High Lever Dietary Copper Promote Ghrelin Gene Expression in the Fundic Gland of Growing Pigs

This experiment was conducted to examine the effect of dietary copper supplementation on ghrelin mRNA expression level in the fundic gland of growing pigs. A total of 45 crossbred pigs were randomly assigned to three groups of 15 pigs, five replicates of three animals comprised each group. Pigs were allocated to diets that contained 5?mg/kg copper (as the control group), 125?mg/kg copper sulfate, or 125?mg/kg copper methionine. At the end of the experiment, five pigs were selected at random from each group, slaughtered, and collected the fundic gland for determination of ghrelin mRNA expression level. The results showed that average daily gain, average daily feed intake, absolute weight, serum growth hormone (GH) concentration, and ghrelin mRNA level were higher in pigs fed the diets with 125?mg/kg copper methionine and 125?mg/kg copper sulfate (P?<?0.05), than in pigs fed a diet with 5?mg/kg copper. These data suggest that high dietary copper (125?mg/kg) appears to increase feed intake and promote weight gain by enhancing the secretion of GH and ghrelin mRNA level in growing pigs.     

Effect of high dietary copper on weight gain and neuropeptide Y level in the hypothalamus of pigs

An experiment was performed to examine the effect of dietary copper supplementation on weight gain, neuropeptide Y (NPY) concentration and NPY mRNA expression level in the hypothalamus of pigs. Forty-five crossbred pigs were randomly assigned to three groups of 15 pigs, each comprising five replicates of 3 animals. Pigs were allocated to diets that contained 10 mg/kg (as a control), 125 and 250 mg/kg copper as CuSO₄. Live weight gain and feed conversion efficiency was determined at the end of the experiment and five pigs, selected at random from each group, were slaughtered and the hypothalami collected for determination of NPY concentration and NPY mRNA expression level. The results showed that average daily gain (ADG) and average daily feed intake (ADFI) were higher and feed:gain (F:G) ratio was lower in pigs fed the diets with 125 and 250 mg/kg copper (P<0.05), respectively, than in pigs fed a diet with 10 mg/kg copper, but that there was no statistically significant difference in growth performance between animals of the 125 mg/kg and the 250 mg/kg copper groups. Furthermore, pigs fed diets with 125 and 250 mg/kg copper had higher NPY concentrations and NPY mRNA expression levels in their hypothalamus than control animals. The data indicated that 125 and 250 mg/kg copper gave similar responses in terms of weight gain, whilst high dietary copper could enhance NPY concentration and NPY mRNA expression level in the hypothalamus of pigs. High dietary copper appears to increase feed intake and promote weight gain by enhancing NPY concentration and NPY mRNA expression level in the hypothalamus of pigs.     

Dietary Glutamate Supplementation Ameliorates Mycotoxin-Induced Abnormalities in the Intestinal Structure and Expression of Amino Acid Transporters in Young Pigs

The purpose of this study was to investigate the hypothesis that dietary supplementation with glutamic acid has beneficial effects on growth performance, antioxidant system, intestinal morphology, serum amino acid profile and the gene expression of intestinal amino acid transporters in growing swine fed mold-contaminated feed. Fifteen pigs (Landrace×Large White) with a mean body weight (BW) of 55 kg were randomly divided into control group (basal feed), mycotoxin group (contaminated feed) and glutamate group (2% glutamate+contaminated feed). Compared with control group, mold-contaminated feed decreased average daily gain (ADG) and increased feed conversion rate (FCR). Meanwhile, fed mold-contaminated feed impaired anti-oxidative system and intestinal morphology, as well as modified the serum amino acid profile in growing pigs. However, supplementation with glutamate exhibited potential positive effects on growth performance of pigs fed mold-contaminated feed, ameliorated the imbalance antioxidant system and abnormalities of intestinal structure caused by mycotoxins. In addition, dietary glutamate supplementation to some extent restored changed serum amino acid profile caused by mold-contaminated feed. In conclusion, glutamic acid may be act as a nutritional regulating factor to ameliorate the adverse effects induced by mycotoxins.     

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.     

Meat meal in the diet of the early-weaned pig IV. The supplementation of diets with tryptophane,lysine and methionine

Two experiments were conducted with 72 pigs between 28 and 56 days of age to study the effect of tryptophane supplementation on their performance when fed on diets containing wheat and meat meal.In the first experiment, pigs were fed on a basal diet (Diet 1) or on the same diet supplemented with calcium dihydrogen phosphate (Diet 2), bone meal (Diet 3) or bone meal plus tryptophane (Diet 4), all to 3.1% calcium. The weight gains of the pigs (315 g day^?1) fed on Diet 3 were significantly lower than that of the pigs fed on the other three diets (363 g day^?1). The feed conversion ratios showed a similar trend. Diet 3 contained 0.16% tryptophane while the other diets contained 0.18–0.19% tryptophane. The crude protein, lysine and methionine contents of all diets were similar.In the second experiment, a basal diet containing meat meal and bone meal was supplemented with tryptophane, lysine plus methionine or all three amino acids. Feed intake was increased by all amino acid supplements. Weight gains were improved significantly (57%) by the addition of all three amino acids to the diets, but the improvements due to tryptophane alone (28%) or methionine plus lysine (35%) were not significant. Tryptophane supplementation alone or with lysine plus methionine increased the nitrogen retention of the pigs.It was concluded that the requirement for tryptophane of pigs between 28 and 56 days of age was greater than 0.16% of diets containing wheat and meat meal.     

Modelling the variation in performance of a population of growing pig as affected by lysine supply and feeding strategy

Considerable progress has been made in the nutritional modelling of growth. Most models typically predict (or analyse) the response of a single animal. However, the response to nutrients of a single, representative animal is likely to be different from the response of the herd. To address the variation in response between animals, a stochastic approach towards nutritional modelling is required. In the present study, an analysis method is presented to describe growth and feed intake curves of individual pigs within a population of 192 pigs. This method was developed to allow end-users of InraPorc (a nutritional model predicting and analysing growth in pigs) to easily characterise their animals based on observed data and then use the model to test different scenarios. First, growth and intake data were curve-fitted to characterise individual pigs in terms of BW (Gompertz function of age) and feed intake (power function of BW) by a set of five parameters, having a biological or technico-economical meaning. This information was then used to create a population of virtual pigs in InraPorc, having the same feed intake and growth characteristics as those observed in the population. After determination of the mean lysine (Lys) requirement curve of the population, simulations were carried out for each virtual pig using different feeding strategies (i.e. 1, 2, 3 or 10 diets) and Lys supply (ranging from 70% to 130% of the mean requirement of the population). Because of the phenotypic variation between pigs and the common feeding strategies that were applied to the population, the Lys requirement of each individual pig was not always met. The percentage of pigs for which the Lys requirement was met increased concomitantly with increasing Lys supply, but decreased with increasing number of diets used. Simulated daily gain increased and feed conversion ratio decreased with increasing Lys supply (P < 0.001) according to a curvilinear-plateau relationship. Simulated performance was close to maximum when the Lys supply was 110% of the mean population requirement and did not depend on the number of diets used. At this level of Lys supply, the coefficient of variation of simulated daily gain was minimal and close to 10%, which appears to be a phenotypic characteristic of this population. At lower Lys supplies, simulated performance decreased and variability of daily gain increased with an increasing number of diets (P < 0.001). Knowledge of nutrient requirements becomes more critical when a greater number of diets are used. This study shows the limitations of using a deterministic model to estimate the nutrient requirements of a population of pigs. A stochastic approach can be used provided that relationships between the most relevant model parameters are known.     

Meat meal in the diet of the early-weaned pig. II. Amino acid supplementation

One hundred and twenty pigs, initially 4–5 kg liveweight, were fed on wheat-based diets supplemented with meat meal and amino acids in two experiments, each of 4 weeks duration.In the first experiment, the supplementation of a normal meat meal diet with lysine and methionine increased the feed intake and weight gains of the pigs by 15 and 18%, respectively. Nitrogen retention was increased by 30%. Tryptophane gave a similar response to lysine and methionine.In the second experiment, a 21% crude protein basal diet was similar to the basal diet of the first experiment but it contained 1.02% lysine and 0.50% methionine plus cystine, compared to 0.90 and 0.51%, respectively, in the first experiment. Lysine and methionine supplementation of the diet did not significantly improve the performance of the pigs in the second experiment, but the supplementation of the diets with 0.08% tryptophane and lysine and methionine increased weight gains and feed intakes and decreased urea content of the blood plasma. The 21% crude protein diet contained 0.15% tryptophane.Increasing the crude protein content of diets from 18 to 24% by increasing their meat meal content increased the daily weight gains from 190 to 276 g.     

Efficacy of virginiamycin and a commercially-available lactobacillus probiotic in swine diets

Eight feeding trials using 708 cross-bred pigs were conducted to evaluate the addition of virginiamycin and a commercially-available lactobacillus fermention product (probiotic) to starter, grower and finisher diets based on maize and soya bean meal. Virginiamycin was added at a level of 11 mg/kg of diet, and lactobacillus probiotic at 1 g/kg in starter diets and 500 mg/kg in grower and finisher diets. In the combined analysis of four starter trials, pigs fed on diets containing virginiamycin tended to eat more and grow faster than pigs fed on the control diet, but feed efficiency was not different. Furthermore, daily gain, daily feed intake and feed efficiency were not improved by the addition of lactobacillus probiotic to starter diets. In the combined analysis of a starter—grower—finisher and a grower—finisher trial, virginiamycin supplementation did not alter overall pig performance compared with control. Pigs fed on a positive control diet containing chlortetracycline, penicillin and sulfamethazine had a nonsignificantly greater daily gain and feed intake.Daily gain for the lactobacillus probiotic-fed pigs was lower (P < 0.05) than that of the negative controls, but daily feed intake and feed efficiency were not significantly different. In three growing—finishing trials in which virginiamycin and lactobacillus probiotic were compared in a 2 × 2 factorial arrangement of treatments, daily gain and feed intakes were greater (P < 0.01) for pigs given virginiamycin. The lactobacillus probiotic did not improve daily gain, feed intake or feed efficiency. Overall, no interaction between virginiamycin and lactobacillus probiotic occurred.     

A comparison between meals prepared from the seeds of different varieties of lupin as protein supplements to barley-based diets for growing pigs

Four experiments were conducted in order to examine the growth and voluntary feed consumption of young growing pigs fed on barley-based diets containing as the sole protein supplement lupin-seed meal (LSM) from either Lupinus angustifolius cv. Uniwhite (UW), Uniharvest (UH) or L. albus cv. Neuland (NL).Under the restricted feeding regimen of the first experiment pigs receiving diets containing either 31% or 43% of either UW or UH grew at similar rates and with similar efficiency of feed utilisation from 27.5 to 85 kg live weight. By contrast, all pigs fed on diets containing these same proportions of NL refused such large amounts of feed immediately after the diets were offered that their growth halted.In the second and third experiments the voluntary feed consumption of pigs weighing 18 to 34 kg and receiving diets containing 37 to 43% of any of three distinct lines of NL was significantly less than those of pigs receiving UW diets, to the extent in some cases that body-weight loss occurred.In the fourth experiment the growth and voluntary feed intakes of 20 to 30 kg pigs fed on a control diet containing a mixture of fishmeal and dried blood as the protein supplement were greater than those of pigs fed a UW diet, which in turn were greater than those of pigs receiving NL as the source of supplementary protein. Reduction of the alkaloid content of NL by ethanol extraction resulted in a recovery of growth and feed intake to levels similar to those supported by the UW diet.     

The potential effects of antioxidant feed additives in mitigating the adverse effects of corn naturally contaminated with <Emphasis Type="Italic">Fusarium</Emphasis> mycotoxins on antioxidant systems in the intestinal mucosa,plasma, and liver in weaned pigs

Seventy-two piglets (6.0 kg BW) were randomly distributed within six different dietary treatments to evaluate the effect of deoxynivalenol (DON) and the potential of four antioxidant feed additives in mitigating the adverse effects of DON on growth performances and oxidative status. Dietary treatments were as follows: control diet 0.8 mg/kg DON; contaminated diet (DON-contaminated diet) 3.1 mg/kg DON; and four contaminated diets, each supplemented with a different antioxidant feed additive, DON + vitamins, DON + organic selenium (Se)/glutathione (GSH), DON + quercetin, and DON + COMB (vitamins + Se/GSH + quercetin from the other treatments). Although DON was the main mycotoxin in the contaminated diet, this diet also contained 1.8 mg/kg of zearalenone (ZEN). The “mycotoxin” effects therefore included the combined effect of these two mycotoxins, DON, and ZEN. The DON-ZEN ingestion did not affect growth performances, average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (G:F ratio), but partially induced oxidative stress in weaned pigs as shown by increased malondialdehyde (MDA) content in the plasma and superoxide dismutase (SOD) activity in liver (P?<?0.05). However, no change in the activity of other antioxidant enzymes or GSH concentrations was observed in plasma and liver of piglets fed the DON-contaminated diet (P?>?0.05). Supplementation with individual antioxidant feed additive had a limited effect in weaned pigs fed DON-ZEN-contaminated diets. Combination of antioxidants (vitamins A, C, and E, quercetin, and organic Se/GSH) reduced plasma and liver MDA content and SOD activity in liver (P?<?0.05) of piglets fed DON-ZEN-contaminated diets. Furthermore, this combination also reduced MDA content in the ileum (P?<?0.05), although activity of glutathione peroxidases (GPx), SOD or catalase (CAT) in the ileum was not affected by DON-ZEN contamination or antioxidant supplements. In conclusion, DON-ZEN contamination induced oxidative stress in weaned pigs and combination of antioxidant feed additives restored partially the oxidative status. Further studies will be necessary to assess whether the effects of antioxidant feed additives on oxidative status are specific when feed is contaminated with DON-ZEN.     

Undecorticated cottonseed meal as a substitute for soya bean meal in diets for weaner and growing-finishing pigs

Fifty-six weaner and growing-finishing Large White × Landrace pigs were used in two growth studies and a digestibility study to determine the value of undecorticated cottonseed meal (UCSM) as a protein supplement replacing soya bean meal (SBM). In a 35-day feeding experiment with pigs averaging 18.8 kg, four lots of six pigs were individually fed on isonitrogenous diets containing 0, 10, 20 and 30% UCSM. Daily feed intake (FI) did not differ significantly between treatments. Daily gain and feed/gain did not differ significantly between the control and the 10% UCSM diets but the control group gained significantly more than the 20 or 30% UCSM diets (P < 0.05).

In a second growth experiment lasting 35 days, 24 cross-bred pigs averaging 53.1 kg were fed on diets containing 0, 20, 30 and 41.1% UCSM (without SBM) in a randomized design involving six individually fed pigs per treatment. There were no differences in FI across the treatments. Weight gain was significantly depressed with only 20% UCSM and both gain and feed/gain declined linearly with increasing proportion of UCSM. The growth studies showed that 10% was the optimum level of inclusion of UCSM in the diets. These were supported by the results of the metabolic studies.     

Changes in enzymatic activity of small intestine and kidney of rats by a methionine deficient diet

The effect of methionine dietary deficiency on food intake, weight gain, liver and kidney weight, feed conversion rate, protein efficiency ratio, maltase and leucineaminopeptidase (LAPase) activities of the intestinal mucosa as well as renal LAPase activity was studied. Three groups of female Wistar rats, weighing between 40-60 g, were fed for 25 days on either Diet A (casein supplemented with 0.6% DL-methionine), Diet B (amino acid mixture simulating casein also supplemented with 0.6% methionine) or Diet C (amino acid mixture with 0.67% methionine deficiency with respect to Diet A). The results show no significant differences in either growth or enzymatic activity between the rats fed on Diet A and those on Diet B. The animals fed on Diet C show an increase in intestinal (P less than 0.01, vs Diet B) and renal (P less than 0.005, vs Diet A) LAPase activity, although intestinal maltase activity remained unchanged. Food intake, weight gain, organ weight and nutritional parameters obtained in rats fed on Diet C showed no statistically significant changes, with the exception of kidney weight which decreased (P less than 0.005) when compared to those fed on Diet B.     

Effects of ad libitum and restricted feeding on early production performance and body composition of Yorkshire pigs selected for reduced residual feed intake

Residual feed intake (RFI), defined as the difference between observed and expected feed intake based on growth and backfat, has been used to investigate genetic variation in feed efficiency in cattle, poultry and pigs. However, little is known about the biological basis of differences in RFI in pigs. To this end, the objective of this study was to evaluate the fifth generation of a line of pigs selected for reduced RFI against a randomly selected Control line for performance, carcass and chemical carcass composition and overall efficiency. Here, emphasis was on the early grower phase. A total of 100 barrows, 50 from each line, were paired by age and weight (22.6 ± 3.9 kg) and randomly assigned to one of four feeding treatments in 11 replicates: ad libitum (Ad), 75% of Ad (Ad75), 55% of Ad (Ad55) and weight stasis (WS), which involved weekly adjustments in intake to keep body weight (BW) constant for each pig. Pigs were individually penned (group housing was used for selection) and were on treatment for 6 weeks. Initial BW did not significantly differ between the lines (P > 0.17). Under Ad feeding, the low RFI pigs consumed 8% less feed compared with Control line pigs (P < 0.06), had less carcass fat (P < 0.05), but with no significant difference in growth rate (P > 0.85). Under restricted feeding, low RFI pigs under the Ad75 treatment had a greater rate of gain while consuming the same amount of feed as Control pigs. Despite the greater gain, no significant line differences in carcass composition or carcass traits were observed. For the WS treatment, low RFI pigs had similar BW (P > 0.37) with no significant difference in feed consumption (P > 0.32). Overall, selection for reduced RFI has decreased feed intake, with limited differences in growth rate but reduced carcass fat, as seen under Ad feeding. Collectively, results indicate that the effects of selection for low RFI are evident during the early grower stage, which allows for greater savings to the producer.     

蛋氨酸羟基类似物对肉鸡骨骼性能和基因表达的影响

本文以雄性罗斯肉鸡为材料,探讨饲粮添加不同蛋氨酸源:蛋氨酸(DLM)、蛋氨酸羟基类似物(HMTBA)和蛋氨酸羟基类似物钙盐(HMTB-Ca)对肉鸡骨骼性能和基因表达的影响。结果表明,HMTBA和HMTB-Ca能提高肉鸡终体重、日增重、血液GSH/GSSG比值、抗氧化酶(CAT)水平、总抗氧化能力(T-AOC)、骨骼长度、重量、骨骼指数(p<0.05)。不同蛋氨酸源对肉仔鸡采食量、料重比和灰分含量影响不显著(p>0.05),HMTBA组骨生长分化因子-5(GDF-5)表达量显著上升(p<0.05)。HMTB-Ca显著提高骨骼强度、钙磷含量,下调金属基质蛋白酶-2(MMP-2)、金属基质蛋白酶-9(MMP-9)的表达水平(p<0.05)。由此可知,采食蛋氨酸羟基类似物及其钙盐饲粮,可提高肉鸡体增重,改善血液氧化还原状态,改善骨骼生长发育,其中HMTB-Ca对骨骼作用更显著。     

Mycotoxin-contaminated diets and an adsorbent affect the performance of Nellore bulls finished in feedlots

Mycotoxins are present in almost all feedstuffs used in animal nutrition but are often ignored in beef cattle systems, even though they can affect animal performance. The objective of this study was to evaluate the effects of mycotoxins and a mycotoxin adsorbent (ADS) on performance of Nellore cattle finished in a feedlot. One hundred Nellore cattle (430 ± 13 kg) were used in a randomized complete block design with a 2 × 2 factorial arrangement of treatments. The factors consisted of two diets with either natural contamination (NC) or exogenous contamination (EC) and the presence (1 g/kg of DM; ADS) or absence of a mycotoxin adsorbent. The NC and EC diets had the following contaminations, respectively: 0.00 and 10.0 µg/kg aflatoxins, 5114 and 5754 µg/kg fumonisins, 0.00 and 42.1 µg/kg trichothecenes B, 0.00 and 22.1 µg/kg trichothecenes A and 42.9 and 42.9 µg/kg fusaric acid. At the beginning of the experiment, all animals were weighed, and four randomly selected animals were slaughtered to evaluate the initial carcass weight. After 97 days of treatment, all animals were weighed and slaughtered. There was no interaction among factors for the DM intake (DMI; P = 0.92); however, there was a tendency for the EC diets to decrease the DMI by 650 g/day compared to animals fed NC diets (P = 0.09). There was a trend for interaction among factors (P = 0.08) for the average daily gain (ADG), where the greatest ADG was observed for cattle fed the NC diet (1.77 kg), and the lowest was observed for those fed the EC diet (1.51 kg). The NC + ADS and EC + ADS treatments presented intermediate values for ADG. The animals fed the NC diet had a greater final BW (596 kg) than animals fed the EC treatment (582 kg; P = 0.04). There was a tendency for interaction among factors for carcass gain (P = 0.08). Similarly to ADG, the highest carcass gain was observed for animals fed the NC diet (1.20 kg), and the lowest was observed for those fed the EC diet (1.05 kg). The NC + ADS and EC + ADS treatments presented intermediate values. The natural contamination groups had greater carcass gain than that of the EC groups, and the use of the ADS recovered part of the weight gain in animals fed the EC diet. In conclusion, mycotoxins at the levels evaluated affected the performance of beef cattle, and adsorbents may mitigate their impact.     

Effects of Pharmacological Concentrations of Dietary Zinc Oxide on Growth of Post-weaning Pigs: A Meta-analysis

Pharmacological dietary zinc (Zn) concentrations of 1,000 to 3,000 mg/kg diet from Zn oxide have been found to increase growth in post-weaning pigs. However, results were inconsistent among studies. A frequentist meta-analysis, in which effects were numerically described with standardized effect sizes (Hedges's g), was conducted in order to identify and quantify the responses in average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G/F) in post-weaning pigs upon dietary Zn supplementation from Zn oxide. The inability of independent continuous variables to explain significant heterogeneity obtained with fixed effect models necessitated the use of random effects models to calculate summary statistics. Dietary Zn supplementation increased (P?<?0.05) ADG (mean effect size?=?1.086, 95 % confidence intervals?=?0.905–1.266, 26 studies, 72 comparisons), ADFI (mean effect size?=?0.794, 95 % confidence intervals?=?0.616–0.971, 25 studies, 71 comparisons), and G/F (mean effect size?=?0.566, 95 % confidence intervals?=?0.422–0.710, 24 studies, 70 comparisons). Zinc oxide provided a feasible alternative to in-feed antibiotics to improve growth in post-weaning pigs, and its reduction in diets due to potential environmental pollution will have to be negated by alternative feed additives and management strategies in order to prevent economic losses.     

Effect of High Dietary Copper on Somatostatin and Growth Hormone-Releasing Hormone Levels in the Hypothalami of Growing Pigs

This experiment was conducted to examine the effect of dietary copper supplementation on somatostatin (SS) and growth hormone-releasing hormone (GHRH) mRNA expression levels in the hypothalami of growing pigs. A total of 45 crossbred pigs were randomly assigned to three groups of 15 pigs each; five replicates of three animals comprised each group. Pigs were allocated to diets that contained 5 mg/kg copper (control), 125 mg/kg copper sulfate, or 125 mg/kg copper methionine. At the end of the experiment, five pigs were selected at random from each group and slaughtered, and hypothalami were collected for determination of SS and GHRH mRNA expression levels. The results showed that the SS expression levels were lower and the GHRH levels were higher in pigs fed the diets with 125 mg/kg copper methionine (P < 0.05) and 125 mg/kg copper sulfate (P < 0.05), respectively, than in pigs fed the diet with 5 mg/kg copper. Furthermore, the relationship between SS mRNA and GHRH mRNA abundance had a significantly negative correlation (P < 0.05). The data indicated that high dietary copper could enhance GHRH mRNA expression levels and suppress SS mRNA expression levels in the hypothalami of pigs. High lever dietary copper (125 mg/kg copper sulfate or 125 mg/kg copper methionine) increased pigs’ growth performance and feed efficiency but had no significant effect on daily feed intake; 125 mg/kg copper sulfate or 125 mg/kg copper methionine at the same lever had no difference on growth promoting in pigs.     

Effects of dietary protein supply, weaning age and experimental enterotoxigenic Escherichia coli infection on newly weaned pigs: performance

An experiment was conducted to investigate the effects of post-weaning dietary protein supply and weaning age on the performance of pigs in the absence of in-feed antimicrobial growth promoters (AGP) when artificially challenged with enterotoxigenic Escherichia coli (ETEC), a pathogen associated with post-weaning colibacillosis (PWC). The experiment consisted of a complete 2 × 2 × 2 factorial combination of two weaning ages (4 v. 6 week), two levels of dietary protein (H, 230 g CP/kg v. L, 130 g CP/kg) and challenge with ETEC (+ v. -). An additional four treatments were added to test for the effects of protein source (DSMP, dried skimmed milk powder v. SOYA, soybean meal) and AGP inclusion (yes v. no) on challenged pigs of both weaning ages. At weaning (day 0), pigs were assigned to one of the experimental treatments for 2 weeks. On day 14 post-weaning, the same standard grower ration was fed to all animals until 10 weeks of age. On day 3 post weaning, challenged pigs were administered per os with 109 cfu ETEC. The ETEC challenge had a detrimental short-term effect on performance, decreasing average daily gain (ADG) (days 3 to 6; P = 0.014) in both 4- and 6-week weaned animals. Compared with their non-infected counterparts, challenged 4-week weaned pigs on the H diet demonstrated a larger decrease in ADG immediately post infection than those on the L diet, -42% and -25%, respectively (P = 0.088). This effect was smaller in the 6-week weaned pigs, -26% and -19% for the H and L diets, respectively. Pigs fed SOYA had lower (P < 0.001) daily intake and ADG (day 0 to 14) than those fed DSMP, with 6-week weaned pigs being affected to a greater extent than 4-week weaned pigs. In the absence of AGP, increasing weaning age and decreasing dietary protein level, especially in earlier weaned pigs, may help to minimise the effects of PWC on performance, particularly in sub-optimal environments.     

Performance of growing-finishing pigs fed diets containing Roundup Ready wheat (MON 71800), a non-transgenic genetically similar wheat, or conventional wheat varieties

The objective of this study was to compare growth performance and carcass and meat quality characteristics of growing-finishing pigs fed diets containing Roundup Ready wheat (MON 71800), compared with the non-transgenic genetically similar parental control wheat (MON 71900), and four commercial varieties of non-transgenic wheat (HANK, Westbred 926, Express and Zeke). The study was carried out as a split-plot design with a 2 × 6 factorial arrangement of treatments (two genders and six wheat varieties). A three-phase dietary program was used; all diets were formulated with a fixed level of wheat inclusion (70%, 80% and 85% for the Grower, Finisher I and Finisher II phases, respectively). A total of 240 commercial hybrid pigs (equal numbers of barrows and gilts) were grown from 29.5 ± 0.29 to 114.5 ± 2.23 kg live weight in single-gender pens (barrows or gilts) of five pigs (eight pens per dietary treatment) with ad libitum access to feed and water throughout the study. At the end of each dietary phase and of the test period, ultrasound measurements were taken at the 10th rib. Animals from the transgenic (MON 71800) and non-transgenic (MON 71900) treatments were harvested at the end of the study and carcass and meat quality measurements were taken. Pigs fed the six wheat varieties had similar (P > 0.05) feed intake, live weight gain, gain : feed ratio and ultrasound measures of backfat thickness and longissimus muscle area. There was a wheat variety × gender interaction (P < 0.05) for longissimus fat content. Gilts fed the transgenic wheat had higher (P < 0.05) longissimus fat content than those fed the non-transgenic control wheat; however, for barrows there was no effect (P > 0.05) of wheat variety on longissimus fat content. However, there was no effect (P > 0.05) of wheat variety on other longissimus muscle quality or composition measures. Gilts had lower (P < 0.01) feed intake, growth rate and backfat thickness, and similar gain : feed ratio (P > 0.05) compared to barrows. This study, with growing-finishing swine, suggests that the Roundup Ready wheat (MON 71800) resulted in equivalent animal performance to conventional wheat.     

Effects of intramuscular injections of folic acid on serum folates, haematological status and growth performance of growing-finishing pigs

In a first trial, 48 piglets aged 5 weeks, grouped into 6 blocks of 8 pigs each, were used to determine the effect of intramuscular injections of folic acid on serum folates, haematological status, growth performance and carcass characteristics. Each block consisted of 2 pens of 4 pigs; in one pen, pigs received, by weekly intramuscular injections, an increasing volume of a solution containing 5 mg/ml folic acid, while in the other the animals were non-injected controls. The concentration of serum folates in treated pigs was 19% higher (P = 0.005) than in controls. There was no effect of treatment (P greater than or equal to 0.29) on haemoglobin and haematocrit. During the starting period, (5-11 weeks) average daily gain was not influenced by folic acid injections but feed intake and feed conversion were decreased (P = 0.07 and P = 0.05 respectively). No effect of folic acid (P greater than or equal to 0.23) was noted from 11-23 weeks of age, suggesting that the supplement was suboptimal during the growing-finishing period. In a second trial, 72 piglets aged 9 weeks were assigned to 6 blocks of 12 animals each. The following treatments were randomly distributed in each block according to a 2 x 3 factorial design: level of feeding (restricted vs ad libitum) and weekly intramuscular injections of increasing volume of solutions containing either 0, 15 or 30 mg/ml of folic acid. The variables studied were the same as in Trial 1. Concentrations of serum folates varied quadratically (P = 0.0001) with the dose injected, a plateau being attained with injections of 15 mg/ml. There was no effect of treatment (P = 0.043) on haemoglobin and haematocrit. During the growing period (9-15 weeks), no effect (P greater than or equal to 0.72) of folic acid was noted on growth performance. However, during the finishing period (15-21 weeks), folic acid given at a dose of 30 mg/ml decreased (P = 0.006) feed intake while no effect (P greater than or equal to 0.13) of the vitamin supplementation was noted on average daily gain and feed conversion. In both trials, there was no effect (P greater than or equal to 0.21) of any treatments on carcass characteristics. These results indicate that a supplement of folic acid administered by intramuscular injections was effective in increasing concentration of serum folates of starting or growing-finishing pigs. This supplement may be associated with a decrease in feed intake.