S. F. Liao

Effect of selenium-enriched probiotics on laying performance, egg quality, egg selenium content, and egg glutathione peroxidase activity.

A 35-day experiment was conducted to evaluate the effect of selenium-enriched probiotics (SP) on laying performance, egg quality, egg selenium (Se) content, and egg glutathione peroxidase (GPX) activity. Five hundred 58-week-old Rohman laying hens were randomly allotted to 5 dietary treatments of 100 each. Each treatment had 5 replicates, and each replicate had 5 cages with 4 hens per cage. The SP was supplemented to a corn-soybean-meal basal diet at 3 different levels that supplied total Se at 0.2, 0.5, and 1.0 mg/kg. The basal diet served as a blank control, while the basal diet with supplemental probiotics served as a probiotics control. The results showed that dietary SP supplementation not only increased (p < 0.05) the rate of egg laying, day egg weight, mean egg weight, egg Se content, and egg GPX activity but also decreased (p < 0.05) the feed:egg ratio and egg cholesterol content. The egg Se content was gradually increased (p < 0.05) along with the increasing level of dietary Se. The SP supplementation also slowed down (p < 0.05) the drop of Haugh units (HU) of eggs stored at room temperature. The egg GPX activity had a positive correlation (p < 0.01) with egg Se content and a negative correlation (p < 0.01) with egg HU drop. These results suggested that Se contents, GPX activity, and HU of eggs were affected by the dietary Se level, whereas the egg-laying performance and egg cholesterol content were affected by the dietary probiotics. It was concluded that this SP is an effective feed additive that combines the organic Se benefit for hen and human health with the probiotics benefit for laying hen production performance. It was also suggested that the eggs from hens fed this SP can serve as a nutraceutical food with high Se and low cholesterol contents for both healthy people and patients with hyperlipidemia, fatty liver, or cardiovascular disease.

Selenium-Enriched Probiotics Improve Antioxidant Status, Immune Function, and Selenoprotein Gene Expression of Piglets Raised under High Ambient Temperature

This research was conducted to evaluate the effects of selenium-enriched probiotics (SP) on growth performance, antioxidant status, immune function, and selenoprotein gene expression of piglets under natural high ambient temperature in summer. Forty-eight crossbred weanling piglets randomly allocated to four groups were fed for 42 days ad libitum a basal diet without (Con, 0.16 mg Se/kg) and with supplementation of probiotics (P, 0.16 mg Se/kg), sodium selenite (SS, 0.46 mg Se/kg), and SP (0.46 mg Se/kg). From each group, three piglets were randomly selected for blood collection on days 0, 14, 28, and 42 and tissue collection on day 42. The SP improved growth performance of piglets. Both SS and SP increased blood glutathione peroxidase activity and tissue thioredoxin reductase 1 mRNA expression, with SP being higher than SS. All P, SS, and SP supplementation increased the superoxide dismutase activity (40.1, 53.0, and 64.5%), glutathione content (84.6, 104, and 165%), TCR-induced T lymphocyte proliferation (20.8, 26.4, and 50.0%), and IL-2 concentration (24.9, 27.2, and 46.2%) and decreased malondialdehyde content (25.1, 26.3, and 49.3%), respectively. The greatest effects of SP supplementation suggest that SP may serve as a better feed additive than P or SS for piglets under high-temperature environments.

Ruminal and abomasal starch hydrolysate infusions selectively decrease the expression of cationic amino acid transporter mRNA by small intestinal epithelia of forage-fed beef steers

Although cationic amino acids (CAA) are considered essential to maximize optimal growth of cattle, transporters responsible for CAA absorption by bovine small intestinal epithelia have not been described. This study was conducted to test 2 hypotheses: 1) the duodenal, jejunal, and ileal epithelia of beef cattle differentially express 7 mRNA associated with 4 mammalian amino acid (AA) transport activities: y(+) (CAT1), B(0,+) (ATB(0,+)), b(0,+) (b(0,+)AT and rBAT), and y(+)L (y(+)LAT1, y(+)LAT2, and 4F2hc), and 2) the expression of these mRNA is responsive to small intestinal luminal supply of AA substrates (derived from ruminal microbes) or glucose-derived energy (from starch hydrolysate, SH), or both. Eighteen ruminally and abomasally catheterized Angus steers (body weight = 260 +/- 17 kg) fed an alfalfa cube-based diet at 1.33 x net energy for maintenance requirement were assigned to 3 treatments (n = 6): ruminal and abomasal water infusion (control); ruminal SH and abomasal water infusion; and ruminal water and abomasal SH infusion. The dosage of SH infusion amounted to 20% of metabolizable energy intake. After 14 or 16 d of infusion, steers were slaughtered, duodenal, jejunal, and ileal epithelia were harvested, and total RNA was extracted. The relative amounts of mRNA expressed by epithelia were quantified using real-time reverse transcription-PCR. All 7 mRNA species were expressed by the epithelium from each region, but their abundance differed among the regions. Specifically, duodenal expression of CAT1 and ATB(0,+) mRNA was greater than jejunal or ileal expression; ileal expression of b(0,+)AT, rBAT, and y(+)LAT1 mRNA was greater than jejunal or duodenal expression, whereas the expression of y(+)LAT2 and 4F2hc mRNA did not differ among the 3 epithelia. With regard to SH infusion effect, ruminal infusion down-regulated or tended to down-regulate the jejunal expression of CAT1, rBAT, y(+)LAT2, and 4F2hc mRNA. Abomasal infusion down-regulated the jejunal expression of y(+)LAT2 mRNA and tended to down-regulate the jejunal expression of 4F2hc mRNA. This study characterized the pattern of CAA transporter mRNA expressed by growing beef cattle fed an alfalfa-based diet. Moreover, this study demonstrated that increasing the luminal supply of microbe-derived AA (by ruminal supplementation of SH) results in a reduced capacity of apical and basolateral membrane to transport of CAA, whereas increasing luminal glucose supply (by abomasal supplementation of SH) reduces only the basolateral transport capacity, assuming that CAA transporter mRNA content represents functional capacity.

Metabolic acidosis in sheep alters expression of renal and skeletal muscle amino acid enzymes and transporters

To determine the effect of metabolic acidosis on expression of L-Gln, L-Glu, and L-Asp metabolizing enzymes and transporters, the relative content of mRNA, protein, or mRNA and protein, of 6 enzymes and 5 transporters was determined by real-time reverse transcription-PCR and immunoblot analyses in homogenates of kidney, skeletal muscle, and liver of growing lambs fed a common diet supplemented with canola meal (control; n = 5) or HCl-treated canola meal (acidosis; n = 5). Acidotic sheep had a 790% greater (P = 0.050) expression of renal Na(+)-coupled neutral AA transporter 3 mRNA and a decreased expression of renal glutamine synthetase mRNA (47% reduction, P = 0.037) and protein (57% reduction, P = 0.015) than control sheep. No change in renal cytosolic phosphoenolpyruvate carboxykinase (protein and mRNA), glutaminase (mRNA), or L-Glu dehydrogenase (protein) was found. In skeletal muscle, acidotic sheep had 101% more (P = 0.026) aspartate transaminase protein than did control sheep, whereas no change in the content of 3 Na(+)-coupled neutral AA transporters (mRNA) or 2 high-affinity L-Glu transporter proteins was found. In liver, no change in the content of any assessed enzyme or transporter was found. Collectively, these findings suggest that tissue-level responses of sheep to metabolic acidosis are different than for nonruminants. More specifically, these results indicate the potential capacity for metabolism of L-Asp and L-Glu by skeletal muscle, and L-Gln absorption by kidneys, but no change in hepatic expression of L-Gln metabolism, elaborates previous metabolic studies by revealing molecular-level responses to metabolic acidosis in sheep. The reader is cautioned that the metabolic acidosis model employed in this study differs from the increased plasma lactate-induced metabolic acidosis commonly observed in ruminants fed a highly fermentable grain diet.

The small intestinal epithelia of beef steers differentially express sugar transporter messenger ribonucleic acid in response to abomasal versus ruminal infusion of starch hydrolysate

In mammals, the absorption of monosaccharides from small intestinal lumen involves at least 3 sugar transporters (SugT): sodium-dependent glucose transporter 1 (SGLT1; gene SLC5A1) transports glucose and galactose, whereas glucose transporter (GLUT) 5 (GLUT5; gene SLC2A5) transports fructose, across the apical membrane of enterocytes. In contrast, GLUT2 (gene SLC2A2) transports all of these sugars across basolateral and apical membranes. To compare the distribution patterns and sensitivity with nutritional regulation of these 3 SugT mRNA in beef cattle small intestinal tissue, 18 ruminally and abomasally catheterized Angus steers (BW approximately 260 kg) were assigned to water (control), ruminal cornstarch (partially hydrolyzed by alpha-amylase; SH), or abomasal SH infusion treatments (n = 6) and fed an alfalfa-cube-based diet at 1.3 x NE(m) requirement. The SH infusions amounted to 20% of ME intake. After 14- or 16-d of infusion, steers were killed; duodenal, jejunal, and ileal epithelia harvested; and total RNA extracted. The relative amount of SugT mRNA in epithelia was determined using real-time reverse transcription-PCR quantification methods. Basal expression of GLUT2 and SGLT1 mRNA was greater (P < 0.09) by jejunal than by duodenal or ileal epithelia, whereas basal content of GLUT5 mRNA was greater (P < or = 0.02) by jejunal and duodenal than by ileal epithelia. The content of GLUT5 mRNA in small intestinal epithelia was not affected (P > or = 0.16) by either SH infusion treatment. In contrast, GLUT2 and SGLT1 mRNA content in the ileal epithelium was increased (P < or = 0.05) by 6.5- and 1.3-fold, respectively, after abomasal SH infusion. Duodenal SGLT1 mRNA content also was increased (P = 0.07) by 64% after ruminal SH infusion. These results demonstrate that the ileum of beef cattle small intestine adapts to an increased luminal supply of glucose by increasing SGLT1 and GLUT2 mRNA content, whereas increased ruminal SH supply results in duodenal upregulation of SGLT1 mRNA content. These adaptive responses of GLUT2 and SGLT1 mRNA to abomasal or ruminal SH infusion suggest that beef cattle can adapt to increase their carbohydrate assimilation through small intestinal epithelia, assuming that altered SugT mRNA contents reflect the altered transport functional capacities.

Lysine nutrition in swine and the related monogastric animals: muscle protein biosynthesis and beyond

Improving feed efficiency of pigs with dietary application of amino acids (AAs) is becoming increasingly important because this practice can not only secure the plasma AA supply for muscle growth but also protect the environment from nitrogen discharge with feces and urine. Lysine, the first limiting AA in typical swine diets, is a substrate for generating body proteins, peptides, and non-peptide molecules, while excess lysine is catabolized as an energy source. From a regulatory standpoint, lysine is at the top level in controlling AA metabolism, and lysine can also affect the metabolism of other nutrients. The effect of lysine on hormone production and activities is reflected by the change of plasma concentrations of insulin and insulin-like growth factor 1. Lysine residues in peptides are important sites for protein post-translational modification involved in epigenetic regulation of gene expression. An inborn error of a cationic AA transporter in humans can lead to a lysinuric protein intolerance condition. Dietary deficiency of lysine will impair animal immunity and elevate animal susceptibility to infectious diseases. Because lysine deficiency has negative impact on animal health and growth performance and it appears that dietary lysine is non-toxic even at a high dose of supplementation, nutritional emphasis should be put on lysine supplementation to avoid its deficiency rather than toxicity. Improvement of muscle growth of monogastric animals such as pigs via dietary lysine supply may be due to a greater increase in protein synthesis rather than a decrease in protein degradation. Nevertheless, the underlying metabolic and molecular mechanisms regarding lysine effect on muscle protein accretion merits further clarification. Future research undertaken to fully elucidate the metabolic and regulatory mechanisms of lysine nutrition could provide a sound scientific foundation necessary for developing novel nutritional strategies to enhance the muscle growth and development of meat animals.

Basal Expression of Nucleoside Transporter mRNA Differs Among Small Intestinal Epithelia of Beef Steers and Is Differentially Altered by Ruminal or Abomasal Infusion of Starch Hydrolysate

In ruminants, microbial-derived nucleic acids are a major source of N and are absorbed as nucleosides by small intestinal epithelia. Although the biochemical activities of 2 nucleoside transport systems have been described for cattle, little is known regarding the regulation of their gene expression. This study was conducted to test 2 hypotheses: (1) the small intestinal epithelia of beef cattle differentially express mRNA for 3 concentrative (CNT1, 2, 3) and 2 equilibrative (ENT1, 2) nucleoside transporters (NT), and (2) expression of these NT is responsive to small intestine luminal supply of rumen-derived microbes (hence, nucleosides), energy (cornstarch hydrolysate, SH), or both. Eighteen ruminally and abomasally catheterized Angus steers (260 +/- 17 kg of BW) were fed an alfalfa cube-based diet at 1.33x NE(m) requirement. Six steers in each of 3 periods were blocked by BW (heavy vs. light). Within each block, 3 steers were randomly assigned to 3 treatments (n = 6): ruminal and abomasal water infusion (control), ruminal SH infusion/abomasal water infusion, or ruminal water infusion/abomasal SH infusion. The dosage of SH infusion amounted to 20% of ME intake. After a 14-or 16-d infusion period, steers were slaughtered, and duodenal, jejunal, and ileal epithelia were harvested for total RNA extraction and the relative amounts of mRNA expressed were determined using real-time RT-PCR quantification methodologies. All 5 NT mRNA were found expressed by each epithelium, but their abundance differed among epithelia. Specifically, jejunal expression of all 5 NT mRNA was higher than that by the ileum, whereas jejunal expression of CNT1, CNT3, and ENT1 mRNA was higher, or tended to be higher, than duodenal expression. Duodenal expression of CNT2, CNT3, and ENT2 mRNA was higher than ileal expression. With regard to SH infusion treatments, ruminal infusion increased duodenal expression of CNT3 (67%), ENT1 (51%), and ENT2 (39%) mRNA and ileal expression of CNT3 (210%) and ENT2 (65%) mRNA. Abomasal infusion increased (54%) ileal expression of ENT2 mRNA and tended to increase (50%) jejunal ENT2 mRNA expression. This study has uniquely characterized the pattern of NT mRNA expression by growing beef cattle and found that the mRNA abundance for CNT3, ENT1, and ENT2 in small intestinal epithelia can be increased by increasing the luminal supply of nucleotides (CNT3, ENT1, ENT2) or glucose (ENT2).

Effects of dietary supplementation of selenium‐enriched probiotics on production performance and intestinal microbiota of weanling piglets raised under high ambient temperature

This study was designed to evaluate the efficacy of selenium-enriched probiotics (SeP) on production performance and intestinal microbiota of piglets raised under high ambient temperature. Forty-eight cross-bred weanling piglets (28 days old), randomly allotted into 12 pens (four piglets/pen) and four dietary treatments (three pens/treatment group), were fed ad libitum for 42 days a basal diet (Con) or the basal diet supplemented with probiotics (Pro), sodium selenite (ISe) or a SeP preparation. Blood and faecal samples were collected on days 0, 14, 28 and 42 post-treatment. The SeP group had higher final BW (p < 0.05), greater ADG (p < 0.05) and lower FCR (p < 0.01) than the Pro, ISe or Con group. The diarrhoea incidence rate of either SeP or Pro group was lower (p < 0.01) than the ISe or Con group. Blood Se concentration and GSH-Px activity were both higher (p < 0.01) in the SeP than in the Pro, ISe or Con group. On days 28 and 42, the serum concentrations of T3 were higher (p < 0.01) and T4 lower (p < 0.01) in the SeP than in the ISe group, and the T3 and T4 concentrations in the ISe group, in turn, were higher (p < 0.05) and lower (p < 0.01), respectively, than in the Pro or Con group. Also on days 28 and 42, the faecal counts of lactobacillus bacteria were higher (p < 0.01) while Escherichia coli lower (p < 0.01) in the SeP or Pro group as compared to the ISe or Con group. The results of RFLP showed that the faecal microbial flora in the SeP group changed the most (numerically) as compared to the Pro or ISe group. These results suggest that the SeP product may serve as a better alternative to antibiotics than the solo probiotics for using as a growth promoter for weanling piglets.

Feeding glycerol-enriched yeast culture improves performance, energy status, and heat shock protein gene expression of lactating Holstein cows under heat stress.

This study was conducted to evaluate the effects of supplemental common yeast culture (CY) and glycerol-enriched yeast culture (GY) on performance, plasma metabolites, antioxidant status, and heat shock protein 70 (HSP70) mRNA expression in lactating Holstein cows under heat stress. During summer months, 30 healthy multiparous lactating cows (parity 3.25 ± 0.48; 60 ± 13 d in milk [DIM]; 648 ± 57 kg BW; an average milk yield of 33.8 ± 1.6 kg/d) were blocked by parity, previous milk yield, and DIM and randomly allocated to 3 dietary treatments: no supplemental yeast culture (Control), 1 L/d of CY (33.1 g yeast) per cow, and 2 L/d of GY (153.2 g glycerol and 31.6 g yeast) per cow. During the 60-d experiment, values of air temperature and relative humidity inside the barn were recorded hourly every 3 d to calculate temperature-humidity index (THI). Weekly rectal temperatures (RT) and respiration rates and daily DMI and milk yield were recorded for all cows. Milk and blood samples were taken twice monthly, and BW and BCS were obtained on d 0 and 60. In this experiment, THI values indicated cows experienced a moderate heat stress. Cows supplemented with CY and GY had greater yields of milk, energy-corrected milk and milk fat, and milk fat percent but lower HSP70 mRNA expression in peripheral blood lymphocytes than Control cows (P < 0.05). Supplementing CY and GY tended (P < 0.15) to decrease RT at 1400 h, increase milk protein yield and erythrocyte glutathione, and reduce plasma urea nitrogen compared with Control. Lower plasma NEFA concentration and HSP70 mRNA expression in peripheral blood lymphocytes (P < 0.05) and tendencies towards greater plasma glucose concentration (P = 0.11) but less BW loss (P = 0.14) were observed in GY relative to CY cows. In conclusion, either CY or GY supplementation partially mitigated the negative effects of heat stress on performance and HSP70 mRNA expression of lactating cows, and GY supplementation provided additional improvements in energy status and HSP70 gene expression of lactating cows.

Bovine neuronal vesicular glutamate transporter activity is inhibited by ergovaline and other ergopeptines1

l-Glutamate (Glu) is a major excitatory neurotransmitter responsible for neurotransmission in the vertebrate central nervous system. Vesicular Glu transporters VGLUT1 and VGLUT2 concentrate (50mM) Glu [Michaelis constant (measuring affinity), or K(m),=1 to 4mM] into synaptic vesicles (SV) for subsequent release into the synaptic cleft of glutamatergic neurons. Vesicular Glu transporter activity is dependent on vacuolar H(+)-ATPase function. Previous research has shown that ergopeptines contained in endophyte-infected tall fescue interact with dopaminergic and serotoninergic receptors, thereby affecting physiology regulated by these neuron types. To test the hypothesis that ergopeptine alkaloids inhibit VGLUT activity of bovine cerebral SV, SV were isolated from cerebral tissue of Angus-cross steers that were naive to ergot alkaloids. Immunoblot analysis validated the enrichment of VGLUT1, VGLUT2, synaptophysin 1, and vacuolar H(+)-ATPase in purified SV. Glutamate uptake assays demonstrated the dependence of SV VGLUT-like activity on the presence of ATP, H(+)-gradients, and H(+)-ATPase function. The effect of ergopeptines on VGLUT activity was evaluated by ANOVA. Inhibitory competition (IC(50)) experiments revealed that VGLUT-mediated Glu uptake (n=9) was inhibited by ergopeptine alkaloids: bromocriptine (2.83±0.59μM)<ergotamine (20.5±2.77μM)<ergocornine (114±23.1μM)<ergovaline (137±6.55μM). Subsequent ergovaline kinetic inhibition analysis (n=9; Glu=0.05, 0.10, 0.50, 1, 2, 4, 5mM) demonstrated no change in apparent K(m). However, the maximum reaction rate (V(max)) of Glu uptake was decreased when evaluated in the presence of 50, 100, and 200μM ergovaline, suggesting that ergovaline inhibited SV VGLUT activity through a noncompetitive mechanism. The findings of this study suggest cattle with fescue toxicosis may have a decreased glutamatergic neurotransmission capacity due to consumption of ergopeptine alkaloids.