Effects of thermal processing (toasting or extrusion) of untoasted soybean meal on growth performance, apparent ileal nutrient digestibilities, and chyme characteristics were studied in broiler chicks fed diets with soybean meal as the main protein source. Effects of increasing shear forces during extrusion as well as enzyme treatments (protease and carbohydrase) were also studied. When compared with toasting, extrusion significantly improved feed conversion ratio (1.56 vs 1.62) and apparent ileal digestibilities of CP and nonstarch polysaccharides (87.5 vs 82.2% and 26.7 vs 11.4%, respectively). Enzyme treatment improved apparent ileal digestibility of CP and nonstarch polysaccharide compared with no enzyme treatment (85.2 vs 83.7% and 20.6 vs 14.5%, respectively); however, enzyme treatments did not result in a better growth performance of the chicks. Among the enzyme treatments, no differences were found in growth performance and apparent ileal CP digestibility, whereas the carbohydrase significantly improved apparent ileal nonstarch polysaccharide digestibility compared with the other enzyme treatments. Extrusion of SBM at the highest shear level caused a significant increase in the water-holding capacity, chyme viscosity, and concentration of soluble nonstarch polysaccharides in the chyme compared with extrusion of SBM at lower shear levels. The increase in chyme viscosity did not affect growth performance, nor did it influence apparent ileal nutrient digestibilities.

An in vivo experiment was conducted to study the potential prebiotic effects of mushroom and herb polysaccharide extracts, Lentinus edodes extract (LenE), Tremella fuciformis extract, and Astragalus membranaceus Radix extract, on chicken growth and the cecal microbial ecosystem, as compared with the antibiotic Apramycin (APR). This investigation was carried out in terms of a dose-response study. The chickens were naturally infected with avian Mycoplasma gallisepticum prior to the experiment. The BW gain, cecal pH, viscosity, and predominant microbial populations were measured 1 wk after the extract and APR treatments. The extracts and APR significantly stimulated growth of the chickens infected with avian Mycoplasma gallisepticum. The average BW gain of the groups fed with the extracts was significantly lower than that of the antibiotic group. The extracts had no significant effect on cecal pH. However, cecal viscosity and microbial populations were significantly affected by feeding extracts and antibiotic. In contrast to APR, the extracts stimulated the number of the potentially beneficial bacteria (bifidobacteria and lactobacilli), while reducing the number of the potentially harmful bacteria (Bacteroides spp. and Escherichia coli). Of the 3 extracts, LenE was associated with the most cecal bifidobacteria and lactobacilli. With each increase in the LenE dose, birds tended to have higher BW gain and total aerobe and anaerobe counts. Numbers of predominant cecal bacteria, in particular, E. coli, bifidobacteria, and lactobacilli, were significantly increased with increases in the LenE dose. It would seem that these specific mushroom and herb polysaccharide extracts hold some promise as potential modifiers of intestinal microbiota in diseased chickens.

Heat stress can induce hyperthermia in poultry. A reduction in heat load can be achieved by increasing the possibilities for dissipation, decreasing the level of heat production or by changing the thermal production pattern within a day. Strategies to reduce the negative effects of heat stress can be based on a specific feeding strategy, such as restricted feeding. Feed that is offered long enough before a hot period can ameliorate the harmful effects of high temperature. Another strategy may be to use choice feeding from different feed ingredients, rich in protein or in energy. With such self-selection, the chicken may adjust its intake of individual components, allowing the bird to optimise the heat load associated with the metabolism of the ingested nutrients. Additional promising strategies involve offering a choice between feeds with a different feed particle size or structure. A large particle size contributes to the development of the gastro-intestinal tract (GIT), especially the gizzard and the caeca. A large gizzard will maximize the grinding process and potentially ease digestion down the GIT, thereby reducing heat production associated with digestive processing. Also wet feeding may be profitable under heat stress conditions as well. Feeding wet diets may facilitate an increased water intake and larger particle sizes can limit water excretion in droppings, resulting in more water being available for evaporation during panting, hence cooling the bird. In conclusion, these feeding strategies may help to reduce heat production peaks, facilitate evaporative activity and/or decreases the heat load, resulting in beneficial effects on performance and health of the bird kept in more tropical areas worldwide.

We investigated the effects of polysaccharide extracts from 2 mushrooms, Lentinus edodes (LenE) and Tremella fuciformis (TreE), and an herb, Astragalus membranaceus (AstE), on cellular and humoral immune responses of Eimeria tenella-infected chickens. A total of 150 broiler chicks were assigned to 5 treatment groups: 3 groups were infected with E. tenella and fed with extracts (LenE, TreE, and AstE), and 2 control groups were infected with or without E. tenella. The 3 extracts were given at the level of 1 g/kg of the diet from 8 to 14 d of age. Specific systemic and cecum mucosal antibody production, proliferation of splenocytes, and peripheral T and B lymphocytes were measured during the 3 wk following Eimeria infection. A significantly higher production of specific IgA, IgM (at d 14 and 21 postinfection), and IgG (at d 21 postinfection) were detected in the Eimeria-infected groups fed with the extracts than in the infected group not fed with the extracts. Of the 3 extracts, TreE stimulated a slightly higher production of specific IgM (P = 0.052), and a significantly higher IgG production at 21 d postinfection. The cecal antibody production showed a similar trend to that of serum antibodies. The overall mean levels of cecal-specific IgA and IgG of the groups fed with extracts were significantly higher at 14 and 21 d postinfection compared with the group not fed with extracts. Of the 3 extracts, the AstE-fed group showed the highest IgG production at d 7 postinfection. Both TreE- and LenE-fed groups had significantly higher IgM and IgG levels compared with the AstE group at d 21 postinfection. The extract-fed groups also showed a significantly higher antigen-specific proliferation of splenocytes at 14 and 21 d postinfection compared with the group not fed with the extracts. The overall mean of erythrocyte rosette-forming cells (ERFC %) (at d 14 and 21) and erythrocyte-antibody-complement cells (EAC %) (at d 14) of the groups fed with the extracts was significantly higher compared with the group not fed the extracts. It is concluded from this study that supplementation with mushroom and herb extracts resulted in enhancement of both cellular and humoral immune responses in E. tenella-infected chickens.

An experiment with 288 male (Ross 308) 1-d-old broilers was conducted to test the hypothesis that a coarse diet supplemented with butyric acid (BA) and fermentable carbohydrates (FC) improves performance of broilers with a poorly digestible protein source. The interaction effects of diet structure (fine or coarse), FC supplementation (with or without), and BA supplementation (with or without) in a poorly digestible diet based on rapeseed meal (RSM) were tested in a factorial arrangement of 8 (2 × 2 × 2) dietary treatments. The coarseness of the diet affected feed intake (FI) (P < 0.001), BW gain (P = 0.001), and the feed conversion ratio (FCR) (P = 0.001) positively. Broilers fed the coarse diets had, on average, 14% heavier gizzards and 11, 7, 5, and 6% lower relative empty weights of the crop, duodenum, jejunum, and ileum, respectively, compared with those fed the fine diets. Dietary coarseness resulted in, on average, 6% greater ileal protein digestibility, 20% lower gizzard pH, 19% greater villus height, 18% lower crypt depth, and 23% reduced cecal branched chain fatty acids (BCFA) compared with chickens fed the fine diets. Broilers fed BA-supplemented diets had an improved FCR (P = 0.004) and decreased crypt depth (P < 0.001) compared with those fed diets without BA. Fermentable carbohydrate supplementation did not influence growth performance, gut development, or contents of total BCFA and total biogenic amines in the cecal digesta (P > 0.05). Supplementation with FC, however, decreased the cecal concentration of spermine by approximately 31% compared with broilers fed diets without FC (P = 0.002). In conclusion, feeding a coarse diet supplemented with BA improved performance of broilers fed a diet containing a poorly digestible protein source. The negative effects of a poorly digestible protein source can thus be partly counterbalanced by coarse grinding and BA supplementation in the diet.

Eggs contribute for about 4% to the daily dioxin intake of humans. Research among layer farms in the Netherlands and other EU countries has shown that organic eggs contain more dioxin than conventional ones and that a significant number of organic farms produce eggs with a dioxin content that exceeds the EU standard. The hens' intake of dioxins from various sources leads to an increase in the dioxin content of organic eggs. These sources include plants, feed, soil, worms and insects, and compared with hens on conventional and free-range farms, organic hens make more use of these sources due to better access to the outdoor run. Plants appear to be relatively unimportant as a source of dioxins. Also commercial organic feed generally has very low dioxin contents, but not much is known about non-commercial feed. Consumption of worms and insects and particularly ingestion of soil are important causes of high dioxin levels in eggs. Management interventions, like a reduction of the time the hens spend outside, may decrease the dioxin levels in organic eggs but at the same time may interfere with the image of the organic production system.

An experiment with 210 male (Ross 308) 1-d-old broilers was conducted to test the hypothesis that a coarse diet improves performance of broilers fed a poorly digestible protein source. A highly digestible diet based on soybean meal was gradually replaced by a low digestible diet based on rapeseed meal (RSM) in 5 steps (RSM-0%, RSM-25%, RSM-50%, RSM-75%, and RSM-100%). Two diet structures (fine and coarse) were used as an additional factor. These 2 factors and their interactions were tested at different ages in a factorial arrangement with 10 dietary treatments. An increase in indigestible dietary protein negatively affected feed intake (P = 0.003), BW gain (P = 0.008), and feed conversion ratio (P = 0.034). This increase in dietary indigestible protein contents resulted in a decrease (P = 0.001) in total cecal volatile fatty acid concentration from 209.1 to 125.9 mmol/kg of DM digesta in broilers with increasing RSM in diets. Increase in the indigestible protein level, from RSM-0% to RSM-100%, resulted in a decrease (P = 0.042) in villus heights (1,782 vs. 1,574 µm), whereas crypt depths increased (P = 0.021; 237 vs. 274 µm). A coarse diet improved feed intake (P = 0.006), BW gain (P = 0.014), and feed conversion ratio (P = 0.009). Broilers fed coarse diets had approximately 11, 24, and 10% lower relative empty weights of the crop, proventriculus, and jejunum, respectively, whereas a 15% heavier gizzard was found compared with those fed the fine diets. Dietary coarseness resulted in approximately 16% lower gizzard pH, 21% greater villus heights, 27% lower crypt depths, 24% reduced branched-chain fatty acids, and 12% lower biogenic amines in the cecal digesta compared with broilers fed fine diets. In conclusion, feeding coarse particles improved broiler performance irrespective of digestibility of the diet. Hindgut protein fermentation can be reduced by coarse grinding of the diet.

The objective of this study was to determine the effects of different growth patterns and dietary crude protein levels during rearing in broiler breeder females on fertility, hatchability, embryonic mortality, and offspring performance. A 2×3 factorial arrangement of treatments was used, with 2 growth patterns to reach a target body weight at 20 wk of age of 2,200 g (standard=standard growth pattern) or 2,400 g (high=high growth pattern), and 3 dietary protein levels (high=crude protein, high), (medium=crude protein, medium), and low=crude protein, low). Fresh egg composition and organ development in hatchlings were determined. Offspring of the different groups were reared until an age of 34 d and feed intake, body weight gain, mortality, and carcass composition were determined. In 29-wk-old high growth pattern breeders compared to standard growth pattern breeders, fertility and hatchability of set eggs were increased; embryonic mortality between d 1 and 9 was decreased whereas hatchability of fertile eggs was not affected. Breeders fed the medium crude protein diet showed a decreased hatchability of fertile eggs caused by an increased embryonic mortality between d 18 and 21 compared to breeders fed the high crude protein and low crude protein diets. Offspring of 29-wk-old high growth pattern breeders tended (P=0.059) to have a higher body weight at d 34 than offspring of standard growth pattern breeders, which was achieved by a tendency to a higher body weight gain (P=0.057). Offspring of breeders fed the medium and low crude protein diet showed a higher feed intake between d 18 and 27 and during the total growth period, as compared to offspring of high crude protein breeders. Male broilers of low crude protein breeders had higher breast meat yield than male broilers of high crude protein breeders, while breast meat yield of female broilers was not affected by dietary protein levels. This experiment showed that a higher growth pattern during the rearing period increased fertility, decreased embryonic mortality, and improved offspring performance in young breeders, whereas decreased dietary protein level had no or less pronounced effects on these traits.