The effect of 25‐hydroxyvitamin D3 and phytase inclusion on pig performance,bone parameters and pork quality in finisher pigs

The objective of this study was to investigate the effects of supplementing both phytase and 25‐hydroxyvitamin D₃ (25‐OH ‐D?) on pig performance, nutrient digestibility, carcass characteristics, bone parameters and pork quality in finisher pigs. The experimental design was a 2 × 2 factorial comprising of four dietary treatments. One hundred and twenty pigs (60 male, 60 female) were blocked according to live weight and sex and allocated to the following dietary treatments: low P (4.81 g/kg) diet (basal) (T1); low P diet + phytase (T2); low P diet + 25‐OH ‐D? (T3) and low P diet + phytase + 25‐OH ‐D? (T4). Pigs supplemented with phytase had a lower average daily feed intake (ADFI ) (2.45 kg vs. 2.59 kg; p  < 0.05) and lower feed conversion ratio (FCR ) (2.74 kg/kg vs. 2.85 kg/kg; p  <  0.05) compared to pigs offered the nonphytase diets. Pigs offered phytase diets had a higher (p  <  0.05) coefficient of apparent total tract digestibility (CATTD ) of ash, phosphorous (P) and calcium (Ca) compared with pigs offered the nonphytase supplemented diets. Pigs offered the 25‐OH ‐D₃ diets had a higher CATTD of N and ash. Pigs offered the phytase diets had increased (p  <  0.05) bone DM , ash, Ca, P and density compared to the nonphytase diets. There was a significant interaction (p  <  0.05) between phytase and 25‐OH ‐D₃ on cook loss. Pigs offered 25‐OH ‐D₃ had increased cook loss over the basal diet; however, there was no effect on cook loss when phytase and 25‐OH ‐D₃ were offered in combination compared to the phytase only diet. Pigs offered 25‐OH ‐D₃ exhibited higher (p  <  0.05) Warner Bratzler shear force values and lower (p  <  0.05) pork lightness (L *) surface colorimeter values. In conclusion, there was no benefit to offering a combination of phytase and 25‐OH ‐D₃ on pig performance, bone parameters or pork quality.     

Assessment of the effect of grape seed cake inclusion in the diet of healthy fattening‐finishing pigs

Modulatory capacity of bioactive compounds from different wastes has been scarcely investigated in pigs. This study aimed to evaluate the effects of dietary inclusion of grape seed cakes (GS diet) on performance and plasma biochemistry parameters as health indicators, as well as on several markers related to inflammation and antioxidant defence in the liver of fattening‐finishing pigs. Twelve cross‐bred pigs (TOPIG ) were randomly assigned to one of two experimental diets: control and 5% grape seed cake diet during finishing period (24 days). No effect of GS diet on pig performance and blood biochemistry was observed. However, GS diet decreased significantly (?9.05%, p  <  .05) the cholesterol concentration (85.71 ± 0.94 mg/dl vs 94.24 ± 2.16 mg/dl) and increased IgA level (+49.90%, p  <  .05) in plasma (5.04 ± 0.5 mg/ml vs 3.36 ± 0.7 mg/ml). GS cakes decreased the inflammatory response in the liver of pigs fed with GS diet by lowering the Gene expression and protein concentration of pro‐inflammatory cytokines (IL ‐1β , IL ‐8, TNF ‐α and IFN ‐γ ) as well as the mRNA abundances of NF ‐κ B signalling molecules. The antioxidant status was not increased by GS diet. The gene expression and activity of catalase decreased significantly. The gene expression of Nrf2, superoxide dismutase, glutathione peroxidase and heat‐shock protein decreased, and no effect on their activity was observed with the exception of catalase activity which decreased. However, TBARS was reduced significantly. GS diet showed a modulatory effect on antioxidative status as well as anti‐inflammatory and hypocholesterolic properties without effect on pig performance.     

Dietary exposure assessment of cyadox based on tissue depletion of cyadox and its major metabolites in pigs,chickens, and carp

The tissue kinetics of cyadox, an antibacterial agent used in food animals, and its major metabolites in pigs, chickens, and carp were investigated followed by a complete dietary exposure assessment to evaluate the food safety of cyadox. Cyadox and its major metabolites, bisdeoxycyadox (Cy1), 4‐desoxycyadox (Cy2), N ‐(quinoxaline‐2‐methyl)‐cyanide acetyl hydrazine (Cy4), quinoxaline‐2‐carboxylic acid (Cy6), and 2‐hydromethyl‐3‐hydroxy‐quinoxaline (Cy12), were simultaneously quantitated with a high‐performance liquid chromatography?ultraviolet (HPLC ‐UV ) method. Pigs, chickens, and carp were fed with 150 mg/kg cyadox in feed for consecutive 60, 40, and 30 days, respectively. The residue amount of cyadox and its major metabolites in liver, kidney, muscle, and fat (skin) tissues was determined. Cy2 was below the limit of quantitation even at the withdrawal time of 6 hr, cyadox, Cy4, Cy6, and Cy12 could be detected at 6–24 hr with low level less than 50 μg/kg. By contrast, Cy1 persisted for 3 days in the kidney of pigs and chickens, and in the liver of carp. Based on these residue depletion data and previous toxicology results, the global estimated chronic dietary exposure assessment of cyadox for general population was conducted, indicating a zero withdrawal time (WDT ) may be appropriate for cyadox in food animals when used in feed for prolonged administration. These results provide analytical techniques and safety standards suitable for residue monitoring of cyadox in food animals.     

Comparative studies on the effect of fenbendazole on the liver and liver microsomal enzymes in goats,quail and rats

To compare the effect of fenbendazole on the liver and liver microsomal mono-oxygenases of goats, quail and rats, an oral dose of 25 mg/kg was administered to the animals daily for 9 consecutive days. On the tenth day, blood samples and livers were collected from both the control and the treated animals for preparation of serum and microsomes respectively. Determination of the activities of sorbitol dehydrogenase (SDH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the serum samples showed that there was no significant increase in the activities of these enzymes in the treated animals as compared to their corresponding controls, suggesting no liver damage. Similarly, no significant difference in the amount of microsomal cytochrome P-450 was found between the control and the treated animals of the same species. Compared to their respective controls, the activities of microsomal benzphetamine N-demethylase and aniline hydroxylase were almost unchanged in the treated goats and rats. However, fenbendazole treatment appeared to enhance the activity of these two microsomal enzymes in quail. The results indicate that fenbendazole is not liver toxic to goats, quail or rats at a dose rate of 25 mg/kg.     

Impact of age on hepatic cytochrome P450 of domestic male Camborough‐29 pigs

Swine is not only an important species in veterinary medicine research but also a popular animal model for human drug discovery. It is valuable to understand the impact of pig age on abundance and activity of porcine hepatic cytochrome P450 (CYP450). Liver microsomes were prepared from Camborough‐29 intact male pigs at the age of 1 day and 2 weeks and the castrated male pigs at the age of 5, 10, and 20 weeks. Hepatic CYP450 content in the liver microsomes was measured using a UV/visible spectroscopic method. The activities of CYP450s were evaluated by metabolism of phenacetin, coumarin, tolbutamide, bufuralol, chlorzoxazone, and midazolam. The porcine hepatic CYP450 content increased with age with a plateau between age 2 and 5 weeks. Activities of all CYP450 enzymes increased with age of pigs too. The bufuralol 1’‐hydroxylase showed the highest hepatic activities compared with other CYP enzymes at all ages of pigs. The average activities at the age of 20 weeks were about five times higher than those at the age of 5 weeks for most of the CYP enzymes. With compensation of the ratio of liver to body weights, the overall CYP450 metabolism capability of the pigs may be peaked around ages of 10 to 20 weeks. Those findings suggest that metabolism can be significantly different in growing phase of pigs and that the age may be an important factor in porcine medicine evaluation and pig model development.     

Oxidative monensin metabolism and cytochrome P450 3A content and functions in liver microsomes from horses, pigs, broiler chicks, cattle and rats

The oxidative metabolism of monensin, an ionophore antibiotic extensively used in veterinary practice as a coccidiostat and a growth promoter, was studied in hepatic microsomal preparations from horses, pigs, broiler chicks, cattle and rats. As assayed by the measurement of the amount of the released formaldehyde, the rate of monensin O-demethylation was nearly of the same order of magnitude in all species, but total monensin metabolism, which was estimated by measuring the rate of substrate disappearance by a high-performance liquid chromatography (HPLC) method, was highest in cattle, intermediate in rats, chicks and pigs, and lowest in horses. When expressed as turnover number (nmol of metabolized monensin/min nmol cytochrome P450-1), the catalytic efficiency (chick > cattle > pig approximately rat > horse) was found to correlate inversely with the well known interspecies differences in the susceptibility to the toxic effects of the ionophore, which is characterized by an oral LD50 of 2-3 mg/kg bodyweight (bw) in horses, 50-80 mg/kg bw in cattle and 200 mg/kg bw in chicks. Chick and cattle microsomes also displayed both the highest catalytic efficiency toward two P450 3A dependent substrates (erythromycin and triacetyloleandomycin) and the highest immunodetectable levels of proteins cross-reacting with anti rat P450 3A1/2. Further studies are required to define the role played by this isoenzyme in the oxidative biotransformation of the drug in food producing species.     

Effect of Gossypol on Hepatic and Serum γ-glutamyltransferase Activity in Rats

A single intraperitoneal dose (25 mg/kg) of gossypol given to male Sprague-Dawley rats caused marked changes in the activity of the hepatic and serum -glutamyltransferase (GGT) and microsomal monooxygenases. The GGT activity in liver homogenate, S-9 supernatant fraction and microsomes was significantly depressed; however, the level of serum GGT was elevated. While the hepatic glutathione concentration was not greatly changed, the aminopyrine N-demethylase activity and microsomal cytochrome P450 content of the liver were significantly decreased in the treated rats. At necropsy, the livers of the treated rats appeared generally pale with distinct pinpoint foci. Histopathological examination of the liver showed degenerative changes and coagulative necrosis. The results indicate that gossypol is a strong hepatotoxic agent which can produce severe hepatic damage.     

Effects of multiple concurrent stressors on rectal temperature, blood acid-base status, and longissimus muscle glycolytic potential in market-weight pigs

Sixty-four market-weight (130.0 +/- 0.65 kg) barrows (n = 16) and gilts (n = 48) were used in a split-plot design with a 2 x 2 x 2 factorial arrangement of treatments: 1) handling intensity (gentle vs. aggressive), 2) transport floor space (0.39 vs. 0.49 m(2)/pig), and 3) distance moved during handling (25 vs. 125 m) to determine the effects of multiple concurrent stressors on metabolic responses. For the handling intensity treatment, pigs were moved individually approximately 50 m through a handling course with either 0 (gentle) or 8 (aggressive) shocks from an electric goad. Pigs were loaded onto a trailer and transported for approximately 1 h at floor spaces of either 0.39 or 0.49 m(2)/pig. After transport, pigs were unloaded, and the distance moved treatment was applied; pigs were moved 25 or 125 m through a handling course using livestock paddles. Rectal temperature was measured, and blood samples (to measure blood acid-base status) were collected 2 h before the handling intensity treatment was applied and immediately after the distance moved treatment was applied. A LM sample to measure glycolytic potential was collected after the distance moved treatments on a subset of 32 pigs. There were handling intensity x distance moved interactions (P < 0.05) for several blood acid-base measurements. In general, there was no effect of distance moved on these traits when pigs were previously handled gently. However, when pigs were previously handled aggressively, pigs moved 125 compared with 25 m had greater (P < 0.05) blood lactate and less (P < 0.05) blood pH, bicarbonate, and base-excess. Pigs transported at 0.39 compared with 0.49 m(2)/pig had a greater (P < 0.01) increase in creatine kinase values; however, transport floor space did not affect any other measurements. Data were analyzed by the number of stressors (the aggressive handling, restricted transport floor space, and 125-m distance moved treatments) experienced by each pig (0, 1, 2, or 3). As the number of stressors experienced by the pig increased, rectal temperature, blood lactate, and LM lactate increased linearly (P 相似文献   

Effect of excess levels of lysine and leucine in wheat‐based,amino acid‐fortified diets on the mRNA expression of two selected cationic amino acid transporters in pigs

An experiment was conducted to evaluate the effect of excess levels of Leu and Lys on the expression of b^0,+ and CAT‐1 mRNA in jejunum, liver and the muscles Longissimus dorsi (LDM) and Semitendinosus (STM). Twenty pigs with an average initial BW of 16.4 ± 1.7 kg were used in a Randomized Complete Block. Dietary treatments (T) were as follows: T1, basal diet; T2, basal plus 3.5 g l ‐Lys/kg diet; T3, basal plus 1.5 g l ‐Leu/kg diet; T4, basal plus 3.5 g l ‐Lys plus 1.5 g l ‐Leu/kg diet. Diets in T1 and T3 met 100% the requirement of Lys for pigs within the 10 to 20 kg body weight range; diets in T2 and T4 contained 35% excess of Lys. Also, diets in T1 and T2 supplied 104%, whereas diets in T3 and T4 supplied 116% the requirement of Leu. The expression of b^0,+ in jejunum was reduced (p = 0.002) because of the supplementation of l ‐Leu, but l ‐Lys supplementation had no effect (p = 0.738). In contrast, the expression of b^0,+ in STM (p = 0.012) and liver (p = 0.095) was reduced by the high level of Lys, but Leu had no effect (p > 0.100). CAT‐1 expression in STM increased by high Lys (p = 0.023) and Leu (p = 0.007) levels. In liver, the expression of CAT‐1 substantially increased (p = 0.001) because of Lys. In conclusion, excess levels of dietary Lys and Leu affect the expression of cationic amino acid transporters, and this effect varies depending on the studied tissue.     

In vitro and In vivo Association of Porcine Hepatic Cytochrome P450 3A and 2C Activities with Testicular Steroids

The aim of this study was to screen the inhibitory potential of several testicular steroids on cytochrome P450 3A (CYP3A) and 2C (CYP2C) activities in porcine liver microsomes. The microsomes used in this study were obtained from pubertal male pigs of two breeds, Landrace and Duroc. For the in vitro inhibition study, porcine microsomes were incubated in the presence of 17β‐estradiol, 17α‐estradiol, androstenone, dehydroepiandrosterone and dihydrotestosterone. Both reversible and mechanism‐based inhibitions were examined. 7‐benzyloxyresorufin (BR) and 7‐benzyloxy‐4‐trifluoromethylcoumarin (BFC) were used as substrates for CYP3A, and diclofenac and tolbutamide (TB) as substrates for CYP2C. 7‐benzyloxyresorufin O‐dealkylase (BROD) activity was inhibited by all tested steroids in the microsomes from Landrace pigs via mechanism‐based mode, but in the microsomes from Duroc pigs, BROD activities were inhibited only in the presence of 17β‐oestradiol. Mechanism‐based inhibition of BFC metabolism by the tested steroids was observed in the microsomes from both breeds, but this inhibition was weak and did not exceed 20%. TB hydroxylase (TBOH) activity in the microsomes from Duroc pigs was inhibited by 17α‐oestradiol through the mechanism‐based mode of inhibition. None of the investigated steroids inhibited TBOH activity in Landrace pigs. For the in vivo study, male pigs were injected with a single dose of human chorionic gonadotropin (hCG) to stimulate testicular steroid production by the Leydig cells. In vivo stimulation with hGC did not alter BROD activity either in Landrace or in Duroc pigs. BFC metabolism was significantly induced by hCG stimulation in both breeds and TBOH activity only in Duroc pigs. Activity of diclofenac hydroxylase was not detected in either Landrace or Duroc pigs. Breed significantly affected BROD and TBOH activity with BROD being higher in Landrace and TBOH in Duroc pigs. This study improved our understanding of the role of testicular steroids in the regulation of porcine CYP450 activity.     

Toxicology of aflatoxin B1, warfarin, and cadmium in young pigs: performance and hematology

Observations on the interactions of cadmium (Cd) x aflatoxin B1 (AFB1) and Cd x warfarin included several variables of animal performance and hematology. Cadmium was fed daily for 40 days (groups IV, V, VI) and a Cd-free diet was fed to groups I, II, and III. Groups II and V were treated with AFB1, and groups III and VI were treated with warfarin--each for 5 days during the 5th week of the experiment and the effects were observed for 10 days. All pigs fed the diet with added Cd had developed severe anemia by the 4th week of the experiment. The incorporation of this toxic concentration of Cd (83 micrograms/g) in the diet seemed to have blocked the liver microsomal enzyme system (cytochrome P-450), diminishing the toxic effects of 5 daily oral doses (0.2 mg/kg of body wt) of AFB1 (group V pigs), but enhancing synergistically the toxic anticoagulant effects of the same doses of warfarin in young pigs (group VI). The data presented also indicated that the feeding of toxic concentrations of Cd stimulated increased glutathione peroxidase activity, which conjugated the AFB1 epoxides with their excretion as reduced glutathione but enhanced the toxic anticoagulant effects of warfarin in young pigs.     

Tiamulin selectively inhibits oxidative hepatic steroid and drug metabolism in vitro in the pig

The simultaneous use of the antibiotic tiamulin with certain ionophoric antibiotics (monensin, salinomycin) may give rise to a toxic interaction in pigs and poultry. In the present study, effects of tiamulin on hepatic cytochrome P450 activities in vitro were studied using pig liver microsomes. When tiamulin was added to the incubation medium the N-demethylation rate of ethylmorphine and the hydroxylation of testosterone at the 6β- and 1 lα- positions was sirongly inhibited. Tiamulin inhibited these activities more than SKF525A or cimetidine, but less than ketoconazole. The microsomal N-demethylation rate of erythromycin and the hydroxylation of testosterone at the 28- position were inhibited to a lesser degree, whereas the ethoxyresorufin-O-deethylation, aniline hydroxylation and testosterone hydroxylations at the 15α- and 15β- positions were not affected by tiamulin. No in vitro complexation by tiamulin of cytochrome P450 resulting in a loss of CO-binding capacity could be demonstrated. Results from the present study suggest a selective inhibition of cytochrome P450 enzymes in pigs, probably belonging to the P4503A subfamily. The mechanism of this interaction is still unclear. However, interactions between tiamulin and those veterinary drugs or endogenous compounds which undergo oxidative metabolism by P450 enzymes must be considered. More research is needed to reveal which of the P450 enzymes are affected by tiamulin in order to improve the understanding and probably the predictability of this interaction.     

Dietary supplementation with carnosine improves antioxidant capacity and meat quality of finishing pigs

This study was conducted to determine the effect of dietary carnosine (β‐alanyl‐l ‐histidine) supplementation on antioxidant capacity and meat quality of pigs. 72 pigs approximately 60 kg were fed a corn‐ and soybean meal‐based diet supplemented with 0, 25, 50 or 100 mg carnosine per kg diet for 8 weeks. Carnosine supplementation did not affect growth performance and carcass traits of pigs. However, the addition of 100 mg carnosine per kg diet increased pH value of muscle at 45 min, 24 h and 48 h postmortem. It also decreased drip loss at 48 h postmortem and increased redness value of muscle at 45 min postmortem (p < 0.05). The addition of 100 mg carnosine per kg diet enhanced glycogen concentration and Ca‐ATPase activity at 24 and 48 h postmortem, and reduced malondialdehyde and carbonyl protein complexes concentrations in muscle at 24 h postmortem (p < 0.05). The addition of 100 mg carnosine per kg diet increased glutathione peroxidase (GSH‐Px), superoxide dismutase (SOD) and catalase (CAT) activities in plasma, liver or muscle, as well as SOD and GSH‐Px genes expression in muscle (p < 0.05). Taken together, these findings indicate that carnosine supplementation improves antioxidant capacity and meat quality of pigs.     

Pituitary porcine growth hormone (pGH) and a recombinant pGH analog stimulate pig growth performance in a similar manner

This study was conducted to establish the extent to which different doses of pituitary porcine growth hormone (ppGH) increase pig growth performance. Pigs were treated daily for 11 wk with 0, 35 or 70 micrograms ppGH/kg BW. In addition, these effects were compared with those produced by treating pigs with 0, 35, 70 or 140 micrograms.kg BW-1.d-1 of a recombinantly derived analog of porcine growth hormone (rpGH). This analog lacks the first seven amino acids at the NH2 terminus. Growth rate was increased similarly by ppGH and rpGH (the maximal increase was 19%). Feed efficiency was improved by ppGH and rpGH (the maximal response was 25%). This improvement in feed efficiency was associated with a decrease in feed intake (17% with the largest dose of rpGH). Both ppGH and rpGH decreased adipose tissue growth and increased muscle mass. Carcass lipid was decreased by 68% in pigs treated with the largest dose of rpGH. The recombinant pGH analog appeared to be less potent than ppGH in decreasing adipose tissue growth rate. All other parameters measured, however, indicated that rpGH mimicked the biological effects of ppGH (including binding to pig liver membranes and induction of insulin-like growth factor I production). Sensory panel evaluations indicated that neither ppGH nor rpGH affected pork palatability. Larger doses of pGH (greater than 70 micrograms/kg BW) adversely affected pig mobility. This impairment in mobility appears to be due to osteochondrosis. Our findings establish that the rpGH analog is equipotent to ppGH in stimulating growth performance and that pigs can be treated without any significant adverse effects when they are treated with less than 70 micrograms of pGH.kg BW-1.d-1.     

Safety of orally administered,USP‐compliant levothyroxine sodium tablets in dogs

The safety of synthetic levothyroxine sodium tablets (Thyro‐Tabs® Canine; LLOYD , Inc.) in dogs was evaluated in a randomized, sham‐dose controlled, parallel‐group study. Young, healthy, euthyroid Beagle dogs were randomized into four groups (four females and four males per group) and received single daily doses of 0×, 2× (0.044 mg/kg), 6× (0.132 mg/kg), or 10× (0.22 mg/kg) the labeled starting dose of 0.022 mg kg^?1 day^?1 for 182 days. Every 2 weeks, physical examinations, electrocardiology examinations, and sample collections for thyroid panel, hematology, serum biochemistry, coagulation panel, and urinalysis were performed. At the end of the study, the dogs were euthanized and full necropsies performed. The most overt finding was the expected dose‐dependent increase in serum concentrations of total and free thyroxine with dose‐dependent suppression of the hypothalamic–pituitary–thyroid axis as evidenced by decreased serum thyroid‐stimulating hormone concentrations, decreased thyroid+parathyroid/body weight ratios, and a trend for decreased pituitary weight/brain weight ratios. Clinical signs of thyrotoxicosis (excitation, tachypnea, tachycardia) in the treated dogs were sporadic with no dose–response relationship. Other findings statistically associated with levothyroxine treatment were generally mild and not clinically important. In summary, doses of levothyroxine sodium up to 10× the labeled starting dose were well tolerated in healthy dogs.     

Species differences in hepatic biotransformation of the anthelmintic drug flubendazole

Flubendazole (FLBZ) is a broad‐spectrum benzimidazole anthelmintic used in pigs, poultry, and humans. It has been proposed as a candidate for development for use in elimination programmes for lymphatic filariasis and onchocerciasis in humans. Moreover, FLBZ has shown promise in cancer chemotherapy, particularly for neuroblastoma. This work investigated the hepatic carbonyl‐reducing pathway of FLBZ in different species, including humans. Microsomal and cytosolic fractions were obtained from sheep, cattle, pig, hen, rat, and human liver. Both subcellular fractions of each species converted FLBZ into a reduced metabolite (red‐FLBZ). The rate of microsomal red‐FLBZ production was highest in sheep (1.92 ± 0.13 nmol/min.mg) and lowest in pigs (0.04 ± 0.02 nmol/min.mg); cytosolic red‐FLBZ production ranged from 0.02 ± 0.01 (pig) to 1.86 ± 0.61 nmol/min.mg (sheep). Only subcellular fractions from sheep liver oxidized red‐FLBZ to FLBZ in a NADP⁺‐dependent oxidative reaction. Liver microsomes from both pigs and humans transformed FLBZ to red‐FLBZ and a hydrolyzed metabolite. Very significant differences in the pattern of FLBZ metabolism were observed among the tested species and humans. These results reinforce the need for caution in extrapolating data on metabolism, efficacy, and safety of drugs derived from studies performed in different species.     

Influences of lipopolysaccharide-induced immune challenge on performance and whole-body protein turnover in weanling pigs

The objective of this study is to characterize the influence of immune stress induced by lipopolysaccharide (LPS) on protein utilization and turnover for early-weaned pigs. A total of 15, crossbred weanling pigs (initial body weight 10.15 ± 0.39 kg) were assigned to one of three treatments. Pigs were injected with LPS and fed ad libitum (LPS-challenge), or injected with endotoxin-free physiological salt solution (PSS) and fed ad libitum (control), or injected with PSS and fed the same amount of feed as LPS-challenged pigs (pair-feed). All pigs received a 4-d nitrogen balance trial. On d 1 and 3 of the trial, LPS-challenged pigs were injected intramuscularly with 200 μg/kg BW of LPS dissolved in 1 ml PSS. Pigs in other treatments were injected with 1 ml PSS. ¹⁵N-Glycine (5 mg/kg BW) was gastrically infused after the second injection. Feces and urine were collected daily to determine the N output throughout the duration of the trial. Lymphocyte blastogenesis (LB) and serum immunoglobulins (IgA, IgG, IgM) were also detected to illustrate the LPS-induced immune responses. Results indicated that the injection of LPS significantly (P < 0.01) elevated the LB and resulted in lower average daily gain (ADG), feed intake (ADFI) and efficiency of feed utilization than control pigs. Pair-fed pigs had higher performance than LPS-challenged pig but poorer than control pigs. Injection of LPS also resulted in significantly (P < 0.01) lower nitrogen intake and efficiency of utilization than controls, and more fecal N excretion than Pair-fed pigs (3.19 ± 0.85 vs. 2.19 ± 0.67 g/d, P < 0.05). The whole-body nitrogen flux (4.34 ± 0.19 vs. 11.35 ± 0.12 g N/kg BW^0.75/d) and N accretion (5.57 ± 0.59 vs. 10.17 ± 1.12 g Pr/kg BW^0.75/d) were acutely (P < 0.01) reduced as the feed intake decreased, but there was no significant difference between LPS-challenged and pair-fed pigs. Injection of LPS markedly (P < 0.05) increased the protein degradation (16.76 ± 1.09 vs. 14.53 ± 1.24 g N/kg BW^0.75/d). It is concluded that LPS-induced immune challenge depresses growth performance and feed utilization efficiency by enhancing protein degradation rate and decreasing protein utilization for body protein retention.     

Effect of added dietary threonine on growth performance,health, immunity and gastrointestinal function of weaning pigs with differing genetic susceptibility to Escherichia coli infection and challenged with E. coli K88ac

Threonine (Thr) is important for mucin and immunoglobulin production. We studied the effect of added dietary Thr on growth performance, health, immunity and gastrointestinal function of weaning pigs with differing genetic susceptibility to E. coli K88ac (ETEC) infection and challenged with ETEC. Forty‐eight 24‐day‐old weaned pigs were divided into two groups by their ETEC susceptibility using mucin 4 (MUC4) gene as a marker (2 MUC4^?/?, not‐susceptible, and 2 MUC4^+/+, susceptible, pigs per litter). Within genotype, pigs were fed two different diets: 8.5 (LThr) or 9.0 (HThr) g Thr/kg. Pigs were orally challenged on day 7 after weaning and slaughtered on day 12 or 13 after weaning. Before ETEC challenge, HThr pigs ate more (p < 0.05). The diet did not affect post‐challenge growth, but HThr tended to increase post‐challenge feed efficiency (p = 0.087) and overall growth (p = 0.087) and feed efficiency (p = 0.055). Before challenge, HThr pigs excreted less E. coli (p < 0.05), while after challenge, diet did not affect the number of days with diarrhoea and ETEC excretion. MUC4^+/+ pigs responded to the challenge with more diarrhoea, ETEC excretion and anti‐K88 IgA in blood and jejunal secretion (p < 0.001). HThr pigs had a higher increase of anti‐K88 IgA values in jejunal secretion (p = 0.089) and in blood (p = 0.089, in MUC4^+/+ pigs only). Thr did not affect total IgA and IgM values, morphometry of jejunum, goblet cells count in colon, total mucin from jejunum and colon, but varied jejunal goblet cells counts (p < 0.05). In the first two post‐weaning weeks, 8.5 g Thr/kg diet may be not sufficient to optimize initial feed intake, overall feed efficiency and intestinal IgA secretion and to control the gut microbiota in the first post‐weaning week, irrespective of the pig genetic susceptibility to ETEC infection.     

饲粮铁、铜水平对早期断奶仔猪生长发育及组织铁、铜含量的影响

本试验就饲粮铁、铜水平对早期断奶仔猪(30日龄)生长发育及组织中铁、铜含量的影响进行了研究。结果指出:在含铁70mg/kg及含铜10mg/kg的基础饲料中以硫酸亚铁形式添加35及70mg/kg铁和以硫酸铜形式添加125及200mg/kg铜时,对仔猪生长性能、组织器官的发育以及品骨、肾脏中的铁含量没有影响,但饲粮铁水平的增加可导致肝脏和脾脏铁含量的增加。在饲粮中添加35mg/kg及70mg/kg的铁时,可使肝脏铁含量增加14.6％和55.0％(P<0.01),使脾脏铁含量增加15.1％(P<0.05)及22.9％(P<0.01)。在仔猪饲粮中添加200mg/kg铜,可使仔猪日增重和采食量分别提高9.7％和16.2％,使肾脏和肝脏铜含量分别增加104.6％(P<0.01)和434.0％(P<0.01),使肝脏铁含量降低19.4％(P<0.05)。添加125mg/kg铜,使肾脏和肝脏铜增加27.9％和93.4％(P<0.01),使肝脏铁降低9.4％。     

Albendazole treatment in laying hens: Egg residues and its effects on fertility and hatchability

This work characterized the egg residual concentrations of albendazole (ABZ ) and its sulphoxide (ABZSO ) and sulphone (ABZSO ₂) metabolites and evaluated their effect on egg fertility and hatchability after ABZ treatments to laying hens. Seventy hens were allocated in groups: Group‐1 was the control without treatment; Group‐2 received a single ABZ oral dose (10 mg/kg); Group‐3, ‐4 and ‐5 were treated with ABZ in medicated feed over 7 days at 10, 40, or 80 mg kg^?1 day^?1, respectively. Eggs were analyzed to determine the ABZ /metabolite level by HPLC or subjected to incubation to evaluate the fertility and hatchability. Only ABZSO and ABZSO ₂ metabolites were quantified in egg after ABZ single oral administration with maximum concentrations of 0.47 ± 0.08 and 0.30 ± 0.07 μg/ml, respectively. ABZ and its metabolites were found in eggs after 7‐day ABZ treatments. The egg residue exposure estimated as AUC s (areas under the concentration vs . time curve) were 100.5 (ABZ ), 56.3 (ABZSO ) and 141.3 μg hr g^?1 (ABZSO ₂). ABZ administration did not affect the egg fertility at any dosages. Egg hatchability was not affected by ABZ treatment at 10 mg/kg in medicated feed, but it decreased when the dose was 4–8 times higher. These results should be considered when ABZ is used for deworming laying hens.