Terms Of Metabolizable Energy Research Articles

Metabolic assessment of biological mechanisms underlying agroecological systems: The example of parasite dilution and forage niche sharing in mixed-grazing

CONTEXTMixed-grazing by sheep and cattle is the simultaneous or sequential grazing of a pasture by the two species. It is an agroecological practice known to improve lamb liveweight gains through parasite dilution (PD) and/or forage niche sharing (FNS). OBJECTIVEWe assessed the combined and relative strengths of the two mechanisms by developing a metabolic approach (French uplands context). METHODSWe used recently published equations to model the infection cost of gastrointestinal nematodes in metabolizable energy (ME), and crude protein (CP). By comparing infection levels in mixed and monospecific grazing, we quantified the gains of PD in ME and CP. We also used feed value tables to assess the gains in ME and CP resulting from FNS sheep diet improvement. We interpreted these gains in light of ME and CP requirements of lambs. We applied this approach to the dataset of a mixed-grazing experiment, involving sheep monospecific grazing and mixed sheep/cattle grazing, without veterinary treatment. We also applied it to a generic situation where we studied the relative gains in ME and CP, along gradients of increasing strength of PD and FNS. RESULTS AND CONCLUSIONSThe approach applied to our experimental data revealed that i) infection by gastrointestinal nematodes can represent 100% of ME and 57% of CP requirements in monospecific grazing, ii) mixed-grazing can reduce these costs to 23% and 12%, respectively and iii) PD was more important than FNS in terms of ME gains, whereas the opposite was true for CP. However, meeting CP requirements was less constraining than meeting ME requirements on the studied grassland type, which puts into perspective the importance of CP gains. With the generic approach, most of the modelled situations also identified PD as the main mechanisms of ME gain (79%), whereas it was FNS for CP (70%), with the same observation that CP requirements were less difficult to meet. Both approaches suggest that in our modelled context, PD matters more often than FNS in mixed-grazing, due to the greater difficulty in meeting ME requirements. SIGNIFICANCEWe proposed a novel approach to assess the roles of two biological mechanisms of contrasting nature, with the help of common metrics. This approach made it possible to evaluate their combined and relative strength. It has the potential to improve our understanding of the impact of interacting biological mechanisms involved in agroecological grazing systems, and identify prominent ones.

In Vitro Studies on Rumen Fermentation and Methanogenesis of Different Microalgae and Their Effects on Acidosis in Dairy Cows

Two in vitro studies were carried out on nonlactating dairy cows. Experiment 1 compared the methanogenesis and rumen fermentation parameters of various microalgae (Spirulina platensis, Chlorella vulgaris, and Schizochytrium spp.) and protein feeds (sunflower meal, soybean meal, and alfalfa hay) with monensin (MON). Rumen fermentation parameters were determined by an in vitro gas production system. Experiment 2 compared the ability of three microalgae to prevent acidosis. They were tested for 6 h against oat straw (100 mg) and MON (12 g/mL) to ameliorate ruminal acidosis caused by the addition of glucose (0.1 g/mL) as a fermentable carbohydrate with rumen fluid. In experiment 1, there were variations in the nutrient content of microalgae and protein sources. The dry matter content of the substrates ranged from 90 to 94%, and the organic matter content ranged from 82 to 88%, with Schizochytrium spp. having the highest. Protein content in algae and protein feeds ranged from 18–62% of dry matter (DM) to 16–48% DM, with S. platensis and C. vulgaris having the highest. The ether extract of Schizochytrium spp. (45.5% DM) was the highest of any substrate. In vitro rumen fermentation revealed that protein feeds increased the cumulative gas production at the highest level while MON caused a decrease. Ruminal pH was found to be higher in MON (6.95) and protein feeds (6.77–6.81) than in algae (6.37–6.50). In addition, in terms of metabolizable energy and digestible organic matter, protein feeds outperformed algae. The MON produced the least amount of methane (CH4) of any substrate, but Schizochytrium spp. demonstrated potential for CH4 reduction. In these groups, the decrease in CH4 production was accompanied by a decrease in total volatile fatty acids, acetate, and the acetate-to-propionate ratio, but an increase in propionate. Experiment 2 revealed MON as the most effective cure for controlling acidosis. However, C. vulgaris and Schizochytrium spp. had an effect on medium culture pH and demonstrated potential for acidosis prevention. This study found that algae can influence ruminal fermentation, have the potential to reduce CH4 production, and may reduce acidosis incidence rates. These assumptions, however, must be validated through in vivo studies.

Energy intake and nutritional balance of roe deer (Capreolus capreolus) in special Bavarian landscapes in southern Germany

Context Irrespective of the fact that the European roe deer (Capreolus capreolus) occurs from the Mediterranean to north of the Arctic Circle and is one of the most abundant and widespread species, roe deer are fed in winter in Germany and Austria. Hunters justify the supplementary feeding with the argument that roe deer do not find sufficient high-quality food in our landscape and they would have to starve in winter. Aims Our aim was to measure the quality and energy content of the browsed roe deer diet (in terms of metabolisable energy, ME) and the daily energy intake by roe deer. Methodology Between 2017 and 2019, rumenreticula of 629 roe deer were collected from five extreme habitats in Bavaria. Samples were examined by standard methods of dietary analysis, such as in vitro ruminal fermentation, crude nutrient analysis and the analysis of neutral/acid detergent fibre and acid detergent lignin. In addition, data on body condition and age were collected for each roe deer. Key results The diet consumed by roe deer has an energy density between 5.1 MJ/kg dry matter (DM) and 6.1 MJ/kg DM on average. Crude fibre contents in the diet varied between 20% and 38% DM. Roe deer compensate for lower energy densities in vegetation by consuming more diet. Across all habitats, adult consumed an annual mean of between 10.6 and 12.9 MJ ME/day. Conclusions Roe deer find sufficient high-energy food in all landscape types. They consume and can utilise raw fibre to the same extent as do red deer or mouflon. Differences in energy density among habitats result from carbohydrate content and are compensated for by more food intake. Energy deficits in roe deer could not be detected in any habitat at any time. Implications Roe deer do not need supplementary feeding in any habitat. Supplementary feeding leads to browsing damage because of the lack of raw fibre in the feed.

Determination of Nutritive Value and In Vitro Gas Production of Some Triticale Varieties.

The aim of this study to determine the chemical composition, in vitro total gas production (TG), metabolisable energy (ME) and organic matter digestibility (OMD) of grains belonging to different triticale varieties. Crude ash (CA) contents of varieties range from 2.05 to 2.30%, ether extract (EE) contents of the varieties is range of 1.82%-3.00%, crude protein (CP) content of varieties between 9.44 and 13.25%, acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents of were range of 2.51-4.50% and 15.15-17.65%, respectively. In vitro total gas production of varieties was between 57.59 and 62.51, ME and OMD also between 11.69-12.55 Mj kg-1 DM and 78.06-82.24%, respectively. While Bera and Tatlıcak 97 leap out in terms of ME, Bera variety leap out in terms of OMD. Effects of varieties on chemical composition, in vitro TG, ME and OMD of triticale grains were found to be significant (P<0.05). According to chemical composition and fermentation parameters, Bera variety, has high values in terms of CP, ME and OMD can be recommended for grain production.

The Estimation of Metabolizable Energy Using an Analysis of Ruminal Fermented Gas Production in Protected Lemuru Fish Oil

This study has purpose to estimate the metabolic energy of protected lemuru fish oil using the rumen fermentation gas production analysis. This study applied a combination of treatments, which is differences in NaOH concentrations and drying methods on the total gas production in vitro. The gas production was determined at the incubation of 0, 2, 4, 8, 12, 24, 48, and 72 hours. This study applied a Completely Randomized Design on 3x2 factorial. The parameters observed included the total gas production, the data were tested using an analysis of variance and continued with the Duncan test. The results of this study indicated that at the incubation time of 48 hours and 72 hours, there was no difference in the interaction between the NaOH concentration and the drying method on the total gas production, and there was a significant difference between the NaOH concentration and the drying method in terms of metabolizable energy (ME). The results of the highest ME value in the protected lemuru fish oil were 10% NaOH concentration and the sun drying method was 4.56 MJ/Kg BK, it can be concluded that the ME estimation is influenced by the yield of incubation gas production for 24 hours.

ENERGY REQUIREMENTS OF YOUNG EWES FED GUINEA GRASS (PANICUM MAXIMUM) FOR MAINTENANCE AND GAIN

Energy requirement for maintenance and weight gain of non-lactating, non-pregnant West African Dwarf ewes were determined by using equation of the form DOMI = aw0.75 + bG........ (1) where, DOMI = Digestible Organic matter intake (kg/day), W = Liveweight of ewe (kg), G = Liveweight gain of ewe (kg/day), a = DOMI requirement per kg of Wkg0.75, b = DOMI requirement for each kilogram liveweight gain. The regression equation obtained was DOMI = 0.0385Wkg 0.75 + 1.54G........(2). The values of DOM required per kilogram of Wkg0.75 and for each kilogram of liveweight gain, were 0.0385 and 1.54kg respectively. In terms of Metabolizable energy (ME) equation (2) can be written as follows: ME = 523.50Wkg0.75 + 20940.92G........(3) Values of ME required per kilogram of Wkg0.75 and each kilogram of liveweight gain were 523.5 and 20940.92 KJ from equation 3. These results are comparable to those obtained for other breeds of sheep of both temperate and tropical origin.

Nutrient and Mineral Contents, and In vitroDigestibility of Kermes Oak (Quercus cocciferaL.) and Mock Privet (Phillyrea latifoliaL.)

This study was conducted to exhibit the importance of kermes oak (Quercus coccifera L.) and mock privet (Phillyrea latifolia L.) in the grazing system and animal feeding. For this purpose, the leaves of these two evergreen shrubs were harvested by hand-clipping in their early vegetative stages at Sarkoy, Tekirdag, Turkey, in April 2019. The nutrient and mineral contents and in vitro digestibility of kermes oak and mock privet was determined by using in vitro gas production technique. In this study, it was found that there was a statistically significant difference between the kermes oak and mock privet in terms of the contents of dry matter, crude ash, crude cellulose, neutral detergent fiber, acid detergent fiber and acid detergent lignin, and the minerals of zinc, copper, iron, and potassium (p<0.05). Furthermore, it has been observed that these two shrub plants yielded different values in terms of metabolizable energy and organic matter digestibility (p<0.05). In this study, the time-dependent mean gas production of the two evergreen shrubs was found to be significant at all times except the 96th hour; and gas production kinetics made a significant difference in b, the volume of the gas production from slowly fermentable (p<0.05). The volume of the gas production from slowly fermentable (b) was found to be higher in the mock privet than the kermes oak. Results derived from this study indicate that even the differences between the kermes oak and mock privet in terms of nutrient and mineral contents, both shrubs might be used more adequately as an alternative feed source during the grazing season where they are widely distributed.

Modelling the production impacts of a widespread conversion to organic agriculture in England and Wales

We assess the production impacts of a 100% conversion to organic agriculture in England and Wales using a large-scale linear programming model. The model includes a range of typical farm structures, scaled up across the available land area, with the objective of maximising food production. The effects of soil and rainfall, nitrogen (N) supply/offtake and livestock feed demand are accounted for. Results reveal major reductions in wheat and barley production, whilst the production of minor cereals such as oats and rye increase. Monogastric livestock and milk production also decreased considerably, whilst beef and sheep numbers increased. Vegetable production was generally comparable to that under conventional farming. Minimising the area of fertility building leys and/or improving rates of N fixation increased the food supply from organic agriculture at the national level. The total food output, in terms of metabolisable energy, was 64% of that under conventional farming. This would necessitate substantial increases in food imports, with corresponding expansion of cultivated agricultural land overseas. Significant changes in diet and reductions in food waste would be required to offset the production impacts of a 100% conversion to organic farming.

Effect of Maleic Acid on Nutritive Value, Carotenoids Content and In vitro Digestibility of Maize Silage

This study aimed to determine the effects of supplementation of maleic acid (MA) on the silage characteristics, nutritive value, carotenoids contents, and in vitro digestion attributes of maize silage. Maize herbage was ensiled either without (control group: MA0) or with three different doses of 1.0 (MA1), 2.0 (MA2), and 3.0 (MA3) percent (w/w) of the fresh material for 60 days. Supplementation of MA did not change the dry matter (DM), ash, crude protein (CP), ether extract (EE), acid detergent fibre (ADFom), acid detergent lignin (ADL) or TDN contents of the silage. In addition, neutral detergent fibre (aNDFom) content decreased (P<0.001) linearly by the increasing dose of maleic acid dose. However, relative feed value, relative forage quality and non-structural carbohydrate of maize silage increased linearly (P<0.001) by MA. Neither the in vitro total gas and methane production nor the nutritive value of the silage in terms of metabolisable energy (ME), net energy lactation (NEL) and organic matter disappearance (OMd) changed due to maleic acid supplementation. However, the supplementation of MA to maize herbage at ensilaging stage decreased (P<0.01) its α-carotene, β-carotene, γ-carotene, lycopene and zeaxanthin contents in a linear manner with a concomitant increase (P<0.01) in its lutein and total carotenoids contents. It is concluded that maleic acid addition to maize forage at ensiling stage increased the total carotenoids content of the silage without influencing any of the nutrient characteristics.

Evaluation of Artichoke Bracts as a Potential Source of Bioactive Compounds, Bio-ethanol Production and Livestock Feeding

Recycling of lignocellulosic agro-industrial residues waste is the key of the environmental sustainability. So, the goal of the present study was to utilize artichoke (Cynara cardunculus L.) bracts as a potential source of bio-active compounds or as a carbon source during bio-production of ethanol and to evaluate its nutritive value for livestock feeding by using in vitro gas production technique. The chemical composition, phenolic compounds, and radicals scavenging property of extracts were determined. Silage production and acid hydrolysis on conversion of lignocellulosicartichoke was studied. Also, the acid hydrolysate of lignocellulosic components as a carbon source was investigatedduring bio-production of ethanol using Saccharomyces cerevisiae and simultaneous saccharification fermentationprocess. The obtained results revealed variation in proximate composition and mineral content among treatments of artichoke bracts used here. The blanching processing of artichoke bracts had higher total phenolic content (935.43 mg GAE /100 g DW) and 89.64% inhibition of DPPH radical with an IC50 value of 6.23 mg/ml. The highest reducing sugar content was obtained by using sulphuric acid (3%) for 20 min at 120°C. Fermentation of the hydrolysates gave the highest ethanol yield of (10.02 g/L), which corresponds to volumetric productivity of ethanol being 1.52 g /L/h with fermentation efficiency of 97.39% and biomass of 4.64 g/L after 48 hr. The results of the present study suggest that adding sugar beet molasses to the fermentation medium enhanced production of bio-ethanol (14.01g/L). The resultsalso showed that the nutritional value of the artichoke bracts is similar to that of good roughage as hay in terms of metabolizable energy (8.42 MJ/kg DM), net energy (3.15MJ/kg DM), short chain fatty acids (99.48 mM), microbial protein synthesis (76.49 g/kg) and organic matter digestibility (63.41 %).

THE CHEMICAL COMPOSITION AND NUTRITIVE VALUE OF Brachiaria GRASS CULTIVARS AT KATUMANI DRYLAND RESEARCH STATION IN SOUTH EASTERN KENYA

The study was conducted at Kenya Agricultural and Livestock Research Organisation, Katumani, Machakos to evaluate the herbage quality of Brachiaria grass cultivars in semi arid regions of Eastern Kenya. Brachiaria cultivars namely B. decumbens cv. Basilisk, Brachiaria hybrid Mulato II, four Brachiaria brizantha cultivars Marandu, Xaraes, Piata, MG4 and Brachiaria humidicola cv Llanero were assessed with reference to their chemical and nutritive composition at 22, 24 and 28 weeks post seedling emergence. Rhodes grass (Chloris gayana cv KATR3) and Napier grass (P. pupureum cv. Kakamega I) were included as controls. There were significant differences (p&lt;0.05) among the cultivars for crude protein, crude fibre (NDF, ADF and ADL) Ash, Calcium, Phosphorus, Dry Matter Digestibilty and Metabolisable energy during the the week 22 and 24 post seedling emergence harvest. At week 28 harvest interval, however, ADL values for all the cultivars were similar and only Marandu was significantly different (p&lt;0.05) in terms of metabolizable energy from the rest. The mean CP content of the grasses decreased from 11.1% at week 22 to 6.3% at harvest week 28 harvest intervals. MG4, Mulato II and Xaraes were the only grasses able to meet minimum CP (7.0%) requirement for rumen microbial function throughout the harvest period. Ash and phosphorus values decreased whereas Calcium content increased for all the cultivars during the harvest intervals, with Mulato II recording the highest ash (15%) content during this period. Chloris gayana KATR3 recorded highest average NDF (72.9%), ADF (48.1%) and ADL (6.1%) content during this period. Xaraes, Marandu and Mulato II were the only cultivars able to achieve the highest metabolizable energy of 7.0 MJ/kg DM recorded for the grass cultivars throughout the harvest intervals. These results indicate that Brachiaria grasses can be a good source of forage for livestock and a boost to the forage resource base in the semi arid regions of Kenya. Further research is needed to quantify their productivity in both dry and wet periods and to assess the effect of feeding on animal production performance.

Screening for low Raffinose family oligosaccharides and low Phytic acid lines in macro mutant Urdbean (Vigna mungoL. Hepper)

Oligosaccharides are important component of urdbean in terms of metabolizable energy for monogastric animals and human. Sucrose, raffinose, stachyose and verbasecose are the four main oligosaccharides present in urdbean. Out of the four, only sucrose is nutritionally useful. When raffinose stachyose and verbascose are fermented by microbes present in the gut, the results are flatulence and discomfort, which ultimately lead to poor weight gain. The objectives of this work were to establish to identify low raffinose family oligosaccharide (RFO) and Low phytic acid (LPA) in macro mutants of TNAUCo (Bg) 6. The seeds of TNAUCo (Bg) 6 were treated with gamma rays (200Gy and 250Gy) EMS (15mM and 20mM). The frequency and spectrum of macro mutants different dose/concentration, number of chlorophyll mutants and Macro mutants observed. Chlorophyll mutants and viable mutants calculated based on the biological damage. The spectrum of chlorophyll mutants (Chlorina, Xantha, Albino and Viridis) and viable mutants (Tall and erect, dwarf, spreading, compact and bushy, crinkled and leathery, small leaf, big and broad leaf, narrow leaf, sterile, non flowering, pod and seed mutants) were observed in both generation. The spectrum of chlorophyll mutants increased with the decreased in dose of mutagen and increased with lower concentration. Total of 22 and 102 macro mutants were isolated from gamma ray and EMS treatments. Compare to all treatment 15mM of EMS treatments were establish more efficient in causing less biological injure and inducing highest amount of mutations. The total of 124 macro mutant three Low Verbascose mutant M2-F58 (0.06 mg/g), M2-F117 (0.13 mg/g) of 15mM, M2-F27 of 20mM (0.13 mg/g) and one low Phytate mutant in M2 -F37 of 15mM EMS (0.02 mg/g) were selected.

Estimating the balance between pasture feed supply and demand of grazing livestock in a farmlet experiment

Data from the Cicerone farmlet study were used to quantify the balance between pasture feed supply and the demand from grazing livestock, in terms of metabolisable energy (ME), on three differently managed farmlets (each of 53 ha) on the Northern Tablelands of New South Wales, Australia. Farmlet A had a high level of pasture renovation and higher soil fertility than the other two farmlets and employed flexible grazing management over eight paddocks. Farmlet B was designed to represent management ‘typical’ of the region and had the same grazing management and number of paddocks as farmlet A but moderate levels of pasture renovation and soil fertility. The third farmlet (C) had the same level of inputs as farmlet B but practised intensive rotational grazing over 37 paddocks. Regular measurements of the feed supply, namely herbage mass and quality, pasture growth and supplement fed and of feed demand were assembled to provide monthly estimates of the balance between feed supply and animal demand of all classes of livestock run on the experiment over its duration of 6.5 years. The significantly greater stocking rate, liveweight and reproductive rate of sheep reached on the higher input system (farmlet A) meant higher levels of ME were required to satisfy the nutritional demands of these animals. As only limited measurements were taken of animal intake, it was assumed that the supply of ME was derived from pasture growth and supplement fed. Using key livestock management dates and measurements of liveweights, the changes in the energy requirements of each class of animal were calculated and aggregated to provide an estimate of overall livestock energy demand over time. Subtracting the energy demand from the estimated energy supply provided a partial net energy balance. Measurements of the rates of change of green herbage during grazing events were found to be highly dependent on stock density with farmlets A, B and C recording rates of change of up to –50, –30 and –200 green DM/ha.day, respectively. Over a series of generally drier-than-average years, the ME supplied in pasture growth and through supplementation was at times inadequate to meet the energy demands of the livestock, resulting in periods during winter when the partial energy balance became negative. Similar feed deficits were observed for all three farmlets, suggesting that they were over-stocked to a similar extent. In spite of the divergence in the stocking rate supported by each farmlet, the similarity of the ME balances between farmlets suggests that no farmlet was subjected to bias because of decisions relating to feed supply and demand. The analyses presented suggest there is considerable potential for practical paddock and grazing management to be improved if more timely and regular assessments can be made of changes in the feed energy supply using satellite images of normalised difference vegetation indices and feed energy demand using calculations of the ME required by grazing livestock.

Efficiency of energy utilisation and voluntary feed intake in ruminants

Energy requirements of animals are most readily expressed in terms of net energy (NE), while the energy yield of feed is, at least initially, expressed in terms of metabolisable energy (ME). Energy evaluation systems ‘translate’ NE requirements into ME requirements (ME systems) or assign NE values to feeds (NE systems). Efficiency of ME utilisation is higher for maintenance than for production and the NE yield of a feed varies, therefore, with ME intake. In addition, energetic efficiency for maintenance and production is thought to be different for lactating and non-lactating animals and to be affected by diet quality. As a result, there are currently many national energy evaluation systems that are complex, differ in their approach and are, as a result, difficult to compare. As ruminants in most production systems are fed ad libitum, this is also the most appropriate intake level at which to estimate energetic efficiency. Analyses of older as well as more recent data suggest that ad libitum feeding (i) abolishes the effects of diet quality on energetic efficiency (almost) completely, (ii) abolishes the differences between lactating and non-lactating animals (almost) entirely and (iii) results in overall energetic efficiencies that are always close to 0.6. The paper argues that there is now sufficient information to develop an international energy evaluation system for ad libitum fed ruminants. Such a system should (i) unify ME and NE systems, (ii) avoid the systematic bias and large errors that can be associated with current systems (iii) be simpler than current systems and (iv) have as a starting point a constant efficiency of ME utilisation, with a value of around 0.6. The remarkably constant efficiency of ME utilisation in ad libitum fed ruminants could be the result of energetic efficiency as well as feed intake regulation being affected by the same variables or of a direct role of energetic efficiency in feed intake regulation. Models to predict intake on the basis of the latter hypothesis are already available for non-reproducing ruminants but remain to be developed for reproducing animals.

Methods for predicting the energy value of pet foods

The energy value of foods as well as energy requirements of dogs and cats is currently expressed in terms of metabolizable energy (ME). The determination of ME content of foods requires experimental animals and is too expensive and time consuming to be used routinely. Consequently, different indirect methods have been proposed in order to estimate as reliably an accurately as possible the ME content of pet food. This work analyses the main approaches proposed to date to estimate the ME content of foods for cats and dogs. The former method proposed by the NRC estimates the ME content of pet foods from proximal chemical analysis using the modified Atwater factors, assuming constant apparent digestibility coefficients for each analytical fraction. Modified Atwater factors systematically underestimate the ME content of low-fibre foods whereas they overestimate those that are high in fibre. Recently, different equations have been proposed for dogs and cats based in the estimation of apparent digestibility of energy by the crude fibre content, which improve the accuracy of prediction. In any case, whatever the method of analysis used, differences in energy digestibility related with food processing and fibre digestibility are unlikely to be accounted for. A simple in vitro enzymatic method has been recently proposed based in the close relationship that exist between energy digestibility and organic matter disappearance after two consecutive enzymatic (pepsin-pancreatin) incubation of food sample. Nutrient composition and energy value of pet foods can be also accurately and simultaneously predicted using near infrared reflectance spectroscopy (NIRS).

Improved soil and irrigation management for forage production 2. Forage yield and nutritive characteristics

Pastures are the main source of energy and nutrients for dairy cows in the irrigated dairy region of northern Victoria, yet annual production and utilisation of pasture have remained static over the last 20 years. Previous small plot research has shown that pasture yields can be increased through systems of soil modification that improve soil structure and alleviate limitations to root growth. We compared the yield and nutritive characteristics of 4 forage species [tall fescue (Festuca arundinacea), lucerne (Medicago sativa), phalaris (Phalaris aquatica) and perennial ryegrass (Lolium perenne)] on soils which had been modified using commercially-available equipment and using spray irrigation at 2 frequencies. In year 1 (2000–01), annual yields of the forages were tall fescue: 21.2 t dry matter (DM)/ha; lucerne: 20.5 t DM/ha; phalaris: 19.8 t DM/ha; and perennial ryegrass: 20.8 t DM/ha. In the second year of the experiment, annual yields averaged 28.9 t DM/ha for tall fescue, 26.1 t DM/ha for lucerne, 31.6 t DM/ha for phalaris and 23.2 t DM/ha for perennial ryegrass. There was no consistent response in yield of any species to soil modification. The improvements in soil structure achieved with soil modification were probably not large enough to result in yield responses. Yields were greater when frequently irrigated, with the exception of perennial ryegrass in the second year. Most of the yield benefit due to frequent irrigation was limited to the summer months. No yield data showed significant soil by irrigation frequency interaction. There were significant differences in forage nutritive characteristics between the 4 species. The lower crude protein content of lucerne would be at least partly due to the frequent application of nitrogen fertiliser to the grasses. Tall fescue usually had similar nutritive characteristics to perennial ryegrass in terms of metabolisable energy, protein and NDF. Phalaris had high fibre contents and low metabolisable energy in summer. We conclude that it is not feasible, at this time, to improve yields of irrigated forages through soil modification on a commercial scale.

Carbohydrases, protease, and phytase have an additive beneficial effect in nutritionally marginal diets for broiler chicks

To investigate the additive effects of xylanase, amylase, protease, and phytase in the diets of broiler chickens, a study was conducted using 1,152 growing broiler chicks (8 treatments with 12 replicate pens of 12 chicks). The birds were fed a corn/soybean-based negative control (NC) diet that was formulated to be nutritionally marginal in terms of metabolizable energy, Ca, and P. A nutritionally adequate positive control (PC) diet was fed for comparison. The NC diet was supplemented with phytase; a cocktail of xylanase, amylase, and protease (XAP); or a combination of phytase and XAP at 100 or 200 mg of each enzyme/kg (200 mg of XAP/kg provided a guaranteed minimum of 300 U of xylanase, 400 U of amylase, and 4,000 U of protease/kg; 200 mg of phytase/kg provided a guaranteed minimum of 1,000 U of phytase/kg). Growth performance, ileal digestible energy (IDE), and the digestibility coefficients of N, Ca, P, and DM were calculated. Individually and in combination, both phytase and XAP improved (P < 0.05) gain-to-feed ratio compared with the NC diet, particularly at the highest inclusion concentration. Body weight gain followed a similar trend, showing an improvement of approximately 6 to 7% with either enzyme individually and a 14% improvement with a combination of phytase and XAP. The effect of enzymes on IDE and nutrient digestibility coefficients was not as marked, but a 165 kcal/kg reduction in IDE was noted between the NC and PC diets, and a combination of phytase and XAP improved IDE by >100 kcal/kg. It can be concluded that the use of phytase and XAP individually in a corn/soybean meal-based diet is effective in improving nutrient digestibility and performance of broilers fed nutritionally marginal diets. Furthermore, there may be an additive effect of phytase and XAP on broiler performance, giving a cost-effective nutritional strategy for the profitable production of poultry products.

Chemical Composition and Its Relationship to In vitro Gas Production of Several Tannin Containing Trees and Shrub Leaves

The aim of this experiment was to determine the chemical composition of six commonly utilized fodder trees and shrub species in Turkey, namely Glycrrhiza glabra L, Arbutus andrachne, Carpinus betilus, Juniperus communis, Quercus libari L and Pistica lentiscus and its relationship with gas production and estimated parameters when incubated with rumen fluid in vitro. There were significant (p<0.001) differences between leaves in terms of crude protein (CP), acid detergent fiber (ADF), total condensed tannin (TCT), bound condensed tannin (BCT) and soluble condensed tannin (SCT). Crude protein contents ranged from 5.74% (Juniperus communis) to 12.59% (Glycrrhiza glabra L). Acid detergent fiber contents ranged from 25.14% (Glycrrhiza glabra L) to 39.23% (Juniperus communis). Total condensed tannin (TCT) contents of leaves ranged from 4.34% (Quercus libari L) to 20.34% (Juniperus communis). Acid detergent fiber (ADF) and total condensed tannin contents of leaves were negatively correlated with gas productions and some estimated parameters. Potential gas productions (A) of Glycrrhiza glabra L, Arbutus andrachne, Quercus libari L and Pistica lentiscus were significantly (p<0.001) higher than those of Carpinus betilus and Juniperus communis whereas gas production rate (µ24) of Pistica lentiscus was significantly (p<0.001) higher than the others. Time (h) to produce 50% of total gas pool size (T50) of Juniperus communis was significantly (p<0.001) lower than that of Carpinus betilus whereas time (h) to produce 90% of total gas pool size (T90) of Juniperus communis was significantly lower than the others except for Pistica lentiscus. The metabolizable energy (ME) contents of leaves ranged from 8.86 to 10.39 MJ kg -1 DM. The results obtained in this study suggested that browse species had a significant effect on chemical composition, gas production and estimated parameters of leaves. Leaves from Glycrrhiza glabra L with a considerable amount of CP had a high rank value in terms of ME. Therefore leaves from Glycrrhiza glabra L may have a high potential value for small ruminant animals in terms of rumen and whole digestibility. Leaves from other species studied require protein supplementation when they are the only feed consumed by ruminant animals. (Asian-Aust. J. Anim. Sci. 2005. Vol 18, No. 2 : 203-208)

Oats and naked oats: recent studies of composition, digestibility and energy value for ruminants

Oats constitute a small and decreasing share of the cereals grown and utilized in the United Kingdom. Compared with the major cereals wheat and barley, oats are perceived to have a low nutritive value in terms of metabolisable energy (ME). Unlike other cereals, the husk remains attached to the oat kernel at harvesting, hence increasing the fibre or cell wall content of the grain.The proportion of kernel to husk which largely determines the nutritive value of the oat grain is dependent on variety, environment and season.Previous values for oats (MAFF 1986) were based on a study of 16 samples at the Rowett Research Institute (RRI 1976) in which most were spring sown varieties with low oil contents. The aim of this present work was to examine currently recommended winter varieties and also to study naked oats. These differ from traditional husked oats by having a thin, non-lignified husk from which the grain threshes free.

Recent developments in predicting the nutritive value of compound feeds for ruminants

The nutritive value of compound feeds for ruminants has been classically described in terms of starch equivalent for energy and digestible crude protein for the protein fraction. Over the last ten years there has been a move to describe energy in terms of metabolisable energy and protein in terms of rumen degradable (RDP) and rumen undegradable protein (UDP). Both of these descriptions involve measurements on animals in order to derive values for individual ingredients to be used in compound feeds. The assumption is then made that these individual ingredient values are additive when the ingredients are used in the compound.Metabolisable energy is measured in animals kept in calorimetric chambers or metabolic crates, in the latter case energy loss in the form of methane is assumed to be constant. However, data from the Rowett indicates that this is not the case, losses varying from 1.1-2.5 MJ/kg DM (Table 1). This inaccuracy can have a dramatic economic affect in feed formulation for 1MJ difference is worth £7/tonne of ingredient.