Effects of high-sugar ryegrass silage and mixtures with red clover silage on ruminant digestion. 2. Lipids

The experiment investigated the digestion of lipids from different forage silages in beef steers. Six Hereford x Friesian steers prepared with rumen and duodenal cannulas were given ad libitum access to a high-sugar grass silage, control grass silage, red clover silage, or mixtures of the red clover and each of the grass silages (50:50, DM basis). The experiment was conducted as an incomplete 5 x 5 Latin square, with an additional randomly repeated sequence. Total fatty acid and C18:3n-3 concentrations were greater (P < 0.05) for the high-sugar grass silage than the control grass silage or the red clover silage. Dry matter and total fatty acid intake were less (P < 0.05) for steers fed the control grass silage than for steers fed the other diets. Duodenal flow of C18:3n-3 was greater (P < 0.05), and flows of C18:0 and total C18:1 trans were less (P < 0.05), for the red clover silage compared with the 2 grass silage diets, with the mixtures intermediate. These results were supported by a reduction (P < 0.05) in biohydrogenation of C18:3n-3 for the red clover silage, with the mixtures again being intermediate. Flows of total branched- and odd-chain fatty acids were greater (P < 0.05) for the high-sugar grass silage diet, possibly as a result of greater microbial flow, because these fatty acids are associated with bacterial lipid. Duodenal flows of the chlorophyll metabolite, phytanic acid, were greater (P < 0.05) for animals fed the high-sugar grass silage treatments compared with the other treatments. These results confirm the potential for modifying the fatty acid composition of ruminant products by feeding red clover silage.     

Apparent ruminal degradation and rumen escape of soluble nitrogen fractions in grass and grass silage administered intraruminally to lactating dairy cows

The main objective of this study was to investigate in vivo ruminal degradation and rumen escape of soluble N fractions in grass and grass silage. Soluble protein and long-chain peptides (PLP), small peptides (SP) and free AA (FAA) were obtained from fresh grass and grass silages fertilized with different levels of N. Soluble extracts from the forages were pulse dosed into the rumen of three cannulated lactating dairy cows, and a simple or complex model was used to examine the kinetics of the soluble N fractions in the rumen. When soluble extracts from silage were investigated, pulse dosages of total nonammonia N (NAN) were 21, 27, and 32 g, while for fresh grass only dosages of 20 g were ruminally administered. In the silage extracts, mean proportions of PLP-N, SP-N, and FAA-N in the NAN were 30, 52, and 18%, respectively, whereas in the fresh grass the corresponding values were 67, 20, and 13%. From silage extracts, all three soluble N fractions showed a linear decrease (P < 0.05) in degradation rate and an increase (P < 0.05) in ruminal escape with increasing dosage. In silage, mean degradation rates, parameterized from the complex model, were 230, 214, and 334%/h for PLP-N, SP-N, and FAA-N, respectively, and the ruminal escape was highest (P < 0.05) for SP-N (11.2% of dose) and lowest (P < 0.05) for FAA-N (5.0% of dose). No differences in degradation rate and ruminal escape between fresh grass and silage were observed. However, the proportion of N dose converted to ammonia was only 24% in the fresh grass, whereas for the silages a mean value of 76% was found. From this study, it is concluded that a significant amount of dietary soluble N escapes ruminal degradation, and thus contributes to the intestinal AA supply. Moreover, if the main aim is to study degradation kinetics of individual N fractions, a complex model should be used in the evaluation. This model can also be used to study ruminal synchronization of N and energy for microbial growth.     

Inhibition of proteolysis in alfalfa silages using heat at harvest: effects on digestion in the rumen, voluntary intake and animal performance

The effects of proteolysis on digestion and animal performance were studied using heat to inhibit proteolysis at ensiling. Alfalfa (Medicago sativa) was ensiled either after wilting for 24 h (control; C) or after heating (100 degrees C) in a crop dehydrator for 2 min (heated; H). In Exp. 1, eight wethers, cannulated in the rumen and duodenum, were given the silages to determine the effects of heat treatment of alfalfa on the digestion of silage. In Exp. 2, growing lambs had ad libitum access to the silages to determine the effects of heat treatment on intake, animal performance and body composition. Heat treatment inhibited protease activity; protein N accounted for 33.5 and 61.3% and ammonia N 15.5 and 5.1% of total N in C and H silages, respectively. Heat treatment reduced mean post-feeding ruminal ammonia N concentration (P less than .05), ruminal pH (P less than .05) and the acetate: propionate ratio (P less than .001) in ruminal fluid. Heat treatment increased duodenal flow of non-ammonia N (P less than .05) and amino acids (P less than .05), the amount of N absorbed (P less than .05) in the small plus large intestine and also increased the efficiency of microbial protein synthesis (P less than .05). In Exp. 2, although intake and gain were higher (P less than .001) for H-fed than for C-fed lambs, there were no differences (P greater than .05) in empty body composition. The results indicated that inhibition of proteolysis by heat treatment at ensiling can increase utilization of silage N within the rumen, increase voluntary intake and result in a higher rate of gain by lambs fed alfalfa silage.     

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)     

Effect of whole-crop pea (Pisum sativum L.) silages differing in condensed tannin content as a substitute for grass silage and soybean meal on the performance, metabolism, and carcass characteristics of lambs

Two experiments were conducted to investigate the effect of inclusion of whole-crop pea (WCP) silages, differing in condensed tannin content, as a substitute for grass silage (GS) and soybean meal on lamb metabolism, performance, plasma metabolites, digestibility, and carcass characteristics. In both experiments lambs were offered either solely GS or a 50:50 mix on a DM basis of GS with either low-tannin (LTPS) or high-tannin (HTPS) pea silage ad libitum. Each forage mix was fed with either 400 g/d of low-protein (LP) concentrate or 400 g/d of LP with an additional 200 g/d of pelletized soybean meal (HP), resulting in 6 dietary treatments. Experiment 1 examined the effects of the diets on metabolism, digestibility, and N balance using 6 lambs in 4 periods of 21 d in an incomplete crossover design. Experiment 2 used 48 lambs and examined the effects of the diets on ADG, plasma metabolites, and carcass characteristics over 56 d. Both experiments were analyzed using a 3 × 2 factorial arrangement of treatments. In Exp. 1, lambs offered the LTPS diets had a greater (P < 0.05) digestibility of DM and OM than those offered the GS diets. Lambs offered the WCP silages had an increased (P < 0.05) N intake, N output, and digestibility of GE compared with those offered GS. Mean N digestibility was greatest (P < 0.05) in lambs offered LTPS. Lambs offered HP diets had increased (P < 0.001) digestibility of DM, OM, GE and N, and N- intake, output, retention, and digestibility compared with those offered the LP diets. In Exp. 2, there was no effect (P > 0.05) of forage type on intake, slaughter BW, or feed conversion efficiency (FCE). However, lambs offered the LTPS had a greater (P < 0.05) ADG than those offered the GS diets. Feeding diets containing HP increased (P < 0.001) total DMI, slaughter BW, ADG, and FCE. Lambs offered the WCP had a greater (P < 0.05) plasma β-hydroxybutyrate and urea concentration compared with those offered the GS diets. Feeding lambs HP diets increased (P < 0.05) plasma urea and total protein. Forage mix had no effect (P > 0.05) on carcass composition except for fat depth, which was greater (P < 0.05) in lambs offered WCP silage. Diets containing the HP increased (P < 0.05) carcass weight, hind leg circumference, chop dimensions, and kidney weight. It was concluded that lambs offered LTPS performed better than those offered GS and that LTPS has a concentrate sparing effect. Additionally, the increased tannin concentration in HTPS did not increase performance over lambs offered either GS or LTPS.     

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.     

Grass silage versus maize silage effects on retail packaged beef quality

The effects of three preslaughter diets on heifer beef quality were investigated. Heifers (n = 45) were divided into three groups and fed for ad libitum consumption either maize silage, grass silage, or a 50:50 mixture of maize silage and grass silage. Meat quality was determined by measuring color, lipid oxidation, alpha-tocopherol levels, and fatty acid composition. Beef from the maize silage group had poorest color stability (P < 0.05), whereas beef from the grass silage diet had best (P < 0.05) color stability. The visual panel least preferred the maize silage group after 2 or more days of display, and lipid oxidation was significantly (P < 0.001) higher in this group compared to the 50:50 maize:grass silage and grass silage groups. There was a significant (P < 0.001) difference in the alpha-tocopherol levels detected in the meat from the three dietary groups. Alpha-tocopherol levels increased in the order: maize silage < 50:50 maize:grass silage < grass silage, at levels of 2.08, 2.95, and 3.84 microg/g meat, respectively. Fatty acid analysis indicated 18:3 was significantly (P < 0.001) lower in the maize silage-fed group than in the maize:grass silage and grass silage groups. However, 18:3 was significantly (P < 0.001) higher in the grass silage group than in the other two groups. There were no significant differences in all other fatty acids among the three dietary groups. It was concluded that beef from grass silage-fed animals had better overall quality in terms of color, lipid oxidation, and alpha-tocopherol levels than beef from maize silage fed animals.     

Intake of direct cut or wilted grass silage as related to chewing behavior, ruminal characteristics and site and extent of digestion by heifers

Six nonpregnant Friesian heifers (516 kg avg BW) with ruminal and duodenal cannulas were used to examine intake of direct cut (DC) or wilted (W) grass silage in relation to chewing behavior, ruminal characteristics and site and extent of digestion. Dry matter content of the silages was 20.3% and 40.3%, and feed intake averaged 1.88% and 2.17% of BW (P less than .01), respectively. Mean ruminal osmolality was 291 mosm/liter for the DC and 318 mosm/liter for the W silage (P less than .05), with extreme values exceeding 350 mosm/liter for the W silage at 1 h to 2 h postfeeding. There was a shift from eating to ruminating on W silage associated with a longer duration of the average rumination bolus cycle (P less than .01). Duration of chewing time per kilogram of DM intake was 103.5 min and 91.7 min (P less than .05) for the DC and W silages, respectively. Fecal mean particle length was 2.2 times greater (P less than .01), accompanied by higher spread coefficients (P less than .001), for the W silage. No differences occurred between silages in ruminal digestibility of OM and NDF. In the total digestive tract, apparent digestibilities of OM and NDF were depressed after wilting grass prior to ensiling (P less than .01), but the proportion of digestible OM apparently digested in the rumen was .74 for both silages.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

瘤胃纤维素降解菌系对灭菌水稻秸秆结构性碳水化合物降解的影响

为了提高水稻秸秆的青贮发酵品质,本研究旨在从黑白花奶牛瘤胃中筛选出具有降解纤维素能力的兼性厌氧复合菌系,探讨其对水稻秸秆青贮过程中结构性碳水化合物降解及发酵品质的影响。试验采集了黑白花奶牛瘤胃内容物,经富集培养、刚果红染色初筛,耐酸诱导,滤纸降解复筛,酶活力测定,获得高效兼性厌氧纤维素降解复合菌系M6。试验设4个处理组：1）水稻秸秆直接自然青贮（CK）组;2）灭菌后水稻秸秆青贮（IRR）组;3）灭菌水稻秸秆接种复合乳酸菌（CLAB）青贮组;4）灭菌水稻秸秆接种复合菌系（M6）青贮组,分别于青贮3、6、15、45、60和90 d后开窖取样分析。结果表明,青贮3 d后,M6处理组pH始终低于其他各组,青贮第60天达到最低值（4.62）。青贮45 d后,M6处理组乳酸含量始终显著高于其他各组（P<0.05）,且在青贮90 d达到最高值（23.90 g·kg^-1 DM）。青贮15 d后,中性洗涤纤维、酸性洗涤纤维和纤维素含量在M6组均显著低于其他各组（P<0.05）,且在第90天达到最低值。青贮60 d后,IRR和M6组保持较高水平的水溶性碳水化合物含量,其次为CLAB组。综上所述,复合菌系M6在水稻秸秆青贮过程中具有降解粗纤维和促进乳酸发酵的作用,添加纤维素降解复合菌系可有效改善水稻秸秆青贮发酵品质,为青贮添加剂的研发与应用提供了理论依据。     

The effect of fermentation quality on the voluntary intake of grass silage by growing cattle fed silage as the sole feed

This study was designed to separate the effect of fermentation quality on voluntary intake of grass silage from other feed factors affecting intake. Variations in DMI were quantified, and the impact on intake was modeled. The relationships between individual silage components and intake were examined. A partially balanced changeover experiment with 30 Norwegian Red steers (137 +/- 16.4 kg of BW) was carried out to determine the intake of 24 silages and of hay harvested from the same parent crop within 60 h. Five forages were fed at a time in each of five 3-wk periods. Every 3-wk period was preceded by 2 wk of feeding a standard silage. Silage DMI ranged from 1.79 to 2.65, with a mean of 2.38 kg x 100 kg of BW(-1) x d(-1). Hay DMI averaged 2.43 kg x 100 kg of BW(-1) x d(-1). Ranges (mean) for the composition of silages were as follows: DM, 166 to 237 (213) g/kg; water-soluble carbohydrates, 16.3 to 70.9 (33.0) g/kg of DM; acetic acid, 11.5 to 64.7 (28.6) g/kg of DM; propionic acid, 0 to 5.2 (1.0) g/kg of DM; butyric acid, 0 to 25.1 (6.0) g/kg of DM; lactic acid, 2.2 to 102 (49.3) g/kg of DM; and NH3-N (not corrected for additive-derived N), 89.3 to 255 (153) g/kg of total N. Silage DMI was closely (P < 0.05) related to DM, ADL, VFA, lactic acid, total acids, the lactic acid:total acids ratio, ADIN, NH3-N (not corrected), histamine, tryptamine, cadaverine, and the total sum of amines (the explained variation in intake ranged from 14 to 53%). The 2 best models describing silage DMI included concentrations in the silage of propionic acid, butyric acid, and lactic acid, and these models explained 75 and 84% of the variation in DMI. The strong correlation (r = 0.84, P < 0.05) between total NH3-N and butyric acid concentrations in silages indicates that these variables described the same variation pattern. The inclusion of NH3-N in the equations describing the effect of fermentation quality on DMI of low-DM grass silage was less useful than that of butyric acid. This was due to the confounded relationship between the NH3-N concentration in silages and the use of ammonium-containing preservatives and to difficulties in correcting for the added ammonium.     

青贮添加剂对稻草青贮品质和有氧稳定性的影响

试验旨在探讨不同添加剂对青贮稻草品质和有氧稳定性的影响。稻草青贮时,分别添加乳酸菌(L)、乳酸菌+糖蜜(LM)、乳酸菌+纤维素酶(LC)和乳酸菌+糖蜜+纤维素酶(LMC),乳酸菌、纤维素酶和糖蜜剂量分别为5×10⁵ cfu/g、0.6 IU/g、20 mg/g,贮存90 d后开包检测。综合评定青贮稻草的青贮质量,测定常规营养成分,浸提液的pH值、氨态氮和有机酸的含量并测定稻草的有氧稳定性。试验结果:L组、LM组、LC组和LMC组的总综合评分显著高于对照组(P<0.05)。LC、LMC组的酸性洗涤纤维含量显著低于对照组(P<0.05),提高了剩余可溶性碳水化合物的含量。与对照组相比,各处理组均提高了乳酸的含量;LC和LMC组显著提高了乳酸的含量(P<0.05)。对照组的总有机酸含量显著低于LC和LMC组(P<0.05),但是和L、LM组差异不显著(P>0.05)。各组的有氧稳定性和有氧损失均无显著差异(P>0.05)。结果表明:添加乳酸菌,提高了乳酸的含量和综合评分;在乳酸菌的基础上,添加糖蜜或是与纤维素酶的组合,有利于提升发酵品质。     

Prediction of nutritive values in grass silages: II. Degradability of nitrogen and dry matter using digestibility, chemical composition, and fermentation data

One hundred thirty-six perennial rye-grass silages with wide variations in quality were evaluated for N and DM degradability in three beef steers offered grass silage of medium quality ad libitum. The silages were incubated in the rumen of each animal in triplicate for 0, 6, 12, 24, 48, and 72 h, respectively. The disappearance rates of N or DM were used to calculate the readily soluble fraction ("a" value), potentially degradable fraction ("b" value), and the fractional degradation rate of"b" ("c" value). The effective degradability (P) of N or DM was then estimated assuming a ruminal outflow rate of 0.02, 0.05, or 0.08/h (P0.02, P0.05, or P0.08). The objective was to use these data to develop prediction equations for N and DM degradability in grass silages. There were considerable variations in "a," "b," and "c" values and the P0.02, P0.05, or P0.08 of N and DM (e.g., the P0.02 of N ranged from 75.0 to 93.4% and the P0.02 of DM from 51.5 to 82.5%). The P0.02, P0.05, or P0.08 of N and DM were negatively related (P < 0.001) to ADF, NDF, and lignin concentrations but positively related (P < 0.001) to protein fractions (CP, soluble CP, and true protein concentrations) and digestibility of DM, OM, GE, CP, and NDF and digestible OM in the total DM (measured with sheep). The N and DM degradability data were also positively related to silage lactic acid concentration, but the relationships between DM degradability data and pH, ammonia N/total N, and VFA concentration in silages were negative (P < 0.05). Several sets of prediction equations (linear and multiple) were thus developed for N and DM degradability using CP or NDF concentration, "a" value or digestibility data as primary predictors, together with or without other nutrient concentration and silage fermentation variables. All these relationships were highly significant (P < 0.001), and each predictor had a significant effect on the relationship (P < 0.05). The R2 values in multiple regression for N and DM degradability were generally over 0.70 and higher than in linear regression equations. Four equations were also developed to convert N and DM degradability at a given ruminal outflow rate, predicted using the above-mentioned equations, to their counterparts at any ruminal outflow rate (0.02 to 0.10/h), respectively.     

青贮菌剂在苜蓿裹包青贮中的应用效果

在苜蓿裹包青贮中添加3种不同青贮菌剂JD6、MMD3、X3Q2,分析青贮苜蓿的营养品质,微生物数量以及瘤胃降解率的变化,以研究3种青贮菌剂在裹包青贮条件下对苜蓿青贮的影响。结果表明,青贮5个月后,添加青贮菌剂可以显著降低pH值(P<0.05)、NH3/TN值(P<0.05),减少丁酸含量(P<0.01),有利于保存青贮物的营养成分,提高青贮品质。添加青贮菌剂对青贮物的NDF、ADF含量没有影响,对青贮产物干物质和NDF的瘤胃降解率没有影响。添加青贮菌剂可以提高青贮产物中乙酸含量(P<0.05),减少酵母菌和霉菌数量(P<0.05)。3种青贮菌剂在苜蓿裹包青贮试验中,有利于抑制有害微生物,保存苜蓿营养成分,提高苜蓿青贮品质和有氧稳定性。     

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.     

Rumen fermentation, microbial protein synthesis, and nutrient flow to the omasum in cattle offered corn silage, grass silage, or whole-crop wheat

The objectives of this study were to determine the relative effect of feeding corn silage (CS), fermented whole-crop wheat (FWCW), and urea-treated processed whole-crop wheat (UPWCW) compared with grass silage (GS), each supplemented with concentrates, on forage intake, ruminal fermentation, microbial protein synthesis, some plasma metabolites, and ruminal and total tract digestibility in cattle. Four ruminally fistulated steers with a mean BW of 509 kg (SD 6.3) were used in a 4 x 4 Latin square-designed experiment with each period lasting 21 d. The omasal sampling technique in combination with a triple marker method was used to measure nutrient flows to the omasum with Co-EDTA, Yb acetate, and indigestible NDF as liquid, small particle, and large particle phase markers, respectively. Microbial N flow was assessed from purine base concentrations. Steers fed CS, FWCW, and UPWCW consumed 2.7, 2.4, and 2.6 kg/d more (P < 0.05) forage and total DMI, respectively, than those fed GS-based diets. Rumen pH (P = 0.07) and lactic acid (P = 0.11) concentration did not differ between the forages. Rumen concentration of NH(3)-N was greatest for UPWCW and least for CS (P < 0.001). Total VFA concentrations were greater (P < 0.05) for CS than GS and UPWCW, with FWCW being intermediate. Acetate-to-propionate ratio (P < 0.05) was greater (P < 0.05) for UPWCW than the other forages, which did not differ. Apparent ruminal digestion of OM (P < 0.05) was less for CS, FWCW, and UPWCW than GS. Ruminal NDF digestibility was greater (P < 0.01) for GS than the other forages, which did not differ (P > or = 0.06). Total tract NDF digestibility was less (P < 0.05) for UPWCW than the other forages, with GS being greatest and CS and FWCW being intermediate. Starch intake was less (P < 0.001) for GS than the other forages, but there was no effect of forage on omasal starch flow (P = 0.23) or ruminal digestibility (P = 0.88). Flow of non-NH(3)-N and microbial N was greater (P < 0.05) for CS, FWCW, and UPWCW than GS. Efficiency of microbial N synthesis was greater (P < 0.05) for FWCW than GS and CS, with UPWCW being intermediate. Plasma beta-hydroxybutyrate concentrations were greatest with CS and least for GS (P < 0.001), whereas concentrations of plasma urea were least for CS and greatest for UPWCW (P < 0.001). In conclusion, feeding alternative forages to GS can significantly increase feed DMI and alter rumen fermentation and site of nutrient digestion when offered to cattle supplemented with 3 kg of concentrate daily.     

Fermentation quality and nutritive value of a total mixed ration silage containing coffee grounds at ten or twenty percent of dry matter

Six wethers were used in a replicated 3 x 3 Latin square to study the fermentation quality and nutritive value of total mixed ration (TMR) silages that included wet coffee grounds (WCG). The TMR were prepared using a commercial compound feed, timothy hay, alfalfa hay, dried beet pulp, and a vitamin-mineral supplement in a ratio of 36.5:30:20:12:1.5, respectively, on a DM basis, with timothy hay and alfalfa hay being replaced by WCG at 0, 10, or 20%. All TMR silages, irrespective of WCG addition, were well preserved, with a low pH and ammonia-N content and a high lactic acid content. Intakes by wethers of TMR silages containing 0 and 10% WCG were 96.6 and 94.8 g/kg of BW(0.75), and did not differ (P > 0.05). Intake of TMR silage containing 20% WCG was 76.8 g/kg of BW(0.75), which was equal to 80% of that of the TMR silage with no WCG (quadratic: P < 0.01). Increasing concentrations of WCG in the rations decreased the digestibility of DM, CP, ADF, NDF, and energy, and increased that of ether extract (P < 0.05). The TDN and DE contents of the TMR silages with 0 and 10% WCG were similar, but the TMR silage with 20% WCG was lower (P < 0.05). With progressive increases in WCG concentrations, N intake did not differ, but fecal and urinary N increased linearly (P < 0.001), and retained N decreased linearly (P < 0.001). This study demonstrated that the proportion of WCG to be incorporated into TMR silages should not exceed 10% of the DM.     

The effect of storage on the estrogenic effect of red clover silage.

Pure red clover was selected for plant estrogen analyses from the fresh fodder crops of 1972 and 1973. The investigations were made on fresh red clover and on the same red clover after periods of storage of varying length. The red clover was stored in manilla bags in a silo among the ordinary silge fodder, use being of the "green solution method" (Farmos Oy). In the studies the estrogenic effect of the fodder was ascertained by means of bioassay, the criterion being the increase in murine uterine weight. The known plant estrogens were determined by thin layer chromatography and by liquid chromatography. The estrogenic effect of the red clover silage fodder of 1972 was greater in all the silage fodder samples than it was in the fresh red clover. The quantity of individual isoflavones and "transformed" estrogen too, was greater in many of the silage fodder samples than it was in the respective fresh red clover. The estrogenic effect of the silage fodder made from the red clover of 1973 varied considerably; in some samples it was greater but in most it was smaller than the estrogen effect of the fresh red clover. However, apart from a few exceptions, the quantity of individual isoflavones and of transformed estrogens was smaller than it was the fresh red clover.     

Utilization of grass silage by growing cattle: effect of a supplement containing ruminally protected amino acids.

Sixteen crossbred steers (278 +/- 4.9 kg) were used to determine the influence of supplemental ruminally protected lysine and methionine on performance of growing cattle fed grass silage. During the 154-d experiment, all steers were allowed ad libitum consumption of a good-quality grass silage during the first 70 d and of a lesser-quality silage during the remaining 84 d of the trial. The steers received a supplement of .5 kg/d of barley with or without a mixture of ruminally protected amino acid (RPAA) containing 8.2 g of lysine and 2.6 g of methionine. Compared with controls, steers supplemented with RPAA showed 16.3% improved (P less than .03) ADG (.92 vs 1.07 kg/d). Dry matter intake was not affected (P greater than .50) by treatment and averaged 2.03% BW across treatments. Supplementation with RPAA improved feed/gain by 13.6% (7.88 vs 6.81 for control and RPAA treatments, respectively, P less than .01). Plasma levels of methionine, lysine, arginine, and glutamic acid were higher (P less than .05) and of histidine were lower (P less than .001) when RPAA were fed. These results indicate that feeding RPAA can improve the performance of growing steers fed grass silages of varying qualities.     

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。