Bacterial protein meal in diets for pigs and minks: comparative studies on protein turnover rate and urinary excretion of purine base derivatives

The effect of increasing the dietary content of bacterial protein meal (BPM) on protein turnover rate, and on nucleic acid and creatinine metabolism in growing minks and pigs was investigated in two experiments. In each experiment, 16 animals were allocated to four experimental diets. The diets containing no BPM served as controls, i.e. for minks diet M1, for pigs P1; the experimental diets contained increasing levels of BPM to replace fish meal (minks) or soybean meal (pigs), so that up to 17% (P2), 20% (M2), 35% (P3), 40% (M3), 52% (P4), and 60% (M4) of digestible N was BPM derived. Protein turnover rate was measured by means of the end-product method using [15N]glycine as tracer and urinary nitrogen as end-product. In minks, protein flux, synthesis, and breakdown increased significantly with increasing dietary BPM. In pigs, diet had no observed effect on protein turnover rate. The intake of nucleic acid nitrogen (NAN) increased from 0.15 g/kg W0.75 on M1 to 0.26 g/kg W0.75 on M3 and M4 in the mink experiment, and from 0.08 g/kg W0.75 on P1 to 0.33 g/kg W0.75 on P4 in the pig experiment. Increased NAN intake led, in both experiments, to increased allantoin excretion. Analysis of species effects showed that minks excreted 1.72 mmol/ kg W0.75 of allantoin, significantly more than the 0.95 mmol/kg W0.75 excreted by pigs. In minks, approximately 96% of the excreted purine base derivatives consisted of allantoin, whereas in pigs approximately 93% did. Thus, increasing the dietary content of BPM increased protein turnover rate in minks but not in pigs, and allantoin excretion increased with increasing dietary BPM although it seemed that mink decomposed purine bases to their end-product more completely than pigs did. Collectively these data show that BPM is a suitable protein source for pigs and mink, and recorded differences between species were to a large extent due to differences in protein retention capacity and muscle mass.     

Effect of bacterial protein meal on protein and energy metabolism in growing chickens

Abstract

This experiment investigates the effect of increasing the dietary content of bacterial protein meal (BPM) on the protein and energy metabolism, and carcass chemical composition of growing chickens. Seventy-two Ross male chickens were allocated to four diets, each in three replicates with 0% (D0), 2% (D2), 4% (D4), and 6% BPM (D6), BPM providing up to 20% of total dietary N. Five balance experiments were conducted when the chickens were 3 – 7, 10 – 14, 17 – 21, 23 – 27, and 30 – 34 days old. During the same periods, 22-h respiration experiments (indirect calorimetry) were performed with groups of 6 chickens (period 1), 5 chickens (period 2), and one chicken (periods 3 – 5). After each balance period, one chicken in each cage was killed and the carcass weight was recorded. Chemical analyses were performed on the carcasses from periods 1, 3, and 5. Weight gain, feed intake, and feed conversion rate were found to be similar for all diets. Chickens on D0 retained 1.59 g N · kg^?0.75 · d^?1, significantly more than chickens on D2, D4, and D6, which retained 1.44 g, 1.52 g, and 1.50 g N · kg^?0.75 · d^?1, respectively. This was probably caused by the higher nitrogen content of D0. Neither the HE (p = 0.92) nor the retention of energy (p = 0.88) were affected by diet. Carcass composition was similar between diets, in line with the values for protein and energy retention found in the balance and respiration experiments. It was concluded that the overall protein and energy metabolism as well as carcass composition were not influenced by a dietary content of up to 6% BPM corresponding to 20% of dietary N.     

Bacterial protein meal in diets for growing pigs: effects on protein and energy metabolism

This experiment investigated the effects of increasing the dietary content of bacterial protein meal (BPM) on the protein and energy metabolism of pigs from weaning to a live weight of 80 kg. Four litters with four castrated male pigs in each litter were used. The litters were divided into two blocks according to age. One pig from each litter was fed one of the four experimental diets. Soya-bean meal was replaced with BPM on the basis of digestible protein, and the BPM contents in the four diets were 0% (BP0), 5% (BP5), 10% (BP10) and 15% (BP15), corresponding to 0%, 17%, 35% and 52% of the digestible nitrogen (N), respectively. Four balance periods were performed, at the start of which the pigs weighed 9.5 kg, 20.7 kg, 45.3 kg and 77.2 kg, respectively. Once during each balance period, 22-h respiration experiments were performed using indirect calorimetry. Daily weight gain, feed intake and feed conversion rate were the same for all diets. The apparent digestibility of N was lower on diet BP10 than on BP0 (P = 0.002), whereas the apparent digestibility of energy was similar on all diets. The retention of nitrogen did not differ between diets and was 1.50, 1.53, 1.33 and 1.46 g N per kg^0.75 per day on BP0, BP5, BP10 and BP15, respectively. Neither metabolisable energy intake nor heat production were affected by inclusion level of BPM. Retention of energy was 620 (BP0), 696 (BP5), 613 (BP10) and 664 kJ/kg^0.75 per day (BP15), the differences among diets being non-significant. The N-free respiratory quotient was similar on all diets. It was concluded that the overall protein and energy metabolism in growing pigs were not affected when up to 50% of dietary N was derived from BPM.     

Study of crude protein intake and growth response in captive subadult giant pandas (Ailuropoda melanoleuca)

Feeding trials were conducted on seven subadult giant pandas (1.5–4.7 years old). The giant pandas consumed diets with 20 various levels of crude protein (CP): 132.9, 186.8, 206.0, 233.1, 251.4, 255.2, 288.5, 290.8, 299.1, 334.6, 370.7, 378.7, 379.9, 399.2, 372.6, 411.4, 436.1, 484.4, 509.3, and 563.7 g/day. According to the differences in the body weight (BW) gain (weight/month (W/M)) and the amounts of ingested CP, subadult giant pandas are divided into at least three age groups: 1.5–2.0, 2.5–3.9, and 4.0–4.7 years. Although there apparently is no direct relationship between the ΔW/M and the CP consumed by all the giant pandas, a linear relationship existed between the square root of CP ingested (g) per unit BW (W^0.75, Kg) and weight gain per month (ΔW/M, Kg/M) of giant pandas aged 1.5–2.0 years. No such relationship existed in the giant pandas aged 2.5–4.7 years, but ΔW/M decreased with the increasing CP per unit gross energy (GE) consumed (CP/GE). For the 1.5–2.0‐year‐old giant pandas, CP for maintenance was determined at 3.6576 g/Kg W^0.75/day when ΔW/M was 0, and CP for growth was 1.7541 g/Kg W^0.75/day when ΔW/M was equal to 1 Kg/M; thus, suitable intake of total CP is 9.95 g/Kg W^0.75/day. The average value of ingested CP was 13.54 ± 3.01 g/KgW^0.75/day for 2.5–3.9‐year‐old pandas, and 12.25 g/KgW^0.75/day for 4.5–4.7‐year‐old pandas. Zoo Biol 21:223–232, 2002. © 2002 Wiley‐Liss, Inc.     

Nitrogen and energy balance in growing mink (Mustela vison) fed different levels of bacterial protein meal produced with natural gas

The objective of this study was to estimate the effect of increasing the dietary content of bacterial protein meal (BPM) on energy and protein metabolism in growing mink kits. Sixteen male mink kits of the standard brown genotype were randomly fed one of four diets: A control (Diet I) based on high-quality fish meal, and three experimental diets in which 20% (Diet II), 40% (Diet III) and 60% (Diet IV) of the digested nitrogen (DN) was replaced with BPM. Nitrogen balance and respiration experiments (indirect calorimetry) were carried out when the animals were approximately 9.5, 14.5, 17.5, 23.5 and 28.5 weeks of age. The apparent digestibility of crude protein and energy decreased significantly with increasing dietary BPM. The retained nitrogen was 0.45, 0.54, 0.52 and 0.40 g/kg0.75 on Diets I, II, III and IV, respectively, the observed differences between diets being non-significant (p = 0.06). Heat production (HE) was between 645 and 665 kJ/kg0.75 on all diets (p = 0.78). Retained energy (RE) was approximately 150-160 kJ/kg0.75 on Diets I to III, whereas it was -11 kJ/kg0.75 on Diet IV, the differences being significant (p< 0.001). A lower feed intake and apparent digestibility of energy caused the negative RE on Diet IV. The amount of HE from oxidation of protein decreased from 32.7% on Diet I to 26.6% on Diet IV, and oxidation of fat increased from 53.8% on Diet I to 63.5% Diet IV. In conclusion, protein and energy metabolism remained unaffected when up to 40% of DN was derived from BPM.     

Effects of Dietary Copper on Nutrient Digestibility,Tissular Copper Deposition and Fur Quality of Growing-Furring Mink (Mustela vison)

The present study investigated the effects of dietary copper (Cu) on growth performance and fur quality in growing-furring minks. One hundred and five standard dark female minks were randomly assigned to seven groups with the following dietary treatments: basal diet with no supplemental Cu (control) and basal diet supplemented with either 6, 12, 24, 48, 96 or 192 mg/kg Cu from copper sulphate, respectively. Our data showed that final body weight (P?=?0.033), daily gain (P?=?0.029) and fat digestibility (P?=?0.0006) responded to increasing levels of Cu. The activity of glutamic-oxalacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) in serum increased (linear and quadratic, P?<?0.05) as Cu increased in the diet. Increasing Cu improved total protein (TP) and albumin (ALB) (quadratic, P?<?0.05). The level of ceruloplasmin (CER) responded in a linear (P?<?0.0001) and quadratic (P?<?0.0001) form with increasing level of Cu. Colour intensity of those minks pelted suggested that relatively high levels of supplemental Cu have a beneficial effect on intensifying hair colour of dark mink but did not affect leather thickness. Liver Cu and plasma Cu concentrations of the mink linearly (P?<?0.0001) responded to increasing levels of Cu. Our results indicate that growing-furring mink can efficiently utilize added dietary fat and that Cu plays an important role in the digestion of dietary fat in growing-furring mink, and supplemental dietary Cu in growing-furring mink promotes fat digestion and improve hair colour.     

Whole-body protein turnover reveals the cost of detoxification of secondary metabolites in a vertebrate browser

The detoxification limitation hypothesis predicts that the metabolism and biotransformation of plant secondary metabolites (PSMs) elicit a cost to herbivores. There have been many attempts to estimate these costs to mammalian herbivores in terms of energy, but this ignores what may be a more important cost—increases in protein turnover and concomitant losses of amino acids. We measured the effect of varying dietary protein concentrations on the ingestion of two PSMs (1,8 cineole—a monoterpene, and benzoic acid—an aromatic carboxylic acid) by common brushtail possums (Trichosurus vulpecula). The dietary protein concentration had a small effect on how much cineole possums ingested. In contrast, protein had a large effect on how much benzoate they ingested, especially at high dietary concentrations of benzoate. This prompted us to measure the effects of dietary protein and benzoate on whole-body protein turnover using the end-product method following an oral dose of [¹⁵N] glycine. Increasing the concentration of dietary protein in diets without PSMs improved N balance but did not influence whole-body protein turnover. In contrast, feeding benzoate in a low-protein diet pushed animals into negative N balance. The concomitant increases in the rates of whole-body protein turnover in possums eating diets with more benzoate were indicative of a protein cost of detoxification. This was about 30 % of the dietary N intake and highlights the significant effects that PSMs can have on nutrient metabolism and retention.     

Effect of dietary protein level on carcass traits and meat properties of Cinta Senese pigs

The aim of this study was to test the effect of various dietary protein contents (CP) on the carcass traits and the meat quality of Cinta Senese pigs. A total of 60 Cinta Senese pigs were equally distributed in four dietary groups that were balanced for sex (barrows and gilts) and live weight. The animals in the groups were fed one of four diets (80CP, 100CP, 130CP and 160CP) containing different CP contents (80, 100, 130 and 160 g/kg, respectively). The diets were administered to the pigs during the entire growing–fattening period in a controlled dose of 90 g/kg W^0.75, to a maximum of 2.5 kg/day per animal. The duration of the trial was ~250 days, ending when the animals reached the target slaughter weight of 145 kg. The 80CP diet produced fatter carcasses than did the other diets; no differences in carcass composition were found among the animals fed the other three diets (total lean cuts: 57.4%, 61.4%, 60.8% and 61.3% for 80CP, 100CP, 130CP and 160CP diet, respectively). The sample joint composition confirmed the highest fatness and the lowest meatiness of pigs fed 80CP. This same pattern was evident for the composition of the muscle (Longissimus lumborum) containing the largest amount of i.m. fat, and the lowest protein content in the 80CP group. Moreover, the 80CP diet resulted in the lightest and yellowest meat with the highest cooking loss. A principal component analysis of the physical and chemical traits of the meat revealed three first factors that explained 56% of the total variance. Among them, only the intersection of Factor1, which combined mainly lower pH at 24 h postmortem and higher drip loss, cooking loss, lightness and yellowness, with Factor2, which associated higher toughness, higher protein and lower fat content, graphically appeared to discriminate the 80CP diet from the other ones. In conclusion, a diet with 80 g/kg of CP content was inadequate for this local breed, while, in consideration of the cost of protein feed and the need to reduce N pollution, the 100CP diet would be an optimal compromise for the growth–fattening of Cinta Senese pigs.     

Blood parameters in growing pigs fed increasing levels of bacterial protein meal

The experiment investigated the effects of increasing dietary levels of bacterial protein meal (BPM) on various blood parameters reflecting protein and fat metabolism, liver function, and purine base metabolism in growing pigs. Sixteen barrows were allocated to four different experimental diets. The control diet was based on soybean meal. In the other three diets soybean meal was replaced with increasing levels of BPM, approximately 17%, 35%, and 50% of the nitrogen being derived from BPM. Blood samples from the jugular vein were taken when the body weights of the pigs were approximately 10 kg, 21 kg, 45 kg, and 77 kg. The blood parameters reflecting fat metabolism and liver function were not affected by diet. Both the plasma albumin and uric acid concentrations tended to decrease (P = 0.07 and 0.01, respectively) with increasing dietary BPM content, whereas the plasma glucose concentration tended to increase (P = 0.07) with increasing dietary BPM content. It was concluded that up to 50% of the nitrogen could be derived from BPM without affecting metabolic function, as reflected in the measured blood parameters.     

Nitrogen excretion in rats on a protein-free diet and during starvation

Nitrogen balances (six days) were determined in male Wistar rats during feeding a diet with sufficient protein or a nearly protein-free diet (n = 2×24), and then during three days of starvation (n = 2×12). The objective was to evaluate the effect of protein withdrawal on minimum nitrogen excretion in urine (UN), corresponding to endogenous UN, during feeding and subsequent starvation periods. The rats fed the protein free-diet had almost the same excretion of urinary N during feeding and starvation (165 and 157 mg/kg W^0.75), while it was 444 mg/kg W^0.75 in rats previously fed with protein, demonstrating a major influence of protein content in a diet on Nexcretion during starvation. Consequently, the impact of former protein supply on Nlosses during starvation ought to be considered when evaluating minimum N requirement necessary to sustain life.     

Histidine maintenance requirement and efficiency of its utilization in young pigs

Abstract

An experiment was conducted in young pigs (initial BW 10.1 kg) to estimate the maintenance requirement for histidine and its efficiency of utilization for protein accretion using a comparative slaughter technique. Three groups of six pigs each were fed a purified diet supplying 0, 14 or 56 mg histidine per kg BW^0.75. Following 21 d of feeding, pigs were killed for whole body compositional analysis. A representative group of six pigs was killed at the beginning of the experiment. Retention of histidine and total N were the main criteria of response. Histidine retention (R² = 0.73) and N retention (R² = 0.78) were linear functions of histidine intake (p < 0.001). Histidine requirement for zero histidine retention was 15.5 mg/kg BW^0.75, whereas histidine required for zero N retention was 4.1 mg/kg BW^0.75. At zero histidine retention, the pigs retained daily 82 mg N/kg BW^0.75, presumably due to the degradation of histidine-rich compounds such as haemoglobin and/or carnosine. The slope of the regression line relating histidine retention to N retention indicated that 105 mg of histidine was deposited per gram of total N which was considerably less than the estimated histidine concentration in body protein (179 mg/g N). Based on the slopes of regression equations for histidine and N retention, marginal efficiency of histidine utilization was calculated to be 0.94 and 1.34, respectively.     

Bacterial protein meal produced on natural gas replacing soybean meal or fish meal in broiler chicken diets

Abstract

The effects of replacing soybean meal or fish meal with 2, 4 or 6% bacterial protein meal (BPM) on growth performance, ileal digestibility of amino acids and sensory quality of meat, were examined using 630 broiler chickens. Weight gain from 7 – 32 days of age did not differ significantly among the treatments. Efficiency of feed conversion was increased when BPM replaced soybean meal, and abdominal fat deposition tended to decline. Feed conversion was not affected when BPM replaced fish meal. Amino acid digestibility was unaffected or improved when BPM replaced soybean meal, whereas replacement of fishmeal with BPM resulted in similar digestibility. Sensory quality of fresh thigh meat was similar among treatments, but for freeze-stored chest meat replacement of fish meal with BPM reduced off-odour and off-flavour and increased juiciness. It was concluded that 6% BPM can replace soybean meal or fish meal protein in broiler chicken diets.     

Fluxes of nitrogen and phosphorus in a gallery forest in the Cerrado of central Brazil

The Gallery forests of the Cerrado biome play a critical role in controlling stream chemistry but little information about biogeochemical processes in these ecosystems is available. This work describes the fluxes of N and P in solutions along a topographic gradient in a gallery forest. Three distinct floristic communities were identified along the gradient: a wet community nearest the stream, an upland dry community adjacent to the woodland savanna and an intermediate community between the two. Transects were marked in the three communities for sampling. Fluxes of N from bulk precipitation to these forests resulted in deposition of 12.6 kg ha^?1 y^?1 of total N of which 8.8 kg ha^?1 was as inorganic N. The throughfall flux of total N was generally <8.4 kg ha^?1 year^?1. Throughfall NO₃?CN fluxes were higher (7?C32%) while NH₄?CN and organic N fluxes were lower (54?C69% and 5?C46%) than those in bulk precipitation. The throughfall flux was slightly lower for the wet forest community compared to other communities. Litter leachate fluxes differed among floristic communities with higher NH₄?CN in the wet community. The total N flux was greater in the wet forest than in the dry forest (13.5 vs. 9.4 kg ha^?1 year^?1, respectively). The stream water had total N flux of 0.3 kg ha^?1 year^?1. The flux of total P through bulk precipitation was 0.7 kg ha^?1 year^?1 while the mean fluxes of total P in throughfall (0.6 kg ha^?1 year^?1) and litter leachate (0.5 kg ha^?1 year^?1) declined but did not differ between communities. The low concentrations presented in soil solution and low fluxes in stream water (0.3 and 0.1 kg ha^?1 year^?1 for N and P, respectively) relative to other flowpaths emphasize the conservative nutrient cycling of these forests and the importance of internal recycling processes for the maintenance and conservation of riparian and stream ecosystems in the Cerrado.     

Covariance in water- and nutrient budgets of Dutch peat polders: what governs nutrient retention?

Water and nutrient budgets were constructed for 13 low-lying peat polders in the Netherlands that varied in elevation relative to sea level (?0.2 to ?2.4 m below sea level), land use (7–70% of the total polder area covered by agriculture; largely dairy farming), and surface water prevalence (6–43%). Water balances were verified with chloride budgets and accepted when both met the criterion (total inflows ? total outflows)/(total inflows) <0.05. Apart from precipitation and evapotranspiration (overall means 913 vs. 600 mm), in- and outlet (171 vs. 420 mm) as well as in- and outward seepage (137 vs. 174 mm) were important items in the water budgets. Nutrient budgets, however, were dominated by terms related to agricultural land use (~60% of all inputs, 90% of N-removal and 80% of P removal) rather than water fluxes (8% and 5% of N and P inputs; 6 and 18% of outputs). After agriculture (200 kg N ha^?1 y^?1), mineralisation of the peat soil and atmospheric deposition appear to be important inputs (about 94 and 21 kg N ha^?1 y^?1). Major output terms were agricultural output (209 kg N ha^?1 y^?1) and denitrification (95 kg N ha^?1 y^?1). The average N budget was in balance (difference ~1 kg N ha^?1 y^?1), whereas P accumulated in most polders, particularly those under agriculture. The mean P surplus (15 kg P ha^?1 y^?1 in the 9 mainly agricultural polders) corresponds well with the accumulated difference observed elsewhere (700 kg P ha^?1 in the upper 50 cm in a nature reserve versus 1400 under agriculture) after over 50 years of dairy farming. Bulk retention of N and P in these polders is taking place in the peat soil, through temporary sorption to the matrix and N is lost through denitrification. In a principal components analysis combining land use, landscape pattern, water balance and nutrient budget terms, the three-first principal components explained 63% of the variability. The first component (PC) correlated strongly with the percentage of land under agriculture (r = 0.82) and negatively with the percentage covered by surface water (r = ?0.74). Most input and output terms of the nitrogen budget also correlated with this PC. The second PC covaried distinctly with the total area of a polder (r = ?0.79) and human population density at municipality level (r = 0.75). Phosphorus loads in inlet and outlet water correlated with this PC. This suggests that the variability in nutrient budgets among polders is largely governed by agricultural land use.     

Lysine maintenance requirement and efficiency of its utilisation in young pigs as estimated by comparative slaughter technique

An experiment was carried out on weaner pigs (initial BW 10.8 kg) to estimate the maintenance requirement for lysine (Lys) and its marginal efficiency of utilisation using a comparative slaughter technique. Three groups of six pigs each were fed purified diets for 21 days supplying Lys at 19.5, 78 or 195 mg/kg W^0.75, which corresponded to 50, 200 or 500% of the assumed maintenance requirement. All other essential amino acids were given at 50% excess. At the end of the experiment, pigs were killed for whole-body nitrogen (N) and amino acid analysis. A representative group of six pigs was analysed at the beginning of the experiment. Based on regression equations, relating Lys or N retention to Lys intake, Lys requirement for zero Lys retention was estimated to be 121 mg/kg W^0.75, while Lys requirement corresponding to zero N retention was 41.7 mg/kg W^0.75. At N equilibrium, the pigs lost 65 mg of Lys per kg W^0.75 daily while at zero Lys retention, the daily N retention was 156 mg/kg W^0.75. The marginal efficiency of lysine utilisation was 0.91. It is concluded that zero lysine retention is a better criterion of lysine maintenance requirement than zero N retention.     

Effects of Different Dietary Manganese Levels on Growth Performance and N Balance of Growing Mink (Neovision vision)

Two experiments were conducted to study the effects of dietary manganese levels on growth performance, nutrients digestibility, and N balance of minks during growing period. In experiment 1, 75 healthy male minks (60 days old) were selected and randomly divided into five groups with different types of diet. The diet was supplemented with 0 (control), 50, 100, 300, and 600 ppm of manganese as MnSO₄ of dry matter (DM) in basic diet, respectively. From early July to middle September, the results showed that the final body weights of minks were significantly affected by diets (P?<?0.05). Average daily gains (ADG) were significantly higher in the 300-ppm manganese group than those in other groups. The ratio of feed to body weight gain (F/G) was significantly affected by manganese level (P?<?0.05). In experiment 2, 45 male minks (75 days old) with the same body weight were selected from each group of experiment 1 to carry out the nutrient digestion and N-balance tests which lasted for 4 days for the collection of the feces and urine, and the diets and treatment codes were same as in experiment 1. The results showed that no significant differences were found in DM, crude protein (CP), and crude carbohydrate (CC) digestibility among all groups (P?>?0.05), but ether extract (EE) and gross energy (GE) digestibility were all the highest in the 300-ppm group. N intake and fecal N were similar among all groups (P?>?0.05). Urinary N was lower in the 300-ppm group; in contrast, N retention was higher in this group (P?<?0.05). In conclusion of experiment 1 and experiment 2, the diet supplemented with 300 ppm of manganese (as manganese sulfate) could improve the growth performance and increase the EE and GE digestibility of mink during the growing period and moreover reduce the nitrogen emissions to the environment, and the optimal total manganese level in mink’s diet was 409.16 in DM during the growing period.     

Determination of endogenous fat loss and true total tract digestibility of fat in mink (Neovison vison)

The objective of this study was to determine the endogenous fat loss (EFL) and to calculate true total tract digestibility (TTTD) of fat in mink (Neovison vison) using soybean oil–based diets with different fat levels. In the digestibility assay, four diets with 6.30%, 13.9%, 22.0% and 34.0% fat in dry matter were used. Sixteen adult male mink were distributed in a complete randomised design. The apparent total tract digestibility (ATTD) of dietary fat was 90.8%, 95.9%, 96.9% and 97.8%, respectively. The apparent total digestible fat was linearly related to dietary fat intake (r² = 0.99). The EFL was estimated from the slope of the regression equation and was determined to be 5.09 g/kg DM intake. The TTTD of soybean oil was determined to be 99.3%. Therefore, TTTD values will have negligible impact in feed formulation as they are close to ATTD values with the dietary fat levels normally used for mink.     

Role of protein and amino acids in promoting lean mass accretion with resistance exercise and attenuating lean mass loss during energy deficit in humans

Amino acids are major nutrient regulators of muscle protein turnover. After protein ingestion, hyperaminoacidemia stimulates increased rates of skeletal muscle protein synthesis, suppresses muscle protein breakdown, and promotes net muscle protein accretion for several hours. These acute observations form the basis for strategized protein intake to promote lean mass accretion, or prevent lean mass loss over the long term. However, factors such as protein dose, protein source, and timing of intake are important in mediating the anabolic effects of amino acids on skeletal muscle and must be considered within the context of evaluating the reported efficacy of long-term studies investigating protein supplementation as part of a dietary strategy to promote lean mass accretion and/or prevent lean mass loss. Current research suggests that dietary protein supplementation can augment resistance exercise-mediated gains in skeletal muscle mass and strength and can preserve skeletal muscle mass during periods of diet-induced energy restriction. Perhaps less appreciated, protein supplementation can augment resistance training-mediated gains in skeletal muscle mass even in individuals habitually consuming ‘adequate’ (i.e., >0.8 g kg^?1 day^?1) protein. Additionally, overfeeding energy with moderate to high-protein intake (15–25 % protein or 1.8–3.0 g kg^?1 day^?1) is associated with lean, but not fat mass accretion, when compared to overfeeding energy with low protein intake (5 % protein or ~0.68 g kg^?1 day^?1). Amino acids represent primary nutrient regulators of skeletal muscle anabolism, capable of enhancing lean mass accretion with resistance exercise and attenuating the loss of lean mass during periods of energy deficit, although factors such as protein dose, protein source, and timing of intake are likely important in mediating these effects.     

Partitioning of late gestation energy expenditure in ewes using indirect calorimetry and a linear regression approach

Abstract

Late gestation energy expenditure (EE_gest) originates from energy expenditure (EE) of development of conceptus (EE_conceptus) and EE of homeorhetic adaptation of metabolism (EE_homeorhetic). Even though EE_gest is relatively easy to quantify, its partitioning is problematic. In the present study metabolizable energy (ME) intake ranges for twin-bearing ewes were 220 – 440, 350 – 700, 350 – 900 kJ per metabolic body weight (W^0.75) at week seven, five, two pre-partum respectively. Indirect calorimetry and a linear regression approach were used to quantify EE_gest and then partition to EE_conceptus and EE_homeorhetic. Energy expenditure of basal metabolism of the non-gravid tissues (EE_bmng), derived from the intercept of the linear regression equation of retained energy [kJ/W^0.75] and ME intake [kJ/W^0.75], was 298 [kJ/W^0.75]. Values of the intercepts of the regression equations at week seven, five, and two pre-partum were 311, 398, and 451 [kJ/W^0.75], respectively. The difference between the intercepts for different weeks was used to calculate EE_homeorhetic. The remaining part of EE_gest was considered to be EE_conceptus. In conclusion, the good agreement between our values of EE_conceptus and those in the literature indicates the method's validity.