Model Analysis of Response of Pensacola Bahiagrass to Applied Nitrogen,Phosphorus, and Potassium. I. Seasonal Dry Matter

Abstract

Forage production is influenced by such factors as applied nutrients, water availability, and harvest interval (for perennials). Logistic models have been developed for response to single and multiple elements such as nitrogen (N), phosphorus (P), and potassium (K). This analysis focuses on response of Pensacola bahiagrass (Paspalum notatum Flügge) to applied N, P, and K. The multiple logistic model is shown to describe the data rather well. A step-wise procedure is outlined for parameter evaluation. It appears that the model is relatively free of bias. It is concluded that a factorial design of N × P × K = 3 × 3 × 3 is the minimum number of treatments required for the analysis. Plant nutrient uptake data would also enhance the value of the results.     

Evaluation of Diversity among North American Accessions of False Indigo (Amorpha fruticosa L.) for Forage and Biomass

False indigo (Amorpha fruticosa L.) is a perennial leguminous shrub native to North America. The species could potentially be used for livestock forage, biomass energy, reclamation of degraded environments, or as green manure. Future work with the species will depend upon knowledge of available accessions. Our objectives were to determine (1) the range of diversity among accessions, (2) the correlations among traits across locations, and (3) the distribution of variation among accessions. We studied 21 accessions grown at two locations and a subset of 15 accessions grown at a third location. We measured 47 morphological, agronomic, and phenological traits. All traits were influenced by accession in at least one location (p < 0.05). The mean dry matter (DM) biomass yield of accessions in August ranged from 53 to 1515 g plant⁻¹ and was correlated across locations. False indigo had a high second-year leaf concentration, averaging 660 g kg⁻¹ DM at one location in August. Forage quality of false indigo leaves was high, with average crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF) concentrations in July of 205, 226, and 235 g kg⁻¹, respectively. Accession means of forage quality traits were poorly correlated across locations, indicating that it would be difficult to improve forage quality through selection. Diversity among accessions was often related to geographic origin. The two southern accessions were distinct from all other accessions, indicating that accessions from distant geographic regions will likely contribute valuable diversity to a plant breeding program.     

Genetic diversity of the complex Paspalum notatum Flügge (Paniceae: Panicoideae)

The genus Paspalum L. comprises approximately 400 species worldwide and about 220 in Brazil. Paspalum is ecologically and economically important, and has been very useful as pasture and P. notatum Flügge (bahiagrass) is a valuable forage grass in the subtropics. This species consists of several sexual (diploid) and apomictic (tetraploid, ocasionally tri and pentaploids) biotypes. In this work, inter simple sequence repeats (ISSR) markers were used to assess the genetic variability of a bahiagrass (P. notatum) collection. Vegetative tissues of 95 bahiagrass accessions were obtained from various locations in South America (Brazil, Argentina and Uruguay). A total of 91 reproducible ISSR fragments were observed and 89 fragments (97.5% of the total observed) were polymorphic. Cluster analyses (UPGMA) were performed from the ISSR data set and the results illustrate the genetic relationships among the 95 accessions of P. notatum. A comparison among molecular, morphological and ploidy levels data were done. ISSR markers were effective in distinguishing the genotypes analyzed, and a wide variability was observed for this species. These results add new information regarding the genetic diversity in P. notatum, thus contributing toward the biological knowledge of this species, and providing with subsides for future plant breeding and conservation programs.     

Effects of pasture‐applied biosolids on forage and soil concentrations over a grazing season in north Florida. I. macrominerals,crude protein,and in vitro digestibility

Abstract

The rationale for this experiment was to determine forage nutrient concentrations as affected by biosolids fertilization. We studied the effects of single applications of two exceptional quality biosolids to bahiagrass (Paspalum notatum) pasture with regard to satisfying beef cattle nutrient requirements. Twenty‐five 0.8‐ha pastures were divided into five blocks. Two biosolids were applied as normal and double agronomic rates. The control plot received NH₄NO₃. Forages were analyzed for calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K), sodium (Na), crude protein (CP), and in vitro organic matter digestibility (IVOMD), and soils were analyzed for Mehlich I extractable Ca, P, Mg, and K. Single (agronomic or twice this) applications of biosolids to pastures had little effect on Ca, P, Na, and K forage concentrations, but forage Mg was elevated in several treatments late in the season. Crude protein concentrations were elevated above the control for all biosolids treatments late in the season, whereas only small differences were observed at early sampling times. Trends were similar for IVOMD. In general, all treatments were associated with soils with adequate Ca, P, and Mg concentrations, while soil K was uniformly low. In relation to grazing beef cattle requirements, all treatments resulted in generally adequate forage levels of Ca, P, Mg, K, CP, and IVOMD, however, Na (<0.06%) was deficient.     

Effect of Nitrogen Fertilizer Rate and Harvest Season on Forage Yield,Quality, and Macronutrient Concentrations in Midland Bermuda Grass

Bermuda grass [Cynodon dactylon (L.) Pers.] is a major forage for grazing and hay production in the southern United States. The objectives of this study were to determine effects of nitrogen (N) fertilization rate (0, 112, 224, 336, and 448 kg ha^?1), split spring and summer applications of N at the 224 and 448 kg ha^?1 rates, and harvest periods (spring and summer) on forage yield, crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), total digestible nutrients (TDN), and concentrations of phosphorus (P), potassium (K), magnesium (Mg), and calcium (Ca in Midland Bermuda grass. Data were collected from 2002 to 2008 as part of an ongoing, long-term soil fertility experiment in southern Oklahoma. Repeated measures analysis of these long-term data showed that forage yield responses to N rate varied with year and harvest time with up to 2.5-fold yield differences among years. Nitrogen fertilization increased CP, TDN, and macronutrient P and Mg and decreased ADF and NDF. Crude protein was increased by ≥50%, and ADF and NDF dropped by up to 25% with the greatest N rate. In general, split N applications did not affect forage yield but produced low-quality forage compared to single N application in spring. Split application of 448 kg N ha^?1 gave forage with CP, TDN, ADF, and NDF similar to the Bermuda grass receiving 336 or 448 kg N ha^?1 as a single application. Spring forage had better forage quality than summer harvests. While N fertilization increased forage Mg and P concentrations by more than 50% during both spring and summer, it had no effect or slight increased K and Ca concentrations. In the southern Great Plains, despite the weather-dependent variability in forage yield of Bermuda grass, N application increase forage quality.     

Agronomic comparison of six bermudagrasses from Southern United States with five tropical grasses in central Puerto Rico

The dry matter yield (DMY), in vitro organic matter digestibility (IVOMD) and crude protein (CP) content of eleven grasses were studied during the years 1992 to 1994 under mob grazing conditions. Offered and consumed dry forage do not differ significantly (P<0.05) among the highest yielding accessions Cynodon nlenfuensis PRPI 2341, Cynodon plectostachium PRPI 11487, and Cynodon dactylon cv. Tifton 85. However, the commercial Cynodon nlenfuensis PRPI 2341 was consistently the highest yielding accession both years. Among the other grasses, Digitaria eriantha showed the lowest levels of refused dry forage, thus presenting the best forage acceptability by grazing animals. Digitaria eriantha also showed the highest levels of IVOMD in both the short and the long day seasons. It is concluded that none of the evaluated Cynodon dactylon accessions from southern United Sates, nor the digitaria and brachiaria species adapted better than the commercial accession Cynodon nlenfuensis PRPI 2341. Warm‐season perennial grasses are grown extensively in the southeastern United States. Among the grasses, one of the most widely grown is from the species Cynodon dactylon, commonly named bermudagrass (Eichhorn, 1984). The choice of a bermudagrass cultivar for establishment of pastures is an important decision for cattlemen seeking high weight gains of stocker steers throughout the warm grazing season of the southern United States (Greene et al., 1989). Selection of improved bermudagrass hybrids has dramatically increased forage yield over that of common bermudagrass. Improved forage quality has also resulted in improved performance of grazing animals fed harvested hybrid bermudagrass forage (Gates et al., 1989). Reports on average daily weight gains (ADG) of yearling steers grazing different bermudagrass hybrids varied between 0.68 to 0.79 kg animal^‐1 day^‐1 during the summer season of southern Louisiana (Faw et al., 1986). Hill et al. (1993) in Tifton, GA, found yearling ADG of 0.67 and 0.65 kg animal^‐1 day^‐1 for the recent bermudagrass releases Tifton 85 and Tifton 78, respectively. Forage quality dry matter yield and grazing performance support the hypothesis that Tifton 85 will likely become an important hay and grazing forage for the southern United States. In Puerto Rico, Cynodon nlenfuensis PRPI 2341 (stargrass) is at present the grass cultivar most frequently grown on dairy farms (Ramos‐Santana and Randel, 1996). Yearly ADG of 0.59 kg animal^‐1 day^‐1 has been reported for young steers grazing stargrass in the humid tropical zone of Puerto Rico (Vicente‐Chandler et al., 1983). At Ona, FL, lower ADG of 0.54 kg has also been obtained with stargrass (Mislevy, 1989). The objective of this paper is to compare the agronomic performance (dry matter yield and quality) of six of the most outstanding bermudagrass hybrids from the southern United States, with five tropical grasses from the cynodon, brachiaria, and digitaria genera under the tropical conditions of central Puerto Rico.     

Variation of forage and extractable soil minerals over two grazing seasons in North Florida

Abstract

A two‐year experiment was conducted at a north Florida farm to evaluate the mineral status of bahiagrass forages and soils. Forage samples were collected every 28 d throughout the grazing season, and soils evaluated twice yearly. The minerals calcium (Ca), sodium (Na), copper (Cu), cobalt (Co), selenium (Se), and zinc (Zn) were uniformly below the dietary requirements for growing beef cattle in both years. Forage magnesium (Mg), phosphorus (P), potassium (K), crude protein (CP), and manganese (Mn) were generally adequate throughout the grazing season, with the exception of low P concentration at the end of the growing season for both years. Extractable soil concentrations of Ca, P, K, Mg and Zn were adequate but low in Cu. Although CP was adequate (>7.0%) throughout the grazing season, IVOMD values were relatively low. There was a general trend for forage P, K, and IVOMD to decrease (P<0.05) with time.     

Mineral Concentrations of Cool Season Pasture Forages in North Florida During Winter-Spring Grazing Season. I. Macrominerals and Forage Organic Constituents

Two experimental late fall-winter-spring grazing studies, each lasting two years, were conducted at the North Florida Research and Education Center (NFREC), Marianna, Florida to evaluate the organic constituents and macromineral concentrations of annual cool season pasture forages grazed by growing beef cattle. Eight 1.32 ha fenced pastures or paddocks were divided into two pasture land preparation/planting methods, four pastures for the sod seeding treatments and four for the prepared seedbed treatments. These pastures were planted with two different forage combinations: rye/oats mix with or without ryegrass for the first two years (Study 1), and oats with ryegrass or ryegrass only for the last two years (Study 2). Each of the four forage/land preparation combination treatments was assigned to two pastures each year, thereby giving two replicates per year. Forage samples were collected at the start of grazing and twice monthly thereafter until the end of grazing season for each year, pooled by month, and were analyzed for calcium (Ca), phosphorus (P), sodium (Na), potassium (K), magnesium (Mg), dry matter (DM) yield, crude protein (CP), and in vitro organic matter digestibility (IVOMD). Blood plasma samples were also collected from the tester cattle during the spring season of year 2 of Study 2 and were analyzed for Ca, P, and Mg. Month differences were observed in forage concentrations of P and K (P < 0.0001), and Mg (P < 0.05) in both studies, Ca (P < 0.01) in Study 1 only, and Na (P < 0.05) only in Study 2. Year affected P, K, and Mg concentrations in Study 1 and Ca, P, and Na concentrations in Study 2. In Study 2, forage type by month interactions on Ca, K, and Mg concentrations were noticed (P < 0.01). Forage Ca was lower (P < 0.05) than the critical level for all months from the oat plus ryegrass pastures, and for early winter months and late spring months from ryegrass only pasture. Forage Na concentrations were consistently low throughout the grazing season and unaffected by forage type or land cultivation methods used in both studies. Low Mg concentrations of both forage types in Study 2 (also with high K concentrations) were indicative of a potential risk of grass tetany (hypomagnesemia) for grazing ruminants. Forage DM yields were highly variable with fluctuations among the experimental months and were found to be highest in the spring months, with decreasing yields towards the end of the grazing season in both studies (P < 0.0001). The CP concentrations were greater than the required levels and both CP and IVOMD decreased gradually by month in both studies (P < 0.0001). Normal blood plasma concentrations of Ca and P obtained were indicative of a good overall status of these minerals in the animal's body. Plasma Mg concentrations were slightly above the critical level for cattle from both forage types. In summary, the macrominerals most likely to be deficient in North Florida during the cool season would be Ca, Na, and Mg. Special attention should be given to supplementation of Mg since forages reflected a marginal deficiency of this mineral and high K concentrations were found.     

YIELD AND MINERAL CONCENTRATIONS OF SOUTHEASTERN UNITED STATES OAT CULTIVARS USED FOR FORAGE

A shift in oat (Avena sativa L.) production from grain to forage (hay and grazing) is occurring in the southeastern USA. However, most available cultivars were developed for improved grain production, rather than forage yield. We field tested several standard and new oat releases over 2 years, using repeated clippings to determine forage yield, nutrient uptake, and the potential to match plant nutrients with cattle mineral dietary needs. There were no differences in total annual forage yield among the tested cultivars within years but there was a difference between years. Forage tissue phosphorus (P), magnesium (Mg), and calcium (Ca) were sufficient, potassium (K), sulfur (S), and manganese (Mn) were excessive, and iron (Fe), copper (Cu), and zinc (Zn) were occasionally or frequently deficient to meet daily cattle dietary mineral needs. Sulfur, Cu, Fe, Zn, and Mn may be the most challenging to regulate in U.S. Coastal Plain soils at concentrations that satisfy both, oat and cattle nutritional requirements.     

Soil fertility effects on growth and nutrient uptake of rhizoma peanut

Expansion of forage production acreage for rhizoma peanut (RP ‐ Arachis glabrata Benth.), a persistent perennial, warm‐season forage legume adapted to the Gulf Coast region of the southeastern United States, is limited primarily by establishment rate, often taking up to three years. The objective was to determine the effects of two divergent soil environments on the dry matter production and nutrient uptake of RP in the first year following establishment. Five Arachis genotypes, ‘Arbrook’, ‘Florigraze’, and experimental lines 423, 575, and 616, were established during March 1995 at Clinton and Olive Branch, LA. Soils were a Dexter silt loam (Ultic Hapludalf) and a Loring silt loam (Typic Fragiudalf, fine‐silty, mixed, thermic) with mean pH values of 6.8 and 4.7, respectively. Soils also differed for extractable potassium (K), sodium (Na), calcium (Ca), aluminum (Al), sulfur (S), copper (Cu), iron (Fe), manganese (Mn), and organic matter (OM). Tissue samples were taken at three week intervals in 1996 and yield and quality were evaluated at six week intervals. Locations differed significantly for dry matter production, crude protein (CP), neutral detergent fiber (NDF) and in vitro true digestibility (IVTD). Entries also differed within locations for yield, CP, NDF, acid detergent fiber (ADF), and IVTD. Tissue nitrogen (N), K, Ca, S, Mn, boron (B), and zinc (Zn) were significantly different between locations, but phosphorous (P), magnesium (Mg), Fe, Cu, and Al were not different. Yield and forage quality were both inversely correlated with pH and, with the exception of N, none of the other nutrients were low enough to account for the differences observed in growth between the two locations.     

Nitrogen application effects on forage sorghum production and nitrate concentration

Abstract

Forage sorghum (Sorghum bicolor (L.) Moench) is an important annual forage crop but prone to high nitrate concentration which can cause toxicity when fed to cattle (Bos taurus and Bos indicus). Two field experiments were conducted over six site-years across Kansas to determine the optimum nitrogen (N) rate for no-till forage sorghum dry matter (DM) yield and investigate the effect of N fertilization on sorghum forage nitrate content. A quadratic model described the relationship between sorghum DM and N rate across the combined site-years. Maximum DM yield of 6530?kg ha^?1 was produced with N application rate of 100?kg N ha^?1. The economic optimum N rate ranged from 55 to 70?kg N ha^?1 depending on sorghum hay price and N fertilizer costs. Crude protein concentration increased with N fertilizer application but N rates beyond 70?kg N ha^?1 resulted in forage nitrate concentrations greater than safe limit of 3000?mg kg^?1. Nitrogen uptake increased with N fertilizer application but nitrogen use efficiency and N recovery decreased with increasing N fertilizer rates. In conclusion, forage sorghum required 55–70?kg N ha^?1 to produce an economic optimum DM yields with safe nitrate concentration.     

Effect of applied nitrogen and harvest interval on nitrogen concentration in bahiagrass

Abstract

An equation was developed which relates average annual nitrogen concentration of Pensacola bahiagrass to applied nitrogen and harvest interval. The equation incorporates linear decrease with harvest interval (up to 7 weeks) and exponential increase with applied nitrogen. Regression analysis of field data from five studies in Georgia, Florida and Alabama allowed evaluation of the four coefficients in the equation. An attempt was made to interpret the significance of the coefficients. These results are relevant to forage production and environmental quality     

Land Application of Aluminum Water Treatment Residual: Aluminum Phytoavailability and Forage Yield

Negative impacts of land‐applied aluminum (Al)–rich water treatment residuals (WTRs), which have been suggested to improve soil phosphorus (P) sorption, could include excessive immobilization of plant‐available P and Al phytotoxicity. We studied the impacts of an Al‐rich WTRs on agronomic returns and plant Al concentrations in glasshouse and field studies. The glasshouse study was a 4 × 2 × 3 factorial experiment with one control in a randomized complete block design and three replicates. Four sources of P were each applied at two agronomic rate [44 kg P ha^?1, P‐based rate; and 179 kg plant‐available nitrogen (PAN) ha^?1, N‐based rate] to topsoil (0–15 cm) of a sandy, siliceous, hyperthermic Arenic Alaquods. Three WTR rates (0, 10, and 25 g kg^?1 oven‐dry‐weight basis) were further applied, whereas the control received neither P source nor WTRs. Bahiagrass (Paspalum notatum Fluggae), ryegrass (Lolium perenne L.), and a second bahiagrass crop were continuously grown in succession for 18 months. Applied WTRs increased soil Al but not plant Al concentrations (22–80 mg Al kg^?1), which fell within the normal concentration range for pasture plants. In the glasshouse, when WTRs were incorporated with the soil, bahiagrass dry matter (DM) accumulation was reduced, but ryegrass DM was not affected even at 25 g kg^?1 WTR. A 2‐year field study, with same treatments but two rates of WTRs (0 and 10 g kg^?1 WTR) surface applied to established bahiagrass on the same soil type (Spodosols) showed neither reduced yields nor increased plant Al phytoavailability in the WTR treatments. The studies show no increase in plant Al is associated with Al‐WTRs applied to reduce excess soil‐soluble P and P losses but plant DM accumulation may be reduced.     

Yield,in vitro digestibility,crude protein,and mineral concentration of eight Digitaria introductions in Puerto rico

Abstract

Dry matter (DM) yield, in vitro organic matter digestibility (IVOMD), crude protein (CP) and mineral composition of eight Digitaria accessions were compared between long‐ and short‐day seasons in the semiarid southern region of Puerto Rico and evaluated in relation to grazing ruminant requirements. Digitaria milanjiana 6416 was consistently among the highest DM yielding accessions in both seasons. The mean IVOMD was similar in both seasons for most accessions. Concentrations of CP, magnesium (Mg), copper (Cu), zinc (Zn), cobalt (Co), and selenium (Se) were below the recommended levels for grazing ruminants in both seasons. This study suggests the need for livestock mineral supplementation, even under conditions of high pasture fertilization (NPK) and forage‐growing conditions in the semiarid southern region of Puerto Rico.     

Responses of eastern gamagrass [Tripsacum dactyloides (L.) L.] forage quality to nitrogen application and harvest system

Eastern gamagrass is a warm-season perennial with good forage yield and quality, but both may be increased with nitrogen (N) fertilization. The effects of N and harvest management on neutral- and acid-detergent fibers (NDF and ADF), lignin, in vitro dry matter digestibility (IVDMD), and crude protein (CP) were studied. Nitrogen (0, 50, or 100 kg ha^?1) was applied by broadcasting or knife placement, and forage was harvested from 1- or 2-cut systems. Data were obtained during four years of N treatment, and three intervening years with no N treatment. Neutral- and acid-detergent fibers and lignin were usually lower, and IVDMD and CP were generally higher in the 2-cut than in the 1-cut system. Increasing N affected forage quality in minor ways, except for CP. When 100 kg ha^?1 was applied, CP was increased over no N by 0.14 in the 1-cut system and by 0.25 in cut 1 of the 2-cut system.     

Monthly variation of forage and soil minerals in central Florida. I. macro‐minerals

Abstract

A two‐year study was conducted to determine the macromineral status of cattle grazed forages, mostly bahiagrass, and soils in central Florida. Soil and forage samples were collected every month for two years. Month differences (P < 0.01) were observed in all forage macrominerals and in crude protein (CP) for both years. No month effect (P > 0.05) was observed in IVOMD level during year 1. Year effects (P < 0.05) were observed in calcium (Ca), sodium (Na) and CP. Concentrations below the critical level were observed in all macrominerals studied. Higher forage macro‐mineral concentrations were found during spring‐summer months. In general, higher (P < 0.05) soil aluminum (Al), Ca, magnesium (Mg), phosphorus (P), and organic matter (OM) were observed during fall‐winter months, while Na was higher in winter. Soil Ca and Mg were adequate and potassium (K), Na and P were deficient. Year 2 showed higher (P < 0.05) soil macromineral concentrations. Correlation coefficients (r >|0.5|, P < 0.05) were present between forage K and forage CP (r = 0.557) and between forage P and forage CP (r = 0.554). Low correlations were found between soil and forage macrominerals. Percentages of total forage samples with macromineral and CP concentrations below critical levels (in parentheses) and suggestive of deficiency were as follow: in forage, Ca (0.30 ppm), 21%; Mg (0.18 ppm), 34%; K (0.60 ppm), 47%; Na (0.06 ppm), 89%; P (0.25 ppm), 85%; and CP (7%), 18%.     

Response of tall fescue to fertilizer placement at different levels of phosphorus,potassium, and soil pH 1

Fertilizer application, particularly nitrogen (N), is important in cool‐season grass forage production. Subsurface (knife) placement of N often has resulted in higher forage yield and N uptake of tall fescue (Festuca arundinacea Schreb.) compared to surface‐broadcast fertilization, but further studies were needed to indicate whether soil pH, phosphorus (P), or potassium (K) modifies the response. Experiment I tested responses of forage yield and N and P concentration to N, P, and K amount and placement. Two types of fertilizer placement ‐ broadcast and knife ‐ were used with 13, 112, or 168 kg N; 0 or 19 kg P; and 0 or 37 kg K/ha in a factorial arrangement. Yields increased by 53% as N fertilization went from 13 to 112 kg/ha and by 69% as N increased from 13 to 168 kg N/ha. Forage yield was increased 26% from knife compared to broadcast fertilizer placement. P application increased forage production by 13%, but K application had no effect on yield. Forage N concentrations increased by 25% as N fertilization went from 13 to 112 kg/ha and by 38% as N increased from 13 to 168 kg N/ha. Effects of added P and fertilizer placement on N concentration often resulted in interactions among factors. Forage P generally was increased by added P, with some effects of interactions among N rate, P rate, and placement. In Experiment II, fescue responses to N placement were tested where different soil characteristics had been established by previous lime and fertility treatments. Forage yield, N concentration, and N uptake were highest where 9.36 Mg/ha of lime were applied as compared to the control. Previous fertility treatments had no significant (P<0.05) effect. When N was knifed, forage yield was related positively to available soil P but not to pH or K. Yield and forage N concentration and uptake were increased by 20, 11, and 33%, respectively, as a result of knife versus broadcast N application.     

食用菌栽培对棉籽壳营养价值及山羊瘤胃动态降解率的影响

为了研究4种食用菌栽培后对栽培基质棉籽壳的营养价值和山羊瘤胃动态降解率的影响,选用6只年龄(10月龄)、体重[(35.42±3.96)kg]接近并装有永久瘤胃瘘管的槐山羊羯羊,通过化学分析法测定了棉籽壳和4种菌糠的化学成分,并采用尼龙袋技术,分5批次测定了棉籽壳、平菇菌糠、木耳菌糠、金针菇菌糠和白灵菇菌糠瘤胃动态降解率。结果表明:(1)4种菌糠干物质(DM)和有机物(OM)含量分别比其栽培原料棉籽壳的含量降低13.09%~19.67%(P<0.01)和14.13%~39.52%(P<0.01),粗蛋白(CP)含量分别比棉籽壳提高40.20%~34.29%(P<0.01),中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量分别比棉籽壳降低3.07%~39.72%和17.80%~45.91%(P<0.01);(2)木耳菌糠、金针菇菌糠、白灵菇菌糠的DM和OM在瘤胃内的有效降解率和a+b值(快速降解部分和慢速降解部分之和)均极显著高于棉籽壳(P<0.01),平菇菌糠的DM和OM在瘤胃内的有效降解率显著高于棉籽壳(P<0.05);平菇菌糠、金针菇菌糠、白灵菇菌糠的CP在瘤胃内的有效降解率和a+b值均极显著高于棉籽壳(P<0.01);4种菌糠的NDF和ADF在瘤胃内的有效降解率分别比棉籽壳提高76.72%~702.63%(P<0.01)和137.41%~575.31%(P<0.01)。因此,在棉籽壳上栽培4种食用菌均能改善棉籽壳的营养价值和提高山羊瘤胃消化率,栽培食用菌后的菌糠更有利于作为反刍动物饲料进行利用。     

饲粮蛋白质水平对鹅生产性能及养分代谢率的影响

选取2 8日龄、体重相近的合浦灰鹅6 0只,随机分为3组,每组2 0只(1 0公,1 0母),饲粮(精料)粗蛋白质(CP)分别为12.50%(第1组),15.80%(第2组)和17.83%(第3组)。采用精料 青料(黑麦草等)混合方式饲喂,进行两阶段为期42 d的饲养试验。5周龄和9周龄时从饲养试验3个组中各选取4只体重接近的试鹅,测定鹅对饲粮(精料 青料)养分的代谢率。结果表明:(1)生长前期(28~49日龄),第2组日增重较高,但组间差异不显著;饲粮粗脂肪(EE)、中性洗涤纤维(NDF)、半纤维素和无氮浸出物(NFE)的代谢率显著高于其他两组(P<0.05)。(2)生长后期(50~70日龄)第1组日增重较高,但组间差异不显著;干物质(DM)、CP、EE的代谢率显著高于其他两组(P<0.05);粗纤维(CF)代谢率显著高于第2组(P<0.05)而与第3组无显著差异。(3)血清尿素氮含量随饲粮CP水平的降低而下降(P<0.05);血清转氨酶活性、脂类和脂蛋白含量等组间无显著差异;(4)饲粮粗蛋白质水平对肉鹅屠宰性能无显著影响。     

高水分苜蓿干草捆防霉复合添加剂配方筛选

为有效保存高品质苜蓿干草探索一种新型防霉复合添加剂,该试验选择5个主要防霉及载体成分,每个成分设置4个不同浓度水平,利用正交试验设计L16(45)进行防霉复合添加剂配方优化方案筛选。结果表明,硫酸钠和钠基膨润土为影响干草保存品质的2个主要影响因子;硫酸钾对提高干物质(dry matter,DM)和可溶性糖(water soluble carbohydrate,WSC),降低中洗纤维(neutral detergent fiber,NDF)和酸洗纤维(acid detergent fiber,ADF)效果最好;钠基膨润土明显改善了干草中粗蛋白(crude protein,CP)质量分数,是干草中CP、非蛋白氮(non-protein nitrogen,NPN)、灰分Ash含量的主要影响因子;而亚硫酸钾和a-淀粉酶对干草品质的改善作用相对次之;正交表试验设计结果分析表明,优化复合添加剂最优组合为硫酸钠35.51%,亚硫酸钾32.78%,硫酸钾1.64%,a-淀粉酶0.03%,钠基膨润土21.85%,葡萄糖8.19%。其添加后能够维持或提高高水分苜蓿干草贮藏后的干物质、粗蛋白、可溶性糖和灰分的含量,同时能够降低干草中中性洗涤纤维和非蛋白氮的含量。该组合添加剂在干草中的添加量为每吨干草添加1.15kg,应用成本为每吨干草11.5元。