Effects of grass hay proportion in a corn silage‐based diet on rumen digesta kinetics and digestibility in dairy cows

In this study, we aimed to evaluate the effects of six levels of orchardgrass hay (GH) proportion (0%, 10%, 20%, 30%, 40% or 50% of dry matter) in finely chopped corn silage (CS)‐based diets on digesta kinetics of CS and GH in the rumen. Six non‐lactating, rumen‐cannulated Holstein cows were used in a 6 × 6 Latin square design. Ruminal digesta kinetics was measured by ruminal dosing of feed particle markers (dysprosium for CS, erbium for GH) followed by fecal sampling. The increase of GH proportion had a quadratic effect (P < 0.01) on total tract digestibility of neutral detergent fiber (NDF) and acid detergent fiber. The proportion of GH did not affect the particle size distribution of rumen digesta, total weight of dry matter or NDF in the rumen. The rates of large particle size reduction in the rumen for CS tended to increase linearly with increasing GH proportion (P = 0.077). A quadratic effect (P < 0.05) was found with increasing the GH proportion for the ruminal passage rate of small GH particles, but not for CS particles. The results suggested that associative effects between CS and GH could be generated on rumen digesta kinetics when cows were fed a CS‐based diet with an increased proportion of GH.     

Effect of salinomycin level on nutrient digestibility and ruminal characteristics of sheep and feedlot performance of cattle

A sheep digestion trial and two feedlot trials with cattle were conducted to study effects of an ionophore, salinomycin, on nutrient digestibility, ruminal metabolism and cattle performance. In trial 1, addition of salinomycin at 5.5, 11 or 22 ppm to 60% concentrate diets fed to ruminal-cannulated rams had no effect (P greater than .05) on apparent digestibility of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF) or starch in comparison with control diets. Apparent nitrogen (N) digestibility was increased (P less than .05) in animals fed salinomycin. Salinomycin did not affect total volatile fatty acid (VFA) concentrations in the rumen, but resulted in a linear (P less than .05) increase in molar proportion of propionate and a linear (P less than .05) decrease in molar proportions of acetate and butyrate and in acetate:propionate ratios. Shifts in VFA proportions were fully expressed within 4 d after salinomycin was added to the diet. In trial 2, salinomycin was added at 5.5, 11, 22 or 33 ppm to 85% concentrate diets fed to finishing steers. Salinomycin level had a quadratic effect (P less than .05) on daily weight gain and resulted in a quadratic (P less than .05) decrease in feed intake with a resultant average improvement of 10.3% in feed efficiency. Salinomycin (5.5, 11, 16.5 or 22 ppm) and monensin (22 ppm) were added to 90% concentrate diets in trial 3 and produced increased rates of gain without affecting feed intake.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of limestone level in high concentrate and high roughage diets on site and extent of digestion in lambs

Two digestion and slaughter trials were conducted to evaluate the influence of limestone level on site and extent of digestion and rumen fermentation in lambs. In trial 1, 11 wether lambs (avg wt 40.7 kg) were fed 75% concentrate diets supplemented with .6, 1.5 or 3.0% limestone (.6,1.2,1.7% dietary Ca, respectively) in a completely randomized design. Dry matter intake increased linearly (P less than .10) with limestone level; therefore, other data were analyzed with dry matter intake as a covariate. Total tract organic matter digestion decreased linearly (P less than .05) with increasing limestone but dry matter and fiber digestion were not affected by limestone. Ruminal digestion of dry matter and organic matter declined linearly (P less than .05) with increasing limestone. Ruminal neutral detergent fiber (NDF) digestion was higher with the 1.5 than the .6 and 3.0% limestone diets (quadratic effect, P less than .05) but ruminal digestion of other fiber components was not affected by limestone. Ruminal volatile fatty acids were not affected by limestone level; however, rumen ammonia concentrations decreased linearly (P less than .05) with increasing limestone level. In trial 2, 12 wether lambs (avg wt 43.3 kg) were fed a 35% concentrate diet with .1, 1.5 or 3.0% limestone (.5, 1.2 and 1.6% dietary Ca, respectively) in a completely randomized design. Dry matter intake was not affected by limestone level, but digestibility of dry matter, organic matter and starch (P less than .10), energy, crude protein, acid detergent fiber (ADF) and cellulose (P less than .05) responded quadratically to limestone level, with increases at the 1.5% limestone level. Ruminal dry and organic matter (P less than .05), NDF (P less than .10), ADF (P less than .01), cellulose (P less than .05) and starch (P less than .05) digestion responded quadratically to limestone level with higher values at the 1.5% limestone level. Proportions of ruminal propionate increased linearly (P less than .01) with increasing limestone level and acetate: propionate ratio declined linearly (P less than .01) with limestone level.     

甘蔗品种及收割期对生长期肉牛采食量和瘤胃参数的影响

本试验旨在研究甘蔗青贮饲料的基因型和成熟期对肉牛瘤胃纤维消化率、采食量、瘤胃发酵、瘤胃动力学和瘤胃细菌数量的影响。试验采用2×2因子设计,即两个基因型(高和低中性洗涤纤维消化率)和2个收割期(早熟和晚熟)。试验日粮以40%青贮甘蔗饲料为试验料。结果:饲喂早熟甘蔗青贮饲料时干物质采食量较大,但仅表现在低中性洗涤纤维消化率基因型(P<0.05)。早熟甘蔗日粮较晚熟甘蔗日粮显著提高了中性洗涤纤维摄入量(P<0.05)。饲喂低中性洗涤纤维基因型饲粮时,瘤胃池干物质、中性洗涤纤维和不可消化中性洗涤纤维含量更高(P<0.05)。饲喂高中性洗涤纤维消化率品种的青贮甘蔗时,中性洗涤纤维和不可消化中性洗涤纤维过瘤胃速率更高(P<0.05)。饲喂早熟青贮甘蔗饲料的肉牛瘤胃pH较大,但表现在高中性洗涤纤维消化率品种组(P<0.05)。饲喂早熟青贮甘蔗饲料时,低中性洗涤纤维消化率品种组肉牛瘤胃短链脂肪酸总浓度较高(P<0.05)。晚熟期青贮甘蔗较早熟期显著提高了埃氏巨球型菌相对含量(P<0.05)。综上所述,采用高中性洗涤纤维消化率品种的青贮甘蔗饲喂生长期肉牛,可以通过更快的纤维过瘤胃速率和纤维周转对瘤胃池产生积极影响,这可能有利于提高采食量。     

Influence of varying levels of dietary cation anion difference on ruminal characteristics,nitrogen metabolism and in situ digestion kinetics in buffalo bulls

This study was conducted to examine the influence of varying dietary cation anion difference (DCAD) on nutrient intake, digestibility, ruminal characteristics, blood acid base status and in situ digestion kinetics in Nili Ravi buffalo bulls. Four iso‐nitrogenous and iso‐caloric diets having ?110, +110, +220 and +330 mEq/kg dry matter (DM) DCAD were formulated which were represented by A (anionic), LC (low cationic), MC (medium cationic) and HC (high cationic), respectively. These diets were used in four ruminally cannulated Nili Ravi buffalo bulls in a 4 × 4 Latin Square Design. Improved nutrient intake was recorded at high DCAD levels while digestibility remained unaffected. Ruminal ammonia nitrogen, rumen pH, acetate and acetate : propionate ratio were higher in buffalo bulls fed MC and HC diets than those fed A and LC diets. Blood pH and HCO₃^‐ also tended to increase as DCAD level was increased in the diet. Serum Ca and Cl concentrations were higher in bulls fed A and LC diets whereas serum Mg, P and S remained unaffected. Urine pH increased with increasing DCAD level. Nitrogen intake and blood urea nitrogen concentrations were also higher in bulls fed MC and HC diets. There was a consistent increase in ruminal DM and neutral detergent fiber degradability, rate of disappearance and extent of digestion at high DCAD levels in the diet. However, lag time decreased at high DCAD level. This study indicated that buffalo bulls fed MC and HC diets improved feed intake, ruminal characteristics and digestion kinetics.     

Effects of wood kraft pulp feeding on feed digestibility and rumen fermentation of Japanese Black steer in the middle fattening stage

We investigated the effects of wood kraft pulp (KP) feeding on feed digestibility and rumen fermentation of Japanese Black (JB) steer in the middle fattening stage. The feeding experiment was carried out a replicated 3 × 3 Latin square design using six JB steers (16.2 ± 0.8 months of age). Steers were fed rice straw and three concentrated feeds: commercial formula feed (control), formula feed containing 7.5% KP on a dry matter (DM) basis (7.5% KP), and formula feed containing 15% KP on a DM basis (15% KP). Feed digestibility and rumen fermentation parameters were recorded for 3 days during the measurement period, after an adaptation phase of 11 days. There was no significant difference in DM intake per day among diets. A slightly higher digestibility of neutral detergent fiber was observed in steers fed 15% KP, compared with those fed other diets (P = 0.059). The butyric acid ratio in rumen fluid was higher in steers fed KP diets than in steers fed control (P = 0.083). The average ruminal pH was unaffected by KP diets. This study suggests that replacing 15% of concentrated feed with KP has little effect on feed digestibility and rumen fermentation in JB fattening steer.     

Effect of replacing alfalfa hay with a mixture of cassava foliage silage and sweet potato vine silage on ruminal and intestinal digestion in sheep

This study aimed to investigate the effects of replacing alfalfa hay (AH) with a mixture of cassava foliage silage and sweet potato vine silage (CSP) (1:1 on a dry matter (DM) basis) on ruminal and intestinal nutrient digestion in sheep. Four wethers were fed a control diet containing 35% of AH and two treatment diets containing 15% and 30% of the CSP as substitute for AH at 1.5 times the metabolizable energy required for maintenance. Replacing AH with the CSP silage did not affect DM intake, whereas it linearly increased (P < 0.05) the intake of ether extract and acid detergent insoluble nitrogen (ADIN). Increasing the CSP substitution linearly decreased (P < 0.05) ruminal DM and neutral detergent fiber (aNDFom) digestibility; however, it did not affect total tract aNDFom digestibility. The CSP substitution did not affect nitrogen (N) intake and duodenal total N flow, whereas it linearly increased duodenal ADIN flow (P < 0.01) and decreased ruminal ammonia‐N concentration (P < 0.01), and intestinal (P = 0.08) and total N digestibility (P < 0.01). These results indicate that replacing AH with the CSP reduced the ruminal N degradation as well as the digestion of ruminal aNDFom and intestinal N.     

Effects of degree of fat saturation on fiber digestion and microbial protein synthesis when diets are fed twelve times daily

Three Holstein heifers and one nonlactating cow, fitted with ruminal and duodenal cannulas, were arranged in a 4 x 4 Latin square design to determine the effects of degree of fat saturation on ruminal neutral detergent fiber digestion and microbial protein synthesis and to determine whether changes in the efficiency of microbial protein synthesis were related to protozoal populations in the rumen. Corn silage-based diets contained no added fat or 4.85% of diet dry matter as partially hydrogenated tallow, tallow, or animal-vegetable fat. Iodine values of fat sources were 12.8, 50.6, and 109.7 for partially hydrogenated tallow, tallow, and animal-vegetable fat, respectively. Cattle were fed every 2 h and consumed 1.5% of body weight as dry matter daily. Ruminal neutral detergent fiber digestibility was decreased by added fat but was not affected by increasing iodine value. Flows of microbial N and non-NH3-nonmicrobial N to the duodenum were not affected by treatment. Ruminal protozoa concentration decreased linearly as the iodine value of fats increased. The efficiency of microbial protein synthesis was increased and protozoa concentrations tended to decrease when fat was fed. Decreased ruminal protozoa concentration may have decreased intraruminal N recycling. Biohydrogenation of added fat may result in a low ruminal concentration of unsaturated fatty acids when cows are fed frequently, reducing the negative effects of unsaturated fat sources on ruminal neutral detergent fiber digestibility. Protozoa were inhibited by unsaturated fat, but it is not clear if biohydrogenation and frequent feeding lessened inhibition.     

Characterization of in situ nitrogen and fiber digestion and bacterial nitrogen contamination of hay crop forages preserved at different dry matter percentages

Alfalfa, red clover, orchardgrass and timothy were harvested in the vegetative stage, wilted and stored as hay, or ensiled in small batch silos (20 kg) at 60, 40 or 20% (direct cut) dry matter and were analyzed for compositional differences. A ruminally cannulated lactating cow, consuming 50% of her dry matter intake from hay crop silage, was used to measure in situ dry matter, N, neutral detergent fiber and acid detergent fiber disappearance. Diaminopimelic acid was used as a bacterial marker to correct for bacterial N contamination for in situ residual N. Fibrous components tended to become concentrated as percent dry matter at preservation decreased, presumably associated with leaching of water solubles during storage. For most forages, as dry matter percentage of preservation decreased, water soluble dry matter and N increased, with a concomitant increase of ruminally nondigested dry matter. Specific trends in coefficients of digestion associated with forage type or preservation dry matter percentage were not observed for dry matter, N, neutral detergent fiber or acid detergent fiber. Correction for contamination by bacterial N decreased lag time in digestion and altered rates of N digestion compared with noncorrected rates. Linear and quadratic bacterial N contamination profiles were observed with time of ruminal incubation. Rate of digestion of N was highly correlated with fibrous component concentration, and to a lesser extent to rate of neutral and acid detergent fiber digestion. Dry matter percentage at preservation had a variable effect on ruminal digestion rate of dry matter and N, which varied with forage type and had no effect on neutral detergent and acid detergent fiber digestion rates. Correction for bacterial N contamination should be considered when establishing N digestion rates for forage by the in situ technique.     

Effect of Fusarium toxin-contaminated triticale and forage-to-concentrate ratio on fermentation and microbial protein synthesis in the rumen

In this study, the effect of Fusarium toxin-contaminated triticale (FUS) at high (60%) and low (30%) concentrate proportion in ruminant rations on ruminal fermentation, microbial protein synthesis and digestibility was investigated, using in vivo and in vitro methods. Significant effects of the forage-to-concentrate ratio on ruminal degradation and digestibility of crude nutrients and detergent fibre fractions as well as on the pH value and the concentration of short chain fatty acids (SCFA) in rumen fluid were found. The production of SCFA was affected, and the degradation of crude fibre and neutral detergent fibre in the rumen was reduced by the inclusion of FUS at high concentrate proportion. The efficiency of microbial crude protein synthesis was higher in diets with 60% than in diets with 30% concentrates, but was impaired in the presence of FUS in vitro at the high concentrate level. Marginal effects of FUS on the amino acid pattern of microbial protein were detected. It was concluded that the use of FUS in high concentrate diets can influence ruminal fermentation and microbial protein synthesis at a dietary deoxynivalenol concentration below 5 mg/kg dry matter.     

不同CBI日粮对牦牛瘤胃发酵参数、血清生化指标和养分消化率的影响

本试验旨在探究不同碳水化合物平衡指数(Carbohydrate balance index，CBI)日粮对牦牛瘤胃发酵参数、血清生化指标和养分消化率的影响，选取3种不同CBI(1.17，2.45，5.67)日粮，采用3×3拉丁方试验设计，通过一系列指标测定，明确牦牛最优日粮CBI水平。结果表明：不同CBI牦牛日粮瘤胃发酵参数均不显著；CBI=1.17与CBI=5.67牦牛日粮的白蛋白/球蛋白差异不显著，但均显著高于CBI=2.45的牦牛日粮(P<0.05)；CBI=2.45牦牛日粮干物质消化率、蛋白质消化率显著高于CBI=1.17和CBI=5.67(P<0.05)；CBI=2.45与CBI=5.67牦牛日粮的中性洗涤纤维消化率差异不显著，但均显著高于CBI=1.17(P<0.05)。综上所述：牦牛日粮的CBI=2.45更有利于其瘤胃发酵和养分消化利用。     

Effects of soybean meal supplementation on ruminal kinetics of feed particle size reduction and passage in dairy cows fed rice straw

Six ruminal-cannulated nonlactating Holstein Friesian cows (mean body weight:660 ± 42.9 kg) were used to investigate the effect of soybean meal (SBM) supplementation on voluntary rice straw (RS) intake, feed particle size reduction, and passage kinetics in the rumen. They were allocated to two dietary treatments: RS alone or RS supplemented with SBM. Voluntary dry matter intake of RS and total tract fiber digestibility was increased by SBM supplementation (p < 0.05). Supplementation with SBM decreased rumination time per dietary dry matter (DM) and neutral detergent fiber (NDFom) intake (p < 0.01). Particle size distribution in the rumen and total ruminal NDFom digesta weights were not affected by SBM supplementation. However, the disappearance rates of total digesta and large and small particles from the rumen were increased by SBM supplementation (p < 0.01). Moreover, SBM supplementation increased the rate of size reduction in ruminal particles (p < 0.05). In situ disappearance of DM and NDFom of RS in the rumen was greater in SBM-supplemented cows than in nonsupplemented cows (p < 0.05). This study clearly showed that increased ruminal RS particle size reduction, passage, and fermentation due to SBM supplementation accelerated the RS particle clearance from the rumen and resulted in increased voluntary RS intake of dairy cows.     

Evaluation of alfalfa-corn cob associative action. III. The effect of mechanically separated alfalfa fractions on intake, digestibility and ruminal characteristics of ammonia-treated corn cob diets fed to sheep

The influence of mechanically separated alfalfa fractions on intake, digestibility and rate of ruminal passage was investigated using 48 lambs (32 kg) in a digestion trial. Whole plant pre-bloom alfalfa (25% crude protein) or fractions (presscake, dehydrated presscake, protein coagulum, dehydrated protein coagulum, whole juice or deproteinized juice) were added to a 3% ammonia (NH3)-treated corn cob negative control diet at levels equal to 20% wholeplant alfalfa dry matter (DM); eight treatments, six lambs/treatment. Ad libitum intake was greater (P less than .05) for alfalfa fiber (presscake) or juice supplemented diets compared with 20% direct cut alfalfa. Dry matter intake, digestibility of DM and cell walls, and rate of passage were highly correlated when diets were fed ad libitum. At equal DM intakes, dehydrated vs wet presscake increased (P less than .05) DM and cell wall digestibility. Heating of the protein may have reduced degradation rate and consequently a slower release of nutrients for microorganisms in the rumen. Whole vs deproteinized juice increased digestibility of cob DM (P = .11) and cell walls (P = .13), suggesting a response to level of degradable alpha-amino N. Whole and deproteinized juice increased cell wall digestibility compared with the negative control by 23.0 and 18.5 percentage units, respectively, suggesting that degradable alpha amino-N and cell solubles or other nutrients interacted to maximize microbial fiber digestion. Total and branch-chain volatile fatty acids measured at 6, 12 and 18 h post-feeding were highly correlated with nutrient digestibility. Ruminal NH3-N measured at 18 h was negatively correlated with dry matter (r = -.74) and cell wall (r = -.72) digestibility, showing that alfalfa supplies nutrients required by ruminal microorganisms for NH3 assimilation and fiber digestion. The mode of alfalfa associative action in high fiber diets is in supplying ruminal microorganisms with degradable protein and (or) other nutrients, rather than altering ruminal retention time.     

Associative effects of sorghum silage and sorghum grain diets

A metabolism trial was conducted to quantitate associative effects between sorghum silage and sorghum grain, and to identify responsible factors. Diets were formulated by mixing ground sorghum grain (0, 15, 30, 45 and 60% of diet dry matter) with sorghum silage and were adjusted to 15.0% crude protein with soybean meal. Cannulated Beefmaster-cross steers (300 kg) were adapted to diets for 14 d followed by 5 d of fecal collection during which digestibility of components was determined. Intake of digestible dry matter and digestibilities of dry matter and neutral detergent fiber increased with increases in diet grain content (linear effect: P less than .01, P less than .01, P less than .05, respectively; quadratic effect: P less than .05, P less than .005, P less than .06, respectively). Digestibilities of starch, crude protein and hemicellulose were not significantly affected by grain level. Ruminal pH averaged 6.0 and was not significantly affected by grain level or time of sampling. Ruminal in situ digestion of neutral detergent fiber and acid detergent fiber at 48 h decreased (linear contrast, P less than .001) with increasing grain content. Rate of passage of liquid digesta was not affected by grain level in the diet. The rate of passage of particulate digesta decreased linearly (P less than .005, orthogonal contrast) with increasing levels of grain. Low levels of sorghum grain (15 and 30%) improved digestibility and intake of digestible dry matter of sorghum silage-based diets, whereas higher rates of grain supplementation (45 and 60%) did not result in further improvement.     

Effect of Mediterranean saltbush (Atriplex halimus) ensilaging with two developed enzyme cocktails on feed intake,nutrient digestibility and ruminal fermentation in sheep

The aim of this study was to assess the effects of feeding Atriplex halimus (AH) silage treated with two developed enzyme cocktails to sheep on feed intake, nutrient digestibility and ruminal fermentation. The AH silage was treated without or with 2 L of ZAD1^® or ZAD2^®/1000 kg with 5% molasses and ensiled for 30 days. Barley grain (300 g/head/day) was fed as an energy supplement once daily at 10.00 hours and AH silage with or without enzyme treatment was offered ad libitum to animals twice daily at 09.00 and 16.00 hours. Sheep were fed on four experimental forage diets comprised of AH silage and barley (D1), AH silage treated with ZAD1^® and barley (D2), AH silage treated with ZAD2^® and barley (D3) and AH silage treated with a combination of ZAD1^® and ZAD2^® (1:1) and barley (D4). Ensiling AH with enzymes reduced its contents of neutral detergent fiber and acid detergent fiber. The dry matter intake of AH of D2, D3 and D4 decreased (P < 0.001) as compared to D1. However, enzyme‐treated diets had greater total digestible nutrients intake (P < 0.001) as compared to D1. The nutrients digestibility for D2, D3 and D4 were higher than those for D1 (P < 0.001), and were higher for D3 as compared to both D2 and D4. Sheep fed on D3 had highest (P < 0.001) ruminal total volatile fatty acids concentration, ammonia nitrogen concentration and microbial protein yield. It could be concluded that AH silage treated with ZAD1^® or ZAD2^® improved digestibility and rumen fermentation in sheep.     

平菇处理水稻秸秆在乳山羊上的应用潜力

文章旨在评估用平菇和水稻秸秆混合培养的饲料原料替代常规牧草资源苜蓿草对乳山羊泌乳性能、养分消化、瘤胃发酵及乳成分的影响。试验选择产后5?d,平均体重为（24.21±0.23）kg的泌乳山羊36头,随机分为3组,每组4个重复,每个重复3头。对照组饲喂60%浓缩料+40%苜蓿草,T1和T2组用40%和80%平菇发酵水稻秸秆替代苜蓿草,试验为期4周。结果：对照组乳山羊牧草采食量较T2组显著提高了10.74%（P＜0.05）,T1组干物质和中性洗涤纤维表观消化率分别较对照组显著提高了7.49%和7.23%（P＜0.05）,而对照组有机物、粗蛋白质表观消化率分别较T2组显著提高了14.71%和13.44%（P＜0.05）。对照组血清球蛋白、肌酸酐、葡萄糖和胆固醇浓度最高（P＜0.05）,而T1组血清白蛋白浓度最高（P＜0.05）。处理组瘤胃pH较对照组显著提高了2.94%和3.10%（P＜0.05）。对照组瘤胃挥发性脂肪酸、氨氮、总氮和非蛋白氮浓度均显著高于处理组（P＜0.05）。T2组乳中脂肪含量较对照组显著提高了13.62%（P＜0.05）,对照组与T1组乳山羊的饲料效率（能量校正乳/采食量）较T2组显著提高了32.29%和36.46%（P＜0.05）。结论：乳山羊日粮中用40%平菇发酵水稻秸秆可以提高干物质和中性洗涤纤维表观消化率,改善瘤胃微生物蛋蛋白的合成。 [关键词]平菇|水稻秸秆|乳山羊     

Replacement of wheat bran with spineless cactus (Opuntia ficus indica Mill cv Gigante) and urea in the diets of Holstein x Gyr heifers

The aim of this study was to evaluate the replacement effect of wheat bran with spineless cactus and urea in heifers. Twenty-four heifers with an average initial weight of 185?±?13 kg were used in this experiment. Four levels of spineless cactus corrected with urea and ammonium sulfate (9:1) were studied: 0, 33, 66, and 100 % replacement with wheat bran. Samples of feed, orts, and feces were analyzed to estimate the intake and digestibility of dry matter (DM) and nutrients. Indigestible neutral detergent fiber was used as an internal marker. The experiment was conducted in a completely randomized design. Dry matter, neutral detergent fiber, and total digestible nutrient intake demonstrated a quadratic effect (P?P?P?相似文献   

葡萄渣单宁对绵羊养分消化代谢及瘤胃发酵的影响

选用4只体重28 kg左右且安装永久瘤胃瘘管羯羊[萨福克(Suffolk)♂×小尾寒羊(small tail Han-yang)♀],采用4×4拉丁方试验设计,通过消化代谢试验,研究饲料中不同含量葡萄渣单宁对绵羊养分消化代谢及瘤胃发酵的影响。试验共设4个处理,葡萄渣缩合单宁含量分别为0.00,0.85,1.70和2.25 g/kg DM。结果表明,葡萄渣单宁对绵羊干物质、有机物、中性洗涤纤维、酸性洗涤纤维、钙和磷的表观消化率没有产生显著影响(P>0.05),但显著提高绵羊氮表观消化率和存留率(P<0.05);显著降低绵羊瘤胃液总氮和蛋白氮浓度而显著提高尿素氮浓度(P<0.05),对绵羊瘤胃液氨氮浓度没有产生显著的影响(P>0.05);显著提高绵羊瘤胃液丙酸摩尔比而显著降低丁酸摩尔比和乙丙比(P<0.05),对绵羊瘤胃液pH、总挥发性脂肪酸浓度和乙酸及其他酸摩尔比没有产生显著的影响(P>0.05)。此外,试验结果表明饲料中添加2.25 g/kg DM含量的葡萄渣单宁,能够提高绵羊对饲料蛋白质的利用率。     

饲料来源对育肥湖羊生产性能、养分消化及瘤胃微生物组成的影响

为评价日粮粗饲料来源对育肥湖羊生产性能、养分消化及瘤胃微生物组成的影响。选择60日龄健康湖羊公羔(22.9±1.2) kg 120只,根据体重相近原则随机分成4组,每组5个重复,每个重复6只羊,分别以玉米秸秆(CS)、玉米芯(CC)、葵花籽壳(SH)和油菜秸秆(RS)作为粗饲料来源,添加比例均为20%,4组精料配比一致,预试期7 d,正试期70 d。在饲喂的49~55 d,每组选择5只羊采用全收粪法进行消化代谢试验,测定干物质(DM)、有机物质(OM)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和氮(N)的表观消化率。试验结束后,每组选择15只羊进行屠宰,采集瘤胃内容物,提取瘤胃微生物DNA,对瘤胃细菌进行绝对定量。结果显示:1)CS组湖羊干物质采食量显著高于其他3组(P<0.05),且末体重和平均日增重显著高于RS组(P<0.05),其他组间差异不显著(P>0.05)。2)CS和CC组湖羊DM和ADF消化率显著高于RS组(P<0.05),且其OM和NDF消化率显著高于SH组和RS组(P<0.05);SH组湖羊N消化率显著高于RS组,其ADF消化率与其他3组湖羊差异均不显著(P>0.05)。3)CS组和CC组湖羊瘤胃中白色瘤胃球菌和普雷沃氏菌数量均显著高于RS组(P<0.05),而SH组湖羊瘤胃中两种细菌的数量与其他3组湖羊均无显著差异(P>0.05),CS组和CC组湖羊瘤胃中黄色瘤胃球菌和产琥珀酸丝状杆菌数量均显著高于SH组和RS组(P<0.05),4组湖羊瘤胃中反刍兽新月单胞菌数量差异不显著(P>0.05)。结果表明:相较于葵花籽壳组日粮和油菜秸秆组日粮,玉米秸秆组和玉米芯组日粮不仅可以确保育肥湖羊的生产性能,并且有利于纤维分解菌的生存,可促进纤维素在瘤胃中的降解。