RESUMEN
Parathyroid hormone-related protein (PTHrP), which causes hypercalcemia associated with malignant tumors, is known to be present in milk. Gene expression of PTHrP in the mammary gland increases markedly during parturition and with the onset of lactation. Even when circulating PTHrP levels are extremely low or below the detection limit, milk PTHrP levels are remarkably high. Parathyroid hormone-related protein derived from the mammary gland is assumed to play a role in maintaining the maternal calcium homeostasis and calcium transport from blood to milk. In previous studies that determined the PTHrP concentrations in milk, the pretreatments and diluent composition were not standardized. Here, we investigated the effect of various pretreatment procedures and diluent constitutions and the consequent PTHrP concentrations in commercial milk and milk products in Japan. Significant differences were found in PTHrP concentrations in raw milk samples subjected to different combinations of pretreatments (mixing, centrifugation, acidification, and heating) and diluents (0pM standard solution of PTHrP, plasma treated with protease inhibitors, and original diluent). We measured the PTHrP concentrations in normal liquid milk, processed milk, milk drinks, formulated milk powders, and skim milk powder by using the appropriate combination of pretreatment (acidification) and diluent (plasma treated with protease inhibitors). The PTHrP concentration in normal liquid milk, processed milk, and skim milk powder was as high as that in raw milk (>5nM), whereas that in milk drinks differed considerably. The PTHrP concentration in infant formulas (<2nM) was lower than that in the other milk products. These results indicate that a certain amount of PTHrP is ingested when milk and milk products are consumed.
Asunto(s)
Tecnología de Alimentos/métodos , Leche/química , Proteína Relacionada con la Hormona Paratiroidea/análisis , Animales , Calor , Humanos , Técnicas de Dilución del Indicador , Fórmulas Infantiles/química , Recién Nacido , JapónRESUMEN
Two main trials and three preliminary experiments were conducted in order to examine adverse effects of excess lysine in 140- to 150-kg Holstein bull calves. The animals had been trained to maintain reflex closure of the reticular groove after weaning and were fed a corn and soybean meal diet. In Trial 1 (n = 30), administration via the reticular groove of 0 to 64 g/d of lysine as L-lysine monohydrochloride resulted in a linear decrease in DMI and N utilization efficiency, with notably lower values at 64 g/d, although ADG and gain/feed ratio were not affected. Plasma arginine and ornithine did not decrease but rather increased over that range. Free lysine but not free arginine was detected in urine. In addition, free ornithine was excreted into urine only when 64 g/d was administered. Unexpectedly, severe but transient diarrhea occurred when 64 g/d of lysine were administered. Preliminary experiments revealed that a single administration of more than 32 g of lysine as L-lysine monohydrochloride could result in diarrhea, and the diarrhea was proven to be due to the lysine itself and not to the HCl portion. In Trial 2 (n = 15), a single administration of 40 or 60 g of lysine as L-lysine monohydrochloride resulted in increased fecal excretion of free lysine and ornithine, especially the latter, although free arginine was not detected in feces. These results suggested that diarrhea could occur almost concurrently with an imbalance in calves when 64 g/d of lysine was administered. However, lysine did not antagonize arginine at that level or at lower levels. The remarkable increase in fecal ornithine may be somehow related to the development of diarrhea from excess lysine.
Asunto(s)
Bovinos/crecimiento & desarrollo , Dieta/veterinaria , Lisina/efectos adversos , Animales , Arginina/sangre , Enfermedades de los Bovinos/inducido químicamente , Diarrea/inducido químicamente , Diarrea/veterinaria , Lisina/administración & dosificación , Masculino , Ornitina/sangreRESUMEN
Feeding dry foods supplemented with urine acidifier (D,L-methionine (Met) or ammonium chloride) decreased urinary pH and struvite activity product in clinically normal cats. As a result, the number of struvite crystals in urine was greatly reduced. Supplementation with 3% Met but not 1% Met caused decrease in the urinary concentration of sediment, which resulted from a reduction in the HCl-soluble fraction. The concentration of HCl-insoluble sediment was not affected by supplementation with the urine acidifier.
Asunto(s)
Cloruro de Amonio/administración & dosificación , Gatos/orina , Compuestos de Magnesio/orina , Metionina/administración & dosificación , Fosfatos/orina , Alimentación Animal , Animales , Enfermedades de los Gatos/prevención & control , Enfermedades de los Gatos/orina , Estudios Cruzados , Suplementos Dietéticos , Femenino , Concentración de Iones de Hidrógeno , Masculino , Estruvita , Cálculos Urinarios/prevención & control , Cálculos Urinarios/veterinariaRESUMEN
To compare the effects of two dietary protein sources, fish meal (FM) and corn gluten meal (CGM), fecal moisture content, nitrogen balance and urinary excretion were examined in adult cats. The dietary protein source did not cause a significant difference in daily food intake, water intake, urine volume, dry matter digestibility or urinary nitrogen excretion, but fecal moisture content was lower (P<0.02) in the CGM group. The HCl-insoluble fraction of urinary sediment tended to be higher in the CGM group (P<0.10), although urinary pH was similar in the two groups. These results suggest that CGM is comparable with FM in respect to nutritional value and the urine acidifying effect, but FM may be preferable to CGM for the prevention of constipation and struvite urolithiasis in cats.
Asunto(s)
Alimentación Animal , Gatos/metabolismo , Proteínas en la Dieta/metabolismo , Productos Pesqueros , Animales , Estudios Cruzados , Proteínas en la Dieta/farmacología , Ingestión de Líquidos , Ingestión de Alimentos , Heces/química , Femenino , Glútenes/metabolismo , Masculino , Orina/química , Orina/fisiología , Zea mays/metabolismoRESUMEN
The occurrence of methionine imbalance and toxicity was examined using 70- and 100-kg Holstein bull calves. The animals had been trained to maintain reflex closure of the reticular groove after weaning at 5 wk of age, and Trials 1 (n = 30) and 2 (n = 24) were conducted on animals at 7 and 12 wk of age, respectively. Calves received a corn-soybean meal diet in Trial 1 and a corn-corn gluten meal diet in Trial 2. In Trial 1, postruminal administration of 6 g of DL-methionine/d increased ADG, feed intake, gain/feed, and N retention compared with a control group receiving N-free supplement. However, the administration of 12 g of DL-methionine/d did not improve these variables, whereas both 18 and 24 g/d resulted in BW loss and decreased gain/feed and N utilization efficiency. In Trial 2, postruminal administration of 16 g/d of L-lysine from L-lysine monohydrochloride increased ADG, gain/feed, and N utilization efficiency compared with a control group receiving a N-free supplement. The administration of 8 g of DL-methionine/d in addition to L-lysine did not exert an adverse effect on these variables. However, the additional supplementation of 16 and 24 g of DLmethionine/d negated the improvement, whereas 32 g/d resulted in BW loss and decreased gain/feed and N utilization efficiency. These results showed that a methionine imbalance and toxicity occurred in calves with even a modest excess of DL-methionine, and 70-kg calves were more susceptible to methionine toxicity than 100-kg calves. Plasma concentrations of branched-chain amino acids and phenylalanine linearly decreased with increasing amounts of additional DL-methionine from 0 to 32 g/d in Trial 2. However, such a decrease occurred mainly within the range from 0 to 12 g/d in Trial 1. This decrease was suggested to occur in relation to methionine metabolism via the transsulfuration pathway.
Asunto(s)
Alimentación Animal , Bovinos/metabolismo , Metionina/toxicidad , Aminoácidos/sangre , Animales , Peso Corporal , Bovinos/sangre , Proteínas en la Dieta/administración & dosificación , Proteínas en la Dieta/farmacología , Suplementos Dietéticos , Homeostasis , Masculino , Glycine maxRESUMEN
Plasma osmolality estimated from plasma concentrations of Na+, Cl-, K+, glucose, and urea was compared with measured osmolality in preweaned Holstein calves. When calves (n = 5) were fed only milk replacer after fasting for 24 h, measured osmolality fluctuated almost in parallel with estimated osmolality during the 8-h period after feeding, although estimated values were about 90% of measured values. When calves (n = 5) were fed only calf starter after fasting for more than 16 h, measured osmolality did not parallel the estimated osmolality during the 8-h period after feeding. Some factors depressed measured osmolality in the first 2 h.
Asunto(s)
Glucemia/análisis , Bovinos/sangre , Electrólitos/sangre , Urea/sangre , Alimentación Animal/análisis , Animales , Cloruros/análisis , Cloruros/sangre , Japón , Masculino , Concentración Osmolar , Potasio/análisis , Potasio/sangre , Valores de Referencia , Sodio/análisis , Sodio/sangre , Factores de TiempoRESUMEN
Holstein bull calves were used to examine factors affecting water balance and fecal moisture content in suckling calves given dry feed for 2 wk from 1 wk of age. In Experiment 1 (n = 16), the shift of water balance (decreased urine volume, and increased water retention and fecal water excretion) and elevation of fecal moisture content were greatest when calf starter and Sudangrass hay were fed in addition to liquid milk replacer, compared with calves receiving only milk replacer. Intermediate changes occurred when calves were fed milk replacer and calf starter or milk replacer, calf starter, and rice straw. Water retention was correlated positively with digestible DMI and negatively with urine volume. Fecal water excretion was highly correlated with fecal DM excretion. In Experiment 2 (n = 18), water balance and fecal moisture content during wk 2 were affected by free access to calf starter and hay from wk 1. Urine volume of calves fed dry feed and milk replacer was lower than that of calves fed only milk replacer; however, when water was available in addition to dry feed, urine volume was similar to that of calves fed only milk replacer. Fecal water excretion was highly correlated with water retention rather than with fecal DM excretion, suggesting a close relationship to extracellular fluid volume. Ruminal fermentation would be an important factor affecting both water balance and fecal moisture content in suckling calves given dry feed.
Asunto(s)
Alimentación Animal , Animales Lactantes , Agua Corporal/metabolismo , Bovinos/metabolismo , Heces , Animales , Dieta , Fermentación , Masculino , Concentración Osmolar , Rumen/metabolismo , Orina , Aumento de PesoRESUMEN
Adverse effects of excess methionine were examined using 12 Holstein bull calves trained to maintain reflex closure of the reticular groove even after weaning at 5 wk of age. Two nitrogen balance experiments were conducted for 2 wk each from 6 wk (Stage 1; BW = 62 kg) and 12 wk of age (Stage 2; BW = 103 kg) by dividing the calves into three groups at each stage. Calves were fed a corn-soybean meal diet at 62 g/kg of metabolic BW at both stages. At Stage 1, feed efficiency (gain:feed intake) and nitrogen retention did not differ between the group supplemented with .333 g of DL-methionine and .111 g of L-lysine monohydrochloride/kg BW per day and the group supplemented with isonitrogenous diammonium citrate, although the level of DL-methionine was considered to be enough to induce toxicity. Conversely, administration of isonitrogenous casein increased nitrogen retention. At Stage 2, administration of the same levels of methionine and lysine resulted in reduced feed intake, depressed nitrogen retention, and BW loss. Conversely, administration of the isonitrogenous casein did not increase nitrogen retention compared with the supplement of isonitrogenous diammonium citrate. Administration of excess methionine and lysine increased plasma methionine concentrations up to 230 (Stage 1) or 190 micromol/dL (Stage 2). Plasma lysine concentrations were less than 24 micromol/dL at every stage. Administration of the amino acid mixture decreased plasma concentrations of branched-chain amino acids and phenylalanine more obviously at Stage 2 than at Stage 1. These results indicated that abomasal administration of .333 g of DL-methionine/kg BW per day induced methionine toxicity at Stage 2 but methionine imbalance at Stage 1.
Asunto(s)
Peso Corporal/efectos de los fármacos , Bovinos/crecimiento & desarrollo , Metionina/efectos adversos , Animales , Suplementos Dietéticos , Masculino , Metionina/administración & dosificación , Nitrógeno/administración & dosificación , ReflejoRESUMEN
We conducted three nitrogen balance trials using Holstein bull calves older than 16 wk (Trial 1; n = 8), 13 wk (Trial 2; n = 6), and 15 wk of age (Trial 3; n = 9) in a 4 x 4 (Trial 1) or 3 x 3 Latin square design (Trials 2 and 3) to identify limiting amino acids for a corn and soybean meal diet. All calves were trained to maintain reflex closure of the reticular groove after weaning at 5 wk of age. The basal diet was fed daily at 20 or 27 g/kg BW (Trial 1) and at 20 g/kg BW (Trials 2 and 3). The lower feeding level resulted in reduced urinary excretion of purine derivatives, suggesting reduced synthesis of ruminal microbial protein (Trial 1). In Trials 1 and 2, administration of DL-methionine plus L-lysine monohydrochloride through the reticular groove did not increase N retention compared with the supplement of isonitrogenous L-glutamine at either level of intake. In Trial 3, administration of either casein or isonitrogenous monosodium glutamate increased N retention to a similar extent above that observed with a N-free supplement. Results suggested that no specific amino acids were limiting for the corn-soybean meal diet. Administration of methionine plus lysine resulted in a remarkable increase in plasma methionine (Trials 1 and 2), especially at the lower intake level (Trial 1), and a decrease in plasma branched-chain amino acids at either intake level. Glutamine supplementation did not increase plasma branched-chain amino acids compared with the supplementation of diammonium citrate (Trial 2).
Asunto(s)
Alimentación Animal , Bovinos/crecimiento & desarrollo , Glycine max/química , Lisina/análisis , Metionina/análisis , Zea mays/química , Animales , Masculino , Factores de TiempoRESUMEN
Holstein bull calves were used to examine the effect of dry feed on water balance and fecal moisture content during the suckling period. In Experiment 1 (n = 20 calves), free access to concentrate and timothy hay decreased urine volume and increased apparent water retention, fecal water excretion, and fecal moisture content by 2 wk, although daily amounts of milk replacer also affected water balance when DMI from dry feed was low. In Experiment 2 (n = 20 calves), free access to concentrate and hay from wk 1 increased reabsorption of water from renal tubules during wk 2, resulting in reduced urine volume and increased plasma volume. In Experiment 3 (n = 10 calves), supplementation of 500 g/d of milk replacer plus free access to concentrate and hay from wk 1 increased plasma antidiuretic hormone by 2 wk compared with the concentration in calves receiving 200 g/d of milk replacer alone. Plasma antidiuretic hormone concentrations were highly correlated with plasma concentrations of acetate and ketone bodies but not with glucose and urea. In Experiment 4 (n = 16 calves), apparent water retention and fecal moisture content during wk 2 were increased by free access to concentrate from wk 1 but were not affected by rice straw as an inert bulk source.
Asunto(s)
Alimentación Animal , Agua Corporal , Bovinos/fisiología , Heces/química , Equilibrio Hidroelectrolítico , Ácido Acético/sangre , Animales , Animales Lactantes , Sangre , Nitrógeno de la Urea Sanguínea , Peso Corporal , Cuerpos Cetónicos/sangre , Masculino , Leche , Concentración Osmolar , Orina , Vasopresinas/sangre , Agua , Aumento de PesoRESUMEN
Five male cats were used to examine utilization of nitrogen and macro-minerals (calcium, phosphorus and magnesium) in response to food restriction and subsequent repletion. For the first week, each cat was daily given 135 g of dry cat food (baseline period), followed by a restriction period for 1 week; during this period, daily food was individually restricted to 40% of the amount consumed by each cat during the baseline period. Food provision was then returned to the daily 135 g for the final week (recovery period). Fecal weight changed in association with changes in daily food intake, but urine volume changed less with the periods. Fecal and urinary excretion of nitrogen rapidly decreased during the restriction period, but the decreases were smaller than the decrease in nitrogen intake, leading to net nitrogen loss. On the other hand, the food restriction had relatively smaller effects on retention of macro-minerals, and calcium retention was not significantly affected by daily food provision, although the plasma concentration of magnesium was increased during the restriction period and tended to return during the recovery period. Nitrogen retention was increased by the removal of food restriction, but did not exceed the original level of nitrogen retention during the baseline period. These findings suggested that restriction of diet had a serious effect on nitrogen balance, and the impaired protein nutrition might not be easily recovered by subsequent nutritional repletion.
Asunto(s)
Calcio/metabolismo , Gatos/metabolismo , Magnesio/metabolismo , Nitrógeno/metabolismo , Estado Nutricional/fisiología , Fósforo/metabolismo , Animales , Proteínas en la Dieta/metabolismo , Privación de Alimentos , MasculinoRESUMEN
Holstein bull calves (n = 51) weaned at 6 wk of age were used in four N balance trials for 4 wk (Trials 1 to 3) or for 2 wk (Trial 4) from 8 wk of age to identify limiting amino acids for a corn and soybean meal diet. The calves were trained to maintain reflex closure of the reticular groove throughout the trials. In Trial 1, administration of .111 g of DL-methionine plus .333 g of L-lysine monohydrochloride/kg BW through the reticular groove increased N retention compared with the control that received isonitrogenous L-glutamine, but administration of .333 g L-lysine monohydrochloride/kg BW alone did not increase N retention in Trial 2. In Trial 3, administration of .111 g of DL-methionine/kg BW improved N balance compared with the control, although the improvement was not detected when DL-methionine was restricted to .022 g/kg BW. In Trial 4, administration of the mixture of .111 g of DL-methionine, .333 g of L-lysine monohydrochloride, and .055 g of L-tryptophan/kg BW increased N retention in calves compared with calves that received an isonitrogenous mixture of .111 g of DL-methionine and .274 g of L-glutamine/kg BW, or .111 g of DL-methionine, .055 g of L-tryptophan, and .234 g of L-glutamine/kg BW. The present results suggest that methionine was the first-limiting and that lysine was probably the second-limiting amino acid for the corn and soybean meal diet in weaned calves less than 11 wk of age, although tryptophan may be either co-limiting with lysine or third-limiting.
Asunto(s)
Aminoácidos/metabolismo , Alimentación Animal , Fenómenos Fisiológicos Nutricionales de los Animales , Digestión/fisiología , Glycine max , Zea mays , Aminoácidos/administración & dosificación , Animales , Peso Corporal , Bovinos , Heces , Alimentos Fortificados , Masculino , Nitrógeno/metabolismo , Oryza , Factores de Tiempo , DesteteRESUMEN
Duodenal flow of microbial N (MN) was estimated from urinary purine derivatives to examine age-related changes in MN in male Holstein calves. In Exp. 1, endogenous purine derivatives were determined by measurement of purine derivatives in five calves fed nucleic acid-free milk replacer alone. In Exp. 2, the ratio of urinary excretion as purine derivatives to purines administered via the reticular groove was determined in three calves weaned at 5 wk of age. As a result, endogenous purine derivatives were constant at 705 mumol/(kg BW.75.d), irrespective of the amount of milk replacer, and the ratios of purine derivatives to duodenal purines were estimated to be .549, .276, .363, and .466 at wk 1, 6, 11, and 20 after weaning, respectively. Using these variables and urinary purine derivatives, the duodenal flow of MN was estimated and its relation with N balance was examined in 15 calves weaned at 5 wk of age in Exp. 3. Digestible OM was lower at wk 1 after weaning and transiently higher at wk 6. The percentage of N absorbed to N intake, N absorbed, N retained, and estimated duodenal MN were also lower at wk 1, and rapidly increased for the first 6 wk. These findings suggest that the increases in N absorbed and N retained for the first 6 wk after weaning were due to augmentation of duodenal flow of MN and dietary N that escaped ruminal degradation.
Asunto(s)
Envejecimiento/metabolismo , Bovinos/metabolismo , Duodeno/metabolismo , Nitrógeno/metabolismo , Purinas/orina , Destete , Envejecimiento/fisiología , Alantoína/orina , Animales , Peso Corporal/fisiología , Bovinos/fisiología , Bovinos/orina , Digestión/fisiología , Duodeno/microbiología , Ingestión de Alimentos/fisiología , Masculino , Rumen/metabolismo , Ácido Úrico/orinaRESUMEN
Holstein bull calves (n = 36) weaned at 6 wk of age were used in six trials to examine the response of N balance to postruminal administration of lysine with or without methionine in postweaned calves receiving diets based on corn and corn gluten meal. Calves were younger than 3 mo of age in Trials 1 and 2 but older than 3 mo in Trials 4 to 6. L-Lysine monohydrochloride was supplemented with or without DL-methionine twice daily through the reticular groove, except in Trial 4, in which N supplements were infused through duodenal cannulas. L-Glutamine was used as a nonspecific N source in every trial, and casein was a positive control in Trials 4 and 5. When daily CP intake from the diet was 3.9 g/kg BW, lysine was limiting for calves less than 11 wk of age (Trials 1 and 2) but not limiting for calves greater than 12 wk of age (Trial 3). No amino acid seemed to be limiting for calves greater than 20 wk of age (Trial 4) when daily CP intake was 4.1 g/kg BW, but lysine was limiting when CP intake was restricted to 3.0 g/kg BW when calves were more than 17 wk of age (Trial 5). However, lysine was not limiting above 18 wk of age (Trial 6) when CP intake was increased to 3.8 g/kg BW by adding urea to the diet. Results suggest that lysine may be limiting for corn and corn gluten meal diets only when ruminal microbial protein synthesis is restricted.
Asunto(s)
Enfermedades de los Bovinos/etiología , Enfermedades Carenciales/veterinaria , Dieta/veterinaria , Glútenes/metabolismo , Lisina/deficiencia , Zea mays/metabolismo , Envejecimiento/metabolismo , Análisis de Varianza , Animales , Arginina/sangre , Caseínas/análisis , Caseínas/metabolismo , Caseínas/farmacología , Bovinos , Enfermedades de los Bovinos/epidemiología , Cisteína/sangre , Enfermedades Carenciales/epidemiología , Enfermedades Carenciales/etiología , Glutamina/análisis , Glutamina/metabolismo , Glutamina/farmacología , Glútenes/química , Glicina/sangre , Lisina/análisis , Lisina/metabolismo , Masculino , Metionina/análisis , Metionina/metabolismo , Metionina/farmacología , Nitrógeno/metabolismo , Rumen/microbiología , Serina/sangre , Treonina/sangre , Zea mays/químicaRESUMEN
OBJECTIVE: To examine effects of high-protein diets (> 50% crude protein of dry matter) on urinary mineral excretion and struvite activity product ([Mg2+] x [NH4+] x [PO(4)3-]). ANIMALS: 14 clinically normal cats, 4 adult female and male cats for experiments 1 and 2, respectively, and 6 female kittens aged 4 months for experiment 3. PROCEDURE: Relations between dietary protein amount (25.9, 38.3, 51.4, and 65.4% crude protein [dry matter]) and urinary excretion of Mg, P, and Ca were examined in a 4 x 4-Latin square design (experiment 1). Struvite activity product, the index of solubility of struvite crystals, was determined when a high-protein diet (54.9%) was fed (experiment 2). Utilization of minerals in cats fed a high-protein diet long term was examined (experiment 3). RESULTS: Water intake and urine volume increased with increasing dietary protein concentration. Urinary Mg2+ excretion was not affected (experiment 1) or was decreased (experiment 3) by higher protein intake, leading to lower urine Mg2+ concentration in groups fed higher protein amounts. Urine pH was decreased by high-protein intake. As a result, PO(4)3- concentration was decreased by high-protein intake (experiment 2), although total daily urinary excretion of P was increased. Consequently, struvite activity product tended to decrease in cats fed high-protein diets, indicating increase in struvite solubility. High-protein intake decreased Ca and P retention by increasing their fecal and urinary excretions, respectively. CONCLUSION: As a consequence of the increase in urine volume and urine acidification, high-protein diets have potential ability to increase solubility of struvite crystals.
Asunto(s)
Proteínas en la Dieta , Compuestos de Magnesio/orina , Minerales/orina , Fosfatos/orina , Animales , Peso Corporal , Calcio/metabolismo , Gatos , Dieta , Diuresis , Femenino , Concentración de Iones de Hidrógeno , Magnesio/metabolismo , Masculino , Fósforo/metabolismo , Análisis de Regresión , EstruvitaRESUMEN
Our previous study revealed that weaning of calves aged 5 wk (early weaning) resulted in transient nutritional restriction with subsequent repletion. The present study was conducted to examine age-related changes in nitrogen balance, bone growth and myofibrillar protein degradation after early weaning in calves. At weaning, calves used in Experiment 2 had more severe nutritional restriction than those used in Experiment 1 due to a shorter duration of the suckling period (3 vs. 4 wk), a lesser amount of daily milk replacer (500 vs. 600 g) and a shorter period when given solid feed (for the last week vs. throughout the suckling period). In both experiments, nitrogen and calcium retentions were lower at weaning and transiently increased at 6 wk after weaning. However, detrimental effects on nitrogen and calcium retention immediately after weaning were more evident, and compensatory increases of nitrogen and calcium retention after weaning were more pronounced and continuous in Experiment 2 than in Experiment 1. The changes in plasma intact osteocalcin concentrations and urinary hydroxyproline excretion after weaning were similar to those for nitrogen and calcium retention in Experiment 2, whereas fractional degradation rate of myofibrillar protein was constant throughout the study in both experiments. These results suggest that the extent of nutritional restriction at weaning affects subsequent enhanced utilization of nitrogen and calcium, and that age-related changes in nitrogen retention after early weaning partly reflect changes in bone growth regulated by both forming and resorbing activities, independent of myofibrillar protein degradation.
Asunto(s)
Fenómenos Fisiológicos Nutricionales de los Animales , Desarrollo Óseo , Privación de Alimentos , Proteínas Musculares/metabolismo , Miofibrillas/metabolismo , Envejecimiento , Animales , Bovinos , Factor I del Crecimiento Similar a la Insulina/metabolismo , Masculino , Metilhistidinas/orina , Nitrógeno/metabolismoRESUMEN
Three experiments were conducted to examine the changes of N utilization after early weaning in calves. In Exp. 1, eight male Holstein calves were weaned at 5 wk of age and N balance was determined on the 1st, 6th, 11th, and 19th wk after weaning. In Exp. 2, to examine the effect of weaning age on N utilization, three calves were weaned at 5 wk of age and the other three at 11 wk of age. The N balance of both groups was determined on the same weeks of age (i.e., the 1st, 6th, 8th, and 11th wk after weaning in the earlier-weaned group). In Exp. 3, to examine the effect of a higher content of CP (17.9%) and TDN (75%) in concentrate on N utilization, three calves were weaned at 6 wk of age and the N balance was determined on the 1st, 5th, 10th, and 20th wk after weaning. The intake of concentrate was low in wk 1 but rapidly increased in the next 5 wk (1.74 and 1.72 times in Exp. 1 and 2, respectively). Nevertheless, the TDN intake tended to be lower in calves weaned early just after weaning compared with that in suckling calves in Exp. 2. The apparent N digestibility steadily increased with age and reached a plateau on wk 11 and 6 after weaning in Exp. 1 and 2, respectively. Conversely, the ratio of N retained:N absorbed tended to be high up to wk 6 after weaning and thereafter decreased, leading to a transient high N retained:N intake ratio on wk 6 after weaning.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Envejecimiento/metabolismo , Bovinos/metabolismo , Nitrógeno/metabolismo , Destete , Alimentación Animal , Animales , Proteínas en la Dieta/administración & dosificación , Digestión , Ingestión de Alimentos/fisiología , MasculinoRESUMEN
The concentrations of holotrichs, reducing sugars and fermentation end-products, and the fluid dilution rates, in the cranial (CR), ventral (V) and caudal (CA) regions of the reticulo-rumen of cows were compared. Additionally, holotrich numbers in fluid and solid digesta samples taken from the dorsal (D) region were determined at different time-intervals. Holotrich numbers expressed per ml fluid at site D were almost twofold those expressed per g solid digesta, and the fluctuation of their numbers in fluid preceded that in solid digesta. Holotrich concentrations at site CR were higher before feeding than after feeding, while those at sites V and CA were lower before feeding than for a few hours after feeding. At sites V and CA, holotrich concentrations fluctuated in good agreement with reducing sugar concentrations, but the increase in the former always preceded that in the latter. The concentration of volatile fatty acids (VFA) tended to decrease from site CA to site CR, while the dilution rate was highest in site CR. The results suggest that migration of holotrichs from the reticulum to the rumen and vice versa are the cause of fluctuation in their numbers, and also the mechanism by which they are retained in the rumen of cattle.
Asunto(s)
Bovinos/parasitología , Cilióforos/aislamiento & purificación , Rumen/parasitología , Amoníaco/análisis , Animales , Ácidos Grasos Volátiles/análisis , Femenino , Alimentos , Contenido Digestivo/análisis , Reticulum/parasitología , Factores de TiempoRESUMEN
Steady-state pharmacokinetics of valproic acid (VPA) with or without other antiepileptic drug (AED) treatment were studied in 37 children. Children (N = 16) receiving multiple AED therapy had a higher clearance (23.5 vs 13.0 ml/hr/kg, P less than 0.001), larger volume of distribution (0.30 vs 0.22 L/kg, P less than 0.01), and shorter half-life (9.4 vs 12.3 hours, P less than 0.01) than did those (n = 21) receiving VPA only. Inverse correlations of age with clearance (R = -0.559, P less than 0.01) and apparent volume of distribution of VPA (r = -0.490, P less than 0.05) were observed in children receiving monotherapy. In determining the dose and dosing interval of VPA, consider a possible alteration in the pharmacokinetics relating to age and other concurrent AED therapy.