Thesis (M.Sc. (Agriculture)) --University of Limpopo, 2018 / Dry bean is one of the most important cash crops and source of protein for small holder farmers. Low yields of dry bean are often reported to be associated with lack of inoculation (Arbuscular mycorrihizal fungi) of seeds prior to planting. Soil phosphorus (P) unavailability is one of the major factors limiting yield of dry bean. Field and Greenhouse experiments were conducted to investigate the response of dry bean cultivars to inoculation and phosphorus application under dry land farming conditions at the Syferkuil experimental farm of University of Limpopo. Both greenhouse and field experiments were carried out as a split-split plot arrangement in randomised complete block design with four replications. Main plot treatment comprised of two dry bean cultivars VIZ, red speckled bean and small white haricot. Arbuscular mycorrhizal fungi inoculation levels (inoculated and uninoculated) were assigned in the sub-plot whilst the sub-sub plot was applied with five phosphorus rates at 0, 20; 40; 60 and 80 kg/ ha using single superphosphate (10.5 % P). The data collected were subjected to analysis of variance using statistical software (ANOVA) STATISTIX 10.0.Dry bean cultivars (red speckled bean and small white haricot bean) were evaluated in a field experiment for their growth, nodulation and yield responses to AM fungi inoculation and different rates of P fertiliser. The results revealed that the red speckled bean had higher number of nodules (45 %), stem diameter 26.96 cm and higher leaf area of 21.05 cm2 as compared to small white haricot bean. The application of P at the rate of 40 kg/ha produced higher grain yield of 743.47 kg/ha as compared to small white haricot bean with 572 kg/ha. The growth parameters such as yield, soil chemical and biological properties did not significantly respond to inoculation (P≤0.05). Red speckled bean and small white haricot bean were evaluated in greenhouse experiment for their growth and nodulation on inoculation and phosphorus fertilizer treatment In the greenhouse experiment phosphorus fertilizer rate showed significant effect on chlorophyll content, leaf fresh and dry weight. The dry bean cultivars were found to be significant to number of nodules, plant vigour and root dry weight. The red speckled bean showed higher growth parameters as compared to small white haricot bean. The application of Arbuscular mycorrhizal fungi (AM fungi) at varying rates did not have any significant influence on all parameters measured in the experiment on both trials. The study needs to be repeated after 4 to 5 years. The findings of this study concluded that P should be applied at the rate of 40 kg P/ha in order to improve the production of dry bean. / NRF (National Research Foundation)

The use of pasture to provide low cost feed for dairy and other farm animals is an important factor in the success of livestock operations. Some of the factors which influence the income from pasture land are: management, pasture mix, and climate. The management of a pasture can determine to a great extent the value of pasture in a farming enterprise. Irrigating the pasture at the right time, using the right fertilizer, and proper methods of harvesting are examples of some of the management problems facing the grassland farmer.

In Limpopo Province of South Africa, poor soil fertility and low crop yields are serious problems facing resource poor smallholder farmers. A survey of over 60 farmers in 2 villages (Gabaza and GaKgoroshi) found that most of the smallholder farmers were women (68%), elderly (50% above 68 years of age) and had not attended school or only attended up to the primary level (80%). Very few farmers kept livestock (usually in small numbers) and most grew cereal and legume crops (on 1ha of land) for home consumption and livestock feed, with legumes being planted on 13% of the land. The study showed that 80% of farmers were not fully aware of the benefits of legumes in fixing nitrogen (N) and improving yield. A field study at the survey village of Gabaza found that the application of fertiliser N and grass mulch combination and fertiliser N plus guarbean mulch significantly increased plant height and maize shoot growth at 4 and 8 weeks after planting. However, when grass mulch was without N fertiliser, there was no increase in maize growth relative to the control (0N). A farming systems simulation model (Agricultural Production Systems sIMulator - APSIM) was used to simulate this field study as well as over the long-term (1971 to 2008). Simulation analysis showed poor average maize yield (<3000 kg ha⁻ ¹) with the application of grass residues even when used with 30 kg N fertiliser. However, the application of guarbean residues as mulch with or without N fertiliser and as green manure increased maize yields to >4000 kg ha⁻ ¹. Simulation showed that the grass mulch with or without the addition of N fertiliser reduced water stress and soil water evaporation but increased N stress during the reproductive phase of the crop in most seasons. When guarbean mulch was used as green manure by itself, or mulch plus N fertiliser, N stress was reduced but water stress and soil water evaporation were increased which could have been due to faster decomposition of legume mulch as compared to grass mulch. Addition of N fertiliser reduced N stress to maize but increased water stress and soil water evaporation similar to the guarbean mulch because of high soil evaporation. APSIM analysis clearly showed the importance of N x soil water interactions in determining maize growth and yield at Gabaza. Therefore, two studies were undertaken in the laboratory in Australia to determine the dynamics of carbon (C) and N where residues of different qualities [canola (C:N 43), wheat (26), pea (9) and mucuna (14)] were applied to clay loam (Tarlee) or sandy (Waikerie) soils. In experiment 1, where residues were incorporated into the two soils, the cumulative CO₂-C evolution for the wheat and canola treatments at the end of the incubation period were fairly similar but significantly higher than for pea, mucuna and the control. In general, the application of residues increased microbial biomass C more than the control, with highest increases up to 1.48 and 1.56 mg C g⁻ ¹ soil for canola and wheat in Tarlee soil, respectively and 0.82 mg C g⁻ ¹ soil for pea in Waikerie soil. Even though the Tarlee soil showed greater C release than Waikerie soil, the C turnover from the residues between the 2 soils was not significantly different except for pea residues. Canola and wheat residues were found to immobilise N whereas N content increased in both soils with the application of legumes (pea and mucuna). In experiment 2, mucuna, pea and wheat residues were either incorporated or applied as surface mulches on Waikerie soil. Initially the CO₂-C release was higher for incorporated than mulched residues and CO₂-C released was higher for pea residues. However, at the end of the incubation more CO₂-C was released with the application of wheat residue indicating differences between residue types in the pattern of soil respiration. Microbial biomass C was higher for incorporated than mulched residue treatments; pea residue showed the highest biomass C for incorporated (0.78 mg C g⁻ ¹ soil) whereas mucuna had the highest microbial biomass (0.11 mg C g⁻ ¹ soil) treatments. The method of residue application resulted in a significant difference in C turnover between residues, with pea residue showing significant increase in C utilisation than mucuna and wheat. The pea residues, which had the lowest C:N, increased soil mineral N more than other treatments in both incorporated and mulched treatments. Lower mineralisation of N observed in residues of high C:N ratio compared to the control could be due to immobilisation of N. Therefore, understanding the nutrient dynamics of different crop residues could play an important role in the management of residues in different soil types. Based on these results it can be concluded that legume residues have the potential to improve soil fertility and crop yields in dryland farmers’ fields in Limpopo. Extension programs aimed at increasing farmers’ knowledge of the benefits of N fixation by legumes may increase their adoption and thereby improve soil fertility and maize yield. / Thesis (M.Ag.Sc.) -- University of Adelaide, School of Agriculture, Food and Wine, 2010

Switchgrass, Panicum virgatum, is being developed as an economically and ecologically sustainable biomass crop. Nitrogen is considered one of the most limiting inputs of switchgrass. Alternatives to synthetic nitrogen fertilization may be nitrogen-fixing legumes interseeded into switchgrass. The objectives of this research were: (1) develop efficient legume management strategies for switchgrass production systems, (2) evaluate and identify cool and warm-season legumes that can be grown compatibly with switchgrass, (3) determine whether switchgrass yields are increased by legume N-fixation, and (4) determine N-fixation of common (Vicia sativa) and hairy vetch (Vicia villosa). This study examined the establishment and persistence of ten different legume species in ‘Alamo’, a lowland variety of switchgrass in two switchgrass production systems: a one-cut biomass harvest and a two-cut forage/biomass harvest. Cool-season legumes were alfalfa (Medicago sativa), arrowleaf clover (Trifolium vesiculosum), common vetch, crown vetch (Securigera varia), red clover (Trifolium pretense), hairy vetch, and crimson clover (Trifolium incarnatum). Warm-season legumes were Illinois bundle flower (Desmanthus illinoensis), trailing wild bean (Strophostyles helvula), and partridge pea (Chamaechrista fasciculata). Red clover showed the highest plant densities and increase in switchgrass yields when interseeded into existing switchgrass stands in both harvest systems. Crude protein levels were highest in the 135 kg N ha-1 treatment in the forage cut of the two-cut harvest system. Arrowleaf clover, crimson clover, and red clover had high stand densities with annual reseeding. A combination of cool-season legumes, crimson clover and common vetch, in combination with warm-season partridge pea, were established in existing switchgrass stands after one year. Common vetch was evaluated for its nitrogen fixing capacity, seed germination, establishment, and effects on yield of switchgrass. Scarification by sulfuric acid had higher seed germination than other scarification treatments, except 100 grit sandpaper treatment for one minute at 0.7 kg of pressure. Common and hairy vetch nitrogen contributions were 59.3 and 43.3 kg N ha-1 respectively at seeding rates of 6.7 kg PLS ha-1. Switchgrass yields can increase with common and hairy vetch seeding rates of 7.6 and 10.4 kg PLS ha-1 to achieve 67 kg N ha-1, the recommended rate of N-fertilization for switchgrass stands.

While the extent of grasslands in Southern Ontario has been greatly reduced, urban and suburban areas provide numerous potential sites for their restoration. Grassland restoration in cities can provide ecological and cultural benefits, but soil conditions may be less than optimal for native species recovery. This thesis explores the use of soil amendments in order to address nutrient deficiency on old-field meadow restoration sites. Five treatments were tested, namely the addition of (1) nitrogenous fertilizer, (2) native legume species, (3) biochar, (4) a combination of the previous three, and (5) an unaltered control. Each treatment was replicated four times on two different test plots in Waterloo Region, Ontario, Canada (Huron Natural Area and Springbank Farm), for a total of 40 subplots. The experimental plots were tilled in the fall of 2011, a randomly selected treatment was applied to each subplot, and then all were seeded with a mix of five native meadow species (2 grass, 2 forb, 1 sedge). Soil samples were taken from each subplot both before treatment application and also at the end of the growing season in 2012, and tested for nutrient levels (N, P, K), pH and organic matter. Species richness, as well as soil temperature and moisture, were regularly monitored over the growing season. In the fall of 2012, above-ground vegetation was harvested to assess accrued biomass. In order to detect differences in means, results were tested using one-way and repeated-measures ANOVAs, where appropriate. Pearson???s product-moment correlations were also employed to test for linear dependence between variables. There were no significant differences between treatments in terms of soil nutrients or pH at either site. At Huron Natural Area, post-treatment biochar-treated subplots had slightly higher levels of organic matter than controls (p=0.095). Values for species richness, above-ground biomass, soil temperature and soil moisture did not vary significantly between treatments. Species richness at Huron Natural Area was positively correlated with 2011 N (r=0.42; p=0.07) and organic matter (r=0.52; p=0.02) levels, while at Springbank Farm it was negatively correlated with 2012 N levels (r=-0.67; p<0.001). Above-ground biomass at Huron Natural Area was positively correlated with 2011 and 2012 P levels (both r=0.52; p=0.02), while at Springbank Farm it was positively correlated with 2011 N, P, K and organic matter, and 2012 N, P and K (all r>0.44; p<0.05). At Huron Natural Area, above-ground biomass was negatively correlated with soil temperature (r=-0.64; p<0.0001) and positively correlated with soil moisture (r=0.38; p=0.1). This study uncovered a strong, but variable, relationship between N concentration and species richness in old-field meadows. Furthermore, productivity was tightly correlated with different soil nutrient concentrations at each study site. The results demonstrate the need for restoration approaches to address local soil conditions on order to be effective. To date, there have been very few studies on meadow restoration, particularly in North America. More, and longer-term, multivariate studies are needed in order to test the effectiveness of different techniques.

Overall soil productivity is declining in the U.S. due to loss of soil organic matter (SOM). Decreased SOM lowers soil water storage, reduces water infiltration, slows aggregate formation, and depletes soil of nutrients. In many systems, crop nutrients are replaced by expensive synthetic fertilizers that can lead to environmental concerns. This practice is not economically or environmentally sustainable in the long term. To secure future soil use and crop production, sustainable management practices are needed to prevent further SOM depletion. Incorporating legumes into cropping systems is one alternative that can bolster soil organic C (SOC) (key indicator of SOM) and reduce N fertilizer applications through symbiotic legume N fixation. Three studies were conducted over multiple years at the Texas A&M AgriLife Research and Extension Center near Overton, TX. Annual cool- and warm-season legumes were evaluated as potential green manure crops and intercrops under grain sorghum [Sorghum bicolor (L.) Moench], high-biomass sorghum [Sorghum bicolor (L.) Moench], and annual forage cropping systems. These studies quantified legume soil moisture usage and C and N contributions to the soil and subsequent crop yields in East Texas. Primary project objectives were to maintain or maximize primary crop yields at reduced N fertilizer rates and to build SOC through the integration of legume green manures and intercrops. Green manuring cool-season legumes showed the most beneficial effect on SOC, soil total N, and crop yields; however, significant increases in yield were only detected after three years in rotation. Intercropping Iron-and-Clay cowpea (Vigna unguiculata L. [Walp]) decreased yield of both high-biomass sorghum and grain sorghum due to competitive vegetative growth. Iron-and-Clay did however improve biomass yields of high-biomass sorghum in two subsequent years when implemented as a green manure. Despite large N yields as high as 310 kg ha-1, impacts of legumes on annual forage crops was limited. Poor response was likely a result of previous field history in which a permanent warm-season grass pasture was cultivated for site preparation and mineralized SOC released substantial amounts of available N. Under low soil N conditions, legume green manures produce enough N to likely reduce N fertilizer requirements cost-effectively for subsequent crops in East Texas.

In Limpopo Province of South Africa, poor soil fertility and low crop yields are serious problems facing resource poor smallholder farmers. A survey of over 60 farmers in 2 villages (Gabaza and GaKgoroshi) found that most of the smallholder farmers were women (68%), elderly (50% above 68 years of age) and had not attended school or only attended up to the primary level (80%). Very few farmers kept livestock (usually in small numbers) and most grew cereal and legume crops (on 1ha of land) for home consumption and livestock feed, with legumes being planted on 13% of the land. The study showed that 80% of farmers were not fully aware of the benefits of legumes in fixing nitrogen (N) and improving yield. A field study at the survey village of Gabaza found that the application of fertiliser N and grass mulch combination and fertiliser N plus guarbean mulch significantly increased plant height and maize shoot growth at 4 and 8 weeks after planting. However, when grass mulch was without N fertiliser, there was no increase in maize growth relative to the control (0N). A farming systems simulation model (Agricultural Production Systems sIMulator - APSIM) was used to simulate this field study as well as over the long-term (1971 to 2008). Simulation analysis showed poor average maize yield (<3000 kg ha⁻ ¹) with the application of grass residues even when used with 30 kg N fertiliser. However, the application of guarbean residues as mulch with or without N fertiliser and as green manure increased maize yields to >4000 kg ha⁻ ¹. Simulation showed that the grass mulch with or without the addition of N fertiliser reduced water stress and soil water evaporation but increased N stress during the reproductive phase of the crop in most seasons. When guarbean mulch was used as green manure by itself, or mulch plus N fertiliser, N stress was reduced but water stress and soil water evaporation were increased which could have been due to faster decomposition of legume mulch as compared to grass mulch. Addition of N fertiliser reduced N stress to maize but increased water stress and soil water evaporation similar to the guarbean mulch because of high soil evaporation. APSIM analysis clearly showed the importance of N x soil water interactions in determining maize growth and yield at Gabaza. Therefore, two studies were undertaken in the laboratory in Australia to determine the dynamics of carbon (C) and N where residues of different qualities [canola (C:N 43), wheat (26), pea (9) and mucuna (14)] were applied to clay loam (Tarlee) or sandy (Waikerie) soils. In experiment 1, where residues were incorporated into the two soils, the cumulative CO₂-C evolution for the wheat and canola treatments at the end of the incubation period were fairly similar but significantly higher than for pea, mucuna and the control. In general, the application of residues increased microbial biomass C more than the control, with highest increases up to 1.48 and 1.56 mg C g⁻ ¹ soil for canola and wheat in Tarlee soil, respectively and 0.82 mg C g⁻ ¹ soil for pea in Waikerie soil. Even though the Tarlee soil showed greater C release than Waikerie soil, the C turnover from the residues between the 2 soils was not significantly different except for pea residues. Canola and wheat residues were found to immobilise N whereas N content increased in both soils with the application of legumes (pea and mucuna). In experiment 2, mucuna, pea and wheat residues were either incorporated or applied as surface mulches on Waikerie soil. Initially the CO₂-C release was higher for incorporated than mulched residues and CO₂-C released was higher for pea residues. However, at the end of the incubation more CO₂-C was released with the application of wheat residue indicating differences between residue types in the pattern of soil respiration. Microbial biomass C was higher for incorporated than mulched residue treatments; pea residue showed the highest biomass C for incorporated (0.78 mg C g⁻ ¹ soil) whereas mucuna had the highest microbial biomass (0.11 mg C g⁻ ¹ soil) treatments. The method of residue application resulted in a significant difference in C turnover between residues, with pea residue showing significant increase in C utilisation than mucuna and wheat. The pea residues, which had the lowest C:N, increased soil mineral N more than other treatments in both incorporated and mulched treatments. Lower mineralisation of N observed in residues of high C:N ratio compared to the control could be due to immobilisation of N. Therefore, understanding the nutrient dynamics of different crop residues could play an important role in the management of residues in different soil types. Based on these results it can be concluded that legume residues have the potential to improve soil fertility and crop yields in dryland farmers’ fields in Limpopo. Extension programs aimed at increasing farmers’ knowledge of the benefits of N fixation by legumes may increase their adoption and thereby improve soil fertility and maize yield. / Thesis (M.Ag.Sc.) -- University of Adelaide, School of Agriculture, Food and Wine, 2010

The conversion of atmospheric dinitrogen (N2) into plant available nitrogen (N), by legumes and their prokaryotic microsymbionts, is an integral component of sustainable farming. A key constraint to increasing the amount of N2 fixed in agricultural systems is the prevalence of symbioses which fix little or no N. The biotic factors leading to this suboptimal N2 fixation have not been extensively analysed. Using the widely studied and cultivated perennial legume Medicago sativa and the model indeterminate annual legume Medicago truncatula with the sequenced bacterial microsymbiont Sinorhizobium meliloti 1021 (Sm1021) as a basis, the work presented in this thesis examined the effectiveness of N2 fixation in these associations and in other comparable systems and investigated factors which lead to the establishment of suboptimally effective symbioses. The ability of Sm1021, S. medicae WSM419 and the uncharacterised Sinorhizobium sp. WSM1022 to fix N with M. truncatula A17, M. sativa cv. Sceptre and a range of other Medicago spp. was evaluated in N-limited conditions. As measured by plant shoot dry weights and N-content, Sm1021 was partially effective with M. truncatula A17 whereas WSM1022 and WSM419 were both effective with this host in comparison to nitrogen-fed (N-fed) control plants. In contrast, Sm1021 and WSM1022 were effective with M. sativa while WSM419 was only partially effective. Nodules induced by Sm1021 on M. truncatula A17 were more numerous, paler, smaller in size and more widely distributed over the entire root system than in the two effective symbioses with this host. On the contrary, nodule number, size and distribution did not differ between these three strains on M. sativa. WSM1022 was effective on M. littoralis, M. tornata and two other cultivars of M. truncatula (Jemalong and Caliph) but Sm1021 was only partially effective on these hosts. These data indicate that the model indeterminate legume symbiosis between M. truncatula and Sm1021 is not optimally matched for N2 fixation and that Sm1021 possesses broader symbiotic deficiencies. In addition, the interaction of WSM1022 with M. polymorpha (small white nodules but does not fix N), M. murex (does not nodulate), M. arabica (partially effective N2 fixation) and M. sphaeorcarpus (partially effective N2 fixation), and the sequence of the 16S rDNA, are all consistent with this isolate belonging to the species S. meliloti. The colony morphology of TY, half-LA and YMA agar plate cultures of Sm1021, WSM419 and WSM1022 suggested differences in EPS profiles between these strains. Sm1021 is very dry, compared to the mucoid WSM419 and extremely mucoid WSM1022. Sm1021 is known to carry an insertion in expR rendering the gene non-functional and resulting in the dry colony phenotype. WSM419 has an intact copy of expR, while the expR status of WSM1022 is not known. Rm8530, a spontaneous mucoid derivative of Sm1021 with an intact expR, was significantly less effective with M. truncatula than Sm1021, but there was no difference in effectiveness between these strains on M. sativa. The effectiveness of Sm1021, when complemented with a plasmid-borne copy of expR from Rm8530, was significantly reduced on M. truncatula but not M. sativa, implicating a functional expR as being the cause of reduced N2 fixation observed with Rm8530 on M. truncatula. ExpR could reduce the effectiveness of Rm8530 by acting as a negative regulator of genes essential for symbiosis with M. truncatula, or by altering the quantity or structure of succinoglycan and/or galactoglucan produced. These data support the emerging view of ExpR being a central regulator of numerous cellular processes. The timing of nodulation between Sm1021 and WSM419 on M. truncatula and M. sativa was investigated. Compared to the other symbioses analysed, the appearance of nodule initials and nodules was delayed when M. truncatula was inoculated with Sm1021 by 3 and 4 days, respectively. To explore whether events during early symbiotic signalling exchange could account for these observed delays, leading to the establishment of a suboptimal N2-fixing symbiosis, a novel system was developed to compare the response of the Sm1021 transcriptome to roots and root exudates of M. truncatula A17 and M. sativa cv. Sceptre. This system consisted of a sealed 1 L polycarbonate chamber containing a stainless steel tripod with a wire mesh platform on which surface-sterilised seeds could be placed and allowed to germinate through the mesh, into a hydroponic medium below. After germination, Sm1021 cells were inoculated into the hydroponic solution, exposed to the roots and root exudates for 16 h, harvested and their RNA extracted. Comparison of Sm1021 mRNA from systems exposed to M. truncatula or M. sativa revealed marked differences in gene expression between the two. Compared to the no plant control, when M. sativa was the host plant, 23 up-regulated and 40 down-regulated Sm1021 genes were detected, while 28 up-regulated and 45 down-regulated genes were detected with M. truncatula as the host. Of these, 12 were up-regulated and 28 were down-regulated independent of whether M. truncatula or M. sativa was the host. Genes expressed differently when exposed to either M. truncatula or M. sativa included nex18, exoK, rpoE1 and a number of other genes coding for either hypothetical proteins or proteins with putative functions including electron transporters and ABC transporters. Characterisation of these differentially expressed genes along with a better understanding of the composition of M. truncatula root exudates would yield a clearer insight into the contribution of early signal exchange to N2 fixation. Comparison of the regulation of nodule number between Sm1021 and WSM419 on M. truncatula and M. sativa revealed nodule initials at 42 days post-inoculation (dpi) on M. truncatula inoculated with Sm1021. In contrast, no new nodule initials were present 21 dpi on any of the other interactions examined. Moreover, analysis of nodule sections revealed that the number of infected cells in M. truncatula-Sm1021 nodules was less than for comparable symbioses. These data suggest that nodule number is not tightly controlled in the M. truncatula-Sm1021 association, probably due to N2 fixation being insufficient to trigger the down regulation of nodulation. Quantification of N2 fixation activity in this and other more effective symbioses is required. The poor effectiveness of the M. truncatula-Sm1021 symbiosis makes these organisms unsuitable as the model indeterminate interaction and the implications for legume research are discussed. The recently sequenced WSM419 strain, revealed here to fix N2 more effectively with M. truncatula than Sm1021, may be a better model microsymbiont, although WSM419 is only partially effective for N2 fixation with M. sativa. The sequencing of S. meliloti WSM1022, a highly effective strain with both M. truncatula and M. sativa, would provide a valuable resource in indentifying factors which preclude the establishment of effective symbioses.

The major antinutritive factor in Leucaena for ruminants is condensed tannin (CT). CT bind proteins, incurring a negative effect on protein utilisation. The two major factors affecting the ability of CT to bind protein have been purported to be CT size and the pH of the reaction environment. To test these hypotheses the protein precipitating capacities of CT extracted from four promising Leucaena genotypes, L. leucocephala (K636), L. pallida (CQ3439), L. trichandra (CPI46568), and L. collinsii (OFI52/88) were assessed. L. leucocephala had approximately half the ability to precipitate protein on a g/g basis than L. pallida or L. trichandra while L. collinsii gave no measurable ability to precipitate protein (reaction environment=pH 5.0). Increasing or decreasing the pH of the reaction solution away from pH 5.0 (the isoelectric point of the protein) reduced the ability of CT from all the species to precipitate protein; the decrease being higher a pH 2.5 than at pH 7.5. At pH 2.5 L. leucocephala CT completely lost its capacity to precipitate protein. The relatively poor ability of L. leucocephala CT to bind protein at pH’s approximating those at the abomasum suggests L. leucocephala may have the greatest potential of the four Leucaena’s tested for increasing the extent of feed protein escaping ruminant degradation for later release and digestion in the small intestine, hence increasing the total amount of protein absorbed by ruminants. CT fractions from each Leucaena were also separated into individual CT’s, by size-exclusion chromatography and examined for protein precipitating capacity. In general it was found that the larger sized CT of the accessions L. pallida and L. trichandra could precipitate more protein than the smaller sized CT. This pattern was not found for L. leucocephala.

Made available in DSpace on 2014-06-11T19:32:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-05-05Bitstream added on 2014-06-13T21:05:26Z : No. of bitstreams: 1 netto_dp_dr_botfmvz.pdf: 505159 bytes, checksum: fdbb2ee95004f51e21168fda4ef26f4b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / Objetivou-se avaliar como a substituição parcial de silagem de milho por pastagem de alfafa afeta o desempenho de vacas leiteiras e a viabilidade econômica do sistema. Usaramse 24 vacas da raça Holandesa, em estádio médio de lactação, num delineamento em blocos ao acaso. O período experimental durou 84 dias. Os tratamentos foram: dieta à base de silagem de milho em confinamento; ou silagem de milho substituída parcialmente por pastejo restrito (limitado a quatro horas/dia) ou irrestrito de alfafa. O pastejo foi rotacionado, e a quantidade de concentrado igual (4,5 kg de MS/vaca/dia) em todos os tratamentos. A massa de forragem foi 2338,0 e 1878,0 kg de MS/ha e a oferta, 1,8 e 4,2 kg MS/100 kg PV, nos tratamentos pastejo restrito e irrestrito, respectivamente. A produção de leite não diferiu entre tratamentos, cujas médias foram 25,9±1; 25,8±1 e 25,2±1 litros/vaca/dia no confinamento, pastejo restrito e pastejo irrestrito, respectivamente. A produção de leite por área foi 59 litros/ha/dia no pastejo restrito e 63 litros/ha/dia no pastejo irrestrito, enquanto no confinamento foi 48 litros/ha/dia. A substituição parcial de silagem de milho por alfafa em pastejo não limitou o desempenho produtivo dos animais e mostrou-se economicamente vantajosa em relação ao confinamento. / The objective was to evaluate how the partial replacement of corn silage with alfafa grazing affects dairy cow performance and profitability. Twenty four Holstein dairy cows in mid-lactation were used in a randomized block design. The experimental period lasted 84 days. The treatments were: a corn silage-based diet fed on drylot; or partial replacement of corn silage with either restricted alfalfa grazing (limited to 4 hours/day) or unrestricted grazing. A rotational grazing system was used and the amount of concentrate fed was the same (4.5 kg of DM/cow/day) for all treatments. Forage availability was 2,338.0 and 1,878.0 kg DM/ha and forage-on-offer was 1.8 and 4.2 kg DM/100 kg LW under restricted or unrestricted grazing, respectively. No difference in milk production/cow/day was observed among treatments. Mean milk production was 25.9±1, 25.8±1 and 25.2±1 liters/cow/day for feedlot, restricted grazing or unrestricted grazing, respectively. Milk production per hectare was 59 liters/day under restricted grazing and 63 liters/day under unrestricted grazing, whereas it was 48 liters/day on drylot. The partial replacement of corn silage by alfalfa grazing did not limit animal performance and was shown to be economically advantageous as compared to drylot feeding.