T. A. T. G. van Kempen

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.

Lactulose as a marker of intestinal barrier function in pigs after weaning

Intestinal barrier function in pigs after weaning is almost exclusively determined in terminal experiments with Ussing chambers. Alternatively, the recovery in urine of orally administered lactulose can be used to assess intestinal permeability in living animals. This experiment was designed to study the barrier function of the small intestine of pigs over time after weaning. The aim was to relate paracellular barrier function (measured by lactulose recovery in the urine) with macromolecular transport [measured by horseradish peroxidase (HRP) using Ussing chambers] and bacterial translocation to assess whether lactulose recovery is related to possible causes of infection and disease. Forty gonadectomized male pigs (6.7 ± 0.6 kg) were weaned (d 0) at a mean age of 19 d, fitted with urine collection bags, and individually housed. Pigs were dosed by oral gavage with a marker solution containing lactulose (disaccharide) and the monosaccharides l-rhamnose, 3-O-methylglucose, and d-xylose at 2 h and at 4, 8, and 12 d after weaning. The recovery of sugars in the urine was determined over 18 h after each oral gavage. The day after each permeability test, the intestines of 10 pigs were dissected to determine bacterial translocation to the mesenteric lymph nodes and jejunal permeability for HRP in Ussing chambers. Recovery of l-rhamnose in urine was affected by feed intake and by the time after weaning (P ≤ 0.05). Recovery of lactulose from the urine was greater (P ≤ 0.05) at 4, 8, and 12 d after weaning compared with the first day after weaning and was negatively correlated with feed intake (r = -0.63, P ≤ 0.001). The mean translocation of aerobic bacteria to the mesenteric lymph nodes was greater at 5 and 13 d after weaning compared with d 1 (P ≤ 0.05). Lactulose recovery showed no correlation with permeability for HRP nor with bacterial translocation (P > 0.05). Although both lactulose recovery and bacterial translocation increased over time after weaning, lactulose recovery did not correlate with the permeability for HRP nor bacterial translocation within a pig (P > 0.05). Therefore, we conclude that lactulose recovery in the urine of pigs after weaning is not associated with risk factors for infections. However, it appears to be possible to measure paracellular barrier function with orally administered lactulose in pigs shortly after weaning. Further studies will reveal whether this variable is relevant for the long-term performance or health of pigs after weaning.

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.

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 β-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.

SWINE HOUSING WITH A BELT FOR SEPARATING URINE AND FECES; KEY TO FLEXIBILITY

Modern swine facilities have not been designed for maximization of manure value or minimization of ammonia emission. These benefits can possibly be achieved by harvesting urine and feces separately on a conveyor belt placed at a 4° angle beneath the slats. Urine drains off this belt into a gutter leading to a closed storage vessel while feces remain on the belt. Such a belt was evaluated in a partially slatted swine facility housing 80 grower pigs. Through the use of play-chains in the corners, solid pen partitions around the solid floor, and open partitions around the slatted floor, defecation behavior was directed to the slats. In trial 1, the optimal time of day for fecal collection, and belt performance under steady state use were determined. In trial 2, belt performance under steady state operation was tested, and animal performance was compared with that from a conventional facility. The belt system was timer-operated requiring no labor other than cleaning the scraper. Collections at 6 am resulted in a 10% increase in dry matter over 6 pm. During steady-state collections at 6 am, dry matter (DM) was 52±10% and 54±9% in trials 1 and 2, respectively, and 17% of feed DM was recovered as fecal DM (0.24 kg fecal DM/pig/day). Urine collections in trial 2 averaged 1.5±0.4 l/day or 42% of the water intake. Ammonia emissions were derived solely from the pen surface (unaffected by the fecal load on the belt), and thus were dependent on the defecation pattern of the animals. When defecation occurred predominantly on the slatted portion of the pen, ammonia emission was 1.0±0.2 kg per pig place per year. Pigs housed in the belt facility (trial 2) had a 6% improved feed efficiency compared to those in conventional housing. In conclusion, the belt housing system was easy to operate, resulted in good animal performance, and most importantly, yielded feces of 53% dry matter, a clean urine stream, and only 1 kg ammonia emissions per pig place per year.

MANIPULATION OF ANIMAL DIETS TO AFFECT MANURE PRODUCTION, COMPOSITION AND ODORS: STATE OF THE SCIENCE

Manure is composed of feces, bedding, wasted feed, and runoff water. Most of manure nutrients come from urine and feces excreted from animals that contain undigested components from their diets, excretion end products from normal metabolism, and bacterial cells from indigenous bacteria in the digestive tract. The amount and composition of freshly excreted manure can vary and is primarily influenced by the original composition of the diet. Diet ingredient sources, forms and levels can influence nutrient availability, excretion levels and forms. Because ruminants (including beef cattle and dairy cattle in this paper) have different digestive systems compared to nonruminants (including poultry and swine in this paper) excreta volume and composition differs. The digestive tract of a ruminant includes a multi (4)-compartment stomach that possesses a microbial population capable of digesting and releasing nutrients from highly fibrous feeds (forages) or highly digestible grains for the animal’s use. The nonruminant has a simple stomach (one compartment) that does not efficiently digest highly fibrous feeds, but requires highly digestible grains readily digested by enzymes to release nutrients for the animal’s use. Understanding the bioavailability of nutrients from feed sources used in the diets is critical for formulating a diet that will meet the productive needs of the animal. Feed management practices can also influence the efficiency of nutrient utilization in livestock and poultry operations. Odorous and gaseous compounds are emitted immediately after excretion due to microbial metabolism in the digestive tract of the animal. Further decomposition during storage can occur resulting in gaseous emissions and odors that have an impact on air quality. Since the animal is the initial source of nutrient excretions and odors from animal operations, diet manipulation is a practical and economical way to control excess nutrient excretions and reduce gaseous emissions. This paper summarizes key research approaches and results related to using diet manipulation to reduce nutrient excretions and minimize odors from livestock and poultry operations. In addition, this paper identifies some information gaps and needed research to fill the voids in information to maintain livestock and poultry production while sustaining environmental stewardship.

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.

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.

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.