Heat regulation during exercise with controlled cooling

During heavy sustained exercise, when sweating is usually needed to dissipate the extra metabolic heat, controlled cooling caused heat loss to match total heat production with little sweating. The total heat produced and metabolic rate were varied independently by having subjects walk uphill and down. Heat loss was measured directly with a suit calorimeter; other measurements included metabolic energy from respiratory gas exchange and body temperatures. Thermoregulatory sweating was minimized by adjusting cooling in the calorimeter suit. Heat loss rose to match total heat, not metabolic rate, and there was a slow rise in rectal temperature. In the absence of major thermoregulatory response rectal temperature correlated most closely with total heat; it also correlated with the relative oxygen cost of exercise. Heat flow or heat content appeared to be the controlled variable and body temperature rise a secondary event resulting from thermal transport lag.     

Effect of cold exposure on energy metabolism in the young pig

Twenty-four piglets were weaned at 3 weeks of age and received 615 kJ metabolizable energy/(kg body weight X day). The temperature was reduced from 29 to 25 degrees C by 4 weeks of age. Six pigs were exposed to cold by reducing the temperature to 10 degrees C by 5 weeks of age while the other six were exposed to 23 degrees C. These two temperatures were maintained for 3 weeks. Each week the three pigs closest to the mean weight of each group were used for measurements of heat production for 23 h by open-circuit calorimetry and glucose turnover by continuous infusion of [6-3H]- and [U-14C]-glucose. The animals were sacrificed at 8 weeks of age, a sample of their intercostal muscle was used for in vitro measurement of muscle respiration, and the carcass was analyzed. There was no change in heat production, glucose turnover, and rectal temperature during the 3 weeks of cold exposure, so the data were pooled. Cold exposure increased heat production by 50%, forced mobilization of fat reserves (1000 g over the 3 weeks), and increased glucose replacement rate by 20%. The decline in rectal temperature to 37.6 from 38.8 degrees C could be regarded as a strategy to reduce energy needed to regulate body temperature. In the cold, heat production equalled metabolizable energy intake, but protein deposition was maintained at the same level as that in the pigs at the thermoneutral temperature, using the energy derived from the mobilization of body fat. The increase in Na+-K+ ATPase dependent respiration accounted for 70% of the increase in O2 consumption of muscle from cold-exposed pigs and thus is potentially an important component of cold-induced thermogenesis in the pig.     

Low sanitary conditions increase energy expenditure for maintenance and decrease incremental protein efficiency in growing pigs

Requirements for energy and particular amino acids (AAs) are known to be influenced by the extent of immune system stimulation. Most studies on this topic use models for immune system stimulation mimicking clinical conditions. Extrapolation to conditions of chronic, low-grade immune system stimulation is difficult. We aimed to quantify differences in maintenance energy requirements and efficiency of energy and protein used for growth (incremental energy and protein efficiency) of pigs kept under low (LSC) or high sanitary conditions (HSC) that were fed either a basal diet or a diet with supplemented AA. Twenty-four groups of six 10-week-old female pigs were kept under either LSC or HSC conditions for 2 weeks and fed a diet supplemented or not with 20% extra methionine, threonine and tryptophan. In week 1, feed was available ad libitum. In week 2, feed supply was restricted to 70% of the realized feed intake (kJ/(kg BW)^0.6 per day) in week 1. After week 2, fasting heat production (FHP) was measured. Energy balances and incremental energy and protein efficiencies were measured and analyzed using a GLM. Low sanitary condition increased FHP of pigs by 55 kJ/(kg BW)^0.6 per day, regardless of diet. Low sanitary condition did not alter the response of faecal energy output to incremental gross energy (GE) intake, but it reduced the incremental response of metabolizable energy intake (12% units), heat production (6% units) and energy retained as protein (6% units) to GE intake, leaving energy retained as fat unaltered. Incremental protein efficiency was reduced in LSC pigs by 20% units. Incremental efficiencies for energy and protein were not affected by dietary AA supplementation. Chronic, low-grade immune stimulation by LSC treatment increases FHP in pigs. Under such conditions, the incremental efficiency of nitrogen utilization for body protein deposition is reduced, but the incremental efficiency of absorbed energy for energy or fat deposition is unaffected.     

Energy metabolism and nutrient oxidation in young pigs and rats during feeding, starvation and re-feeding

The investigation included individual measurements of energy metabolism and oxidation of nutrients in 12 castrated male pigs (Sus scrofa) (20-40 kg) and 12 male rats (Rattus norvegicus) (65-105 g). Measurements were carried out in 5-6 days balance periods with ad libitum feeding, followed by 3-4 days of starvation and 4 days of re-feeding. O2 consumption and CO2 production were measured by open-air-circuit respiration units. In the feeding period, protein retention in relation to metabolic live mass (kg(0.75)) was identical for pigs and rats, while there was a tendency of a higher fat retention in pigs than in rats. A substantial part of digested carbohydrate was not oxidized, but transferred to fat metabolism without significant differences (P > 0.05) between pigs and rats (18% vs. 22%). During starvation, nitrogen excretion in urine decreased to 226 mg/kg(0.75) in pigs and to 429 mg/kg(0.75) in rats, indicating a lower rate of body protein degradation in pigs. Heat production was reduced to 592 and 338 kJ/kg(0.75), while the contribution of heat from oxidation of protein (OXP), carbohydrate (OXCHO) and fat (OXF) showed the same pattern for pigs and rats during all periods. Heat production during feeding and re-feeding was covered by OXP+OXCHO with no OXF and reversibly after 2 days of starvation by OXP+OXF with no OXCHO. The rat may be a suitable model for pigs regarding general patterns of quantitative nutrient partition, but any direct application of results measured with rats to pigs shall be taken cautiously, keeping in mind that modern pigs have been selected for a high growth rate and protein deposition which has not been the case for the laboratory rat.     

Effects of fermentable starch and straw-enriched housing on energy partitioning of growing pigs

Both dietary fermentable carbohydrates and the availability of straw bedding potentially affect activity patterns and energy utilisation in pigs. The present study aimed to investigate the combined effects of straw bedding and fermentable carbohydrates (native potato starch) on energy partitioning in growing pigs. In a 2 × 2 factorial arrangement, 16 groups of 12 pigs (approximately 25 kg) were assigned to either barren housing or housing on straw bedding, and to native or pregelatinised potato starch included in the diet. Pigs were fed at approximately 2.5 times maintenance. Nitrogen and energy balances were measured per group during a 7-day experimental period, which was preceded by a 30-day adaptation period. Heat production and physical activity were measured during 9-min intervals. The availability of straw bedding increased both metabolisable energy (ME) intake and total heat production (P < 0.001). Housing conditions did not affect total energy retention, but pigs on straw bedding retained more energy as protein (P < 0.01) and less as fat (P < 0.05) than barren-housed pigs. Average daily gain (P < 0.001), ME intake (P < 0.001) and energy retention (P < 0.01) were lower in pigs on the native potato starch diet compared to those on the pregelatinised potato starch diet. Pigs on the pregelatinised potato starch diet showed larger fluctuations in heat production and respiration quotient over the 24-h cycle than pigs on the native potato starch diet, and a higher activity-related energy expenditure. The effect of dietary starch type on activity-related heat production depended, however, on housing type (P < 0.05). In barren housing, activity-related heat production was less affected by starch type (16.1% and 13.7% of total heat production on the pregelatinised and native potato starch diet, respectively) than in straw-enriched housing (21.1% and 15.0% of the total heat production on the pregelatinised and native potato starch diet, respectively). In conclusion, the present study shows that the availability both of straw bedding and of dietary starch type, fermentable or digestible, affects energy utilisation and physical activity of pigs. The effects of housing condition on protein and fat deposition suggest that environmental enrichment with long straw may result in leaner pigs. The lower energy expenditure on the physical activity of pigs on the native potato starch diet, which was the most obvious in straw-housed pigs, likely reflects a decrease in foraging behaviour related to a more gradual supply of energy from fermentation processes.     

Heat production and substrate oxidation in rats fed at maintenance level and during fasting

A total of 36 Wistar rats were fed a commercial diet to a stipulated live weight of 75 g (Group A), 100 g (Group B) and 225 g (Group C). All rats were measured in energy balance experiments, in which the animals were fed near maintenance level, followed by a period of fasting with measurements of the gas exchange. The rats in Group A, B and C were fasted for 2, 3 and 4 days, respectively. The minimum heat production on the last day of fasting for all groups was proportional to metabolic body weight (kg0.75) with a regression: heat production, kJ day-1 = 321 x kg0.75 (R2 = 0.994). In rats fed near maintenance level, heat production was provided by oxidation of carbohydrates in 80-85%, oxidation of protein was 10-15%, while oxidation of fat contributed less than 10%. It is suggested that in the fasting period, the contribution to the total heat production from oxidized carbohydrate and fat depended on the size of the fat depots, a large fat depot giving rise to fat oxidation. On the last day of fasting, 24, 51 and 90% of the total heat originated from fat oxidation in Group A, B and C, respectively.     

Use of microcalorimetric monitoring in establishing continuous energy balances and in continuous determinations of substrate and product concentrations of batch-grown Saccharomyces cerevisiae

Energy balance calculations were performed for different physiological states during batch growth of Saccharomyces cerevisiae with glucose as carbon and energy source. For the different physiological states, energy recoveries close to one were obtained, which permitted a continuous control that the constantly changing growth process was quantified accurately. During the respiro-fermantative phase of growth, during which glucose served as the carbon and energy source, a low-heat-yield value (DeltaQ(x)) of -8.6 kJ/g dry biomass formed was obtained. This low-heat-yield value was due to the mainly fermentative metabolism during the middle of this phase of growth. After a transition phase, the ethanol produced during the respiro-fermentative growth was respired. During this respiratory phase, the heat yield values increased markedly, resulting in a lowest value of -42.7 kJ/g. The low-heat-yield values of the respiro-fermentative growth is not a reflection of the most efficient metabolism of S. cerevisiae. On the contrary, during the middle of this phase, 74% of the energy input was dissipated as ethanol, 6% was dissipated as heat, and the energy conserved as biomass was just 13%, while during the early respiratory phase, 69% of the energy input was dissipated as heat, and 22% of the energy input was conserved as biomass. By mathematical modeling and direct monitoring on-line of the rate of heat production, continuous calculations of (1) glucose consumption, and (3) biomass production were performed, and were shown to correlate closely with measured values for the continuously changing growth process.     

Studies on energy metabolism of germinating wheat seeds

The amount of energy dissipated in the form of heat in the metabolic processes carried on during the initial period of the germination of wheat seeds was determined directy by means of an adiabatic microcalorimeter. The total energy simultaneously liberated in the respiration of the investigated seeds was calculated from the carbon-dioxide production. The proportion of total energy released in respiration to the amount of energy dissipated as heat indicates that about 5 per cent of respiratory energy is retained in the tissues of growing seedlings. The percentual rate of energy dissipated is not dependent on the temperature or the age of seedlings.     

Effects of feeding diets containing essential oils and betaine to heat-stressed growing-finishing pigs

This study was to evaluate the effects of dietary essential oils (EO) and betaine on growth performance, nutrient digestibility and serum hormones in growing-finishing pigs under heat stress conditions. A total of 96 crossed pigs [(Landrace × Yorkshire) × Duroc] with an initial body weight (BW) of 24.7 ± 0.27 kg were used in an 18-week trial. Pigs were randomly allocated to four treatments according to BW and gender. There were six replication pens in each treatment, with four pigs (two barrows and two gilts) per pen. Treatment groups were: (1) control group (CON), basal diet + 23°C for 24 h; (2) heat stress group (HC) with basal diet + 37°C for 9 h, 23°C for 15 h; (3) group HEO, HC with 0.01% EO; (4) group HBE, HC with 0.1% betaine. During the overall period, groups HEO and HBE had higher (p < 0.05) average daily gain than group HC. At week 6, group HC had a lower apparent total tract digestibility (ATTD) of dry matter (DM) (p < 0.05), but at week 12, this group had lower ATTD of DM, nitrogen and gross energy than group HEO (p < 0.05). At week 12 and 18, dietary EO decreased (p < 0.05) serum cortisol and norepinephrine concentration. At week 18, dietary EO and betaine decreased (p < 0.05) epinephrine concentration. Conclusively, dietary EO may be a potential nutritional strategy to alleviate heat stress in growing-finishing pigs.     

The effect of lysine intake on energy partitioning and utilization in growing pigs

An experiment utilizing 12 castrated male pigs within a body weight range of 23 - 147 kg was conducted to ascertain whether the alteration of protein quality by varying the level of lysine intake is influencing total energy retention, heat production and therewith efficiency of energy utilization for growth. The animals were allotted to two treatments of a constant medium (11.5 g/d) or high lysine intake (13.5 g/d) level on the basis of an isonitrogenous diet at an energy intake level of 1.3 MJ ME/kg BW0.75. Representing a tool for determining body composition, at target body weights of 35, 55, 80, 115 and 145 kg measurements of deuterium dilution space were undertaken. Protein and lipid accretion were calculated by difference, assuming accretion to contain 23.8 and 39.0 kJ/g, respectively. The results show a significant effect (p < 0.05) between treatment groups for the values of energy retained in protein, thus ensuring the intended alteration by protein quality. Furthermore total energy retention, heat production (difference between ME intake and energy retention) and therewith energy utilization demonstrate independence from the composition of body weight (BW) gain. These observations confirm earlier results, but however, seem to be in contrast to the supposition of a constant efficiency for protein (kp) and fat (kf) accretion, respectively. This may be attributed to a variable kp, in fact to a smaller kp at minor values for protein accretion due to an increased whole body protein turnover. Lacking evidence from experimental data for advantages in using constant values for kp and kf to determine the accurate energy requirement for growth, a uniform value for the efficiency of total energy retention seems to be more adequate.     

鼎湖山马尾松群落能量分配及其生产的动态

对鼎湖山马尾松群落各组分热值、能量现存量、能量净生产量及群落太阳能转化效率进行了研究。结果表明:(1)乔木层马尾松各器官热值相差不大,为19.02~20.30 kJ/g(总平均 19.34 kJ/g);灌木层植物热值低于乔木层,为16.55~18.78 kJ/g(总平均17.82 kJ/g);草本层植物热值低于灌木层,为13.07~16.16 kJ/g(总平均15.03 kJ/g)。(2)群落能量总现存量随时间而增加,且组分分配比例因年份不同而异。在 1990、1995和2000年分别为167 141.4、270 295.9和321 294.3 kJ/m2,其中乔木层占93.4%、79.8%和86.7%,林下层占3.5%、10.6%和7.2%,而地表现存凋落物层仅占3.2%、9.5%和6.1%。(3)群落在1990~1995年和1995~2000年期间能量净生产每年分别为 1 7083. 2 kJ/m2 和 21 571. 8 kJ/m2,其中乔木层占 96. 6%和95 5%,林下层仅占3.4%和5.0%。所有能量生产量中,群落自身增长能量(即年能量存留量)占 72.7%和57.6%,而释放到其它子系统的能量占27.3%和42.4%。(4)群落太阳能转化效率在 1990~1995 年和 1995~2001年分别为0.759%和0.958%,10年平均为0.873%。     

Influence of exercise on the immune function of rats of various ages

The purpose of this study was to determine whether exercise could prevent the age-related decline in mitogenesis, which has been well documented in rats, mice, and humans. At 1, 6, 12, and 18 mo of age, male Fischer F344 rats were subjected daily to swimming exercise for 6 mo. At the end of the 6-mo training period, spleen lymphocytes were isolated from the exercised rats and from age-matched sedentary controls. The induction of lymphocyte proliferation was measured with the mitogens concanavalin A (ConA) and lipopolysaccharide (LPS). In addition, the ability of the lymphocytes to produce interleukin 2 (IL 2) in response to ConA induction was measured. ConA- and LPS-induced proliferation decreased 41-63% between 7 and 25 mo of age in both exercised and sedentary control rats. ConA-induced IL 2 production decreased 42 and 62% between 7 and 25 mo of age for exercised and sedentary control rats, respectively. Although the age-related decline in mitogen-induced proliferation and IL 2 production was smaller in exercised rats, this was due to a lower level of mitogenesis and IL 2 production in lymphocytes from young exercised rats. Exercise resulted in a significant decrease (23-32%) in mitogen-induced lymphocyte proliferation and IL-2 production in 7-mo-old exercised rats compared with 7-mo-old sedentary rats. However, in the 18- and 24-mo-old rats, mitogen-induced lymphocyte proliferation and IL 2 production was not significantly different between exercised and sedentary control rats.     

Contribution of blood lactate to the energy expenditure of weight training

Bioenergetic interpretations of energy transfer specify that rapid anaerobic, substrate-level adenosine triphosphate (ATP) turnover with lactate production is not appropriately represented by an oxygen uptake measurement. Two types of weight training, 60% of 1 repetition maximum (1RM) with repetitions to exhaustion and 80% of 1RM with limited repetitions, were compared to determine if blood lactate measurements, as an estimate of rapid substrate-level ATP turnover, provide a significant contribution to the interpretation of total energy expenditure as compared with oxygen uptake methods alone. The measurement of total energy expenditure consisted of blood lactate, exercise oxygen uptake, and a modified excess postexercise oxygen consumption (EPOC); oxygen uptake-only measurements consisted of exercise oxygen uptake and EPOC. When data from male and female subjects were pooled, total energy expenditure was significantly higher for reps to exhaustion (arm curl, +27 kJ; bench press, +27 kJ; leg press, +38 kJ; p < 0.03) and limited reps (arm curl, +12 kJ; bench press, +23 kJ; leg press, + 24 kJ; p < 0.05) when a separate measure of blood lactate was part of the interpretation. When the data from men and women were analyzed separately, blood lactate often made a significant contribution to total energy expenditure for reps to exhaustion (endurance-type training), but this trend was not always statistically evident for the limited reps (strength-type training) protocol. It is suggested that the estimation of total energy expenditure for weight training is improved with the inclusion, rather than the omission, of an estimate of rapid anaerobic substrate-level ATP turnover.     

Meal size and frequency: effect on potentiation of the thermal effect of food by prior exercise

Prior exercise potentiates the thermic effect of a carbohydrate meal. The purpose of this study was to determine if meal size or feeding pattern influences this response. Two groups of healthy, normal-weight young women exercised for 45 min on a cycle ergometer at 70% of maximal aerobic capacity. Once aerobic capacity returned to pre-exercise baseline, the thermic effect of food (TEF) was determined by indirect calorimetry over a 2-h period. One group of subjects ingested a 2510-kJ meal and the other a 5020-kJ meal. As a control, subjects ingested the test meal without prior exercise. In addition, subjects ingesting the 5020–kJ meal were studied for an additional 2 h. In a separate trial, these subjects ingested a 5020-kJ meal in two equal portions after a bout of exercise, the second portion 120 min after the first. TEF was less for the 2510-kJ meal compared with the 5020-kJ meal for both the control [mean (SE), 76 (17) vs 158 (19) kJ · 2h^–1,P < 0.01), and prior exercise [124 (23) vs 197 (24) kJ · 2h^–1,P<0.01) trials. However, the same increment in TEF resulted from the prior bout of exercise [48 (9) vs 40 (8) kJ · 2h^– for 2510-and 5020-kJ meals, respectively). TEF was 31 % lower when the 5020-kJ meal was given in two portions compared with one [281 (30) vs 369 (41) kJ · 4h^–1, P < 0.05]. No difference in TEF was found between the first and second 2510-kJ portion. The results suggest that potentiation of TEF by prior exercise is not influenced by caloric density or energy content of the meal. Rather, meal volume and hence meal frequency is a greater determinant of postexercise TEF.     

Effect of a soy protein diet on protein and energy metabolism and organ development in protein-restricted growing pigs

Two feeding experiments were carried out with castrated male pigs weighing between 10 and 30 kg to study acute and persisting dietary effects on growth and on protein and energy metabolism in growing pigs. Pigs were fed semi-synthetic isoenergetic and isonitrogenous diets at 50% protein requirement with either soy protein isolate (SPI) or casein (CAS) as sole protein source. Intake of protein and ME amounted to 9% w/w and 1800 kJ x kg BW (-0.62) x d(-1) in Exp. 1, respectively, and 9% w/w and 1430 kJ x kg BW(-0.62) x d(-1) in Exp. 2. The CAS diet was supplemented by Lys, Met, Thr and Trp. In Exp. 1 (acute effects), 18 pigs received the CAS diet for 24 days (period 1); 9 pigs were then switched to a SPI diet whereas 9 pigs continued on the CAS diet for another 31 days (period 2). In Exp. 2, a third period of 31 days was added in which the SPI group was switched back to CAS diet. The control group was fed on the CAS diet throughout Exp. 2 (86 days). Altogether the majority of parameters were not affected neither comparing SPI with CAS in Exp. 1 nor inspecting possible persistence of effects in Exp. 2. In detail, in Exp. 1 SPI compared to CAS feeding resulted in a lower efficiency of protein utilisation and lower protein retention. Attendant upon the lower protein retention an increased energy retention as fat was only observed in tendency. SPI feeding caused a decreased body weight, thyroid weight and increased hepatic carbohydrate content that persisted after the diet was changed back to CAS (Exp. 2).     

Time course of glycogen accumulation after eccentric exercise.

This study examined the time course of glycogen accumulation in skeletal muscle depleted by concentric work and subsequently subjected to eccentric exercise. Eight men exercised to exhaustion on a cycle ergometer [70% of maximal O2 consumption (VO2max)] and were placed on a carbohydrate-restricted diet. Approximately 12 h later they exercised one leg to subjective failure by repeated eccentric action of the knee extensors against a resistance equal to 120% of their one-repetition maximum concentric knee extension force (ECC leg). The contralateral leg was not exercised and served as a control (CON leg). During the 72-h recovery period, subjects consumed 7 g carbohydrate.kg body wt-1.day-1. Moderate soreness was experienced in the ECC leg 24-72 h after eccentric exercise. Muscle biopsies from the vastus lateralis of the ECC and CON legs revealed similar glycogen levels immediately after eccentric exercise (40.2 +/- 5.2 and 47.6 +/- 6.4 mmol/kg wet wt, respectively; P greater than 0.05). There was no difference in the glycogen content of ECC and CON legs after 6 h of recovery (77.7 +/- 7.9 and 85.1 +/- 4.9 mmol/kg wet wt, respectively; P greater than 0.05), but 18 h later, the ECC leg contained 15% less glycogen than the CON leg (90.2 +/- 8.2 vs. 105.8 +/- 8.9 mmol/kg wet wt; P less than 0.05). After 72 h of recovery, this difference had increased to 24% (115.8 +/- 8.0 vs. 153.0 +/- 12.2 mmol/kg wet wt; P less than 0.05). These data confirm that glycogen accumulation is impaired in eccentrically exercised muscle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma aldosterone and sweat sodium concentrations after exercise and heat acclimation

This investigation was designed to determine the relationship between the levels of plasma aldosterone and eccrine sweat gland sodium excretion following exercise and heat acclimation. Ten subjects exercised at 45% of their maximal O2 uptake in a hot (40 degrees C), moderately humid (45% relative humidity) environment for 2 h/day on ten consecutive days. Acclimation was verified by significant reductions in exercise heart rate, rectal temperature, and heat storage, as well as significant elevation of resting plasma volume (12%, P less than 0.05) and exercise sweat rate on day 10 compared with day 1 of acclimation. During exercise, the concentration and total content of sodium in sweat as well as plasma aldosterone were significantly decreased from day 1 to day 10. The ratio of sweat sodium reabsorbed to plasma aldosterone concentration was significantly increased from day 1 to day 10 after both 1 and 2 h of exercise. These data indicate that plasma aldosterone concentrations decrease following heat acclimation; and eccrine gland responsiveness to aldosterone, as represented by sweat sodium reabsorption, may be augumented through exercise and heat acclimation.     

Influence of 4-week and 8-week exercise training on the pharmacokinetics and pharmacodynamics of intravenous and oral azosemide in rats

Cytochrome P450 expression was determined in the livers of control, 4-week exercised (4WE) and 8-week exercised (8WE) rats. Even though the 4-week and 8-week exercise training caused 53 and 25% increases, respectively, in total cytochrome P450 contents in the liver, exercise training did not cause any changes in the levels of P450 1A2 (which primarily metabolizes azosemide), 2E1 and 3A23 in the liver, as assessed by both Western and Northern blot analyses. Also, exercise training failed to alter the activity of NADPH-dependent cytochrome P450 reductase. The plasma concentrations of norepinephrine and epinephrine were significantly (2 to 3 folds) higher in 4WE rats than in controls, presumably due to physical stress, but the catecholamine levels in 8 WE rats returned to control levels. After intravenous administration (10 mg/kg of azosemide), the amount of unchanged azosemide excreted in 8-h urine (Ae(Azo, 0-8 h)) was significantly greater (46% increase) in 4WE rats than that in control rats. This resulted in a significantly faster (82% increase) renal clearance of azosemide. However, the nonrenal clearances were not significantly different between control and 4WE rats. The significantly greater Ae(Azo, 0-8 h) in 4WE rats was mainly due to a significant increase in intrinsic active secretion of azosemide in renal tubules and not due to a decrease in the metabolism of azosemide. After oral administration (20 mg/kg), Ae(Azo, 0-8 h) was also significantly greater (264%) in 4WE rats and this again was due to a significant increase in intrinsic active renal secretion of azosemide and not due to an increase in gastrointestinal absorption. After both intravenous and oral administration, the 8-h urine output was not significantly different between control and 4WE rats although Ae(Azo, 0-8 h) increased significantly in 4WE rats. This could be due to the fact that the urine output reached a plateau at 10 mg/kg after intravenous administration and 20 mg/kg after oral administration of azosemide to rats and possibly due to increase in plasma antidiuretic hormone levels and aldosterone production in 4WE rats.     

Effect of high dietary fat content on heat production and lipid and protein deposition in growing immunocastrated male pigs

In immunocastrated (IC) pigs, revaccination (V2) increases lipid deposition (LD) because of increased voluntary feed intake; but little is known on associated effect of diet composition on partitioning of nutrients in IC pigs. Digestibility measurements, N and energy balances in respiration chambers were performed in two subsequent stages in four replicates of two male littermates to determine the changes between 85 (stage 1) and 135 (stage 2) kg live weight due to combined effect of IC, growth and increased feed intake (IC/growth). During stage 1, pigs received a standard low-fat diet (LF diet; 2.5% dry matter (DM) of fat fed at 2.27 MJ metabolizable energy (ME)/kg BW^0.60 per day), whereas during stage 2, feed intake was increased to 2.47 MJ ME/kg BW^0.60 per day and one littermate was fed LF diet whereas the second received a fat-enriched diet (HF diet; 8.9% DM of fat) to determine the effect of increased dietary fat content on energy utilization in IC pigs. Results from N balance and measurements of gas exchanges were used to calculate respiratory quotient (RQ), heat production (HP), nutrient contribution to fat retention, components of HP, protein deposition (PD) and LD. Nutrients and energy apparent digestibility coefficients, methane losses and N retention (P<0.05) increased with IC/growth. Despite higher ME intake, total HP remained similar (1365 kJ/kg of BW^0.60 per day; P=0.47) with IC/growth. Consequently, total retained energy (RE) increased with IC/growth (from 916 to 1078 kJ/kg of BW^0.60 per day; P<0.01) with a higher fat retention (625 to 807 kJ/kg BW^0.60 per day; P<0.01), originating mainly from carbohydrates associated with a higher lipogenesis (536 to 746 kJ/kg BW^0.60 per day; P<0.01) and RQ (1.095 to 1.145; P<0.01). Both PD (from 178 to 217 g/day; P=0.02) and LD (from 227 to 384 g/day; P<0.01) increased due to IC/growth. Feeding HF diet after IC was associated with increased crude fat digestibility (P<0.01) and increased RE as fat (807 to 914 kJ/kg BW^0.60 per day; P=0.03), originating mainly from dietary fat (P<0.01) and resulting in increased LD (384 to 435 g/day; P<0.01) and lower RQ (from 1.145 to 1.073; P<0.01). Altogether, present results indicate that increased fatness of IC pigs is a result of increased daily LD caused by higher energy intake and lower basal metabolic rate. In addition, LD is further enhanced by dietary energy enrichment with fat after V2.     

Protein and energy value of vinasse for pigs

A vinasse, originating as the condensed molasses residue from the microbial production of citric acid, was chemically analyzed and given to growing pigs to determine its protein and energy value. It contained, per kg dry matter (62.6%), 185 g crude protein, 538 g N-free extracts, 48 g total sugar, 277 g ash and 12.8 MJ gross energy. Ammonia, betaine and amino acids (about half glutamic acid) accounted for 3.5, 9.1 and 28.6%, respectively, of the crude-protein N. In a 25-day balance trial with the final 10 days as collection period, ten pigs initially weighing 33 kg were pair-fed daily an average of about 1 kg of dry matter of either a basal diet (95% ground barley plus 5% cellulose) or of a mixed diet composed of, on dry basis, 77% basal diet plus 23% vinasse. Partial digestibility of components in the vinasse was: organic matter, 52%; crude protein, 45%; N-free extract, 58%; ash, 83%; and gross energy, 42%. Average daily gain and N retention were not different between dietary groups. The vinasse contained, per kg dry matter, 5.40 MJ DE and 3.61 MJ ME compared with 14.96 MJ DE and 14.48 MJ ME for the dry basal diet. The conclusion is that this vinasse, according to its low protein and energy value, can provide only a small percentage of the daily ration for pigs.