Dietary restriction, caloric value and the accumulation of hepatic fat

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of dietary organic selenium and zinc on the internal egg quality of quail eggs for different periods and under different temperatures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dietary protein and energy requirements of juvenile freshwater angelfish

Avaliaram-se as exigências nutricionais de proteína e energia em juvenis de acará-bandeira (Pterophyllum scalare). Utilizou-se delineamento inteiramente casualizado, em esquema fatorial 3 × 2, com três níveis de proteína bruta (26, 30 e 34%), dois de energia digestível (3.100 e 3.300 kcal/kg de ração) e três repetições. Juvenis com peso médio de 2,33 ± 0,26 g foram distribuídos em aquários contendo 25 litros de água, temperatura controlada (26 ± 1ºC) e filtro biológico, na densidade de estocagem de seis animais por aquário. Os peixes foram alimentados à vontade às 9, 14 e 16h30. Na análise do desempenho produtivo, foram avaliados o peso final, o comprimento final, o ganho de peso, o consumo de ração, a conversão alimentar, a taxa de crescimento específico, a taxa de eficiência protéica e o fator de condição. As dietas contendo 26% PB proporcionaram maiores valores para taxa de eficiência protéica apenas em relação às dietas contendo 34% PB. As exigências nutricionais de proteína e energia em juvenis de acará-bandeira podem ser atendidas com dietas contendo 26% PB e 3.100 kcal ED/kg.

HAEMONCHUS PLACEI IN CALVES - EFFECTS OF DIETARY-PROTEIN AND MULTIPLE EXPERIMENTAL-INFECTION ON WORM ESTABLISHMENT AND PATHOGENESIS

An experiment was conducted to examine the influence of dietary protein and immunisation on parasite establishment and pathogenesis of Haemonchus placei in calves. Four groups of 4-6-month-old worm-free calves (n=4) were given a low protein diet (LP) containing 213 g crude protein (CP) per head per day or a high-protein diet (HP) containing 469 g per head per day CP. Five weeks later, calves in one of the two groups of each dietary treatment were given 50 000 H. placei infective larvae (L(3)). Twenty-five days later, infection in these groups was terminated by dosing with oxfendazole, This immunisation process was repeated 4 days later. Four days after termination of the second immunisation all calves were challenged with 100 000 L(3). Five weeks later, all calves were slaughtered for abomasal worm counts. Worm establishment was lower in the immunised groups; however, only the HP-I group showed a significant reduction (P < 0.05). All calves gained weight during the first 13 week period, and after challenge the non-immunised groups lost weight, independent of the level of protein in the diet (P < 0.05), Packed cell volume values for all treatments only dropped after challenge (P < 0.05) and the HP-immunised group presented values significantly higher when compared with the other treatments, All calves were hypoproteinaemic and hypoalbuminaemic at the end of the experiment, regardless of the treatment. Immunised calves showed a normocytic normochromic anaemia, while the non-immunised groups presented a microcytic normochromic anaemia.

INFLUENCE OF DIETARY-PROTEIN INTAKE AND RECOMBINANT HUMAN SOMATOTROPIN ADMINISTRATION ON GROWTH AND BODY-COMPOSITION OF JUVENILE TAMBACU (A PIARACTUS-MESOPOTAMICUS X COLOSSOMA-MACROPOMUM CROSS)

This experiment was undertaken to study the interaction between level of dietary protein and recombinant human somatotropin (rhGH) administration on performance and body composition of juvenile tambacu (a crossbred Brazilian fish). A total of 72 juvenile tambacu, initially weighing and measuring (mean +/- s.e.m.) 23 +/- 2 g and 9 +/- 0.5 cm, respectively, were randomly divided into 18 groups of 4 fish each. Water temperature was 28 degrees C. Triplicate groups received one of two levels of dietary protein (15 and 30% as fed basis) and one of 3 doses of rhGH (0, 2 and 4 mu g/g) via intraperitoneal injection twice a week for 6 weeks, using a randomized complete block design. Somatotropin was noted to stimulate linear and body weight gain. The higher protein level supported increased growth in weight and length, but there was no interaction between protein level and rhGH dose for either parameter. Protein efficiency ratio and percentage protein deposited showed higher values on diets containing 15% protein. Somatotropin treatment did not significantly affect body composition, but there was a trend towards improved protein retention and reduced carcass lipid. In conclusion, the results of this experiment suggest that rhGH is able to stimulate linear gain in tambacu.

Dietary macronutrients, endocrine functioning and intermediary metabolism in broiler chickens - Pair wise substitutions between protein, fat and carbohydrate

Three pens of male broiler chicks were raised under standard conditions and fed from 7 to 42 days of age three isocaloric diets each with 15.8; 19.6 and 19.5% of CP; and 51, 51, and 44% of CHO; and 6.5; 3.0 and 7.7% of fat, and designated as the low protein (LowCP), low lipid (LowL) and low carbohydrate (LowCHO) diets, respectively. Body weights and feed intake were monitored weekly and blood samples were collected at the same time for posterior analysis of hormone and metabolite content. Chickens fed the LowCP diet were characterized by a reduced body weight gain and feed intake and poorer feed conversion efficiency compared to those fed the LowL and LowCHO diets, which were very similar in this respect. Plasma corticosterone and glucose levels and creatine kinase activity were not significantly changed by diet composition. LowCP chickens were characterised by the lowest plasma T-4 and uric acid levels (indicative for reduced protein breakdown and lower protein ingestion) but highest plasma triglyceride levels (congruent with their higher fat deposition) compared to the LowL and LowCHO chickens. LowL chickens had on average higher plasma T-3 and free fatty acid levels compared to the LowCP and LowCHO chickens.In conclusion, a limited substitution of carbohydrate for fat in iso-nitrogenous, iso-energetic diets has no pronounced effects on plasma hormone and metabolite levels, except for the elevation in T-3 (may enhance glucose uptake) and free fatty acid levels in the plasma of the chickens fed the LowL diet. The protein content of the diet has a greater impact on zootechnical performance, and underlying endocrine regulation of the intermediary metabolism compared to the dietary lipid and CHO fraction. (C) 2003 Elsevier B.V. All rights reserved.

EFFECTS OF DIETARY-PROTEIN, ANGIOTENSIN-I CONVERTING-ENZYME INHIBITION AND MESANGIAL OVERLOAD ON THE PROGRESSION OF ADRIAMYCIN-INDUCED NEPHROPATHY

Adriamycin, a commonly used antineoplastic antibiotic, induces glomerular lesions in rats, resulting in persistent proteinuria and glomerulosclerosis. We studied the effects of dietary protein and of an angiotensin I converting enzyme inhibitor on the progression of this nephropathy and the evolution of the histological lesions, as well as mesangial macromolecule flow. Adriamycin nephropathy was induced by injecting a single iv dose of adriamycin (3 mg/kg body weight) into the tail vein of male Wistar rats (weight, 180-200 g). In Experiment I animals with adriamycin-induced nephropathy were fed diets containing 6% (Low-Protein Diet Group = LPDG), 20% (Normal-Protein Diet Group = NPDG) and 40% (High-protein Diet Group = HPDG) protein and were observed for 30 weeks. In Experiment II the rats with adriamycin nephropathy were divided into 2 groups: ADR, that received adriamycin alone, and ADR-ENA, that received adriamycin plus enalapril, an angiotensin I converting enzyme inhibitor. The animals were sacrificed after a 24-week observation period. Six hours before sacrifice the animals were injected with I-131-ferritin and the amount of I-131-ferritin in the glomeruli was measured. In Experiment III, renal histology was performed 4, 8 and 16 weeks after adriamycin injection. At the end of Experiment I the tubulointerstitial lesion index was 2 for LPDG, 8 for NPDG, and 7.5 for HPDG (P<0.05); the frequency of glomerulosclerosis was 19 +/- 6.1% in LPDG, 42.6 +/- 6% in NPDG, and 54 +/- 9% in HPDG (P<0.05); and proteinuria was 61.1 +/- 25 mg/24 h in LPDG, 218.7 +/- 27.5 mg/24 h in NPDG, and 324.5 +/- 64.8 mg/24 h in HPDG (P<0.05). In Experiment II, at sacrifice, 24-h proteinuria was 189 +/- 16.1 mg in ADR, and 216 +/- 26.1 mg in ADR-ENA (P>0.05); the tubulointerstitial lesion index was 5 for ADR, and 5 for ADR-ENA (P>0.05); the frequency of glomerulosclerosis was 40 +/- 5.2% in ADR and 44 +/- 6% in ADR-ENA (P>0.05); the amount of I-131-ferritin in the mesangium was 214.26 +/- 22.71 cpm/mg protein in ADR and 253.77 +/- 69.72 cpm/mg protein in ADR-ENA (P>0.05). In Experiment III, sequential histological analysis revealed an acute tubulointerstitial cellular infiltrate at week 4, which was decreased at week 8. Tubular casts and dilatation were first seen at week 8 and increased at week 16 when few glomerular lesions were found. The results suggest that the tubulointerstitial lesions may play a role in the development of glomerulosclerosis in adriamycin-induced nephropathy.

HIGH DIETARY CARBOHYDRATE AND PANCREATIC LESION

The ability of high dietary carbohydrate to induce acute pancreatitis was investigated in groups of 16,2 1-day and 15-month old rats fed different carbohydrate diets for 30 days. Significantly increased levels of serum amylase (2-fold), phospholipids (50%),phosphorus (2-fold), and lipoperoxides (8-fold) were observed in 15-month old rats fed a high-carbohydrate diet, compared to rats fed a diet with normal carbohydrate levels, indicating peroxidation of membrane lipids which caused final cell death and pancreatic lesion. Serum Cu-Zn superoxide dismutase activity was not altered. Daily administration of bovine Cu-Zn superoxide dismutase conjugated with polyediylene glycol prevented the serum level alterations and pancreatic lesions, indicating that the superoxide radical has a role in dietary carbohydrate-induced acute pancreatitis. No biochemical changes were observed in rats in which treatment was initiated on the 21st day of life indicating that this is an age-related lesion.

Dietary vitamin or mineral mix removal during the finisher period on broiler chicken performance

The effect of dietary vitamin (VS) and mineral (MS) mix withdrawal between 42 and 49 d of age on broiler chicken performance was evaluated. The diets were formulated based on corn and soybean meal, and the experiments were conducted in floor pens using wood shavings as litter. Trial I evaluated withdrawal of VS and MS mix at 42, 45, and 49 d. The results of this trial showed that VS and MS mix withdrawal at 42 d of age did not impair feed intake (FI) or weight gain (WG), but feed conversion (FC) was improved (P = 0.043) when both mixes were maintained in the diets until 49 d of age. Trial 2 assessed the withdrawal of VS or MS mix at 42 d of age. FI and WG were not affected by withdrawal, but FC was poorer (P = 0.035) for the broilers fed the diet without VS. The relative liver weight was reduced by VS or MS mix withdrawal (P = 0.014 and P = 0.001, respectively). Carcass, breast, and leg yields were not affected by VS or MS mix withdrawals in either trial. The findings of the study suggested that VS mix withdrawal during the final period of broiler chicken growth was more deleterious than the withdrawal of MS mix, because it affected FC ratio. VS or MS withdrawal during this period did not affect carcass yield.

Effects of dietary macronutrient content on energy metabolism and uncoupling protein mRNA expression in broiler chickens

The objective of the present study was to investigate the effects of dietary macronutrient ratio on energy metabolism and on skeletal muscle mRNA expression of avian uncoupling protein (UCP), thought to be implicated in thermogenesis in birds. Broiler chickens from 2 to 6 weeks of age received one of three isoenergetic diets containing different macronutrient ratios (low-lipid (LL) 30 v. 77 g lipid/kg-, low-protein (LP) 125 v. 197 g crude protein (N X 6.25)/kg; low-carbohydrate (LC) 440 v. 520 g carbohydrate/kg). LP chickens were characterised by significantly lower body weights and food intakes compared with LL and LC chickens (-47 and -38% respectively) but similar heat production/kg metabolic body weight, as measured by indirect calorimetry, in the three groups. However, heat production/g food ingested was higher in animals receiving the LP diet (+41%, P<0.05). These chickens also deposited 57% less energy as protein (P<0.05) and 33% more as fat. No significant differences in energy and N balances were detected between LL and LC chickens. The diets with the higher fat contents (i.e. The LP and LC diets) induced slightly but significantly higher relative expressions of avian UCP mRNA in gastrocnemius muscle, measured by reverse transcription-polymerase chain reaction, than the LL diet (88 and 90 v. 78% glyceraldehyde-3-phosphate dehydrogenase respectively, P<0.05). Our present results are consistent with the recent view that UCP homologues could be involved in the regulation of lipid utilisation as fuel substrate and provide evidence that the macronutrient content of the diet regulates energy metabolism and especially protein and fat deposition.

Dietary macronutrients and performance and plasma hormone and metabolite levels of broiler chickens fat by carbohydrate substitution

The present experiment was aimed to study the effects of an isocaloric substitution of fat by carbohydrate calories while maintaining the same CP content - on some endocrine parameters and key metabolites of the lipid (L), protein (CP) and carbohydrate (CHO) metabolism and muscle cell membrane integrity of broiler chickens. Ninety male broiler chicks (Cobb) were obtained at 1-day old and raised in an environmentally controlled room. Food and water was provided ad libitum. At day 7, the chicks were provided with the experimental diets: Control diet (CON: 20% CP; 9.1% L; 39.6% CHO), Low lipid diet (LowL: 22% CP; 3.36% L; 59.7% CHO), and low carbohydrate diet (LowCHO: 22% CP; 8.09% L; 46.7% CHO). T e chickens fed the CON manifested the best growth rate feed conversion compared to both other groups. The CO chickens showed the highest plasma T-3 Concentrations at 14 days of age as compared to both LowL and LowCHO chickens. At 35 days of age however, LowL chickens were characterized by the highest plasma T-3 levels. Overall, CON birds had the highest plasma T-4 levels (P < 0.0001) compared to LowL and LowCHO chickens. Plasma corticosterone levels were not affected by diet composition. Glucose levels increased towards the end of the experimental period, but there was no overall effect of diet composition on plasma glucose levels. Chickens fed the CON diet were consistently characterized by the highest plasma uric acid levels compared to LowL and LowCHO chickens. Irrespectively of diet, plasma triglyceride levels were high at 14 days of age, then decreased and finally increased again during the last week. This latter increase was most pronounced for the CON chickens and is congruous with their high fat deposition. At 28 days of age, a significant effect of diet was observed, as CON birds had lower plasma free fatty acid (FFA) levels compared to LowL but not to LowCHO chickens. However there was no overall effect of diet composition on plasma FFA levels. Creatine kinase (CK) activities increased significantly with age and were consistently higher in CON chickens. In conclusion, fast growth in broiler chickens is positively correlated with catabolism of protein from dietary or endogenous origin and (muscle) cell membrane disruption as reflected in high plasma uric acid levels and CK activity, respectively. The currently investigated substitution of fat by CHO had no marked effects on endocrine functioning and intermediary metabolism, but this does not exclude that larger substitutions between both nutrients can have an effect.