Proteic-anabolic capacity in rats — influence of the quality and quantity of dietary protein

The effect of quality (casein + 5% DL-methionine, normal or heated at 180 °C for 20 min) and quantity (4%, 6%. 10%, 15% and 20%) of dietary protein on food intake, weight increase and nitrogen retention, has been studied in both sexes weaning Nestle rats. Our results show that food intake, when expressed as g dry matter/100 g body weight and day, is not dependent on the quality and quantity of dietary protein. Weight increase goes up at a 10% dietary protein level. At higher protein levels (15% and 20%) values are only maintained. Protein quality do not cause any difference. Nitrogen retention goes up on increasing dietary protein level, with a maximum at 10% casein-methionine and 15% heated protein, being retention heated casein-methionine significantly lower. At a higher protein level, the maximal anabolic capacity for protein is maintained. Maximum Protein Productive Value (PPV) is obtained from diets containing 10% protein level (normal or heated). There is a significant decrease at higher protein levels (15% and 20%). The PPV of heated casein-methionine is lower than PPV of normal one at 6%, 10%. 15% and 20% protein levels. The results state that in our assays, in spite of the good quality of heated casein-methionine, its metabolic efficiency is below non heated protein values even when protein contribution is increased. We can assume that protein quantity is not a balancing factor for protein quality.     

Effect of rancidity of Lupinus albus protein-concentrate-based diets on food intake and growth of Wistar rats

The organoleptic properties of a diet are influenced by technological processes and have to be taken into account in food intake studies. The authors studied the food intake suppression associated with rancidity occurring during the storage of diets based on casein or heated or lyophilised lupin protein concentrates, and with or without ascorbic acid supplementation in five groups of 10 weanling Wistar rats for 21 or 26 days. After 15 days of storage, the unsaturated fatty acids were oxidised in heated lupin-protein-based diet without ascorbic acid. Compared to casein, food intake was decreased slightly during the first 10, 16 or 20 days for, respectively, heated lupin protein diet without ascorbic acid, heated lupin protein diet with ascorbic acid, and lyophilised lupin protein diet with or without ascorbic acid. After these periods, food intake decreased strongly. Body weight gain variations did not exactly follow food intake variations. The storage at 20°C could induce first an accumulation of free radicals, which were not detectable in measurement of fatty acids but perceived by rats, and then a fast oxidation of unsaturated fatty acids that increased rancid smell, modified nutritional quality and caused a dramatic decrease of rat food intake. Supplementing ascorbic acid into the diet could diminish the formation of free radicals at the beginning of storage, and consequently could delay food intake decrease. © 1997 SCI.     

Malnutrition and dietary protein: evidence from China and from international comparisons

Malnutrition, as measured by anthropometric status, is a powerful risk factor for illness and elevated death rates throughout life. Understanding the relative importance of disease, dietary quantity, and dietary quality in causing malnutrition is therefore of major importance in the design of public policy. This paper contributes to the understanding of the relative importance of quantity and quality of diet by utilizing aggregate data to complement previously reported individual-level studies. Three compilations of anthropometric data--one involving subjects from 13 provinces in China, another involving subjects from 64 counties in China, and a third involving 41 populations in 40 countries--are used to examine the relative importance for human growth of inadequacies of dietary energy and protein. The analysis involves regressing average adult heights and weights against estimates of average energy and protein availability (by province, county, or country) and per capita incomes. We use protein availability in part as a marker for overall quality of the diet, while recognizing that protein is far from perfectly correlated with dietary fat or micronutrient availability. The paper discusses issues of both data quality and statistical methodology, and points to relevant resulting caveats to our conclusions. Subject to these limitations, all three analyses suggest that, at the levels of dietary intake in these populations, lower protein intake is related to growth failure whereas lower levels of energy availability are not. The protein effect appears stronger for males than for females.     

Response of dairy cows in early lactation to sodium hydroxide-treated soybean meal

To determine effects of protein and rumen degradability in rations for early lactation cows, four diets (44:56 roughage:concentrate) were formulated to contain 15 or 17.5% CP and supplemental protein from untreated or NaOH-treated soybean meal. Diets were allocated to 34 multiparous Holstein cows from d 22 to 91 of lactation. Treatment means adjusted by covariance using data from d 10 to 21 for average daily milk (kg), milk fat (%), milk protein (%), and SCM (kg) were: 15% untreated 32.9, 3.54, 3.16, and 31.3; 15% NaOH-treated 31.1, 3.59, 3.08, and 29.6; 17.5% untreated 32.2, 3.70, 3.30, and 31.2; and 17.5% NaOH-treated 32.6, 3.58, 3.17, and 30.8. Increasing dietary protein percent raised milk protein percent but not protein yield or yield of other milk components, milk yield, SCM yield, or DM intake. Protein source had no effect on production or feed intake. Decreasing dietary protein percentage and use of NaOH-treated soybean meal reduced rumen ammonia. Degradation of protein in feeds was determined in four rumen fistulated lactating cows. Sodium hydroxide treatment of soybean meal reduced protein degradation in situ.     

Nutritional requirements of the aged

The age of the population continues to increase. At the turn of the century, 4% (about 3.1 million people) were 65 years of age or older. Today the percentage has increased to 12%, or 27.4 million people, and the prediction for the 21st century may increase to 17 to 20%. It should be noted that the number of individuals 85 years of age and older, as well as those over the age of 100, is increasing rapidly. The nutritional problems of the elderly are related to physiological decline, to low economic status and limited food consumption, and to a multitude of disease processes and the therapeutic regimens prescribed to cure or treat those illnesses. Examined as a group, the elderly at first appear to be less uniform in their health status than younger members of the population. However, only 10% of the elderly population contributes to the disproportionate (30%) expenditure of health care services. A majority of the elderly are normal, healthy individuals. Yet, with each decade of life the percentage of the elderly population needing additional care increases. The national nutritional surveys (National Food Consumption Survey and the National Health and Nutrition Examination Surveys, I and II) used entirely different methodologies, but reported very similar findings. The mean intake of this population was actually quite good, revealing low intakes of calcium and iron in the elderly female population. However, the standard deviation of the intake data strongly suggests a major portion of the population is at nutritional risk. For more than 30% of the population, nutrient intakes below two thirds of the recommended dietary allowances (RDA) occurred for calories, calcium, and vitamin A, while for more than 20% of the population, iron and vitamin C were at risk. Although the data evaluating the effects of age on the nutritional requirements of the elderly are limited, careful interpretation of the existing assessment and intervention efforts can provide some basic guidelines. Generalities about calorie intake must be avoided, and emphasis must be placed on calorie needs. Enhanced activity should be encouraged. Protein intake for the majority of elderly exceeds the RDA, but with increased age a greater amount of high quality protein is needed to maintain nitrogen balance. The group at greatest risk is the poor elderly who may not be able to afford enough high quality protein. Increased consumption of complex carbohydrates serves several functions including decreased caloric density and enhanced nutrient intake. Decreasing total dietary fat decreases caloric intake and indirectly decreases dietary cholesterol.(ABSTRACT TRUNCATED AT 400 WORDS)     

Urea-N recycling in lactating dairy cows fed diets with 2 different levels of dietary crude protein and starch with or without monensin

Rumensin (monensin; Elanco Animal Health, Greenfield, IN) has been shown to reduce ammonia production and microbial populations in vitro; thus, it would be assumed to reduce ruminal ammonia production and subsequent urea production and consequently affect urea recycling. The objective of this experiment was to determine the effects of 2 levels of dietary crude protein (CP) and 2 levels of starch, with and without Rumensin on urea-N recycling in lactating dairy cattle. Twelve lactating Holstein dairy cows (107 ± 21 d in milk, 647 kg ± 37 kg of body weight) were fed diets characterized as having high (16.7%) or low (15.3%) CP with or without Rumensin, while dietary starch levels (23 vs. 29%) were varied between 2 feeding periods with at least 7 d of adaptation between measurements. Cows assigned to high or low protein and to Rumensin or no Rumensin remained on those treatments to avoid carryover effects. The diets consisted of approximately 40% corn silage, 20% alfalfa hay, and 40% concentrate mix specific to the treatment diets, with 0.5 kg of wheat straw added to the high starch diets to enhance effective fiber intake. The diets were formulated using Cornell Net Carbohydrate and Protein System (version 6.1), and the low-protein diets were formulated to be deficient for rumen ammonia to create conditions that should enhance the demand for urea recycling. The high-protein diets were formulated to be positive for both rumen ammonia and metabolizable protein. Rumen fluid, urine, feces, and milk samples were collected before and after a 72-h continuous jugular infusion of ¹⁵N¹⁵N-urea. Total urine and feces were collected during the urea infusions for N balance measurements. Milk yield and dry matter intake were improved in cows fed the higher level of dietary CP and by Rumensin. Ruminal ammonia and milk and plasma urea nitrogen concentrations corresponded to dietary CP concentration. As has been shown in vitro, Rumensin reduced rumen ammonia concentration by approximately 23% but did not affect urea entry rate or gastrointestinal entry rate. Urea entry rate averaged approximately 57% of total N intake for cattle with and without Rumensin, and gastrointestinal rate was similar at 43 and 42% of N intake for cattle fed and not fed Rumensin, respectively. The cattle fed the high-protein diet had a 25% increase in urea entry rate and no effect of starch level was observed for any recycling parameters. Contrary to our hypothesis, Rumensin did not alter urea production and recycling.     

Effects of increasing dietary protein on nutrient utilization in heifers

Four prepubertal Holstein heifers, average age 146.0 +/- 3.6 d and 152.8 +/- 8.6 kg of body weight (BW), fitted with rumen cannulae were used to evaluate increasing levels of dietary protein with a constant metabolizable energy intake on rumen ammonia N concentrations, N balance, total tract apparent digestibility, and urinary excretion of purine derivatives in a 4 x 4 Latin square design with 20 d periods. Heifers were fed dietary crude protein levels (CP) of 11.9, 16.7, 18.1, and 20.1% CP with similar amounts of metabolizable energy (ME) (2.6 Mcal per kg of dry matter) at 2.0% BW as dry matter intake. Resulting protein to ME ratios (CP:ME) were 45.0, 63.3, 69.4, and 77.3 g of dietary CP per Mcal of ME. Rumen ammonia N and plasma urea nitrogen increased as CP level increased. Rumen pH, volatile fatty acids, and the acetate-to-propionate ratio were not affected with increasing CP levels. Greater urinary N excretion resulted in an increase in total N excretion with increasing CP levels. Apparent dry matter digestibility was similar for all diets, while apparent total tract N digestibility was lowest for the 11.9% CP level. Microbial N calculated from urinary excretion of purine derivatives increased with increasing CP levels. Holstein heifers between 153 and 196 kg consuming a diet at 2.0% BW as dry matter intake containing a CP level of 16.7% achieved a better synergistic relationship of dietary protein to energy (CP:ME of 63.3 g of CP per Mcal of ME) than the diets lower or higher in CP that were studied.     

Response of laying Japanese quails to graded levels of essential amino acids profile with reduced dietary protein

The effect on egg production of graded levels of ideal amino acids, combined with reduced protein in the diet, was investigated in 312 laying quails aged 6–18 weeks. The quails were offered six diets, each of which contained one of three levels of amino acids (85, 100 and 115% of essential amino acids (EAAs)) together with 5% or without fishmeal (FM) (3 × 2 factorial design). Each diet was offered to 26 replicated groups of two quails each. Hen‐day and hen‐housed egg production did not differ as a result of EAA level, protein type or their interaction during the overall period of egg production. Egg weight improved linearly (P < 0.01) with increased EAA levels, while egg mass output per bird per day remained similar at the 100 and 115% EAA levels. Quails fed higher (100 and 115%) EAA levels had an improved feed conversion ratio (P < 0.01) compared to birds fed 85% EAA. The gain in body weight during the laying period was higher (P < 0.01) at the 100 or 115% than at 85% EAA levels The ratio of egg mass or egg mass and live weight gain, together, to protein intake improved (P < 0.01) linearly with a decrease in EAA levels in the diets, while better (P < 0.01) energy efficiency (EE, energy intake: egg mass) and net EE (energy intake: egg mass plus gain) was obtained in higher EAA levels (100 or 115%). Protein and energy efficiencies remained similar due to protein type or interaction. Shape index, albumen index, yolk index, yolk colour and relative shell weight did not differ due to EAA levels, protein type or their interaction. Eggs laid from quails fed diets with 100% EAAs without FM and 115% EAAs with or without FM had higher shell thickness than those on 85% EAAs irrespective of protein type. The retention of nitrogen and calcium retention was higher (P < 0.01) at the 115% EAA level. The results indicated a dietary level of 100% EAA (185 g kg^?1 crude protein (CP)) with 12.13 MJ kg^?1 was suitable for laying quails of 6–18 weeks of age. Copyright © 2007 Society of Chemical Industry     

NUTRITIONAL AND TOXICOLOGICAL EVALUATION OF SINGLE-CELL PROTEIN PRODUCED FROM BACILLUS SP. KISRI-TM1A IN RATS

Single-cell protein (SCP) produced from a novel thermotolerant methylotrophic Bacillus sp. KISRI-TM IA was fed to groups of 10 male and 10 female Wistar rats at levels of 0, 10, 20, and 30 percent of total diets. The feeding of KISRI-TM IA did not adversely affect growth, feed intake or hematological values of rats. Water intake of male rats decreased with increasing level of SCP in the diet. Urinary pH showed dose-dependent reductions in both sexes. Plasma alkaline phosphatase and alanine aminotransferase were significantly (P<.05) reduced by increasing levels of dietary SCP. However, no significant (p>.05) abnormalities were observed in the weights or histopathological appearances of the organs. It was concluded that the KISRI-TM 1A SCP could serve as a potential dietary ingredient at levels of up to 30% for poultry, young lambs and calves.     

Effect of substituting soybean meal and canola cake with dried distillers grains with solubles at 2 dietary crude protein levels on feed intake,milk production,and milk quality in dairy cows

Dried distillers grain with solubles (DDGS) is an alternative source of feed protein for dairy cows. Previous studies found that DDGS, based on grains other than corn, can substitute for soybean meal and canola cake as a dietary protein source without reducing milk production or quality. As societal concerns exist, and in many areas strict regulation, regarding nitrogen excretion from dairy cows, the dairy industry has focused on reducing dietary protein level and nitrogen excretion. In the present study, we investigated the use of DDGS as a protein source, at a marginally low dietary crude protein (CP) levels, in a grass-clover and corn silage-based ration. The experiment involved 24 Holstein cows and 2 protein sources (DDGS or soybean-canola mixture) fed at 2 levels of CP (14 or 16%) in a 4 × 4 Latin square design. The aim of this study was to evaluate the effect of both protein source and protein level on feed intake, milk yield, and milk quality. The results indicated that feed intake, milk yield, and protein in milk increased when the protein level in the ration was 16% CP compared with 14%. We found no effect of substituting the soybean-canola mixture with DDGS. Moreover, no sensory problems were observed when comparing fresh milk with stored milk, and milk taste was unaffected by DDGS. Milk from cows fed DDGS had a slightly higher content of linoleic acid and conjugated linoleic acid (CLA 9–11), and lower content of C11 to C17 fatty acids than cows fed diets with the soybean-canola mixture. Cows fed the diets with 16% CP produced milk with higher oleic acids and lower palmitic acid content than cows fed 14% CP diets. To conclude, DDGS can substitute for a soybean-canola mixture without affecting feed intake, milk yield and quality, or sensory quality. Under the conditions of this experiment, feeding 16% CP compared with 14% CP in the ration can increase feed intake and milk production.     

Observations on the determination of protein quality by the Thomas–Mitchell method

In the Thomas–Mitchell method for the assessment of protein quality, metabolic faecal nitrogen (MFN) and endogenous urinary nitrogen (EUN) are used to adjust faecal and urinary N excretion on test diets so that true digestibility (TD) and biological value (BV) can be calculated. Using an experimental technique where the urine and faeces from young growing rats were collected every 2 days for an experimental period of 28 days, trends in the estimation of MFN and in the determination of TD and BV were examined. A diet containing 20 g egg albumen kg^?1 on an as fed basis (2.85 g N kg^?1 dry matter) has previously been found to be most applicable for the estimation of EUN. This diet was also found to be appropriate for the estimation of MFN. To examine the effect of a change from an ad libitum intake of a stock diet (containing 150 g protein kg^?1) to the restricted intake of a test diet (containing 80–100 g protein kg^?1) on the determination of TD and BV, three protein sources (egg albumen, casein+1% L -methionine and soya bean meal) were fed at two levels of intake: 9 and 15 g day^?1. The time taken for the faecal N excretion to stablilise was very similar with all diets at both levels of intake. The TD of all three protein sources at both levels of intake increased gradually with increasing lengths of preliminary period. However, this increase was not great, and had little effect on the determination of the BV. Stabilisation of urinary N excretion with the three diets depended on the quality of the protein and the amount fed. This led to variation in BV with lengthening preliminary periods, especially at the lower level of intake. Urinary N excretion, and consequently BV, stabilised most rapidly with the highest quality protein (egg albumen) at the highest level of intake. However, stabilisation of BV with the lowest quality protein (soya bean meal) did not occur until after a preliminary period of 12 days, even at 15 g day^?1. This preliminary period is considerably longer than that usually employed, and thus it appears that for many proteins the BV may have been assessed during a period before N retention has fully stabilised.     

摄食鱿鱼对人体血脂的影响

探讨高胆固醇海产品的摄食对正常人群血脂的影响。选取33名年龄在22～28岁之间的健康实验人员,每天食用100g鱿鱼,持续20d,并测定实验开始时、10d及20d后,血脂、血糖、肝功能指标以及血清脂肪酸组成的变化。结果显示：每日摄入100g鱿鱼,可明显降低受试者血清甘油三酯(TG)浓度(降低18%,P＜0.004),但对血清总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)、血糖浓度及肝功能标志酶活性均无显著影响。摄食鱿鱼后血清总脂肪酸组成发生明显变化,血清中二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)显著增加。提示每日100g鱿鱼的摄入不会影响健康人群血清胆固醇浓度,对动脉粥样硬化不具危险性。     

Effects of replacing canola meal as the major protein source with wheat dried distillers grains with solubles on ruminal function, microbial protein synthesis, omasal flow, and milk production in cows

A study was conducted to determine the effects of replacing canola meal (CM) as the major protein source with wheat-based dried distillers grains with solubles (W-DDGS) on ruminal fermentation, microbial protein production, omasal nutrient flow and animal performance. Eight lactating dairy cows were fed in a replicated 4 × 4 Latin square design with 28-d periods (20 d of dietary adaptation and 8 d of measurements). Four cows in one Latin square were ruminally cannulated for measurements of ruminal fermentation characteristics and flow of nutrients at the omasal canal. Cows were fed either a standard barley silage-based total mixed ration containing CM as the major protein supplement (0% W-DDGS, control) or diets formulated to contain 10, 15, and 20% W-DDGS (dry matter basis), with W-DDGS replacing primarily CM. Diets were isonitrogenous (18.9% crude protein) and contained 3.0, 3.2, 3.5, and 3.7% ether extract for 0, 10, 15, and 20% W-DDGS, respectively. Diets contained 50% forage and 50% concentrate. Inclusion of W-DDGS linearly increased dry matter intake (29.5, 31.2, 30.2, and 31.9 kg/d for 0, 10, 15, and 20% W-DDGS, respectively). The addition of W-DDGS in place of CM resulted in a 1.2- to 1.8-kg increase in milk yield (42.9, 44.7, 44.1, and 44.5 kg/d for 0, 10, 15, and 20% W-DDGS); however, a quadratic change in feed efficiency (i.e., milk yield/DM intake) occurred as the dietary level of W-DDGS increased. Treatments did not differ for milk fat, protein, and lactose concentrations; however, quadratic changes were observed in milk yields of fat (1.48, 1.56, 1.62, and 1.55 kg/d for 0, 10, 15, and 20% W-DDGS, respectively), protein (1.44, 1.46, 1.49, and 1.42 kg/d) and lactose (1.96, 2.02, 2.09, and 1.93 kg/d). Ruminal fermentation characteristics did not change except that the inclusion of 20% W-DDGS resulted in a decrease and a tendency for a decrease in molar concentrations of isobutyrate and total volatile fatty acids, respectively. Omasal flow of total bacterial nonammonia N (NAN) and bacterial efficiency (g of total bacterial NAN flow/kg of organic matter truly digested in the rumen) were not different among diets; however, feeding W-DDGS resulted in a quadratic increase in nonammonia nonbacterial N flow at the omasal canal (271, 318, 336, and 311 g/d for 0, 10, 15, and 20% W-DDGS, respectively). These data indicate that W-DDGS can substitute for CM as the major protein source in dairy cow diets without negatively affecting ruminal fermentation, microbial protein production, and omasal nutrient flow, and can potentially increase dry matter intake and milk yield.     

Influence of rapeseed cake, linseed cake and hemp seed cake on laying performance of hens and fatty acid composition of egg yolk

In hens the effects of expeller/cakes from rapeseed, linseed, and hemp seed were investigated on feed intake, laying performance and fatty acid composition of egg yolk. A total of 216 individually caged laying hens were allocated to nine dietary treatments (5, 10, 15 % cake) and fed for six laying months. For feed intake, egg mass production and feed-to-egg mass ratio at 15 % dietary cake level a significant lower performance was shown compared with the 5 and 10 % cake level groups. Also interaction was significant for all these parameters, indicating that the cake level acted differently for the three cakes. The egg mass production was lower in the linseed cake than in the hempseed groups and the hens fed the linseed cake needed significantly more feed per kg egg mass compared with both the other cakes tested. Increasing dietary level of all oil seed cakes lowered the yolk percentage and increased the egg white percentage. Increased dietary levels of all three oil seed cakes lowered the percentages of most saturated fatty acids and also the percentages of the monounsaturated fatty acids. The linoleic acid and the linolenic acid as polyunsaturated fatty acids were heightened by increasing the cake levels from 5 to 10 and 15 % in the diet. The results allow the conclusion that compound feeds with up to 10 % of cakes does not negatively influence the laying performance of hens and provides the possibility of the enrichment of yolk fat with polyunsaturated fatty acids.     

The quality and sensory attributes of cookies supplemented with fluted pumpkin (Telfairia occidentalis Hook) seed flour

Replacing wheatflour (WHF) with defatted fluted pumpkin (Telfairia occidentalis Hook) seed flour (FPF) at levels of 0–25% was investigated for its effect on chemical, physical, sensory and nutritional properties of cookies (biscuits). Protein quality was evaluated by using weanling albino rats fed a diet of cookies, which were formulated to supply 10% protein, with a casein diet as a control. Up to 15% substitution of WHF with FPF produced acceptable cookies with spread ratio, hardness, colour and flavour similar to the control (100% WHF) cookies. Use of higher levels (20–25%), however, resulted in reduction in these quality attributes. When WHF was replaced with 15% FPF, there was an increase of 84.6% in crude protein, 62.9% in calcium, 131.0% in potassium and 61.6% in phosphorus contents of composite cookies. There were no significant (P > 0.05) differences between the values obtained for protein efficiency ratio, net protein ratio and true digestibility of cookie diets containing 15–20% FPF, and casein when fed to rats.     

Responses of intake,digestibility and nitrogen utilisation in goats fed low‐quality roughages supplemented with tree foliages

BACKGROUND: A meta‐analysis of data containing 127 different dietary treatments with 593 goats from 30 published studies was performed to explain the effects of foliage supplementation to low‐quality roughages on intake, digestibility and N utilisation in goats. RESULTS: Basal dry matter (DM) intake decreased linearly with increasing foliage level (FL) in diets and foliage crude protein (CP) intake, whereas total DM intake increased linearly with increasing FL and CP intake from foliages and quadratically with increasing concentration of neutral detergent fibre (NDF) in foliages. The digestibility of DM and CP increased linearly with increasing FL and CP concentration in basal roughages and foliage CP intake. The greater concentration of NDF in foliages and roughages decreased CP digestibility linearly. Intakes of digestible DM and CP increased quadratically with increasing FL, with plateau levels of 36.4 and 5.52 g kg^?1 (body weight)^0.75 in response to 490 and 740 g kg^?1 FL respectively. Faecal N, urinary N and N retention increased linearly with increasing FL and foliage CP intake. CONCLUSION: Responses of goats fed basal roughages supplemented with foliages are influenced by the quality and quantity of foliages and quality of roughages. Up to 490 g kg^?1 FL can be incorporated in diets for better feed utilisation and animal performance, beyond which nutrient utilisation may be adversely affected. Copyright © 2009 Society of Chemical Industry     

Value of yeast protein for poultry feeds

Evaluation of yeast as a main source of protein to replace fish meal or soybean meal in chicken feeds was reviewed in the attempt to establish another source of protein in chicken nutrition. Various substrates used for yeast growth were compiled. The chemical composition and vitamin B content of yeasts were summarized. Amino acids and nucleic acids of yeasts as well as net protein utilization, true digestibility, biological value, and protein efficiency ratio of yeasts and other protein foods were discussed to ascertain the nutritive value of yeast proteins. The results of studies conducted under practical conditions where yeasts were used to replace the extracted soybean meal and fish meal individually or together in commercial feeds were tabulated in detail in terms of growth, feed intake, feed conversion ratio, etc. It appeared that the growth of broilers fed the feeds containing yeast at a level of up to 15 to 20% was almost identical when yeast was added in place of soybean meal, but somewhat retarded when yeast was added in place of all fish meal and part of soybean meal. Poorer growth was observed with an increase in dietary yeast above this level. It was recommended to add synthetic DL‐methionine to yeast‐based rations for poultry in order to obtain good growth performance. It has been demonstrated that appetite and growth rates of broilers maintained on yeast‐containing diets properly balanced in energy, protein, calcium, and phosphorus were superior to those in which the nutrients were not carefully adjusted. The blood plasma uric acid levels of broilers were not affected by levels of up to 20% n‐paraffin yeast in the diet. Up to 20% of the diet can be composed of alkane‐grown yeasts without any deleterious effects on egg quality or reproductive performance of laying and breeding hens. Chickens fed for prolonged periods of time with hydrocarbon‐grown yeasts failed to show any changes in protein metabolism, hematologic, or morphological indices which might be associated with undesirable characteristics of poultry products.     

Cassava (Manihot esculenta Crantz) Flour Fortification with Soy Flour

A flour was prepared from “sweet”cassava tubers. Cyanogenic acid content was 24.4 mg/kg of flour. Proximate analysis was made; crude protein content was 2.1%. Soy flour with 53.8% protein was used to fortify cassava flour at 5, 10, 15, and 20%. Quality of the cassava flour protein was very low; addition of soy raised the quality. Protein efficiency ratio of 80% cassava-20% soy composite flour was 1.55 when fed to rats. Rats receiving diets with 100% cassava, and 95% cassava-5% soy lost body weight. Diets with 90% cassava-10% soy caused no change in body weight. Soy softened the dough made from cassava-soy flours. Therefore, the smaller amounts of water needed to maintain a uniform dough consistency with increased levels of soy were determined. Dough became darker, more red and more yellow with increased amounts of soy. Panel scores for dough were increased with increased levels of soy up to 15%. Scores for appearance and eating quality for dough with 20% soy were lower than scores for dough containing no soy.     

Organoleptic and nutritional evaluation of wheat breads supplemented with soybean and barley flour

Supplementations of soy (full fat and defatted) and barley flours to wheat flours at 5, 10, 15 and 20% levels were carried out to test the effects on organoleptic and nutritional evaluation of the supplemented bread. Additions of 15% barley flour, 10% soy flour (full fat and defatted), 15% barley plus full fat soy flour and 15% barley plus defatted soy flour to wheat flour produced acceptable breads. However, substitution of soy (full fat and defatted) and barley flours to wheat flour separately and in combinations at 20% levels did not produce organoleptically acceptable bread. Various nutritional parameters, such as protein, fat, total lysine, protein digestibility (in vitro), sugars, starch digestibility (in vitro), total and available minerals, antinutrients, dietary fibre and β-glucan were determined in supplemented and control bread. Increasing the level of substitution from 5 to 10% of full fat and defatted soy flour to wheat flour significantly (P<0.05) increased protein (from 12.1 to 13.7 and 12.4 to 13.8%), lysine (from 2.74 to 3.02 and 2.76–3.05 mg/100 g protein) and total calcium (from 70.2 to 81.4 and 71.9–81.8 mg/100 g) contents. However, there was also an increase in phytic acid (238–260 and 233–253 mg/100 g), polyphenol (324–331 and 321–329 mg/100 g) and trypsin inhibitor activity (193–204 and 193–198 TIU/g). When barley flour was substituted separately, and in combinations, with full fat and defatted soy flour up to 15%, this significantly increased the contents of protein, total lysine, dietary fibre and β-glucan. It may be concluded that breads supplemented with barley and defatted soy flour, up to a 15% level, are organoleptically and nutritionally acceptable.     

Digestion and nitrogen utilization in dairy heifers limit-fed a low or high forage ration at four levels of nitrogen intake

The hypothesis of this experiment is that a low-forage (LF) ration will be utilized with greater efficiency than a high-forage ration (HF) by dairy heifers and that the response will be affected by level of N intake. To test this hypothesis, 8 Holstein heifers (beginning at 362 ± 7 kg and 12.3 ± 0.4 mo) were fed 8 rations according to a split-plot, 4 × 4 Latin square design. Treatments were formulated to contain 25 or 75% forage (corn silage and chopped wheat straw) and fed at 4 levels of N intake [0.94 (Low), 1.62 (MLow), 2.30 (MHigh), 2.96 (High) g of N/kg of metabolic body weight per day]. Diets were limit-fed to maintain equal intake of metabolizable energy. Blood samples were collected over d 19 to 20, and feces and urine were collected for 8 d per 28-d period. Organic matter (OM) intake was greater for heifers fed HF, but, due to increased OM digestibility of LF (74.0 vs. 67.6% ± 0.9), digestible OMI was unaffected by forage level. Organic matter digestibility was affected by an interaction between forage level and N intake, increasing to a plateau of 78.01% at 18.43% crude protein for LF-fed and 68.78% at 13.90% crude protein for HF-fed heifers. Apparent N digestibility was greater for heifers fed LF and increased from 47.7 to 80.8% between Low and High N intake. Less N appeared in the feces of heifers fed LF than HF (45.56 vs. 52.60 g/d). Urea-N excretion was not different between forage levels, but increased linearly with N intake. Concentration of plasma urea-N was significantly higher for LF and with increasing N intake. Urea clearance rate (L/h) did not differ between forage levels and increased, but at a decreasing rate, as N intake increased. A significant interaction resulted from urea clearance increasing at a greater rate and resulting in higher values for HF, whereas clearance of urea for heifers fed LF resulted in significantly lower maximal values. Like urea-N excretion, daily urinary N excretion was affected only by N intake. Retained N responded linearly to increased levels of N intake. The significant reduction observed in fecal N excretion for LF was counterbalanced by numerical increases in urinary N excretion so that total N excretion and retention were not different between forage levels. The percentage of N intake that was retained only tended to be affected by an interaction and was not significantly affected by forage level. It is concluded that increasing N intake increases the digestibility of OM, the magnitude of which depends on the level of dietary forage provided. Furthermore, differences in N utilization between LF and HF in this trial were small and were not evident until N intake increased to impractical levels.