Nitrogen and carbohydrate fractions on Tifton-85 pastures overseeded with annual winter and summer forage species in different seasons

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nitrogen and carbohydrate fractions in exclusive Tifton 85 and in pasture oversown with annual winter forage species

O experimento foi conduzido na FCAV - Campus de Jaboticabal, no período de inverno-primavera-verão de 2001-2002, com o objetivo de determinar o fracionamento de compostos nitrogenados e de carboidratos do Tifton 85 (Cynodon nlemfuensis Vanderyst x Cynodon dactylon (L.) Pers), exclusivo ou sobressemeado com forrageiras anuais de inverno. Os tratamentos testados foram: aveia preta (Avena strigosa Schreb); aveia amarela (Avena byzantina C. Koch); triticale (X Triticosecale Wittmack); aveia preta + aveia amarela; aveia preta + triticale; aveia amarela + triticale; aveia preta + aveia amarela + triticale, sobressemeados sobre Tifton 85 e, sem consorciação (testemunha). O delineamento experimental utilizado foi o de blocos completos ao acaso, com três repetições. O corte das forrageiras foi realizado a 20 cm de altura (presença de forrageiras de inverno) e 10 cm de altura (ausência das forrageiras de inverno). Foram determinados os teores de proteína bruta, carboidratos totais, e o fracionamento dos compostos nitrogenados e de carboidratos. Houve redução nos teores dos compostos químicos das espécies de forrageiras de inverno e no Tifton 85 ao longo dos períodos de avaliações. Os conteúdos de compostos nitrogenados e de carboidratos apresentaram grande variação durante os períodos avaliados, relacionando com as características morfológicas das espécies de gramineas e com a composição botânica das pastagens.

Avaliação de forrageiras de inverno irrigadas sob pastejo

O experimento foi conduzido na UNESP - Jaboticabal com o objetivo de obter informações sobre o rendimento de matéria seca (RMS) e composição química das forrageiras de inverno, aveia preta (Avena strigosa Schreb) e triticale (X Triticosecale Wittmack), em plantio direto sob palhada de área com milheto (Pennisetum americanum (L.) K. Schum.) ou híbrido sorgo sudão (Sorghum bicolor (L.) Moench x Sorghum sudanense (Piper) Stapf) submetidas a pastejo. A forragem foi rebaixada por vacas da raça Holandês. O delineamento experimental utilizado foi em blocos casualizados, em arranjo de parcelas subdivididas, sendo analisado nas parcelas as espécies forrageiras e nas sub-parcelas as épocas de pastejo, com quatro repetições. Os tratamentos testados foram: AS: Aveia Preta sobre palhada de sorgo; AM: Aveia preta sobre palhada de milheto; TS: Triticale sobre palhada de sorgo; e, TM: Triticale sobre palhada de milheto. As pastagens apresentaram RMS semelhantes e, em relação às épocas de avaliação observou-se menor rendimento no segundo corte. Foram observados maiores teores de PB e de FDA na forragem colhida no primeiro corte e de hemicelulose no segundo corte, enquanto os valores de FDN não foram diferentes. A forragem de triticale apresentou menor conteúdo de PB e maiores teores de constituintes da parede celular.

Delivering superior forage oat varieties for sub-tropical Australia

This full application seeks ongoing funding for the Agri-Science Queensland's forage oat breeding program through the Meat and Livestock Australia Partners in Innovation program with Heritage Seeds as the Donor Company and the commercial collaborator. The focus of the breeding program will shift to the use of minor genes that confer partial resistance or adult plant resistance to leaf rust. Accumulation of several minor genes in a single variety should produce a high level of effective field resistance, and better durability of resistance, with less likelihood of a mutational change in the pathogen.

Northern challanges for profitable production of quality naked oat

Naked oat (Avena sativa f.sp. nuda L.) is the highest quality cereal in northern growing conditions. However the cultivation area of naked oat is remarkably small. Major challenges for naked oat production are to observe its nakedness. The caryopsis of naked oat is sensitive to mechanical damage at harvest, especially at high grain moisture content. The greater the grain moisture content of naked oat at harvest, the more loses of germination capacity was caused by threshing. For producing high quality naked oat seed, it is recommended that harvesting be done at as low grain moisture content as possible. However, if this is not possible, better germination can be ensure with gentle harvest by reducing the cylinder speed. In spite of conventional oat s excellent fat and amino acid composition in animal feed use, as far as nutritional value is concerned, the total energy yield of oat is weaker than other cereals because of the hulls. Also with naked oat the dehulling is not complete, while hull content on different cultivars mostly varied between one to six percent. In addition to genotype, environmental conditions markedly control the expression of nakedness. Thresher settings had only limited effects on hull content. The function of hulls is to protect the groat, but this was confirmed only for Finnish, small grain, cultivar Lisbeth. The oat kernel is generally covered with fine silky hairs termed trichomes. The trichomes of naked oat are partly lost during threshing and handling of grains. Trichomes can cause itchiness in those handling the grains and also accumulate and form fine dust and can block-up machinery. The cultivars differed considerably in pubescence. Some thresher settings, including increased cylinder speed, slightly increased grain polishing such that grains had some areas completely free of trichomes. Adjusting thresher settings was generally not an efficient means of solving the problems associated with naked oat trichomes. The main differences in cultivation costs between naked and conventional oat lie in the amount of seeds required and the drying costs. The main differences affecting the economic result lie in market prices, yield level and feed value. The results indicate that naked oat is financially more profitable than conventional oat, when the crop is sold at a specific price at all yield levels and when the crop is used as feed at highest yield level. At lower yield levels, conventional oat is, in spite of its lower feed value, the more profitable option for feed use. Dehulled oat did not achieve the same economic result as naked oat, as the cost of dehulling, including the hull waste, was considerable. According to this study naked oat can be cultivated successfully under northern conditions, when taking into consideration the soft, naked grain through cultivation chain.

Role of heat treatment in the processing and quality of oat flakes

This thesis reports on investigations into the influence of heat treatment on the manufacturing of oat flakes. Sources of variation in the oat flake quality are reviewed, including the whole chain from the farm to the consumer. The most important quality parameters of oat flakes are the absence of lipid hydrolysing enzymes, specific weight, thickness, breakage (fines), water absorption. Flavour, colour and pasting properties are also important, but were not included in the experimental part of this study. Of particular interest was the role of heat processing. The first possible heat treatment may occur already during grain drying, which in Finland generally happens at the farm. At the mill, oats are often kilned to stabilise the product by inactivating lipid hydrolysing enzymes. Almost invariably steaming is used during flaking, to soften the groats and reduce flake breakage. This thesis presents the use of a material science approach to investigating a complex system, typical of food processes. A combination of fundamental and empirical rheological measurements was used together with a laboratory scale process to simulate industrial processing. The results were verified by means of industrial trials. Industrially produced flakes at three thickness levels (nominally 0.75, 0.85 and 0.90 mm) were produced from kilned and unkilned oat groats, and the flake strength was measured at different moisture contents. Kilning was not found to significantly affect the force required to puncture a flake with a 2mm cylindrical probe, which was taken as a measure of flake strength. To further investigate how heat processing contributes to flake quality, dynamic mechanical analysis was used to characterise the effect of heat on the mechanical properties of oats. A marked stiffening of the groat, of up to about 50% increase in storage modulus, was observed during first heating at around 36 to 57°C. This was also observed in tablets prepared from ground groats and extracted oat starch. This stiffening was thus attributed to increased adhesion between starch granules. Groats were steamed in a laboratory steamer and were tempered in an oven at 80 110°C for 30 90 min. The maximum force required to compress the steamed groats to 50% strain increased from 50.7 N to 57.5 N as the tempering temperature was increased from 80 to 110°C. Tempering conditions also affected water absorption. A significantly higher moisture content was observed for kilned (18.9%) compared to unkilned (17.1%) groats, but otherwise had no effect on groat height, maximum force or final force after a 5 s relaxation time. Flakes were produced from the tempered groats using a laboratory flaking machine, using a roll gap of 0.4 mm. Apart from specific weight, flake properties were not influenced by kilning. Tempering conditions however had significant effects on the specific weight, thickness and water absorption of the flakes, as well as on the amount of fine material (<2 mm) produced during flaking. Flake strength correlated significantly with groat strength and flake thickness. Trial flaking at a commercial mill confirmed that groat temperature after tempering influenced water absorption. Variation in flake strength was observed , but at the groat temperatures required to inactivate lipase, it was rather small. Cold flaking of groats resulted in soft, floury flakes. The results presented in this thesis suggest that heating increased the adhesion between starch granules. This resulted in an increase in the stiffness and brittleness of the groat. Brittle fracture, rather than plastic flow, during flaking could result in flaws and cracks in the flake. These would be expected to increase water absorption. This was indeed observed as tempering temperature increased. Industrial trials, conducted with different groat temperatures, confirmed the main findings of the laboratory experiments. The approach used in the present study allowed the systematic study of the effect of interacting process parameters on product quality. There have been few scientific studies of oat processing, and these results can be used to understand the complex effects of process variables on flake quality. They also offer an insight into what happens as the oat groat is deformed into a flake.

Digestibility, nutrient balance and urinary purine derivative excretion in dry yak cows fed oat hay at different levels of intake

A feeding trial A as conducted at the farm of Qinghai Academy of Animal and Veterinary Science, Xining, China during 1996 - 1997 with three dry yak cows (initial body weight 163 - 197 kg, age 5 - 6 years) by using 3 x 3 Latin Square Design to determine the effect of levels of feed intake on digestion, nitrogen balance and purine derivative excretion in urine of yak cows. The animals were fed oat hay (nitrogen 13.5 g/kg dry matter (DM), metabolisable energy 8.3 MJ/kg DM), i.e., 0.3, 0.6 and 0.9 of voluntary intake (VI). Each intake treatment lasted for 17 days and the samples (feeds, faeces and urine) were collected during last 7 days of each period. The results indicate that digestibility of dietary DM, OM, NDF and ash declined when intake levels increased from 0.3 to 0.9 VI [DM, from 66.1% to 59.1% (P < 0.05); OM, from 68.1% to 59.9% (P < 0.05); NDF, from 62.1% to 54.3% (P < 0.05); and ash, from 33.9% to 11.8% (P < 0.05)]. Around 0.10 g N/kg W-0.75 was deficient daily in yak cows at 0.3 VI, and positive N balances were observed at 0.6 and 0.9 VI. Intake levels significantly (P < 0.05) affected total PD excretion in yak urine. The proportion of allantoin increased (P < 0.05) and uric acid decreased (P < 0.05) as intake level of feed increased. (C) 2004 Elsevier B.V. All rights reserved.

The regulation of oat coleoptile phosphoenolpyruvate carboxylase and malic enzyme by Hâ ½ and metabolites : kinetic evidence for and against a cytosolic pH-stat

Phosphoenolpyruvate carboxylase (PEPC) and malic enzyme activities in soluble protein extracts of Avena coleoptiles were investigated to determine whether their kinetics were consistent with a role in cytosol pH regulation. Malic enzyme activity was specific for NADP+ and Mn2+. Maximal labelled product formation from [14C]-substrates required the presence of all coenzymes, cofactors and substrates. Plots of rate versus malate concentration, and linear transformations there- 2 of, indicated typical Michaelis-Menten kinetics at non-saturating malate levels and substrate inhibition at higher malate levels. pH increases between 6.5 and 7.25 increased near-optimal activity, decreased the degree of substrate inhibition and the Kmapp(Mn2+) but did not affect the Vmax or Kmapp(malate). Transformed data of PEPC activity demonstrated non-linear plots indicative of non-Michaelian kinetics. pH increases between 7.0 and 7.6 increased the Vmax and decreased the Km app (Mg2+) but did not affect the Kmapp(PEP). Various carboxylic acids and phosphorylated sugars inhibited PEPC and malic enzyme activities, and these effects decreased with pH increases. Metabolite inhibited malic enzyme activity was non-competitive and resulted mainly from Mn2+ chelation. In contrast, metabolite inhibited PEPC activity was unique for each compound tested, being variously dependent on the PEP concentration and the pH employed. These results indicate that fluctuations in pH and metabolite levels affect PEPC and malic enzyme activities similarly and that 3 the in vitro properties of PEPC are consistent with its proposed role in a pH-stat, whereas the in vitro properties of the malic enzyme cannot be interpreted in terms of a role in pH regulation.

Effects of host plant drought stress on the performance of the bird cherry-oat aphid, Rhopalosiphum padi (L.): a mechanistic analysis

1. The growth (increase in height and leaf number) of four grass species was reduced by a -0.5 MPa drought stress, but the performance of an associated herbivore, Rhopalosiphum padi (L.), was not affected consistently. The intrinsic rate of increase of R. padi was reduced by drought stress on three grass species, including Dactylis glomerata (L.), but was unaffected on Arrhenatherum elatius (L.). Therefore, there is no general relationship in the effect of plant drought on an insect herbivore, even among closely related host plant species. 2. Drought stress increased the quality of plant phloem sap, as indicated by increased sieve element osmotic pressure and essential amino acid concentrations. Thus, diet quality could not account for the reduced performance of R. padi under drought stress. The concentration of essential amino acids in the phloem of well-watered A. elatius was, however, lower than that of well-watered D. glomerata, correlating with the decreased performance of aphids on well-watered A. elatius. 3. There were no differences in aphid feeding duration between watering treatments or plant species but sap ingestion rates were reduced significantly under drought stress. 4. Using the measure of dietary amino acid concentrations and the estimate of sap ingestion, the essential amino acid flux through aphids was calculated. Compared with the flux through aphids feeding on well-watered D. glomerata, there was a reduction in aphids feeding on drought-stressed D. glomerata and drought-stressed A. elatius due to lower sap ingestion rates. The flux through aphids on well-watered A. elatius was also reduced due to low phloem essential amino acid concentrations. Thus, the performance of an aphid is correlated with the availability and accessibility of essential amino acids.

In vitro fermentation of oat bran obtained by debranning with a mixed culture of human fecal bacteria

The prebiotic potential of oat samples was investigated by in vitro shaker-flask anaerobic fermentations with human fecal cultures. The oat bran fraction was obtained by debranning and was compared with other carbon sources such as whole oat flour, glucose, and fructo-oligosaccharide. The oat bran fraction showed a decrease in culturable anaerobes and clostridia and an increase in bifidobacteria and lactobacilli populations. A similar pattern was observed in fructo-oligosaccharide. Butyrate production was higher in oat bran compared to glucose and similar to that in fructo-oligosaccharide. Production of propionate was higher in the two oat media than in fructo-oligosaccharide and glucose, which can be used as energy source by the liver. This study suggests that the oat bran fraction obtained by debranning is digested by the gut ecosystem and increases the population of beneficial bacteria in the indigenous gut microbiota. This medium also provides an energy source preferred by colonocytes when it is metabolized by the gut flora.

In vitro fermentation of oat and barley derived beta-glucans by human faecal microbiota

Fermentation of beta-glucan fractions from barley [average molecular mass (MM), of 243, 172, and 137 kDa] and oats (average MM of 230 and 150 kDa) by the human faecal microbiota was investigated. Fractions were supplemented to pH-controlled anaerobic batch culture fermenters inoculated with human faecal samples from three donors, in triplicate, for each substrate. Microbiota changes were monitored by fluorescent in situ hybridization; groups enumerated were: Bifidobacterium genus, Bacteroides and Prevotella group, Clostridium histolyticum subgroup, Ruminococcus-Eubacterium-Clostridium (REC) cluster, Lactobacillus-Enterococcus group, Atopobium cluster, and clostridial cluster IX. Short-chain fatty acids and lactic acid were measured by HPLC. The C. histolyticum subgroup increased significantly in all vessels and clostridial cluster IX maintained high populations with all fractions. The Bacteroides-Prevotella group increased with all but the 243-kDa barley and 230-kDa oat substrates. In general beta-glucans displayed no apparent prebiotic potential. The SCFA profile (51 : 32 : 17; acetate : propionate : butyrate) was considered propionate-rich. In a further study a beta-glucan oligosaccharide fraction was produced with a degree of polymerization of 3-4. This fraction was supplemented to small-scale faecal batch cultures and gave significant increases in the Lactobacillus-Enterococcus group; however, the prebiotic potential of this fraction was marginal compared with that of inulin.

Interaction of heat-moisture conditions and physical properties in oat processing: II. Flake quality

Product quality is an important determinant of consumer acceptance. Consistent oat flake properties are thus necessary in the mill as well as in the marketplace. The effects of kilning and tempering conditions (30, 60 or 90 min at 80, 95 or 110 degrees C) on flake peroxidase activity, size, thickness, strength and water absorption were therefore determined. After kilning, some peroxidase activity remained but steaming and tempering effectively destroyed the activity of these enzymes. Thus the supposed protective effect of kilning or groat durability was not confirmed. Kilning resulted in an increase in flake specific weight, but no other significant effect on flake quality was observed. Tempering time and temperature interacted significantly to produce complex effects on flake specific weight, thickness and water absorption. Flake thickness and specific weight were significantly correlated (r = 0.808, n = 54). Longer tempering times resulted in an increased fines' fraction, from 1.45% at 30 min to 1.75% at 90 min. It is concluded that whilst kilning has little effect on flake quality, the heat treatment immediately prior to flaking, can be used to adjust flake quality independently of flake thickness.