Research Reports

Pork products have digestible indispensable amino acid scores that are greater than 100, but processing does not always increase amino acid scores

Pork is the most widely consumed animal meat in the world accounting for approximately 40% of the total global meat intake. Pork almost always undergoes some degree of processing prior to consumption. Consequently, thermal processing induces modification to the 3-dimentional structure of proteins, which may lead to increased digestibility of amino acids (AA).

Protein quality is evaluated in human foods by the digestible indispensable amino acid score (DIAAS) methodology, which can be described as the digestibility of individual dietary indispensable AA (IAA) compared with the same IAA in 1 of the 3 reference protein patterns established by the Food and Agriculture Organization of the United Nations (FAO). Values for DIAAS of bovine meat cooked by various techniques have been determined, yet to our knowledge, there are no reported DIAAS values for pork products and the IAA digestibility of pork after processing has not been reported.

Therefore, the objective for the present work was to determine DIAAS values for pork products, and to test the hypothesis that processing may increase protein quality.

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Excessive heat treatment of double-low rapeseed meal reduces not only amino acid digestibility but also concentrations of metabolizable energy when fed to growing pigs

Double-low rapeseed meal (RSM) is currently used as a protein ingredient in animal diets. Heat treatment of RSM at varying processing conditions removes the residual hexane and efficiently reduces the glucosinolate content. However, variations in heat processing temperatures and duration of heat treatment may result in Maillard reactions, resulting in the formation of sugar-amino acid complexes. Maillard reaction products result in reduced standardized ileal digestibility (SID) of amino acids (AA), with Lys being the most sensitive AA. However, there is limited information about how heating affects the concentration of digestible energy (DE) and metabolizable energy (ME). Therefore, the objective of this experiment was to test the hypothesis that both the degree of heating and the time that heat is applied will affect the concentration of DE and ME and the SID of AA in double-low RSM fed to growing pigs.

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Crystalline amino acids in diets used to determine the standardized ileal digestibility of amino acids in feed ingredients fed to pigs do not influence calculated values for amino acid digestibility

Protein and amino acids quality in feed ingredient is most correctly evaluated by determining the standardized ileal digestibility (SID) of crude protein (CP) and amino acids. Experiments to determine the SID of CP and amino acids in feed ingredients often utilize semi-synthetic diets that contain the test ingredient as the sole source of CP and amino acids. Therefore, the CP and amino acid supply from experimental diets do not always meet the requirement for standardized ileal digestible amino acids by pigs and, therefore, pig growth is often limited in these experiments.

Crystalline amino acids are believed to be rapidly absorbed and 100% digestible. Addition of crystalline amino acids to diets during the adaptation or collection phase is, therefore, believed not to influence values for SID of amino acids in the test feed ingredient, but this has not been experimentally verified. Therefore, an experiment was conducted to test the hypothesis that addition of crystalline amino acids to diets during the adaptation or collection periods of digestibility studies will not influence calculated values for SID of CP and amino acids in corn and soybean meal. 

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Influence of the concentration of dietary digestible calcium on growth performance, bone ash, and abundance of genes involved in intestinal absorption of calcium in pigs from 11 to 25 kg fed diets with different concentrations of digestible phosphorus

Requirements for P for growing pigs are expressed as the requirement for standardized total tract digestible (STTD) P, whereas requirements for Ca are usually expressed as requirements for total Ca. It is, however, recognized that diets for pigs are most accurately formulated based on a STTD Ca:STTD P ratio, and recent work has generated values for STTD of Ca in most Ca containing feed ingredients, which makes it possible to formulate diets based on STTD Ca.

Recent data from the University of Illinois have indicated that if STTD P is at the requirement, a ratio between STTD Ca and STTD P that is less than 1.35:1, 1.25:1, and 1.10:1 maximizes growth performance of pigs from 25 to 50 kg, 50 to 85 kg, and 100 to 130 kg, respectively. However, the STTD Ca:STTD P ratio needed to maximize bone ash is greater than the ratio needed to maximize growth performance. An attempt to estimate the requirement for STTD Ca by pigs from 11 to 25 kg was also made, but due to a reduction in ADG and G:F as dietary Ca increased, an optimal STTD Ca:STTD P ratio could not be estimated.

Calcium may be absorbed by transcellular or paracellular transport. Transcellular transport is the primary route if dietary Ca is low, but if dietary Ca is adequate or high, Ca is mainly absorbed using the paracellular route via the tight junctions. However, there are limited data demonstrating effects of dietary Ca concentration on abundance of genes related to transcellular and paracellular transport of Ca in the small intestine of pigs.

Therefore, the objectives of this experiment were to test the hypotheses that a STTD Ca:STTD P ratio less than 1.40:1 maximizes growth performance of pigs from 11 to 25 kg and that increasing dietary Ca downregulates abundance of genes related to transcellular absorption of Ca and tight junction proteins in the small intestine.

 

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Nutritional value of high-lysine sorghum, red sorghum, white sorghum, and yellow dent corn fed to growing pigs

Sorghum is used as an alternative to corn due to its lower cost and wide availability. However, conventional sorghum contains high concentration of tannin and phytate, which act as antinutritional factors. Use of microbial phytase may hydrolyze phytate and subsequently improve P absorption. High-lysine sorghum is a new variety of sorghum which may be comparable to other cereal grains and may serve as alternative to corn for pigs. However, there are at this point no data for effects of adding phytase to diets containing sorghum and no data to demonstrate the nutritional value of high-lysine sorghum.

Therefore, 2 experiments were conducted to test the hypothesis that inclusion of 500 phytase units (FTU)/kg of microbial phytase improves the standardized total tract digestibility (STTD) of P in sorghum varieties. The second hypothesis was that the STTD of P, as well as concentrations of digestible energy (DE) and metabolizable energy (ME) in high-lysine sorghum is not different from that of corn and other sources of sorghum.

 

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Effects of dietary leucine concentration on branched-chain amino acid metabolism in growing pigs

Leucine, Val, and Ile are categorized as the branched-chain AA (BCAA) because of the structural similarity of their side chains. All 3 BCAA share the enzymes that are involved in the first 2 steps of their catabolic pathway. The first step is a transamination step catalyzed by BCAA transaminase (BCAT) and producing branched-chain α-keto acids (BCKA). The second step is an irreversible degradation step catalyzed by branched-chain α-keto acid dehydrogenase (BCKDH). In the second step, Leu has been considered a key regulator as its BCKA metabolite (α-keto isocaproate) stimulates activation of the BCKDH complex in the liver. When excess Leu in diets is offered to pigs, degradation of all 3 BCAA may increase because of increased activity of BCAT and BCKDH. Leucine and Trp are both categorized as large neutral AA, and they share a common uptake pathway across the blood-brain barrier. Therefore, it is possible that excessive Leu may result in reduced Trp uptake into the brain due to competition for transporters, resulting in reduced serotonin synthesis.

 

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Basal endogenous loss, standardized total tract digestibility, and retention of calcium in gestating sows changes during gestation, but microbial phytase reduces basal endogenous loss of calcium by gestating sows

Standardized total tract digestibility (STTD) of Ca has been determined for most Ca containing ingredients fed to growing pigs, but the basal endogenous loss of Ca is greater and the STTD of Ca in sows in mid-gestation are less than in growing pigs. As a consequence, if diets for gestating sows are formulated using STTD values determined in growing pigs, the provisions of digestible Ca may be less than anticipated.

The efficacy of phytase to release Ca and P is believed to be influenced by the physiological state of pigs with phytase fed to sows in mid-gestation releasing less Ca and P compared with growing pigs or sows in late-gestation. However, it is not known if values for STTD of Ca or retention of Ca and P that are measured in one period of gestation are representative of the entire gestation period.

Therefore, an experiment was conducted to test the hypothesis that the STTD of Ca from calcium carbonate and the response to microbial phytase on STTD of Ca and apparent total tract digestibility (ATTD) of P in corn-based diets fed to gestating sows are constant throughout the gestating period for sows. The second objective was to test the hypothesis that retention of Ca and P does not change during gestation.

 

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Effects of two direct fed microbials on ileal digestibility of amino acids and total tract digestibility of crude protein and gross energy in diets fed to growing pigs

Direct fed microbials (DFM) are defined as live microorganisms that offer a health benefit for the host when administered in appropriate and regular quantities. Bacillus-based DFM are aerobic, spore-forming bacteria that may enhance the host animal’s immune response and improve growth performance in weanling pigs. Bacillus spp. also produce extracellular enzymes that may enhance digestibility and absorption of nutrients.

An experiment was, therefore, conducted to test the hypothesis that two DFM containing Bacillus strains (provided by Chr. Hansen A/S, Horsholm, Denmark) improve the apparent ileal digestibility (AID) of AA, CP, and GE, the apparent total tract digestibility (ATTD) of CP and GE, and hindgut digestibility of CP and GE when fed to growing pigs.

 

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Comparative digestibility and retention rate of calcium and phosphorus in low- and high-phytate diets fed to gestating sows and growing pigs

Digestibility of Ca and P is most correctly determined as standardized total tract digestibility (STTD). Data for the STTD of P in most feed ingredients have been published, and the STTD of Ca has also been determined in many feed ingredients. However, in practical diet formulation, values for STTD of Ca and P obtained in growing pigs are also applied to sows although there is a lack of comparative data between growing pigs and sows.

Therefore, an experiment was conducted to test the hypothesis that no differences exist between gestating sows and growing pigs for basal endogenous losses, STTD, and retention of Ca and P.

 

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Digestibility of amino acids, fiber, energy, and concentrations of digestible and metabolizable energy in conventional and extruded yellow dent corn, wheat, and sorghum fed to growing pigs

Extrusion of cereal grains may be used to improve nutrient digestibility in cereal grains because addition of heat and pressure in combination with addition of moisture during the extrusion may gelatinize the starch, which results in an increase in starch digestibility. It is also possible that AA and energy digestibility are increased by the extrusion, but data to verify this hypothesis have not been published. Therefore, the objective of these experiments was to test the hypothesis that the ileal digestibility of AA and starch and the apparent total tract digestibility (ATTD) of ADF, NDF, and GE as well as the concentrations of DE and ME in corn, wheat, and sorghum are increased by extrusion.

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Effects of microbial phytase on standardized total tract digestibility of phosphorus in hybrid rye, barley, wheat, corn, and sorghum fed to growing pigs

Until recently, rye has been less suitable for livestock feed than other cereal grains due to the risk of ergot contamination. However, recently developed hybrids are less susceptible to ergot contamination. There is limited information about the nutritional value of hybrid rye when fed to pigs.

In cereal grains, most of the phosphorus is bound to phytic acid, and is not available to pigs unless phytase is present. This is usually achieved by adding supplemental phytase, derived from microbes, to the diets. However, rye contains more intrinsic phytase than other cereal grains, so the phosphorus in rye may be more digestible. The addition of microbial phytase might also have less of an effect on phosphorus digestibility in rye than in other grains because of the high concentrations of intrinsic phytase in rye, but limited information about digestibility of phosphorus in rye has been reported.

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Effects of isoquinoline alkaloids on apparent ileal digestibility of amino acids, acid hydrolyzed ether extract, and starch by young growing pigs fed corn-soybean meal diets

Sangrovit G is a phytogenic feed additive derived from Macleaya cordata composed of isoquinoline alkaloids (IQ), primarily sanguinarine, that are believed to benefit animal performance. Sanguinarine has anti-inflammatory, immuno-modulatory, and antimicrobial effects. As a result, inclusion of IQ in diets for pigs may reduce inflammation in the intestine and thereby increase absorption of essential nutrients.

However, there are no data published for the effects of IQ on digestibility of crude protein, amino acids, starch, and lipids in pigs. Therefore, the objective of the experiment was to test the hypothesis that the apparent ileal digestibility (AID) of crude protein, amino acids, acid hydrolyzed ether extract and starch in corn-soybean meal diets fed to young growing pigs increases as IQ is added to the diet.

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Effects of GraINzyme and AxtraPhy phytases in restoring performance and bone ash in pigs fed low-phosphorus and calcium diets

Last month's newsletter included a research report on research into a novel E. coli phytase expressed in corn, called GraINzyme. Results of that research indicated that adding GraINzyme phytase to diets fed to young growing pigs increased growth performance, digestibility of calcium and phosphorus, and bone mineralization. The comparative effects of GraINzyme and a commercial phytase was not tested in the previous study. Therefore, an experiment was conducted to compare effects of addition of GraINzyme phytase to the commercial phytase AxtraPhy in diets fed to growing pigs.

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Ileal digestibility of amino acids and starch in hybrid rye compared with other cereal grains fed to pigs

Hybrid rye is grown in Europe, Canada, and the United States, and compared with conventional rye, it has increased yields and reduced risk of ergot contamination, making it an interesting ingredient in the feeding of pigs. However, there is limited information about the nutritional value of hybrid rye when fed to pigs. Therefore, the objective of the experiment was to determine the standardized ileal digestibility (SID) of crude protein and amino acids, as well as the apparent ileal digestibility (AID) of starch in hybrid rye compared with barley, wheat, and corn.

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Effect on growth performance and bone mineralization of GraINzyme phytase in diets fed to growing pigs

Most of the phosphorus in corn and other plant-based feed ingredients fed to pigs is bound to phytate. Pigs do not secrete phytase in adequate quantities to liberate significant amounts of phytate-bound phosphorus, meaning that most of the phosphorus in these ingredients is not biologically available. Calcium digestibility is also negatively affected by the presence of phytate in feed ingredients. One way for producers to ensure that pigs' requirements are met is to add supplementary phosphorus to diets. However, this adds to the cost of diets. The excretion of phytate-bound phosphorus also may contribute to algae overgrowth in waterways.

Another approach is to add supplemental phytase to the diets, to allow pigs to better utilize the phosphorus present in the ingredients. Phytases can be obtained from plants, animals, or microorganisms (bacteria, yeasts, and fungi).

GraINzyme is a source of phytase produced by genetically modified corn plants with genes derived from E. coli. In this experiment, the effect on growth performance, apparent total tract digestibility (ATTD) of calcium and phosphorus, and bone mineralization of adding GraINzyme to weanling pig diets was tested.

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The contribution of digestible and metabolizable energy from high fiber dietary ingredients is not affected by inclusion rate in mixed diets fed to growing pigs

Fiber in feed ingredients used in diets for pigs is mainly used for energy, which is synthesized by microbes in the hindgut of the pig and absorbed in the form of short chained fatty acids. To estimate the energy that a pig can obtain in a particular fibrous ingredient, a digestibility experiment is usually conducted and the digestible energy (DE) and the metabolizable energy (ME) in the ingredient is determined. However, it is not known if the obtained DE and ME values are accurate for all inclusion rates of the feed ingredient in diets.

There are two reasons that differing inclusion rates of high fiber ingredients in diets fed to pigs might result in variable DE and ME values. Because energy from dietary fiber is obtained via hindgut fermentation, there may be a saturation point in the fermentation capacity in the hindgut of growing pigs. In addition, increasing dietary fiber increases the passage rate of feed through the digestive tract and thus reduces time for fermentation. However, it is not known if these potential issues affect the DE and ME in fibrous ingredients fed to pigs. An experiment was conducted to determine effects of inclusion rate of four commonly used high fiber dietary ingredients on the concentration of DE and ME by growing pigs.

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Effects of Calmin on energy, calcium, phosphorus, and nitrogen balance and on growth performance of weanling pigs

Calmin is a calcium supplement produced from sea minerals. It also contains 6% magnesium, which may increase calcium absorption. Calmin has been used as a rumen buffer in dairy cows, but limited data are available for pigs. Therefore, two experiments were conducted to test the effect of feeding diets containing Calmin on calcium, phosphorus, and nitrogen balance, energy balance, and growth performance of weanling pigs.

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Effects of different levels of full fat or defatted rice bran on growth performance and carcass quality of pigs

Rice bran is the main coproduct of the production of white rice for human consumption, and is used in livestock diets around the world. Rice bran can be full fat (FFRB), with 14 to 25% fat, or defatted (DFRB), containing 3 to 5% fat.

The type of fat in the diet affects the quality of fat in the pig, because pigs deposit fatty acids in approximately the same proportions as they exist in the diet. A high consumption of unsaturated fat can inhibit the pig's own synthesis of fat, which tends to be more saturated. The amount of unsaturated fatty acids  in fat can be expressed using the iodine value (IV), where high IVs correspond to more unsaturated fat. Increased IV in pig fat can lead to softer bellies, which are less valuable due to reduced shelf life, increased susceptibility to oxidative damage, and reduced belly sliceability.

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Effects of Dakota Gold distillers dried grains with solubles (DDGS) and conventional DDGS on growth performance and carcass quality of pigs fed diets as meal or as pellets

Dakota Gold is a low-oil source of distillers dried grains with solubles (DDGS) produced using a cold-fermentation process. Recent research conducted by the Stein Monogastric Nutrition Laboratory has demonstrated that the standardized ileal digestibility (SID) of amino acids is greater in Dakota Gold than in conventional DDGS, but Dakota Gold contains less metabolizable energy (ME) than conventional DDGS.

An experiment was conducted to determine effects on growth performance and carcass characteristics of feeding Dakota Gold or conventional DDGS to pigs from weaning to market. Because limited information exists about effects of pelleting on growth performance of pigs fed diets that contain DDGS, this research also tested the effects of feeding diets containing either Dakota Gold or conventional DDGS in a meal form or in a pelleted form.

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Digestibility of crude protein and amino acids in Dakota Gold distillers dried grains with solubles (DDGS) fed to pigs is greater than in conventional DDGS

Distillers dried grains with solubles (DDGS) is a co-product of ethanol production. In recent years, companies that produce DDGS have begun to remove some of the corn oil for use in biodiesel production. Conventional DDGS contains 10-12% fat, compared with 6-9% in low-oil DDGS.

Research has shown that adding fat to diets fed to pigs increases the digestibility of amino acids in the diets. However, there is limited information about how reduced oil concentration in DDGS influences the digestibility of protein when fed to pigs. An experiment was conducted to compare the standardized ileal digestibility (SID) of crude protein and amino acids in conventional DDGS and in the low-oil DDGS product Dakota Gold, which is produced using a process that does not involve heating.

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