The feeding value of ammoniated flax straw,wheat straw and wheat chaff for beef cattle

Two experiments were conducted to assess the feeding value of ammoniated and untreated flax straw, wheat straw and wheat chaff in comparison to a mixed bromegrass/alfalfa hay. Anhydrous ammonia was applied to the crop residues at the rate of 35 kg t⁻¹ dry matter. In the first experiment, the effect of ammoniation on crude protein, acid detergent fibre (ADF), neutral detergent fibre (NDF) and acid detergent lignin (ADL), digestible organic matter in vitro and in vivo (DOM%), ADF and NDF digestibility of the crop residues was determined. In the second experiment, ammoniated flax straw, ammoniated wheat straw, ammoniated and untreated wheat chaff, each supplemented with barley, were compared to bromegrass/alfalfa hay as feed sources for wintering beef cows.Ammoniation increased the crude protein content of the crop residues ∼2-fold. Wheat straw DOM in vitro and in vivo was not increased by ammoniation. Ammoniation increased the DOM in vitro of wheat chaff from 36.3 to 46% and flax straw from 35.2 to 46.3%. The DOM in vivo increased from 53.3 to 63.4% (P < 0.05) for wheat chaff and from 33.9 to 58.4% (P < 0.05) for flax straw following ammoniation. Digestibility of ADF increased from 9.9 to 43.9% (P < 0.05) and of NDF from −0.6 to 37.9% (P < 0.05) in flax straw with ammoniation. Non-significant increases in ADF and NDF digestibility were observed for all other crop residues. Lignin content was not changed in the crop residues by ammoniation.In the winter feeding trial, young cows gained more weight than older cows (P < 0.05). Average daily gains of cows were greatest for hay followed by ammoniated flax straw, ammoniated chaff, untreated chaff and ammoniated wheat straw rations (P < 0.05). Increases in backfat in the younger cows was greatest with hay and ammoniated flax straw, followed by ammoniated chaff and ammoniated wheat straw (P < 0.05). Untreated chaff caused no increase in backfat thickness.Ammoniated flax straw (3.2 kg day⁻¹) given with barley (5.6 kg day⁻¹), is similar in feeding value to medium quality bromegrass/alfalfa hay. Furthermore, wheat chaff and ammoniated wheat chaff show good potential as alternatives to hay in winter feeding.     

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.     

The effects of cereal particle size and pelleting on the nutritive value of oat-based diets for the growing pig

Oat grains from a single source were ground in a hammer mill, either with no screen present (coarse) or through 1.56 or 4.68-mm screens, to produce three samples with different particle size distributions. At inclusion levels of 850 g kg^?1 the three samples were used as the bases of three otherwise identical diets. Half of each diet was steam pelleted to give pellets of 7-mm diameter and the other half retained as a meal form. Factorially designed metabolism experiments using 30 pigs of 20 kg initial live weight and a growth experiment using 72 individually fed pigs of 25 kg initial live weight were made.Pelleting or particle size of the diet had no significant effect on (a) apparent digestibility of dry matter (DM), modified acid detergent fibre and gross energy (b) digestible (DE) and metabolisable energy (ME) contents (the DE contents of the meal and pelleted diets were 12.81 and 13.03 MJ kg^?1 DM, respectively) and (c) nitrogen retention. Apparent digestibility of the ether-extractable fraction was significantly poorer in meals (cf. pellets) and in the diets based on coarse grains compared with those based on the two finer-ground samples. Also, apparent digestibility of nitrogen was significantly poorer in the diets based on the coarse grains (0.803) compared with that based on the 1.56-mm ground grain (0.832). Growth and efficiency of feed conversion were significantly improved by pelleting the coarse grain diet, and the meal diet based on the coarse grain gave significantly inferior results compared with those from the two other meal diets.     

Methods of improving the utilization of cereal straw by ruminants. II. Further studies on dried grass as a supplement for lambs

Sixteen growing castrated lambs (37.0 ± 3.31 kg) were used in two 5 × 5 and one 6 × 6 Latin squares to measure the intake and digestibility of: (1) urea—molasses-treated straw, or mixtures containing (2) 25; (3) 50; or (4) 75% dried grass; and (5) grass alone. The dry matter intake was 40, 50, 69, 84 and 90 g day^?1 per kg of metabolic live weight (P<0.001), and digestibility was 470, 489, 591, 671 and 735 g kg^?1, respectively, for the above treatments. The dry matter intake of lambs offered diets 2, 3 and 4 as complete diets was 47, 56 and 66 g day^?1 kg of metabolic live weight, and digestibility was 513, 621 and 673 g kg^?1, respectively. When the feeds were offered separately, dry matter intake was 54, 63 and 78 g day^?1 per kg of metabolic live weight and digestibility was 541, 582 and 662 g kg^?1, respectively. Dry matter intake for mixed diets was higher (P<0.01) than for feeds given separately.     

Effects of treatment of barley straw with anhydrous ammonia and supplementation with heat-treated protein meals on feed intake and liveweight performance of growing lambs

Two feeding experiments were conducted in which lambs were given a basal diet of barley straw, supplemented with urea and minerals. The aim of the experiments was to increase lamb performance by (i) supplementation of the diet with protein meals that were largely undegraded in the rumen, (ii) treating the barley straw with anhydrous ammonia to increase its digestibility, or (iii) a combination of both.In Experiment 1, lambs were given the basal diet supplemented with 0, 60, 120, 180, 240, 300 or 360 g heat-treated protein-meal/kg straw. At the 300 g/kg level of supplementation, the protein pellet increased liveweight gain by 82 g/day, intake of barley straw by 110 g/day, and wool growth by 3.3 g/day, in comparison with unsupplemented lambs.In Experiment 2, untreated barley-straw or barley straw treated with anhydrous ammonia (4% w/w) was given to growing lambs. Each diet was supplemented (g/kg straw diet) with 100, 200 or 300 of two heat-treated protein-meals. Ammoniation of the barley straw increased dry matter (DM) digestibility in vitro from 49 to 57%, and hemicellulose content was reduced by 20%. Total N content of the straw was increased from 4.6 to 9.8 gN/kg DM by ammoniation, 65% of the increased N being potentially degradable in the rumen. As a result of ammoniation, digestible dry-matter intake of lambs was increased by 60 g DM/day and liveweight gain increased by 15 g/day.There was no significant difference between the two protein supplements with respect to either total feed intake or liveweight gain. Liveweight gain was significantly increased by both supplements (71, 106 and 125 g/day for each level of supplementation, respectively), but neither supplement had a significant effect on the intake of barley straw.Supplementation of a low-protein, low digestible diet of barley straw with a pelleted protein-meal considerably increased liveweight gain of growing lambs and maintained straw intake. By comparison, treatment of barley straw with anhydrous ammonia increased its digestibility, but had only a minor effect on lamb performance.     

Food Sorting by Collared Lemmings (Dicrostonyx groenlandicus) and Prairie Voles (Microtus ochrogaster): A Cautionary Note for Digestibility Studies

Small herbivores are often confronted with poor quality diets; in response to this situation, they may sort their food to increase diet quality. Neutral detergent fiber (NDF) levels were measured in three pelleted diets fed to collared lemmings (Dicrostonyx groenlandicus) and prairie voles (Microtus ochrogaster) and compared to levels in orts collected from the same diets and animals. Lemmings sorted and discarded the fibrous parts of food pellets on all three diets (17.3% to 25.9% higher NDF in orts), whereas voles sorted out fibrous particles on only one diet. Calculations of NDF digestibility were significantly reduced by particle sorting (up to 16.9% decrease in digestibility). In reviewing the literature, we found that in more than half of studies examined, orts may not have been analyzed for these differences. Researchers must carefully consider such effects, especially when conducting digestibility studies with herbivores on pelleted diets.     

The feeding value for ruminants of straw and wholecrop barley and oats treated with anhydrous or aqueous ammonia or urea

Ammonia-treated or untreated barley straw supplemented with urea was given as the only feed to two groups of Friesian heifers weighing approximately 550 kg. The digestibility of dry matter (DM) was 58.8 and 49.9%, daily feed intake was 5.88 and 3.87 kg and daily liveweight change was +324 and -447 g for the ammonia-treated and control barley straw diets, respectively.Anhydrous or aqueous ammonia (NH₃) was injected into large round straw bales covered with plastic. The rates of degradation of barley straw in nylon bags and digestibility in vivo were the same for both ammonia treatments. The distribution of N in the bales was also similar and uniform with both treatments. No differences were recorded in the rate of degradation in nylon bags if the plastic was removed 2 or 8 weeks after treatment.Anhydrous or aqueous ammonia or isonitrogenous amounts of urea were injected into large round bags containing whole-crop barley or oats collected with a forage harvester. The digestibility of starch by steers was about 92% for ammonia-treated samples and 78% for the urea-treated samples. Urea and ammonia efficiently preserved the whole-crop materials but untreated control samples and samples treated with NaOH deteriorated during storage.     

Effect of high-pressure steam treatment on chemical composition and digestibility in vitro of roughages

Effect of high-pressure steam (5, 7 and 9 kg cm^?2 for 30 and 60 min) on chemical composition and digestibility in vitro of sugarcane bagasse, paddy straw and sorghum straw was studied. The treatment brought about significant falls in the neutral detergent fibre (NDF), specifically the hemicellulose content, and in pH. Soluble carbohydrates and volatile acids (VA) increased with treatment, while acid detergent fibre (ADF) remained constant. The increments in true dry-matter digestibility in vitro (IVTDMD) compared to untreated were 23–64% (sugarcane bagasse), 19–36% (paddy straw) and 31–42% (sorghum straw) with increasing steam pressures and period. The digestibility of cell-wall constituents (CWC) improved with steam treatment in all three roughages. The dry-matter losses resulting from the treatment were 0.9–20%, 17–39% and 1–22% for sugarcane bagasse, paddy straw and sorghum straw, respectively.     

The effect of ammoniation on the intake and nutritive value of straw

Studies were conducted to compare the increases in dry matter digestibility (DMD) in vitro and in vivo and to determine the metabolisable energy (ME) value of straw ammoniated at ambient temperature. Two stacks of straw sealed with polyethylene were allowed to react with 3% (w/w) anhydrous NH₃ for 30 and 56 days, respectively. Both DMD in vitro and nitrogen tests were carried out over an eight-week period subsequent to opening the stacks. Digestibility in vivo was measured with 12 wether lambs. The non-treated and ammoniated straws were given ad libitum, with a supplement of either ground barley or a lamb concentrate which contained 16% crude protein (CP).There was a mean increase of 15 percentage units in DMD in vitro for the ammoniated straw irrespective of whether it was treated for 30 or 56 days. The corresponding increase in mean DMD in vivo was 14.2 units. The CP content of the straw was increased from 3.1 to 7.6%. The increase in DMD in vitro and total N content was maintained throughout the sampling period. Approximately 58% of the anhydrous NH₃ added to the straw appeared to have been irreversibly “bound” to the straw. The ME values for the ammoniated straw were 6.78 and 7.49 MJ/kg when the straw was supplemented with either barley or the lamb concentrate, respectively. Straw ammoniation had a marked effect on intake. The overall increase in intake was 70% for the treated compared with the non-treated material.     

Does the effect of pelleting depend on the wheat sample when fed to chickens?

Experimental comparisons of the nutritional value of different wheat cultivars commonly use feeds in meal form even though the large-scale broiler producers use steam pelleted feeds. The aim of this experiment was to examine the effect of steam pelleting on the performance, dietary N-corrected apparent metabolisable energy (AMEn), total tract dry matter retention (DMR), nitrogen retention (NR) and fat digestibility (FD) coefficients, and digestive tract development of broilers fed four different wheat samples in complete diets. Four European wheat samples, with different chemical composition and endosperm characteristics, were used in a broiler experiment. The wheat samples were milled through a 5 mm screen and four basal feeds containing 670 g/kg of each selected wheat sample were mixed. The basal feeds were then split into two batches and one of them was steam pelleted resulting in eight experimental diets. Each diet was fed ad libitum to eight pens of two male Ross 308 broilers from 10 to 24 days of age. Feeding pelleted diets improved (P<0.001) feed intake and weight gain, and daily water intake of the birds. Pelleting also improved dietary AMEn and FD (P<0.001) and DMR (P<0.05). An interaction (P<0.05) was observed between wheat samples and steam pelleting for NR. Steam pelleting improved (P<0.05) NR in the wheat sample with high starch and protein and hard endosperm but not in the rest of the wheat samples. Similar interactions (P<0.05) were also observed between wheat sample and steam pelleting for gain to feed (G : F) and water to feed (W : F) ratios. Pelleting improved G : F ratio the greatest in the wheat sample with high starch and protein and hard endosperm. Feeding the same wheat sample also decreased (P<0.05) W : F but only in the mash diets. Regardless of the wheat sample the values of dietary AMEn did not differ (P>0.05). Feeding different wheat types and pelleting did not (P>0.05) change the development of the gastrointestinal tract of the birds. The study showed that there were differences between four wheat samples when they were fed in pelleted complete feed, but no differences were observed when fed in mash form complete diets. Research on the interaction between pelleting and wheat chemical and quality characteristics is warranted.     

Influence of steam pelleting on the feeding value of Tower and Candle rapeseed products for broiler chickens

Male broiler chickens were offered diets containing up to 30% Tower rapeseed meal, with these diets being prepared in mash or steam pelleted (crumble) form. In 4 experiments, birds receiving a maize and soya bean meal control diet showed a significant improvement in weight gain when crumbles, rather than mash diets, were used. With isocaloric, isonitrogenous diets containing rapeseed meal, no such improvement in growth rate was observed. Steam pelleting exerted no consistent effect on feed conversion. There was no significant difference in the growth rate of birds receiving mash diets irrespective of composition, while for crumbled diets, birds consuming the maize and soya bean control diet were heavier than comparable rapeseed-fed birds, with this difference being significant in 2 experiments. By adding fat, necessary to maintain rapeseed diets isocaloric, after the pelleting process, it was shown that fat per se was not responsible for failure to elicit a growth response with pelleted rapeseed meal diets. The response to pelleting was similar with diets prepared in an experimental pelleting machine at the university or by a commercial feed mill. Reduction in amino acid availability, in particular of arginine, is tentatively discussed in relation to the non-improved growth rate observed with pelleted diets containing rapeseed meal. Improvement in growth rate with pelleted vs. mash diets containing whole, raw rapeseeds is interpreted as a response to the heat treatment involved with the pelleting process.     

Effects of diets differing in protein source and technical treatment on digestibility,performance and visceral and biochemical parameters of fattening pigs

The aim of the experiment on 100 cross-bred barrows was to compare commercial diets for fattening pigs based on either soya bean meal (SBM) imported from non-European countries with diets based on a mixture of locally produced rape seed meal, distillers’ dried grains with solubles and soya beans as main protein sources. In addition, these both types of diets were processed by two different technical feed treatments, i.e. coarse grinding without hydrothermal treatment or fine grinding and pelleting. With only few exceptions, nutrients of the diet without SBM were more digestible (p < 0.05) resulting in a higher metabolisable energy (ME) content. Fine grinding and pelleting increased also the ME content and the nutrient digestibility with the exception of crude fibre. Higher feed intake of animals that fed diets without SBM (p < 0.01) resulted in higher average daily gain (p < 0.01). However feeding this diet, the higher digestibility was not reflected in a decreased feed-to-gain ratio (FGR), but fine grinding and pelleting reduced FGR (p < 0.001). A higher pH value and a lower DM content of caecal chymus were detected in animals that received coarsely ground feed (p < 0.05). Animals that fed finely ground and pelleted feed had higher slaughter and relative liver weights and higher blood cholesterol concentrations (p = 0.040). The urea concentrations of blood were lower (p = 0.019) after feeding diets without SBM. In conclusion, SBM imported from non-European countries can be replaced by alternative local protein sources without compromising digestibility or performances of animals. Although fine grinding and thermal treatment particularly seemed to be advantageous for digestibility and performance, the possible risk of development of stomach lesions should be considered.     

Effects of particle size and hydro-thermal treatment of feed on performance and stomach health in fattening pigs

Effects of grinding and hydro-thermal treatment of feed on growth performance, slaughter traits, nutrient digestibility, stomach content and stomach health were examined by using 96 crossbred fattening pigs. Pigs were fed a grain-soybean meal-based diet processed by various technical treatments. Feeding groups differed in particle size after grinding (finely vs. coarsely ground feed) and hydro-thermal treatment (without hydro-thermal treatment, pelleting, expanding, expanding and pelleting). Fine grinding and hydro-thermal treatment showed significant improvements on the digestibility of crude nutrients and content of metabolisable energy. Hydro-thermal treatment influenced average daily gain (ADG) and average daily feed intake (DFI) significantly. Finely ground pelleted feed without expanding enhanced performances by increasing ADG and decreasing feed-to-gain ratio (FGR) of fattening pigs. Coarsely ground feed without hydro-thermal treatment resulted in the highest ADG and DFI, however also in the highest FGR. Expanded feed decreased DFI and ADG. Slaughter traits were not affected by treatments. Coarsely ground feed without hydro-thermal treatment had protective effects on the health of gastric pars nonglandularis, however, pelleting increased gastric lesions. Hydro-thermal treatment, especially expanding, resulted in clumping of stomach content which possibly induced satiety by slower ingesta passage rate and thus decreased feed intake. Pigs fed pelleted feed showed less pronounced development of clumps in stomach content compared with expanded feed.     

The influence of steam pelleting and grinding on the nutritive value of Canola rapeseed for poultry

In an attempt to explain the poorer performance and lower fat digestibility often encountered with Canola seed diets, maize and soya bean diets containing 20% Canola seed or an equivalent amount of added fat (8%) from maize oil, Canola oil, tallow or an animal—vegetable blend fat, were given to broiler chicks. Although significant differences in $\text{feed}\text{gain}$ ratios and fat digestibility were noticed, all diets promoted good growth, and dietary fat appeared to be well utilized.In a second experiment, to reinvestigate the effects of mash vs. pelleted diets, marked improvements were noted in performance, and especially in the digestibility of the fat from Canola seed diets, in response to steam pelleting. Examination of the mash diet revealed approximately 6% whole Canola seeds and other seeds at various degrees of pulverization.A third experiment compared Canola seed passed once or twice through a hammer mill, either by itself or mixed 50:50 (w/w) with maize, before being mixed with other dietary ingredients. Again, whole seeds were noted in the ground material. The Canola seed mixed with maize and ground once had 26% whole seeds, while the seed ground twice by itself had no whole seeds but many that were little better than cracked. All diets were given as mash or as steam crumbles. Marked improvements in weight gain and $\text{feed}\text{gain}$ ratios and fat digestibility were noted for the crumbled vs. the mash diets. It is obvious that some of the variable results reported for Canola seed can be related to fineness of grind of the material. The steam pelleting process results in sufficient pulverization, or breaking up of the seed, to allow for optimum performance with diets containing up to 20% Canola seed. Heating per se might also be an important consideration in steam pelleting. One can conclude that up to 20% Canola seed can be used in steam-pelleted diets based on maize and soya bean meal without altering broiler performance.     

Performance,gut morphology and carcass characteristics of fattening rabbits as affected by particle size of pelleted diets

A review of past literature revealed inconsistencies in recommended feed particle size for optimal growth and productive performance of rabbits. Changing diet formulation and subsequent processing conditions may improve pellet texture and potentially affect rabbit performance. In the current study, two isoenergetic and isonitrogenous pelleted diets were formulated, which varied in the particle size of the concentrates (2 and 8 mm, respectively). The objective was to evaluate the effect of different particle sizes of compound diets on performance, nutrient utilisation, gut morphology, and carcass characteristics of fattening Italian White breed rabbits. The finely ground diet led to a significant improvement in feed efficiency and apparent digestibility of crude protein, ether extract, crude fibre and NDF, without any negative effect on gut morphology. Furthermore, a smaller particle size of concentrates in pelleted diets improved carcass traits. Meat colour parameters showed significant differences in longissimus lumborum and biceps femoris due to dietary treatments, but in both muscles pH values 1 h and 24 h after slaughter remained unchanged. It is concluded that a finely ground pelleted diet can be used to improve growth performance of rabbits without affecting carcass parameters.     

Digestion of organic matter and nitrogen in ammoniated barley straw

Barley straw, either treated with anhydrous ammonia (40 g/kg for 28 days) or untreated, was chaffed and given to sheep in an intake and digestibility trial, or was ground and incubated in nylon bags in the rumen of sheep fed on lucerne or untreated or ammoniated straw.Ammoniation increased the N content from 2.45 to 10.63 g/kg dry matter (DM). Of the increment, 67% was retained in water-soluble form and 11.5% was in the cell wall organic matter (CWOM). The water-soluble N appeared to be retained by sheep as well as urea-N given with untreated straw; digestibility coefficients obtained in vivo, and by nylon bag incubation, suggested that N in CWOM was largely unavailable.Ammonia treatment increased the potential digestibility (measured by nylon bag incubation) of DM and CWOM by 23 and 29%, respectively. Digestibility in vivo of OM increased from 0.42 to 0.60 and of CWOM from 0.48 to 0.67. Intake of ammoniated straw increased over the 23-day feeding period, while that of untreated straw given with or without urea was constant or declined.     

Ammonia-treated barley straw and rolled barley offered either together, in a mixed ration, or successively to beef steers

Barley straw treated with anhydrous ammonia at a rate of 40 g per kg of straw dry matter (DM) and rolled barley were offered to 20 steers weighing initially 350 kg. Each steer was offered in total approximately 600 kg of straw DM and approximately 525 kg of barley DM. Ten steers were offered the straw alone in the long form at the beginning of the trial followed by the rolled barley alone. The remaining 10 steers were offered straw which had been ground through a 40-mm screen and mixed with the rolled barley in a complete diet. Dry matter digestibility coefficients of the ammonia-treated straw and the mixed straw plus barley diet were 0.52 and 0.57 ± 0.026, respectively. The DM digestibility coefficient of rolled grain in the mixed diet was predicted from the digestibility of starch to be 0.78 and the DM digestibility of straw in the mixed diet, determined by difference, was 0.39. Although steers offered the straw followed by rolled barley took on average 39 days longer to consume their total food allowance, cold dressed carcass weights of the two groups were not significantly different nor was there any difference in the carcass composition of the two groups of steers as determined by specific gravity measurements. Maintenance energy requirements were calculated for the two groups of steers and although the same amount of food was consumed by both groups and the energy required for maintenance was higher in the group offered straw followed by barley, the depression in the energy available from straw offered in a mixed diet caused the same total amount of metabolizable energy to be available for carcass gain to both groups.     

Utilization of alkali-treated grain. 2. Utilization by steers of diets based on hay or straw and mixed with either NaOH-treated or rolled barley

In the first of three experiments, Hereford cross steers were fed ad libitum from 325 kg to slaughter at 425 kg on diets containing 50% hay and 50% rolled or NaOH-treated (30 g/kg) barley. Liveweight gain and food conversion ratios were similar for the two groups (1.24 vs. 1.42 kg/day; 7.0 vs. 7.0 kg dry matter intake/kg gain, respectively). Dry matter and organic matter digestibility was significantly higher (P < 0.01) when the diet contained rolled, rather than NaOH-treated, barley. There were no significant differences in fibre digestibility (51.2 vs. 59.1%, respectively).In the second experiment, the optimum level of NaOH was determined for the treatment of barley when given with hay. The level of NaOH required to achieve a digestibility in whole barley similar to rolled barley was 40 g NaOH/kg, i.e., approximately 10 g/kg more than when NaOH-treated barley formed the sole component of the diet. Dry matter and organic matter digestibility increased linearly as the level of NaOH applied increased (P < 0.05) and tended to peak at 40 g NaOH/kg barley. Starch digestibility also increased linearly (P < 0.001). Fibre digestibility did not vary significantly between treatments.In the third experiment, the voluntary intake of straw by steers given rolled or NaOH-treated barley at two levels of supplementation was determined. The intake of straw was slightly, but not significantly, greater when NaOH-treated rather than rolled barley was used. The digestibility of dry matter, organic matter, starch and fibre was not significantly affected by method of cereal treatment. No problems of animal health arose throughout the three experiments.     

Intake and digestibility in sheep fed on alkali-treated straw and concentrates,as complete diets or separate feeds

Twelve mature wethers were used in an experiment of change-over design to determine the effect of complete diet feeding on intake and digestibility of diets based on alkalitreated straw and a concentrate containing rolled barley and extracted soya bean meal. Two diets were used: D₁ with a 50:50, and D₂ with a 75:25 ratio of straw:concentrates on a dry matter basis. The straw and concentrates of each diet were given either separately (S) or as a complete diet (C). Complete diets gave a slightly, but not significantly higher intake (C, 86.5) and S, 82.5 g dry matter /kg W^0.75 per day). The separate method gave a significantly higher digestibility coefficient for dry matter (C, 62.2 and S, 65.5; P < 0.05) and for crude fibre (C, 57.2 and S, 62.5; P < 0.01). Water intake increased by 42.7 ml g^?1 Na derived from NaOH. There were no significant interactions between the method of feeding and the type of diet in intake and digestibility of the diets or in the intake of water.     

Impact of fibre intake and fibre source on digestibility,gut development,retention time and growth performance of indigenous and exotic pigs

The impact of fibre level and fibre source on digestibility, gastrointestinal tract (GIT) development, total tract mean retention time (MRT) and growth performance was studied in indigenous Mong Cai (MC) and exotic Landrace × Yorkshire (LY) pigs. The diets were based on maize, rice bran, soyabean meal, fish meal and soyabean oil, and cassava residue (CR) or brewer's grain (BG) as fibrous ingredient sources in the high-fibre diets (HF) and were fed ad libitum. A low-fibre diet (LF), containing around 200 g NDF/kg dry matter (DM), was formulated without CR and BG as feed ingredients. The HF diets (HF-CR and HF-BG) were formulated to contain around 270 g NDF/kg DM. The experiment was arranged as a 2 × 3 factorial completely randomized design with six replications, and lasted 27 days. Increased dietary fibre level resulted in a reduction (P < 0.05) in average daily gain, digestibility of organic matter (OM), CP and gross energy (GE) at the ileum and in the total tract, and in MRT, and an increase (P < 0.05) in the feed conversion ratio and in the weight of the GIT (except for small intestine and caecum). The coefficients of total tract digestibility of fibre fractions were higher in HF diets than in the LF diet, with highest values for diet HF-CR, which had a high proportion of soluble non-starch polysaccharides. MC pigs had longer MRT of digesta than LY pigs (P < 0.05), resulting in higher digestibility at the ileum and in the total tract. Across diets and breeds, the total tract apparent digestibility of OM, CP and GE was positively related (R² = 0.80 to 0.84) to the MRT of solids, whereas the MRT was negatively related to the DM intake (R² = 0.60).