Amino Acids In Meat Research Articles

Effect of Broussonetia papyrifera L. silage on blood biochemical parameters, growth performance, meat amino acids and fatty acids compositions in beef cattle.

ObjectiveThe study was conducted to investigate the effects of Broussonetia papyrifera L. (B. papyrifera) silage on growth performance, serum biochemical parameters, meat quality, and meat amino acids and fatty acids compositions in beef cattle.MethodsSixty-four male Angus beef cattle were assigned to 4 groups with 4 pens in each group and 4 beef cattle in each pen, and fed with the total mixed ration supplemented with 0%, 5%, 10%, or 15% B. papyrifera silage for 100 days (control group, 5% group, 10% group and 15% group) separately.ResultsBeef cattle had significantly higher final body weight (BW) in 15% group, higher average daily gain (ADG) and dry matter intake (DMI) in 5% group, 10% group and 15% group, and higher feed conversion ratio (FCR) in 10% group and 15% group. Significantly higher blood superoxide dismutase (SOD) concentration was noted in 15% group, higher blood total antioxidant capacity (TAC) in 10% group and 15% group, lower 8-hydroxydeoxyguanosine (8-OHdG) and malondialdehyde (MDA) in 15% group. Meat had lower pH in 15% group, higher Commission International DeI’Eclairage (CIE) L* in 5% group, 10% group, and 15% group, and lower drip loss in 15% group. Greater concentration of meat polyunsaturated fatty acids (PUFA) was observed in 10% group and 15% group, and docosahexaenoic acid (DHA) in 15% group.ConclusionDiet with 15% B. papyrifera silage could improve performance and increase final BW, ADG, DMI, and FCR, enhance the antioxidant functions by decreasing blood 8-OHdG and MDA and increasing blood SOD and TAC, improve the meat quality by lowing pH and drip loss and increasing CIE L*, increase the meat PUFA and DHA concentration. Polyphenols and flavonoids might be the main components responsible for the antioxidant activity and anti-biohydrogenation in the B. papyrifera silage. And B. papyrifera silage could be used as a new feedstuff in beef cattle nutrition.

The carcass traits, carcass nutrient composition, amino acid, fatty acid, and cholesterol contents of local Turkish goose varieties reared in an extensive production system

This study was performed to determine the slaughter and carcass traits, meat color, pH, nutrient composition, fatty acids, amino acids, and cholesterol content of local Turkish goose varieties. In the present study, a total of 80 geese from white, black, gray, and multicolored varieties were reared in an extensive production system at 28 wk of age. Quality analysis was performed on breast and thigh meat, as well as on the skin and abdominal fat of studied geese. Slaughter and carcass weights were significantly higher in the white variety (P < 0.01). Measured abdominal fat was lower in black and gray geese. Furthermore, the color and pH values were significantly different on breast, thigh, and skin among varieties. Additionally, measured breast meat b*, thigh meat L*, and b* values were higher in male geese. Breast meat protein levels were lower in black and gray geese, and also lower in the thigh meat of gray geese. Total breast meat amino acids were lower in white geese, and the amino acid content of thigh meat was lower in multicolored varieties. Moreover, differences in fatty acid composition were found among the studied varieties. However, cholesterol levels did not differ for either sex or variety.

Influence of heat treatment on amino acid composition of snails meat

Amino acids are organic compounds that are the structural component of the protein. That is, protein is the main building material of the tissues of the body. It is needed for muscle mass growth and is indispensable in fat burning – all about amino acids, of which protein is formed. The main source of amino acids are food that is rich in protein. However, based on the content of one or another amino acid proteins contained in food, can be divided into complete and inferior. Complete proteins contain all the essential amino acids. These products include, primarily, products of animal origin: meat, poultry, fish, eggs, dairy products. In order to plant sources of full protein is soybean. Inferior proteins – in their composition there is at least one irreplaceable acid. Accordingly, in their “quality” defective proteins can be very different. The source of defective proteins is mainly products of planting: legumes, cereals, nuts and seeds. The purpose of our work was to determine the content of amino acids in raw and cooked meat of the food species Helix pomatia, Helix aspersa maxima and Helix aspersa muller and to make an analysis on the effect of heat treatment on the amino acid composition of snail meat. This article presents the results of the content of amino acids in meat of food snails using electrophoresis “Capel-105/105M”. Three types of snails have identified the presence and amount of amino acids. In general, the meat of snails contains amino acids – arginine, histidine, serine, alanine, glycine, tyrosine and proline, and irreplaceable – lysine, phenylalanine, leucine + isoleucine, methionine, valine, threonine.

Effects of bypass proteins on growth performance, kidneys and liver functions, rumen fermentation and meat amino acid analysis in male lambs

Effects of bypass proteins on growth performance, kidneys and liver functions, rumen fermentation and meat amino acid analysis in male lambs

Antibiotic-free poultry production based on innovative nutritional programs with the involvement of probiotics

EU banned antibiotic growth promoters (AGP) for farm animals and poultry since 2006 in relation to the problem of drug resistance. This requires alternative products for equally efficient prevention and treatment of certain alimentary poultry diseases. One of the most actual trends is the development of innovative nutritional strategies for poultry providing an effective symbiosis between the host and its intestinal microbiota. The study presented was aimed at the comparative evaluation of productivity, nutritive value of meat, and composition of intestinal microbial populations in broiler chicks fed different diets (corn - soybean meal, wheat - sunflower cake, barley - sunflower cake) supplemented with AGP or a probiotic (cellulolytic and lactic microorganisms). In three trials straight-run Cobb 500 broilers reared from 1 to 36 days of age were fed these diets supplemented with bacitracin from 1 to 29 days of age (control) or probiotic preparation from 1 to 36 days of age (70 birds per dietary treatment in each trial). There were no differences in live bodyweight and carcass yield between the treatments in all three trials. In the two trials with sunflower cake, protein content in breast meat was significantly higher by in birds fed probiotic in compare to birds fed AGP (by 10.0 and 6.8%, p<0.05), while fat content in thigh meat was lower by 12.0% (p<0.05) and 14.1% (p<0.01), respectively. Content of amino acids in meat did not differ. Vitamin content in the poultry meat of the experimental groups was significantly higher compared to control (p<0.001). The resulting concentrations of bacitracin in meat in control treatments (no more than 0.02 U/g) did not exceed local legislative limitations. The substitution of the probiotic for AGP beneficially affected the composition of bacterial populations in the duodenum and cecae determined using T-RFLP analysis. It was concluded that the supplementation of diets with probiotic allows to produce antibiotic-free broiler meat without detrimental effects on the productive performance.

In the elderly, meat protein assimilation from rare meat is lower than that from meat that is well done

Background: Meat cooking conditions in in vitro and in vivo models have been shown to influence the rate of protein digestion, which is known to affect postprandial protein metabolism in the elderly.Objective: The present study was conducted to demonstrate the effect of cooking conditions on meat protein assimilation in the elderly. We used a single-meal protocol to assess the meat protein absorption rate and estimate postprandial meat protein utilization in elderly subjects.Design: The study recruited 10 elderly volunteers aged 70-82 y. Each received, on 2 separate occasions, a test meal exclusively composed of intrinsically 15N-labeled bovine meat (30 g protein), cooked at 55°C for 5 min [rare meat (RM)] or at 90°C for 30 min [fully cooked meat (FCM)], and minced. Whole-body fluxes of leucine, before and after the meal, were determined with the use of a [1-13C]leucine intravenous infusion. Meat protein absorption was recorded with the use of 15N enrichment of amino acids.Results: Postprandial time course observations showed a lower concentration in the plasma of indispensable amino acids (P < 0.01), a lower entry rate of meat leucine in the plasma (P < 0.01), and a lower contribution of meat nitrogen to plasma amino acid nitrogen (P < 0.001), evidencing lower peripheral bioavailability of meat amino acids with RM than with FCM. This was associated with decreased postprandial whole-body protein synthesis with RM than with FCM (40% compared with 56% of leucine intake, respectively; P < 0.01).Conclusions: Whereas meat cooking conditions have little effect on postprandial protein utilization in young adults, the present work showed that the bioavailability and assimilation of meat amino acids in the elderly is lower when meat is poorly cooked. In view to preventing sarcopenia, elderly subjects should be advised to favor the consumption of well-cooked meat. This trial was registered at clinicaltrials.gov as NCT02157805.

КІЛЬКІСНИЙ І ЯКІСНИЙ АМІНОКИСЛОТНИЙ СКЛАД М’ЯСА КУРЧАТ–БРОЙЛЕРІВ ЗА ЗБАГАЧЕННЯ РАЦІОНУ НАНОМІКРОЕЛЕМЕНТНОЮ КОРМОВОЮ ДОБАВКОЮ «МІКРОСТИМУЛІН»

The work analyzes qualitative and quantitative amino acid composition of broiler meat for diet enrichment nanotracelement feed additive «Mikrostymulin». It was founded that poultry muscle in control and experimental groups contain such essential amino acids, as threonine, valine, isoleucine, leucine, phenylalanine, lysine, methionine, and tryptophan tsystin. Research the quality of the essential amino–acids showed the presence of aspartic acid, serine, glycine, tyrosine, alanine, glutamic acid, proline, histidine, arginine and oxyproline.It was established that the use of «Mikrostymulin» increases the content of amino acids in meat of broiler chickens. In muscles of broiler chickens in the 1st research group, have beenadded «Mikrostymulin» in a dose of 1 ml/dm³ of water, the amount of essential amino acids and replacement tends to increase at chest and hip muscles, compared with the contro group.. Obviously, this can be explained by improved assimilation of food and stimulating the synthesis of amino acids under the influence of the components of the feed additive. In chickensof the 2nd research group,they received «Mikrostymulin» at a dose of 10 ml/dm³ water, it was registered a tendency to increase essential amino acids in the pectoral muscles, but in the femoral – it was tendency to decrease. In chickens of the 3 rd research group, they received«Mikrostymulin» at a dose of 20 ml/dm³ water, it was registered a tendency to reduce the amount of essential amino acids in the chest and thigh muscles. Number of essential amino–acids in chicken pectoral muscle in the 2 nd experimental group also increased slightly, and in the3 rd – reduced slightly, but in the femoral muscles they decreased slightly in the 2 nd and 3 rd experimental groups compared to control group.It is proved that the use of nanotracelement feed additive «Mikrostymulin» in a dose of 1 ml / dm³ of water improves the quality and increases the biological value of meat.

Comparative characteristics of amino acid composition of meat of crossbred and purebred young stock rabbits

The contents of the essential and nonessential amino acids in meat of the crossbred (White Giant × Soviet Chinchilla × Californian) and purebred (White Giant and Soviet Chinchilla) young stock rabbits are analyzed. The age-associated tendencies to both increasing and decreasing the essential amino acid contents have been ascertained in the crossbred rabbits and the purebred animals, respectively. The highest increase in the value for meat protein quality was registered in the crossbred young stock animals (20.7%) aged 77 to 90 days, while the lowest rise for the item was recorded in the White Giant peers (1.5%). The essential amino acid contents in the boneless carcasses of the crossbred young stock animals compared to the White Giant and the Soviet Chinchilla young-stock rabbits at the age of 77 days were 5.9 g or 6.5% and 9.3 g or 10.6% higher, respectively; with respect to the 90-day-old animals, the values comprised 9.9 g or 9.2% and 18.3 g or 18.5%, respectively.

Effects of Graded Levels of Chromium Methionine on Performance, Carcass Traits, Meat Quality, Fatty Acid Profiles of Fat, Tissue Chromium Concentrations, and Antioxidant Status in Growing-Finishing Pigs.

A 97-day feeding trial was conducted to investigate the effects of dietary chromium methionine (CrMet) on performance, carcass traits, meat quality, fatty acid profiles of fat, tissue chromium concentrations, and antioxidant status in growing-finishing pigs. A total of 180 crossbred pigs with a mean initial body weight (BW) 30.18 ± 0.28kg were allotted to 5 treatments with 6 replicates per treatment and 6 pigs per pen in a randomized complete block design based on BW and sex. Treatments were added with 0 (control), 100, 200, 400, and 800μg/kg chromium as CrMet. Blood samples were obtained from the anterior vena cava on days 97. Carcass characteristics, pork quality, and tissue chromium concentration data were collected from one pig per pen. The results indicated that supplemental CrMet did not significantly affect growth performance, carcass traits, or meat amino acid profiles. Chromium at 100, 400, and 800μg/kg decreased drip loss but increased shear force (P < 0.05). Pigs fed 100 or 400μg/kg had a higher 24-h pH than the control (P < 0.05). While meat color, muscle moisture, crude protein, or crude fat were not affected by CrMet. Supplemental 800μg/kg chromium reduced C18:0 levels in belly fat (P < 0.05), and chromium supplementation increased cis-9, trans 11-conjugated linoleic acid levels linearly (P < 0.05). Dietary CrMet supplementation increased serum, kidney, and muscle chromium contents (P < 0.05) but did not affect liver chromium contents. Besides, tissue chromium concentrations were increased linearly with increased chromium dosage (P < 0.05). Chromium at 400μg/kg increased serum glutathione peroxidase activities (P < 0.05), and chromium at 800μg/kg decreased serum total antioxidant capacity levels (P < 0.05). Nevertheless, liver and kidney antioxidant status were not significantly affected by CrMet. These results indicated that dietary supplementation CrMet did not significantly influence growth and carcass traits, but improved meat quality at the expense of tenderness. Therefore, the long-term exposure to 800μg/kg chromium affected fatty acid compositions and reduced serum antioxidant capacity.

Use of markers to determine the ileal digestibility of amino acids for swine

Many markers can be used in digestibility assays for swine, but needs to be evaluated before its use. An assay was carried out with the objective of measuring the coefficients of ileal apparent (CIAD) and standardized digestibility (CISD) of amino acids in meat and bone meal for swine using different markers. Eight crossbred barrows were equipped with T-cannulas in the distal ileum. Four animals received a free protein diet and another four received a diet containing meat and bone meal as the only protein source in the diet. The treatments consisted in evaluating the chromic oxide, acid-insoluble ash naturally occurring in the diet, cellulose and lignin as markers to determine the apparent and standardized digestibility of the amino acids contained in the meat and bone meal. All data were submitted to analysis of variance and means were compared using the Tukey test, with a significance of 5%. The CIAD, obtained using chromic oxide as external marker, were lower (P&lt;0.05) than those obtained when acid insoluble ash, lignin and cellulose were used as markers, observing differences for all the amino acids evaluated. Similarly, the CISD from all the studied amino acids were lower (P&lt;0.05) when the chromic oxide was used for determining the indigestibility factor. It is concluded that chromic oxide used as a external marker, to determine the coefficients of apparent and standardized ileal digestibility of the amino acids of the meat and bone meal, is most appropriate than the acid insoluble ash naturally occurring in diets, lignin and cellulose.

닭고기의 성분조성에 미치는 감귤껍질 급여의 영향

본 연구는 감귤껍질 첨가 사료를 급여한 닭고기의 성분조성을 검토하기 위하여 실시하였다. 닭고기는 초기, 중기 및 후기 모두 감귤껍질을 첨가하지 않은 육계용 배합사료로 사육한 CP-0, 그리고 초기(1<TEX>${\sim}$</TEX>9일), 중기(10<TEX>${\sim}$</TEX>24일) 및 후기(25<TEX>${\sim}$</TEX>36일) 사료에 감귤껍질을 각각 1.0%, 1.5% 및 2.0%를 첨가하여 급여한 CP-1으로 구분하였다. 일반성분 및 열량은 감귤껍질 급여의 영향이 없었으나 콜레스테롤 함량은 CP-0 보다 CP-1이 유의하게 낮았다 (p<0.05). K, P 및 ca는 CP-1이 CP-0보다 함량이 높았으나 Na 및 Mg는 CP-0 및 CP-1 사이에 유의한 차이가 없었다. 비타민 A, xanthophyll, <TEX>${\beta}$</TEX>-carotene, hesperidin 및 naringin은 감귤껍질 급여의 영향이 없었지만 비타민 <TEX>$B_1$</TEX> 및 <TEX>$B_2$</TEX>는 감귤껍질을 급여한 닭고기가 유의하게 높았다(p<0.05). 아미노산 조성은 CP-0 및 CP-1 사이에 유의한 차이가 없었으며, 대부분의 유리아미노산도 유의한 차이가 없었으나 유리아미노산 중 L-glutamic acid는 CP-0가 CP-1보다 높았고, DL-<TEX>${\beta}$</TEX>-amino isobutyric acid는 CP-1이 더 높았다(p<0.05). 그리고 지방산 조성은 CP-0와 CP-1 사이에 유의한 차이가 없었다. In this study, the effects of feeding citrus peel on the nutritional composition of chicken meat were investigated. The samples consisted of chicken meats provided with only feed for laying hens without citrus peel (CP-0), and chicken meats fed with 1.0%, 1.5% and 2.0% citrus peel during the starter (initial period feed; 1<TEX>${\sim}$</TEX>9th day), the grower (middle period feed; 10<TEX>${\sim}$</TEX>24th day), and the finisher (latter period feed; 25<TEX>${\sim}$</TEX>36th day), respectively. There was no significant difference between CP-0 and CP-1 regardless of feeding citrus peel in terms of chicken's moisture, protein, fat, ash or caloric content. The cholesterol content was significantly lower in the CP-1 chicken meats than in the CP-0 chicken meats (p<0.05). The K P and Ca contents were significantly higher in the CP-1 chicken meats than in the CP-0 chicken meats (p<0.05), but there were no significant differences between CP-0 and CP-1, regardless of feeding citrus peet in terms of chicken meat's Na and Mg. There were no significant differences between CP-o and CP-1 regardless of feeding citrus peet in terms of chicken meat's vitamin A, xanthophyll, <TEX>${\beta}$</TEX>-carotene, hesperidin or naringin, but vitamins <TEX>$B_1$</TEX> and <TEX>$B_2$</TEX> were significantly higher in the CP-1 chicken meats than in the CP-0 chicken meats (p<0.05). There were no significant differences between CP-0 and CP-1 regardless of feeding citrus peet in terms of chicken meat's amino acid composition - most of free amino acids and fatty acid composition - but L-glutamic acid was significantly higher in the CP-0 chicken meats than in the CP-1 chicken meats, and the DL-<TEX>${\beta}$</TEX>-amino isobutyric acid was significantly higher in the CP-1 chicken meats than in the CP-0 chicken meats (p<0.05).

Effect of Several Sugars on Consumer Perception of Cured Sheepmeat

This article reports the perception of cooked, nitrite-cured sheepmeat sausage that included 1.5% glucose, sucrose, xylose, or no sugar addition. The 4 sugar treatments were dry-cooked, vacuum packed, and stored chilled, and were hedonically assessed after 0, 1, and 2 mo. Consumers were advised that they could be eating any 1 of beef, chicken, lamb, pork, or turkey, in a salted cured preparation. Three-way analysis of variance (ANOVA) showed that liking of appearance, color, and texture were unaffected by sugar treatment, whereas liking of aroma, flavor, sweetness, and overall liking were markedly and significantly increased by xylose. Storage time as a factor had minimal effects on liking. In contrast, all attributes were liked more by male consumers (57%, P < 0.001). When asked to identify the meat species, lamb was correctly identified 50% of the time. With xylose, the observed frequency of lamb's misidentification as beef increased by 50% above the expected Chi-square frequency. This was largely at the expense of observed lamb selection frequency, which was 18% below expectation. When data were segregated by gender, the misidentification remained significant for males (P = 0.002), but was not significant for females (P = 0.32). The misidentification of beef for lamb may be due to the generation of Strecker aldehydes in the Maillard reaction between xylose and meat amino acids, which were shown to be greatly increased in the headspace above xylose-treated sausage. The restriction of significant misidentification to males is less easy to explain but may be associated with the possible greater sensitivity of females to volatile fatty acids, which are components of sweat.

Comparison of the Ileal Digestibility of Amino Acids in Meat and Bone Meal for Broiler Chickens and Growing Rats

The apparent ileal amino acid digestibility in 15 meat and bone samples was compared in growing broiler chickens and growing laboratory rat. The animals were given a diet containing meat and bone meal as the sole source of protein. All diets contained chromic oxide as the indigestible marker to calculate the digestibility estimates. Comparison of digestibility data shows that, for all dispensable amino acids, apparent ileal amino acid digestibility was similar (p>0.05) between broiler chicken and the growing rat. However, the ileal amino acid digestibility was similar (p>0.05) between the two species for only four (histidine, methionine, threonine and valine) of the nine indispensable amino acids. Significant differences (p<0.01 to 0.05) were observed between the estimates in the broiler chicken and the rat for arginine, leucine, lysine, phenylalanine and cystine. Differences approaching statistical significance were observed for isoleucine (p=0.06) and tyrosine (p=0.10). For the amino acids, which differed between the species, the values obtained for broilers were consistently 4 to 7 percentage units lower than those in the rats. The exception was cystine, with digestibility in broilers being 17 percentage units lower than in the rat. The present data do not support the use of the growing rat as a model for growing chickens in the determination of ileal amino acid digestibility.

Food and cancer

Food is an important factor in determining cancer incidence in many countries and regions. Food components relevant to cancer development can be divided into macro- and microcomponents. The former tends to act indirectly. The latter usually has a clearly defined action, for example as genotoxic agents. Food can have both positive (carcinogenic) and negative (preventive) effects. Total calory intake appears to have a strong positive influence on cancer incidence. Food typical of advanced nations including fat-rich food is associated with increases in breast, colon and prostate cancers. Vegetables rich in antioxidants and fibers tend to reduce cancer incidence. Carcinogenic plant alkaloids, myctoxins and other food contaminants frequently enter our bodies. Heat-cooking generates genotoxicants, including aromatic hydrocarbons (via combustion) and heterocyclic amines (HCAs) through reactions involving creatin(in)e, sugar and amino acids in meat. HCAs are relatively newcomers as food genotoxicants and can produce breast, colon and prostate cancers in rodents. Some epidemiological investigations positively correlate HCA intake and cancer incidence. HCAs can produce other toxicological effects including salivary gland atrophy and myocardial degeneration. Improved food, better life styles and developments in the functional food industry are all crucila to cancer prevention.

Apparent ileal digestibility of amino acids in protein feedstuffs and diet formulation based on total vs digestible lysine for poultry

A digestibility experiment was carried out with 140 Ross-broiler chickens (age 24 days) to determine coefficient of ileal apparent digestibility (CIAD) of amino acids in meat and bone meal (MBM), full-fat soyabeans (FFSs), soyabean cake and meal, full-fat rapeseeds, and rapeseed cake and meal. The birds were fed semi-purified diets which contained protein feedstuffs as a sole protein source and chromium mordanted straw as an indigestible marker. The CIAD of nutrients were assessed using the slaughter technique. A 37-day growth experiment was carried out with 2880 Ross-broiler chickens to compare feed formulation systems based on apparent ileal digestible or total lysine content. Three barley based diets were formulated to be similar in total lysine content (9.5 g/kg feed). Diet 1 contained soyabean meal (SBM) (280 g/kg DM), Diet 2 SBM (180 g/kg DM) and rapeseed meal (RSM) (171 g/kg DM) and Diet 3 a combination of SBM (78 g/kg DM), RSM (172 g/kg DM) and MBM (87 g/kg DM). The composition of Diets 4 and 5 was similar to that of diets 3 and 4, respectively, except that they were supplemented with l-lysine–HCl to obtain a similar apparent ileal digestible lysine content as in Diet 1 (7.9 g/kg feed). The total lysine content of Diets 4 and 5 was 10 g/kg feed. Furthermore, Diet 1 was supplemented with l-lysine–HCl to obtain Diet 6, in which the total and apparent ileal lysine contents were 10 and 8.5 g/kg feed, respectively. CIAD of lysine, methionine, threonine and cystine were respectively 0.60, 0.66, 0.48 and 0.34 for MBM; respectively 0.81, 0.75, 0.68 and 0.67 for FFSs; respectively 0.86, 0.86, 0.76 and 0.62 for soyabean cake; respectively 0.85, 0.84, 0.74 and 0.63 for SBM; respectively 0.59, 0.59, 0.43 and 0.53 for full-fat rapeseeds; respectively 0.68, 0.81, 0.64 and 0.53 for rapeseed cake; and respectively 0.63, 0.75, 0.54 and 0.43 for RSM. Final weight and growth rate were highest when digestible lysine based feed formulation was used compared to that based on total lysine ( P<0.001). The increase in final weight was largest for diet containing MBM and formulated based on digestible lysine ( P<0.001). In addition, the proportion of breast muscle of total live-weight and weight of breast muscle increased ( P<0.05) in animals fed diets formulated on the basis of digestible compared to total lysine. However, diet formulation based on digestible lysine impaired feed conversion ratio compared to that of total lysine for birds fed SBM as the sole source of supplementary protein compared to diets containing rapeseed or MBM ( P<0.01). Growth rate and final weight were higher in birds fed diets containing SBM alone compared to those also containing RSM and MBM ( P<0.001). In addition, the effect of diet formulation based on digestible lysine on performance results of broilers was more obvious in males than females ( P<0.05). The results indicated that formulation of diets based on a digestible lysine was better than that based on total lysine when diets contained protein sources of low amino acid digestibility such as meat and bone and RSMs.

Nutrition and dietary carcinogens.

Three major factors for human carcinogenesis are (i) cigarette smoking, (ii) infection and inflammation and (iii) nutrition and dietary factors. Nutrition and dietary factors include two categories, namely genotoxic agents and constituents including tumor promotion-associated phenomena. This article first describes the genotoxic agents as microcomponents. These are mutagens/carcinogens in cooked food, fungal products, plant and mushroom substance, and nitrite-related materials, polycyclic aromatic hydrocarbons and oxidative agents. Emphasis has been given to heterocyclic amines (HCAs) to which humans are continuously exposed in an ordinary lifestyle. HCAs in food are mainly produced from creatin(in)e, sugar and from amino acids in meat (upon heating). They are imidazoquinoline and imidazoquinoxaline derivatives and phenylimidazopyridine. HCAs are pluripotent in producing cancers in various organs including breast, colon and prostate. Discussion is also given to plant flavonoids which are mutagenic but not carcinogenic. As a macrocomponent, overintake of total calories, fat and sodium chloride is discussed from the viewpoint of the increase of genetic alterations in tissues and of tumor promotion-associated issues. Studies of nutrition and dietary condition will eventually lead us to cancer prevention, namely delay of onset of cancer to the late phase of human life, which is called 'natural-end cancer' (Tenju-gann).

Bioavailability of the digestible lysine and total sulfur amino acids in meat and bone meals varying in protein quality

Experiments were conducted to determine whether the digestible Lys, Met, and TSAA in a high and low quality meat and bone meal (MBM) were totally bioavailable for protein synthesis in chicks. True digestibility of amino acids (AA) in the two MBM was determined by the precision-fed cecectomized rooster assay. Bioavailability of the digestible AA was then assessed in three slope-ratio chick growth assays using Lys-, Met-, or TSAA-deficient crystalline AA basal diets that were supplemented with varying levels of the test AA, high or low quality MBM, or AA mixtures simulating the mean digestible AA composition of the high and low quality MBM. Response parameters were weight gain, feed efficiency, body N gain, and body Lys gain in the Lys assay and weight gain and feed efficiency in the Met and TSAA assays. Bioavailability values for the digestible Lys, Met, and TSAA in the MBM and AA mixtures simulating MBM varied depending on response parameter, with values based on feed efficiency generally being highest. No consistent differences in bioavailability of the digestible AA were observed between the two MBM when all AA were considered; however, the bioavailability of the digestible Lys in the low quality MBM was lower than that in the high quality MBM for two of four performance criteria. When considering all response parameters and the AA mixture results, bioavailability of the digestible Lys and Met in the two MBM was generally 90% or greater, whereas bioavailability of the digestible TSAA was only 80% or less. The results of this study indicated that essentially all of the digestible Lys and Met in MBM were bioavailable for protein synthesis and metabolism but suggested that a significant amount of the TSAA, particularly Cys, was not bioavailable.

Limiting amino acids in meat and bone and poultry by-product meals.

In situ, digestion, and growth studies were conducted to evaluate four meat and bone meals and six poultry by-product meals as sources of escape protein and to predict the first-limiting amino acid for growing calves. Escape protein values, determined by 12-h in situ incubation, ranged from 41.7 to 51.0% of CP for meat and bone meals; poultry by-product meals ranged from 32.0 to 39.8%. True protein digestion in the gastrointestinal tract of lambs differed among protein sources (P < .05), ranging from 79 to 95%. In each of three growth trials, 60 steers (258 +/- 24, 241 +/- 23, and 230 +/- 16 kg for Trials 1, 2, and 3, respectively) were supplemented with 4 of the 10 protein sources along with a urea supplement. Protein sources were fed at 30, 40, 50, and 60% of the supplemental CP, with urea supplying the remainder. Protein efficiency differed among treatments ( P < .10), ranging from .61 to 1.55. Amino acid composition was determined for each protein source, and the individual metabolizable amino acids were regressed on the protein efficiency values. Escape protein values were correlated (R2 = .75) with protein efficiency but had a negative slope. Metabolizable methionine was the only amino acid moderately correlated (R2 = .40, slope = 1.9) to protein efficiency, whereas other amino acids either correlated poorly or had negative slopes. These data indicate that the protein value of meat and bone meal and poultry by-product meal is limited by the amount of metabolizable methionine they contain.

True ileal digestibility of amino acids in meat and bone meal for the growing pig—application of a routine rat digestibility assay

Eight samples of meat and bone meal were evaluated for their nutrient compositions and true digestible amino acid contents using a routine rat ileal digestibility assay. The rat assay has been validated for application to the growing pig. Ileal endogenous amino acid excretion, used for the correction of apparent digestibility values to true estimates, was determined for rats given a protein-free diet, or an enzymically hydrolysed casein (EHC) based diet and after ultrafiltration of the ileal digesta. The meat and bone meals varied in their nutrient composition and in the true ileal digestibility of protein and amino acids. The gross contents (g per 100 g air-dry weight) for crude protein, ash, lysine and methionine + cystine ranged from 47.8 to 59.3, 19.1–31.1, 2.45–3.89 and 1.25–1.93, respectively. Mean ileal endogenous nitrogen (N) and amino acid flows were significantly higher with the EHC versus the protein-free method, except for histidine and glycine. The mean ileal endogenous N flows were 1843 μg and 1124 μg g −1 food dry matter intake for rats fed the EHC and protein-free diets, respectively. The true nitrogen and amino acid digestibility coefficients based on endogenous flows determined by the EHC method were markedly higher than those determined using the traditional protein-free method. The true ileal N and lysine digestibility coefficients based on the respective endogenous flows for rats fed the EHC diet ranged from 62.7 to 88.9% and 66.4–92.3%, respectively. Values determined with endogenous flows for rats fed the protein-free diet ranged from 59.0 to 85.2% for N, and 63.2–88.9% for lysine. The variable ileal digestible N and amino acid contents of meat and bone meal emphasise the limitation of tabulated compositional values and the need for a routine relatively inexpensive digestibility assay.

Carcinogenic factors in food with relevance to colon cancer development

The diet contains various mutagens and carcinogens that can be classified into three groups: naturally occurring chemicals, synthetic compounds and compounds produced by cooking. The first group includes mycotoxins and plant alkaloids while the second is exemplified by flod additives and pesticides. The third includes polycyclic aromatic hydrocarbons and heterocyclic amines (HCAs). HCAs are mutagenic to microbes and eukaryotes and their precursors are creatine or creatinine, sugars, and amino acids in meat and fish. Among 10 HCAs so far examined for carcinogenicity in rodents, 2-amino-6-methyldipyrido[1,2- a:3′- d]imidazole (Glu-P-1), 2-aminodipyrido[1,2- a:3′,2′- d]imidazole (Glu-P-2), 2-amino-3-methylimidazo[4,5- f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5- f]quinoline (MeIQ) and 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine (PhIP) induced colon cancer in rats. PhIP is an especially interesting compound inducing colon tumors specifically in male F344 rats and only very rarely in females, which develop mammary carcinomas at high frequency instead. Since induced DNA adduct levels, determined by the 32P-postlabeling method, were found to be almost the same in male and female F344 rats adduct formation in itself is not directly responsible for carcinogenesis. We established, however, that PhIP causes increased cell proliferation in colon mucosa but not in the non-target liver or kidney of male rats. Induction of cell proliferation is therefore possibly an additional important factor determining carcinogenic organ specificity. In terms of molecular alteration ras family gene mutations are very rare and no mutations are evident in the p53 gene in colon tumors induced by HCAs. Their development due to HCAs can thus be considered an appropriate experimental model for human colon tumors in which ras or p53 gene activation is not involved. Since HCAs are genotoxic compounds, a causal role in some stage of human colon carcinogenesis is plausible. Exposure to HCAs should accordingly be avoided as far as possible.