Estimation of Digestible Energy Values of Plant Protein Supplement in Pig

[Objective] The aim of the study was to establish the effective and accurate formulas for estimating the digestible energy （DE） values of plant protein supplement in pig. [Method] By difference method with different amount of alternative feeds （20% -50%）, two4 x4 Latin- square-designed trials were taken on eight castrated male pigs [ Yorkshire x Landrace x Neijiang pig, initial body-weight： （46 ±2） kg ] to deter- mine the apparent digestible energy （ADE） of the eight kinds of plant protein supplement commonly used in China, that is, corn gluten meal （sol.）, soybean meal （ sol. ）, fababean, pea, rapeseed meal （ sol. ）, sesame meal （ sol. ）, rapeseed meal （ exp. ） and cotton seed meal （sol.）. [Resultl （1） Fiber was the most important factor to estimate the ADE of plant protein supplement in pigs, and ADF was the best one. （2） The most effective equations were as below： （ 1 ） OE （kJ/kg DM） = 14 741.86 - 185.01ADF＋54.01SCHO＋22.45CP （ R =0.988,RSD= 67.9,P〈0.01 ） ; （2） DE （kJ/kg DM） =22 223.26 -209.58ADF＋26.79SCHO-1.09GE （ Ff =0.989,RSD=66.9, P〈0.01 ） . [Conclusion] The accurate, practical and specific regression equations were established for DE prediction of plant protein supplement in pig.

Effects of the Ratio of Lysine to Digestible Energy Level in the Diet on the Expression and Activity of Transcription Factors Involved in Lipogenesis in Rongchang Pigs

This study was conducted to determine the effects of varying the ratio of lysine to digestible energy level On the activity and gene expression of the transcription factors peroxisome proliferator-activated receptor-γ （PPAR-γ） and CCAAT/enhancer-binding protein-or and -β （C/EBP-α and C/EBP-β） to better understand the regulatory mechanisms controlling adipogenesis in fat and muscle tissue of the Rongchang pig. A total of 144 castrated Rongchang pigs weighing approximately 20 kg were used in a 2 ×2 factorial design experiment. Diets were formulated to contain a high （14.22 MJ/kg） or low （13.11 MJ/kg） digesti- ble energy （DE） level. Within each energy level, pigs were fed diets containing a high lysine： DE ratio （0.67,0. 53, or 0. 42） or a low lysine ： DE ratio （0.49,0.38 ,or 0.30） during the periods from 20 to 50 kg, 50 to 80 kg, and 80 kg to slaughter, respectively. Each diet was fed to six replicate pens, each containing nine pigs. When the pigs reached average live weights of 20,35,60, and 90 kg ,one pig from each of the replicates was chosen at random and slaughtered.Samples of back fat and longissimus dorsi muscle were collected for the assessment of transcriptional factor. The results showed that feeding a high DE level significantly increased （ P 〈 0.05 ） the expression of PPAR-T at 60 and 90 kg in muscle and at 35,60, and 90 kg in back fat. Energy level also significantly increased the expression of C/EBP-fl at 35 and 60 kg in both muscle and back fat （ P 〈 0.05 ）. Higher dieta- ry lysine increased the expression of C/EBP-fl in muscle at 35 and 90 kg （ P 〈 0.05）, but decreased the expression in back fat at 35 （P = 0.03 ） and 90 kg （P = 0.09）. The lysine level increased the expression of PPAR-3~ in muscle at 60 kg only. Energy level and lysine content had no significant effects on promote the activity of PPAR-γ, C/EBP-α, or C/EBP-β either in muscle or in back fat at any level of the body weights tested. Collectively, these data indicated that dietary energy density and lysine level were equally important for lipid deposition in muscle tissue, whereas dietary energy density was more important than lysine level for fat deposition in fat tissue.

Use of near-infrared reflectance spectroscopy for the rapid determination of the digestible energy and metabolizable energy content of corn fed to growing pigs

Background： The ability of near-infrared reflectance spectroscopy（NIRS） to determine the digestible energy（DE）and metabolizable energy（ME） content of corn fed to growing pigs was tested. One hundred and seventeen corn samples, comprising different planting regions and varieties were collected from all over China in a three-year period. The samples were randomly split into a calibration set（n = 88） and a validation set（n = 29）. The actual and calculated DE and ME content of the corn samples was determined by digestion-metabolism experiments and the prediction equations of Noblet and Perez（J Anim Sci. 71：3389–98,1993）. The samples were then subjected to NIRS scanning and calibrations were performed by the modified partial least square（MPLS） regression method based on77 different spectral pre-treatments. The NIRS equations based on the actually determined and calculated DE and ME were built separately and then validated using validation samples.Results： The NIRS equations obtained from actually determined DE, the coefficient of determination for calibration（RSQcal）, cross-validation（R^2CV）, and validation（RSQv） were 0.89, 0.87 and 0.86, and these values for determined ME were 0.87, 0.86 and 0.86. For the NIRS equations built from calculated DE, the RSQcal, R^2CV, and RSQvvalues were 0.88, 0.85 and 0.84, and these values for calculated ME were 0.86, 0.84 and 0.82. Except for the equation based on calculated ME（RPD_v= 2.38, 〈 2.50）, the other three equations built from actually determined energy and calculated DE produced good prediction performance（RPD_vranging from 2.53 to 2.69, 〉 2.50） when applied to validation samples.Conclusion： These results indicate that NIRS can be used as a quantitative method for the rapid determination of the available energy in corn fed to growing pigs, and the NIRS equations based on the actually determined energy produced better predictive performance than those built from calculated energy values.

Accuracy of predicting metabolizable energy from in vitro digestible energy determined with a computer-controlled simulated digestion system in feed ingredients for ducks

Two experiments were conducted to study the accuracy of predicting true metabolizable energy(TME)of ingredients for ducks from in vitro digestible energy(IVDE)determined with a computer-controlled simulated digestion system.Experiment 1 was to establish TME prediction models from the IVDE of 9 energy feed ingredients and 12 protein feed ingredients using regression analysis.Experiment 2 was to validate the accuracy of the predicted ME of 10 ingredients randomly selected from Exp.1.Ten diets were formulated with 2 to 6 of 10 ingredients.Dietary in vivo TME values were compared with calculated values based on the TME predicted in Exp.1.In Exp.1,the correlation coefficients between TME and IVDE were 0.9339(P<0.05)in 9 energy feed ingredients and 0.8332(P<0.05)in 12 protein feed ingredients.No significant difference was observed on the slope and intercept of TME regression models between 9 energy feed ingredients and 12 protein feed ingredients.Therefore,the regression model of TME on IVDE for 21 feed ingredients was TME=0.7169×IVDE+1,224(R^(2)=0.7542,P<0.01).Determined and predicted TME differed by less than 100 kcal/kg of DM in 11 ingredients,and the difference ranged from 100 to 200 kcal/kg of DM in 5 ingredients.However,the difference between determined and predicted TME varied from 410 to 625 kcal/kg of DM in rice bran,rapeseed meal,corn gluten meal,and citric acid meal.In Exp.2,the determined and calculated TME were comparable(3,631 vs.3,639 kcal/kg of DM)and highly correlated(r=0.9014;P<0.05)in 10 diets.Determined and calculated TME differed by less than 100 kcal/kg of DM in 7 diets and by 106 to 133 kcal/kg of DM in 3 diets.These results have demonstrated that TME can be accurately predicted from IVDE in most feed ingredients,but it is less accurate for rice bran,rapeseed meal,corn gluten and citric acid meal.

Digestible energy and metabolizable energy contents of konjac flour residues and ramie in growing pigs

The objectives of this study were to determine: 1) the effects of konjac flour residues and ramie on digestible energy(DE), metabolizable energy(ME) and apparent total tract digestibility(ATTD) of nutrients in diets fed to growing pigs, 2) the DE and ME contents of konjac flour residues and ramie.Thirty barrows were allotted to 1 of 5 treatments with 6 replicates per treatment.The 5 diets include a corn-soybean meal basal diet(CTL), konjac flour residues diets containing 15% konjac flour residues(LK)or 30% konjac flour residues(HK), and ramie diets containing 15% ramie(LR) or 30% ramie(HR).The experiment lasted 19 days, including 7 days for cage adaptation, 7 days for diet adaptation, and 5 days for total feces and urine collection.The energy values and ATTD of nutrients in each diet were determined,and DE and ME contents of konjac flour residues and ramie were calculated.The results showed that consumption of konjac flour residues significantly increased(P < 0.01) the fecal moisture content compared with the ramie treatment.The LK, HK and HR diets had lower(P < 0.01) DE values compared with the CTL diet.The HR diet had greater(P < 0.01) DE value compared with the HK diet.The LK and LR diets showed greater(P < 0.01) ATTD of DM, OM, GE and CP compared with the HK and HR diets.The HK diet had the lowest(P < 0.01) ATTD of ether extract(EE) among the 5 diets.No differences were observed for the ATTD of NDF and ADF among the 5 diets.Moreover, the DE and ME values of konjac flour residues under 2 inclusion levels(15% and 30%) were 11.66, 11.87 MJ/kg and 10.41, 10.03 MJ/kg, respectively.The corresponding values for ramie were 13.27, 13.16 MJ/kg and 13.07, 12.82 MJ/kg, respectively.In conclusion, the differences in fecal moisture content and the ATTD of EE among the 5 diets were mainly due to the different chemical compositions of konjac flour residues and ramie.Compared with konjac flour residues, ramie has greater DE and ME values under the same inclusion level.

Predicting corn digestible and metabolizable energy content from its chemical composition in growing pigs

Background： The nutrient composition of corn is variable. To prevent unforeseen reductions in growth performance, grading and analytical methods are used to minimize nutrient variability between calculated and analyzed values. This experiment was carried out to define the sources of variation in the energy content of corn and to develop a practical method to accurately estimate the digestible energy （DE） and metabolisable energy （ME） content of individual corn samples for growing pigs. Twenty samples were taken from each of five provinces in China （Jilin, Hebei, Shandong, Liaoning, and Henan） to obtain a range of quality. Results： The DE and ME contents of the 100 corn samples were measured in 3.5.3 ±1.92 kg growing pigs （six pigs per corn sample）. Sixty corn samples were used to build the prediction model; the remaining forty samples were used to test the suitability of these models. The chemical composition of each corn sample was determined, and the results were used to establish prediction equations for DE or ME content from chemical characteristics. The mean DE and ME content of the 100 samples were 4,053 and 3,923 kcal/kg （dry matter basis）, respectively. The physical characteristics were determined, as well, and the results indicated that the bulk weight and 1,000-kernel weight were not associated with energy content. The DE and ME values could be accurately predicted from chemical characteristics. The best fit equations were as follows： DE, kcal/kg of DM = 1062.68 ＋ （49.72 ×EE） ＋ （0.54 × GE） ＋ （9.1 ] x starch）, with R^2 = 0.62, residual standard deviation （RSD） = 48 kcal/kg, and P 〈 0.01; ME, kcal/kg of dry matter basis （DM） = 671.54 ＋ （0.89 ×DE） - （5.57 × NDF） - （191.39 ×ash）, with R^2 = 0.87, RSD = 18 kcal/kg, and P〈 0.01. Conclusion： This experiment confirms the large variation in the energy content of corn, describes the factors that influence this variation, and presents equations based on chemical measurements that may be used to predict the DE and ME content of individual corn samples.

Chemical composition,energy and amino acid digestibility in double-low rapeseed meal fed to growing pigs

Background： The nutritional value of rapeseed meal may be variable due to the variation of its chemical composition. And a precise understandin9 of the nutritional value of an ingredient is beneficial for the accurate diet formulation and reduction of feed costs. This study was conducted to determine the chemical composition, dicjestible energy （DE） and metabolizable enercjy （ME） content, and apparent ileal digestibility （AID） and standardized ileal dicjestibility （SID） of amino acids （AA） for growincj pigs. Thirteen solvent-extracted double-low rapeseed meal （DLIRSM） samples were obtained from the main double-low rapeseed producing areas in China. Methods： The DE and ME contents of the 13 DLRSM samples were measured in cjrowin9 pigs （six pigs per DLRSM sample, average initial body weicjht （BW） =48.3 kg）. The AID and SID of AA of 10 DLRSM samples were determined in 12 crossbred barrows （average initial BW = 35.3 kcj） by using two 6 x 6 Latin square designs. Each Latin square comprised one N-flee diet and 5 DLRSM test diets. Results： The chemical composition of DLRSM varied among samples, and the coefficient of variation was greater than ]0 % for ether extract （EE）, neutral detergent fiber （NDF）, acid detergent fiber （ADF）, calcium （Ca）, and total 91ucosinolates. The AA content of DLRSM varied among samples especially for lysine （Lys） and methionine （Met）. On a dry matter （DM） basis, the apparent total tract digestibility （ATFD） of gross energy （GE）, the DE and ME and the ME：DE ratio of DLRSM averaged 62.39 %, 2862 kcal/k9 and 2723 kcal/kcj, and 94.95 %, respectively. The mean value of S1D of Lys was 70.52 % which varied from 66.54-76.54 %. The SID of crude protein （CP）, Met, and threonine （Thr） averaged 72.81%, 82.41%, and 69.76 %, respectively. Conclusions： There was great variability in chemical composition especially in the concentration of EE, NDF and ADF, but no significant differences in energy content of the DLIRSM samples were observed. In addition, the AID and SID of all AA were relatively similar amoncj DLRSM samples except for that of Lys.

Energy requirements of Dorper×thin-tailed Han crossbred ewes during non-pregnancy and lactation

This experiment was conducted to investigate the energy requirement of Dorper×thin-tailed Han crossbred ewes during non-pregnancy and lactation. Fifteen ewes after parturition were randomly assigned to three treatments： ad libitum（100%） feed intake and 80 or 60% ad libitum intake, and another nine non-pregnant ewes were assigned to a blank control group. Digestibility trials were performed in the non-pregnant ewes and in the lactating ewes on the 20 th, 50 th, and 80 th d of lactation. In parallel with the digestibility trial, a respirometry experiment was conducted to determine the methane and carbon dioxide production with an open-circuit respirometry system that was equipped with respiratory chambers. The net energy（NE） and metabolizable energy（ME） requirements for maintenance and growth were calculated using the carbon and nitrogen balance method. The results revealed that the carbon（C） and nitrogen（N） excretions and energy losses at faeces and urine, as well as the output of methane and CO2, increased significantly with decreasing feed intake（P〈0.01）. The apparent digestibilities of C in th e stages of non-pregnancy and early, middle and late lactation were 55.8–58.3%, 62.5–73.8%, 64.8–71.3%, and 61.7–65.0%, respectively, and the apparent digestibilities of N were 45.2–51.3%, 73.7–82.7%, 72.8–80.5%, and 73.6–76.5%, respectively. The corresponding energy apparent digestibilities were 52.0–56.3%, 60.7–76.6%, 61.0–68.8%, and 61.4–67.7%, respectively. The ME/DE（digestible energy） values were 79.5–85.9%, 79.4–83.5%, 81.0%–85.3% and 78.6–82.9%, respectively. The maintenance requirements of NE, ME, and the efficiencies of ME utilisation for maintenance during the stages of non-pregnancy and early, middle and late lactation were 215.5, 253.1, 247.7, and 244.7 k J kg^（–1） BW0.75 d, and 372.4, 327.1, 320.9, and 362.0 k J kg^（–1） BW0.75 d, and 0.58, 0.77, 0.77, and 0.68, respectively. The ME requirement for the growth of non-pregnant ewes was 31.3 MJ kg^（–1） BW gain.

A meta-analysis of the effects of energy intake on risk of digestive cancers

AIM:To quantitatively assess the relationship between energy intake and the incidence of digestive cancers in a meta-analysis of cohort studies.METHODS:We searched MEDLINE,EMBASE,Science Citation Index Expanded,and the bibliographies of retrieved articles.Studies were included if they reported relative risks(RRs) and corresponding 95% CIs of digestive cancers with respect to total energy intake.When RRs were not available in the published article,they were computed from the exposure distributions.Data were extracted independently by two investigators and discrepancies were resolved by discussion with a third investigator.We performed fixed-effects meta-analyses and meta-regressions to compute the summary RR for highest versus lowest category of energy intake and for per unit energy intake and digestive cancer incidence by giving each study-specific RR a weight that was proportional to its precision.RESULTS:Nineteen studies consisting of 13 independent cohorts met the inclusion criteria.The studiesincluded 995 577 participants and 5620 incident cases of digestive cancer with an average follow-up of 11.1 years.A significant inverse association was observed between energy intake and the incidence of digestive cancers.The RR of digestive cancers for the highest compared to the lowest caloric intake category was 0.90(95% CI 0.81-0.98,P < 0.05).The RR for an increment of 239 kcal/d energy intake was 0.97(95% CI 0.95-0.99,P < 0.05) in the fixed model.In subgroup analyses,we noted that energy intake was associated with a reduced risk of colorectal cancer(RR 0.90,95% CI 0.81-0.99,P < 0.05) and an increased risk of gastric cancer(RR 1.19,95% CI 1.08-1.31,P < 0.01).There appeared to be no association with esophageal(RR 0.96,95% CI 0.86-1.07,P > 0.05) or pancreatic(RR 0.79,95% CI 0.49-1.09,P > 0.05) cancer.Associations were also similar in studies from North America and Europe.The RR was 1.02(95% CI 0.79-1.25,P > 0.05) when considering the six studies conducted in North America and 0.87(95% CI 0.77-0.98,P < 0.05) for the five studies from Europe.CONCLUSION:Our findings suggest that high energy intake may reduce the total digestive cancer incidence and has a preventive effect on colorectal cancer.

Effects of graded fiber level and caecectomy on metabolizable energy value and amino acid digestibility in geese

This study was carried out to evaluate the effects of graded levels of fiber from rice hull and the caecectomy on metabolizable energy（ME） and amino acid digestibility（AAD） in 42 Wuzong geese（21 intact and 21 caecectomized）. The experiment was a 3×2 factorial randomized design with 3 fiber levels and 2 treatments of geese（caecectomized and intact）. Each of the 3 diets was tube-fed（60 g） to 7 caecectomized and 7 intact adult Wuzong geese that had been fasted for 24 h. Excreta were collected for the next 48 h. The same geese were also fasted for estimation of endogenous losses of amino acids（AA） and energy after short period recovery. AA content and metabolizable energy value were determined in the excreta. In general, significant effects were found for fiber levels on apparent digestibility of Thr, Leu, Pro, Glu,Val, Ala and total AA（P〈0.05）. Apparent metabolizable energy（AME） and true metabolizable energy（TME） were both significantly influenced by increased fiber levels（P〈0.01）. Compared with caecectomized geese, markedly increases of AME and TME were found in intact geese（P〈0.01 for AME and P 〈0.05 for TME）, but no difference in the AAD were found between intact and caecectomized geese（P〉0.05）, except for Lys and Try（P〈0.05）. These observations suggested that dietary fiber level played an important role in digestibility of AAD and ME. Intact geese should be chosen for the nutrient evaluation of feedstuffs in practice, resulting from the significant difference between caecectomized and intact geese.

An automatically progressed computer-controlled simulated digestion system to predict digestible and metabolizable energy of unconventional plant protein meals for growing pigs

The objective of this experimentwas to develop a new computer-controlled simulated digestion system to predict the digestible energy(DE)and metabolizable energy(ME)of unconventional plant protein meals for growing pigs.Nine meals tested included 1 source of rapeseed meal,4 sources of cottonseed meal,2 sources of sunflower meal,and 2 sources of peanut meal.Twenty growing pigs(Duroc[LandraceLarge White])with an initial body weight(BW)of 41.7±2.6 kg were allotted to a replicated 103 incomplete Latin square design to determine the DE and ME of 1 basal diet and 9 experimental diets formulated with 9 unconventional plant protein meals.The DE andMEvalues of unconventional plant protein meals were calculated by the difference method.The in vitro digestible energy(IVDE)of 1 basal diet,9 experimental diets,and 9 unconventional plant protein meals were determined with 5 replicates of each sample in a complete randomized arrangement.The IVDE/DE or IVDE/ME ranged from 0.96 to 0.98 or 1.00 to 1.01,and the correlation coefficient between IVDE and DE or MEwas 0.97 or 0.98 in 10 experimental diets.Accordingly,the IVDE/DE or IVDE/ME ranged from 0.86 to 1.05 or 0.96 to 1.20,and the correlation coefficient between IVDE and DE orME was 0.92 or 0.91 in 9 unconventional plant protein meals.The coefficient of variation(CV)of IVDE was less than that of DE and ME in the experimental diets(0.43%,0.80%,and 0.97%for CV of IVDE,DE and ME,respectively)and unconventional plant protein meals(0.92%,4.84%,and 6.33%for CV of IVDE,DE and ME,respectively).The regression equations to predict DE from IVDE in 10 experimental diets and 9 unconventional plant protein meals were DE=0.8851IVDE t539(R^(2)=0.9411,residual standard deviation[RSD]=23 kcal/kg DM,P<0.01)and DE=0.9880IVDE t 166(R^(2)=0.8428,RSD=182 kcal/kg DM,P<0.01),respectively.Therewas no statistical difference in the slopes(P=0.82)or intercepts(P=1.00)of these 2 equations.Thus,10 diets and 9 unconventional plant protein meals were pooled to establish the regression equation of DE on IVDE as:DE=0.9813IVDE t187(R^(2)=0.9120,RSD=118 kcal/kg DM,P<0.01).The regression equations to predictME from IVDE in 10 experimental diets and 9 unconventional plant protein meals were ME=0.9559IVDE t146(R^(2)=0.9697,RSD=18 kcal/kg DM,P<0.01)and ME=0.9388IVDEt3(R^(2)=0.8282,RSD=182 kcal/kg DM,P<0.01),respectively.Therewas no statistical difference in slopes(P=0.97)but significant difference between the intercepts(P=0.02)of these 2 equations.Our results indicate IVDE has similar response to the DE but different response to the ME in 10 experimental diets and 9 unconventional plant protein meals.Therefore,IVDE is moresuitable to predict DE than ME of diets and unconventional plant protein meals for growing pigs.

Effect of variety and drying method on the nutritive value of corn for growing pigs

Background：This experiment was conducted to determine the nutritive value of corn from the north of China for growing pigs.The experiment examined corn variety（LS1,LS2,LS3 and LS4）grown in one location,drying method（sun dried and artificially dried）and different drying temperatures.Corn harvested at 20-25%moisture was dried to about 12%moisture by sun drying and artificially drying at 80,100,or 120℃ in a fluidized bed dryer.Ninety-six barrows（average BW of 33.4 ± 2.7 kg）were housed in individual metabolism crates to facilitate separate collection of feces and urine.A five-day collection period followed a seven-day diet acclimation period.Results：The results indicated that variety significantly influenced（P〈0.01）the 1,000 kernel weight of corn but not the bulk weight.Variety also influenced the available energy content（digestible energy of dry matter,P〈0.01;metabolisable energy of dry matter,P〈0.01）and digestibility of organic matter（P〈0.01）,as well as dry matter（P〈0.01）and gross energy（GE）content（P〈0.02）.The drying method of corn significantly influenced the 1,000 kernel weight（P〈0.01）,bulk weight（P〈0.01）and digestibility of ether extract（EE）（P〈0.01）.No effect of drying temperature on the digestibility of organic matter,dry matter（DM）,crude protein（CP）,neutral detergent fiber（NDF）,acid detergent fiber（ADF）and gross energy was observed,but gelatinization（P〈0.05）and test weight（P〈0.01）decreased with an increase in temperature.Conclusions：Variety has a significant impact on the nutritive value of corn for growing pigs,and greater attention needs to be paid to these influences in the assignment of the nutritive value of corn given to growing pigs.

Growth Dynamics and Optimal Harvesting Stage of Two Forage Maize Varieties

SAUMZ 1 and SAUMZ 2 are two forage maize varieties reproduced by distant hybridization.In a randomized block experiment,their fresh forage yield and dry matter yield were investigated on the basis of growth period,leaf stage,and effective accumulated temperature.The nutritional components were measured in a near infrared diffuse reflectance spectroscopy.Referring to the concept of forage grading index,a formula was constructed to calculate the total digestible energy.The investigated characters and indexes were adapted to suitable models of growth dynamics.The results showed that these two varieties have strong heterosis in fresh forage yield,dry matter yield,and total digestible energy.Their growth dynamics were adapted to Logistic models described by general equation y=k/（1＋ae-bx）.The forage grading indexes of these two varieties were decreased linearly along with the increasing of their leaf stage.The stopping point of fast growing period of total digestible energy estimated on the basis of leaf stage was suggested to be used as optimal harvesting stage of forage maize.The optimal harvesting stage was estimated to be tasseling stage for SAUMZ 1 and 19.50-leaf stage for SAUMZ 2.

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.

Dietary free fatty acids complex with amylose creating another form of resistant starch: Gastrointestinal formation with fowl and swine

Fat added to poultry and swine feeds often contains abundant free fatty acids(FFA)that can impair digestible energy(DE).Placement of the fatty acid(FA)hydrocarbon chain in the helix core reformed from amylose creates a complex of both nutrients.Resulting modifications create a new structure termed the V-helix that becomes resistant toα-amylase.Granules in grain naturally contain minimal amounts of these complexes with more being generated during food manufacturing when moisture and heat release amylose in the presence of FFA.A paucity of FFA usually exists in complete feeds without sources of poorquality fat.Animal fats and by-product meals from rendering are prominent in their saturated FFA content which favorably complex within the helix.V-helix-FA complexes may arise during their concurrent encounter of FFA together with amylose during feed manufacture,particularly pelleting.FFA in the gastrointestinal tract(GIT)are speculated to further form complexes when present together with amylose.Although amylose may be dissolved in the gastric and small intestinal milieu,FFA separately coalesce into hydrophobic fat droplets along with other dietary lipids.Formation of complexes is likely restricted until FFA are released into the aqueous phase during fat digestion.Althoughα-amylase may be prominent,V-helix-FA complexes being resistant to enzymic attack pass into the large intestine.Subsequent microbial catabolism of V-helices may generate volatile fatty acids that are absorbed by the mucosa;however,an inability to use FFA once released leads to their excretion and basis for decreased DE.Immature microbial populations with young animals usually lack the capacity to fully catabolize the V-helix,further extending the loss in DE.