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Cleavable linkers are designed to release the drug within or in the vicinity of the tumour cells upon a trigger stimulus. In recent years, there have been multiple reports of self-immolative cleavable linkers able to self-degrade in a spontaneous and irreversible manner through a cascade-elimination process. In general, this process is driven by an entropy increase and the formation of thermodynamically stable products and the control of the drug release is achieved by a stimulus such as an enzymatic cleavage of the linker that activates the self-immolative process. [1]We have designed and synthesized a new self-immolative bioorthogonal conditionally cleavable linker based on the Grob fragmentation that allowed the controlled release of sulfonate-containing compounds such as a dansyl group under physiological conditions. We have also tuned conveniently the pKa of the pushing group (amino group) using different substituents, leading to more efficient conversions at physiological pH and in some cases even at acidic pH, which is normally found in tumour environments. In addition, the Grob fragmentation takes place under physiological conditions in living cells, demonstrating the potential bioorthogonal applicability of the reaction. Based on these promising results, research is currently underway to incorporate this type of linker into antibodydrug conjugates for the targeted delivery of cytotoxic drugs and fluorophores.

The effects of feed form and dietary fiber on the development of the gastrointestinal tract (GIT) and nutrient digestibility were studied in broilers at 8 and 21 d of age. The experiment included 14 treatments arranged as a 2 × 7 factorial with 2 feed forms (mash vs. pellet) and 7 diets that consisted in a low fiber diet and 6 extra diets resulting from the combination of 3 insoluble fiber sources [oat hulls (OH), rice hulls, and sunflower hulls] and 2 levels of inclusion (2.5 and 5.0%). Pelleting decreased the relative weight (% BW) of the full GIT, and empty gizzard (P < 0.001) and the relative length (cm/kg empty BW) of the small intestine and ceca (P < 0.001) and increased full crop (P < 0.001) and liver (P < 0.05) weights. Fiber inclusion increased the empty weight and the fresh digesta content of the gizzard (P < 0.001) but had limited and inconsistent effects on the weight of the full GIT or the length of the small intestine and ceca. Gizzard pH decreased with mash feeding and fiber inclusion (P < 0.001). Pelleting decreased ether extract retention (P < 0.05) but did not affect N retention or AMEn of the diets. Fiber inclusion improved nutrient retention (P < 0.05 to P < 0.001) with more pronounced effects with OH than with sunflower hulls or rice hulls inclusion. The AMEn of the diets increased (P < 0.05) with 2.5% of fiber inclusion but no extra benefits were obtained with a further increase to 5.0%. Starch ileal digestibility increased with mash feeding (P < 0.001) and fiber supplementation (P < 0.05). In summary, pelleting increases full crop weight and gizzard pH and decreased full gizzard weight and starch ileal digestibility. Moderate amounts of insoluble fiber, especially OH, increases gizzard weight, reduces gizzard pH, and improves nutrient digestibility in young broilers.

A total of 648 straight-run hatchling Heritage 56M × fast feathering Cobb 500F broiler birds were used to determine the effects of Ca concentration and age on phytase efficacy. Corn and SBM based diets with 0.19% non-phytate P were prepared with three Ca (6.5, 8.0 and 9.5 g/kg) concentrations. A 6-phytase 5 was added on-top at 0, 500 or 1000 FTU/kg at each Ca concentration, resulting in a total of 9 treatments. Broiler birds were fed the diets for 2 d either from 7 to 9 (6 birds/replicate) or 19 to 21 (3 birds/replicate) d of age, and ileal content was collected from every bird at the end of each feeding period to determine apparent ileal digestibility coefficient (AID). Age effect was determined by comparing responses between birds fed from 7 to 9 and 19 to 21 d of age. There was no interaction between Ca and phytase on AID P regardless of age. Increasing Ca from 6.5 to 9.5 g/kg resulted in 12 (0.58 vs. 0.51) and 11% (0.64 vs. 0.57) reduction in AID P, in 9-d-old and 21-d-old birds, respectively (P

The effects of feed form and the inclusion of insoluble fiber in the diet on growth performance and water intake were studied in female broilers from 0 to 21 d of age. The experimental design was completely randomized with 14 treatments arranged as a 2 × 7 factorial with 2 feed forms (mash vs. pelleted) and 7 diets that consisted of a control diet low in fiber (1.6% crude fiber) based on broken rice, fermented soybean meal, and fish meal and 6 extra diets that resulted from the inclusion of 3 insoluble fiber sources (oat hulls; OH, rice hulls; RH, and sunflower hulls; SFH) at 2 levels (2.5 vs. 5%). Each treatment was replicated 6 times. Broilers fed pellets had 32% greater ADG and 3% better feed to gain ratio (F:G) than those fed mash (P ≤ 0.001). The inclusion of the fiber sources improved ADG (P ≤ 0.05) and F:G (P ≤ 0.05). Pelleting increased (P ≤ 0.001) water intake from 6 to 8 d, water-to-feed intake ratio from 18 to 20 d, and moisture content of the excreta at 20 d of age. The inclusion of the insoluble fiber sources increased water intake (P ≤ 0.05) from d 18 to 20 but not from d 6 to 8. Increasing the level of fiber inclusion from 2.5 to 5.0% tended to increase (P = 0.086) moisture content in the excreta at d 20. Pelleting and the inclusion of insoluble fiber sources improved ADG and F:G in broilers fed low-fiber diets, and the improvements observed were more pronounced with pellets than with mash. Growth performance of young broilers improves with the addition of moderate amounts of structural insoluble fiber in the diet, regardless of feed form. The inclusion of OH or SFH into low fiber diets was more beneficial for improving broiler performance than the inclusion of RH.

A total of 1,152 straight-run hatchling Heritage 56M×fast feathering Cobb 500F broiler birds were used to determine Ca, age, and adaptation effects on apparent ileal digestibility of crude protein (AID of CP), amino acids (AID of AA) and phytase efficacy. Twelve treatments with 8 replicates, each were fed from 7 to 9 d (6 birds per replicate), 7 to 21 d (6 birds per replicate) and 19 to 21 d (3 birds per replicate) d of age. Diets were prepared with 3 Ca (0.65, 0.80, and 0.95%) and 2 non-phytate P, (0.20 and 0.40%) concentrations. A 6-phytase was added at 500 or 1,000 FTU/kg to the 0.20% nPP diet at each Ca concentration. The age and adaptation effects were determined by comparing the responses between birds fed from 7 to 9 and 19 to 21 d of age, 19 to 21, and 7 to 21 d of age, respectively. An age effect was observed regardless of Ca, nPP, or phytase concentration, with older birds (19 to 21 d) having greater apparent ileal digestibility (AID) of amino acids (AA) and CP than younger birds (7 to 9 d; P

The effects of feed form and dietary fiber on the development of the gastrointestinal tract (GIT) and nutrient digestibility were studied in broilers at 8 and 21 d of age. The experiment included 14 treatments arranged as a 2 × 7 factorial with 2 feed forms (mash vs. pellet) and 7 diets that consisted in a low fiber diet and 6 extra diets resulting from the combination of 3 insoluble fiber sources [oat hulls (OH), rice hulls, and sunflower hulls] and 2 levels of inclusion (2.5 and 5.0%). Pelleting decreased the relative weight (% BW) of the full GIT, and empty gizzard (P0.001) and the relative length (cm/kg empty BW) of the small intestine and ceca (P0.001) and increased full crop (P0.001) and liver (P0.05) weights. Fiber inclusion increased the empty weight and the fresh digesta content of the gizzard (P0.001) but had limited and inconsistent effects on the weight of the full GIT or the length of the small intestine and ceca. Gizzard pH decreased with mash feeding and fiber inclusion (P0.001). Pelleting decreased ether extract retention (P0.05) but did not affect N retention or AMEn of the diets. Fiber inclusion improved nutrient retention (P0.05 to P0.001) with more pronounced effects with OH than with sunflower hulls or rice hulls inclusion. The AMEn of the diets increased (P0.05) with 2.5% of fiber inclusion but no extra benefits were obtained with a further increase to 5.0%. Starch ileal digestibility increased with mash feeding (P0.001) and fiber supplementation (P0.05). In summary, pelleting increases full crop weight and gizzard pH and decreased full gizzard weight and starch ileal digestibility. Moderate amounts of insoluble fiber, especially OH, increases gizzard weight, reduces gizzard pH, and improves nutrient digestibility in young broilers.

The effects of the inclusion of sunflower hulls (SFH) in the diet on growth performance, coefficient of total tract apparent retention (CTTAR) of nutrients, gastrointestinal tract (GIT) traits and short chain fatty acid (SCFA) concentration in the cecum were studied in chicks from 0 to 21 d of age. Treatments consisted in the combination of two chicken lines (female broilers vs. pullets) and two levels of SFH inclusion (0 vs. 30 g/kg). The control diet contained 11.94 MJ AMEn, 191 g crude protein, 9.8 g digestible Lys and 101 g neutral detergent fiber/kg. The experimental diet included 30 g SFH/kg at the expense (wt:wt) of the control diet. Growth performance was better (P < 0.001) in broilers than in pullets at all ages. Moisture content of the excreta was lower (P < 0.001) in pullets than in broilers at 21 d of age but an opposite effect was observed at 9 d. At 9 d of age, nutrient retention (P < 0.001) and AMEn of the diet (P < 0.01) were higher in broilers than in pullets but at 21 d of age the only difference detected was for N retention (P < 0.001). In absolute terms (g or cm) broilers had heavier (P < 0.001) digestive organs and longer small intestine (SI) and cecum than pullets. In relative terms, however, the GIT (P = 0.062), proventriculus (P < 0.001), gizzard (P < 0.001) and pancreas (P < 0.01) were heavier at 21 d, and the SI and the cecum were longer (P < 0.001) at both ages in pullets. SFH inclusion did not affect growth performance or organ weights at any age but increased the absolute length of the SI and cecum and the AMEn of the diet at 21 d of age (P < 0.05). At 21 d of age, fiber inclusion reduced moisture content of the excreta in broilers but no effects were observed in pullets (P < 0.05 for interaction). The pH of the GIT and the concentration of SCFA in the cecum were not affected by chicken line or SFH inclusion. Villus height and crypt depth were higher (P < 0.001) in broilers than in pullets but were not affected by SFH inclusion. In summary, broilers showed greater growth performance and nutrient retention at 9 d of age and better ileum absorptive capacity at 21 d than pullets. The dilution of the diet with 30 g SFH/kg did not affect chick performance and in fact, improved the AMEn of the diet in both chicken lines at 21 d of age.

SUMMARY One hundred twenty one-day-old female Ross 308 broilers were used to evaluate the impact of including oat hulls (OH), sugar beet pulp (SBP), and pea hulls (PH) at levels of 2.5, 5.0, and 7.5% in the diet on lipid metabolism of broilers from hatch to 21 d of age. The OH, SBP, and PH contained 0.7, 11.6, and 5.1% soluble fiber and 70.6, 47.4, and 49.6% insoluble fiber, respectively. The control diet contained 1.6% crude fiber (6.9% dietary fiber). The fiber sources were included in the experimental diets at the expense (wt/wt) of the control diet. Each treatment was replicated 6 times (a cage with 2 chicks). At 21 d of age, one chick per replicate was slaughtered and plasma lipid metabolites and liver lipid components were determined. At 21 d of age, the inclusion of fiber in the diet tended to reduce total cholesterol (P = 0.06) and to increase HDL cholesterol (P = 0.06) in plasma and reduced lipid components of the liver including total lipids, triglycerides, and total cholesterol (P

In total, 504 female broilers were used to study the effects of inclusion of oat hulls (OH) and sugar beet pulp (SBP) in the diet on growth performance, coefficient of total tract apparent retention (CTTAR) and coefficient of apparent ileal digestibility (CAID) of nutrients from 1 to 18 days (d) of age. A control diet based on rice that contained 69 g dietary fibre (16 g crude fibre)/kg was diluted with 25, 50 and 75 g/kg of either OH or SBP. Each of the seven treatments was replicated six times (a cage with 12 chicks). Growth performance and CTTAR of nutrients were recorded at d 6, 12 and 18 and the CAID of organic matter and crude protein were determined at d 18. From d 1 to 18, fibre inclusion did not affect feed intake or body weight gain of the birds. However, feed conversion ratio was improved quadratically (Q) with OH (P

The effects of inclusion of oat hulls (OH) and sugar beet pulp (SBP) in the diet on the development of the gastrointestinal tract (GIT) were studied in broilers from 1 to 18 days (d) of age. A control diet based on rice that contained 16 g crude fibre (69 g dietary fibre)/kg was diluted with 25, 50 and 75 g of either OH or SBP/kg. Each of the seven treatments was replicated six times (a cage with 12 chicks). The weight of the digestive organs and the pH of the digesta contents were recorded at d 6, 12 and 18, and the jejunal morphology at d 12 and 18. The inclusion of a fibre source in the diet affected in different ways the development of the organs of the GIT. The relative weight of the GIT with digesta contents (g/kg body weight, BW) increased linearly (L; P≤0.001) as the level of fibre in the diet increased. The weight of the pancreas increased (L; P≤0.01 at d 6 and 12, and P

The effects of including 3% sunflower hulls (SFH) in the diet on growth performance, nutrient retention (TTAR), and gastrointestinal tract (GIT) traits were studied in chicks from zero to 21 d of age. Four treatments that resulted from the combination of 2 chicken lines (female broilers vs. brown pullets) and 2 levels of SFH (zero vs. 3%) were used. The control diet contained 2,980 kcal AMEn/kg, 1.25% digestible Lys, and 8.7% neutral detergent fiber. The experimental diet included 3% SFH at the expense (wt:wt) of the whole diet. Growth performance, TTAR of nutrients, and the AMEn of the diet were greater (P = 0.097 to P 0.001) in broilers than in pullets. In absolute terms, all the organs of the GIT were heavier (P 0.001) and the small intestine and cecum were longer (P 0.001) in broilers than in pullets. At 21 d of age, however, the relative weight (% BW) of all the organs of the GIT (P 0.001) and the relative length (cm/kg BW) of the small intestine and cecum (P 0.01) were greater in pullets. Gizzard pH (P 0.001), total short chain fatty acids concentration in the cecum (P = 0.098), and villus height (P 0.001) and crypt depth (P 0.05) of the ileum mucosa were higher in broilers. The inclusion of SFH increased (P 0.05) the AMEn content of the diet but did not affect bird performance, moisture content of the excreta, or the concentration and profile of fatty acids in the cecum. Dietary SFH increased gizzard weight and reduced gizzard pH (P 0.001) at both ages. In conclusion, broilers had better growth performance, nutrient retention, and ileum absorptive capacity than pullets. The inclusion of 3% SFH at the expense of the control diet did not have any negative effect on chick performance and, in fact, increased gizzard weight, reduced gizzard pH, and improved the energy content of the diet.

The effects of including 3% sunflower hulls (SFH) in the diet on growth performance, nutrient retention (TTAR), and gastrointestinal tract (GIT) traits were studied in chicks from zero to 21 d of age. Four treatments that resulted from the combination of 2 chicken lines (female broilers vs. brown pullets) and 2 levels of SFH (zero vs. 3%) were used. The control diet contained 2,980 kcal AMEn/kg, 1.25% digestible Lys, and 8.7% neutral detergent fiber. The experimental diet included 3% SFH at the expense (wt:wt) of the whole diet. Growth performance, TTAR of nutrients, and the AMEn of the diet were greater (P = 0.097 to P < 0.001) in broilers than in pullets. In absolute terms, all the organs of the GIT were heavier (P < 0.001) and the small intestine and cecum were longer (P < 0.001) in broilers than in pullets. At 21 d of age, however, the relative weight (% BW) of all the organs of the GIT (P < 0.001) and the relative length (cm/kg BW) of the small intestine and cecum (P < 0.01) were greater in pullets. Gizzard pH (P < 0.001), total short chain fatty acids concentration in the cecum (P = 0.098), and villus height (P < 0.001) and crypt depth (P < 0.05) of the ileum mucosa were higher in broilers. The inclusion of SFH increased (P < 0.05) the AMEn content of the diet but did not affect bird performance, moisture content of the excreta, or the concentration and profile of fatty acids in the cecum. Dietary SFH increased gizzard weight and reduced gizzard pH (P < 0.001) at both ages. In conclusion, broilers had better growth performance, nutrient retention, and ileum absorptive capacity than pullets. The inclusion of 3% SFH at the expense of the control diet did not have any negative effect on chick performance and, in fact, increased gizzard weight, reduced gizzard pH, and improved the energy content of the diet.

SUMMARY The ban on the use of antibiotics in feeds as growth promoters in many countries throughout the world has increased the incidence of enteric disorders in poultry. Natural additives, inclusion of whole cereals, feeding coarse mash diets, and increasing the level of fiber in the diets have been explored as nutritional strategies to reduce the incidence of the problem. Traditionally, dietary fiber has been considered a diluent of the diet and, often, an antinutritional factor. However, moderate amounts of fiber might improve the development of organs, enzyme production, and nutrient digestibility in poultry. Some of these effects are a consequence of better gizzard function, with an increase in gastroduodenal refluxes that facilitate the contact between nutrients and digestive enzymes. These effects often result in improved growth and animal health, but the potential benefits depend to a great extent on the physicochemical characteristics of the fiber source. In conclusion, poultry require a minimal amount of fiber in the diet for proper functioning of the digestive organs. The response to fiber inclusion depends on the source and level of dietary fiber and the characteristics of the diet as well as on the physiological status and health of the bird. In particular, the inclusion in the diet of moderate amounts of coarse, insoluble fiber sources, such as oat hulls, at levels between 2 and 3% usually improves the growth performance of broilers fed low-fiber diets.

A total of 864 brown-egg laying pullets was used to study the effects of the main cereal of the diet (500 g maize or wheat/kg) and particle size of the cereal (hammer milled to pass through a 6-, 8-, and 10-mm screen) on growth performance and digestive traits from 1 to 120 d of age. Each of the six treatments was replicated six times (24 pullets per replicate). Type of cereal did not affect pullet performance at any age. From 1 to 45 d of age, body weight (BW) gain was increased (P

The effects of the inclusion of additional fibre in the diet on growth performance and digestive traits were studied in broilers from 1 to 42 days of age. There were three diets: a control diet based on rice, soy protein concentrate and fish meal with a crude fibre content of 15 g/kg and two additional diets that included 30 g of either oat hulls (OH) or sugar beet pulp (SBP)/kg. Nitrogen retention and the coefficients of total tract apparent digestibility (CTTAD) of nutrients were determined at 32 days and the relative weight (RW; g/kg body weight) of the gastrointestinal tract and the yield in primal cuts of the carcass were measured at 42 days of age. In addition, growth performance was measured from 1 to 42 days. For the entire experimental period, broilers fed OH had higher (P≤0.01) body weight gain (BWG) and better (P≤0.01) feed to gain ratio (FCR) than broilers fed SBP or the control diet. From 1 to 10 days of age, OH inclusion improved (P≤0.01) BWG and FCR as compared with the control diet. Also, SBP improved FCR in this period but the effects disappeared with age. In fact, from 25 to 42 days of age, SBP inclusion reduced (P≤0.05) feed intake with respect to the control diet and feed intake (P≤0.05) and BWG (P≤0.001) with respect to the OH diet. The RW of the gastrointestinal tract was higher (P≤0.05) with the SBP than with the control diet with the OH diet being intermediate. Also, the RW of the gizzard increased (P≤0.001) with dietary fibre inclusion and the effects were more pronounced (P≤0.05) with OH than with SBP. The digesta content of the gizzard increased (P≤0.001) with fibre inclusion and the effects were more pronounced with SBP than with OH. Leg quarters and breast yields were not affected by dietary treatment. Fibre inclusion increased (P≤0.01) the CTTAD of all nutrients and the metabolisable energy content of the diet. The improvement in CTTAD observed for dry matter and nitrogen was more pronounced (P≤0.01) for OH than for SBP. We conclude that the inclusion of OH in the diet improves growth performance at all ages in broilers fed low fibre diets. Also, SBP inclusion improves growth performance from 1 to 10 days of age but not thereafter. The CTTAD of nutrients were improved by fibre inclusion and the benefits were more pronounced with OH than with SBP.

The influence of soybean meal (SBM) source and total Lys content of the diet on performance and total tract apparent retention of nutrients was evaluated in broilers from 1 to 36 d of age. There were 6 treatments arranged factorially with 2 sources of SBM [regular SBM with 46.3% CP (R-SBM) and high-protein SBM with 48.6% CP (HP-SBM)] and 3 Lys:AME(n) ratios (Lys:ME; 380, 415, and 450 mg of total Lys:1,000 kcal of AME(n) from 1 to 21 d; and 312, 338, and 364 mg of total Lys:1,000 kcal of AME(n) from 22 to 36 d of age). From 1 to 36 d of age, broilers fed the HP-SBM diets had higher ADG and better feed:gain ratio (F:G) than broilers fed the R-SBM diets (P < or = 0.001). Both ADG and F:G improved (P < or = 0.05) with increases in the Lys:ME ratio. From 1 to 21 d of age, ADG and F:G (P < or = 0.001) were improved when the Lys:ME ratio increased and the benefits were more pronounced with the diets based on R-SBM. From 22 to 36 d of age, increasing the Lys:ME ratio from 312 to 338 increased ADG (P < or = 0.05) and F:G (P < or = 0.01), but no further improvements were observed when the ratio was increased to 364. The total tract apparent retention of DM and gross energy of the diets were higher (P < or = 0.05) for the HP-SBM than for the R-SBM diets. An increase in the Lys:ME ratio reduced organic matter and N retention (P < or = 0.05). The improvements in growth performance and nutrient retention observed in broilers fed the HP-SBM diets with respect to those fed the R-SBM are consistent with a better availability of nutrients of the high-protein meal. In addition, the results indicate that Lys requirements of broilers are at least, 30, 20, and 8% higher from 1 to 10, 10 to 21, and 21 to 36 d of age, respectively, than current NRC recommendations.

The influence of fiber source and dietary fat level on digestive traits and productive performance was studied in broilers from 1 to 21 d of age. There were 6 treatments arranged factorially with 3 sources of fiber (none; 3% oat hulls, OH; and 3% sugar beet pulp, SBP) and 2 fat sources (5% soybean oil, SO; and 5% yellow grease, YG). Each treatment was replicated 6 times and the experimental unit was a cage with 18 broilers. Fiber inclusion improved BW gain (P < or = 0.05) and feed:gain ratio (P < or = 0.001) and increased total tract apparent retention (TTAR) of all nutrients measured (P < or = 0.001). The increases observed in TTAR of nitrogen and ether extract and on AME(n) of the diet were more pronounced with OH than with SBP. The increases in nutrient digestibility with OH inclusion were higher at excreta than at ileal level and in fact, SBP inclusion reduced the apparent ileal digestibility of most nutrients. The relative weight (%) of the gizzard was increased (P < or = 0.001) and the pH of its contents was reduced (P < or = 0.001) when additional fiber was included in the diet. The TTAR of nutrients was higher for the SO than for the YG diets (P < or = 0.001). Also, the increases in ether extract digestibility (P < or = 0.05) and AME(n) (P < or = 0.05) of the diet with fiber inclusion were more pronounced with the YG than with the SO. Therefore, the inclusion of moderate amounts of fiber in the diet might improve performance and nutrient digestibility in young chicks, especially when saturated fats are used.

The effects of different sources of dietary fibre on gastrointestinal tract (GIT) development and digesta pH were studied in 25-day-old broilers. There were four diets: a control diet low in fibre content (37.3 g neutral detergent fibre and 16.0 g acid detergent fibre/kg) and three additional diets in which 30 g/kg of cellulose (CEL), sugar beet pulp (SBP) or oat hulls (OH) were included at the expenses of sepiolite (a complex magnesium silicate clay). The relative weight (RW, %BW) of the GIT was greater with the SBP – than with the CEL – and the control diets. Also, gizzard RW was higher with the diet containing OH than with the diet containing CEL or the control diets, with the SBP diet being intermediate (P≤0.001). Fibre inclusion modified the pH of the GIT (P≤0.05) but the effects depended on the type of fibre. Crop pH was higher and proventriculus pH lower with SBP than with the other diets. However, gizzard pH was reduced with SBP and OH but not with CEL (P≤0.05). The pH of the digesta of the duodenum was similar for all diets but that of the jejunum, Meckel's diverticulum and ileum increased with SBP and decreased with CEL inclusion (P≤0.05). We concluded that dietary fibre affects the development and pH value of the different segments of GIT and that the effects differ according to the physico-chemical characteristics of the source of fibre used.

An experiment was conducted to study the effects of type of cereal (60% corn or 60% rice), heat processing of the cereal (raw or steam-cooked), and fiber source (control without hulls, 3% oat hulls, and 3% soy hulls) on gizzard pH and total tract apparent retention (TTAR) of nutrients in broilers at different ages. There were 12 treatments arranged factorially (2x2x3) and 6 replicates (8 chicks) per treatment. The 2 basal diets were based on soy protein concentrate and fish meal and had a neutral detergent fiber content of 3.5% for the rice and 7.3% for the corn diet. Gizzard pH was lower at 13 d than at 8 or 20 d of age (P

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 P P P

A trial was conducted to study the influence of cooking–flaking (C-F) of maize and enzyme supplementation (ES) of the diet on mucosa morphometry, digestive organ weight, dietary component digestibility and growth performance of broilers from 1 to 21 days of age. There were 4 treatments arranged factorially with 2 heat processings of maize (raw and C-F) and 2 levels (0 and 500 mg/kg) of an enzyme complex with xylanase, protease and α-amylase activity. Dietary treatment did not affect any productive trait from 1 to 21 days of age. However, from 1 to 4 days of age, body weight gain (P

A trial was conducted to determine the coefficient of ileal apparent digestibility (CIAD) and ileal true digestibility (CITD) of amino acids of raw pea protein concentrate (PPC), soya protein concentrate (SPC), soya bean meal (SBM) and fullfat soya bean (FFSB) in 21-day-old broilers. Four diets were formulated based on maize starch and sucrose and with the test ingredient as the unique source of dietary protein (200 g/kg). In addition, a nitrogen free diet was formulated to estimate the basal ileal endogenous losses of amino acids. Chicks were fed a commercial maize-SBM diet from 1 to 17 days and then, their respective experimental diets from 18 to 21 days of age. All feeds were offered ad libitum in mash form and each treatment was replicated 6 times. Chicks fed SPC and SBM had higher CIAD of arginine, methionine and valine than chicks fed PPC (P

A total of 960 Lohmann Brown laying hens were used to study the effects of the main cereal of the diet and geometric mean diameter (GMD) of the cereal on productive performance and egg quality from 20 to 48 wk of age. The experiment was a completely randomized design with 6 treatments arranged factorially with 2 cereals (dent corn vs. durum wheat) and 3 GMD of the cereal (hammer-milled to pass through 6-, 8-, or 10-mm screens). Each treatment was replicated 8 times (20 hens per replicate). All diets were formulated to be isonutritive and contained 50% of either corn or wheat. Productive traits were recorded every 4 wk and egg quality was measured at 48 wk of age. The only significant effect detected was for feed intake (P < 0.05) that was greater for hens fed coarse-ground cereals (10-mm screen) than for hens fed medium and fine-ground cereals (8- or 6-mm screen). None of the egg quality parameters studied were influenced by dietary treatment. We conclude that neither type of cereal nor GMD affected productive performance or egg quality of young brown hens, except for feed intake that increased with the coarser particle size.

The current study was conducted to evaluate the impacts of using tibia ash percentage or ash weight as the response criteria on estimated phytase relative equivalence. Straight run broilers were fed treatment (Trt) diets from 7 to 21 d age (6 birds/pen, 8 pens/Trt). The corn-soy based Trt were formulated to contain 0.80% Ca and 4 non-phytate phosphorus (nPP) concentrations (0.20, 0.27, 0.34, and 0.40%). Monocalcium phosphate was the inorganic phosphate source added to achieve 4 different dietary nPP concentrations and against which the nPP relative equivalence of phytase was determined. A 6-phytase (Danisco Animal Nutrition, DuPont Industrial Biosciences, Marlborough, UK) was added at 500 or 1,000 phytase unit ( FTU: )/kg to the 0.20% nPP diet resulting 6 total Trts. Tibia ash was determined at 21 d age. Phytase fed at 500 or 1,000 FTU/kg increased tibia ash weight and ash percentage compared to that of birds fed 0.20% nPP diet without phytase (P

A study was done to determine whether broilers can regulate Ca intake when limestone is provided separately or mixed with a crumbled feed of variable Ca and P content, and the influence of this on performance and apparent ileal digestibility (AID) of Ca and P (AIDP). Twelve crumbled diets were fed from 10 to 20 d of age (8 replicates, 8 broilers/replicate). Diets A to D contained 0.28% nonphytate P (nPP) and 0.27, 0.51, 0.77, and 1.02% Ca, respectively. Diets E to H contained 0.48% nPP and 0.41, 0.51, 0.77, and 1.02% Ca, respectively. A large particle size limestone was mixed manually to the crumbled diet on a daily basis to achieve 1.02% total Ca in diets A to H. Diets I to L had the same Ca and nPP as diets A to D, but limestone was provided in a separate feeder to assess spatial importance of limestone supply. Limestone consumption, provided in a separate feeder, decreased as Ca concentration increased in the crumble diet (P < 0.05). Calcium intake increased as Ca concentration in crumbled diets increased (P < 0.05). Increased tibia ash and decreased AIDP were observed as Ca intake increased (P < 0.05). When limestone was added to diets containing 0.28% nPP postcrumble, Ca intake (6.38 g/bird), tibia ash (717 mg/bone), and AIDP (39.78%) were not affected by crumbled diet Ca concentration or consumed Ca. Broilers fed diets containing 0.48% nPP and limestone mixed with the crumble, Ca intake changed (5.96, 6.93, 6.59, and 6.04 g/bird for crumble diet with 0.41, 0.51, 0.77, and 1.02% Ca, respectively). Increasing Ca concentration in the crumble from 0.41 to 1.02% resulted in greater tibia ash (875 mg/bone) but lower AIDP (P < 0.05), although Ca intake was similar. In conclusion, when large particle size limestone was provided ad libitum, the ability of broilers to select for Ca was not sufficient to meet their requirement when crumble Ca was less than 0.77%. The AIDP was highest in birds fed the 0.27% Ca concentration diet.

The effects of inclusion of pea hulls (PH) in the diet on growth performance, development of the gastrointestinal tract and nutrient retention were studied in broilers from 1 to 18. d of age. There were a control diet based on low fibre ingredients (69.3 total dietary fibre (16.1. g crude fibre/kg)) and three additional diets that resulted from the dilution of the basal diet with 25, 50 and 75. g PH/kg (81.2, 93.2, and 105.1. g total dietary fibre/kg diet, respectively). Each treatment was replicated six times and the experimental unit was a cage with 12 chicks. Growth performance, development of the gastrointestinal tract and the coefficients of total tract apparent retention (CTTAR) of nutrients were recorded at 6, 12 and 18. d of age. In addition, jejunal morphology was measured at 12 and 18. d and the coefficients of apparent ileal digestibility (CAID) of nutrients at 18. d of age. Pea hulls inclusion affected all the parameters studied. The inclusion of 25 and 50. g PH/kg diet improved growth performance as compared to the control diet. The relative weight (g/kg body weight) of proventriculus (P≤0.01), gizzard (P≤0.001) and ceca (P≤0.05) increased linearly as the level of PH in the diet increased. The inclusion of PH affected quadratically (P≤0.01) villus height:crypt depth ratio with the highest value shown at 25. g PH/kg. In general, the CTTAR and CAID of nutrients increased linearly and quadratically (P≤0.05) with increasing levels of PH, showing maximum values with PH level between 25 and 50. g/kg diet. We conclude that the size of the digestive organs increases with increasing levels of PH in the diet. In general, the best performance and nutrient digestibility values were observed with levels of PH within the range of 25 and 50. g/kg. Therefore, young broilers have a requirement for a minimum amount of dietary fibre. When pea hulls are used as a source of fibre, the level of total dietary fibre required for optimal performance is within the range of 81.2-93.2. g/kg diet (25.6-35.0. g crude fibre/kg diet). An excess of total dietary fibre (above 93.2. g/kg diet) might reduce nutrient digestibility and growth performance to values similar to those observed with the control diet. © 2011 Elsevier B.V.

A trial was conducted to study the effects of type and particle size of dietary fiber on growth performance and digestive traits of broilers from 1 to 21 d of age. There was a negative control diet with 1.54% crude fiber, a positive control diet that included 3% cellulose (CEL), and 4 additional diets arranged factorially that included 3% oat hulls (OH) or sugar beet pulp (SBP) ground through a 0.5- or a 2.0-mm screen. For the entire experimental period, fiber inclusion improved BW gain (P≤0.01) and feed conversion ratio (P≤0.001), but particle size of the fiber source did not affect performance. The relative weight of the gizzard was higher (P≤0.001) with OH and SBP than with CEL or the control diet. Also, gizzard weight decreased (P≤0.001) with a reduction in particle size of the fiber source. Fiber inclusion increased HCl concentration and reduced gizzard pH (P≤0.01), and the effects were more noticeable with OH and SBP than with CEL. Fiber inclusion increased total tract apparent retention of nitrogen (P≤0.001) and soluble ash (P≤0.001) as well as the AMEn of the diet (P≤0.001). All of these effects were in general more pronounced with OH than with CEL, with SBP being intermediate. A reduction in particle size of the OH and SBP improved total tract apparent retention of DM (P≤0.001), nitrogen (P≤0.05), and soluble ash (P≤0.01) as well as the AMEn of the diet (P≤0.05). It is concluded that additional OH and SBP improves gizzard weight and growth performance in young chicks fed low-fiber diets and that the effects are more pronounced with OH than with CEL. Particle size of OH and SBP does not affect broiler performance, but coarse grinding increases gizzard development and reduces nutrient digestibility in young birds.

A total of 1152 one-day-old Hy-Line Brown pullets were used to study the influence of energy content of the diet and feed form on productive performance and digestive tract traits. From 1 to 45 days (d) of age, there were six diets arranged factorially with three Apparent Metabolizable Energy (AMEn) concentrations (low, medium and high) and two feed forms (mash and pellets). From 45 to 120 d all diets were fed in mash form and therefore, the only difference was the energy content. Each of the 6 treatments was replicated 8 times and the experimental unit was formed by 24 pullets housed in 2 adjacent cages. For the entire experiment, body weight (BW) gain and feed to gain ratio improved as the AMEn of the diet increased (P

The coefficient of apparent ileal digestibility (CAID) of DM, gross energy (GE), N, and amino acids (AA) of 6 soybean meal (SBM) samples were compared in 21-d-old broilers. In addition, the digestibility of DM and N of diets that contained these SBM were tested in vitro. Four of the SBM were of South American origin, had a CP content varying from 45.2 to 47.2% and a trypsin inhibitor activity (TIA) varying from 4.1 to 6.5 mg/g, and were collected from local traders. The other 2 SBM were from US origin; one was a branded product with 48.6% CP and 1.8 mg of TIA/g and the other was obtained from soybeans of US origin that were dehulled and processed in Spain (50.6% CP and 2.4 mg of TIA/g). The experimental design was completely randomized with 6 diets and 6 replicates per treatment. Chicks were fed a commercial diet from 1 to 16 d of age and then their respective experimental diets for 5 d. The diets were based on sucrose and corn starch, with the SBM tested as the only source of protein. At 21 d of age, digesta was collected from the distal ileum and the CAID of nutrients was determined using celite as an indigestible marker. Diets that included the 2 SBM with the greatest CP content had greater CAID of DM (P

A total of 1,152 Lohmann Brown laying hens were used to study the influence of level (3.5 and 4.0%) and source (coded FIN, COA, and OYS) of Ca in the diet on productive performance and egg quality from 58 to 73 wk of age. The FIN diet contained all the Ca carbonate as fine limestone (LIM). In the COA and OYS diets, 40% of the fine LIM was substituted with either coarse LIM or oyster shell. Each treatment was replicated 8 times (24 hens). Productive performance and egg quality traits were recorded every 4 wk, and tibia characteristics and shell quality traits were determined at 73 wk of age. An increase in Ca intake from 4.08 to 4.64 g/hen per day improved egg production (71.2 vs. 74.9%; P < 0.001), egg mass (49.0 vs. 51.4 g; P < 0.05), and feed conversion ratio (2.43 vs. 2.30 kg of feed/kg of egg; P < 0.001). In addition, an increase in Ca intake improved shell weight (9.98 vs. 10.20%; P < 0.05), shell thickness (0.342 vs. 0.351 mm; P < 0.01), and shell density (82.0 vs. 83.8 mg/cm2; P < 0.001). Calcium source had no effect on productive performance, tibia characteristics, or egg quality except for shell density, which was greater for hens fed COA than for hens fed FIN, with hens fed OYS being intermediate (81.9 vs. 84.0 vs. 82.7 mg/cm2, respectively; P < 0.05). It was concluded that Brown egg-laying hens in the late phase of production require more than 3.5% Ca in the diet (4.08 g of Ca/hen per day) and that the substitution of 40% of fine LIM with COA or OYS does not affect productive performance and has little impact on shell quality and tibia characteristics.

We studied the influence of the cereal (corn and rice), heat processing (HP) of the cereal (raw and steam cooking), and fiber inclusion (none; 3% oat hulls, OH; and 3% soy hulls, SH) in low-fiber diets on the development and pH of the digestive tract in broilers. There were 12 treatments arranged factorially and 3 replicates (a cage with 12 chicks) per treatment. Digestive traits were measured at 1, 5, 9, 15, and 22 d of age, and digesta pH was determined at 22 d of age. The relative weight (% BW) of proventriculus and gizzard was greater in chicks fed corn than in chicks fed rice (P < or = 0.01). Heat processing had little effect on relative weight (RW) of the digestive organs. An interaction between cereal and HP of the cereal was detected for the gizzard and the liver; HP of corn reduced RW of the gizzard and increased that of the liver, but no effect was observed with HP of rice. The RW of the proventriculus was increased by SH inclusion (P < or = 0.05), whereas the RW of the gizzard was increased by OH inclusion (P < or = 0.001). Also, SH inclusion increased gizzard digesta (P < or = 0.01) and moisture (P < or = 0.001) content. Dietary treatment did not affect relative length (cm/kg of empty BW) of the intestines. Feeding rice tended to increase gizzard digesta pH (P = 0.081) but reduced that of the intestines (P < or = 0.001). Neither HP of the cereal nor hull inclusion affected pH of the digestive tract. We conclude that the RW of the proventriculus and gizzard is reduced by feeding rice and increased by hull inclusion. Dietary treatment had little effect on the weight and relative length of the intestines. Chicks might require a minimal amount of fiber in the diet to stimulate the development of the upper gastrointestinal tract.

Two trials were conducted to study the effect of reducing the methionine (MET, 0.36 vs. 0.31%), linoleic acid (LIN, 1.60 vs. 1.12%), and supplemental fat (SFAT, 3.0 vs. 1.1%) content of isoenergetic diets on the productive performance and egg quality of brown laying hens late in the production cycle. The 8 treatments were arranged factorially (2 x 2 x 2), with 6 replicates of 20 hens per treatment (Hy-Line, from 59 to 70 wk of age in trial 1, and Lohmann, from 56 to 75 wk of age in trial 2). Except for SFAT content, dietary treatment had little effect on laying hen performance and egg quality. The only effect of a reduction in MET content on hen performance was the decrease in the percentage of large and extra large eggs (79.8 vs. 85.9%; P < 0.05) from 60 to 67 wk of age in trial 2. A decrease in the level of SFAT reduced egg production (79.3 vs. 77.0%; P < 0.05), egg weight (66.3 vs. 64.9 g; P < 0.001), egg mass (52.5 vs. 49.8 g/d; P < 0.001), feed conversion ratio (2.26 vs. 2.36 kg of feed/kg of eggs; P < 0.001), and percentage of extra large eggs (13.1 vs. 8.2%; P < 0.05) in trial 1, but no significant differences were detected in trial 2. Reducing the LIN content of the diet from 1.60 to 1.12% did not affect any trait in either of the 2 trials. We conclude that reducing the level of SFAT from 3.0 to 1.1% might decrease productivity and the percentage of extra large eggs. However, a reduction in the MET level from 0.36 to 0.31% and in LIN from 1.60 to 1.12% did not affect any trait in hens late in the production cycle. Eggshell quality was not affected by any of the dietary treatments.

We studied the influence of cereal, heat processing of the cereal, and inclusion of additional fiber in the diet on the productive performance and digestive traits of broilers from 1 to 21 d of age. Twelve treatments were arranged factorially, with 2 cereals (corn and rice), 2 heat-processing treatments of the cereals (raw and cooked), and 3 sources of fiber (none, 3% oat hulls, and 3% soy hulls). Each treatment was replicated 6 (trial 1) or 3 (trial 2) times. Growth traits were recorded in both trials; digestive traits were measured in trial 1, and total tract apparent retention (TTAR) of nutrients was determined in trial 2. Feeding rice improved TTAR of all nutrients and feed conversion from 1 to 21 d of age (P