Sex differences in intestinal morphology and increase in diencephalic neuropeptide Y gene expression in female but not male Pekin ducks exposed to chronic heat stress.

The impact of heat stress (HS) on production is intricately linked with feed intake. We investigated the effects of HS on intestines and diencephalic genes in Pekin ducks. One hundred and sixty adult ducks were allocated to two treatment rooms. The control room was maintained at 22°C and the HS room at 35°C for the first 10 h of the day then reduced to 29.5°C. After 3 weeks, 10 hens and 5 drakes were euthanized from each room and jejunum and ileum collected for histology. Brains were collected for gene expression analysis using qRT-PCR. Intestinal morphology data were analyzed with two-way ANOVA and diencephalic gene data were analyzed with Kruskal-Wallis test. There was an increase in villi width in the ileum (p = .0136) and jejunum (p = .0019) of HS hens compared to controls. HS drakes showed a higher crypt depth (CD) in the jejunum (p = .0198) compared to controls. There was an increase in crypt goblet cells (GC) count in the ileum (p = .0169) of HS drakes compared to HS hens. There was higher villi GC count (p = .07) in the jejunum of HS drakes compared to controls. There was an increase in the crypt GC density (p = .0054) in the ileum, not jejunum, of HS drakes compared to HS hens. Further, there were no differences in the proopiomelanocortin gene expression in either sex but there was an increase in the expression of neuropeptide Y (NPY) gene in HS hens (p = .031) only and a decrease in the corticotropin releasing hormone gene in the HS drakes (p = .037) compared to controls. These data show that there are sex differences in the effect of HS on gut morphology while the upregulation in NPY gene may suggest a role in mediating response to chronic HS.

Dietary phosphorus level regulates appetite through modulation of gut and hypothalamic expression of anorexigenic genes in broiler chickens.

Two experiments were designed to elucidate gut and hypothalamic molecular regulation of appetite by dietary phosphorus (P) concentration in broiler chickens. Birds (192 Cobb-500 broiler chickens) were randomly assigned to 3 experimental diets in experiment 1 (Exp. 1) and 24 broiler chickens were randomly assigned to 3 treatment groups in Exp. 2. Each diet comprised 8 replicate cages, with either 8 birds (Exp. 1) or 1 bird (Exp. 2) per replicate cage. In Exp. 1, diets contained 1.2 (P-deficient), 2.8 (P-marginal) or 4.4 (P-adequate) g/kg non-phytate P (nPP). In Exp. 2, birds fed the P-adequate diet were pair-fed (PF) to the feed consumption levels of birds fed the P-deficient diet. Feed intake and BW gain (P < 0.001) decreased in birds fed the P-deficient diet in Exp. 1. Birds fed the P-deficient diet had similar feed intake and BW gain with PF group fed the P-adequate diet (Exp. 2) but was significantly lower (P < 0.001) than birds fed the P-adequate diets. Sodium-phosphate cotransporter (NaPi-IIb) mRNA was upregulated (P < 0.05) in both experiments. Conversely, cholecystokinin (CCK) mRNA was downregulated (P < 0.01) in birds fed P-deficient diets. Anorexia-related hypothalamic cholecystokinin receptor (CCKAR) and melanocortin receptors (MC3R and MC4R) were upregulated (P < 0.05) in birds fed P-deficient diets, in both experiments. The current data show that dietary P deficiency decreases feed intake in broiler chickens by altering the expression of anorexigenic genes in the gut and hypothalamus of broiler chickens.

Contribution of purified soybean trypsin inhibitor and exogenous protease to endogenous amino acid losses and mineral digestibility.

The primary objective of the current study was to evaluate the impact of trypsin inhibitor (TI) and exogenous protease supplementation on endogenous loss of amino acids (AA) in broiler chickens. A total of 384 Cobb-500 broiler chicks were allocated to 4 nitrogen-free diets, each with 8 replicate cages and 12 birds per replicate. The diets were arranged as a 2 × 2 factorial with factors being dietary TI (0 or 8,000 TIU/g) and exogenous protease (0 or 15,000 PROT/kg). Desired dietary TI concentration was achieved by addition of commercially available, purified soybean TI. There was no effect of TI or exogenous protease or their interaction on growth performance of birds. However, the endogenous loss of nitrogen (N) and all AA increased (P < 0.05) due to dietary TI concentration except for Cys. The increase in endogenous AA due to TI ranged from 17% for Thr to 52.2% for Trp. Exogenous protease had no effect on endogenous loss of N and all AA. There was no effect of TI or exogenous protease or their interaction on the AID of P, however AID of Ca, Fe, Mg, Mn, and Cu was reduced (P < 0.05) due to dietary TI. The AID of Cu (P < 0.01) and K (P < 0.05) improved with exogenous protease supplementation. Significant interactions (P < 0.05) between exogenous protease and TI existed for Zn, Mg, Cu, and Na. The concentration (g/kg DM intake) of crude mucin and sialic acid increased (P < 0.05) with increased dietary TI. Decreased trypsin (P < 0.001) and increased chymotrypsin (P < 0.001) activity in the pancreas were observed as a result of exogenous protease supplementation. In conclusion, the current study showed that TI increases the endogenous loss of AA and reduced the digestibility of minerals in broiler chickens. Furthermore, exogenous protease did not affect endogenous AA flow, irrespective of added purified dietary TI.

Adipose tissue-specific responses reveal an important role of lipogenesis during heat stress adaptation in pigs.

Elevated ambient temperature causes heat stress in pigs, resulting in reduced animal performance. To better understand tissue responses to heat stress in pigs, we conducted a study in which pigs were subjected to four treatments: acute (24 h) heat stress (AHS) at 35 °C ± 1 ambient temperature, chronic (7 d) heat stress at 35 °C ± 1 (HS) or normal ambient temperature (20 °C± 1) for 7 d with ad-libitum feeding (Con) or with pair-feeding to the feed intake (FI) of the HS pigs (PF). Heat stress decreased FI by approximately 36% and 64% in HS and AHS treatments respectively, compared with Con (P < 0.01). Concentration of free fatty acids (FFA) was elevated in AHS compared to HS (P = 0.031). Serum insulin concentration was lower in PF than Con (P = 0.045). Blood urea nitrogen (BUN) concentration was elevated in HS compared with Con and PF (P = 0.008), but lower (P < 0.021) in AHS compared to HS. In the subcutaneous adipose tissue, the mRNA and protein abundance of PCK1 were higher (P < 0.05) in the HS treatment than Con and PF, and also higher (P < 0.05) in HS than AHS. However, there was no difference in GK mRNA between Con, PF, and HS, although its expression was lower (P = 0.003) in AHS vs. HS. Protein abundance of the ER stress marker, CCAT/enhancer-binding homologous protein (CHOP), was higher in PF than Con (P < 0.05), and higher (P = 0.033) in HS than AHS in subcutaneous fat. In mesenteric fat, PCK1 mRNA was higher (P < 0.001) in the HS than Con and PF treatments. Additionally, expression of PCK1 was lower (P = 0.039) in AHS vs. HS. Expression of PCK1 was downregulated (P < 0.05) in the liver of PF pigs compared to other treatments, but most other genes measured were not affected by treatment in the liver and muscle tissues. These results confirm that heat stress induces a robust adipose tissue response in favor of increased lipid storage. This indicates that adipose tissue might play an important role in heat stress adaptation.

Investigation of carryover effect of prior fibre consumption on growth, serum and tissue metabolic markers in Ossabaw pigs fed a high-fat diet.

Carryover effect of prior fibre consumption on metabolic markers was investigated. Treatments were arranged in 2 × 2 factorial with 2 fibre sources, 4% inulin or cellulose (Solka-Floc®) and fat levels (5 or 15%) for the low-fat diet (LFD) and high-fat diet (HFD) respectively. Pigs were fed the two fibre diets for the first 56d (nursery phase), and thereafter fed either the LFD or HFD containing no added fibre source from d56 to 140 (growing phase). Pigs on the HFD were heavier (p = .05) than those on LF (64.61 vs. 68.38 kg), regardless of prior fibre type consumed. Pigs that were fed cellulose during the nursery and later fed the HFD had the highest ADG (p < .05). Feeding the HFD resulted in higher back fat (BF) (13.41 and 18.18 ± 0.12 mm for LFD and HFD, respectively; p < .01). The HFD resulted in higher (p < .01) insulin (0.014 and 0.016 ± 0.001 mg/L for LF and HF respectively) and glucose (100.89 and 125.03 ± 4.39 mg/dl for LF and HF respectively) concentrations in the serum. Inulin increased (p ≤ .02) jejunal expression of SREBP-1c and CL-4, but reduced (p < .05) TNFɑ and IL-6 expression in the ileum. Alpha-diversity was significantly different (p < .05) between the inulin and cellulose fed pigs at the end of the nursery and finishing phases. Therefore, inulin feeding before a HFD may lead to reduction in ADG and inflammatory markers in the small intestine of pigs, and thus prevent future metabolic disorders.

Effect on Rendement Napole genotype on metabolic markers in Ossabaw pigs fed different levels of fat.

We investigated effects of Rendement Napole (RN) genotype on metabolic markers in Ossabaw pigs fed diets with different levels of dietary fat. Thirty-two pigs, belonging to either the wild-type (WT, rn+ /rn+ ) or carrier (CAR, RN- /rn+ ) genotypes (n = 16/genotype), were divided into two dietary groups, (high fat [HF] or low fat [LF]) diets, for 12 weeks (n = 8 pigs/genotype/diet) after which pigs were killed for gene expression analysis by RT-PCR. Feeding HF diet caused increased daily gain (ADG, p < .05) and final body weight (BW) (p < .05) in comparison with the LF diet (p < .05). Feed efficiency (gain:feed) was higher (p < .05) in pigs on the HF and was higher (p < .05) in CAR pigs compared to WT. There was genotype × diet interaction (p = .05) on final BW such that CAR animals on LF diet had the same final BW as animals of both genotypes on HF diet. Carrier pigs on LF diet had higher (p < .05) average daily gain and gain:feed than WT pigs. There was a trend (p < .08) for a higher feed consumption in pigs on the LF diet. Backfat thickness was higher (p < .01) in pigs on the HF diet. Serum triglyceride was higher (0.62 vs. 0.33 mg/dl, p < .01) in pigs on HF diet. Serum insulin was higher (p < .05) in CAR versus WT pigs (0.40 vs. 0.015 µg/ml). Pigs on the HF diet had a higher (p < .05) serum insulin compared to those on the LF diet (0.032 vs. 0.023 µg/ml). Carnitine palmitoyl transferase 1-alpha was higher (p < .05) in the longissimus dorsi and semitendinosus muscles of pigs on HF diet. Acyl-CoA oxidase I was elevated (p < .05) in the liver of pigs on HF diet. Fatty acid synthase was lower in the longissimus dorsi muscle, liver and mesenteric fat (p < .05) of carrier pigs. The RN gene regulates specific metabolic markers in the Ossabaw pigs.

Garlic diallyl disulfide and diallyl trisulfide mitigates effects of pro-oxidant induced cellular stress and has immune modulatory function in LPS-stimulated porcine epithelial cells.

The objective of the current study was to determine if garlic-derived diallyl disulfide (DADS) and diallyl trisulfide (DATS) could mitigate oxidative and endotoxin stress, using an intestinal porcine epithelial cell (IPEC-J2) model. The experiment was arranged as a 2 × 2 × 2 factorial of DADS + DATS (0 or 18 µM), pro-oxidant stressor (hydrogen peroxide at 0 or 100 µM), and endotoxin stressor (lipopolysaccharide [LPS] at 0 or 10 µg/mL) with 8 replicates per treatment. Cells were incubated with DADS + DATS for 18 h, LPS for 6 h, then with hydrogen peroxide for 3 h. Gene expression was measured by RT-PCR for cytokines, interleukin 8 (IL-8) and tumor necrosis factor α (TNF-α), and tight junction proteins, claudin 1 (CL-1), occludin (OC), and zonula occludens 1 (ZO-1). Trans-epithelial electrical resistance (TEER), the antioxidant enzyme catalase, and apical secretion of IL-8 protein into the incubation medium was also measured. There was an increase ( < 0.01) in TNF-α and IL-8 gene expression due to LPS, although there was no effect of hydrogen peroxide or DADS + DATS. Furthermore, there was a tendency for an increase ( = 0.08) in ZO-1 gene expression due to DADS + DATS. Treatment with DADS + DATS and hydrogen peroxide did not affect TEER, although there was a decrease ( = 0.02) in TEER with LPS incubation. Treatment of cells with hydrogen peroxide reduced catalase activity ( < 0.01), which was restored with pre-incubation of DADS + DATS ( < 0.10). There was an increase ( < 0.01) in IL-8 secretion due to LPS, which was further augmented ( < 0.01) by pre-incubation with DADS + DATS. Based on the results from the current study, DADS + DATS can ameliorate oxidative effects of hydrogen peroxide, as well as alter IL-8 secretion in LPS-treated IPEC-J2 cells.

Ability of garlic-derived diallyl disulfide and diallyl trisulfide supplemented by oral gavage to mitigate effects of an acute postweaning feed and water deprivation event in nursery pigs.

Compounds in garlic have been shown to contain anti-inflammatory, antioxidant, and immune modulatory properties that may be able to mitigate the effects of nursery pig stressors. The objective of the current experiment was to determine if oral gavage of garlic-derived diallyl disulfide (DADS) and diallyl trisulfide (DATS) could mitigate the effects of a 24-h postweaning feed + water deprivation event in nursery pigs. Pigs (6.0 ± 0.05 kg and 21 d old) were allotted to 4 treatments in a randomized complete block design at weaning with 8 replicate pens per treatment that consisted of with or without a 24-h postweaning feed + water deprivation event and with or without an oral gavage containing 3.6 mg DADS + DATS/kg BW. Growth performance and morbidity were recorded throughout the experiment, and on 1, 6, and 21 d after weaning, 1 pig per pen was selected, blood was collected, the pig was euthanized, and a segment of the distal ileum was subsequently excised for morphological and gene and protein expression measurements. Mucosal gene expression was conducted by reverse transcription PCR for immune, antioxidant, and cellular integrity markers. Furthermore, activity of mucosal superoxide dismutase was measured by colorimetric assay. Immediately following the feed + water deprivation event, there was a decrease ( < 0.01) in growth performance and an increase ( = 0.01) in serum cortisol. The feed + water deprivation event tended ( = 0.10) to decrease ileal villus height and supplementation of DADS + DATS by oral gavage increased ( = 0.03) villus height 1 d after weaning. Supplementation of DADS + DATS by oral gavage decreased ( = 0.03) and tended to decrease ( = 0.08) gene expression of on 6 and 21 d after weaning, respectively. Furthermore, at 1 d after weaning, ileal mucosa SOD activity was decreased ( = 0.01) by the feed + water deprivation and increased ( = 0.04) by oral supplementation of DADS + DATS. Expression of the tight junction genes and were reduced ( ≤ 0.05) due to the feed + water deprivation event 1 d after weaning. Results from the current study show that an acute feed + water deprivation event can impact growth performance, intestinal characteristics, and antioxidant status in nursery pigs, which can be partially mitigated by oral supplementation of garlic compounds DADS + DATS.

Effect of threonine on secretory immune system using a chicken intestinal ex vivo model with lipopolysaccharide challenge.

Secretory IgA (sIgA) and its transcytosis receptor, polymeric immunoglobulin receptor (pIgR), along with mucus, form the first lines of intestinal defense. Threonine (Thr) is a major component of intestinal mucins and IgA, which are highly secreted under lipopolysaccharide (LPS) induced inflammation. In the current study, the effect of Thr on the secretory immune system was determined in an ex vivo chicken ileal explant model. Results showed that a 2-hour Thr-deprivation of culture medium induced a compensatory increase in the mRNA expression of interleukin-8 (IL-8), mucin 2 (MUC2), and IgA during LPS challenge, and this increase was suppressed with Thr addition to the media (P ≤ 0.05), suggesting that Thr was required for mucin and IgA production after exposure to LPS. Similarly, a 2-hour culture of explants from birds fed a Thr adequate diet showed an increase in the mRNA abundance of IL-8, MUC2, and IgA with LPS treatment (P ≤ 0.003), which had a trend to be attenuated with Thr supplementation in the media (P ≤ 0.10). In contrast, explants from birds fed a Thr deficient diet had no response to LPS treatment. These results indicated that in vivo Thr deficiency induced impaired inflammatory and secretory immune responses in broiler chicks. Furthermore, our results revealed that induction of MUC2 and pIgR gene expression required nuclear factor-κB (NF-κB) activation. Additionally, IgA transcytosis may be dependent on extracellular-regulated protein kinase (ERK) activation, which may indirectly impact pIgR gene expression.

Effects of dietary resistant starch content on metabolic status, milk composition, and microbial profiling in lactating sows and on offspring performance.

In the present study, the effects of dietary resistant starch (RS) content on serum metabolite and hormone concentrations, milk composition, and faecal microbial profiling in lactating sows, as well as on offspring performance was investigated. Sixteen sows were randomly allotted at breeding to two treatments containing low- and high-RS contents from normal and high-amylose corn varieties, respectively, and each treatment had eight replicates (sows). Individual piglet body weight (BW) and litter size were recorded at birth and weaning. Milk samples were obtained on day 10 after farrowing for composition analysis. On day 2 before weaning, blood and faecal samples were collected to determine serum metabolite and hormone concentrations and faecal microbial populations, respectively. Litter size at birth and weaning were not influenced (p > 0.05) by the sow dietary treatments. Although feeding the RS-rich diet to sows reduced (p = 0.004) offspring birth BW, there was no difference in piglet BW at weaning (p > 0.05). High-RS diet increased (p < 0.05) serum triacylglycerol and nonesterified fatty acid concentrations and milk total solid content, and tended (p = 0.09) to increase milk fat content in lactating sows. Feeding the RS-rich diet to sows increased (p < 0.01) faecal bacterial population diversity. These results indicate that high-RS diets induce fatty acid mobilization and a greater intestinal bacterial richness in lactating sows, as well as a greater nutrient density in maternal milk, without affecting offspring performance at weaning.

Heat stress in pigs is accompanied by adipose tissue-specific responses that favor increased triglyceride storage.

Heat stress (HS) negatively affects all aspects of performance in pigs. Although certain tissue-specific responses in the liver, skeletal muscle, and intestine are known, there is paucity of information on responses within the adipose tissue. Therefore, the objective of this study was to delineate adipose tissue responses during HS in pigs. Thirty crossbred (Ossabaw × Duroc × Landrace) pigs were assigned to 3 treatments for 7 d. Treatments were 1) control and libitum fed (CON) with room temperature set at 20°C ± 1°C, 2) pair fed (PF) with room temperature as the CON treatment but pair fed to HS pigs, and 3) HS with room temperature 35°C ± 1°C and ad libitum access to feed. Compared with CON pigs, HS pigs had decreased feed intake and elevated skin temperature and respiration rate ( < 0.01). Blood urea nitrogen was higher ( = 0.01) in HS pigs compared with CON pigs only in males. In both subcutaneous and mesenteric adipose tissue, mRNA abundance of phosphoenolpyruvate carboxykinase (PCK1) was more elevated ( < 0.01) in HS groups compared with the CON and PF groups. Heat stress also caused increased heat shock protein 70 (HSP70; = 0.067) and CCAT/enhancer-binding homologous protein (CHOP) content ( < 0.05) in the mesenteric fat compared with the CON treatment. In conclusion, induction of PCK1 expression in adipose tissue by HS suggests elevated glyceroneogenesis might be involved in the increased fat storage in pigs under HS.

Phosphorus and nitrogen utilization responses of broiler chickens to dietary crude protein and phosphorus levels.

A study was conducted to investigate the effect of dietary CP levels on pre-cecal digestibility and total tract retention of phosphorus (P) in broiler chickens. A total of 384 14-day-old male broiler chickens were used in a randomized complete block design with 8 treatments and 6 replicates per treatment in a 7-d experimental period. There were 8 corn-soybean meal-based diets in a 2 × 4 factorial arrangement, which included 2 CP levels (10.7 or 21.5%) and 4 apparent total tract digestible P (ATTDP) levels (0.18, 0.32, 0.45, or 0.59%). Soybean meal and mono-calcium phosphate were used to adjust the CP and ATTDP levels, respectively. At the end of the experiment, BW was recorded and digesta samples from the distal two-thirds of ileum and mucosa samples from the middle of the jejunum were collected. Total RNA also was isolated from mucosa samples and used for real-time PCR to determine the gene expression of sodium-phosphate co-transporter IIb (NaPi-IIb). Results showed that low dietary CP level limited the growth performance (P < 0.01), pre-cecal digestion, and total tract retention of P (P < 0.01), and NaPi-IIb gene expression (P < 0.05), compared with high dietary CP. Pre-cecal digestion and total tract retention of P (g/kg DM intake) linearly increased (P < 0.01) with increasing ATTDP levels in both low and high CP groups. In conclusion, this study suggests an interrelationship between N and P digestion such that CP deficiency decreased the growth performance of birds consequently reducing pre-cecal P digestion in broiler chickens. Total tract retention of CP and P are linked with each other and body tissue growth may be a driver of the deposition of these 2 nutrients. Supplementation of protein may be necessary in diets during P digestibility studies to ameliorate an effect of protein deficiency on P digestion and retention.

Age-related energy values of bakery meal for broiler chickens determined using the regression method.

A study was conducted to determine the ileal digestible energy (IDE), ME, and MEn contents of bakery meal using the regression method and to evaluate whether the energy values are age-dependent in broiler chickens from zero to 21 d post hatching. Seven hundred and eighty male Ross 708 chicks were fed 3 experimental diets in which bakery meal was incorporated into a corn-soybean meal-based reference diet at zero, 100, or 200 g/kg by replacing the energy-yielding ingredients. A 3 × 3 factorial arrangement of 3 ages (1, 2, or 3 wk) and 3 dietary bakery meal levels were used. Birds were fed the same experimental diets in these 3 evaluated ages. Birds were grouped by weight into 10 replicates per treatment in a randomized complete block design. Apparent ileal digestibility and total tract retention of DM, N, and energy were calculated. Expression of mucin (MUC2), sodium-dependent phosphate transporter (NaPi-IIb), solute carrier family 7 (cationic amino acid transporter, Y(+) system, SLC7A2), glucose (GLUT2), and sodium-glucose linked transporter (SGLT1) genes were measured at each age in the jejunum by real-time PCR. Addition of bakery meal to the reference diet resulted in a linear decrease in retention of DM, N, and energy, and a quadratic reduction (P < 0.05) in N retention and ME. There was a linear increase in DM, N, and energy as birds' ages increased from 1 to 3 wk. Dietary bakery meal did not affect jejunal gene expression. Expression of genes encoding MUC2, NaPi-IIb, and SLC7A2 linearly increased (P < 0.05) with age. Regression-derived MEn of bakery meal linearly increased (P < 0.05) as the age of birds increased, with values of 2,710, 2,820, and 2,923 kcal/kg DM for 1, 2, and 3 wk, respectively. Based on these results, utilization of energy and nitrogen in the basal diet decreased when bakery meal was included and increased with age of broiler chickens.

Heat stress enhances adipogenic differentiation of subcutaneous fat depot-derived porcine stromovascular cells.

Heat stress (HS) results from excessive heat load on animals such that all adaptive mechanisms used to dissipate the heat do not return the body to normal body temperature. In pigs, HS results in increased fat deposition compared with pair-fed animals in a thermoneutral environment. Although there is evidence that HS increases activity of lipoprotein lipase (LPL) in adipose tissue of heat stressed pigs, the fundamental causes of the increased adiposity are still unknown. It remains unclear whether HS directly alters metabolism in adipocytes. Therefore, to understand the mechanism of HS effects on porcine adipocytes, we used an in vitro adipocyte differentiation model to characterize cellular responses that occur during differentiation of pig adipocytes. Preadipocytes (stromovascular cells) were differentiated for 9 d at a normal (37°C) or HS (41.5°C) temperature under 5% CO. Expressions of HS genes such as heat shock proteins (HSP; HSP27, HSP60, HSP70, and HSP90), adipogenic markers peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding proteins α (C/EBPα), fatty acid synthase (FAS), adipocyte protein 2 (aP2), fatty acid translocase 36 (CD36), fatty acid transport protein 4 (FATP4), fatty acid transport protein 6 (FATP6), LPL, glucose transporter protein type 4 (GLUT4), phosphoenolpyruvate carboxykinase 1 (PCK1 or PEPCK-C), and glycerol kinase (GK) and adipokines (adiponectin and leptin) were determined by real-time-PCR and immunoblotting or ELISA. Cellular triglyceride (TAG) and ATP concentrations were also determined. As expected, HS increased ( < 0.05) the expressions of HSP genes. There was no HS treatment effect on the level of PPARγ, although C/EBPα was induced ( < 0.05) in HS. So it remains unclear whether HS affects adipocyte differentiation. However, HS leads to increased expressions of genes involved in fatty acid uptake and TAG synthesis (FAS, aP2, CD36, FATP4, FATP6, LPL, GLUT4, PCK1, and GK). This is supported by increased cellular TAG under HS. Therefore, HS promotes increased adipocyte TAG storage, perhaps through upregulation of genes involved in fatty acid uptake and TAG synthesis.

Impact of acute water and feed deprivation events on growth performance, intestinal characteristics, and serum stress markers in weaned pigs.

The impact of acute stressors (24-h feed or water deprivation) on growth performance, intestinal characteristics, and serum stress markers in weaned pigs was evaluated. Pigs (6.21 ± 0.29 kg) were allotted in a randomized complete block design to 4 treatments on the basis of BW at the time of weaning. There were 8 mixed-sex pigs in each of 12 pens per treatment. Treatments were arranged as a 2 × 2 factorial and consisted of a feed or water stressor that included a 0- or 24-h deprivation period postweaning, and pigs were subsequently allowed access to feed and water. Growth performance was measured 1, 7, 14, and 28 d postweaning. Serum and intestinal samples were taken 1 and 7 d postweaning. Serum was analyzed for cortisol and corticotrophin-releasing factor, and villus height, crypt depth, and mast cell density were measured in the jejunum and the ileum. Expression of mucin (MUC2), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), claudin 1 (CL-1), occludin (OC), and zonula occludens 1 (ZO-1) genes were measured on d 1 and 7 postweaning in the jejunum and ileum by real-time PCR. There was a decrease (P < 0.05) in ADG with the water stressor 1 d postweaning, although subsequently, there were improvements (P < 0.05) in ADG and feed efficiency. Furthermore, the water stressor reduced ADFI during the last 14 d of the trial and cumulatively (P < 0.05). Seven days postweaning there was an increase (P < 0.05) in jejunal villous height to depth ratio due to the feed stressor and a decrease (P < 0.05) in the ileal villous height to depth ratio due to the water stressor. There was an increase (P < 0.05) in serum cortisol levels due to the water stressor both 1 and 7 d postweaning. Furthermore, there was an increase in serum corticotrophin-releasing factor 1 d but not 7 d postweaning due to the water stressor (P < 0.05). The feed stressor reduced (P < 0.05) TNF-α gene expression, and the water stressor reduced (P < 0.05) OC gene expression in the jejunum 1 d postweaning. In the ileum, there was a reduction in CL-1 and ZO-1 gene expression (P < 0.05) due to the water stressor 7 d postweaning. The results from the current investigation showed that a 24-h feed or water deprivation at the time of weaning has negative impacts on growth performance, intestinal characteristics, and serum stress responses immediately following the stress event and throughout the nursery period.

Assessment of a bacterial 6-phytase in the diets of broiler chickens.

Two 21-d broiler experiments were conducted to assess the efficacy of a bacterial 6-phytase expressed in Aspergillus oryzae on growth performance, nutrient utilization, and intestinal molecular markers. Two hundred forty birds in 5 treatments (experiment 1) or 256 birds in 4 treatments (experiment 2) were used. The treatments included a negative control diet that was marginally deficient in P (NC) or NC plus tricalcium phosphate, 500, 1,000, or 2,000 phytase units/kg (experiment 1), and NC or NC plus monocalcium phosphate, 500 or 1,000 phytase units/kg (experiment 2). In both experiments, excreta were collected on d 19 to 21, whereas birds and feed were weighed and ileal digesta collected on d 21. For experiment 1, mucosa scraping was collected from the duodenum, jejunum, and ileum from all birds for quantification of expression level of gut level inflammatory cytokines, Toll-like receptors, and phosphate transporter (NaPi-IIb). In both experiments, tricalcium phosphate, monocalcium phosphate, and phytase supplementation improved (P < 0.05) weight gain and percentage tibia ash. Phosphorus and Ca retention and phytic acid disappearance improved (P < 0.05) with phytase supplementation (experiment 1) and there was an increase (P < 0.01) in Ca and P retention in response to phytase supplementation (experiment 2). Diets did not affect the expression of gut level cytokines, Toll-like receptors, or the mucin gene. Phytase supplementation tended to decrease (P < 0.10) the expression of NaPi-IIb. It was concluded from these studies that the bacterial 6-phytase was effective in enhancing growth of broilers receiving low-P diets as well as in increasing efficiency of P utilization and phytic acid degradation.

Ileal endogenous amino acid losses: response of broiler chickens to fiber and mild coccidial vaccine challenge.

The effects of mild coccidial vaccine (5× dose) challenge and fiber levels on ileal endogenous amino acid (EAA) losses was determined in 26-d-old broiler chickens using the regression method. Birds were fed semipurified diets containing 3 levels of casein (40, 80, or 120 g/kg of diet) as the only source of dietary protein at 2 levels of fiber (purified cellulose at 25 or 75 g/kg of diet). One half of the experimental birds were gavaged with coccidial vaccine on d 20. The 3 levels of casein were used to determine EAA losses for each replicate cage of birds. The design of the study was a randomized complete block employing a factorial arrangement of treatments with 2 levels of coccidial challenge (control or unchallenged, and challenged) and 2 levels of fiber, with 6 replicate cages per treatment and 8 birds per cage. Birds were killed on d 26 and contents from the entire ileum were flushed with distilled water and stored at -20°C until processed. Ileal EAA losses were determined from the ordinate intercept, at zero amino acid (AA) intake, of the regression of ileal digesta AA concentration in milligrams per kilogram of DM intake against dietary AA intake in milligrams per kilogram of DM. The effect of fiber level on EAA losses, expressed in milligrams per kilogram of DM intake, were higher (P < 0.05) for most of the AA in birds fed 25 g of fiber/kg of diet. Coccidial vaccine challenge decreased (P < 0.05) EAA losses for 8 of the 18 AA. A significant interaction between fiber level and coccidial vaccine challenge was obtained for all AA except His and Lys. Coccidial vaccine challenge resulted in increased (P < 0.05) NaPi-IIb expression. The results suggest that ileal EAA loss is higher in challenged birds fed the diet containing 25 g of fiber/kg of diet. Changes in EAA losses as a result of dietary fiber level and coccidial infection are important in amino acid nutrition of the broiler chicken.

Butyrate supplementation to gestating sows and piglets induces muscle and adipose tissue oxidative genes and improves growth performance.

Weaned pigs often experience growth reduction immediately after weaning due to multiple stress factors associated with weaning. We tested the effect of prenatal and postnatal butyrate supplementation on growth performance of piglets. In study 1, piglets were orally gavaged with 0.3% butyrate from day 4 after birth to weaning (day 21). Butyrate increased ADG by 13% compared to saline treated control. Expression of peroxisome proliferator activated receptor gamma coactivator 1 alpha (PGC-1α) was higher in muscle, adipose tissue, and ileum of butyrate-supplemented animals. Also, peroxisome proliferator activated receptor alpha (PPARα) was induced (P < 0.05) in the subcutaneous adipose tissue (SCAT) and muscle (longissimus dorsi [LD]) of butyrate-supplemented piglets. In vitro, butyrate increased (P < 0.05) fatty acid oxidation in primary adipocytes and suppressed basal lipolysis by 62% compared to untreated cells. Butyrate suppressed (P < 0.05) lipogenesis ((14)C-glucose incorporation into lipids) in adipocytes. This was accompanied by an approximately 30% reduction in the mRNA expression of fatty acid synthase (P < 0.05) in butyrate-treated cells vs. controls. Piglets born to sows that were supplemented with 0.3% butyrate during the last trimester of gestation had a 15% higher (P < 0.05) body weight at 12 wk than controls. In summary, butyrate supplementation to gestating sows and piglets enhanced postweaning growth performance, which may be mediated by increased substrate oxidation in butyrate treated animals.

Regulation of pre-adipocyte proliferation and apoptosis by the small leucine-rich proteoglycans, biglycan and decorin.

Evidence for a functional role for extracellular matrix (ECM) proteins in adipose tissue is demonstrated in dynamic changes in expression of ECM genes during adipocyte differentiation and in obesity. Components of the ECM may regulate adipose cell number expansion by restricting pre-adipocyte proliferation, regulating apoptosis and inhibiting adipogenesis. Although pre-adipocytes express multiple proteoglycans, their role in pre-adipocyte proliferation up to now has remained unknown. The study described here was conducted to characterize roles of small leucine-rich proteoglycans (SLRPs) in adipocyte proliferation. Pre-adipocytes were seeded on plates coated with biglycan and decorin and were allowed to differentiate. In addition, pre-adipocytes were incubated on plates coated with biglycan, decorin, or fibronectin and measurements were made of cell proliferation and apoptosis. We are able to report that SLRPs decorin and biglycan did not affect differentiation of our 3T3-L1 cells; however, biglycan and decorin did reduce proliferation of pre-adipocytes, partly by induction of apoptosis. Furthermore, anti-proliferative capabilities of decorin and biglycan were nullified with removal of GAG side-chains suggesting that the chains played key roles in anti-proliferative effects of the SLRPs. We also found that co-treatment of decorin or biglycan with the proteoglycan fibronectin restored normal proliferation, an indication that multiple ECM proteins may act in concert to regulate overall proliferation rates of pre-adipocytes. These studies indicate that SLRPs may compose a regulatory factor in adipose tissue expansion, through hyperplasia.

Perspectives on the formation of an interdisciplinary research team.

As research funding becomes more competitive, it will be imperative for researchers to break the mentality of a single laboratory/single research focus and develop an interdisciplinary research team aimed at addressing real world challenges. Members of this team may be at the same institution, may be found regionally, or may be international. However, all must share the same passion for a topic that is bigger than any individual's research focus. Moreover, special consideration should be given to the professional development issues of junior faculty participating in interdisciplinary research teams. While participation may be "humbling" at times, the sheer volume of research progress that may be achieved through interdisciplinary collaboration, even in light of a short supply of grant dollars, is remarkable.