An experiment was conducted to determine the effect of the form of dietary fat (extracted or intact fat) and of dietary NDF on ileal and total tract endogenous losses of fat (ELF), on apparent ileal (AID) and apparent total tract digestibility (ATTD) of fat, and on true ileal (TID) and true total tract digestibility (TTTD) of fat in growing pigs. A cornstarch-based basal diet that contained 1.27% fat was prepared and 3 diets were formulated by adding 2.0, 4.0, or 6.0% extracted fat (corn oil) to the basal diet at the expense of cornstarch. Three additional diets were formulated by adding 3.1, 6.2, or 9.3% Solka-Floc (International Fiber Corp., North Tonawanda, NY) to the diet containing 4.0% corn oil at the expense of cornstarch. The remaining 4 diets were prepared by adding whole corn germ meal to the diet at the expense of defatted corn germ meal to contain 3.0, 6.0, or 9.0% intact fat. Solka-Floc was also included in this diet at the expense of cornstarch in an attempt to keep NDF constant. Eleven barrows (initial average BW of 38.1 +/- 1.3 kg) were fitted with a T-cannula in the distal ileum, allotted to the 11 diets in an 11 x 11 Latin square design, and fed the diets at 3 times the energy requirement for maintenance. Increasing dietary extracted fat increased (linear and quadratic, P < 0.001) the AID and ATTD of fat. Increasing dietary intact fat also increased (linear and quadratic, P < 0.05) the AID and ATTD of fat. The average apparent digestibility of extracted fat (81.9%) was greater (P < 0.001) than that of intact fat (63.2%). Estimates of ELF were smaller (P < 0.05) for extracted fat than for intact fat at the end of the ileum and over the entire intestinal tract, but the TID (93.8%) and TTTD (94.2%) of extracted fat were greater (P < 0.05) than the TID (78.6%) and TTTD (84.1%) of intact fat. Increasing dietary extracted fat had no effects on the TID and TTTD of fat, but increasing dietary intact fat resulted in a quadratic reduction (P < 0.05) in the TTTD of fat. Increasing dietary NDF had a quadratic effect (P < 0.05) on the ATTD of fat but did not influence the AID, TID, and TTTD of fat. In conclusion, extracted fat induces a smaller amount of ELF and has a greater apparent and true digestibility than intact fat at the end of the ileum and over the entire intestinal tract. Purified NDF has little influence on apparent and true digestibility of fat.

The present experiment was conducted to investigate the effect of heat stress (HS) andstocking density (SD) on growth performance, breast meat quality, and intestinal barrier functionin broiler chickens. Experimental treatments included two different ambient temperatures (20 °C:thermoneutral conditions, or 27.8 °C: HS conditions) and two different SD (low: 9 birds/m2 andhigh: 18 birds/m2) in a 2 × 2 factorial arrangement. A total of 1140 21-day-old broiler chickens wereallotted 1 of 4 treatments with five replicates. At the end of the experiment (35 days of age), twobirds per replicate were euthanized for sample collections. The results indicated no interactionsbetween HS and SD for all measurements. For main effects, HS decreased (p < 0.05) the growthperformance of broiler chickens. Similarly, high SD also decreased (p < 0.05) body weight gain andfeed intake. HS decreased (p < 0.01) jejunal trans-epithelial electric resistance (TER), whereas highSD did not affect TER. Neither HS nor high SD affected jejunal tight junction-related geneexpressions; however, high SD reduced (p < 0.05) occludin expression. In conclusion, HS and highSD are key environmental factors decreasing broiler performance; however, the interactive effectsof HS and high SD are not significant under the current conditions.

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Dietary acidifiers appear to be a possible alternative to feed antibiotics in order to improve performance of weaning pigs. It is generally known that dietary acidifiers lower gastric pH, resulting in increased activity of proteolytic enzymes, improved protein digestibility and inhibiting the proliferation of pathogenic bacteria in GI tract. It is also hypothesized that acidifiers could be related to reduction of gastric emptying rate, energy source in intestine, chelation of minerals, stimulation of digestive enzymes and intermediate metabolism. However, the exact mode of action still remains questionable. Organic acidifiers have been widely used for weaning pigs' diets for decades and most common organic acidifiers contain fumaric, citric, formic and/or lactic acid. Many researchers have observed that dietary acidifier supplementation improved growth performance and health status in weaning pigs. Recently inorganic acidifiers as well as organic acidifiers have drawn much attention due to improving performance of weaning pigs with a low cost. Several researchers introduced the use of salt form of acidifiers because of convenient application and better effects than pure state acids. However, considerable variations in results of acidifier supplementation have been reported in response of weaning pigs. The inconsistent responses to dietary acidifiers could be explained by feed palatability, sources and composition of diet, supplementation level of acidifier and age of animals.

In the poultry industry, many efforts have been undertaken to further improve the growth performance of broilers and identification and modulation of body weight (BW)-related bacteria could be one of the strategies to improve productivity. However, studies regarding the relationship between microbiota and BW are scarce. The objective of the present study was to investigate the relationship between microbiota and BW in different sections of the gastrointestinal tract (GIT). A total of twenty 18-day-old birds were selected based on the BW, and samples were collected from the three different sections of the GIT, which included the crop, ileum and cecum. Bacterial genomic DNA was extracted from the samples, and the V4 region of 16S rRNA gene were amplified. Amplicons were sequenced on Illumina MiSeq, and microbial communities were analyzed by using QIIME. In principal coordinate analysis, bacterial communities were clustered into three groups, based on the sections of GIT. Several BW-related bacterial groups were identified from linear regression analysis. At the genus level, Streptococcus from the ileum as well as Akkermansia in both ileum and cecum, were negatively related to BW, whereas Bifidobacterium in the ileum and Lactococcus in the cecum showed a positive correlation. The results from the present study showed that particular bacterial communities in the GIT were related to BW, and the study has broadened the understanding of the intestinal microbial ecosystem in broiler chickens.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-2604-8) contains supplementary material, which is available to authorized users.