Influence of dietary protein level, amino acid supplementation, and dietary energy levels on growing-finishing pig performance and carcass composition

Two experiments were conducted to determine the effects of feeding reduced-CP, AA-supplemented diets at two ambient temperatures (Exp. 1) or three levels of dietary NE (Exp. 2) on pig performance and carcass composition. In Exp. 1, 240 mixed-sex pigs were used to test whether projected differences in heat increment associated with diet composition affect pig performance. There were 10 replications of each treatment with four pigs per pen. For the 28-d trial, average initial and final BW were 28.7 kg and 47.5 kg, respectively. Pigs were maintained in a thermoneutral (23 degrees C) or heat-stressed (33 degrees C) environment and fed a 16% CP diet, a 12% CP diet, or a 12% CP diet supplemented with crystalline Lys, Trp, and Thr (on an as-fed basis). Pigs gained at similar rates when fed the 16% CP diet or the 12% CP diet supplemented with Lys, Trp, and Thr (P > 0.10). Pigs fed the 12% CP, AA-supplemented diet had a gain:feed similar to pigs fed the 16% CP diet when housed in the 23 degrees C environment but had a lower gain:feed in the 33 degrees C environment (diet x temperature, P < 0.01). In Exp. 2, 702 gilts were allotted to six treatments with nine replicates per treatment. Average initial and final BW were 25.3 and 109.7 kg, respectively. Gilts were fed two levels of CP (high CP with minimal crystalline AA supplementation or low CP with supplementation of Lys, Trp, Thr, and Met) and three levels of NE (high, medium, or low) in a 2 x 3 factorial arrangement. A four-phase feeding program was used, with diets containing apparent digestible Lys levels of 0.96, 0.75, 0.60, and 0.48% switched at a pig BW of 41.0, 58.8, and 82.3 kg, respectively. Pigs fed the low-CP, AA-supplemented diets had rates of growth and feed intake similar to pigs fed the high-CP diets. Dietary NE interacted with CP level for gain:feed (P < 0.06). A decrease in dietary NE from the highest NE level decreased gain:feed in pigs fed the high-CP diet; however, gain:feed declined in pigs fed the low-CP, AA-supplemented diet only when dietary NE was decreased to the lowest level. There was a slight reduction in longissimus area in pigs fed the low-CP diets (P < 0.08), but other estimates of carcass muscle did not differ (P > 0.10). These data suggest that pigs fed low-CP, AA-supplemented diets have performance and carcass characteristics similar to pigs fed higher levels of CP and that alterations in dietary NE do not have a discernible effect on pig performance or carcass composition.     

Digestibility and metabolism of copper in diets for pigs and influence of dietary copper on growth performance,intestinal health,and overall immune status: a review

The current contribution reviews absorption and metabolism of copper(Cu), Cu deficiency, Cu toxicity, Cu bioavailability, and effects of pharmacological levels of Cu on growth performance and intestinal health of pigs.Copper is a micro mineral involved in metabolic reactions including cellular respiration, tissue pigmentation,hemoglobin formation, and connective tissue development. Copper is mostly absorbed in the upper gastrointestinal tract, particularly in the duodenum, but some Cu is absorbed in the stomach. One way to evaluate the efficacy of sources of Cu is to measure relative bioavailability where responses include tissue concentrations of Cu, concentrations of metalloproteins, and enzymatic activity of animals fed test diets containing graded levels of Cu. The requirement for Cu by pigs is 5 to 10 mg/kg diet, however, Cu can be included at growth-promoting levels(i.e., 75 to 250 mg/kg diet) in diets for weanling and growing pigs to reduce post-weaning diarrhea and improve growth performance. The consistently observed improvement in growth performance upon Cu supplementation is likely a result of increases in lipase activity, growth hormone secretion, and expression of genes involved in postabsorptive metabolism of lipids. The growth-promoting effects of dietary Cu have also been attributed to its bacteriostatic and bactericidal properties because Cu may change bacterial populations in the intestine, and thereby reduce inflammation caused by pathogens. However, further research is needed to determine potential interactions between Cu and non-nutritive feed additives(e.g., enzymes, probiotics, phytobiotics), and the optimum quantity of Cu as well as the optimum duration of feeding supplemental Cu in diets for pigs should be further investigated. These gaps needs to be addressed to maximize inclusion of Cu in diets to improve growth performance while minimizing diseases and mortality.     

Efficacy of feed enzymes in pig and poultry diets containing distillers dried grains with solubles: a review

Distiller's dried grains with solubles (DDGS), a coproduct of the ethanol industry, are often used as feed material in livestock and poultry nutrition. Results of many experiments have indicated, however, that a high dietary level of DDGS can negatively affect the digestibility of nutrients and the performance of monogastric animals due to their high content of non‐starch polysaccharides (NSP). Nevertheless, using high levels of DDGS as a protein source in livestock diets can be still economically justifiable in view of the rising prices of soya bean meal and other protein sources. The aim of some recent experiments with poultry and pigs was to improve the nutritional efficacy of high‐NSP diets through the addition of feed enzymes. As presented and discussed in this review article, the efficacy of feed enzymes added to poultry and pig diets containing DDGS is not consistent and depends on many factors. However, NSP‐hydrolysing enzymes generally seemed to be more efficient than phytases in terms of the digestibility of nutrients and the growth performance of poultry and pigs fed high‐DDGS diets. For this reason, supplementation with NSP‐hydrolysing enzymes could be an efficient way to enable the use of increased levels of DDGS in poultry and pig diets.     

饲粮中添加风味剂对猪采食量的影响及其作用机理

调控猪各个阶段的采食量是动物营养研究的热点问题。风味剂主要有香味剂、甜味剂、鲜味剂,可以改善饲粮的适口性,提高猪对饲粮的喜爱程度,也可以缓解因环境变化、饲料原料改变等应激反应导致的采食量下降。猪的嗅觉系统特别发达,灵敏度很高,味觉也要比人类敏感,因此在饲粮中添加风味剂主要通过刺激猪的嗅觉和味觉来使摄食中枢兴奋,进而促进猪采食。本文综述了饲粮中添加风味剂对猪采食量的影响及其作用机理,为相关试验提供理论依据。     

Characteristics of lipids and their feeding value in swine diets

In livestock diets, energy is one of the most expensive nutritional components of feed formulation. Because lipids are a concentrated energy source, inclusion of lipids are known to affect growth rate and feed efficiency, but are also known to affect diet palatability, feed dustiness, and pellet quality. In reviewing the literature, the majority of research studies conducted on the subject of lipids have focused mainly on the effects of feeding presumably high quality lipids on growth performance, digestion, and metabolism in young animals. There is, however, the wide array of composition and quality differences among lipid sources available to the animal industry making it essential to understand differences in lipid composition and quality factors affecting their digestion and metabolism more fully. In addition there is often confusion in lipid nomenclature, measuring lipid content and composition, and evaluating quality factors necessary to understand the true feeding value to animals. Lastly, advances in understanding lipid digestion, post-absorption metabolism, and physiological processes(e.g., cell division and differentiation, immune function and inflammation); and in metabolic oxidative stress in the animal and lipid peroxidation, necessitates a more compressive assessment of factors affecting the value of lipid supplementation to livestock diets. The following review provides insight into lipid classification, digestion and absorption, lipid peroxidation indices, lipid quality and nutritional value, and antioxidants in growing pigs.     

Effects of on-farm diets for organic pig production on performance and carcass quality

An experiment was conducted to evaluate the effects of a restriction to home-grown feedstuffs and abstinence from supplementation with synthetic amino acids (AA), as ideal objectives in organic pig production according to the IFOAM standards, on growth performance and carcass characteristics. One hundred individually housed pigs were allocated to four dietary treatments and fed from growing through finishing to compare three organic barley/wheat-based diets with an isocaloric conventional diet supplemented with synthetic AA. Protein sources in the organic treatments were either faba beans, supplemented with potato protein to the same AA level as the control diet, peas and lupines, or faba beans and lupines, both without further supplementation, leading to a lower level of limited AA. Supplementation of organic diets with potato protein resulted in the same performance as supplementing the conventional diet with synthetic AA, although crude protein levels differed markedly. Pigs fed the organic diets without AA supplementation grew more slowly (P < .05) and had a decreased feed intake in the grower period (P < .05) but nearly the same feed efficiency (P > .05) as pigs fed conventional or organic diets with AA supplementation. Carcass characteristics differed in percentage of lean meat and longissimus area, being lower in the treatments without AA supplementation (P < .05). However, the intramuscular fat was higher without AA supplementation (2.9% fat) than with supplementation (1.2% fat) (P < .01). The data show that the exclusion of AA supplementation resulted in a reduction in pig performance but in an increase in intramuscular fat content; the latter is an important aspect of eating quality characteristics.     

Effect of s-methylmethionine sulphonium chloride on oesophagogastric ulcers in pigs

OBJECTIVE: To assess the value of s-methylmethionine sulphonium chloride (SMMSC) (200 mg/kg) on nutritional performance of pigs and as prevention or therapy for oesophagogastric ulcers. DESIGN: Sixty pigs from a high health status herd with continuing oesophagogastric ulcer problems were endoscopically assessed for the presence or absence of oesophagogastric ulcers. Forty-eight pigs were then selected and allocated according to an initial oesophagogastric epithelial (ulcer score) classification to replicated treatment groups in a 2 x 2 factorial design. Weight gain and feed intake were measured over 49 d, after which pigs were killed and stomachs were collected, re-examined and scored for oesophagogastric ulceration. RESULTS: There was no difference over the 49 d in weight gain, feed intake and backfat in pigs with and without SMMSC supplementation between pigs with or without fully developed oesophagogastric ulcers at the start of the study. In pigs with an initially low ulcer score, feeding SMMSC did not prevent further oesophagogastric ulcer development. No significant effect of SMMSC was apparent when final mean oesophagogastric ulcer scores were compared in pigs with existing high ulcer score. However, further analysis of the changes in individual pig oesophagogastric ulcer scores during the experiment showed that the observed reductions in scores of the high ulcer group was significantly different from all other groups. CONCLUSION: This study has indicated that supplementation of pig diets with SMMSC cannot be justified unless the slight ulcer score improvement observed could be translated to some commercial production advantage such as a reduction in pig mortalities due to oesophagogastric ulcers. This study has further confirmed the benefit of endoscopy as a tool to enable objective assessment of oesophageal gastric health.     

Processing of ingredients and diets and effects on nutritional value for pigs

A conventional diet based on corn and soybean meal fed to pigs is usually provided in a mash form and in most cases, processing other than grinding and mixing is not used. However, due to the high cost of energy in pig diets,use of high fiber ingredients such as soybean hulls, distillers dried grains with solubles, and wheat middlings has increased. High fiber concentrations in the diet usually results in reduced energy and nutrient digestibility due to the low capacity of pigs to digest fiber, which negatively impacts growth performance and carcass composition of the pigs. Feed processing technologies such as changes in grinding procedures, expansion, extrusion, pelleting, use of enzymes or chemical treatments may, however, be used to solubilize some of the cel ulose and hemicel ulose fractions that form the cel wal of plants in the ingredients, and therefore, increase nutrient availability. This may have a positive effect on energy digestibility, and therefore, also on pig growth performance and carcass composition, but effects of different feed technologies on the nutritional value of feed ingredients and diets fed to pigs are not fully understood. It has however, been demonstrated that reduced particle size of cereal grains usually results in increased digestibility of energy, primarily due to increased digestibility of starch. Extrusion or expansion of ingredients or diets may also increase energy digestibility and it appears that the increase is greater in high fiber diets than in diets with lower concentrations of fiber. Chemical treatments have not consistently improved energy or nutrient digestibility, but a number of different enzymes may be used to increase the digestibility of phosphorus, calcium, or energy. Thus, there are several opportunities for using feed technology to improve the nutritional value of diets fed to pigs.     

饲喂乳酸菌制剂对肥育猪生长性能、肉品质及风味物质含量的影响

试验旨在研究饲粮中添加乳酸菌制剂对肥育猪生长性能、肉品质及风味物质含量的影响。选取平均体重为(55±2)kg的杜×长×大三元杂猪240头,随机分为3个处理组,每组4个重复,每个重复20头试猪,公、母各半。对照组饲喂基础饲粮(玉米-豆粕型),2个试验组饲粮分别在基础饲粮中添加0.3%乳酸菌干粉和0.3%乳酸菌菌液,这2种制剂中乳酸菌含量均为1.2×10~9 CFU/g。试验期57 d,在饲养试验结束时,每个重复选择2头(1公1母)接近平均体重的试猪进行屠宰,测定胴体性状、肉品质和风味物质含量。结果表明:饲粮中添加乳酸菌干粉和乳酸菌菌液均对肥育猪的平均日增重、平均日采食量及耗料增重比无显著影响(P0.05),对肥育猪胴体直长、斜长、背膘厚、皮厚及眼肌面积也无显著影响(P0.05),对肌肉的肉色、大理石纹、pH、滴水损失率及剪切力无显著改善(P0.05);与对照组相比,饲粮中添加乳酸菌菌液显著降低背最长肌中次黄嘌呤含量(P0.05),但2个试验组肌苷酸、谷氨酸和肌内脂肪均无显著差异(P0.05)。综上所述,饲喂乳酸菌制剂对肥育猪生长性能、胴体性状和肉质无显著影响,但可降低肌肉中次黄嘌呤含量,有利于改善猪肉的风味。     

Clays as dietary supplements for swine: A review

Clays are crystalline, hydrated aluminosilicate molecules composed of alkali and alkaline earth cations along with small amounts of various other elements. The best-known are montmorillonite, smectite, illite, kaolinite, biotite and clinoptilolite. The molecules in these clays are arranged in three-dimensional structures creating internal voids and channels capable of trapping a wide variety of molecules. As a result of this structure, clay minerals are regarded as a simple and effective tool for the prevention of the negative effects of many toxic compounds. Dietary supplementation with clays has been shown to improve weight gain and feed conversion in pigs. Where improvements in performance have been noted, one of the most likely explanations for the improvement is the fact clays increase nutrient digestibility. Clays reduce the speed of passage of feed along the digestive tract which allows more time for digestion. Feeding clays also causes morphological changes in the intestinal mucosa such as an increase in villus height and an increase in the villus height to crypt depth ratio. These changes increase the surface area of the gastrointestinal tract thus increasing nutrient digestibility. Several studies have indicated that feeding clay reduces the incidence, severity and duration of diarrhea in pigs. The mechanism for the reduction in diarrhea is likely due to increases in the numbers of Bifidobacteria and Lactobacillus and decreases in Clostridia and E. coli in the small intestine of pigs fed clays. In addition, the numbers of pigs born alive and weaned, birth weight and weaning weight have been shown to be higher for sows fed clays. Several studies have indicated that clays can help mitigate the effects of mycotoxins. The aim of the present review is to focus on the various clays which have been given attention in recent research and to discuss their potential to improve pig performance.     

Clays as dietary supplements for swine:A review

Clays are crystalline,hydrated aluminosilicate molecules composed of alkali and alkaline earth cations along with small amounts of various other elements.The best-known are montmorillonite,smectite,illite,kaolinite,biotite and clinoptilolite.The molecules in these clays are arranged in three-dimensional structures creating internal voids and channels capable of trapping a wide variety of molecules.As a result of this structure,clay minerals are regarded as a simple and effective tool for the prevention of the negative effects of many toxic compounds.Dietary supplementation with clays has been shown to improve weight gain and feed conversion in pigs.Where improvements in performance have been noted,one of the most likely explanations for the improvement is the fact clays increase nutrient digestibility.Clays reduce the speed of passage of feed along the digestive tract which allows more time for digestion.Feeding clays also causes morphological changes in the intestinal mucosa such as an increase in villus height and an increase in the villus height to crypt depth ratio.These changes increase the surface area of the gastrointestinal tract thus increasing nutrient digestibility.Several studies have indicated that feeding clay reduces the incidence,severity and duration of diarrhea in pigs.The mechanism for the reduction in diarrhea is likely due to increases in the numbers of Bifidobacteria and Lactobacillus and decreases in Clostridia and E.coli in the small intestine of pigs fed clays.In addition,the numbers of pigs born alive and weaned,birth weight and weaning weight have been shown to be higher for sows fed clays.Several studies have indicated that clays can help mitigate the effects of mycotoxins.The aim of the present review is to focus on the various clays which have been given attention in recent research and to discuss their potential to improve pig performance.     

Deoxynivalenol-contaminated wheat in swine diets

Two studies were conducted using Fusarium graminearum-infected (scabby) wheat containing 6.8 ppm deoxynivalenol (DON), commonly called vomitoxin, substituted for normal wheat in starter pig diets to give varying levels of DON. After 3 wk on experimental treatments, one-half of the pigs in trial one were sacrificed to evaluate the effects of DON on heart, kidney, spleen and liver. Analyses for DON residues in these tissues were also performed. The remaining 16 pigs were placed on a conventional diet for 4 wk to evaluate effects of DON on subsequent animal performance. A different sample of scabby wheat containing 4.9 ppm of DON was substituted for sorghum grain in growing-finishing pig diets to give varying concentrations of DON. At the end of the 42-d feeding period, eight pigs were slaughtered to evaluate the effects of DON on selected tissues. Results of the three trials suggest that feed intake was reduced when DON concentrations in the swine diets neared or exceeded 1 ppm. No apparent signs of disease, including vomiting, were observed in experimental animals. Histological evaluation revealed no significant lesions or abnormalities related to DON ingestion in tissues examined. Traces of DON (8 to 28 ppb, wet weight) were found in kidney, liver, spleen and heart of starter pigs consuming the diets containing DON up to time of slaughter. No DON was found in tissues of growing-finishing pigs that were withdrawn from feed about 12 h before slaughter.     

Nutritive value of fermented and amino acid-supplemented malted sorghum sprouts for growing pigs

Two experiments were carried out to determine the effects of diets containing fermented and amino acid (AA)-supplemented malted sorghum sprout (MSP) on performance, nutrient utilisation and feed cost analysis of growing pigs. In experiment 1 (digestibility trial), 12 pigs were individually housed in metabolic crates, equipped with feeding and watering troughs which also allow for separate collection of faeces and urine. Data collection lasted for 7 days during which feed intake and faecal output were weighed, with daily storage of collected faeces at ?4 °C. Four diets, a basal diet, basal plus malted sorghum sprout (B?+?MSP), basal plus fermented malted sorghum sprout (B?+?FMSP) and basal plus amino acids plus malted sorghum sprout (B?+?AA?+?MSP), were tested. Samples of test ingredients, feed and faeces were analysed for their gross energy and proximate compositions. In experiment 2, 18 weaner pigs were used in a completely randomised design for 63 days to determine the performance and cost analysis of feeding malted sorghum sprout at 0, 100 and 200 g/kg in pig’s diet, six pigs per diet with each pig representing a replicate. Daily feed intake and weekly weight gain were determined. The prevailing cost of each feed ingredient was used to compute the feed cost and, subsequently, the feed cost analysis. Results of digestibility trial showed that there was no difference in the utilisation of the chemical constituents of B?+?MSP and B?+?AA?+?MSP diets, which were also similar to the basal diet, except the crude protein (CP) in amino acid-supplemented malted sorghum sprout diet, which was lower compared to the basal diet. B?+?FMSP was lower (P?<?0.05) in the digestibility of dry matter, organic matter and CP compared to the basal diet. The digestible energy (DE) and the fraction of gross energy utilised as DE of each diet also were not affected by fermentation and supplementation with AA. In experiment 2, the levels of MSP used did not affect (P?>?0.05) the performance and feed cost indices measured. It was concluded that MSP can be used in growing pig’s diet, without the need for fermentation and AA supplementation, at 200 g/kg level with no adverse effect on the nutritive value of the diet.     

高铜日粮对生长猪胃底腺Ghrelin分泌的影响

选用军牧1号断乳仔猪45头,随机分为3组,每组5个重复,每个重复3头,采用完全随机化设计进行生长试验,研究了不同来源(硫酸铜和蛋氨酸铜)和不同添加水平(5、125 mg/kg)的高铜日粮对猪胃底腺Ghrelin分泌的影响。结果表明:与对照组相比,日粮中添加125 mg/kg硫酸铜和125 mg/kg蛋氨酸铜组平均日增重、绝对增重、平均采食量均显著提高(P<0.05),而不同铜源间差异不显著(P>0.05);试验组胃底腺Ghrelin mRNA水平显著提高(P<0.05);血液胃泌素含量显著增加(P<0.01),并且Ghrelin mRNA水平与血液胃泌素含量呈显著正相关关系。提示高铜可促进生长猪胃底腺Ghrelin的分泌,胃泌素的分泌与胃底腺区Ghrelin的基因表达有关。     

高铜对生长猪生长性能、血清激素水平及酶活性的影响

军牧 1号生长猪 6 0头 ,体重 (19.2 6± 1.2 0 ) kg,随机分成 6组 ,公母各半。使用硫酸铜作为铜源 ,试验各组日粮铜添加质量浓度分别为 10 0、15 0、2 0 0、2 5 0、30 0 mg/kg,对照组不添加。试验期 10 0 d。测定生长性能及有关血液生化指标。结果 :(1)在日粮中添加不同水平的铜 (≥ 15 0 mg/kg和≤ 30 0 m g/kg) ,可明显提高平均日增重 (ADG) ,降低料重比 (F/G) ,但增重效应有明显的阶段性差异。前期 (0～ 6 0 d)效果优于后期 (6 0～ 10 0 d)。在整个试验期 ,试验组与对照组相比 ,ADG平均提高 9.9% ,增幅在 5 %～ 14 % ,其中以添加 2 0 0、2 5 0 mg/kg组最佳 ,分别达 72 0 .7g/d(P<0 .0 1)和72 5 .8g/d(P<0 .0 1) ;试验组 F/G平均降低 5 .4 % ,降幅为 3%～ 8.1% ,其中以添加 2 0 0、2 5 0 mg/kg组最低 ,分别为3.0 8(P<0 .0 1)和 3.0 6 (P<0 .0 1)。 (2 )试验组血清铜蓝蛋白 (CP)和铜锌超氧化物歧化酶 (Cu Zn- SOD)活性均有明显的增加。 (3)试验组血清生长激素、胰岛素和甲状腺素水平均有明显提高。结果表明 ,15 0～ 30 0 m g/kg铜添加量对 2 0～ 6 0 kg生长猪具有明显促生长作用 ,其中以 2 0 0、2 5 0 mg/kg铜添加量效果最佳 ;日粮铜水平对血清相关激素水平和酶活性的影响 ,随铜添加量的不同而呈现明显     

Effects of excess arginine on swine growth and plasma amino acid levels

One hundred seventy-six crossbred weaned pigs (4 to 5 wk old) were used in two growth trials to determine the effect of excess arginine on pig growth and plasma amino acid levels. In the first 28-d growth trial, two lysine levels (1.03 and 1.26%) and three arginine levels (.94, 1.29 and 1.63%) were used in a nested treatment arrangement. Lysine supplementation improved daily gains (P less than .05), tended to improve feed efficiency (P less than .12) and caused a general reduction in plasma essential amino acid levels. Arginine had no effect on daily gain or feed intake, but pigs fed 1.03% lysine and 1.63% arginine had reduced gain/feed (P less than .05). Arginine did not affect gain/feed of pigs fed 1.26% lysine. Plasma lysine levels were reduced (P less than .06) by excess arginine in pigs fed 1.26% lysine, but not in pigs fed 1.03% lysine. The four treatments for the second 26-d growth trial consisted of three diets containing .92% lysine and either .72, 1.10 or 1.61% arginine and a positive lysine control (1.10% lysine, .72% arginine). Lysine was the limiting amino acid in the basal diet, but arginine had no effect on daily gain, daily feed intake, gain/feed or plasma lysine levels. Plasma threonine and methionine levels were reduced by excess arginine in both experiments, while the other plasma essential amino acid levels were not affected by dietary arginine. Conclusions are that large excesses of added arginine may affect lysine utilization, but pig performance was affected only when excess arginine was combined with a lysine deficiency. The arginine levels similar to those found in grain-soybean meal swine diets had no effect on pig performance in these experiments.     

Phytate-degrading enzymes in pig nutrition

Phytate, the mixed salt of phytic acid (myo-inositol hexaphosphate), derived from plant-sourced feed ingredients is invariably present in practical diets for pigs. Typically, swine diets contain in the order of 3.0 g kg^− 1 phytate-bound phosphorus (phytate-P) but phytate concentrations are subject to variation. Importantly, phytate-P is only partially utilised by pigs because they do not generate sufficient endogenous phytase activity. Phytate-degrading enzymes, via step-wise dephosphorylation of phytate, have the capacity to liberate phytate-P, thus enhancing P absorption and reducing P excretion, which are both nutritionally and ecologically beneficial consequences. The commercial introduction of microbial phytases in 1991 has greatly magnified the interest in the roles of phytate and phytase in pig nutrition.

The capacity of microbial phytases to enhance growth performance of pigs offered diets with inadequate P levels is well documented. However, in some instances, phytase has been shown to improve performance of pigs offered P adequate diets thus phytase-induced improvements in growth performance should not be attributed entirely to increased P availability. This raises the possibility that phytase is increasing the utilisation of nutrients other than P. These so-called ‘extra-phosphoric’ effects of phytase remain controversial, particularly in relation to protein and amino acid availability. There are conflicting opinions that are reflected in the inconsistent outcomes of studies to determine the effect of phytase on ileal digestibility of amino acids and protein utilisation in pigs. In phytase amino acid digestibility assays, it seems likely the choice of chromic oxide as the dietary marker has contributed to these ambiguous results, which may be further complicated when ileal digesta samples are taken from cannulated pigs fed on a restricted, twice-daily basis. In order to resolve this critical issue, there is an urgent need to assess the impacts of selection of dietary markers, methods of ileal digesta collection and feeding regimen relative on the outcomes of phytase amino acid digestibility assays in pigs.

However, inconsistent results from phytase studies in pigs are not confined to amino acid digestibility assays. Arguably, insufficient attention has been paid to dietary substrate levels in relation to phytase inclusion from both scientific and practical standpoints. Phytate analyses are not straightforward and there is a real need to develop more accurate and rapid methods to facilitate phytate determinations. The properties of phytate vary between (and within) feed ingredients where solubility of phytate may be critical; which, in turn, is a function of gut pH in pigs. Contemporary phytases have the capacity to degrade approximately 50% of dietary phytate at the level of the ileum, which may mean higher inclusion rates are warranted. Consequently, there is scope for the development of more effective ‘second-generation’ phytate-degrading feed enzymes and their possible introduction, coupled with a better scientific understanding of relevant fundamental issues, will ensure that phytate-degrading enzymes will contribute to viable and sustainable pig production to an even greater extent in the future.     

Growth performance and intestinal morphology responses in early weaned pigs to supplementation of antibiotic-free diets with an organic copper complex and spray-dried plasma protein in sanitary and nonsanitary environments

The objective of this study was to determine the effects of addition of spray-dried plasma protein (SDPP) and Cu to nonmedicated diets on growth performance and intestinal morphology in weaned pigs reared in sanitary or nonsanitary environments. Weanling pigs (n = 192, 18 +/- 2 d of age, 6.0 +/- 0.2 kg of BW) were assigned to 8 treatments arranged factorially, including 2 dietary levels of SDPP (0 or 6% for the initial 10 d), 2 levels of added dietary Cu (0 or 200 ppm for the entire 35-d experiment), and 2 pen sanitation conditions (sanitized or nonsanitized before pig placement). The nonsanitary pen condition was created by 3 applications of swine manure slurry to all pen surfaces in 1 room and not washing or disinfecting. In an identical adjacent room, sanitary pens were washed and disinfected before weaning. There were 4 pigs per pen, and feed and water were available ad libitum. Growth performance was determined at the end of each diet formulation phase (d 10, 20, and 35 after weaning). On d 10, 1 pig per pen was euthanized, and cross sections of duodenum, jejunum, and ileum were collected for microscopic assessment of mucosal morphology. During the initial postweaning period, SDPP, and Cu supplementation improved ADG and ADFI (P < 0.001). A trend for an interaction of sanitation x dietary SDPP (P = 0.07) was observed for G:F, with a positive response to the supplement in nonsanitary pens but no response in sanitary pens. There were no interactions of SDPP and Cu for any performance variables (P > 0.30). By d 35, there were no main or interaction effects of treatment on ADG or G:F (P > 0.17). Pen sanitation condition produced morphological effects, with shorter villous length and less crypt depth observed in each intestinal segment for pigs reared in the nonsanitary pens (P < 0.05), but these effects must be considered conditional based on the potential confounding influence of separate nursery rooms. In the duodenum, reduced crypt depth with Cu supplementation (P = 0.01) and a tendency for greater villous length with SDPP supplementation (P = 0.09) were observed. In this study, SDPP and Cu supplementation improved pig growth performance during the initial 10-d postweaning. These modifications to nonmedicated diets acted independently with regard to their impacts on postweaning performance and, therefore, could have additive effects.     

化学益生素在猪生产中的应用潜力

欧洲猪生产中抗菌饲料添加剂的禁用及对猪胃肠道微生物发酵的有益调控的研究 ,促进了非消化性寡糖的研究。非消化性寡糖 ,作为化学益生素最显著的作用就是对有益菌 ,如双歧杆菌的特殊的刺激作用 ,并通过竞争性排斥病源微生物如大肠杆菌的生长 ,抑制有害菌的作用 ,从而有助于保持胃肠道合适的菌丛。然而 ,猪日粮中包含的特异性非消化性寡糖对微生物生态系统、消化过程及动物的生产性能的作用存在着争议。由于大多数非消化性寡糖在胃和小肠中快速的发酵速率 ,因此上段消化道的糖分解活力不能在整个消化道中维持。若使用在整个胃肠道部分包括大肠能够发酵的非消化性寡糖的复合物可延长化学益生的作用 ,并且证明其作为饲料添加剂在猪饲料中的使用是有效的     

Effects on performance of growing pigs fed diets containing different levels of dried cashew pulp

The purpose was to investigate the use of dried cashew pulp (DrCP), the sun-dried residue after juice has been extracted from the cashew apple, as a feed ingredient in growing pig diets. The growth rate, feed intake, feed to gain ratio and cost of gain of grower pigs fed diets containing 0 (0DrCP), 100 (100DrCP), 150 (150DrCP) or 200 (200DrCP) g kg⁻¹ of dried cashew pulp was investigated in a feeding trial set up as a Completely randomized design with 4 treatments replicated 3 times and lasting 112 days. There were no significant differences (P > 0.05) among treatments in the parameters measured. It was concluded that dried cashew pulp could be used in growing pig diets up to a level of 200 g kg⁻¹ without any deleterious effects. Future work will look at higher levels of DrCP inclusion in the diets of growing pigs.