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M F Fuller

Publications and source records attributed to M F Fuller.

At least 55 records · Page 3Linked to original sources
PubMed1987

Effects of the amount and quality of dietary protein on nitrogen metabolism and heat production in growing pigs.

1. Eight pigs with a mean weight of 48 kg were given, at a constant daily rate, diets of low (0.15) or high (0.30) protein content, very deficient in lysine, with or without a supplement of L-lysine (3.7 g/kg). 2. Measurements of nitrogen and energy metabolism were made in four successive 14 d periods in a Latin-square design. 3. The rate of protein accretion was substantially increased by increases in both protein and lysine supply, but the rate of heat production was not significantly changed. 4. The rate of fat deposition varied inversely with the rate of protein accretion, being reduced by both protein and lysine supplements. 5. The relation between heat production and protein accretion (allowing for a constant energy cost of fat deposition) suggested that heat production increased with additional protein accretion less when protein quality was improved than when more protein was given.

Animals↗
PubMed1987

Effects of the amount and quality of dietary protein on nitrogen metabolism and protein turnover of pigs.

1. The interrelation between protein accretion and whole-body protein turnover were studied by varying the quantity and quality of protein given to growing pigs. 2. Diets with 150 or 290 g lysine-deficient protein/kg were given in hourly meals, with or without lysine supplementation, to female pigs (mean weight 47 kg). 3. After the animals were adapted to the diets, a constant infusion of [14C]urea was given intra-arterially for 30 h, during the last 6 h of which an infusion of [4,5-3H]leucine was also infused at a constant rate. At the same time, yeast-protein labelled with 15N was given in the diet for 50 h. 4. The rate of urea synthesis was estimated from the specific radioactivity (SR) of plasma urea. The rate of leucine flux was estimated from the SR of plasma leucine. The irrevocable breakdown of leucine was estimated from the 3H-labelling of body water. Total N flux was estimated from the 15N-labelling of urinary urea. 5. Addition of lysine to the low-protein diet significantly increased N retention, with a substantial reduction in leucine breakdown, but there was no significant change in the flux of leucine or of total N. 6. Increasing the quantity of the unsupplemented protein also increased N retention significantly, with concomitant increases in leucine breakdown and in the fluxes of leucine and of total N. 7. It is concluded that a doubling of protein accretion brought about by the improvement of dietary protein quality is not necessarily associated with an increased rate of whole-body protein turnover.

Amino Acids↗
PubMed1987

Urea synthesis and leucine turnover in growing pigs: changes during 2 d following the addition of carbohydrate or fat to the diet.

1. Studies have been made of the time-sequence of protein metabolic and hormonal changes following an abrupt increase in carbohydrate or fat intake. [3H]leucine and [14C]urea were infused for 72 h, via the aorta, into fourteen female pigs (30-38 kg body-weight). At 24 h after the start of the infusion their feed was either changed to one of two isonitrogenous diets containing additional starch (group BS, five animals) or fat (group BF, five animals), or remained unaltered (group BB, four animals). The distribution space of urea was measured by the dilution of a single dose of [14C]urea given both 48 h before and 48 h after the change in diet. The changes in the concentration and specific radioactivity of blood leucine were used to infer changes in protein turnover and those of plasma urea to measure total amino acid catabolism. The concentrations of blood glucose and plasma insulin and cortisol were also measured at approximately two-hourly intervals for the 48 h period following the change in diet. 2. Within 4 h of either change in diet blood leucine concentration was lowered and the leucine specific radioactivity was raised above that in group BB, but after 24 h both the concentration and specific radioactivity of leucine returned to values similar to those in group BB. Eventually the blood leucine specific radioactivity was slightly but not significantly reduced below that of group BB. 3. The addition of starch to the diet significantly reduced the synthesis and concentration of urea within 4 h but, although the addition of fat to the diet eventually lowered the urea concentration and synthesis, both changes were delayed for 18-24 h. 4. In group BS plasma glucose and insulin rose after the addition of starch, but after 24-36 h both returned to values that were the same as those in the animals that received the same diet throughout (group BB). The addition of fat to the diet altered neither blood glucose nor plasma insulin concentrations. The addition of either carbohydrate or fat to the diet eventually reduced plasma cortisol concentrations, but the change did not occur until 24 h after the change in diet. 5. The results suggest that alterations in non-protein energy supply exert their immediate effect on the degradation of whole-body protein. They do not exclude the possibility that these early changes may reflect opposing changes at different sites.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Protein synthesis and retention in some tissues of the young pig as influenced by dietary protein intake after early-weaning. Possible connection to the energy metabolism.

Changes in fractional protein synthesis rates (FSR) of 4 tissues (muscle, liver, intestine and bone) were assessed in 2 groups of young pigs from weaning, 10 days postpartum, to one week later, after feeding equal amounts of dry diets at 2 levels of protein (15 and 30%). In the meantime, protein and energy balance measurements were performed on the whole body partitioned into 4 components (carcass, liver, digestive organs, other organs + blood). Whole body energy balances were strongly negative in both groups as a result of low metabolisable energy (ME) intakes and fat mobilization. Protein balance improved, with the increase in dietary protein, at the expense of additional body fat loss. Parallel to that, an increase in the efficiency of ME for protein deposition was noticed. With the lower protein intake, protein deposition remained significantly positive in digestive tissues but not in liver and carcass. Muscle and liver RNA: protein ratios decreased after weaning at rates consistent with the normal age-dependent variations regardless of diet. FSRs were directly related to protein intake and the high supply allowed these tissues to match the preweaning values. In contrast, intestine RNA: protein ratio did not change after weaning and FSR was increased in both groups, with a trend to a higher value with the lower protein supply. Bone RNA: protein ratio and FSR both decreased after weaning on the low-protein diet; the effect of increasing dietary nitrogen could not be assessed in this tissue. The most typical effect of underfeeding associated with early-weaning seems to be an exaggeration of the normal age-dependent increase in protein synthesis per unit of RNA, provided that an adequate protein diet is fed. The relevance of these findings to the variations in the ME efficiency for protein deposition needs further investigations.

Animals↗
PubMed1983

Energy and nitrogen metabolism of lactating rabbits.

Twelve crossbred does (New Zealand White x California) were offered a diet of high protein and metabolizable energy content (249 g/kg dry matter (DM) and 13.6 MJ/kg DM respectively) throughout a 32 d lactation at one of four feeding levels (240, 280, 320 or 360 g/d). Each feeding level was replicated three times. Milk output was measured by weighing the does before and after their one daily suckling period. The lactation was divided into four consecutive 8-d periods. Each doe was placed in a direct calorimeter for 48 h around the mid-point of each of these periods and measurements of energy exchange were made. Nitrogen balance was also measured throughout the study period. Milk samples were taken from a parallel group of animals and the estimates of milk composition were applied to the main group of does. From the second period of lactation onwards nearly all does mobilized body tissue to support milk energy secretion, although there was no loss of weight. Multiple regression analyses were used to examine the apparent efficiency with which metabolizable energy and body-tissue energy were utilized for milk production. Overall, the relationship was described by the equation: (formula; see text) where Milk E is the milk energy output, ME intake is the metabolizable energy intake and Body ER is the body energy retention, all expressed in kJ/kg body-weight0.75 per d. All does appeared to be in positive N balance throughout lactation on this high-protein diet.

Animals↗
PubMed1983

Energy and nitrogen balances in young pigs maintained at constant weight with diets of differing protein content.

Pigs of 7 kg were fed diets containing 25% (diet 25), 8% (diet 8) or 2.5% (diet 2) protein per kilogram in quantities sufficient to maintain constant body weight for 42 days. Another group was fed diet 25, but these animals were pair-fed to animals fed diet 2. The average daily metabolizable energy required for weight stasis by the pigs fed diet 2 was nearly twice as great as that taken by pigs fed diet 25. The lipid content of the pigs was approximately 107 g/kg at the start and at the end of 42 days was 195 g/kg in pigs fed diet 2, 75 g/kg in pigs fed diet 8 and only 11 g/kg in pigs fed diet 25. The gains or losses of body energy computed from the changes in body N and lipid agreed well with those estimated directly by bomb calorimetry of carcass samples. Taken as a whole, the results do not support the suggestion that diets extremely low in protein elicit an increase in heat production greatly in excess of that expected from the results of calorimetric studies with animals fed conventional diets.

Animals↗
PubMed1980

Protein turnover in growing pigs. Effects of age and food intake.

1. Measurements were made of the nitrogen and energy balances of pigs of 30, 60 and 90 kg given a conventional diet at various daily rates. 2. Body protein synthesis was estimated from the irreversible loss of leucine from the blood following the infusion of [1-14C]leucine, and from the oxidation of the labelled amino acid. 3. Protein synthesis (g/d) increased by 2.17 for each 1 g increase in daily protein accretion and by 1.55 for each 1 g increase in daily protein intake. 4. At 30 kg, pigs close to energy equilibrium synthesized 270 g protein daily compared with 406 g and 512 g when their ration supplied twice and three times their maintenance requirement. 5. There was a close correlation between the daily urinary excretion of urea + ammonia and total amino acid catabolism estimated from the catabolism of leucine, but the latter underestimated the observed excretion by 2.5 g N/d. 6. The results imply that protein turnover accounts for only a proportion of the heat production associated with protein deposition.

Aging↗
PubMed1979

The optimal amino acid supplementation of barley for the growing pig. 1. Response of nitrogen metabolism to progressive supplementation.

1. In five experiments, involving 142 female pigs weighing on average 33 kg, estimates were made of the amounts of essential amino acids which minimized urinary N excretion when diets with barley as the only source of protein were given at the rate of 120 g/kg0.75 per d. 2. With additions of lysine (4.0 g/kg diet) and threonine, (1.2 g/kg diet) to barley urinary N excretion decreased from 0.91 to 0.36 g/kg0.75 per d, corresponding to an increase in biological value (bv) from 0.51 to 0.86. 3. With these additions of lysine and threonine, there were no responses to additions of tryptophan, methionine or isoleucine, or to further additions of lysine or threonine, but addition of histidine significantly reduced N excretion. 4. No optimal addition of histidine could be determined; the mean rate of N excretion after addition of histidine (not less than 0.3 g/kg diet) was 0.27 g/kg0.75 per d, corresponding to a BV of 0.93. 5. There was a variation between pigs from different litters in their responses to added histidine. Those with low rates of N excretion on the unsupplemented diet did not respond to additions of histidine, but those with high rates did. 6. It is concluded that additions of only three amino acids can greatly improve the nutritive value of barley protein for the growing pig and that the amino acid composition of the supplemented protein closely approaches the ideal; it is also similar to whole-body tissue protein.

Amino Acids, Essential↗
PubMed1979

The amino acid supplementation of barley for the growing pig. 2. Optimal additions of lysine and threonine for growth.

1. Thirty-three diets were made by adding to ground barley combinations of L-lysine (0--6.0 g/kg) and L-threonine (0--3.0 g/kg), together with vitamins and minerals. Each was given to two female and two castrated male pigs during their growth from 25 to 60 kg. 2. Growth rate increased from 0.36 kg/d to a maximum of 0.65 kg/d with additions of 3.8 g L-lysine/kg and 1.8 g L-threonine/kg; these values and the maximum gains achieved were slightly higher for castrates than for females. Minimum values for food conversion ratio of 2.84 for castrates and 3.06 for females were achieved with similar amino acid additions to those giving fastest growth. 3. Carcass fat, estimated by sepcific gravity, was least with the addition of 5.9 g L-lysine/kg, but continued to decrease up to the highest threonine concentrations. Backfat thickness was also reduced by amino acid additions but failed to reach a minimum.

Adipose Tissue↗
PubMed1977

The protein-sparing effect of carbohydrate. 1. Nitrogen retention of growing pigs in relation to diet.

1. Measurements were made of the losses of nitrogen in the faeces and urine of sixty pigs of approximately 33 kg, given dietary regimens comprising twenty-nine combinations of fish flour (0-800 g/d) and maize starch (0-1200 g/d). 2. The results were used to develop a generalized equation describing N retention as a joint function of N intake and starch intake. 3. The protein-sparing effect of starch was exerted in all circumstances. It was greatest when protein intake exceeded 220 g/d but some effect persisted with protein-free diets. With a high protein supply, the increase in N retention per unit increase in dietary starch decreased from 36 mg/g with the first increment to 3 mg/g with the highest attainable starch intake. 4. From the generalized equation the relationships between net protein utilization and protein concentration and food intake could be described as continuous functions. The equations may be of use in comparing the protein values of diets measured under non-standardized conditions.

Animals↗
PubMed1977

The protein-sparing effect of carbohydrate. 2. The role of insulin.

1. In five experiments with growing female pigs of 38-63 kg, insulin (2 mU/kg) per min) and glucose (9-17 mg/kg per min) were infused continuously for 3-7 d. In three further experiments, glucose (9 mg/kg per min) was infused alone for 5 d. 2. In response to the combined infusion, plasma insulin increased 2-7-fold, plasma glucose decreased, on average, by 50% and plasma urea concentration was reduced by 40%. Urinary excretion of urea and nitrogen decreased after the first day of infusion to values averaging 70% of control levels. 3. The infusion of glucose alone provoked only a small increase in plasma insulin. The reduction of urinary urea and of N excretion were approximately 25% of those observed with the combined infusions.

Animals↗