Feed intake patterns nor growth rates of pigs are affected by dietary resistant starch, despite marked differences in digestion.

Current feed evaluation systems often assume that fermented starch (i.e. resistant starch (RS)) yields less energy than digested starch. However, growth rates of pigs fed low and high RS diets are often the same when feed is available ad libitum. This may be explained by its effect on digestive processes changing feeding behavior, and consequently energy utilization. This study aims to investigate the effect of RS on nutrient digestion and digesta passage rate in pigs, in combination with its effect on feeding behavior and growth performance under ad libitum conditions. In experiment 1, 20 male pigs (40 ± 2.82 kg) were fed diets containing either 50% waxy maize starch (low in RS (LRS)) or high-amylose maize starch (high in RS (HRS)), and soluble and insoluble indigestible markers. After 14 days of adaptation to the diets, pigs were fed hourly to reach steady state (6 h), dissected, and digesta were collected from eight segments. From the collected samples, nutrient digestion and passage rate of the solid and liquid digesta fraction were determined. In experiment 2, 288 pigs (80 ± 0.48 kg; sex ratio per pen 1 : 1; boar : gilt) were housed in groups of 6. Pigs were ad libitum-fed one of the experimental diets, and slaughtered at approximately 115 kg. Feed intake, growth and carcass parameters were measured. Ileal starch digestibility was greater for LRS-fed than for HRS-fed pigs (98.0% v. 74.0%; P < 0.001), where the additional undigested starch in HRS-fed pigs was fermented in the large intestine. No effects of RS on digesta passage rate of the solid or liquid digesta fraction and on feeding behavior were observed. Growth rate and feed intake did not differ between diets, whereas feed efficiency of HRS-fed pigs was 1%-unit higher than that of LRS-fed pigs (P = 0.041). The efficiency of feed used for carcass gain did not differ between diets indicating that the difference in feed efficiency was determined by the non-carcass fraction. Despite a 30% greater RS intake (of total starch) with HRS than with LRS, carcass gain and feed efficiency used for carcass gain were unaffected. RS did not affect digesta passage rate nor feeding behavior suggesting that the difference in energy intake between fermented and digested starch is compensated for post-absorptively. Our results indicate that the net energy value of fermented starch currently used in pig feed evaluation systems is underestimated and should be reconsidered.

Dietary fibre enrichment of supplemental feed modulates the development of the intestinal tract in suckling piglets.

BACKGROUND: Commercial pre-weaning diets are formulated to be highly digestible and nutrient-dense and contain low levels of dietary fibre. In contrast, pigs in a natural setting are manipulating fibre-rich plant material from a young age. Moreover, dietary fibre affects gastrointestinal tract (GIT) development and health in older pigs. We hypothesised that supplemental diets that contain vegetal fibres are accelerating GIT development in suckling piglets in terms of size and functionality. From d 2 of life, sow-suckled piglets had access to a low fibre diet (CON), a diet with a fermentable long-chain arabinoxylan (lc-AXOS), a diet with a largely non-fermentable purified cellulose (CELL), or a diet containing both fibres. During the initial 2 weeks, the control diet was a high-density milk replacer, followed by a dry and highly digestible creep meal. Upon weaning at 25 d, 15 piglets from each treatment group, identified as eaters and originating from six or seven litters, were sacrificed for post-mortem examination of GIT morphology, small intestinal permeability and metabolic profile of the digesta. The microbiota composition of the mid-colon was evaluated in a sub-set of ten piglets. RESULTS: No major statistical interactions between the fibre sources were observed. Piglets consumed the fibre-containing milk supplements and creep diets well. Stomach size and small intestinal permeability was not affected. Large intestinal fill was increased with lc-AXOS only, while relative large intestinal weight was increased with both fibre sources (P < 0.050). Also, CELL decreased ileal pH and tended to increase ileal DM content compared to CON (P < 0.050). Moreover, the concentration of volatile fatty acids was increased in the caecum (P < 0.100) and mid-colon (P < 0.050) by addition of CELL. lc-AXOS only stimulated caecal propionate (P < 0.050). The microbiota composition showed a high individual variation and limited dietary impact. Nonetheless, CELL induced minor shifts in specific genera, with notable reductions of Escherichia-Shigella. CONCLUSIONS: Adding dietary fibres to the supplemental diet of suckling piglets altered large intestinal morphology but not small intestinal permeability. Moreover, dietary fibre showed effects on fermentation and modest changes of microbial populations in the hindgut, with more prominent effects from the low-fermentable cellulose.

Vitamin E plasma kinetics in swine show low bioavailability and short half-life of -α-tocopheryl acetate.

Vitamin E is important for animal production because of its effects on health and product quality, but the amount and form required remains controversial. Our objective was to quantify the absolute bioavailability of oral -α-tocopheryl acetate (α-TAc) in swine (22 ± 1 kg and 8 wk old, fitted with jugular catheters) adapted to a diet supplemented with 75 mg/kg -α-TAc; 75 mg/kg was chosen because this level represents the nonweighted average inclusion level in piglet diets across Western key swine-producing countries. For this, a 350-g test meal (6% fat) was supplied at time 0 containing 75 mg deuterated (D9) -α-TAc to 9 animals, and 8 animals received an intravenous () dose containing deuterated (D6) RRR-α-tocopherol (α-T) at one-eighth the oral dose and a test meal without supplemental vitamin E. Plasma samples (12 to 13 per animal) were obtained at incremental intervals over 75 h for analysis of deuterated α-T using liquid chromatography-tandem mass spectrometry. Surprisingly, the i.v. dose rapidly disappeared from plasma and then reappeared. The half-life for this first peak was only 1.7 ± 0.3 min. The second peak had an appearance rate (Ka) of 0.10 ± 0.06 d and a half-life of 5.9 ± 1.2 h. Oral dosing resulted, after a lag of 56 min, in a Ka of 0.91 ± 0.21 d and a half-life of 2.6 ± 0.8 h. The bioavailability for oral α-TAc was 12.5%, whereas the area under the curve was only 5.4%. This low bioavailability, small area under the curve, and short half-life are likely because of various factors, that is, the use of only 6% fat in the diet, the use of the acetate ester and , and the high dose relative to requirements. In conclusion, i.v. dosed vitamin E shows both a rapid and a very slow pool, whereas orally dosed vitamin E shows a single slow pool. The oral material has a very short half-live (44% of i.v. or 2.6 h), low bioavailability (12.5%), and a very small area under the curve (5.4%), bringing into question the efficacy of typical doses of vitamin E in swine diets for alleviating oxidative stress.

Sex differences in NMDA GluN1 plasticity in rostral ventrolateral medulla neurons containing corticotropin-releasing factor type 1 receptor following slow-pressor angiotensin II hypertension.

There are profound, yet incompletely understood, sex differences in the neurogenic regulation of blood pressure. Both corticotropin signaling and glutamate receptor plasticity, which differ between males and females, are known to play important roles in the neural regulation of blood pressure. However, the relationship between hypertension and glutamate plasticity in corticotropin-releasing factor (CRF)-receptive neurons in brain cardiovascular regulatory areas, including the rostral ventrolateral medulla (RVLM) and paraventricular nucleus of the hypothalamus (PVN), is not understood. In the present study, we used dual-label immuno-electron microscopy to analyze sex differences in slow-pressor angiotensin II (AngII) hypertension with respect to the subcellular distribution of the obligatory NMDA glutamate receptor subunit 1 (GluN1) subunit of the N-methyl-D-aspartate receptor (NMDAR) in the RVLM and PVN. Studies were conducted in mice expressing the enhanced green fluorescence protein (EGFP) under the control of the CRF type 1 receptor (CRF1) promoter (i.e., CRF1-EGFP reporter mice). By light microscopy, GluN1-immunoreactivity (ir) was found in CRF1-EGFP neurons of the RVLM and PVN. Moreover, in both regions tyrosine hydroxylase (TH) was found in CRF1-EGFP neurons. In response to AngII, male mice showed an elevation in blood pressure that was associated with an increase in the proportion of GluN1 on presumably functional areas of the plasma membrane (PM) in CRF1-EGFP dendritic profiles in the RVLM. In female mice, AngII was neither associated with an increase in blood pressure nor an increase in PM GluN1 in the RVLM. Unlike the RVLM, AngII-mediated hypertension had no effect on GluN1 localization in CRF1-EGFP dendrites in the PVN of either male or female mice. These studies provide an anatomical mechanism for sex-differences in the convergent modulation of RVLM catecholaminergic neurons by CRF and glutamate. Moreover, these results suggest that sexual dimorphism in AngII-induced hypertension is reflected by NMDA receptor trafficking in presumptive sympathoexcitatory neurons in the RVLM.

Dietary adipic acid reduces ammonia emission from swine excreta.

Adipic acid is only partially catabolized when it is fed to animals, and a portion of it is excreted in urine. The excreted portion may lower urinary pH and, as a result, ammonia emission. The present study tested this hypothesis. In Exp. 1, nursery pigs (n = 14) were fed (for a period of 7 d) either a standard nursery diet or the same diet supplemented with 1% adipic acid to assess effects on urinary pH (collected on d 5 or 6) and in vitro ammonia emission from the collected urine samples that were mixed with control feces. In Exp. 2, grower pigs housed 10 each in one of two chambers were fed a control diet or the same diet supplemented with 1% adipic acid. Ventilated air was quantified and analyzed for ammonia using Fourier transform infrared spectroscopy to determine the effects of feeding 1% adipic acid on ammonia emission. The results from Exp. 1 showed that adipic acid strongly reduced urinary pH (from 7.7 to 5.5, P < 0.05). In vitro ammonia emission from these urine samples was significantly reduced at all the time points evaluated (1, 3, 18, and 46 h with reductions of 94, 93, 70, and 39%, respectively, P < 0.05). Experiment 2 showed that adipic acid supplementation reduced ammonia emission by 25% (P < 0.05), which corresponded to the predicted reduction in ammonia emission based on the reduction in manure pH observed. In conclusion, feeding adipic acid lowers urinary pH and reduces ammonia emission. The reduction in ammonia emission, though, does not correspond to the reduction in urinary pH but corresponds to the reduction in fecal pH as a result of mixing the urine and feces, in which feces act as a strong buffer.

Technical note: comparison of Raman, mid, and near infrared spectroscopy for predicting the amino acid content in animal meals.

The objective of this study was to compare three infrared spectroscopy techniques for routine evaluation of AA in animal meals. Animal meals (n = 54) with known AA contents were scanned with a near (NIRS), mid (FTIR), and Raman infrared spectrometer. For NIRS and Raman, samples were scanned "as is", whereas for FTIR, samples had to be finely ground before scanning to obtain reasonable spectra. Both FTIR and Raman data suffered from noise; for Raman, this prevented the development of calibrations. Using derivatized spectral data and a standardized outlier removal procedure, calibrations for nutritionally relevant AA could be developed that were equivalent for both NIRS and FTIR. The variation across AA tested explained (r2) by these calibrations was 70% for NIRS and 68 + 3% for FTIR. Removing spectral data between 4,000 and 2,000 cm(-1) from the FTIR data improved calibrations (P = 0.09) and explained an average of 77% of the variation with prediction errors lower than obtained with NIRS (P < 0.01). However, FTIR calibrations based on the entire or the shortened spectrum contained fewer samples than did NIRS calibrations (41 and 39 vs. 48, respectively; P < 0.01) because more samples were removed as outliers. In conclusion, Raman did not yield acceptable spectra for animal meals. For FTIR, sample preparation was more time-consuming because the samples required grinding before analysis. Using the entire mid-infrared range, FTIR calibrations were comparable to NIRS calibrations. Calibrations for FTIR were improved by eliminating wave numbers that exhibited more noise, resulting in prediction errors better than those for NIRS. Thus, FTIR has the potential to yield better calibrations for AA in animal meals than NIRS, but it requires greater care in sample preparation and scanning.

Adipic acid increases plasma lysine but does not improve the efficiency of lysine utilization in swine.

Adipic acid, upon catabolism, results in intermediates that bear a structural similarity to lysine degradation products. The objectives of this research were to determine whether adipic acid affects lysine concentrations in plasma and to evaluate whether adipic acid improves the efficiency of lysine utilization in pigs. In Exp. 1, nursery pigs (n = 14) were fed (for a period of 7 d) either a standard nursery diet or the same diet supplemented with 1% adipic acid to assess effects on plasma amino acid concentrations (plasma collected on d 7). In Exp. 2, nursery pigs (n = 56) were fed (for a period of 15 d) either a control diet or the same diet but deficient in either lysine, threonine, or tryptophan with or without supplemental adipic acid to assess the effects of adipic acid on the efficiency of amino acid utilization. The results from Exp. 1 showed that adipic acid increased plasma lysine (by 18%) but not alpha-amino adipic acid, an intermediate in lysine degradation. Experiment 2 demonstrated that adipic acid did not increase the efficiency of utilization of lysine, threonine, or tryptophan. The lack of effects on alpha-amino adipic acid in Exp. 1 and the lack of a positive effect on the efficiency of utilization of lysine, threonine, and tryptophan suggest that adipic acid does not inhibit the mitochondrial uptake of lysine and(or) its degradation in the mitochondrion. It is concluded that feeding adipic acid increases plasma lysine but does not improve the efficiency of lysine utilization.

Growth performance, carcass characteristics, nutrient digestibility and fecal odorous compounds in growing-finishing pigs fed diets containing hydrolyzed feather meal.

This study was designed to determine the effects of hydrolyzed feather meal inclusion on growth performance, carcass characteristics, nutrient digestibility and fecal odorous compounds in modern lean growth genotype pigs. Two hundred forty pigs (BW = 23.2 +/- 1.3 kg) were allotted based on BW and sex to a 2 x 6 factorial arrangement of treatments (four pens per treatment; five pigs per pen) in a randomized complete block design. Factors consisted of 1) sex (barrows or gilts) and 2) dietary treatment (0, 2, 4, 6, 8, or 10% hydrolyzed feather meal). Diets were formulated to contain 1.00, 0.90, 0.75, or 0.60% apparent ileal digestible lysine for phases 1 to 4, respectively, with other amino acids provided at an ideal ratio. Available P and ME were kept constant within each phase. No significant interactions between feather meal inclusion and sex were observed for growth performance (P > 0.15). Body weight gain was reduced (P < 0.05) for pigs fed 10% feather meal compared to pigs fed 0, 4, or 8% feather meal. Feed intake of pigs fed 10% feather meal was reduced (P < 0.05) compared to pigs fed 0 or 4% feather meal. Ultrasound backfat measurements tended (P = 0.12) to increase with increasing levels of feather meal. Daily lean gain was less (P < 0.05) in pigs fed 10% feather meal than in pigs fed either 0, 2, 4, or 8% feather meal. Digestibility of N measured on wk 9 decreased quadratically (P < 0.001) with increasing levels of feather meal. Phosphorus digestibility increased in a linear fashion (P < 0.02), however, the improvement in P digestibility with increasing levels of feather meal was more pronounced in barrows compared to gilts (interaction, P < 0.05). Fecal samples obtained from pigs fed 0, 4, or 8% feather meal were analyzed for odorous compounds. Concentrations of butanoic, pentanoic, and 3-methylbutanoic acid were greater (P < 0.05) and concentrations of 3-methylphenol, 4-methylphenol, indole, and decane were less (P < 0.05) in feces from pigs fed feather meal. These results suggest that feather meal can be included in diets for growing-finishing pigs at a rate of 8%. Excretion of N in feces increased but P excretion decreased with increasing levels of feather meal. Odorous compounds in feces can be affected by the inclusion of hydrolyzed feather meal, but the exact impact of these changes on odor perception remains to be elucidated.

Refining in vitro digestibility assays: fractionation of digestible and indigestible peptides.

Typically, in vitro methods used for estimating the amount of ileal digestible AA do not exhaustively digest samples, and arbitrary methods for separating digestible from indigestible protein are used. This may lead to over- or underestimation of digestibility coefficients. A method that exhaustively digests proteins using pepsin and pancreatin was developed, and the first objective of this research was to confirm that exhaustive digestion was indeed appropriate and to determine the fractionation method for separating digestible from indigestible proteins. For this, three homoarginine-labeled animal proteins were prepared. Samples were subsequently digested in vivo and in vitro to determine which fraction should be considered indigestible, and in vitro followed by in vivo to determine whether the extent of digestion in vivo was improved by predigestion. In vivo, soluble but unabsorbed peptides were smaller than 1 kDa, suggesting that the size of soluble peptides is not what prevents their absorption. Thus, all in vitro-soluble proteins should be considered digestible. In vitro, 88 +/- 3% of the soluble peptides were smaller than 1 kDa, with the remainder between 1 and 5 kDa, suggesting that in vitro digestion is less complete. Predigested samples were digested in vivo to the same size distribution as the nonpredigested samples. The second objective was to test whether in vitro digestibility assays based on these principles equaled in vivo digestibility. For this, digestibility data for 25 animal proteins were compared. Results showed a lack of correlation between lysine digestibility coefficients; however, across samples, the extent of digestion did not differ for lysine (P = 0.71), threonine (P = 0.26), methionine (P = 0.18), or valine (P = 0.66), whereas in vitro digestibility coefficients were lower for (the less water-soluble) histidine (P = 0.05), isoleucine (P < 0.01), leucine (P < 0.01), and phenylalanine (P = 0.05). In conclusion, in vitro digestibility assays should exhaustively digest proteins to mimic in vivo digestibility. All in vitro-soluble peptides could be considered digestible, because in vivo, no large soluble peptides were observed whose size prevented them from being absorbed. However, an in vitro assay based on these principles lacked precision for highly water-soluble AA, and underestimated digestibility for other AA. Better solubilization of the digesta and more replicates may improve the in vitro assay further.

Technical note: fourier transform infrared (FTIR) spectroscopy as an optical nose for predicting odor sensation.

Quantifying odor is important for objectively assessing the impact of animal production systems on surrounding areas. A possible method that has received little attention is Fourier transform (mid) infrared spectroscopy (FTIR). Gases that contribute to odor have unique infrared spectra, and the advantage of FTIR over electronic nose technology or gas chromatography is that theoretically all these gases can be analyzed instantaneously. To determine the feasibility of FTIR for predicting odor, 71 air samples analyzed by olfactometry were scanned in a spectrometer using an 84-m path-length gas cell. Scans were obtained over a period of about 1 min and from 4,000 to 740 cm(-1) with a resolution of 0.5 cm(-1). Calibrations for predicting odor were developed using partial least squares regression with full cross-validation. Air samples were obtained from experiments with pigs fed diets formulated to alter odor emission or from stored manure. Odor threshold dilution ratios averaged 676+/-491 units, with a range from 120 to 2,161. Using these samples, a prediction error for odor sensation of 344 units (R2 = 0.51) was obtained. Log transformation of the odor data improved the R2 to 0.61. Based on the olfactometry data, it is estimated that the measurement error of olfactometry is 250 units, which limits the R2 of any method to approximately 0.74. Thus, this calibration is very encouraging. In conclusion, FTIR shows promise as a practical means for objectively assessing swine odor.

Diet and evaluators affect perception of swine waste odor: an educational demonstration.

An educational program was developed for extension agents, faculty, and graduate students to illustrate the effect of diet composition on odor from swine manure. Participants in this program first received a 2-h detailed review on odorous compounds in manure and the effect of diet on odor. For the second portion of the training, nine manure samples were used from pigs fed diets formulated with feed ingredients predicted to have different effects on odor emission or a nutritionally adequate corn-soybean meal diet. Participants were instructed to rate the odor from these samples for pleasantness, irritation, and intensity on a scale of 0 (best) to 8 (worst), using manure from the corn-soybean meal fed pig as the reference with a score defined as 4 for each variable. Results obtained were summarized and discussed before concluding the program. Participants were Cooperative Extension Agents (n = 13) with swine responsibilities and graduate students and faculty (n = 8). The manure from the diet with the worst odor scores (1% garlic) was rated at 70% more odorous across the three odor variables (P < 0.05) than the diet with the least odorous manure (purified diet). Even though a reference sample was used, individual participants differed in their perception of irritation across samples (P < 0.05), ranging in average score across diets from 2.4 (moderately better than reference) to 5.0 (slightly worse than reference). With extension agents, a 1 to 7 scale (very interesting to not at all interesting) was used for evaluation of the training session. Participants found the material to be interesting (mean = 1.7, SD = 0.7) and the training exercise to be well organized and coherent in its presentation (mean = 1.8, SD = 0.7). Participants enjoyed this training and learned that differences in odor are achievable through altering diet composition, and that the response to swine odor depends on individual odor perception.

Regional and processor variation in the ileal digestible amino acid content of soybean meals measured in growing swine.

To assess differences in soybean meal quality related to region of production, researchers in Illinois, Kansas, North Carolina, The Netherlands, and Ohio collected four soybean meal samples processed locally at least 15 d apart. These samples were assayed for ileal amino acid digestibility by pigs using a common soybean meal and a soy protein concentrate as references, and a low-protein casein diet for determination of endogenous amino acid losses. Digestibility was determined at each university using seven barrows surgically fitted with ileal cannulas in a 7 x 7 Latin square design. The experimental diets contained 17% CP from the test material except for the low-protein casein diet. Animals were fed twice daily, 12 h apart, at a level of 45 g x kg(-0.75) BW for each meal. Following a 5-d adaptation period, ileal digesta were collected for two 12-h periods for 2 d to be used for determination of ileal digestibility. Variation in amino acid digestibility was very small among and within sites and was much smaller than variation in the concentration of amino acids. Among sites, samples from The Netherlands had less total and thus digestible lysine and methionine than the U.S. samples (P < 0.05). The soybean meals tested in this experiment were approximately 4% higher in amino acids than that reported in the NRC (1998). True (standardized) digestibilities, however, were very similar to NRC values except for cysteine and threonine, which were 5 and 3 percentage points lower in this experiment, respectively. In conclusion, soybeans grown in the United States and locally processed into soybean meal were very similar in nutritional composition. Soybean meals produced in The Netherlands were lower in lysine and methionine (P < 0.05) but had a digestibility similar to that produced in the United States.

Ad libitum feeding during the peripartal period affects body condition, reproduction results and metabolism of sows.

To overcome negative energy balance during the peripartal period of sows, an ad libitum feeding strategy (ADLIB) as alternative for commonly used restricted feeding (STANDARD, on average 3kg feed/day) was evaluated. Plasma metabolites and thyroid hormones, change of back fat thickness (BF), reproductive traits, and piglet performance were monitored. Voluntary feed intake of ADLIB sows declined at farrowing but was still more than twice the amount of what was offered to STANDARD sows. Consequently, ADLIB sows lost less BF than STANDARD sows (P=0.041). Additionally, BF change was affected by body condition. LEAN sows (BF<18mm on d 105 of gestation) lost less BF than MODERATE sows (18mm≤BF≤22mm) which lost less BF than FAT sows (BF>22mm) (P<0.001). Except for a decreased percentage of stillborn piglets for MODERATE sows (P=0.044), reproduction results were not affected. Piglet weaning weight of ADLIB-FAT and STANDARD-MODERATE sows was reduced in comparison with that of ADLIB-LEAN sows (P=0.005). Regardless of body condition, all metabolites and thyroid hormones measured showed a time dependent profile (P<0.001). On d 112 of gestation increased concentrations of creatinine (P=0.004), non-esterified fatty acids (P=0.039), and serum crosslaps (P=0.016) for STANDARD sows were observed. Triglycerides were increased for FAT sows (P<0.001), and decreased faster over time for ADLIB (P=0.013) and for FAT (P=0.012). Although ad libitum feeding during the peripartal period only resulted in less mobilization of muscle, fat, and bone reserves on d 112 of gestation, results of BF change and piglet weaning weight indicated that ad libitum feeding is beneficial for sow performance provided that BF is below 22mm.

Identifying the limitations for growth in low performing piglets from birth until 10 weeks of age.

The evolution of hyper-prolific pig breeds has led to a higher within-litter variation in birth weight and in BW gain during the nursery phase. Based on an algorithm developed in previous research, two populations from a pool of 368 clinically healthy piglets at 6 weeks of age were selected: a low (LP) and a high (HP) performing population and their development was monitored until the end of the nursery phase (10 weeks of age). To understand the cause of the variation in growth between these populations we characterized the LP and HP piglets in terms of body morphology, behaviour, voluntary feed intake, BW gain, and apparent total tract and ileal nutrient digestibility. Piglets were housed individually and were fed a highly digestible diet. At selection, 6 weeks of age, the BW of LP and HP piglets were 6.8±0.1 and 12.2±0.1 kg, respectively. Compared with the LP piglets the HP piglets grew faster (203 g/day), ate more (275 g/day) from 6 to 10 weeks of age and were heavier at 10 weeks (30.0 v. 18.8 kg, all P<0.01). Yet, the differences in average daily gain and average daily feed intake disappeared when compared per kg BW0.75. Assuming similar maintenance requirements per kg BW0.75 the efficiency of feed utilization above maintenance was 0.1 g/g lower for the LP piglets (P=0.09).The gain : feed ratio was similar for both groups. LP piglets tended to take more time to touch a novel object (P=0.10), and spent more time eating (P<0.05). At 10 weeks, LP piglets had a higher body length and head circumference relative to BW (P<0.01). Relative to BW, LP had a 21% higher small intestine weight; 36% longer length, and relative to average FI, the small intestinal weight was 4 g/kg higher (both P=<0.01). Apparent total tract and ileal dry matter, N and gross energy digestibility were similar between groups (P>0.10). We concluded that the low performance of the LP piglets was due to their inability to engage compensatory gain or compensatory feed intake as efficiency of nutrient utilization and feed intake per kg BW0.75 was unaffected. LP piglets tend to be more fearful towards novel objects. The morphological comparisons, increased body length and head circumference relative to BW imply that LP piglets have an increased priority for skeletal growth.

Behavioral effects of repeated handling differ in rats reared in social isolation and environmental enrichment.

The post-weaning social environment has profound effects on behavior and physiology in rodents. Social isolation increases anxiety-like behaviors and novelty-induced locomotor activity, while environmental enrichment decreases these behaviors. In some cases, the effects of social isolation are ameliorated by repeated handling. The goal of the present study was to determine whether the effects of handling differ in rats reared in social isolation and those reared in an enriched environment. After weaning, male Long-Evans rats were housed individually (ISO)(3) or in groups in an enriched environment (EE). During adulthood, rats from each housing condition received four, once-daily, brief handling sessions or remained undisturbed in the home cage. All rats were then tested in the open field, elevated plus maze, and for behavioral responses to d-amphetamine (1.0mg/kg). EE rats spent more time on the open arms of the elevated plus maze and were more likely than ISO rats to emerge from the start box in the open field, suggesting lower anxiety. Handling significantly decreased open arm time in EE rats and marginally increased open arm time in ISO rats. Housing condition did not affect amphetamine-stimulated locomotor activity, but handling altered the time course of the amphetamine response. ISO rats exhibited significantly fewer stereotyped behaviors than did EE rats, but repeated handling eliminated this difference. These findings support previously published studies that suggest brief handling of adult rats may at least partially ameliorate the effects of post-weaning social isolation on anxiety-like behaviors and psychostimulant sensitivity. Furthermore, there are complex interactions between the effects of housing environment and handling, suggesting that handling may be perceived and/or processed differently, depending on the animal's housing environment.

Peripartum changes in orexigenic and anorexigenic hormones in relation to back fat thickness and feeding strategy of sows.

Highly prolific sows often experience peripartum hypophagia, resulting in decreased production rate. Leptin, ghrelin, and resistin are known as feed intake-regulating hormones in many species, but it is yet unknown how feeding strategy and body condition will affect these hormones around parturition in sows. In the present study, a total of 63 sows, parity 2 to 7 were divided over 2 treatment groups which were fed either restricted (RESTRICT) or ad libitum (ADLIB) during the peripartum period (day 106 of gestation until day 7 of lactation). Within each treatment group, sows were assigned to 1 of 3 body condition groups based on back fat thickness at day 106 of gestation: <18 mm (LEAN), between 18 and 22 mm (MODERATE), and >22 mm (FAT). Postprandial blood samples were taken on days 107, 109, and 112 of gestation and on days 1, 3, and 5 of lactation. With RIA, leptin, ghrelin, and resistin of each sample were analyzed. For both leptin and resistin, the hormonal profile gradually increased throughout the peripartum period (P < 0.001), whereas ghrelin peaked on day 109 of gestation compared with day 107 of gestation and day 1 of lactation. Other time points were intermediate between those two (P < 0.001). The peripartum profile of leptin was significantly higher for FAT sows than for the 2 other condition groups. No effect of body condition on ghrelin and resistin concentrations was observed. None of the 3 measured hormones were affected by feeding strategy. In conclusion, during the peripartum period feed intake of sows did not affect leptin, ghrelin, or resistin profiles. Leptin was the only hormone investigated that reflected body condition. Although body condition and late gestation feed intake have been previously described as risk factors for peripartum hypophagia, they did not induce hypophagia in any of the sows or affect the profile of the observed feed intake-regulating hormones during the peripartum period.

Starch and fiber properties affect their kinetics of digestion and thereby digestive physiology in pigs.

Traditionally in swine nutrition, analyses of starch and fiber have focused on assessing quantity; however, both have a wide range of functional properties making them underappreciated nutrients. Starch ranging from low to high amylose changes from rapidly digestible in the upper gut to poorly digestible but fermentable in the lower gut thereby changing from a source of glucose to VFA source. Likewise, fibers ranging from low to high viscosity affect digesta flow and from slowly to rapidly fermentable alter production of VFA serving as energy for the gut or whole body. Our hypothesis is that total extent, kinetics, and site of digestion or fermentation of starch and fiber are important for whole body nutrient use and intestinal health. To elucidate their effects, we developed in vitro, lab-based methodologies to describe kinetics of digestion and fermentation and linked these with in vivo models including i) ileum cannulation to collect digesta, ii) portal-vein catheterization to sequentially sample blood, iii) slaughter method to collect site-specific intestinal tissue and digesta, and iv) indirect calorimetry. Using these methods, kinetics of nutrient absorption was associated with pancreatic and intestinal hormones released into the portal vein, intestinal microbiota, and gene expression in intestinal tissue and microbiota. These studies confirmed that slowly digestible starch is partially degraded in the distal small and large intestine and fermented into VFA including butyrate (10-fold increase in net portal appearance), which reduces insulin responses by 60% and whole body energy use. Starch entering the distal intestine altered mRNA abundance of nutrient transporters and was bifidogenic. Extremely viscous purified fiber dampened glycemic responses and reduced digesta passage rate by 50% thereby increasing ileal digestion of dietary nutrients whereas increased fiber in feed grains reduced nutrient digestibility. Fermentable fiber increased butyrate and insulin production. These methods will therefore support elucidation of mechanisms that link starch and fiber properties to whole body nutrient use and intestinal health.

Slowly digestible starch influences mRNA abundance of glucose and short-chain fatty acid transporters in the porcine distal intestinal tract.

The relationship between starch chemistry and intestinal nutrient transporters is not well characterized. We hypothesized that inclusion of slowly instead of rapidly digestible starch in pig diets will decrease glucose and increase short-chain fatty acid (SCFA) transporter expression in the distal gut. Weaned barrows (n = 32) were fed 4 diets containing 70% starch [ranging from 0 to 63% amylose and from 1.06 (rapidly) to 0.22%/min (slowly) rate of in vitro digestion] at 3 × maintenance energy requirement in a complete randomized block design. Ileal and colon mucosa was collected on day 21 to quantify mRNA abundance of Na(+)-dependent glucose transporter 1 (SGLT1), monocarboxylic acid transporter 1 (MCT1), and Na(+)-coupled monocarboxylate transporter (SMCT). Messenger RNA was extracted and cDNA manufactured prior to relative quantitative reverse transcription PCR. Data were analyzed using the 2(-Δ ΔC)(T) method, with ß-actin and glyceraldehyde-3-phosphate dehydrogenase as reference genes, and regression analysis was performed. As in vitro rate of digestion decreased, SGLT1 linearly increased (P < 0.05) in the ileum. Contrary to SGLT1, MCT1 tended to linearly decrease (P = 0.08) in the ileum and increased quadratically (P < 0.001) in the colon with decreasing rate of digestion. Starch digestion rate did not affect SMCT in the ileum; however, colonic SMCT quadratically decreased (P < 0.01) with decreasing rate of digestion. In conclusion, in contrast to our hypothesis, slowly digestible starch increased ileal glucose and decreased ileal SCFA transporter mRNA abundance, possibly due to an increased glucose in the luminal ileum. Effects of starch on colonic SCFA transporter mRNA abundance were inconsistent.

Chenodeoxycholic acid reduces intestinal permeability in newly weaned piglets.

Piglets are highly susceptible to gut health-related problems. Intravenously administered chenodeoxycholic acid (CDCA) affects gut health mediated through glucagon-like peptide 2 (GLP-2). To test whether CDCA is a suitable feed additive for improving gut health, a trial was performed with newly weaned (21 d) piglets offered a diet with or without 60 mg CDCA/kg feed (n = 24/treatment). Upon weaning, piglets were fasted for 16 h and then intragastrically dosed with 20 g test feed in 40 g water. Subsequently, a jugular blood sample was taken on 45, 90, 135, or 180 min for analysis of GLP-2, peptide YY (PYY), and glucose. Afterwards, piglets were offered the experimental diets ad libitum. On days 3.5, 7.5, and 10.5 after weaning, serum responses to an intragastric dose of lactulose and Co-EDTA were tested at 2 h after dosing in 8 piglets per treatment. Immediately thereafter, piglets were euthanized, intestines were harvested, and permeability was measured ex vivo using the everted gut sac technique with 4 kDa fluorescein isothiocyanato (FITC)-dextran as marker at 25, 50, and 75% of the length of the small intestine. Dietary CDCA did not affect (P > 0.05) ADFI, ADG, G:F, blood glucose, and plasma GLP-2 and PYY. Serum cobalt and lactulose at day 10.5 tended to be lower in CDCA pigs compared with control pigs. Serum cobalt and lactulose concentrations were positively correlated (r = 0.67; P < 0.01). In conclusion, CDCA tended to reduce intestinal permeability at 10.5 d after weaning when fed to newly weaned piglets, implying that CDCA deserves further study as a means for improving intestinal health. The positive correlation found between Co-EDTA and lactulose indicates that both marker molecules measure similar change in permeability.

Distribution of angiotensin type 1a receptor-containing cells in the brains of bacterial artificial chromosome transgenic mice.

In the central nervous system, angiotensin II (AngII) binds to angiotensin type 1 receptors (AT(1)Rs) to affect autonomic and endocrine functions as well as learning and memory. However, understanding the function of cells containing AT(1)Rs has been restricted by limited availability of specific antisera, difficulties discriminating AT(1)R-immunoreactive cells in many brain regions and, the identification of AT(1)R-containing neurons for physiological and molecular studies. Here, we demonstrate that an Agtr1a bacterial artificial chromosome (BAC) transgenic mouse line that expresses type A AT(1)Rs (AT1aRs) identified by enhanced green fluorescent protein (EGFP) overcomes these shortcomings. Throughout the brain, AT1aR-EGFP was detected in the nuclei and cytoplasm of cells, most of which were neurons. EGFP often extended into dendritic processes and could be identified either natively or with immunolabeling of GFP. The distribution of AT1aR-EGFP cells in brain closely corresponded to that reported for AngII binding and AT1aR protein and mRNA. In particular, AT1aR-EGFP cells were in autonomic regions (e.g., hypothalamic paraventricular nucleus, central nucleus of the amygdala, parabrachial nucleus, nuclei of the solitary tract and rostral ventrolateral medulla) and in regions involved in electrolyte and fluid balance (i.e., subfornical organ) and learning and memory (i.e., cerebral cortex and hippocampus). Additionally, dual label electron microscopic studies in select brain areas demonstrate that cells containing AT1aR-EGFP colocalize with AT(1)R-immunoreactivity. Assessment of AngII-induced free radical production in isolated EGFP cells demonstrated feasibility of studies investigating AT1aR signaling ex vivo. These findings support the utility of Agtr1a BAC transgenic reporter mice for future studies understanding the role of AT(1)R-containing cells in brain function.