finishing steers.

The effect of several flake densities (FD) of steam-processed sorghum grain on performance, and site and extent of nutrient digestibilities by steers fed growing and finishing diets was determined. The effectiveness of common laboratory methods of starch availability (enzymatic hydrolysis or gelatinization) to provide target specifications for quality control of steam-flaked grains was also measured. In vitro starch availability of the processed grains increased (P < .05) linearly in response to decreased FD. Flake density was more highly correlated with enzymatic measures than with percentage gelatinization (R2 = .87 to .93 vs .36). Using 140 crossbred beef steers (181 kg initial weight), feedlot performance was determined for 112 d with a growing diet (50% grain), followed by 119 d with a finishing diet (78% grain). Each FD treatment (412, 360, 309, and 257 g/L or 32, 28, 24, and 20 lb/bu) was randomly assigned to five pens of seven steers each. Intake of DM by steers decreased linearly (P < .05) as FD decreased (7 and 13%, respectively, for growing and finishing diets). Decreasing FD reduced linearly (P < .05) ADG in the finishing phase and for the entire 231-d trial. With the growing diet only, feed efficiency and estimated diet NEm and NEg responses to decreasing FD were curvilinear (P < .05), with the 360 g/L (28 lb/bu) flake being most efficient. Electrical energy requirements for processing increased linearly (P < .05) as FD decreased. Using four multi-cannulated crossbred steers (275 kg), starch digestibility increased linearly (P < .05) in the rumen (82 to 91%) and total tract (98.2 to 99.2%) as FD decreased. Digestibilities within the small (74%) and large intestines (62%) were not altered by FD. Decreasing FD increased (P < .05) total CP digestibility, but did not consistently alter fiber digestibility or DE content of the diets. In conclusion, enzymatic laboratory methods to evaluate starch availability in processed grains can be used satisfactorily to establish FD criteria for quality control of the steam-flaking process. The greatest improvements in efficiency, estimated diet NE, and starch and protein digestibilities usually occurred when FD was decreased from 412 to 360 g/L (32 to 28 lb/bu). Based on these measures and processing costs, the optimal FD was 360 g/L (28 lb/bu).     

Recent information on processing of grain for ruminants

When excessively processed cereals are given to ruminants a vast surface area of highly fermentable substrate is exposed to the rumen microorganisms. The subsequent effect on digestion and metabolism will depend largely on whether the cereal based diets are fed as the main or sole part of the diet or whether they are given as supplements to roughage based diets.Given as sole feeds, excessively processed grains can give rise to alterations in carcass quality (soft fat) in lambs, and problems of acidosis and rumenitis.Given as supplements to diets based on roughage, excessively processed grains can seriously reduce the rate of cellulose digestion with a consequent decrease in roughage intake and digestibility.The optimum extent of processing appears to be the minimum required to avoid an unacceptably low digestibility. The processing required is different for small ruminants (e.g. sheep, goats and calves) than for large (e.g. cattle).For sheep, grain should be fed whole; in general, processing does not increase digestibility or food utilization and can result in depressed cellulose digestion and in soft fat.For cattle some processing is required to ensure adequate digestion but the optimum is that required to give entrance through the seed coats to microorganisms and digestive enzymes. New methods, such as chemical treatment of whole grain, have given promising results.     

种植密度和品种对青饲玉米生物量与营养品质的影响

通过研究种植密度和品种对青饲玉米(Zea mays)生物量与营养品质的影响,筛选出适宜环县地区的较优青饲玉米品种及种植密度,以期为该区优质青饲玉米的推广种植及牛羊青粗饲草料资源的开发提供理论依据.试验于2019年选用'东单13'(H1)、'正大12'(H2)、'科玉188'(H3)、'衡远4038'(H4)及'濮单6号'(H5)5个青饲玉米品种为试验材料,每个品种分别设4.50×104(D1)、5.25×104(D2)、6.00×104(D3)、6.75×104(D4)及7.50×104(D5)株·hm?25个种植密度,结果表明,种植密度对鲜草产量和干草产量的影响极显著(P<0.01),对粗灰分(Ash)含量的影响显著(P<0.05).品种对粗脂肪(EE)、Ash、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、淀粉(ST)、钙(Ca)、磷(P)和总可消化养分(TDN)含量及48 h干物质体外消化率(IVDMD)的影响极显著(P<0.01),对干物质(DM)、水溶性碳水化合物(WSC)含量的影响显著(P<0.05).用灰色关联度对各处理生物量和营养品质指标综合评价后,结果排名前三的品种及密度依次为H1D5>H2D4>H3D5.综上,在环县地区表现较优、排名前三的青饲玉米品种及其密度分别为7.50万株·hm?2的'东单13'、6.75万株·hm?2的'正大12'及7.50万株·hm?2的'科玉188',可在该地区推广种植.     

Improved enzymatic method to measure processing effects and starch availability in sorghum grain

A modified enzymatic method to measure processing effects and starch availability in steam-flaked sorghum grain (SFSG) was developed. To establish the method, experiments were conducted to determine the required enzyme concentration, color reagents, precipitants, sample particle size, shaking frequency and buffer pH. Glucose release at different incubation times (0 to 48 h) from uncooked (UNC) or fully cooked (CK, 100% gelatinized) ground sorghum grain, a 50:50 mixture of UNC and CK (C50) and SFSG was determined. Glucose release from UNC, CK and SFSG was expressed as one-component equations with rate constant k and r2 of .119 and .98, 1.781 and .98, and .368 and .99, respectively; C50 was characterized by having two starch components, one with a fast rate constant, 2.624/h, and one with a slow rate constant, .066/h (R2 = .99). Different degrees of gelatinization were obtained by mixing different proportions of CK and UNC. Glucose release from these samples was highly correlated with starch gelatinization (r2 = .99). By adjusting the tension between mill rollers, five SFSG samples with bulk densities ranging from 476 to 283 g/liter (37 to 22 lb/bu) were produced; respective roller mill electrical load ranged from 21 to 51.5 amps. Enzymatic determination of glucose release resulted in values of 422, 512, 588, 618 and 678 mg/g, which were more closely related to bulk density than birefringence measurements. The modified method for starch availability determination was found to be relatively simple, fast and sensitive, and is recommended.     

Effect of grain processing and silage on microbial protein synthesis and nutrient digestibility in beef cattle fed barley-based diets

Effects of the extent of grain processing and the percentage of silage in barley-based feedlot diets on microbial protein synthesis and nutrient digestibility were evaluated using four steers (initial BW of 442 +/- 15 kg) with ruminal and duodenal cannulas. The experiment was a 4 x 4 Latin square with four periods of 21 d each. Dietary treatments were arranged as a 2 x 2 factorial with two levels of barley silage (20 and 5% DM basis) and two degrees of barley grain processing (coarsely and flatly steamrolled to a processing index [PI] of 86 and 61%, respectively). The PI was quantified as the volume weight of the barley grain after processing, expressed as a percentage of the volume weight prior to processing. Digest a flow (Yb) and microbial (15N) markers were continuously infused into the rumen for a period of 13 d. Ruminal, duodenal, and fecal samples were collected at various times over the last 6 d of marker infusion. Diurnal ruminal pH was measured for 48 h. Intake of DM averaged 1.8% of BW, and was not different among the dietary treatments (P > 0.10). Ruminal starch digestibility was higher (P < 0.05) for the more extensively processed grain and tended (P < 0.10) to be highest when the more extensively processed grain was combined with 5% barley silage. In contrast, ruminal fiber digestibility for the 5% silage diets was reduced (P < 0.05) when the grain was more extensively processed. There was, however, no effect of grain processing on ruminal OM digestibility (P > 0.10), and hence, no inhibitory effect on microbial N flow to the intestine (P > 0.10). There was also no effect of the level of silage on microbial N flow (P > 0.10), but there was a tendency for improved efficiency of microbial protein synthesis for the 20% silage diets (P = 0.072). Ruminal escape of nonmicrobial N (P = 0.003) was greater, and thus, protein flow to the intestine was greater for the 5% silage diets. Diurnal ruminal pH was lower (P < 0.05) for 11 of the 24 hourly time points in steers fed the 5% silage diets than those fed the 20% silage diets. In conclusion, barley grain rolled to a PI of 86 to 61% and combined with 20 and 5% barley silage had little effect on microbial protein supply. Microbial protein supply was not inhibited when the barley grain was extensively processed (PI of 61%) and the silage was limited to only 5% of the diet DM, but feed intake of steers in this study was lower than would be expected in the feedlot.     

Effects of different heat treatments during processing on nutrient digestibility of soybean meal in growing swine

Four soybean meals (SBM) were prepared in a commercial solvent-extraction plant to give a much wider range in heat treatment than is usually found among commercially available SBM. The meals were designated in ascending order of heat treatment as Under, Normal, Over and Rumen Escape. The Normal meal was processed using standard operating conditions. The Under meal received less heat treatment by reducing the steam pressure and retention time in the desolventizer-toaster. Over and Rumen Escape meals received further heat treatment in an additional four-compartment toaster. The Over meal received less heat treatment than the Rumen Escape meal by reducing steam pressure and retention time in both toasters. Crude protein content was similar for the four meals, but lysine tended to decrease with increasing heat treatment. In general, urease activity, trypsin inhibitor, protein dispersibility index and nitrogen solubility index decreased with increasing heat treatment. The +a Hunterlab color values increased as heat treatment increased. Apparent ileal digestibility of N and amino acids were similar for all meals (P greater than .05); however lysine digestibility for the Rumen Escape meal was 3.3 percentage units lower than the average of the lesser-heated meals. Energy digestibilities and nitrogen balance data were also similar (P greater than .05) for the four meals, but the apparent biological value of the Rumen Escape meal was 4.5 percentage units lower than the average of the other meals. There were no differences in nutritional value among the Under, Normal and Over meals, which represent the range in heat treatment usually found among SBM. The Rumen Escape meal, which received more severe heat treatment, tended to have lower nutritional value than the lesser-heated meals.     

高粱的加工、粒度和水分对饲料制粒和肉鸡生长性能的影响

本研究旨在评价不同水分和颗粒粒度的高粱制粒或膨化对不同原料粒度、肉鸡代谢能、氨基酸回肠消化率和肉鸡生长性能的影响。试验以720只雄性雏鸡为研究对象,随机分为6组,每组6个重复,每个重复20只。试验处理以2×2×2因子设计,即2种加工方式(制粒和膨化),2个调质水分(1.6%和0.8%),2个颗粒粉碎粒度(650和850μm)。结果显示:在添加1.6%水分的膨化日粮中,制粒制粒和颗粒耐久指数较高。850μm的粒径增加了饲料颗粒耐久指数。各处理组对肉鸡日增重和屠体性状均无显著影响(P>0.05)。在10~13 d饲喂颗粒饲料和添加1.6%水分的饲料的肉鸡表观代谢能和氮校正代谢能均较高(P<0.05),与添加膨化性饲料相比,高粱制粒饲料回肠赖氨酸和甘氨酸消化系数显著提高(P<0.05)。在评价饲料加湿效果时,饲料添加1.6%水分后赖氨酸、蛋氨酸、胱氨酸、甘氨酸、组氨酸、异亮氨酸和精氨酸回肠表观消化系数显著升高(P<0.05)。1.6%水分的膨化饲料较0.8%水分显著提高了21 d肉鸡采食量(P<0.05),在42 d时,0.8%水分的颗粒饲料显著提高了采食量(P<0.05)。结论:以650μm的粉碎粒度和1.6%的水分制备颗粒饲料在肉鸡生长后期可以提高回肠氨基酸消化率和表观代谢能,而膨化工艺提高了42 d肉鸡饲料颗粒制粒和饲料转化率。     

Effect of grain processing on in sacco digestibility and degradability in the rumen

Effect on nylon-bag digestibility of rolling and steam-flaking as such or followed by grinding through a 1-mm screen was studied in wheat, barley and maize grains. Digestibilities of ground grains were not different, irrespective of rolling or steam-flaking, except flaked and ground barley, which was less digestible than ground barley. Rolled and flaked grains were less digestible than ground grains, except for rolled wheat which was not different from ground wheat. These results suggest that particle size due to grinding is more important than other methods of processing. Dry matter and protein degradabilities of steam-flaked grains were investigated by in sacco technique and compared with unprocessed grains. Dry matter degradability during incubation periods up to 24 h was reduced for steam-flaked wheat and barley, but increased for flaked maize. Protein degradability was lower for flaked grains.     

Effect of grain sorghum hybrid on in vitro rate of starch disappearance and finishing performance of ruminants.

Forty-eight commercial grain sorghum hybrids were ranked on the basis of in vitro starch disappearance (IVSD) and starch content. Starch content ranged from 64.3 to 70.3% (P less than .01) and IVSD ranged from 5.2 to 6.3%/h (P less than .01). In the next year, 20 experimental grain sorghum hybrids consisting of 17 hybrids being developed for livestock diets and three for human diets were ranked according to IVSD, starch content, and CP content. In these samples, IVSD varied from 6.0 to 9.1%/h (P less than .05). Starch content and CP were not related to IVSD. Starch content was not correlated to CP content. Four of the original 48 grain sorghum hybrids, selected on the basis of IVSD (two fast and two slow), that differed in IVSD by 7.0% (6.5 to 7.0%/h), were fed for 133 d to steers (mean initial BW of 326 kg). The ADG of steers fed Hybrid A (fastest IVSD) was 9.0% faster than that of steers fed Hybrid D (slowest IVSD; 1.33 vs 1.22 kg, P = .06). Gain:feed ratio was positively correlated with IVSD across all treatments (R2 = .94). Hybrids A and D, another Hybrid, A1, and a bird-resistant hybrid (BR) were fed for 85 d to finishing lambs (mean initial BW of 28 kg). Lambs fed Hybrid A gained more efficiently (gain:feed) than those fed BR or A1 (.210 vs .188 and .184, P less than .05), and those fed D were intermediate (.200). Performance of sheep fed A1, with the fastest IVSD, and those fed BR, with the lowest IVSD, were similar, suggesting that factors other than IVSD affected lamb performance. Our data indicate that rate of grain sorghum starch digestion may influence feeding value of grain sorghum fed to cattle.     

大米替代玉米对断奶仔猪生产性能和营养物质消化率的影响

试验组日粮用大米替代玉米．分别添加3种不同淀粉糊化度的大米。结果表明：随着断奶仔猪日龄的增加．各处理组的营养物质表观消化率显著增加（P〈0．01）,大米营养物质的表观消化率显著大于玉米日粮。29日龄断奶仔猪饲喂热处理的大米可以提高营养物质的表观消化率．但是对39日龄和53日龄的仔猪无影响。改变加工条件．大米淀粉糊化度从52％增加到76％和米粒从480μm降低到405μm,没有进一步提高断奶仔猪消化率。25～53d．饲喂大米的断奶仔猪增加了仔猪采食量（P〈0．05）、ADG（P〈0．01）,并提高了G：F（P〈0．10）。25-39d．断奶仔猪饲喂大米组与玉米组相比,提高了仔猪采食量（P〈0．01）、ADG（P〈0．01）和G：F（P〈0．01）。饲喂大米可以提高断奶仔猪生产性能。温和热处理后的大米．提高了断奶仔猪生产性能和营养物质消化率。过热处理的大米．提高了大米淀粉糊化度．但是没有进一步提高断奶仔猪的生产性能和营养物质的消化率。     

箭筈豌豆种植密度对土壤微生物养分代谢的影响

箭筈豌豆是一种优良的绿肥作物,具有固氮、改善土壤结构等功能,在农业生产中使用十分普遍,但目前关于种植箭筈豌豆对土壤微生物养分代谢特征影响的研究还鲜有报道.本研究基于盆栽试验,设置了不同种植密度的箭筈豌豆处理,包括低密度组(19株·盆-1)与高密度组(40株·盆-1),同时设置空白土壤作为对照,研究上述处理对土壤养分和微生物特性的影响.结果显示:1)高密度组箭筈豌豆生物量和养分积累量均高于低密度组,从土壤获得的有效养分增加,植物生长受P的限制性增强;2)种植箭筈豌豆高密度组处理显著降低了土壤可溶性无机磷含量,尽管对可溶性有机碳和总氮的影响不显著,但可溶性总氮较对照明显有降低的趋势,最终对土壤可溶性养分计量比RC:N、RC:P、RN:P的影响不显著;3)种植箭筈豌豆增加了SMBC、SMBN含量和SMBC:SMBP、SMBN:SMBP,降低了SMBP含量和SMBC:SMBN,表明微生物生长对N的需求量增加;4)种植箭筈豌豆降低了土壤BG(C-获取酶)酶活性而增加了(NAG+LAP)(N-获取酶)和AP(P-获取酶)酶活性,降低了BG:(NAG+LAP)、BG:AP和(NAG+LAP):AP,表明土壤微生物通过增加N和P获取的酶活性以增加对短缺养分的获取.因此,种植不同密度的箭筈豌豆在改变土壤养分特征的同时,还改变了土壤微生物养分代谢特征,微生物通过调整体内养分含量及胞外酶的分泌量及计量比以适应新的资源供应特征.     

粗纤维水平对断奶新西兰兔营养物质消化率的影响

为了探讨断乳兔日粮适宜的粗纤维水平,选择36只30日龄体重差异不显著的断奶新西兰幼免,设3个水平,分别饲喂粗纤维含量为8%、10%、12%的日粮.每个水平3个重复,每个重复4只.结果表明:粗纤维含量为10%的试验兔日增重(28.59 g)最高,而12%组最低,但各组间差异不显著(P＞0.05).随粗纤维含量的增加,采食量呈上升趋势,3个组的日平均采食量分别为85.01、85.72、89.86 g/d.12%组中料肉比显著高于8%、10%组(P＜0.05).不同粗纤维饲粮的粗蛋白质、能量、总磷消化率差异均不显著(P＞0.05);10%水平组,粗纤维、粗脂肪消化率极显著高于12%(P＜0.01).而钙消化率显著高于12%(P＜0.05);粗脂肪、无氮浸出物显著高于8%(P＜0.05).本试验条件下.断乳免日粮适宜的粗纤维水平为10%.     

烟酸铬对西门塔尔牛日粮养分消化率的影响

试验选用4头体重(500±20)kg,年龄3.5岁,装有永久性瘤胃瘘管的西门塔尔牛阉牛,采用4×4拉丁方试验设计,以混合精料和风干玉米秸秆为基础日粮,研究日粮中添加烟酸铬(0、40、80、120 mg/d)对日粮养分消化率的影响。结果表明:日粮添加烟酸铬80 mg/d组的干物质(DM)、有机物质(OM)、粗脂肪(EE)、粗蛋白质(CP)、无氮浸出物(NFE)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的表观消化率较对照组显著提高(P<0.05)。因此在本试验条件下日粮中烟酸铬适宜添加水平为80 mg/d。     

奶牛日粮加锌对营养物质表观消化率的影响研究

选择8头泌乳前期的中国荷斯坦奶牛,采用4×4重复拉丁方设计,研究奶牛日粮加锌对营养物质全消化道表观消化率的影响。试验分为4组,每组2头,其中A为对照组(基础日粮);B组(基础日粮 20mg/kgZn);C组(基础日粮 40mg/kgZn);D组(基础日粮 60mg/kgZn),试验期分3个阶段,共3个月。结果表明:B组、C组和D组干物质、粗蛋白质、粗脂肪、酸性洗涤纤维和中性洗涤纤维的全消化道表观消化率均比A组有增强的趋势,但均差异不显著(p>0.05)。     

Effect of protein source and lasalocid on nitrogen digestibility and growth by ruminants

Protein supplements having either a high (soybean meal, SBM) or low (escape protein, EP) extent of ruminal N degradability with or without lasalocid (L) were evaluated in digestion and growth trials. The SBM supplement included soybean meal while EP was a combination of dehydrated alfalfa and distillers dried grains. Nitrogen digestibility of SBM supplements was consistently higher than EP supplements when evaluated with two lamb trials. Digestibility of N was improved 8% in trial one (64.9 vs 60.3%) and 27% in trial two (66.3 vs 52.3%) with SBM vs EP. The addition of L to the supplements improved N digestibility by 6% in trial one (64.5 vs 60.6%) and 13% in trial two (62.9 vs 55.7%). No interactions between protein source and L were measured in either trial. Dry matter digestibility was not changed by protein source or L in either trial. Rumen propionate was increased and acetate to propionate ratio decreased when L was fed. Plasma urea N was lower over a 24 h sampling period when lambs were fed EP supplements compared with SBM supplements (11.07 vs 16.44 mg/100 ml); however, L did not appear to consistently alter the values. When steers were supplemented with the same protein sources during a 105-d winter pasture trial daily gains were not affected (P greater than .10) by either protein source or L (.429, .495, .476 and .514 kg/d for SBM, SBM+L, EP and EP+L, respectively) although numerically there did not appear to be main effect improvements due to EP and L.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of alfalfa maturity on energy utilization by cattle and nutrient digestibility by cattle and sheep.

Two comparative slaughter experiments conducted with growing beef steers (300 kg to 480 kg BW) fed alfalfa cubes demonstrated that animal performance diminished as alfalfa matured. In each trial, ADG (empty BW basis) was 10 to 20% greater from pre-bloom than from early-bloom alfalfa. Net energy for maintenance (Mcal/kg) followed a pattern similar to that of ADG, but NEg (Mcal/kg) did not decrease (P greater than .05) as alfalfa maturity increased. Digestion trials with steers and wethers clearly indicated significant reductions in apparent digestibilities of DM, energy, and cell wall fractions as alfalfa matured. Steers fed at 110% of maintenance in digestion Trails 1, 2, and 3 consistently digested cubed alfalfa to a greater extent than wethers fed the same alfalfa ground and pelleted. Digestion coefficients (percentages) for ADF, cellulose, NDF, and crude fiber were 5 to 14% greater for steers fed cubes than for wethers fed pellets. Regression equations calculated from results of three digestion trials indicate that digestible DM % and DE (Mcal/kg) could be predicted from ADF %, but they were 4 to 5% lower for wethers fed pelleted alfalfa than for steers fed cubes.