Increase In Dietary Level Research Articles

Effects of methods of exposure to Eastern red cedar foliage on cedar consumption by Boer crossbred wether goats

Twenty-four Boer crossbred yearling wethers ( 23.5±2.31 kg initial BW) were used to determine effects of stepwise increases in dietary level of Eastern red cedar ( Juniperus virginiana) foliage (CF), compared with a constant relatively high level and subsequent availability of low-quality forage, on present and later consumption of CF. Animals were penned individually in Phases 1 (8 week) and 3 (2 week), and during Phase 2 (6 week) wethers were kept in a pasture not containing cedar trees and were fed wheat hay. In Phase 1 a concentrate-based diet (CBD, 12.6% CP and 35.5% NDF) was offered at approximately 85% of the maintenance energy requirement alone (Control) or with weekly stepwise (Step) increases in level of substitution of CF for CBD (0, 1.25, 2.5, 5, 10, 15, 20, and 25% in week 1–8, respectively; DM basis) or substitution of 25% CF in week 2–8 (Set). In Phase 3 (2 week), all wethers were offered the diet of 75% CBD and 25% CF as previously, without or with separate free-choice access to low-quality grass hay. CF was harvested weekly, refrigerated and hand-mixed with CBD prior to feeding. In Phase 1, intake of CF as a percentage of that offered was greater ( P<0.05) for Step versus Set in week 2–8 (week 2: 84 and 68; week 3: 86 and 48; week 4: 89 and 56; week 5: 90 and 71; week 6: 96 and 81; week 7: 93 and 63; week 8: 96 and 84), although CF intake as g per day was greater ( P<0.05) for Set versus Step in all but week 7 and 8. In Phase 3, CBD intake was similar among treatments, and hay intake when offered averaged 149, 134 and 124 g per day for Step, Set and Control, respectively. For wethers not receiving hay, CF intake as g per day for Step was greatest among treatments ( P<0.05) but was not different from treatments with offered hay (67, 37, 30, 55, 53 and 56 g per day for Step, Set and Control without and with hay, respectively; S.E.=7.1). Similarly, CF intake as a percentage of that offered ranked ( P<0.05) Step>Set>Control without hay, but was not different between Step without hay and treatments with hay (78, 41, 34, 61, 57 and 60% for Step, Set and Control without and with hay, respectively; S.E.=7.6). Concentrations of various blood constituents at the end of Phases 1 and 3 did not indicate adverse health effects of CF consumption. In conclusion, gradual increases in dietary level of CF deserve further research as a potential means to elevate present and future CF consumption, with attention also directed to effects of type and level of other feedstuffs offered.

Replacement of maize by rumen filtrate fermented corn-cob in layer diets

Laying hens (50 weeks in-lay) were fed for 8 weeks on diets containing corn-cobs fermented with rumen filtrate. The fermented corn-cob was included in the diets at 0%, 5.0%, 10.0%, 15.0% and 20.0% of the total diet at the expense of maize. Feed intake was not significantly ( P>0.05) different, although birds on the control diet consumed slightly more feed than birds on the fermented corn-cob based diets. Hen day production and feed per dozen eggs decreased with increase in dietary level of corn-cob ( P<0.05). Yolk colour was significantly ( P<0.05) affected, rumen filtrate fermented corn-cob appear to promote better yolk coloration. Egg weight and shell thickness were not significantly influenced by dietary treatment. The overall results appear to suggest that rumen filtrate fermentated corn-cob could provide a material that holds promise as a good alternative to maize because of its enhanced crude protein value and reduced crude fibre content.

Reducing Crude Protein and Increasing Limiting Essential Amino Acid Levels with Summer-Reared, Slow- and Fast-Feathering Broilers

Values for the limiting essential amino acids (EAA), according to AgriStats averages for 1999 [1], that are used in broiler feed formulation generally exceed those advocated by NRC [2]. In turn, satisfying these general industry levels for TSAA, lysine, and threonine with commercially available purified forms enables CP to be decreased [1] below minimums recommended by NRC [2]. Imposing further increases in dietary levels of the three most limiting EAA while forcing a decrease in CP was evaluated as a means to improve performance of summer reared broilers. Average values from AgriStats, Inc. [1] for ME, CP, lysine, TSAA, and threonine served as the basis in developing an industry-representative, four-feed regimen while NRC [2] minimum recommendations were used for all other EAA. Four factorial feed treatments involved a forced reduction of 1% CP from the representative level combined with 10% increases in lysine, TSAA, and threonine from industry levels. Slow- and fast-feathering males received each of the four feeds in floor pens to 47 d of age. Responses attributed to alteration in CP, EAA, and feathering were largely independent of one another. Alteration of CP elicited the most dominant effects; body weight gain, amount of abdominal fat, chilled carcass yield, grade A, and skinless boneless breast meat were favored using the industry standard, whereas the converse was true for feed conversion. Accumulation of abdominal fat when the CP was reduced was less extensive with slow- than fast-feathering males. Presumably, additional productive energy was derived from an improved overall amino acid balance with decreased CP; however, this added energy and additional feather cover appeared to complicate an already close relationship with effective protein. Providing additional amounts of lysine, TSAA, and threonine only enhanced early live performance and likely occurred because all other EAA were more than satisfactory to realize additional benefits.

Alpha-tocopherol downregulates gulonolactone oxidase activity in sturgeon.

Gulonolactone oxidase (GLO) is the enzyme responsible for the last step of ascorbic acid biosynthesis. The aim of this study was to investigate the effect of dietary alpha-tocopherol and ascorbic acid on GLO activity in a lower vertebrate, the white sturgeon (Acipenser transmontanus). Both alpha-tocopherol and ascorbic acid modulated renal GLO activity. The increase of dietary levels of alpha-tocopherol and/or ascorbic acid significantly raised the liver concentrations of these two antioxidants and concomitantly lowered kidney's GLO activity. The results suggest that the enzyme of ascorbic acid synthetic pathway responded to the animal's antioxidant status and that its activity was downregulated by alpha-tocopherol. This is the first record of alpha-tocopherol being involved in the regulation of ascorbic acid synthesis. This new observation may provide a hypothesis for the evolutionary loss of GLO expression in teleost fishes.

Modulation of arachidonate and docosahexaenoate in Morone chrysops larval tissues and the effect on growth and survival.

The extent to which extreme dietary levels of arachidonate (AA) and/or docosahexaenoate (DHA) modulate lipid composition in the body tissues and consequently affect growth and survival in freshwater Morone larvae species was examined. White bass, M. chrysops, larvae (day 24-46) were fed Artemia nauplii enriched with algal oils containing varying proportions of AA and DHA (from 0 to over 20% the total fatty acids). Growth was significantly reduced (P< 0.05) in larvae fed a DHA-deficient Artemia diet. Increases in dietary levels of AA also were associated with a significant growth reduction. However, the inhibitory effect of AA on larvae growth could be suppressed by the dietary addition of DHA (at a level of 21.6% of the total fatty acids in enrichment lipids). Larval brain + eyes tissue accumulated over 10 times more DHA than AA in its structural lipids (phosphatidylcholine, phosphatidylethanolamine) at any dietary ratio. In contrast, DHA accumulation, as compared to AA, in gill lipids declined considerably at higher than 10:1 DHA/AA tissue ratios. DHA and eicosapentaenoic acid (EPA) contents in brain + eyes tissue were most sensitive to competition from dietary AA, being displaced from the tissue at rates of 0.36 +/- 0.07 mg DHA and 0.46 +/- 0.11 mg EPA per mg increase in tissue AA, and 0.55 +/- 0.14 mg AA per mg increase in tissue DHA. On the other hand, AA and EPA levels in gill tissue were most sensitive to dietary changes in DHA levels; AA was displaced at rates of 0.37 +/- 0.11 mg, whereas EPA increased at rates of 0.68 +/- 0.28 mg per mg increase in tissue DHA. Results suggest that balanced dietary DHA/AA ratios (that allow DHA/AA ratios of 2.5:1 in brain + eyes tissue) promote a high larval growth rate, which also correlates with maximal regulatory response in tissue essential fatty acids.

Effects of n−3 HUFA levels in broodstock diet on the reproductive performance and egg and larval quality of the Japanese flounder, Paralichthys olivaceus

We investigated the effect of dietary n−3 highly unsaturated fatty acids ( n−3 HUFA) on egg and larval quality in the Japanese flounder Paralichthys olivaceus. Diets with similar proximate composition, but different n−3 HUFA (0.4%, 0.8%, and 2.1%) levels were fed to broodstock from 3 months before and during the spawning season. Spawning was observed from March to June. Total egg production was highest in fish fed the lowest n−3 HUFA, and decreased with the increase of dietary n−3 HUFA. Percentages of buoyant eggs and hatched larvae were independent of dietary treatment. In contrast, the percentage of normal larvae, survival of larvae at 3 days post hatching (DPH), and the starvation tolerance index correlated with dietary n−3 HUFA levels. n−3 HUFA level in eggs increased with the increase of dietary level. Higher level of arachidonic acid (AA) was also found in eggs that showed high quality, reflecting dietary fatty acids. The results of this study clearly show that n−3 HUFA level in broodstock diet has an effect on the quality of eggs and larvae in the Japanese flounder and suggested that AA may have positive effect on the improvement in spawning quality of flounder.

Omega-3 polyunsaturated fatty acids in rodent models of breast cancer.

Quantitative increases in certain dietary fats promote mammary tumor growth, but the experimental data indicate that this tumor promoting capability is not equally expressed by all fatty acid families. There is a large body of evidence from experiments using either carcinogen-induced or transplanted animal mammary tumor models, as well as in vitro studies, which demonstrates that the omega-6 polyunsaturated fatty acids (PUFA) promote mammary tumor development more effectively than omega-3 PUFA. These data indicate that increases in the dietary levels of omega-6 PUFA enhance tumor development, while equivalent increases in dietary levels of omega-3 PUFA often delay or reduce tumor development. Several theoretical mechanisms have been proposed for these contrasting results, but as yet, no definitive explanation has been universally accepted.

Dietary ω-3 polyunsaturated fats and breast cancer

Although early experimental investigations concluded that quantitative increases in dietary fat promote mammary tumor growth, recent studies have indicated that not all fatty acid families equally express this tumor-promoting capability. This article provides an overview of some of the experimental evidence demonstrating that the ω-6 polyunsaturated fats have significantly different mammary tumor-promoting capabilities from those of the ω-3 polyunsaturated fats. Collectively, these data indicate that whereas increasing dietary levels of ω-6 polyunsaturated fatty acids enhances tumor development, equivalent increases in dietary levels of ω-3 polyunsaturated fatty acids delay or reduce tumor development. Some of the theoretical mechanisms proposed for these contrasting results and their supporting experimental data are discussed.

Dietary omega-3 polyunsaturated fats and breast cancer.

Although early experimental investigations concluded that quantitative increases in dietary fat promote mammary tumor growth, recent studies have indicated that not all fatty acid families equally express this tumor-promoting capability. This article provides an overview of some of the experimental evidence demonstrating that the omega-6 polyunsaturated fats have significantly different mammary tumor-promoting capabilities from those of the omega-3 polyunsaturated fats. Collectively, these data indicate that whereas increasing dietary levels of omega-6 polyunsaturated fatty acids enhances tumor development, equivalent increases in dietary levels of omega-3 polyunsaturated fatty acids delay or reduce tumor development. Some of the theoretical mechanisms proposed for these contrasting results and their supporting experimental data are discussed.

Partial and total replacement of fish meal with soybean meal and distillers' by-products in diets for pond culture of the freshwater prawn ( Macrobrachium rosenbergii)

This study was conducted to evaluate the effect of partially or completely replacing fish meal with soybean meal and distillers' dried grains with solubles (DDGS) in diets for pond-raised freshwater prawns. Juvenile prawns averaging 0.51±0.27 g were stocked into nine 0.02-ha earthen ponds at 39,520/ha. Three isonitrogenous diets (32% crude protein) containing 15, 7.5 or 0% fish meal were fed to prawns in triplicate ponds. A variable percentage of soybean meal and a fixed percentage (40%) of DDGS replaced fish meal. Average yield, survival, individual weight, and feed conversion did not differ significantly ( P<0.05) among shrimp fed the three diets. When averaged over the three diets, results were: yield, 1268 kg/ha; survival 78.1%; individual weight 42 g; and feed conversion 2.9. Replacement of fish meal caused increases in dietary levels of glutamine, proline, alanine, leucine, and phenylalanine, and decreases in aspartic acid, glycine, arginine, and lysine levels in the diets. Changes in fatty acid profiles of the diets were: increased concentrations of 16:0, 18:2 n-6, and 20:1 n-9, and decreased concentrations of 14:0, 16:1 n-7, 18:1 n-9, 18:3 n-3, 20:4 n-6, 20:5 n-3, 22:5 n-3 and 22:6 n-3. Results indicate that fish meal can be partially or totally replaced with soybean meal and distillers' by-products in diets for pond production of freshwater prawns in temperate areas.

Interactive effects of dietary silicon, copper, and zinc in the rat

A factorial rat experiment using two dietary concentrations each of copper, zinc, and silicon was conducted to identify areas in which interrelationships involving silicon may exist. The concentrations used were (mg/kg of diet): copper, 1 and 5; zinc, 2 and 12; and silicon, 5 and 270. An antagonism between silicon and zinc, whereby increases in dietary levels of either one resulted in a reduction in blood plasma concentrations of the other, was demonstrated. The depressing effect of silicon on plasma concentrations of zinc and on alkaline phosphatase occurred only in zinc-deficient rats. However, silicon had no effect on growth. Effects on aortic composition, interpreted as beneficial, accompanied increases in the silicon content of copper-deficient diets. Silicon-dependent increases in the chloroform-methanol extractable fraction of aorta closely approximated a similar response to copper. High dietary silicon increased aortic elastin in copper-deficient rats when dietary zinc was adequate. The aortic effects of silicon, while mimicking the gross effects of copper, occurred in the absence of any silicon-related changes in blood copper concentrations. Interrelationships of silicon with other elements, particularly copper and zinc, may warrant consideration in future nutritional and metabolic studies.

Effect of dietary 5-hydroxy-L-tryptophan for prevention of scoliosis in tryptophan-deficient chum salmon fry.

Tryptophan (Trp)-deficient diets (Trp 50mg/100g diet) supplemented with graded levels of 5-hydroxy-L-tryptophan (5-HTP; 0.1, 1, 10 & 100mg/100g diet) were fed to chum salmon fry Oncorhynchus keta to clarify whether 5-HTP, the precursor of serotonin (5-HT), prevents scoliosis caused by Trp deficiency and affects the levels of neurotransmitters in fish brain. The administration of the dose of less than 10mg of 5-HTP/100g diet caused scoliosis in 62-65% of fish atfer 4 weekrearing, whereas the increase in dietary level of 100mg reduced this value to 1.7%. 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) contents in the brain of the fish fed Trp-deficient diet containing 100mg 5-HTP/100g diet as well as those of Trp-sufficient diet (Trp 290mg/100g diet) were higher than those of the other dietary groups. The brain norepinephrine (NE) contents showed a tendency to rise as the supplemental level of 5-HTP increased. These results clearly indicate that the oral administration of 5-HTP up to the level of 100mg/100g dict or 40mg/kg body weight/day can almost completely prevent occurrence of scoliosis. Incidence of scoliosis in the fish fed Trp-free diet (Trp 0%) was only 15% even though brain 5-HT content of this group was in the same range as those fed Trp-deficient diet containing supplemental 5-HTP up to 10mg/100g diet. However, the brain NE and dopamine contents of the former were almost the same as those fed Trp-sufficient diet. These findings suggest that catecholamine may be also involved in an occurrence of scoliosis and that there is a considerable physiological difference between complete absence of Trp and intake of small quantity of Trp.

EFFECTS OF INCREASING DIETARY LEVELS OF COMMERCIALLY HEATED SOYBEANS ON PERFORMANCE, NUTRIENT RETENTION AND CARCASS QUALITY OF BROILER CHICKENS

Two experiments were conducted to investigate the effects of supplementing broiler diets fed to 6 wk of age, with 0, 10, 20 or 30% of commercially heated unextracted soybeans (T.I.A. 3.9 mg g−1). Birds fed soybeans consumed less feed in the 0- to 21-d starter period and this was associated with reduced weight gain (P &lt; 0.05) and increased feed intake: weight gain (P &lt; 0.05). There was a decrease in calcium, phosphorus, magnesium and fat retention with feeding of soybeans and this effect was most pronounced with the 30% inclusion level. Diet ME was also reduced with increased use of soybeans (P &lt; 0.05). However, there was a decrease in digesta and fecal soap concentration with an increase in dietary levels of heated ground soybeans (P &lt; 0.01). While carcass weight followed a trend similar to that of weight gain (P &lt; 0.01), there was no difference between treatments for percent carcass yield (P &lt; 0.05). Soft fat depot areas were observed when soybean oil was the primary dietary fat. Fatty acid analysis of carcass fat confirms a high degree of unsaturation for birds fed 30% heated soybeans. However, this feature was not unduly objectionable nor did it affect carcass grading (P &gt; 0.05). Key words: Heated soybeans, broiler performance, carcass quality

ROLE OF SOAP FORMATION IN UTILIZATION OF FULL-FAT CANOLA BY LAYING HENS

Laying hens (35 w old) were offered diets containing 0, 5, 10, 15 or 20% full-fat canola over an 8-wk period. There were no significant effects of the dietary treatments on egg production, egg weight or egg shell quality (P &gt; 0.05). Although laying hens fed each of the diets consumed similar quantities of feed (P &gt; 0.05), birds consuming diets containing 15 or 20% full-fat canola gained less weight compared to birds fed lower levels of full-fat canola (P &lt; 0.01). There was no difference among treatments for apparent retention of nitrogen, calcium, phosphorus or magnesium (P &gt; 0.05) However there was a decrease in both fat retention and energy utilization with an increase in dietary level of full-fat canola (P &lt; 0.01). There was no difference in the fat content of the eggs as affected by the dietary treatments and with the exception of a decrease in proportion of palmitic acid (P &lt; 0.05) and increase of linolenic acid (P &lt; 0.05) increased inclusion of full-fat canola had little effect on egg fatty acid content. There was no significant effect on the dietary treatments on bone ash and bone mineral content. These data suggest that while high levels of full-fat canola have little effect on performance during short-term studies, there is concern of the birds' ability to digest canola lipids. Key words: Full-fat canola, laying hen, bone mineralization

Effects of Increasing Dietary Levels of Full-Fat Canola on Performance, Nutrient Retention, and Bone Mineralization

Day-old male broiler chickens were fed diets containing 0, 5, 10, 15, or 20% raw, ground, full-fat canola for a period of three weeks. Increasing the dietary proportion of full-fat canola significantly reduced feed intake (P<.05) and weight gain (P<.01), without altering feed:gain ratio.Diet had no significant effect on protein retention although there was a significant decrease in fat retention with an increase in dietary levels of full-fat canola (P<.01). This was accompanied by a significant decrease in metabolizable energy (P<.01). Increasing the proportion of dietary full-fat canola significantly reduced the concentration of soap in the digesta (P<.05) and excreta (P<.01). There was no significant effect of the dietary treatments on calcium or phosphorus retention. There was also no effect of the dietary full-fat canola on bone ash, bone calcium, or phosphorus content.

Zinc homeostasis in man: studies using a new stable isotope-dilution technique.

A new method has been developed for the study of zinc metabolism in man using the stable isotope 67Zn. The technique involves intravenous infusion of the isotope followed by measurements of the plasma and faecal enrichments over a period of days. A procedure for the analysis of Zn isotopes in plasma and faeces is described which requires the separation of Zn from other elements using the chelator dithizone before analysis by thermal-ionization mass spectrometry. The stable isotope technique has been used in conjunction with a metabolic balance study to obtain measurements of Zn absorption and gastrointestinal secretion in a normal subject. Preliminary measurements of the size of the exchangeable pool of Zn have been made as have estimates of the rates of plasma and whole-body Zn turnover. Following an increase in dietary Zn the body appeared to respond in two ways. The gastrointestinal secretion of Zn increased immediately, but only by a relatively small amount. The absorption of Zn initially increased in proportion to the increase in dietary levels but then decreased within 4 d by an amount sufficient to restore Zn balance.

Excessive hepatic accumulation of intracellular Ca 2+ in chlordecone potentiated CCl 4 toxicity

The possible role of Ca 2+ in chlordecone potentiation of CCl 4 hepatotoxicity was examined in male Sprague-Dawley rats. The rats were maintained on a diet containing either 0, 10, 25, 50 or 100 ppm chlordecone for 15 days. On day 15, they received a single i.p. injection of corn oil (1 ml/kg) or CCl 4 (100 μl/kg) in corn oil vehicle. The animals were killed at 1, 6, or 12 h after the oil or CCl 4 challenge for hepatic Ca 2+ determinations. Ca 2+ in whole liver, mitochondria, microsomes or in cytosolic fraction was unaltered in any group of animals receiving chlordecone + oil treatments, indicating that chlordecone alone does not alter whole liver content or hepatic subcellular distribution of Ca 2+, even after exposure to toxic levels (50 or 100 ppm). Administration of CCl 4 at an otherwise non-toxic dose to chlordecone treated animals resulted in significant increases of whole liver and subcellular Ca 2+ as compared to chlordecone alone and CCl 4 alone with a characteristic biphasic response. These increases were significant at all 3 time points in whole liver, cytosolic and mitochondrial fractions. Microsomal Ca 2+ increased only at 12 h after CCl 4. The increases were all progressive with increases in dietary levels of chlordecone, indicating that chlordecone-induced sensitivity is responsible for CCl 4 elicited perturbations in whole liver and intracellular Ca 2+ levels. This study suggests that chlordecone modifies the liver plasma membrane to amplify the CCl 4 elicited perturbations in hepatocellular Ca 2+ homeostasis especially during 6–12 h after CCl 4 administration. This perturbation of Ca 2+ homeostasis may be related to the arrested repair and regeneration of damaged liver tissue leading to progressive deterioration observed in previous histomorphometric studies.

Municipal sludge management: Health aspects of crop uptake of cadmium from sludge-amended soil and recommendations for regulation

Regulations have been proposed by the United States Environmental Protection Agency to promote the proper management of sludge disposal on croplands. The application of municipal sludge to croplands raises serious questions concerning the increase in dietary levels of metals resulting from metal uptake by crops. A model is presented that affords a quantitative estimate of the dietary increase of metals when foods are derived from sludge-amended soil. If a diet or part of a diet is derived completely from sludge-amended soil, it is likely to be excessive in cadmium and pose a clear health hazard. Recommendations designed to reduce the potential health threat of excessive metals in the diet are presented.