Dietary Particle Size Research Articles

Effects of diet particle size on digestive parameters in D+ and D− genetic chicken lines selected for divergent digestion efficiency

The aim of this experiment was to compare the D(+) and D(-) chicken lines genetically selected for divergent digestion efficiency by testing the effects of diet particle size on growth performances, digestion efficiencies, and digestive organ weights in both lines. A 2 x 3 factorial arrangement of treatments was used to test the D(+) and D(-) lines (sixth generation) and 3 diets, namely a pelleted standard corn diet (S), a pelleted hull diet (H) made by diluting S diet with 7% coarse cereal hulls, and a coarse corn diet (C) identical to the S diet, distributed as 30% coarsely crushed corn mixed with the 70% pelleted remaining part. Experimental diets were fed from 7 to 26 d of age. Combining results from all diets obtained at 26 d of age, D(+) birds showed 9% heavier (P < 0.0001) gizzard and 10% lighter (P < 0.0001) small intestine than D(-) birds. The AME(n) and digestibilities of lipids, protein, and starch measured at 3 wk of age were, on average, 3.5, 5.6, 5.8, and 0.5% higher (P < 0.0002) in D(+) than in D(-) birds, respectively. Significant (P </= 0.05) interactions between lines and diets were observed for AME(n) and digestibility values. Measured:calculated AME(n) ratio and digestibilities of protein and starch were improved (P < 0.05) by dietary coarse particles in D(-) birds, not in D(+) birds. Measured:calculated AME(n) ratio differed between lines by 6.0% with S diet versus 2.3% with H and C diets. In D(-) birds, the digestion increases due to coarse particles were associated with increased weights of gizzard (P < 0.0001) and pancreas (P < 0.05). In D(+) birds, coarse particles resulted in increased weights of gizzard (P < 0.0001) only. In conclusion, growth and functions of gizzard and pancreas needed to be stimulated by dietary coarse particles for optimum digestion efficiencies in D(-) chickens, whereas such stimulations were not needed in D(+) chickens. The D(+) chickens showed high digestion efficiencies in all cases, independently of diet particle size.

Decreasing dietary particle size of lupins increases apparent ileal amino acid digestibility and alters fermentation characteristics in the gastrointestinal tract of pigs

Two experiments were conducted to examine the effects of lupin particle size on amino acid (AA) and energy digestibility and fermentation characteristics in pigs. Expt 1 examined the effects of lupin variety (cv. Tanjil and Mandelup) and lupin particle size (746, 888, 1099 and 1136 mum) on the total-tract apparent digestibility of dietary components in 63.5 (sd 7.28) kg pigs. While variety had no effect on total-tract apparent digestibility, decreasing particle size of lupins linearly increased total-tract apparent digestibility of crude protein of diets containing 350 g lupins per kg (P < 0.01). Expt 2 examined the effect of lupin particle size (567, 995, 1198, 1250 and 1304 mum) on digestion and fermentation characteristics in 29.8 (sd 2.9) kg pigs. Pigs were fed the respective diets ad libitum for the first 2 weeks and fed at three times maintenance energy level in the third week. Pigs were euthanised under sedation at 46.7 (sd 4.21) kg to collect digesta samples along the intestinal tract. Decreasing particle size increased apparent ileal and total-tract digestible N (P < 0.01) and the apparent and standardised ileal digestible AA content (P < 0.05- < 0.001) of lupins. Decreasing particle size of lupins linearly decreased the molar proportion of straight-chain volatile fatty acids (sum of acetic, propionic and butyric acids; VFAAPB), while branched-chain fatty acids (sum of valeric, caproic, isobutyric and isovaleric acids) were linearly increased (P < 0.001). The results demonstrated that particle size of lupins is a critical factor influencing nutrient, especially AA, utilisation efficiency and fermentation characteristics in the gastrointestinal tract of pigs.

Effects of meal or pellet diet form on finishing pig performance and carcass characteristics (2009)

Two experiments were performed to determine the effects of feeding diets in meal or pellet form on finishing pig performance. A corn-soybean meal-based diet was fed in Exp. 1, and a diet containing alternative ingredients was used in Exp. 2. All pelleted diets were processed through a CPM pellet mill (California Pellet Mill Co., Crawfordsville,IN) equipped with a 3/16 in. die. In Exp. 1, a total of 1,072 pigs (60.7 lb) were used in a 112-d trial. Treatments were arranged in 2 × 2 factorial design (10 pens per treatment) with main effects of diet form (meal or pellet) and gender (barrows or gilts). Diet formulation and particle size (approximately 660 microns) was identical among the treatments. From d 0 to 112, pigs fed pelleted diets had increased ADG (2.04 vs. 1.92 lb, P < 0.01) compared with pigs fed diets in meal form. There was no difference (P = 0.69) in ADFI, but pigs fed pelleted diets had a 5.3% improvement (2.68 vs. 2.83, P < 0.01) in F/G compared with pigs fed meal diets. With the improvements in F/G driving the growth response, pigs fed pellets were 13.6 lb heavier (P < 0.01) at off test than pigs fed meal diets. In Exp. 2, a total of 1,214 pigs (58.3 lb) were used in a 42-d trial to evaluate diets containing alternative ingredients in pellet or meal form. Barrow and gilt pens were randomly allotted to a meal or pellet treatment group (11 pens per treatment). Like Exp. 1, diet particle size (approximately 660 microns) and formulation were identical among the treatments. Pigs fed a by-product-based diet in pellet form had greater (2.05 vs. 1.95 lb, P < 0.01) ADG than pigs fed the identical diet in meal form. There were no differences (P ≥ 0.15) in overall (d 0 to 42) ADFI or F/G between pigs fed meal and pelleted diets. Pigs fed pelleted diets had a numerical (P = 0.14) weight advantage of 4.1 lb on d 42 compared with pigs fed meal diets. These data demonstrate that feeding a pelleted diet improved ADG compared with feeding a meal diet; however, the magnitude of the response was inconsistent between trials. In addition, F/G was improved by pelleting in the first trial, with no effect found in the second trial. One explanation for this difference might be the quality of the pellets. Samples of the pelleted diets collected in Exp. 1 contained approximately 25% fines, whereas samples of the pelleted diets in Exp. 2 were composed of approximately 35% fines. Diets formulation (corn-soybean vs. corn-alternative ingredients) can influence pellet quality, which may explain differences between the experiments.; Swine Day, Manhattan, KS, November 19, 2009

Effect of out-of-feed events and diet particle size on pig performance and welfare

Objective: To determine the impact of repeated out-of-feed events on pig performance. Materials and methods: In each of two experiments, out-of-feed events of 20-hour duration were created by closing the feeder delivery devices from noon until 8:00 am the following morning. In Experiment One, the treatments were never or weekly out-of-feed events for a 16-week period, and 1266-micron versus 1019-micron mash feed-particle size. In Experiment Two, the treatments were zero, one, two, or three out-of-feed events on random days every 2-week period in the 16-week study. In each experiment, there were four pens per treatment combination or treatment and 15 pigs per pen. Results: Weekly events resulted in a 68-g per day lower daily gain for the first 8 weeks (growing period; P &lt; .001), and 35-g per day lower gain over the entire trial (P &lt; .01), compared to the never out-of-feed treatment, with no impact on feed conversion (P &gt; .05). Feed conversion was better when feed particle size was 1019 microns versus 1266 microns (P &lt; .01). In Experiment Two, there was a linear decrease in daily gain with increasing numbers of out-of-feed events during the first 8-week period (P &lt; .01), with no impact during the second 8-week period. There was no effect of treatments on feed conversion. Implications: Repeated out-of-feed events have a bigger impact on growing pigs than on finishing pigs, with the impact expressed as lower weight gain with no effect on feed conversion.

Effects of Particle Size of Barley on Intestinal Morphology, Growth Performance and Nutrient Digestibility in Pigs

A growth trial and a digestibility trial were conducted to examine the effect of feed particle size on the performance, nutrient digestibility, gastric ulceration and intestinal morphology in pigs fed barley-based diets. Barley was processed through a hammer mill to achieve four diets varying in particle size (average particle size+standard deviation): coarse (1,100±2.19 μm), medium (785±2.23 μm), fine (434+1.70 μm) and mixed (1/3 of coarse, medium and fine) (789+2.45 μm). Sixty-four entire male pigs were used in the growth trial and the diets were fed ad libitum between 31 kg and 87 kg live weight. Following slaughter, stomach and ileal tissues were scored for integrity (ulceration or damage) and histological measurements taken. Twenty-four entire male pigs were used in the digestibility trial, which involved total faecal collection. Over the entire growth phase, there were no differences (p>0.05) in average daily gain and feed conversion ratio between pigs fed diets of different particle size. Pigs fed the coarse and medium diets had lower (p 0.05) being observed for villous height or crypt depth. Faecal digestibility coefficients of neutral and acid detergent fibre were the highest (p<0.05) for the mixed diet, intermediate for the fine and coarse diets and the lowest for the medium diet. A similar numerical trend (p = 0.103) was observed for the apparent faecal energy digestibility coefficient. It is concluded that, with barley based diets, a variation in average particle size between 400 μm and 1,100 μm had no effect on pig performance but the fine dietary particle size affected the integrity of the stomach, as well as the structure of the small intestine, thus compromising overall gut health. Our data also demonstrate that changes in particle size distribution during the digestion process, rather than average particle size or particle size variation, are related to apparent faecal digestibility.

Review of a histological intestinal approach to assessing the intestinal function in chickens and pigs

ABSTRACTThe general histological features of the small intestine are well known. However, histological intestinal alterations induced by ingested feeds have not been established. To demonstrate such a relationship; (i) the post‐hatching development of intestinal villi in chickens was observed; (ii) histological intestinal differences were compared in White Leghorns and broilers; and (iii) histological intestinal alteration was investigated in fasting and refeeding treatments, using chickens and piglets. Histological intestinal recovery responses; (iv) to luminal nutrient absorption, intraluminal physical stimulation, or intravenous parenteral alimentation in fasted chickens, as well as; (v) to particle size and nutritional level of refed diets in fasted chickens and piglets were also compared. To induce compensatory enlargement of ileal villi; (vi) the jejunum was surgically resected. To reconfirm the histological intestinal alterations induced artificially; (vii) conventional feeding experiments were enforced in chickens and piglets. These fundamental investigations demonstrate that the high values of villus height, cell area and cell mitosis numbers as well as protuberated epithelial cells are hypertrophied by ingested feeds. Finally, as examples of practical use in the animal production field; (viii) useful feed resources to improve the growth performance by activating the intestinal function in chickens and piglets; and (ix) an effective forced molting method are introduced. Based on the histological intestinal alterations related with growth performance in chickens and piglets, this article reviews progress in the establishment of a histological intestinal index to assess the intestinal function.

Influence of Feed Form on Gizzard Morphology and Particle Size Spectra of Duodenal Digesta in Broiler Chickens

We examined gizzard morphology and diet particle size reduction in broiler chickens fed a wheat-based diet that was offered in either a mash or a pelleted form. The pelleted diet had a lower proportion of coarse particles on wet sieving. Birds fed the mash diet had a significantly larger gizzard mass per unit body mass. The gizzards of all birds increased uniformly in size, there being no significant change either in the ratio of content to empty mass or in the ratio of gizzard length to breadth with diet. Thus, there was no tendency for coarse particles to accumulate in the gizzards of bird fed the mash diet. The relative proportion of all classes of particles below 0.500mm was increased and the relative proportion of all particle classes above 0.500mm was reduced in birds regardless of feed form. The relative increase of particles in all classes below 0.500mm was greater in birds fed mash feed. However, digesta exiting the gizzard of birds fed mash diet contained significantly greater amounts of particles of size classes 1mm and greater than digesta of those fed the pelleted diet. Thus, whilst the gizzard operates to generally reduce particle sizes above 0.500mm and increase those below this size, this reduction is not uniform and likely to be a probabilistic function as it is in the human mouth.

Granulometria do calcário no desempenho e qualidade da casca de ovos de codornas japonesas

This experiment evaluated limestone particle size of diet on performance and shell quality of japanese quails. The experimental design used was completely randomized with five treatments (five different particle sizes of limestone) and five replicates of 16 birds each in a total of 400 birds. The treatments were: T1 – Diets with 100% of the limestone coarse; T2 – diets with 70% of limestone coarse and 30% fine; T3 – diets with 30% of limestone coarse and 70% fine; T4 - Diets with 100% of the limestone fine and T5 – Diets with 100% of medium limestone. The experimental diets were formulated to meet NRC (1994) nutritional requirements. The treatment of 100% fine particle size improved egg production and bird performance compared to the treatment with 100% medium particle size. There was no effect of limestone particle size on shell quality of quail eggs. The fine or coarse limestone particle size can be used in diets of laying quails. The medium limestone particle size is not recommended on laying Japanese quail diets. KEY WORDS: Limestone, particle size, japonese quails, egg production, shell egg quality.

Effects of Particle Size and Physical Form of Diets on Mast Cell Numbers, Histamine, and Stem Cell Factor Concentration in the Small Intestine of Broiler Chickens

The aim of this study was to investigate the hypothesis that particle size and diet form may affect the growth of mast cells and histamine release from the small intestine of broiler chickens. A total of 288, day-old male broiler chicks were randomly allocated to 1 of 4 corn-soy diets in a 2 × 2 factorial design. The factors included particle size (coarse vs. fine) and physical form (mash vs. pellet). The birds were housed in 90 × 60 cm pens containing 12 birds, and each treatment contained 6 replicate pens of birds from d 1 to 22. On d 22, 6 broilers from each treatment were slaughtered. Tissues from the small intestine (duodenum, jejunum, and ileum) were obtained to quantify mast cells using the toluidine blue staining technique. The results showed that mast cells in the jejunum were concentrated in the upper part of the villus in birds fed the coarsely ground mash diet, whereas mast cells were evenly distributed throughout the intestine in birds fed the other 3 diets. The number of mast cells was significantly lower in the duodenum (P = 0.04), jejunum (P < 0.01), and ileum (P = 0.01) of birds fed coarsely ground diets compared with finely ground diets, and there was no difference in mast cell numbers between birds fed mashed or pelleted diets at any site in the intestine. The histamine content (P = 0.02) and stem cell factor concentration (P = 0.03) were markedly lower in the jejunum of birds that were fed coarsely ground diets compared with finely ground diets. The stem cell factor concentration in the duodenum (P < 0.01) and jejunum (P = 0.05) was higher in birds fed pelleted compared with mash diets. The overall results of this experiment suggest that particle size and diet form affect mast cell number and histamine content in the small intestine by regulation of stem cell factor concentration.

Effect of the calcium level and limestone particle size on the performance of semi-heavy layers in the second cycle of egg production

An experiment was carried out at the Research and Development Unit of Brotas aiming at evaluating dietary calcium level and limestone particle size on the production performance of commercial (Hy-Line Brown) layers in the second lay cycle. Experiment duration was 112 days. A total number of 288 hens, with 83 weeks of age in the beginning of the experiment, were used in a completely randomized experimental design in a factorial arrangement of 2x3, with two calcium levels (3.5 and 4.0%) and three limestone particle size compositions: 100% fine limestone (FL), 30% coarse limestone (CL) + 70% fine limestone (FL), and 50% (CL) + 50% (FL), with six replicates of eight birds each. Egg weight (g), egg production (%), egg mass (%), feed intake (g), feed conversion ratio (kg/dz and kg/kg), mortality (%), and egg loss (%) were evaluated. The analysis of variance did not detect significant differences (p>0.05) among treatments on any of the evaluated performance parameters. It was concluded that the tested calcium levels and limestone particle composition did not influence the performance of semi-heavy layers in second production cycle.

Effect of Corn Particle Size and Pellet Texture on Broiler Performance in the Growing Phase

A review of past literature revealed inconsistencies in recommended grain particle size for optimal broiler performance. Changing diet formulation and subsequent processing variables may alter pellet texture and potentially affect broiler performance. In the current study, ground corn, varying in size (781, 950, 1,042, 1,109, and 2,242 μm), was added to a soybean-based premix to create 5 different mash diets. Water and a commercial pellet binder were added separately to corn-soybean-based diets before steam pelleting to create 2 pelleted diets differing in texture (soft and hard, respectively). The objective was to evaluate corn particle size, pellet texture, and feed form variation of compound diets on 3- to 6-wk broiler performance, nutrient retention, carcass characteristics, TMEn, feed passage time, and particle size preference. Soft and hard pellets had similar pellet durability (90.4 and 86.2%, respectively) and fines (44.5 and 40.3%, respectively). Increasing particle size of mash diets improved nutrient retention. However, broiler performance and energy metabolism were decreased when corn particle size exceeded 1,042 μm. This observation was due, in part, to increased size and maintenance requirement of the gastrointestinal tract. Broilers fed hard pellets (1,856 g of pellet breaking force) had improved nutrient retention, TMEn, and subsequent performance compared with broilers fed soft pellets (1,662 g of pellet breaking force). Pellet texture may affect broilers in a manner similar to particle size.

Increasing the Physically Effective Fiber Content of Dairy Cow Diets May Lower Efficiency of Feed Use

Barley silages varying in theoretical chop length were used to evaluate the effects of physically effective (pe) neutral detergent fiber (NDF) content of dairy cow diets on nutrient intakes, site and extent of digestion, microbial protein synthesis, and milk production. The experiment was designed as a replicated 3×3 Latin square using 6 lactating dairy cows with ruminal and duodenal cannulas. During each of 3 periods, cows were offered 1 of 3 diets (low, medium, and high peNDF) obtained using barley silage that varied in particle length: fine (theoretical chop length of 4.8mm), medium (equal proportions of long and fine silages), and long (theoretical chop length of 9.5mm). The peNDF contents were determined by multiplying the proportion (dry matter basis) of feed retained on the 2 screens (8 and 19mm) of the Penn State Particle Separator by the NDF content of the diet, and were 10.5, 11.8, and 13.8% for the low, medium, and high diets, respectively. Increased forage particle length linearly increased intake of peNDF but intakes of dry matter, organic matter, starch, and N were highest for cows fed the medium peNDF diet. Digestibilities of organic matter, NDF, and acid detergent fiber in the total tract were linearly decreased with increasing dietary peNDF, although total digestibility of starch and N was not affected by the treatments. Nevertheless, decreased digestibility due to increased dietary peNDF did not reduce milk production or milk composition because the cows were in mid to late lactation. Ruminal microbial protein synthesis and microbial efficiency were numerically higher with the low peNDF than with the medium or high peNDF diets. These results indicate that increasing the peNDF content of a diet containing barley silage decreases fiber digestibility in the total tract and lowers microbial efficiency. Therefore, the benefits of increasing dietary particle size, expressed as peNDF, on reducing the risk of ruminal acidosis should be weighed against potentially negative effects on efficiency of feed use.

Effect of a reduction of dietary particle size by substituting a mixture of fibrous by-products for lucerne hay on performance and digestion of growing rabbits and lactating does

The effect of a reduction of dietary particle size by the substitution of a mixture of paprika meal, sugar-beet pulp and soya bean hulls for lucerne hay was evaluated in rabbits. Four isonutritive diets were formulated containing a decreasing proportion of large particles (> 0.315 mm) 24.1%, 22.0%, 20.6% and 18.9%. Nutrient digestibility, caecotrophy and caecal traits were determined using 9 growing rabbits per diet. Growth and lactation performance was determined in 45 weanling rabbits and 13 rabbit does per diet, respectively. The diet with the shortest particle size increased by 20% the weight of caecal contents and reduced feed intake of fattening rabbits, lactating does and suckling rabbits (21–30 d of age) by 7%, 10% and 30%, respectively, with respect to the average of the other three diets. It also decreased growth in fattening rabbits, milk production and litter weight at weaning by 6%, 13% and 18%, respectively. Feed efficiency decreased by 7% in rabbit does and was not affected during fattening, as the decrease in performance was parallel to a higher (+ 3%) digestible energy concentration in this diet. Reduction of particle size also increased NDF digestibility and caecal volatile fatty acid concentration. It is concluded that a minimal proportion of large particles (> 0.315 mm) of 20.6% is required to maximise growth and lactation performance in rabbits.

Effects of Physically Effective Fiber on Chewing Activity and Ruminal pH of Dairy Cows Fed Diets Based on Barley Silage

The objective of this study was to investigate the effects of physically effective neutral detergent fiber (peNDF) content of dairy cow diets containing barley silage as the sole forage source on feed intake, chewing activity, and ruminal pH. The experiment was designed as a replicated 3×3 Latin square using 6 lactating dairy cows with ruminal cannulas. Cows were offered 1 of 3 diets (high, medium, and low peNDF) obtained using barley silage that varied in particle length: long (theoretical cut length of 9.5mm), medium (equal proportions of long and fine silages), and fine (theoretical cut length of 4.8mm). The peNDF contents were determined using the Penn State Particle Separator and were 13.8, 11.8, and 10.5%, for the high, medium, and low diets, respectively. The physical effectiveness factors (defined as proportion retained on 19- and 8-mm screens) for the long and fine silages were 0.84 and 0.68, respectively. Increased forage particle size increased intake of peNDF but did not affect intake of DM and NDF. Ruminating and total chewing time were linearly increased with increasing dietary peNDF. Mean ruminal pH, area between the curve and a horizontal line drawn at pH 5.8 or 5.5, and time that pH was below 5.8 or 5.5 were not affected by peNDF content. Intake of peNDF was not correlated to any chewing activity but proportion of long particles on the 19-mm sieve tended to be correlated to ruminating chews (r = 0.36) and ruminating time (r = 0.36). These results indicate that increasing the peNDF content of diets increases chewing time. However, increased chewing time does not always improve ruminal pH status. Increasing chewing time and thus increasing salivary secretion may not fully overcome the effects of feed digestion and the production of fermentation acids that lower rumen pH. The results suggest that dietary peNDF and fermentable OM intake are critical in regulating rumen pH. Dietary particle size, expressed as peNDF, was a reliable indication of chewing activity.

Effects of Physically Effective Fiber on Intake, Chewing Activity, and Ruminal Acidosis for Dairy Cows Fed Diets Based on Corn Silage

A study was conducted to investigate the effects of physically effective (pe) neutral detergent fiber (NDF) content of dairy cow diets containing corn silage as the sole forage type on feed intake, meal patterns, chewing activity, and rumen pH. The experiment was designed as a replicated 3×3 Latin square using 6 lactating dairy cows with ruminal cannulas. Diets were chemically similar but varied in peNDF content (high, medium, and low) by altering corn silage particle length. The physical effectiveness factors for the long (original), medium (rechopped once), and fine (rechopped twice) silages were determined using the Penn State Particle Separator and were 0.84, 0.73, and 0.67, respectively. The peNDF contents of the diets were 11.5, 10.3, and 8.9%, for the high, medium, and low diets, respectively. Increased forage particle length increased intake of peNDF but did not affect intake of DM or NDF. Number of chews (chews/d) and chewing time, including eating and ruminating time, were linearly increased with increasing dietary peNDF. Meal patterns were generally similar for all treatments, except that number of meals was quadratically increased with increasing dietary peNDF. Mean ruminal pH, area between the curve and a horizontal line at pH 5.8 or 5.5, and time that pH was below 5.8 or 5.5 were not affected by peNDF content. Dietary peNDF content was moderately correlated to number of chews during eating (r = 0.41) and to total chewing time (r = 0.37). The present study demonstrates that increasing the peNDF content of diets increased chewing time, but increased chewing time did not necessarily reduce ruminal acidosis. Models that predict rumen pH should include both peNDF and fermentable OM intake. Dietary particle size, expressed as peNDF, was a reliable indicator of chewing activity.

Effects of Physically Effective Fiber on Digestion and Milk Production by Dairy Cows Fed Diets Based on Corn Silage

Effects of physically effective (pe) neutral detergent fiber (NDF) content of dairy cow diets on nutrient intakes, site and extent of digestion, microbial protein synthesis and milk production were evaluated in a double 3×3 Latin square design using 6 lactating dairy cows with ruminal and duodenal cannulas. During each of 3 periods, cows were offered 1 of 3 diets that were chemically similar but varied in peNDF content (high, medium, and low) by altering corn silage particle length. The peNDF contents were determined using the Penn State Particle Separator and were 11.5, 10.3, and 8.9%, for the high, medium, and low diets, respectively, and the physical effectiveness factors for the long, medium, and fine silages were 84.1, 72.6, and 67.2%, respectively. Increased forage particle length increased intake of peNDF but did not affect intakes of nutrients including dry matter, NDF, starch, and nitrogen. Except for starch, apparent digestibilities of nutrients in the total tract were linearly increased with increasing dietary peNDF. Fiber digestion was affected by dietary peNDF to a greater extent than were the other nutrients. However, increased digestibility due to increased dietary peNDF did not significantly improve milk production or milk composition. Increased dietary peNDF also increased numerically rumen microbial protein synthesis due to increased amount of organic matter fermented in the rumen. These results indicate that increasing the peNDF content of a corn silage based diet improves digestibility, especially digestibility of fiber, in the total tract. Dietary particle size, expressed as peNDF, is positively associated with nutrient digestibility when level of peNDF in the diet is low.

Feeding installation for total mixed ration: effects on buffalo milk yield and composition

Chemical and physical characteristics of dietary forage are involved in determining feed intake as well as in maintaining proper rumen function. On this regard, feeding installations could contribute in reducing feed selection activity: the aim of this study was to evaluate in buffalo cows the effects of TMR administration on the floor (group C) or in a experimental feed bunk (group F) on dietary particle size (g fraction’s DM·100 g DM-1) at different times after TMR distribution, milk yield and chemical constituents (solids not fat, protein and fat content), total bacterial count (TBC) and somatic cell count (SCC). Twelve multiparous Mediterranean Italian buffaloes (100±23 DIM) were divided into the two groups; buffaloes were fed the same diet (17.0 kg DM·head-1), consisting of 0.79 UFL·kg DM-1, 470.0 g NDF·kg DM-1 and 110.6 g CP·kg DM-1. The particle size analysis of TMR residues (at 24 hours) shows a significant (P<0.05) selection activity against coarse particles (>19 mm) in C group (16.4±1.6 g DM·100 g DM-1 vs. 11.0±1.6 g DM·100 g DM-1). Besides, a lower activity in TMR selection against fine dietary particles (<8 mm) is observed in F than in C group (54.0±3.3 g DM·100 g DM-1 vs. 45.0±3.3 g DM·100 g DM-1) at the same time. Feeding selection activity against the less palatable dietary particles seems to be more evident when TMR was offered on the floor; the significant effect of feed installation on milk fat content (C: 6.09±0.32 g·100 g-1 of milk; F: 6.99±0.28 g·100 g-1 of milk) seems to confirm this hypothesis. Results suggest that feeding installation could therefore exploit dietary forages, by affecting physical efficiency of the ruminal ecosystem.The authors thank Antonio e Michele Caporaso (Azienda “Di Fusco Vincenza”, S. Angelo D’Alife, CE, Italy) for their cooperation. Research supported by the University of Molise, Italy.

Effects of particle size, processing, and dry or liquid feeding on performance of piglets

Currently, most feed grains are processed by either hammer mill or roller mill before the inclusion in pig diets. However, the effect of these two types of milling and particle size on the performance and feed utilisation has not been adequately examined. The effect of milling processing (hammer mill v. roller mill), particle size, and feeding method (liquid v. dry) was assessed in a factorial design with 120 weaner pigs over 21 days. These pigs had been weaned for 7 days when the experiment commenced. The results revealed that pigs fed on hammer-milled diets had a better performance than those on roller-milled diets. Particle size of hammer-milled diets did not affect the performance of pigs, but influenced the digestible energy content of the diets. However, the feed conversion ratio was poorer for pigs fed coarsely or medium roller-milled diets only at Day 7–14 after weaning. There was a marked advantage in terms of feed efficiency associated with liquid feeding. For pigs offered the hammer-milled diets between 0 and 14 days, simply adding the feed to water improved feed efficiency by some 22%. For the roller-milled diets the corresponding improvement in feed efficiency was 28%. Liquid feeding improved digestible energy (DE) value by 1.5 MJ/kg for medium particle size and depressed DE value by 0.8 MJ/kg for fine particle size for hammer mill. Liquid feeding improved DE values for both medium and fine particle treatments by 0.9 MJ/kg for roller-milled diets. It should be noted that the full advantages of liquid feeding could only be taken if feed wastage from this system can be minimised as much as possible.The study was conducted to investigate if processing method (roller v. hammer mill), particle size (coarse, medium, and fine), and feeding method (liquid v. dry) significantly improved the growth rate, feed intake, and feed conversion of the weaner pig.

Gastric dilatation-volvulus in dogs

Gastric dilatation-volvulus (GDV) is a disease in which there is gross distension of the stomach with fluid or gas and gastric malpositioning. It causes pathology of multiple organ systems and is rapidly fatal. It is common in large- and giant-breed dogs. The disease appears to have a familial predisposition. Thoracic depth/width ratio also appears to predispose dogs to GDV. Implicated dietary factors include dietary particle size, frequency of feeding, speed of eating, aerophagia and an elevated feed bowl. A fearful temperament and stressful events may also predispose dogs to GDV. Abdominal distension, non-productive retching, restlessness, signs of shock, tachypnoea and dyspnoea are possible clinical signs. Initial treatment includes treatment of shock and gastric decompression. Surgical treatment should be performed promptly. There are no studies comparing the use of different anaesthetic agents in the anaesthetic management of GDV. Pre-medication with an opioid/benzodiazepine combination has been recommended. Induction agents that cause minimal cardiovascular changes such as opioids, neuroactive steroidal agents and etomidate are recommended. Anaesthesia should be maintained with an inhalational agent. Surgical therapy involves decompression, correction of gastric malpositioning, debridement of necrotic tissue, and gastropexy. Options for gastropexy include incisional, tube, circumcostal, belt-loop, incorporating, and laparoscopic gastropexy. Expected mortality with surgical therapy is 15–24%. Prognostic factors include mental status on presentation, presence of gastric necrosis, presence of cardiac arrhythmia and plasma lactate levels. Prophylactic gastropexy should be considered in dogs identified as being at high risk.

Diet particle size preference and optimal ration for mud crab, Scylla serrata, larvae fed microbound diets

This paper reports on experiments to determine particle size preference and optimal ration for the various larval stages of the mud crab, Scylla serrata, fed microbound diets (MBD). All experiments used 14C-labelled rotifers as components of MBD, and ingestion was determined by assessing the 14C content of S. serrata larvae after feeding on the MBD. Five size ranges of MBD (< 150, 150–250, 250–400, 400–600 and 600–800 μm) were used to assess ingestion by Zoea I, Zoea III, Zoea V and Megalopa. All were fed a ration equivalent to twice the equivalent dry weight of live foods provided to each larval stage under standard rearing conditions (standard ration). MBD particle size preference increased with increasing larval development. Highest ingestion rates by Zoea I, Zoea III, Zoea V and Megalopa were found for particle size ranges of < 150, 150–250, 250–400 and 400–600 μm, respectively. MBD within these particle size ranges were used in subsequent experiments to assessed optimum rations for each of the four larval stages. Larvae were fed rations based on multiples or fractions of the standard ration (100%): 12.5%, 25%, 50%, 100%, 200% and 300%. There were no significant increases in ingestion, for any of the four larval stages, when ration was increased above 100%. For Zoea I, Zoea III and Zoea V larvae, there was no significant difference in the rate of MBD ingestion when ration was reduced to 50%; however, a 25% ration brought about a significant decrease in ingestion. There was no significant decrease in the rate of ingestion by Megalopa when ration was reduced from 100% to either 50%, 25% or 12.5%. The results suggest that rations currently used for larval rearing of S. serrata may be excessive. Little is currently known of the feeding behaviour and nutritional requirements of S. serrata larvae, and the results of this study are a significant development in this field.