The intake of steers and heifers fed on mixtures of alkali-treated or untreated straw with grass silage

Two experiments were made to investigate the intake of cattle when offered straw and silage mixtures.In a trial of changeover design 12 Friesian castrates (steers) were offered five diets. These were grass silage alone or mixed with untreated or NaOH treated straw supplying 20 or 40% of the total dry matter. The addition of 20% straw to the diet significantly reduced dry matter intake, and a further reduction occurred at 40%. Treating the straw with NaOh did not increase dry matter intake but led to an associated increase in digestible organic matter intake.Twelve Ayrshire heifers were given four diets in a trial of changeover design. The diets were silage only and three straw : silage mixtures in which straw provided 40% of the dry matter. The straws were untreated, NaOH treated or KOH treated. Untreated straw markedly depressed dry matter intake; NaOH raised the digestibility of straw and thus increased digestible organic matter intake significantly. The dry matter intake of the heifers was much greater than anticipated with the KOH treated straw : silage mixture and was similar to that achieved with silage only.     

Cellulase insoluble fibre as a measure of unavailable organic matter in cattle compounds containing alkalitreated straw

A laboratory method for determination of fibres insoluble by cellulase is suggested as a routine analysis for cattle compound feeds with varying proportion and quality of chemically treated straw and other fibrous components, in order to measure whether actual energy content corresponds to that declared.By a two-step analytical procedure, the total fibre is isolated by boiling with neutral detergent solution for 1 h, which removes the readily soluble carbohydrates, proteins and fat. By incubation of the isolated fibre in a solution of buffers and a commercial cellulase reagent for 48 h at 40°C the digestible fibre is removed. The organic matter in the residue, which is termed cellulase insoluble fibre (CIF), is a measure of unavailable organic matter for ruminants.The CIF content, total NDF and proximate constituents were determined in 47 compounds of extreme properties. Compared with digestibility in vitro (IVDOM), more organic matter was dissolved by the CIF-analyses in highly digestible feeds and less in feeds with low digestibility (IVDOM + fat = 87 ? 0.70 CIF).     

Influence of dietary fibre on nutrient digestibility and energy utilisation in growing pigs fed diets varying in soluble and insoluble fibres from co-products

The co-products from the industry are used to reduce costs in pig diets. However, the co-products used in pig diets are limited because of a high fibre content which is not digested by endogenous enzymes and is resistant to degradation in the small and large intestines. The aim of this study was to investigate digestibility of nutrients and energy, and energy utilisation in pigs fed diets with various soluble and insoluble dietary fibre (DF) from co-products. The experiment was performed as a 4 × 4 Latin square design (four diets and four periods) using four growing pigs (66.2 ± 7.8 kg) surgically fitted with a T-cannula in the end of the small intestine. The pigs were fed four experimental diets: low-fibre control (LF), high-fibre control (HF), high-soluble fibre (HFS) and high-insoluble fibre (HFI) diets. The apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of ash, organic matter, CP, fat, carbohydrates, starch and non-starch polysaccharides (NSP) divided into cellulose and soluble and insoluble non-cellulosic polysaccharide residues were measured using chromic oxide as marker. The recovery of total solid materials, organic matter and total carbohydrates in ileal digesta in pigs fed the HF and HFS diets was higher than in pigs fed LF and HFI, whereas recovery of organic matter and total carbohydrates in faecal materials in the HFS diet was lowest (P < 0.05). AID of organic matter, total carbohydrates and starch was lowest for HFS diet (P < 0.05). ATTD of organic matter and CP was higher for LF diet compared with other diets (P < 0.05), whereas total NSP, cellulose and non-cellulosic polysaccharides residues were highest for HFS diet (P < 0.05). Lactic acid in ileal digesta was influenced by dietary composition (P < 0.05) whereas neither type nor level of DF affected short chain fatty acids. The digestible energy, metabolisable energy, net energy and retained energy intake were similar among diets without influence of DF inclusion (P > 0.05). The metabolisable energy:digestible energy ratio was lower when feeding the HFS diet because of a higher fermentative methane loss. Faecal nitrogen and carbon were positively correlated with DM intake and insoluble DF in the diets (P < 0.05), but nitrogen and carbon (% of intake) were similar among diets. The present findings suggest that high-DF co-products can be used as ingredients of pig diets when features of DF are considered.     

The chemical composition of Phyllanthus discoideus and its effect on the ruminal ammonia and volatile fatty acid concentration when fed to west african dwarf sheep

The feeding value of Phyllanthus discoideus (also called Margaritaria discoidea) leaves was evaluated using eight two‐year‐old West African Dwarf sheep fed natural grass hay. Four of the animals were fistulated ruminally and used for ammonia and volatile fatty acid determination in the fluid. Dried leaves of Phyllanthus discoideus were offered at two levels (25% and 50% of DMI, diets D25% and D50%, respectively) as supplements to the basal hay diet. The CP content of the control, D25% and D50% diets were 11.5, 12.6 and 13.6%, respectively, and their digestible energy amounted to 58.2, 61.1 and 56.9%, respectively. Rumen liquor was sampled one hour before and one, three and five hours after the morning feeding.

Sheep fed the control diet had a higher ruminai ammonia concentration than those fed diet D25%. Similarly, ruminai ammonia concentration was higher in sheep fed the control diet than those fed the diet D50%. Five hours after feeding the ruminai ammonia concentration was significantly lower than one hour after feeding.

The VFA concentrations in rumen fluid of sheep fed the control diet was inferior to those fed diets D25% and D50%. Sheep fed diet D50% showed significantly higher VFA concentrations than those fed diet D25%. Digestibility of organic matter and digestible energy did not show any significant difference. However, a marginal increase in organic matter digestibility of 3.5% was observed in diet D25% compared with the control diet. There was no significant difference in the N‐digestibility in sheep fed the control, D25% and D50% diets. Nevertheless, a marginal improvement in N‐digestibility (1.5%) and N‐retention (2.7%) was observed with the highest level of Phyllanthus discoideus (D50%).

In conclusion, Phyllanthus discoideus appears as a particularly valuable feedstuff because it contains low levels of condensed tannins (12.8 g/kg), high CP content (156 g/kg) and a relatively high GE content (19.3 kJ/gDM). Although the improvement in N‐digestibility and N‐retention were only marginal the feeding of Phyllanthus discoideus could be justified under extreme shortage of feed resources during dry season. It should also be mentioned that a much more pronounced effect by supplementation with Phyllanthus discoideus could be expected when poor quality grass hay prevalent in West Africa during the dry season is fed. Phyllanthus discoideus could serve as a supplement to poor quality grass at 25% to 50% of supplementation.     

The nutritional value for sheep of molasses and condensed molasses solubles

The nutritional value of cane molasses and condensed molasses solubles (CMS, a highnitrogen by-product from the fermentation of beet molasses) was studied in two metabolism experiments with sheep.Nitrogen balance and the apparent digestibility of dry matter, organic matter, ether extract and acid detergent fibre in a barley-based control diet were not affected when 10 or 20% barley dry matter was replaced by either molasses or CMS dry matter. The digestibility of crude protein was significantly increased by CMS, because it increased the crude protein content of the rations. There was a positive linear relationship between crude protein and digestible protein as a percentage of the dry matter. The digestibility of nitrogen-free extract was depressed by the inclusion of molasses or CMS. Digestibility of energy was not significantly influenced by the inclusion of molasses at 10 or 20% or CMS at 10% but was depressed by the inclusion of CMS at 20%. The digestible energy of molasses was 82% of that of barley and the digestible energy of CMS was 84% of that of molasses.The extent of fermentation of ration components was studied in sheep with rumen and duodenal re-entrant cannulae. Although the apparent digestibility of dry matter, organic matter and gross energy was not affected by 20% molasses or CMS, the concentration of butyric acid in the rumen liquor was significantly increased at the expense of propionic acid. The concentration of ammonia in the rumen was elevated by high nitrogen intake. High concentrations of ammonia in the rumen liquor caused proportional excretion of nitrogen in urine.     

Influence of dietary fibre level and pelleting on the digestibility of energy and nutrients in growing pigs and adult sows

Two experiments were carried out to investigate the effect of pelleting on the apparent total tract digestibility (ATTD) of energy and nutrients according to the dietary fibre (DF) level in growing pigs (experiment 1) and in adult sows (experiment 2). Four diets based on wheat, barley, maize and soybean meal and supplemented with increased contents of a mixture of wheat bran, maize bran, soybean hulls and sugar beet pulp (116, 192, 268 and 344 g NDF/kg dry matter (DM) in diets 1 to 4) were tested. In experiment 1, 32 growing pigs (62 kg average BW), in two replicates and according to a factorial design, were fed one of the four diets, either as mash or as pellets. The digestibility of energy, organic matter (OM) and all nutrients decreased with DF increasing for both feed forms; the reduction was about 1% for each 1% NDF increase in the diet (P < 0.001). Pelleting improved moderately the digestibility of energy and OM (+1.5% and +1.0%, respectively; P < 0.05) in connection with greater DF (+5%; P < 0.05) and fat digestibility (+25%). Thus, pelleting improved the digestible energy content of diets on average by 0.3 MJ/kg of feed DM (P < 0.01). In experiment 2, four adult dry sows (235 kg average BW) were used in a 4 × 4 Latin square design and fed the four diets used in experiment 1 as pellets. The digestibility of energy, OM and macronutrients also decreased with DF increase (P < 0.001; -0.4% per 1% increase of dietary NDF for energy) while the digestibility of DF (i.e. crude fibre (CF) or ADF) increased (P < 0.001) or remained at a high level. In conclusion, increasing DF in diets decreases the digestibility of nutrients and energy in pigs and in sows. Although positive, the pelleting impact is minor on the energy and nutrients digestibility of fibre-rich diets in growing pigs, even in high-DF diets.     

Measurement and prediction of digestibility of forage maize in The Netherlands

Results of digestibility trials on fresh and ensiled maize (aerial parts) were analysed and compared with laboratory data.

Digestibility of the organic matter of ears was almost constant at 84–85%. Digestibility of organic matter of stover showed great variation. Variation between animals in apparent digestibility of organic matter was greater for maize diets than for diets based on grass products. Most of the differences between animals were caused by differences in the digestion of cell walls. When the true digestibility of cell contents was assumed to be complete, endogenous excretion was, on average, only 7% with respect to organic matter intake, and seemed dependent on digestibility of organic matter.

Prediction of apparent digestibility was more accurate with digestibility in vitro than with crude fibre, although for maize silage, significant relationships were found between crude fibre content and digestibility of organic matter. Standard deviation of organic matter digestibility between lots of fresh and ensiled maize grown on commercial farms amounted to only about 1.2 –2%. As this was only twice the accuracy of digestibility in vivo with four animals, fixed values will be presented to farmers, possibly corrected for year, hybrid selection and cropping practice.     

Comparison of laboratory methods for predicting the organic matter digestibility of forages

Seven laboratory methods for predicting organic matter digestibility were tested and compared on 42 samples of grass hay, 56 of silages and 39 of pelleted forages and byproducts. For all samples digestibility in vivo was determined with wethers fed at a maintenance level. The methods investigated were: tabular digestibility coefficients, Weende components, cell wall components, summative equations (Van Soest), true organic matter digestibility in vitro (Van Soest), digestibility in vitro (Tilley and Terry) and nylon bag digestibility.None of the purely chemical procedures nor the tabular digestibility coefficients were sufficiently accurate for a practical prediction of organic matter digestibility. Considerably better results were obtained with methods using living rumen micro-organisms. The best results were obtained with the nylon bag technique, but digestibility in vitro, measured by the two-stage technique, also gave accurate predictions of digestibility.     

Foraging strategy of cattle in patchy grassland

We tested several strategies of foraging that grazing herbivores may adopt in a patchy habitat in relation to energy intake. The patch selection of cattle was investigated in an Agrostis/Festuca grassland and in a Lolium grassland in 13 observation periods over 2 years. Both grasslands were stocked with five yearling steers. Bite counts were made on patches of different vegetation structure: short, tall and mature stemmy grass. Bite size of each patch category was determined by hand-plucking. Samples of patch types were analysed for organic matter digestibility, as a measure of energy content. There was a large seasonal variation in relative patch cover and in forage characteristics. However, the differences between patches in bite size, bite rate and digestibility were consistent over time. In short patches digestibility was high, bite size was low and bite rate was high compared to stemmy patches. In tall patches digestibility was only little lower than in short patches and bite size and bite rate were intermediate between short and stemmy patches. The steers selected the short and tall patches over the stemmy patches, despite a relatively low intake rate of digestible organic matter in the short patches. Four hypotheses on foraging strategy were examined to explain the allocation of time or bites between patches: random allocation according to bites, random allocation according to grazing time, matching of time in proportion to digestibility, and matching of time in proportion to intake rate of digestible organic matter. The observed distribution of bites and time between patches was significantly different from the predictions of the various hypotheses. Patch choice was better explained by a random allocation of grazing time than by a random allocation of bites. Matching for digestible organic matter intake rate yielded the worst predictions of patch selection. Matching for digestibility gave the best explanation of patch selection, but the improvement compared to a random allocation of grazing time was not significant. The significance of the contribution of digestibility to selection may have been confounded by the effect of increased selectivity within tall patches. Observed patch selection was considered in relation to the maximization of energy intake rate. The selectivity of cattle was not pronounced, but it was consistent with a principle of maximization of energy intake on a daily basis instead of a short-term basis. Selectivity appeared to be constrained by costs of searching for and discriminating between different forage resources. It is concluded that a flexible selection for short patches over tall patches and avoidance of stemmy patches provides a good approximation of energy intake maximization in a complex and changing environment.     

Effect of dehulling of rapeseed on feed value and nutrient digestibility of rape products in pigs

In the presented study the influence of dehulling rapeseed on the composition of rapeseed meal (RM) and rapeseed cake (RC) and on its feed value for piglets and growing-finishing pigs was investigated. Before withdrawal of oil, rapeseed (variety Express) was dehulled applying a procedure developed by SKET GmbH Magdeburg and the Section Food-Technology of the University Essen. The steps of the dehulling procedure were described. For RM the oil was removed by the prepress-solvent procedure till a crude fat content of 2.1% in DM. RC was produced by pressing only resulting approximately 13% crude fat in DM. The RM and RC from not dehulled (ND) and dehulled (D) rapeseed were examined analytically. Crude nutrients, sugar and fibre substances, amino acids, some minerals and trace elements, fatty acids, glucosinolates and sinapine, and phytate were determined. By dehulling the seed the crude fibre content was decreased in RM and RC by approximately 40%. The ADF content declined by 35 and 39%, and the NDF content by 28% and 40% in RM and RC, respectively. The decrease in ADL content amounted to 50% and 65% for RM and RC, respectively. On the other hand, the CP content of RM and RC was increased by 7% and 13%, respectively, by dehulling the seed while the amino acid content of rape protein increased only slightly. The contents of glucosinolates and sinapine were also increased by dehulling, while the contents of phytate and phytate P were decreased. In digestibility and balance experiments with piglets and intact hybrid breeds of growing-finishing pigs, the digestibility of organic matter and of crude nutrients and the contents of digestible energy and metabolizable energy were estimated. Furthermore, the precaecal digestibility of crude nutrients and amino acids was determined with fistulated mini-pigs. By dehulling the seeds the digestibility of organic matter from RM and RC was improved in piglets and adult pigs by approximately 10%, and the ME contents increased by 13-15%. The precaecal digestibility of the sum of amino acids was increased by approximately 3 and 6 units in RM and RC, respectively. The precaecal digestibility of lysine in RM and RC reached that of soybean oil meal from not dehulled beans.     

The digestibility and nutritive value for dairy heifers of rations containing cellulose fibre

Cellulose residue (cellufiber) from an ammonium base acid sulphite paper process was accepted by dairy heifers to the extent of 40% of the dry matter of an all-roughage ration when mixed with maize (Zea mays) silage at time of feeding. No adverse physiological effects were observed during digestion trials lasting 80 days in which cattle were given successively diets containing 10, 20, 30 or 40% of the ration dry matter as cellufiber. Apparent digestibility of crude protein decreased and digestibility of crude fibre and acid detergent fibre increased as the cellufiber level in the ration increased. Digestibility coefficients of dry matter, nitrogen-free extract and gross energy were unaffected.Uniformity of values for total digestible nutrients, digestible energy and metabolizable energy and, also, of the body weight gains by the test animals indicated only small differences in nutritive value between rations. However, estimated nutritive values of ration components indicated appreciable differences. The TDN of cellufiber was 56% which was approximately equal to that of alfalfa (Medicago sativa) hay and was 82% of the value of maize silage. However, the digestible energy value of cellufiber (1.93 Mcal/kg DM) was only 77% of alfalfa hay and 69% of maize silage. Similarly, its metabolizable energe value of 1.41 Mcal/kg DM was 69% of that of alfalfa hay and 61% of that of maize silage.     

Changes in the digestibility of constituents of the diet in the rabbit]

Fiber digestibility of two diets (the first based on alfalfa dried, the second based on beet-pulp dried) with the same level of crude fiber and crude protein was measured on rabbits of 6, 7, 11, 13 and 17 weeks old. The age has no significative effect on digestibility (dry matter, organic matter, crude fiber) of the two experimental diets. The quantity of cellulose and hemicellulose digested was greater in rabbits on the pulp diet. Independantly of the diet hemicellulose is more digestible than cellulose. Expediency of use other analytical test than crude fiber in the nutritional requirements of rabbits is discussed.     

Proper energy evaluation of commercial laboratory animal diets based on digestibility and metabolizable energy values

The energy values of commercial laboratory animal diets have been customarily calculated by applying physiological fuel values (PFV) in this country. In order to ascertain accuracy of this application, apparent digestibility of crude protein, crude fat, nitrogen-free extracts (NFE), carbohydrate (NFE + crude fiber) and nitrogen-corrected metabolizable energy (MEn) of 10 commercial diets were determined using rats, dogs, rabbits and guinea pigs, respectively, and true digestibility of crude protein and crude fat of 12 feed ingredients was determined using rats. Apparent digestibility of the nutrients in the diets decreased with an increase in the crude fiber content of the diets. MEn values of the diets ranged between 2.18 and 3.75 kcal per g dry matter depending upon the crude fiber content of the diets. The energy values of the 10 diets calculated using PFV values of 4 kcal/g for protein and carbohydrate and 9 kcal/g for fat were compared with each MEn. The calculated values were 1.04 to 1.39 times higher than those of the respective MEn. All of the diets and most feed ingredients did not show high digestibility of nutrients assumed for the application of PFV. Therefore, it is concluded that application of PFV to the diets results in over-estimation of energy values and use of PFV for commercial laboratory diets in our country is not warranted. It is advisable to use MEn to evaluate energy value of commercial laboratory animal diets.     

Principles governing the use of chemical methods for assessing the nutritive value of forages: A review

The potentially digestible organic matter of forages is the sum of the apparently digested cell contents and the truly digested cell walls. These two fractions can accurately be predicted from a knowledge of the ash and cell wall content and an estimate of cell wall digestibility. A determination of cell wall content is valuable as an indicator of both the voluntary consumption of forages and the efficiency of utilization of metabolizable energy (ME) for growth and fattening. A separate estimate of the digested cell walls is essential as the basis for estimating the digestion of organic matter achieved in practice. The major outstanding problem in practice is still to find a rapid, universal and accurate method of assessing cell wall potential digestibility. The energy value of the digested organic matter can be calculated from a knowledge of the protein content of forages and ME from this estimate of digested energy. Attempts to predict ME from lignin or lignocellulose alone, while rapid and less costly, invariably have errors of at least ± 7% and recent research on the effect of environment on chemical composition suggests that if the existing relations are applied outside their local climatic zones, or in abnormal seasons, the errors may well be greater.     

Digestive efficiency of the Hoatzin, Opisthocomus hoazin: a folivorous bird with foregut fermentation

The Hoatzin Opisthocomus hoazin is the only known bird with a well-developed foregut plant fermentation system; most fermentation takes place in the crop and caudal oesophagus. To test Hoatzin digestive efficiency, balance (total collection) trials with captive Hoatzins were made using two experimental diets of different composition and fibre content. Dry matter (DM) intakes were similar for the diets (mean = 62.8 g DM/kg body mass/ day). Average DM, organic matter and nitrogen digestibilities were not significantly different between diets, with average values of 72.9%, 75.0% and 78.3%, respectively. In vitro organic matter digestibilities by cow ruminal inoculum were very similar to organic matter digestibilities in live Hoatzins for both diets. Fibre digestibility was among the highest recorded for herbivorous birds. Cellulose and acid detergent fibre digestibilities were 58.8% and 52.7%, respectively. Neutral detergent fibre (NDF) digestibility differed among diets—the higher the NDF content of the diet, the higher the NDF digestibility. The NDF digestibilities were 37.9% and 70.9% for the two diets with NDF concentrations of 32.4% and 37.3%, respectively. Differences in NDF digestibility can be attributed to the different concentrations of hemicellulose in the experimental diets. The high overall digestibility by captive Hoatzins is higher than values previously reported for other avian herbivores but similar to those of foregut-fermenting mammals on similar diets. The unique digestive strategy of the Hoatzin maximizes digestion of cell wall and cell contents. The high digestive efficiency in the Hoatzin is not predicted by allometric models of fibre digestion as a function of body mass. Other nutritional benefits, such as detoxification of plant secondary compounds and microbial synthesis of essential amino acids and vitamins, may explain the evolution of foregut fermentation in this avian folivore.     

Prediction of the in vivo digestibility of whole crop wheat from in vitro digestibility,chemical composition,in situ rumen degradability,in vitro gas production and near infrared reflectance spectroscopy

Twenty-six winter wheat forages (cultivars Slepjner, Hussar and Cadenza) harvested at three stages of maturity in each of two years, were conserved with or without Maxgrass additive or with urea (20 or 40 g kg⁻¹ dry matter; DM) in 200 l barrels. The forages were analysed for in vivo digestibility in wethers, chemical composition, in vitro rumen fluid-pepsin digestibility, in vitro neutral detergent-cellulase plus gamannase digestibility (NCGD), in vitro fermentation gas production and in situ rumen degradability. Forages were also scanned using near-infrared reflectance spectroscopy (NIRS) and calibration equations developed for predicting in vivo digestibility. In vivo digestible organic matter content (DOMD) was poorly predicted by cell wall content (r²≤0.19), NCGD (r²≤0.41), rumen fluid DOMD (r²≤0.41), rumen degradability (r²≤0.44) and in vitro gas production (r²≤0.26). Although crude protein content was a better predictor (r²≤0.48), the relationship differed (P<0.05) with the year of harvest of the forages. In contrast, NIRS was a more accurate and consistent predictor of DOMD in vivo (r²=0. 87). This study indicates that traditional laboratory-based feed evaluation techniques are unsuitable for predicting the DOMD of WCW, but that NIRS holds promise. However, as only 26 forages were used to derive the calibration equation, further research is required using large (150) data sets to validate the promise shown by NIRS and enable its adoption by the advisory services.     

Apparent digestibility of crude protein and gross energy in some plant and animal-based feedstuffs by Clarias isheriensis (Siluriformes: Clariidae) (Sydenham 1980)

Apparent digestibility coefficient (ACD) of dry matter, crude protein and gross energy of white fish meal, blood meal, poultry by-product meal, hydrolysed feather meal, shrimp head meal, meat and bone meal, soybean meal, cottonseed meal, peanut meal, yellow maize, corn starch, cassava meal, sorghum, rice bran and cocoa pod meal were determined for Clarias isheriensis (47.5–51.2 g) fed to satiation with diets containing each test feedstuff in a 30:70 mixture with a reference diet, and chromium oxide as an indicator using the dissection technique. ADC_protein values ranged from 50 to 93 % while ADC_energy ranged from 42 to 98 %. Protein and energy content of animal or plant feed-stuffs were equally digestible to C. isheriensis.     

Effects of inclusion with blue lupins (Lupinus angustifolius) in broiler diets and enzyme supplementation on production performance, digestibility and dietary AME content

An experiment with broiler chickens was conducted to study the effect of inclusion of blue lupins and exogenous enzyme to broiler diets on the apparent metabolisable energy (AME), digestibility and performance. Two basal diets were formulated: a non-lupin diet A based on soya bean meal and maize, and a diet B where parts of soya bean meal and maize were substituted with blue lupin (200 g/kg). The two basal diets were fed either alone or, for diet B in combination with different enzyme preparations (Bio-Feed Plus, lactase, two galactanases (Gal-I and Gal-II)). The experiment was performed in battery cages with 648 male broiler chickens, where eight experimental diets were fed to the chickens from 7 to 21 days of age and weight gain and feed intake were measured during the period. At the end of the experiment, three chickens from each pen were slaughtered and the content from jejunum and ileum was separately collected and pooled and used for measurement on intestinal viscosity. For measurements of the apparent metabolisable energy and the apparent digestibility, excreta were collected at 22–24 days of age and ileal contents collected at 25–26 days from the remaining chickens.

Substitution of soya bean meal and maize with blue lupin depressed weight gain (9%) and feed conversion ratio (12%) significantly. Feed intake of the lupin-based diets was not decreased. The protein in lupin was digested to the same extent as the protein from soya bean meal, the coefficient of ileal apparent digestibility being on average 0.75. However, the high content of the non-starch polysaccharides (NSP; 450 g/kg) in lupin depressed the apparent digestibility of the organic matter by approximately 10%. The AME_n of the non-lupin diet was 14.01 MJ/kg dry matter (DM) compared to a value of 13.11 MJ/kg DM in the lupin control diet. Improvements in the measured parameters were seen with some of the enzymes. Gal-I, and Gal-II in combination with lactase were the most efficient enzymes concerning improvement in AME_n and performance. Weight gain was increased by 3.5–5.5% by addition with these enzymes. Gal-I increased the AME_n significantly to 13.65 MJ/kg, a value not significantly different from the AME_n of the non-lupin diet. There was no effect of addition with the different enzymes on the coefficients of apparent digestibility of organic matter measured in the ileum, whereas addition with Gal-I to the lupin diet increased the apparent digestibility of organic matter over the total tract by 3%. The mode of action of the galactanases has been to hydrolyse the galactan in the NSP cell wall of lupins to galactose and dimers of galactose, which are energy-yielding to poultry. From the results obtained, it can be indicated that Gal-I increased the energy utilisation of the lupin-based diet, confirmed by the improved AME_n content and performance.     

Dairy cow nutrition in organic farming systems. Comparison with the conventional system

The energy supplied by the high-forage diets used in organic farming may be insufficient to meet the requirements of dairy cattle. However, few studies have considered this problem. The present study aimed to analyze the composition of the diets and the nutritional status (focusing on the energy–protein balance of the diets) of dairy cattle reared on organic farms in northern Spain, which are similar to other organic farming systems in temperate regions. Exhaustive information about diets was obtained from organic (ORG) and representative conventional grazing (GRZ) and conventional no-grazing (CNG) farms. Samples of feed from the respective farms were analyzed to determine the composition. Overall, the diets used on the ORG farms were very different from those used on the CNG farms, although the difference was not as evident for GRZ. The CNG farms were characterized by a higher total dry matter intake with a high proportion of concentrate feed, maize silage and forage silage. By contrast, on ORG and GRZ farms, the forage, pasture and fibre intake were the most important variables. The ration used on ORG farms contained a significantly higher percentage of ADF and lower organic matter (OM) content than the rations used in both of the conventional farming systems, indicating that the diets in the former were less digestible. Although the protein concentration in the diets used on the grazing farms (ORG and GRZ) was higher than those used on CNG farms, the protein intake was similar. The results indicated an imbalance between energy and protein due to the low level of energy provided by the ORG diets, suggesting that more microbial protein could be synthesized from the available rumen-degraded dietary nitrogen if rumen-fermentable OM was not limiting. The imbalance between energy and protein led to a reduced amount of total digestible protein reaching the intestine and a lower milk yield per kilogram of CP intake on the ORG farms. In order to improve the protein use efficiency and consequently to reduce the loss of nitrogen to the environment, organic farming should aim to increase the energy content of cattle diets by improving forage quality and formulating rations with more balanced combinations of forage and grain.