Effects of chemical additives on the fermentation quality and N distribution of alfalfa silage in south of China

In order to better utilize the last cut alfalfa harvested before killing frost in a high moisture environment, the effects of chemical additives on the quality of alfalfa silage were studied in south of China. The alfalfa was freshly harvested at branching stage, and wilted by dry matter content of about 300 g/kg (fresh matter basis). Silage was prepared by using a small‐scale silage fermentation system, where sucrose, potassium citrate, sodium carbonate, formic acid, acetic acid and propionic acid were used as silage additives, and no additives served as control. These silos were stored at ambient temperature (5‐20°C), and the silage qualities were analyzed after 120 days of fermentation. All additive treatments affected the chemical composition and N distribution, increased the water‐soluble content and crude protein contents, decreased non‐protein nitrogen (NPN) content, and enhanced the in vitro ruminal dry matter digestibility (except for sodium carbonate). Silages treated with organic acids were preserved with significantly (P < 0.05) lower pH value, ethanol content and NPN content compared with control. When the fermentation quality, chemical composition and N distribution were considered, the treatment with sucrose or organic acids resulted in high quality of alfalfa silage ensiled before killing frost, with formic acid having the best effect.     

Composition of formaldehyde- and formic acid-treated alfalfa and orchardgrass silages harvested at two maturities and their effects on intake and growth by Holstein heifers.

Alfalfa and orchardgrass herbages were each harvested at two maturities (May 22 to 25 vs June 5 to 7) in primary growth and directly ensiled with 5 kg of a mixture of 30% formic acid and 25% formaldehyde per metric ton of fresh herbage in upright conventional silos. Alfalfa silage contained less NDF (71%) and more N (150%) and hot-water-insoluble N (117%) than orchardgrass silage did. Major differences between silages were that orchardgrass contained 20.4 percentage units more NDF and 1.10 percentage units less N than alfalfa. The NDF increased 104% and total N decreased to 86% with advancing maturity. Twenty-eight yearling Holstein heifers (223 kg BW) were given ad libitum access to the four silages with trace mineral salt, and growth rate was measured in a 119-d period. Daily DE intake was 297 kcal/kg.75 BW for heifers fed alfalfa silage compared with 202 kcal/kg.75 BW for heifers fed orchardgrass silage. Daily gain was 992 g for heifers fed alfalfa compared with 661 g for heifers fed orchardgrass. Gross efficiency, or gain per unit of DE, was similar for heifers fed orchardgrass and alfalfa. Rate of gain was primarily a function of ad libitum intake of DE. Heifers fed alfalfa had greater plasma essential amino acid concentrations (122%) than those fed orchardgrass did. Late alfalfa produced greater ADG than orchardgrass harvested 2 wk earlier.     

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.     

Intake, digestibility, and composition of orchardgrass and alfalfa silages treated with cellulase, inoculant, and formic acid fed to lambs

The objectives of this study were to determine the effect of a cellulase (from Trichoderma longibrachiatum) alone or combined with a bacterial inoculant (Lactobacillus plantarum and Pediococcus cerevisiae) or formic acid on composition, intake, and digestibility of orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.) silages. Orchardgrass and alfalfa were harvested at the early heading stage and at the early bloom stage of maturity and wilted to approximately 22 and 32% DM, respectively. Forages were then ensiled in 100-L sealed barrels for at least 60 d before they were fed to lambs. Silage treated with cellulase had lower (P < .001) pH and lower (P < .001) acetic acid and NH3 N concentrations than untreated silage of both plant species and a higher (P = .004) lactic acid concentration than the control treatment of alfalfa silage. Fermentation characteristics of cellulase-treated silages, especially of alfalfa, were further enhanced by use of inoculant. Formic acid addition increased (P < .001), reducing sugar concentration of cellulase-treated orchardgrass and alfalfa silage by 90 and 154%, respectively, and decreased (P < .001) NH3 N concentration of cellulase-treated alfalfa silage by 19%. Averaged across plant species, cellulase, combined with inoculant or formic acid, resulted in 8 and 13% greater (P = .03) DMI, respectively, than the control silage. Extensive enzymatic cell-wall degradation during ensiling decreased (P = .003) NDF intake of cellulase-treated orchardgrass silage by 25% and decreased (P = .001) cellulose intake by 23%, when averaged across plant species. Addition of formic acid increased (P = .003) NDF intake of cellulase-treated orchardgrass silage by 19%. Averaged across species, cellulase application decreased (P < .05) silage NDF digestibility by 18%. Greater sugar and lower acetic acid, NH3 N, and NDF concentrations resulted in greater DMI of cellulase-treated silage than of control silage, when cellulase was combined with formic acid or inoculant.     

Utilization of energy and nitrogen by yearling Holstein cattle fed direct-cut alfalfa or orchardgrass ensiled with formic acid plus formaldehyde.

First-growth orchardgrass and alfalfa were harvested at two stages of maturity, treated with formic acid plus formaldehyde, and ensiled as direct-cut silage during 1978 and 1979. The 1978 silages were fed to eight yearling Holstein heifers (average BW 273 kg), and the 1979 silages were fed to eight yearling Holstein steers (average BW 264 kg) in replicated 4 x 4 Latin square experiments to measure total energy and N balance using the Beltsville open-circuit respiration calorimeters. Silage was offered daily at 70 g of DM/kg.75 BW, a rate that was essentially ad libitum for late-maturity orchardgrass, but restricted for the other three silages within each experiment. Cattle fed alfalfa used ME for growth with greater efficiency (55%) than did cattle fed orchardgrass (40%). Cattle fed orchardgrass achieved the same tissue N retention at a lower total N intake than did cattle fed alfalfa. Differences in tissue N retention were accounted for by differences in N intake insoluble in autoclaved ruminal fluid, but soluble in acid detergent, a fraction termed available N. At equal intake of ME and available N, cattle fed alfalfa gained more tissue energy than those fed orchardgrass and gained tissue protein similarly to cattle fed orchardgrass. Fractions composing digestible OM were different between forage types but similar within forage type between maturities at harvest. More efficient use of ME for growth by animals fed alfalfa compared with orchardgrass may be related to differences in digestible OM composition, load of digestive tract content, and composition of absorbed nutrients.     

不同添加剂对陇东紫花苜蓿青贮品质的影响

生物添加剂在促进牧草青贮发酵过程中有益菌和酶的活性、提高消化率和改善发酵品质等方面发挥着重要作用。本研究以初花期刈割的第1茬陇东紫花苜蓿(Medicago sativa)为原料,分析不同添加剂(甲酸、蔗糖、EM菌液和纤维素酶)对青贮发酵品质的影响。结果表明,4种添加剂处理组苜蓿青贮饲料感官评定得分均高于无添加剂对照组,pH、乙酸和氨态氮(NH₃-N)/总氮(TN)含量均显著(P<0.05)低于对照组,乳酸含量均显著(P<0.05)高于对照组,且未检测到丁酸和丙酸。4种添加剂处理组的粗蛋白质含量均显著(P<0.05)高于对照组,酸性洗涤纤维含量均显著(P<0.05)低于对照组。蔗糖组、EM菌液组和纤维素酶组的中性洗涤纤维含量均显著(P<0.05)低于甲酸组和对照组。粗灰分含量各组间无显著差异(P>0.05)。4种添加剂处理组的有氧稳定性均显著(P<0.05)高于对照组。上述结果说明,4种添加剂都可以提高陇东紫花苜蓿青贮的发酵品质、营养价值,延长有氧稳定性。但以纤维素酶组pH、乙酸和NH₃-N/TN含量最低,乳酸含量最高,青贮发酵品质最佳,建议在生产实践中大量推广应用。     

The effects of temperature on the silage microbiology and aerobic stability of corn and vetch-grain silages

Abstract

The purpose of the current work was to extend the study of the effect of temperature on silage microbiology, with or without formic acid, and on the aerobic stability of corn and vetch-grain silages.

The silage samples were ensiled in 1.0-l anaerobic jars, with and without formic acid, at room (20°C) or elevated temperatures (30–37°C). After 45 days of ensiling, the silages were subjected to an aerobic stability test at room (20°C) and elevated (30–37°C) temperatures. The most intensive deterioration occurred at 30–37°C. Samples incubated at 30–37°C had the highest yeast and mould count, most prolific CO₂ production.

The finding of the current study suggests that formic acid may decrease mould growth in silage samples. Unfortunately, formic acid does not reduce aerobic deterioration rate of silages. Applying a 5 g/kg formic acid on corn and vetch-grain silages was not very effective at high temperatures.     

Voluntary intake, growth rate, and tissue retention by Holstein steers fed formaldehyde- and formic acid-treated alfalfa and orchardgrass silages.

Alfalfa and orchardgrass herbages of similar digestibility were harvested at early and late maturity from primary growth and conserved as direct-cut silage using formic acid and formaldehyde simultaneously. Major compositional differences between the silages were lower NDF (principally hemicellulose) and a greater N content in alfalfa than in orchardgrass. An initial group of eight steers was slaughtered with a mean BW of 222 kg, and each of the four silages was fed to comparable groups of eight Holstein steers. Ad libitum DMI per unit of metabolic BW for alfalfa silages was 128% of that for orchardgrass silages. The ADG of steers fed alfalfa silages was 132% of that of steers fed orchardgrass silages. Despite greater ad libitum intake, total gut fill, as a percentage of BW, on alfalfa silages was 77% of that on orchardgrass silages. Daily empty BW gain of steers fed alfalfa silages was 158% of that of steers fed orchardgrass silages. Daily energy retention of steers fed alfalfa silages was 180% of that of steers fed orchardgrass silages. Steers fed alfalfa silages retained 140% more protein than steers fed orchardgrass silages did, but steers fed alfalfa silages retained only 71% as much protein energy relative to their total energy retention compared with steers fed orchardgrass silages. Differences in composition of daily energy retained were almost totally a result of differences in the total daily energy retention. Late alfalfa silage produced a greater daily gain than orchardgrass silage cut 2 wk earlier because greater intake compensated for lower digestibility.     

不同添加剂和原料含水量对紫花苜蓿青贮品质的互作效应

本试验探讨添加剂和水分对苜蓿(Medicago sativa L.)青贮品质的影响,苜蓿经晾晒其原料含水量分别达到51.29%,58.9%和70%后,分别添加植物乳杆菌、干酪乳杆菌、蔗糖、纤维素酶、绍曼乳酸菌、亚芯乳酸菌及复合添加剂并制作青贮饲料,在室温条件下袋贮30天后开启,分析其青贮品质。研究结果表明:添加剂和晾晒处理均可以有效提高苜蓿青贮的发酵品质(P0.05)。当青贮原料含水量为51.29%时,植物乳杆菌+纤维素酶混合处理的改善效果最好;当青贮原料含水量为58.9%时,纤维素酶处理组和植物乳杆菌+蔗糖混合处理组效果最好;当青贮样品含水量在70%时,蔗糖处理组和植物乳杆菌+蔗糖处理组效果最佳。原料含水量越低,其青贮效果越好。     

Effects of inoculants and environmental temperature on fermentation quality and bacterial diversity of alfalfa silage

To investigate the effects of inoculants and environmental temperature on fermentation quality and bacterial diversity of alfalfa silage, first‐cut alfalfa was ensiled with or without two screened lactic acid bacteria (LAB) strains, Lactobacillus plantarum, LP, and Lactobacillus casei, LC. Each treatment was divided into three parts and stored at 20°C, 30°C, 40°C, respectively. After 60 days ensiling, fermentation characteristics were measured and bacterial diversity was investigated by 16S ribosomal RNA gene sequencing using Illumina MiSeq platform. LP and LC decreased pH, coliform bacteria counts and increased lactic acid content at 20°C, and the two strains decreased pH, ammonia‐N concentration, coliform bacteria counts at 30°C. When the environmental temperature was 40°C, silage treated with LC showed lower LAB and coliform bacteria counts and higher lactic acid content than the untreated and LP treated silages. Butyric acid mainly appeared in silages stored at 40°C. The relative abundance of Lactobacillus in alfalfa silages stored at 20°C and 30°C was highest and increased after LP and LC were added. Garciella was another dominant genus in silages stored at 40°C. In conclusion, LP and LC improved fermentation quality of alfalfa silage by increasing Lactobacillus proportions at 20°C and 30°C; ensiling alfalfa at 40°C was difficult because of Garciella.     

Fermentation quality and chemical composition of shrub silage treated with lactic acid bacteria inoculants and cellulase additives

Effects of lactic acid bacteria (LAB) inoculants and cellulase additives on fermentation quality and chemical compositions of shrub silages were studied by using a small‐scale fermentation system. Two LAB inoculants of Qingbao (Lactobacillus plantarum, Pediococcus acidilacticii, Lactobacillus casei and Clostridium phage) and Caihe (Lactobacillus plantarum, Lactobacillus brevis and Pediococcus acidilactici) and a commercial cellulase made from Trichoderma reesei were used as additives for intermediate pea‐shrub, rush bushclover, arborescent ceratoides and shrubby silage preparation. The crude protein, neutral detergent fiber and water‐soluble carbohydrate contents of the four shrub materials were 10.1–14.2, 62.6–67.2 and 1.9–3.5% on a dry matter basis, respectively. All shrub silages had pH 3.40–4.43, ammonia‐N 0.1–0.2% g/kg and lactic acid 1.3–2.9% on a fresh matter basis. The silage quality of LAB‐inoculated silages did not have a greater effect than control silages, except shrubby silage preparation. Silages treated with the cellulase, the pH of rush bushclover and shrubby sweetvetch silage were significantly (P < 0.05) lower and the lactic acid content were significantly (P < 0.05) higher than the control silages. The results confirmed that shrub contained a relatively high content of crude protein; its silages can be preserved in good quality, and they are new potential resources for livestock feed.     

添加剂对苜蓿草渣青贮饲料品质的影响

为了研究不同添加剂对苜蓿草渣青贮饲料品质的影响,分别设置对照组、蔗糖(2%、3%、3.5%)、玉米粉(5%、7.5%、10%)、甲酸(0.2%、0.3%、0.4%)、乳酸菌(2.5g/t)、乳酸菌+蔗糖(2.5 g/t+2%、2.5 g/t+3%、2.5g/t+3.5%)、乳酸菌+玉米粉(2.5 g/t+5%、2.5 g/t+7.5%、2.5 g/t+10%)17个处理组,调制草渣青贮饲料。结果表明:草渣直接青贮饲料发酵品质较差;蔗糖、玉米粉和甲酸可以改善青贮饲料的发酵品质;单独添加乳酸菌不能提高青贮饲料品质;乳酸菌分别与蔗糖和玉米粉混合使用,与二者单独添加相比较,其青贮饲料的发酵品质和营养成分同样也未得到改善。     

添加剂和混合比例对裸燕麦和紫花苜蓿混贮品质的影响

探讨添加剂和不同混合比例对裸燕麦和紫花苜蓿混贮饲料品质的影响,为开展牧草混播及调制高质量的混合青贮饲料提供参考。以裸燕麦和紫花苜蓿为原料,按质量比1∶1、2∶1和1∶2进行混合青贮,并分别加入0.4% 甲酸(formic acid,FA)或2%蔗糖(sucrose,S),青贮60 d后测定混合青贮饲料的发酵品质和营养物质含量。结果显示,裸燕麦与苜蓿混合比例为2∶1时青贮饲料的感官评价上均优于其余2种混合比例,添加0.4%甲酸或者2%蔗糖,感官评定为优并显著高于对照组(P<0.05)。混合青贮饲料的发酵品质随裸燕麦比例增加而不同程度提高。其中,pH值随裸燕麦比例增加而逐渐降低;在裸燕麦与苜蓿混合比例在2∶1时,添加2%蔗糖组乳酸(lactic acid,LA)含量显著高于对照及0.4%甲酸处理组(P<0.05),且与另外2种混合比例的处理组相比差异均显著(P<0.05);此混合比例下添加0.4%甲酸处理组pH值和氨态氮/总氮(AN/TN)较低,乙酸(acetic acid,AA)和总挥发性脂肪酸(total VFA,TVFAs)含量最低,乳酸含量及乳酸/乙酸(LA/AA)较高,丙酸(propionic acid,PA)和丁酸(butyrate acid,BA)含量极低未检出,V-Score评分最高,总体发酵品质最佳。随苜蓿比例增加,混贮饲料CP含量提高,纤维组分(NDF、ADF和HC)含量降低,青贮饲料养分更加均衡,但添加剂对青贮饲料营养成分影响不大。裸燕麦与紫花苜蓿混合青贮可形成养分互补,提高营养价值;加入适量甲酸或蔗糖有助于抑制不良发酵,提高发酵品质。     

添加剂对紫花苜蓿青贮饲料发酵品质的影响

为提高紫花苜蓿青贮饲料的发酵品质,抑制不饱和脂肪酸的损失,以无添加剂为对照,研究了添加剂：苯甲酸钠、酪蛋白酸钠、十六烷酸、糖蜜和丙酸,对紫花苜蓿青贮饲料发酵品质和脂肪酸的影响。青贮65 d后开窖,检测发酵品质指标和各种脂肪酸的含量。结果表明：对照组的pH低于4.50,乳酸含量达到54.25 g·kg^-1 DM,丁酸含量低于5.00 g·kg^-1 DM,弗氏评分为64.33,具有良好的发酵品质。与青贮前相比,青贮后苜蓿青贮饲料中的亚油酸（C18：2n6）和亚麻酸（C18：3n3）的含量显著增加（P<0.05）。青贮后,与对照组相比,十六烷酸和酪蛋白酸钠添加组分别不显著（P>0.05）和显著地（P<0.05）降低了乳酸含量;酪蛋白酸钠添加组增加了丁酸含量（P<0.05）;二者的弗氏评分低于50.00,降低了发酵品质。与此相反,苯甲酸钠、丙酸和糖蜜添加组不同程度地增加了乳酸含量,降低了pH,减少了氨态氮和酸性洗涤纤维的含量,弗氏评分分别为70.33、74.33和67.67,进一步提高了青贮发酵品质。与对照相比,苯甲酸钠和丙酸添加组不同程度地增加了C18：2n6或C18：3n3的含量,而糖蜜添加组降低了C18：2n6和C18：3n3的含量（P<0.05）。综上所述,丙酸和苯甲酸钠适宜于作为青贮添加剂生产优质紫花苜蓿青贮饲料。     

Effect of inoculants on whole-crop barley silage fermentation and dry matter disappearance in situ

Whole-crop barley harvested at the mid-dough stage was ensiled in 3-L laboratory silos either directly (at 30.7% DM) or after wilting (37.8% DM), and with or without application of Inoculant A, B, or D. Each inoculant contained multiple strains of Lactobacillus plantarum and Enterococcus faecium. Two silos per treatment were opened on d 1, 3, 7, 15, and 47 for silage analysis. Wilted silages had higher (P < 0.05) pH than unwilted silages, and Inoculant B (unwilted crop) and Inoculants A, B, and D (wilted crop) decreased (P < 0.05) silage pH compared to the controls. Reducing sugars concentration was 36% lower (P < 0.05), on average, in the wilted than in the unwilted silages. Silages prepared with Inoculants B or D had lower (P < 0.05) concentrations of reducing sugars than the control. Wilting of the barley crop further increased the difference between inoculated and control silages (wilting x inoculation P < 0.05). Neither wilting nor silage inoculants affected concentrations of nonprotein N, ammonia N, or free amino acid N in silage. Wilting did not affect the concentration of lactic acid bacteria (LAB) in the silages. Across DM levels, inoculant-treated silages had larger (P < 0.01) populations of LAB than did the uninoculated controls (7.1 x 10(9) vs 2.3 x 10(9) cfu/g silage DM). Wilting resulted in lesser (P < 0.05) silage lactic acid concentration than the directly ensiled crop. At both DM levels, lactic acid concentration was higher (P < 0.001) in inoculated silages than in controls. The in situ soluble and potentially degradable fractions of silage DM were not affected by wilting or inoculant treatment. The rate of degradation of the potentially degradable silage DM was 35% lower (P < 0.05) in wilted than in unwilted silage. As a result, the calculated effective degradability of silage DM was lower (P < 0.001) in wilted than in unwilted silage. Inoculants did not influence the rate of degradation or effective degradability of silage DM in the rumen. Whole-crop barley ensiled at approximately 30% DM (without wilting) contained higher concentrations of soluble sugars and lactic acid and had higher ruminal degradability of DM than wilted silage (38% DM). Although inoculants did not improve DM degradability of barley silage, lower terminal pH and increased concentrations of lactic acid may improve aerobic stability upon feed-out.     

Effect of ensiling and silage additives on fatty acid composition of ryegrass and corn experimental silages

Two experiments were conducted using laboratory mini-silos to study the effect of ensiling and silage additives on fatty acid (FA) composition, including minor or unusual FA, of ryegrass and corn silages. Ryegrass was ensiled for 12 wk with no additives, with the addition of a bacterial inoculant or formic acid. Corn was ensiled for 9 wk without additives, with the addition of a bacterial inoculant or calcium formate. Ensiling affected both total FA content and FA composition of ryegrass silages. Total FA concentration increased (P < 0.001) during ryegrass ensiling. The proportions (g/100 g of total FA) of the major unsaturated FA, 18:3n-3 and 18:2n-6, were not affected (P > 0.05) by ensiling. However, their concentration (mg/g of DM) in silages was greater (P=0.017 and P=0.001, respectively) than in fresh ryegrass. Two 18:2 FA (trans-11,cis-15 and cis-9,cis-15) that were not originally present in the fresh ryegrass were detected in silages. Silage additives affected the FA composition of ryegrass silages, mostly by increasing the proportions of SFA, but not on total FA concentration. Ensiling did not affect (P=0.83) total FA content of corn silages; however, FA composition was affected, mostly by decreasing the proportions of 18:2n-6 and 18:3n-3. Silage additives had no effect on corn silage FA composition. Exposing corn silages to air resulted in no oxidation of FA or reduction in total FA content or composition.     

Effect of a preparation containing lactic fermentation bacteria on the hygienic status and aerobic stability of silages

The objective of this study was to determine the influence of biological silage additive (Bonsilage) on the hygiene quality and nutritive value of maize and grass-legume silages. The experiments were conducted on FAO 240 maize (Zea mays L.) and a mixture of italian ryegrass (Lolium multiflorum L.), 50% with alfalfa (Medicago media Pers.), 50%. Group 1 was a control and comprised silage without any additives, group 2 was ensiled with the addition of 4 cm3 kg(-1) biological silage additive. After 60 days of silage process individual silages were subjected to microbiological composition, and chemical analyses of silages were also determined. Similar analyses were repeated at day 7 following exposure to oxygen. The applied biological silage additive was found to reduce (P<0.05) numbers of Clostridium, Enterobacteriaceae, yeasts and mold fungi cells, and increase (P<0.05) the number of LAB (lactic acid bacteria) in comparison with the control in both silages. Chemical analysis of the maize silage showed that the biological additive caused an increase (P<0.05) in DM (dry matter), CP (crude protein), WSC (water soluble carbohydrates), LA (lactic acid), AA (acetic acid), ethanol, and a decrease (P<0.05) in the concentration of BA (butyric acid), N-NH3 and pH value in comparison with the control. Chemical analysis of silage samples from the grass-legume mixture showed that the additive caused an increase (P<0.05) in the content of DM, CP, WSC, LA and AA in comparison with the control. Samples of silage with the addition of an inoculant were characterized by a lower (P<0.05) content of BA, N-NH3, ethanol and pH value. The biological additive impoved the aerobic stability of silages in the aerobic phase.     

不同添加剂对拉伸膜裹包苜蓿青贮饲料体外消化率的影响

为评价不同添加剂对拉伸膜裹包苜蓿青贮饲料养分体外消化率的影响,采用两步法测定体外干物质消化率（IVDMD）和体外粗蛋白消化率（IVCPD）,采用一步法测定体外中性洗涤纤维消化率（IVNDFD）和体外酸性洗涤纤维消化率（IVADFD）。结果表明,苜蓿青贮后的养分消化率低于原料;绿汁发酵液处理组拉伸膜裹包苜蓿青贮的IVDMD显著高于甲酸处理组（P〈0.05）;不同添加剂处理拉伸膜裹包苜蓿青贮饲料的IVCPD没有显著差异;甲酸处理组和绿汁发酵液处理组拉伸膜裹包苜蓿青贮饲料的IVNDFD和IVADFD显著低于对照处理组（P〈0.05）。结论表明,苜蓿青贮后,养分的消化率下降,不同添加剂对苜蓿纤维的消化率有影响。     

生物添加剂和含水率对紫花苜蓿和猫尾草青贮发酵品质的影响

试验旨在研究紫花苜蓿绿汁发酵液（AFGJ）、猫尾草绿汁发酵液（TFGJ）、乳酸菌制剂（LAB）、纤维素酶（CEL）及LAB＋CEL（MIX）对紫花苜蓿和猫尾草青贮发酵品质的影响。用紫花苜蓿和猫尾草各2种含水率（高、低）的原料制作了青贮。每个处理设2次重复，常温下贮存50d，开封后测定青贮的发酵品质。研究结果表明，添加剂对紫花苜蓿和猫尾草青贮的发酵品质有显著影响（P〈0．05），除AFGJ和TFGJ高含水率紫花苜蓿青贮外，各种添加剂均不同程度地改善了高、低含水率紫花苜蓿和猫尾草青贮的发酵品质；含水率对紫花苜蓿和猫尾草青贮的发酵品质有显著影响（P〈0．05），2种牧草均是低含水率优于高含水率青贮的发酵品质；添加剂和含水率对青贮的发酵品质有显著的交互作用（P〈0．05）。综合各项指标，在高、低含水率紫花苜蓿青贮中均以添加MIX效果最好；在高含水率猫尾草青贮中，添加TFGJ和AFGJ效果相近且优于其他添加剂；在低含水率猫尾草青贮中添加AFGJ、TFGJ、LAB和MIX效果相近，且优于添加CEL。结果表明，适当降低原料含水率并选择适宜的添加剂可调制优质青贮。     

Inhibition of proteolysis at harvest using heat in alfalfa silages: effects on silage composition and digestion by sheep

Heat treatment at harvest was used to investigate the effects of proteolysis on silage composition and digestion by sheep. Four alfalfa (Medicago sativa) silages were prepared, two from mid-bloom and two from pre-bloom crops from the same field. Mid-bloom alfalfa was conserved with formic acid as two unwilted silages, either without (unwilted control; UWC) or after heat treatment (unwilted heated; UWH) applied as steam for 1 min. Pre-bloom alfalfa was ensiled either after 24 h wilting (wilted control; WC) or after heating in a crop dehydrator for 2 min (wilted control; WH). Heated treatments were inoculated with Lactobacillus plantarum. Eight wethers, cannulated in the rumen and duodenum, were given the silages to determine the effects of heat treatment on digestion. Heat treatment inhibited protease activity and reduced protein catabolism in the silo. In unwilted silages, heat treatment had no effects (P greater than .05) on OM or N digestion, but it reduced (P less than .05) CP degradability in the rumen. In wilted silages, heat treatment reduced (P less than .05) apparent OM digestion in the rumen and increased (P less than .05) the proportion of N intake flowing to the intestines as non-ammonia N (NAN). Efficiency of microbial protein synthesis also was increased (P less than .01). Absorption of N posterior to the duodenum was increased (P less than .05) in WH compared to WC, but there was no effect (P greater than .05) of heat treatment on apparent total tract N digestibility.(ABSTRACT TRUNCATED AT 250 WORDS)