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.     

The dye absorption test as an indicator of the nutritive quality of heat-processed navy bean

Under standardized conditions, the absorption of cresol red dye by navy bean meal increased from approximately 2.0 mg g^?1 for raw samples up to 3.8 mg g^?1 for optimally cooked samples. Within this range, a pooled correlation coefficient of 0.93 was obtained between dye binding value and $\text{gain}\text{feed}$ ratio of rats fed on diets comprising, in total, 51 differently processed navy bean meals in five bio-assay experiments. Over-heating of navy bean, as judged by a deterioration in the $\text{gain}\text{feed}$ ratio of rats, caused no further change in dye binding value until samples charred, whereupon dye binding values of the order of 1.5 mg g^?1 were observed. The practicality of the test for indicating the nutritive quality of heat-processed navy bean is discussed in the light of these findings.     

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.     

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.     

Pelleting and extrusion can ameliorate negative effects of toasting of rapeseed meal on protein digestibility in growing pigs

Toasting time (TT) of rapeseed meal (RSM), the diet processing (DP) method and the interaction between both on the apparent CP digestion along the gastrointestinal tract and the apparent ileal digestibility (AID) of amino acids of growing pigs were investigated. The experiment consisted of a 3×3 factorial design of TT of RSM (0, 60 and 120 min) and DP method (mash, pelleting and extrusion). In total, 81 boars with a starting BW of 20 kg were euthanized 4 h after their last feeding. The gastrointestinal tract was dissected and the small intestine divided in three sections of similar length. Samples were collected from the stomach, 1.5 m from the ends of each of the three sections of the small intestine, and the rectum. The apparent digestibility (AD) of CP for each of the small intestine sections was used to calculate the rate of CP digestion. Increasing the TT of RSM resulted in lower protein solubility, lower lysine/reactive lysine contents and higher protein denaturation, indicative of the occurrence of protein aggregation and Maillard reactions. There were significant effects (P⩽0.01) of TT on the AD of CP in the different sections of the gastrointestinal tract. The rate of CP digestion of the 0 min toasted RSM diets was 23% and 35% higher than that of the 60 and 120 min toasted RSM diets, respectively. There was a significant interaction (P=0.04) between TT and DP for the AID of CP. Although pelleting of the 0 and 60 min toasted RSM diets did not change the AID of CP with respect to the mash diets, pelleting of the 120 min toasted RSM diet increased the AID of CP by 9.3% units. Extrusion increased the AID of CP of the 0 and 60 min toasted RSM diets by 3.4% and 4.3% units with respect to the mash diets, whereas extrusion of the 120 min toasted RSM diet increased the AID of CP by 6.9% units. Similar positive effects of pelleting and extrusion were obtained for the AID of lysine and reactive lysine, especially in the diets with higher TT. In conclusion, processing (pelleting and extrusion) of RSM containing diets can ameliorate the negative effects of RSM toasting on protein and amino acid digestibility; these effects were larger for the RSM toasted for longer times.     

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.     

Feeding value of alkali-treated whole rye (secale cereale L.) grain for lactating cows and its digestibility for sheep

Alkali-treated whole rye grain (35 g NaOH/kg grain) and rolled rye grain were given to cows in diets with $\text{concentrate}\text{roughage}$ ($\text{C}\text{R}$) ratios of 65:35 and 75:25. Alkali treatment tended to increase intake (by 13% for the 65:35 diet), but non-significantly. Milk yield and composition did not differ significantly among the four treatments.Alkali treatment of rye tended to increase the molar proportion of acetic acid and decrease that of propionic acid, although non-significantly.Apparent digestibility of dry matter, crude protein and energy, determined by the acid-insoluble ash (AIA) technique, did not differ significantly among treatments.In another trial, alkali treatment of rye grain for sheep resulted in no significant improvement in dry matter, energy or cellulose digestion, but alkali treatment of barley increased the digestibility of acid detergent fibre and cellulose. The present studies show a slight tendency for improvement with alkali treatment of whole rye grain, but further investigations are needed.     

Review article: The alkali treatment of straws

The Beckmann method of alkali treatment consists of soaking straw in dilute alkali solutions for 24 hours and then washing it with clean water. Straw digestibility is increased from about 40 to about 70%. While this process has been known for 50 years, it has not been much used because treatment costs are too high. Also, it cannot be industrialised. The spray process, in which the straw is wetted with an alkali solution (Wilson and Pigden, 1964) is an improvement from both points of view, but poses nutritional problems since straw is not washed after treatment. So great is the potential, however, that within the last seven years nearly 100 research reports have been published on the production and use of spray-treated straw. These reports are reviewed in this article.Straws are poorly digested by ruminants because of their high cell-wall content. Alkali treatment disrupts the cell-wall by dissolving hemicellulose, lignin and silica, by hydrolysing uronic and acetic acid esters and by swelling cellulose. Digestibility in vitro increases from about 40 to about 80% with $\text{10}\text{g NaOH}\text{100}\text{g straw}$. Equally large increases are not, however, obtained in vivo because of unreacted alkali and/or high sodium concentration. Several hypotheses concerning the depression of digestibility in vivo are reviewed. In general $\text{3–6}\text{g NaOH}\text{100}\text{g straw}$ is the optimum. For maximum effectiveness the volume of the alkali solution must be between 50 and $\text{200}\text{ml}\text{100}\text{g straw}$. The usefulness of neutralising unreacted alkali has not yet been determined. Crop and industrial residues with lower initial digestibility than straw (e.g. paddy hulls, bagasse and some types of sawdust) are usually still too poor after treatment (digestibility 30–50%) to be useful feeds. Pressure and temperature increase the effectiveness of alkali, but add to the cost of treatment. The pelleting of treated straws probably increases the effectiveness of alkali treatment. The length of time treated straw is allowed to “cure” before being fed does not affect its digestibility. Chemicals other than NaOH, like chlorine, ammonia and peroxides, are also effective in treating straws but are more expensive and/or more difficult to apply.Animal feeding experiments with sprayed straw have shown its utility for livestock normally fed poor straw diets, in high concentrate diets for growing, finishing and milking stock, and as an extender of silage. The factors affecting the degree of improvement to be expected in digestibility, growth and production from the treatment of straw need to be identified and studied.In spite of its high pH and Na content, sprayed straw has not been found to cause any health problems in livestock when treatment is in the range of 3–8 g NaOH/100 g straw. The extra sodium is excreted in the urine. Water intake and urine volume increase. Milk composition is unaffected.Several factories producing alkali spray-treated straw-based diets in pelleted form are already in operation in Europe. The process is briefly described.     

Use of unextracted sunflower seeds as a protein source

Substitution of unextracted sunflower seeds for either 0, 25, 50 or 100% of the soya bean meal in pig diets produced no significant differences in digestible energy or apparent nitrogen retention. However, all diets containing unextracted sunflower seeds had significantly higher digestible nitrogen than the diets containing soya bean meal as the protein source. Replacement of 25% of the soya bean meal with unextracted sunflower seeds produced the greatest increase in digestibility. Rate and efficiency of gain in rats were used to evaluate the effects of autoclaving unextracted sunflower seeds at 115°C with 1.05 kg/cm² pressure for 0, 5 or 10 minutes. Rats fed on the basal maize-soya bean meal diet gained significantly faster and more efficiently than the rats fed on the diets containing the sunflower seeds. An increase in heating time of the sunflower seeds produced a significant reduction in rate and efficiency of rat gain.     

Influence of micronization (fine grinding) of soya bean meal and full-fat soya bean on the ileal digestibility of amino acids for broilers

A trial was conducted to test the effect of fine grinding (micronization) of soya bean meal (SBM) and full-fat soya bean (FFSB) on coefficient of ileal apparent digestibility (CIAD) and coefficient of ileal true digestibility (CITD) of amino acids in 23-day-old broilers. A completely randomized block design with four treatments arranged factorially (SBM and FFSB; micronized and ground) and six replicates (eight broilers per treatment) was used. Mean particle size (MPS) was 47 and 41 μm for micronized SBM and FFSB and 881 and 778 μm for ground SBM and FFSB, respectively. The four diets were based on maize starch and sucrose with the soya product tested as the sole source of dietary crude protein (CP, 200 g/kg). In addition, a nitrogen-free diet was formulated to estimate the basal ileal endogenous losses of the amino acids. Broilers were fed a commercial pelleted maize-SBM diet from 1 to 19 days of age and, then, their respective experimental diets in mash form from 20 to 23 days of age. Broilers fed SBM had higher CIAD of organic matter, CP, arginine, leucine, methionine and valine (P<0.05) and tended to have higher CIAD of threonine (P<0.10) than broilers fed FFSB. In addition, broilers fed SBM had higher CITD of CP (P<0.05), leucine, methionine and valine (P<0.01) than broilers fed FFSB. Particle size did not affect the ileal digestibility of CP or of any of the essential amino acids. It is concluded that broilers fed soya bean meal had higher ileal digestibility of amino acids than broilers fed full-fat soya bean and that fine grinding of the soya products did not affect amino acid digestibility.     

Alkali treatment of straw for ruminants. I. Utilization of complete diets containing straw by beef cattle

In the first of two experiments, 40 Friesian steers weighing initially 300 kg were fattened on diets containing barley and soya bean meal alone (C) or with inclusions of 40% untreated straw (WS₄₀) or 40 or 60% alkali-treated straw (AS₄₀ and AS₆₀). The straw was coarsely milled into a horizontal mixer, where sodium hydroxide was applied as a 16% solution providing $\text{80}\text{kg NaOH}\text{t straw dry matter (DM)}$. Intakes of DM (kg/d) were: C, 7.88; AS₄₀, 9.67; AS₆₀, 9.23; WS₄₀, 8.60, and empty body weight gains (kg/d, in the same order) were 1.16, 1.03, 0.82 and 0.78.In the second experiment there were four diets, all containing 60% straw and 40% concentrates. The straw was coarsely milled (M) or chopped by forage harvester (C), and treated with alkali (A) or untreated (U). In a trial of latin square design, intake (kg DM/d) was; MU, 7.77; MA, 10.37; CU, 7.44; CA, 10.12. In a longer trial with five steers per diet, liveweight gains (kg/d, in the same order) were 0.70, 1.09, 0.71 and 1.18. The digestibility of DM for the four diets was 60.0, 72.7, 60.3 and 72.0%.The utilization of the energy of the diets, and the economic value of alkali treatment, are discussed.     

Improving utilization of crop residues. Evaluation of two chemicals used to improve digestibility of crop residues

Two chemical treatments involving chelating metal caustic swelling (CMCS) and sodium hydroxide (NaOH) were evaluated for their ability to affect in vitro dry matter and in vitro cellulose disappearance (IVDMD and IVCD, respectively), dry matter disappearance in sacco and the chemical composition of two low-quality crop residues, cornstalks (CS) and soya bean residue (SBR). At $\text{chemical}\text{substrate}$ ratios ranging from 0.25:1 to 5:1, linear increases in IVCD of both roughages were noted. Improvements in IVCD of CS and SBR were noted at 1:1, 3:1 and 5:1$\text{chemical}\text{substrate}$ ratios, regardless of whether the treated roughages were used immediately after treatment (fresh basis) or preserved by drying or freezing. Decreased concentrations of neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and crude protein (CP) resulted from chemical treatment. No effects of the water component of the solvent solutions were observed. Dry matter disappearance in sacco of CMCS- and NaOH-treated roughages was increased at all $\text{chemical}\text{substrate}$ ratios tested. Treatment of either roughage with CMCS resulted in greater digestibility in sacco than did treatment with NaOH. Treatment of CS with CMCS resulted in higher rates of digestion than did treatment with NaOH. No differences in rates of digestion of SBR were noted between chemicals. Both chemicals were more effective in improving digestibility of CS than of SBR.     

Influence of source and micronization of soya bean meal on growth performance,nutrient digestibility and ileal mucosal morphology of Iberian piglets

The effects of inclusion in the diet of different sources of soya bean meal (SBM) on growth performance, total tract apparent digestibility (TTAD) and apparent ileal digestibility (AID) of major dietary components and mucosal ileum morphology were studied in Iberian pigs weaned at 30 days of age. From 30 to 51 days of age (phase I), there was a control diet based on regular soya bean meal (R-SBM; 44% CP) of Argentina (ARG) origin and five extra diets in which a high-protein soya bean meal (HP-SBM; 49% CP) of the USA or ARG origin, either ground (990 μm) or micronized (60 μm), or a soya protein concentrate (SPC; 65% CP) substituted the R-SBM. From 51 to 61 days of age (phase II), all pigs were fed a common commercial diet in mash form. The following pre-planned orthogonal contrasts were conducted: (1) R-SBM v. all the other diets, (2) SPC v. all the HP-SBM diets, (3) micronized HP-SBM v. ground HP-SBM, (4) HP-SBM of ARG origin v. HP-SBM of US origin and (5) interaction between source and the degree of grinding of the HP-SBM. Dietary treatment did not affect growth performance of the pigs at any age but from 30 to 51 days of age, post weaning diarrhoea (PWD) was higher (P<0.001) and the TTAD and AID of all nutrients were lower for pigs fed the R-SBM diet than for pigs fed the HP-SBM or the SPC diets. However, no differences between the HP-SBM and the SPC containing diets were detected for any trait. The TTAD of organic matter (P=0.07) and gross energy (GE) (P=0.05) tended to be higher for the micronized HP-SBM than for the ground HP-SBM and that of GE was higher (P<0.05) for US meal than for the ARG meal. Pigs fed R-SBM had lower villus height (P<0.01) than pigs fed HP-SBM or SPC but no differences in ileal mucosal morphology were detected between SPC and HP-SBM containing diets. It is concluded that feeding the HP-SBM or SPC-reduced PWD and improved nutrient digestibility and ileal morphology as compared with feeding the R-SBM, but had no effect on pig performance. The inclusion in the diet of added value soya products (micronized SBM or SPC) in substitution of the R-SBM increased the TTAD of all nutrients and reduced PWD but had no advantage in terms of growth performance over the use of ground HP-SBM.     

The effect of high levels of molasses in combinations with hay on digestibility of organic matter,microbial protein synthesis and volatile fatty acid production in vitro

Fermentation in vitro of $\text{0}\text{100}$, $\text{10}\text{90}$, $\text{40}\text{60}$ and $\text{70}\text{30}$ cane molasses/hay mixtures in media containing urea, trace minerals and vitamins showed a progressive improvement of digestible organic matter in vitro (INVDOM) of hay as the level of molasses increased. Replacement of urea by soya bean meal induced a lower INVDOM of hay in the mixture with 70% molasses.Structural carbohydrates (hay) induced higher microbial synthesis per unit digestible organic matter (DOM) than simple sugars (molasses).The results observed emphasized the importance of adding urea to molasses for improved digestion of hay and a higher percentagge of propionic acid in the rumen. The effect of formulation of molasses/hay rations with soya bean meal or urea on the pattern of fermentation is discussed.     

Ammonia and sodium hydroxide treatment of wheat straw in diets for fattening steers

The effects of treating Neepawa wheat straw with anhydrous ammonia (35 kg t^?1), sodium hydroxide (50 kg t^?1) and pelleting were evaluated in two experiments. The diets consisted of 51% rolled barley, 40% straw, 4% rapeseed meal, 2% tallow, plus minerals and a vitamin supplement. Straw was treated as follows: (1) shredded into 2.0-cm lengths; (2) shredded into 0.64-cm lengths and pelleted; (3) ammoniated and shredded; (4) ammoniated and pelleted; (5) sodium hydroxide and pelleted; (6) ammoniated, sodium hydroxide and pelleted.Apparent digestibility was measured with six steers per treatment. Pelleting had no effect on organic matter (OM) digestibility, but decreased neutral detergent fibre (NDF) and cellulose digestion. Respective increases for OM and NDF digestibility following chemical treatment of the straw were as follows: ammoniation — 15 and 17%; sodium hydroxide — 4 and 13%.The six diets were given to 144 Hereford steers (240 kg) for 92 days in the second experiment. Feed consumption ranged from 8.51 to 10.39 kg day^?1 for diets 1 and 4, and body weight gains ranged from 0.83 to 1.26 kg day^?1 for diets 1 and 6, respectively. Respective increases for intake, gain and feed efficiency compared to untreated shredded straw were as follows: pelleting — 11, 34 and 17%; ammoniation — 12, 36 and 17%. Sodium hydroxide treatment prior to pelleting improved intake, gain and feed efficiency by 5, 10 and 5%, respectively. There was no evidence of additive effects between ammoniation and either pelleting or alkali treatment, though treatment with sodium hydroxide prior to pelleting did result in the highest gains and feed efficiency.     

Effects of milling and pelleting of maize,barley and wheat on their metabolizable energy value for cockerels and chicks

Metabolizable energy (ME) measurements were made on chicks and cockerels on diets comprising 770 g/kg of maize, barley or wheat milled to three moduli of fineness and given either as a mash or pelleted and crumbled.There were significant differences in ME among grains, between diet forms, and with age of bird. With chicks, ME (MJ/kg dry matter (DM)) of all three diets was lower for the mash form (13.98) than for the pelleted and crumbled (14.29), but with cockerels pelleting increased ME only with the wheat diets. The oil content of the grains was influenced by treatment. The pelleted diets contained more oil than those in mash and crumbled forms. These oil contents did not explain differences in the ME of the different treatments.Since there was no effect of modulus of fineness on ME, it was concluded that coarse milling was adequate and could reduce the cost of diet preparation.     

Effects of feed form and energy levels on growth performance,carcass yield and nutrient digestibility in broilers

Feed form is well recognized to improve broiler performance, specially by increasing feed intake (FI). However, when different diet energy levels are used, the results differ in the literature. Therefore, this experiment was conducted to evaluate the influence of feed form and dietary metabolizable energy (ME) levels on broiler performance, carcass yield and on the digestibility of DM, CP, starch and gross energy. In total, 1152 male Cobb 500 broilers were evaluated between 35 and 47 days. The birds were distributed according to a completely randomized design in a 2 × 4 factorial arrangement, consisting of two feed forms (mash or pellet) and four ME levels (12.73, 13.06, 13.40 or 13.73 MJ/kg), totaling eight treatments with eight replicates of 18 birds. Broilers fed the lowest ME level presented the lowest weight gain (WG) and worst feed per unit gain (P < 0.01). Metabolizable energy intake increased (P < 0.01) with progressive increments of ME, which, however, did not affect caloric conversion (CC, P > 0.05). Pelleted diets promoted higher FI, WG, ME intake (P < 0.01) and better feed per unit gain and CC (P < 0.05) compared with mash. In mash diets, increasing dietary ME levels promoted a linear increase in WG (P < 0.01) and reduced feed per unit gain (P ≤ 0.05), but did not affect FI (P > 0.05). In pelleted diets, on the other hand, increasing ME levels linearly reduced FI (P < 0.05) and feed per unit gain (P < 0.01). Broilers fed pelleted diets presented higher abdominal fat deposition than those fed mash (P < 0.05). Increasing ME levels reduced the coefficients of ileal apparent digestibility of DM (P < 0.01) and total starch (P < 0.05) but did not affect the digestibility of other evaluated nutrients. The digestibility of all nutrients was lower when pelleted diets were fed compared with mash. Increasing inert material inclusion in the diets at the expense of soybean oil to reduce dietary ME levels promoted higher pellet durability index values (P < 0.05) and the percentage of fines (P < 0.01). Overall, the results suggest that pelleted diets promote better broiler performance because they increase FI, since the digestibility of dietary fractions is reduced. Chickens consuming low-energy pelleted diets may increase FI to compensate for energy deficit. In contrast, broilers fed mash diets may have reached their maximum intake capacity and did not regulate FI by changing feed energy density. When feeding pelleted diets, dietary energy reduction should be considered to reduce feed costs and to improve the carcass quality of broilers.     

Effects of micronization on the digestibility of whole soya beans and rapeseeds for the growing pig

Whole soya beans (S) and rapeseeds (R) (high glucosinolate/high erucic acid Brassica campestris and Brassica napus mixture) were heated under the ceramics of a micronizing machine for 90 seconds to give a terminal temperature of 196°C, and were then flaked, cooled and ground. The digestibility of diets containing these micronized whole seeds (MS and MR) was compared with that of diets containing equivalent proportions of meals (SM and RSM) and oils (SO and RO) extracted from the seeds (SMSO and RSMO treatments). A total of 72 caged pigs of 25 kg live weight were used.Micronization reduced the urease activity of MS and the levels of isothiocyanates and oxazolidinethiones of MR. The digestibility coefficients of diets containing MS and SMSO were similar but the digestibility of the crude oil of the MS (after correction for endogenous faecal lipids) was significantly poorer than that of the SO included alone. The digestible energy values (MJ/kg DM) were MS, 21.9 ± 1.19; SMSO, 21.6 ± 1.19; SM, 20.1 ± 2.17; SO, 35.7 ± 5.06. Overall, the apparent digestibility of the MR was poorer than that of the RSMO. The digestible energy content (MJ/kg DM) of the MR was 16.7 ± 0.93 and that of the RSMO, 20.8 ± 1.27. The individual digestible energy values (MJ/kg DM) of the RSM and RO were 25.3 ± 2.17 and 32.5 ± 1.90, respectively.     

The effect of steam-conditioning rate on the pelleting process

A poultry layer-diet was used in experiments to determine the effects of steam-conditioning level on pelleting variables. Dry pelleting was compared with steam conditioning (to 65 and 80° C) before pelleting, at both constant and maximum production rates. Samples were obtained before and after conditioning, and after pelleting. Electrical energy used by the pellet mill was measured with a watt-hour meter, and the amount of steam used for conditioning was calculated using steam tables. Temperature rise of the meal being extruded through the die and electrical energy required to pellet showed that steam decreased mechanical friction during pelleting. Pellet durability and percentage of fines from the scalper showed that steam improved pellet quality. Pressing the mash through the pellet die caused more starch damage during dry pelleting than during steam pelleting. Starch was not damaged during the steam-conditioning process. Total energy required for pelleting (electrical plus steam) was highest for the 80° C treatment. However, steam conditioning allows increased production rates and improved pellet durability during handling and transportation of finished feeds.