Apparent digestibility and nutritional status of capuchin monkeys (Sapajus sp.) under human care.

BACKGROUND: Studing the nutritional needs and dietary habits of primates is essential to ensure their health and well-being. This includes the understanding of the use of nutrients and its correlation with health parameters. METHODS: Diet and nutritional parameters of 13 captive capuchin monkeys (Sapajus sp.) were assesed. Apparent digestibility of dry matter and nutrients were evaluated. Nutritional status was established based on body condition score (BCS) and muscle mass score (MMS). RESULTS: High apparent digestibility coefficients (ADC) were observed for crude protein and ether extract, but low for minerals and crude fiber. The ADC of EE and CF were related to MMS, and the biochemical parameters did not correlate with the AD coefficients obtained in the group. The nutritional status of the animals remained inadequate in 84.6% of the individuals, suggesting a reformulation of the diet and nutritional management.

Effects of swimming activity and feed restriction on antioxidant and digestive enzymes in juvenile rainbow trout: Implications for nutritional and exercise strategies in aquaculture.

BACKGROUND: In this study, we investigated the effects of swimming activity and feed restriction on digestion and antioxidant enzyme activities in juvenile rainbow trout (average body weight of 26.54 ± 0.36 g). METHODS: The stomach, liver and kidney tissues were obtained from four distinct groups: the static water group (fish were kept in static water and fed to satiation), the feeding restricted group (fish were kept in static water with a 25% feed restriction), the swimming exercised group (fish were forced to swimming at a flow rate of 1 Body Length per second (BL/s)) and the swimming exercised-feed restricted group (subjected to swimming exercise at a 1 BL/s flow rate along with a 25% feed restriction). We determined the levels of glutathione, lipid peroxidation and the activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and lactate dehydrogenase, as well as the presence of reactive oxygen species in the tissues obtained from the fish. Additionally, the activities of pepsin, protease, lipase and arginase in these tissues were measured. RESULTS: Swimming activity and feed restriction showed different effects on the enzyme activities of the fish in the experimental groups. CONCLUSION: It can be concluded that proper nutrition and exercise positively influence the antioxidant system and enzyme activities in fish, reducing the formation of free radicals. This situation is likely to contribute to the fish's development.

The bile salt/phospholipid ratio determines the extent of in vitro intestinal lipolysis of triglycerides: Interfacial and emulsion studies.

This study focused on the protein-stabilised triglyceride (TG)/water interfaces and oil-in-water emulsions, and explored the influence of varying molar ratios of bile salts (BSs) and phospholipids (PLs) on the intestinal lipolysis of TGs. The presence of these two major groups of biosurfactants delivered with human bile to the physiological environment of intestinal digestion was replicated in our experiments by using mixtures of individual BSs and PLs under in vitro small intestinal lipolysis conditions. Conducted initially, retrospective analysis of available scientific literature revealed that an average molar ratio of 9:4 for BSs to PLs (BS/PL) can be considered physiological in the postprandial adult human small intestine. Our experimental data showed that combining BSs and PLs synergistically enhanced interfacial activity, substantially reducing oil-water interfacial tension (IFT) during interfacial lipolysis experiments with pancreatic lipase, especially at the BS/PL-9:4 ratio. Other BS/PL molar proportions (BS/PL-6.5:6.5 and BS/PL-4:9) and an equimolar amount of BSs (BS-13) followed in IFT reduction efficiency, while using PLs alone as biosurfactants was the least efficient. In the following emulsion lipolysis experiments, BS/PL-9:4 outperformed other BS/PL mixtures in terms of enhancing the TG digestion extent. The degree of TG conversion and the desorption efficiency of interfacial material post-lipolysis correlated directly with the BS/PL ratio, decreasing as the PL proportion increased. In conclusion, this study highlights the crucial role of biliary PLs, alongside BSs, in replicating the physiological function of bile in intestinal lipolysis of emulsified TGs. Our results showed different contributions of PLs and BSs to lipolysis, strongly suggesting that any future in vitro studies aiming to simulate the human digestion conditions should take into account the impact of biliary PLs - not just BSs - to accurately mimic the physiological role of bile in intestinal lipolysis. This is particularly crucial given the fact that existing in vitro digestion protocols typically focus solely on applying specific concentrations and/or compositions of BSs to simulate the action of human bile during intestinal digestion, while overlooking the presence and concentration of biliary PLs under physiological gut conditions.

Aspartic protease supplementation enhancing the performance, carcass characteristics, nutrient digestibility and economic viability, without changing blood parameters and salivary cortisol of pigs.

Aiming to study the performance, carcass characteristics, nutrient digestibility, blood parameters, salivary cortisol levels, and economic viability of pigs administered aspartic protease, a total of 135 pigs were housed in pens in a randomized block design, divided into five treatments with nine replications. The experimental diets were positive control (PC), basic diet with a 5.0% reduction in protein and amino acid requirements; negative control (NC) with a 7.5% reduction in protein and amino acid requirements; NC + 100 g/mT of aspartic protease (NC100); NC + 150 g/mT of aspartic protease (NC150); and NC + 200 g/mT of neutral serine protease (NC200). The inclusion of protease, independently of the source and amount, increased the average daily weight gain (P < 0.05) of animals compared with the control treatments (PC and NC), improved feed conversion (P < 0.05) in early stages, and improved diet digestibility (P < 0.05) compared with the PC. Treatment with NC150 and NC200 resulted in greater carcass weights (P < 0.05) than treatment with the PC. NC100 led to a greater carcass yield than PC (P < 0.05), and NC150 resulted in a greater loin eye area than PC (P < 0.05). No differences (P > 0.05) in the blood parameters or salivary cortisol levels were found. Regarding economic viability, proteases increased the profitability, with NC150 leading to the best results. Thus, the use of aspartic proteases is recommended to improve performance and further facilitate pork production.

Standardized ileal digestibility of amino acids in Chinese fermented soybean meal from different sources fed to mid and late-gestating sows.

We determined apparent ileal digestibility (AID) and standardized ileal digestibility (SID) values of crude protein (CP) and amino acids (AA) in fermented soybean meal from five different sources (FSBM 1 to 5) in China when fed to mid and late-gestating sows. Twenty-four parity four sows (12 at 30 d in gestation and 12 at 80 d in gestation) were fitted with a T-cannula in the distal ileum and used in this experiment. Sows were randomly assigned to a replicated 6 × 3 Youden square design including six diets and three periods. Six diets were provided for sows in mid and late gestation, including a nitrogen-free diet and five test diets containing 26% FSBM from different sources. Results showed that there were differences in AID and SID of CP among the different FSBM samples, but no differences between sow physiological stages were observed. Specifically, when mid-gestating sows were fed FSBM 2, the AID of CP was the lowest, whereas FSBM 3 exhibited a greater AID of CP when compared to the other FSBM samples (P < 0.01). Furthermore, during late gestation, FSBM 3 consistently had greater SID of CP when compared to other FSBM samples (P < 0.01). The ileal digestibility of most AA varied with different FSBM samples. In both mid and late gestation, differences (P < 0.05) were observed for AID of lysine, tryptophan, histidine, and arginine across different FSBM samples. Similarly, the AID of dispensable AA (cysteine, glutamine, and serine) also exhibited differences (P < 0.05) across different FSBM samples in both mid and late-gestating sows. For mid-gestating sows, SID differences relating to lysine, phenylalanine, tryptophan, threonine, and arginine were observed among different diets (P < 0.05). In late-gestating sows, SID values for lysine, tryptophan, leucine, and arginine differed across diets (P < 0.05). Furthermore, the ileal digestibility of some dispensable AA was influenced by physiological stage, as evidenced by greater AID and SID values for glycine, glutamine, cysteine, and serine in late-gestating sows when compared to mid-gestating sows (P < 0.01). In summary, our study determined AA ileal digestibility of different FSBM fed to mid and late-gestating sows. We observed that the AA ileal digestibility differed among five FSBM samples, but the physiological stage of sows did not affect the ileal digestibility of CP and most AA. Additionally, when formulating diets for sows, it is crucial to consider the nutritional value differences of FSBM.

Fermented soybean meal (FSBM) is obtained from the microbial fermentation of soybean meal, which reduces anti-nutritional factor levels and enhances other nutrient content. Substituting soybean meal with FSBM in piglet and growing pig diets improves nutrient digestibility. However, its nutritional value for sows remains unclear. Therefore, five sources of FSBM were fed to sows in mid and late gestation to evaluate apparent ileal digestibility (AID) and standardized ileal digestibility (SID) values of amino acids (AA). We found that different FSBM samples impacted the SID value of AA when fed to gestating sows. Additionally, sow physiological stage influenced the SID of some dispensable AA. These findings provide valuable insights into the incorporation of FSBM into sow diets.

Effects of dietary forage neutral detergent fiber and rumen degradable starch ratios on chewing activity, ruminal fermentation, ruminal microbes and nutrient digestibility of Hu sheep fed a pelleted total mixed ration.

Pelleted total mixed ration (P-TMR) feeding, which has become a common practice in providing nutrition for fattening sheep, requires careful consideration of the balance between forage neutral detergent fiber (FNDF) and rumen degradable starch (RDS) to maintain proper rumen functions. The present study aimed to investigate the effects of the dietary FNDF/RDS ratio (FRR) on chewing activity, ruminal fermentation, ruminal microbes, and nutrient digestibility in Hu sheep fed a P-TMR diet. This study utilized eight ruminally cannulated male Hu sheep, following a 4 × 4 Latin square design with 31 d each period. Diets consisted of four FRR levels: 1.0 (high FNDF/RDS ratio, HFRR), 0.8 (middle high FNDF/RDS ratio, MHFRR), 0.6 (middle low FNDF/RDS ratio, MLFRR), and 0.4 (low FNDF/RDS ratio, LFRR). Reducing the dietary FRR levels resulted in a linear decrease in ruminal minimum pH and mean pH, while linearly increasing the duration and area of pH below 5.8 and 5.6, as well as the acidosis index. Sheep in the HFRR and MHFRR groups did not experience subacute ruminal acidosis (SARA), whereas sheep in another two groups did. The concentration of total volatile fatty acid and the molar ratios of propionate and valerate, as well as the concentrate of lactate in the rumen linearly increased with reducing dietary FRR, while the molar ratio of acetate and acetate to propionate ratio linearly decreased. The degradability of NDF and ADF for alfalfa hay has a quadratic response with reducing the dietary FRR. The apparent digestibility of dry matter, organic matter, neutral detergent fiber, and acid detergent fiber linearly decreased when the dietary FRR was reduced. In addition, reducing the dietary FRR caused a linear decrease in OTUs, Chao1, and Ace index of ruminal microflora. Reducing FRR in the diet increased the percentage of reads assigned as Firmicutes, but it decreased the percentage of reads assigned as Bacteroidetes in the rumen. At genus level, the percentage of reads assigned as Prevotella, Ruminococcus, Succinivibrio, and Butyrivibrio linearly decreased when the dietary FRR was reduced. The results of this study demonstrate that the dietary FRR of 0.8 is crucial in preventing the onset of SARA and promotes an enhanced richness of ruminal microbes and also improves fiber digestibility, which is a recommended dietary FRR reference when formulating P-TMR diets for sheep.

Forage neutral detergent fiber (FNDF) and rumen degradable starch (RDS) are key components of carbohydrates in the diet for ruminants, which would reflect saliva secretion and the acid production potential of feed. However, appropriate FNDF to RDS ratios (FRR) applicable to ruminants under the condition of pelleted total mixed ration (P-TMR) feeding have not been reported. In this study, we investigated the effects of the dietary FRR on chewing activity, ruminal fermentation, ruminal microbial communities, and nutrient digestibility of Hu sheep under P-TMR feeding. The results indicate that reducing dietary FRR levels would induce acidosis in sheep, which negatively affected fiber utilization and ruminal bacterial communities. The FRR of 0.8 was a recommended dietary FRR when formulating a P-TMR diet for fattening sheep, as indicated by decreased ruminal acidosis risk and increased richness of ruminal microbes in the rumen as well as nutrient digestibility.

The inclusion of companion forages in the diet alongside perennial ryegrass increased dry matter intake and organic matter digestibility in sheep.

The inclusion of companion forages in the diet of ruminant animals is gaining popularity in temperate regions due to observed improvements in animal performance. The aim of this study was to assess the effect of diet type on DM intake (DMI) and organic matter digestibility (OMD) in sheep. Furthermore, the effect of sward type on diet nutritive quality was investigated. Five dietary treatments were investigated using a 5 × 5 Latin square design experiment: Perennial ryegrass (Lolium perenne L.; PRG) only or PRG plus white clover (Trifolium repens L.;PRG + WC), red clover (Trifolium pratense L.; PRG + RC), chicory (Chicorium intybus L.; PRG + Chic) or plantain (Plantago lanceolata L.; PRG + Plan) at a ratio of 75% PRG and 25% of the respective companion forage and 100% PRG for the grass only treatment on a DM basis. Twenty Belclare castrated male (wether) sheep were housed in metabolism crates across five feeding periods. Individual DMI and faecal output were recorded daily and digestibility parameters were subsequently calculated. Results show that the inclusion of any companion forage increased DMI (kg/day DM) which ranged from 1.55 ± 0.038 (PRG) to 1.76 ± 0.038 (PRG + Chic) (P < 0.001). The PRG + WC (825 ± 1.1), PRG + RC (823 ± 1.1) and PRG + Chic (826 ± 1.1) diets had a greater in vitro OMD (g/kg DM) when compared to PRG (819 ± 1.1) or PRG + Plan (816 ± 1.1) (P < 0.001). Furthermore, the PRG + Chic (830 ± 2.9) diet had a greater in vivo OMD (g/kg DM) (P < 0.01) when compared to the PRG, PRG + RC, and PRG + Plan diets. Regression analysis showed that in vitro estimates moderately reflected in vivo measurements (r2 = 0.61). The inclusion of any companion forage increased dietary CP content and reduced the proportion of NDF in the diet. Crude protein concentration increased by an average of 16.5 g/kg DM and NDF content was reduced by 25.3 g/kg DM, on average, with companion forage inclusion (P < 0.001). Results suggest that binary sward mixtures benefit pasture-based sheep production systems, boosting sward quality, aiding increased DM intakes of a more digestible diet in the summer period.

In vitro simulated saliva, gastric, and intestinal digestion followed by faecal fermentation reveals a potential modulatory activity of Epimedium on human gut microbiota.

Herba Epimedii, known for its rich array of bioactive ingredients and widespread use in ethnopharmacological practices, still lacks a comprehensive understanding of its gastrointestinal biotransformation. In this study, we qualitatively explored the dynamic changes in Epimedium sagittatum components during in vitro simulated digestions, with a quantitative focus on its five major flavonoids. Notably, significant metabolism of E. sagittatum constituents occurred in the simulated small intestinal fluid and colonic fermentation stages, yielding various low molecular weight metabolites. Flavonoids like kaempferol glycosides were fully metabolized in the simulated intestinal fluid, while hyperoside digestion occurred during simulated colon digestion. Colonic fermentation led to the production of two known bioactive isoflavones, genistein, and daidzein. The content and bioaccessibility of the five major epimedium flavonoids-icariin, epimedin A, epimedin B, epimedin C, and baohuoside I-significantly increased after intestinal digestion. During colon fermentation, these components gradually decreased but remained incompletely metabolized after 72 h. Faecal samples after E. sagittatum fermentation exhibited shift towards dominance by Lactobacillus (Firmicutes), Bifidobacterium (Actinobacteria), Streptococcus (Firmicutes), and Dialister (Firmicutes). These findings enhance our comprehension of diverse stages of Herba Epimedii constituents in the gut, suggesting that the primary constituents become bioaccessible in the colon, where new bioactive compounds may emerge.

Analysis of Protein Digestion and Absorption Using a Ussing Chamber to Simulate the Environment in the Digestive Tract.

The Ussing chamber is a tool for analyzing drug absorption. We investigated whether the Ussing chamber can be used to analyze the process from digestion to absorption of protein in the gastrointestinal tract. Mixtures containing infant formula, whole cow's milk, processed soy milk, enteral nutrition, or human breast milk, were placed in the apical membrane side equipped with Caco-2 cells. After the addition of first pepsin then pancreatin, samples from the apical and basal membranes were collected. Infant formula showed the highest digestibility and absorption rate. This may be attributed to the presence of whey protein, which is rapidly digested and absorbed. The digestion and absorption of human breast milk showed different results in each donor, suggesting that digestion and absorption may vary among individuals. We concluded that the Ussing chamber can continuously analyze the process from digestion to absorption of proteins in the gastrointestinal tract.

Determination of ileal endogenous nitrogen losses and true ileal nitrogen digestibility during non-steady-state conditions of the 15N-isotope dilution technique.

The aim was to determine ileal endogenous nitrogen losses (ENL) and true ileal N-digestibility (TD-N) under non-steady-state conditions of the 15N-isotope dilution technique (15N-IDT), using diets generating low and high ENL and compare results to those obtained under steady-state conditions. Twelve growing pigs (mean LW 22.4 kg) fitted with a post-valve T-caecum cannula were fed an enzyme-hydrolysed casein (EHC)-based diet or an EHC diet + 4% quebracho tannins (QT) and were labelled via continuous 15N-leucine i.v. infusion or twice daily oral 15N-leucine administration. Digesta were collected daily over three consecutive hours with blood plasma sampled on the four consecutive days after cessation of 15N-labelling. There was a significant effect of sampling day on the dilution factor. Endogenous N losses were significantly lower for the EHC than the EHC+QT diet (2.41 vs. 8.69 g/kg DMI), while no significant effect of sampling day was observed. The TD-N of the EHC+QT diet did not differ from the TD-N of the EHC diet (95.1 vs. 92.0%). A significant effect of sampling day was observed for TD-N with day 1 and 2, being higher than day 4. Non-steady-state conditions overestimated ENL by 25-28% as compared to 3 h collections in steady-state conditions, but the relative overestimation was similar for the EHC diet as for the EHC+QT diet. TD-N did not differ significantly compared to 12 h steady-state measurements, but comparison to 3 h steady-state measurements showed that non-steady-state conditions overestimated TD-N for the EHC+QT diet by 9%. However, on day 4 this overestimation disappeared. Using the 15N-IDT during non-steady-state conditions can provide valuable additional data on endogenous N losses and TD-N.

The standardized ileal digestible lysine-to-net energy ratio in the diets of sows to optimize milk nitrogen retention is dynamic during lactation.

Fifty-two multiparous sows (average parity 3.1 ±â€…0.9 and initial BW 245.6 ±â€…32.5 kg) were used to evaluate the effects of dietary standardized ileal digestible (SID) Lys-to-net energy (NE) ratios on nitrogen (N) utilization throughout a 24-d lactation period. Sows were randomly assigned to one of five isoenergetic feeding programs that provided equally spaced and increasing SID Lys-to-NE ratios between 2.79 and 5.50 g SID Lys/Mcal NE. The feeding programs were generated by blending the two extreme diets in varying proportions and were provided to sows immediately after farrowing (day 1) and until weaning at day 24 ±â€…1. Nitrogen balances were conducted between days 4 and 7, 12 and 15, and 20 and 23 ±â€…1 of lactation to represent weeks 1, 2, and 3, respectively, using total urine collection and fecal grab sampling. Contrast statements were used to determine the linear and quadratic effects of increasing Lys-to-NE ratios. Linear and quadratic broken-line and polynomial quadratic (QPM) models were used to determine the optimum dietary Lys-to-NE ratios for N retention in milk. The Bayesian information criterion was used to assess the best fit. Feeding program did not influence sow average daily feed intake (5.8 ±â€…0.1 kg), BW change (-8.2 ±â€…3.1 kg), or change in back fat thickness (-2.6 ±â€…0.7 mm) over the 24-d lactation period, but piglet average daily gain increased with dietary SID Lys-to-NE ratio (linear; P < 0.05). Sow N intake increased with increasing dietary Lys-to-NE ratio in weeks 2 and 3 (linear; P < 0.001). Whole-body N retention (N intake - N output in urine and feces) increased with increasing dietary Lys-to-NE ratio in all weeks (linear; P < 0.05). The N retention in milk tended to increase then decrease with increasing dietary Lys-to-NE ratio in weeks 1 and 2 (quadratic; P = 0.051 and P = 0.081) and the QPM showed optimal milk N retention at 4.28, 4.42, and 4.67 g Lys/Mcal NE for weeks 1, 2, and 3, respectively. Maternal N retention (N intake - N output in urine, feces, and milk) decreased and then increased in week 1 (quadratic; P < 0.01) and increased in weeks 2 and 3 (linear; P < 0.01) with increasing dietary Lys-to-NE ratio. Therefore, the SID Lys-to-NE ratio necessary to optimize milk N output is dynamic throughout lactation. A two-diet feeding program could be created to match optimal weekly or daily SID Lys-to-NE ratios, which could lead to improved piglet ADG and body weights at weaning.

Despite significant changes in nutrient and energy requirements as well as voluntary feed intake during lactation, sows are typically fed a single diet with a static nutrient and energy composition throughout the entire lactation period, which may not optimize milk output. Fifty-two sows were used to explore how various ratios of standardized ileal digestible (SID) Lys to net energy (NE) in lactating sow diets affect the growth of piglets and nitrogen utilization during a 24-d lactation period. Sows were randomly assigned to one of five feeding programs that contained equal amounts of energy and provided equally spaced and increasing Lys-to-NE ratios between 2.79 and 5.50 g SID Lys/Mcal NE immediately after farrowing. The dietary Lys-to-NE ratio did not influence sow daily feed intake, body weight change, or change in backfat thickness over the 24-d lactation period; however, piglet growth rate and body weight at weaning increased with increasing Lys-to-NE ratio. The SID Lys-to-NE ratio necessary to optimize milk nitrogen output was 4.28, 4.42, and 4.67 g SID Lys/Mcal NE during weeks one, two, and three of lactation, respectively. Therefore, it is possible to create a two-diet feeding program offering dynamic SID Lys-to-NE ratios as lactation progresses, which could lead to improved piglet average daily gain and body weights at weaning.

Synergistic digestibility effect by planktonic natural food and habitat renders high digestion efficiency in agastric aquatic consumers.

A digestibility enhancing effect of natural food on stomachless fish model (Cyprinus carpio) was verified by fluorogenic substrate assays of enzymatic activities in experimental pond carp gut flush and planktonic food over a full vegetative season. Then compared with size-matched conspecific grown artificially (tank carp) and an advanced omnivore species possessing true stomach (tilapia, Oreochromis niloticus). Results suggested activities of digestive enzymes (except amylolytic) were significantly higher in pond carp (p ≤ 0.05) than in the size-matched tank carp. Even compared to tilapia, pond carp appeared superior (p < 0.05; proteolytic or chitinolytic activities) or comparable (p > 0.05; phosphatase or cellulolytic activities). Amylolytic, chitinolytic, and phosphatases activities in pond carp gut significantly increased (p ≤ 0.01) over season. Several orders-of-magnitude higher enzymatic activities were detected in planktonic natural food than expressed in carp gut. Amino acid markers in planktonic food revealed a higher share of zooplankton (microcrustaceans), but not phytoplankton, synchronized with higher activities of complex polysaccharide-splitting enzymes (cellulolytic and chitinolytic) in fish gut. Periods of clear water phase low in chlorophyll-a and nutrients, but high in certain zooplankton (preferably cladocerans), may create a synergistic digestibility effect in pond carp. We conclude aquatic ecosystem components (natural food, water, microbiota) enhance fishes' hydrolyzing capabilities of C/N/P macromolecules and even their complex polymers such as cellulose, chitin, and maybe phytate (to be validated), to the extent that being stomachless is not an issue. Aquatic nutritional ecologists may consider that laboratory-based understandings of digestibility may underestimate digestion efficiency of free-ranging fish in ponds or lakes.

In vitro gastrointestinal simulated digestion of three plant proteins: determination of digestion rate, free amino acids and peptide contents.

Cassava protein (CP), barley protein (BP) and yellow pea protein (YPP) are important nutrient and integral constituent of staple in pet foods. It is known that the digestion of proteins directly influences their absorption and utilisation. In the present work, we performed in vitro simulated gastrointestinal digestion of three plant proteins as a staple for dog and cat food. The digestion rate of CP, BP and YPP in dog food was 56.33 ± 0.90%, 48.53 ± 0.91%, and 66.96 ± 0.37%, respectively, whereas the digestion rate of CP, BP, and YPP in cat food was 66.25 ± 0.72%, 43.42 ± 0.83%, and 58.05 ± 0.85%, respectively. Using SDS-polyacrylamide gel electrophoresis to determine the molecular weight (MW) of each protein and the products of their digestion, it was revealed that MW of digestion samples decreased, and MW during the small intestine phase was lower than that during the gastric phase. Peptide sequences of digested products were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and it was found that the total number of peptides in the small intestine digestion samples was higher than that in the gastric phase samples. The MW of peptides obtained from CP was within the range of 1000-1500 Da, while MW of peptides derived from BP and YPP was within the range of 400-2000 Da. In addition, free amino acids were mainly produced in the small intestine phase. Furthermore, the percentage of essential amino acids in the small intestine phase (63 ~ 82%) was higher than that in the gastric phase (37 ~ 63%). Taken together, these findings contribute to the current understanding of the utilisation of plant proteins in dog and cat foods and provide important insights into the selection and application of plant proteins as a staple in dog and cat foods.

Carbohydrates and protein digestive traits in beef cattle grazing fertilised or mixed tropical pasture.

This study was performed to investigate the nitrogen (N) and carbohydrate digestive traits of grazing heifers. The experiment was carried out at the Federal University of Lavras. The treatments were a Marandu palisadegrass (Urochloa brizantha [Syn, Brachiaria brizantha] Stapf. A. Rich. cv. Marandu) monoculture fertilised with 150 kg N/[ha ∙ year] (FP) or Marandu palisadegrass mixed pasture with forage peanut (MP). The pastures were grazed by six rumen-cannulated zebu heifers. A double cross-over design was used in four periods. Nutritive value, intake and apparent digestibility of forage, ruminal traits and kinetics and N balance were evaluated. Apparent total-tract digestibility of dry matter (DM) and neutral detergent fibre (NDF) were greater for FP than for MP. There was no effect in apparent total-tract digestibility of N. The estimated intestinal digestibility of nutrients was greater on MP than FP. Even though N intake and faecal N output were greater on MP than FP, there was no effect in urine N output. The N balance tended to be greater on MP than FP. The forage peanut, which contains condensed tannins, decreased ruminal fibre degradation, apparent digestibility and ruminal protein degradation, increased N flow from the rumen. Inclusion of forage peanut in the mixed pasture decreased the ruminal fibre degradability but increased N retention by the animals.

Ileal phosphorus digestibility of soybean meal for broiler chickens remains consistent across institutions in a collaborative study regardless of non-phytate phosphorus concentration in the pre-experimental starter diet.

The same experimental protocol was used in 4 institutions to evaluate the impact of non-phytate phosphorus (nPP) concentration in the starter diet on regression method-derived ileal P digestibility of soybean meal (SBM) during the subsequent grower phase. A total of 1,536 Ross 308 male broiler chickens on d 0 post hatching were allotted to 2 pre-experimental starter diets that contained 3.5 or 4.5 g nPP/kg (96 replicate cages per diet, 8 birds per cage) for 18 d. Subsequently, 576 birds from each starter diet were selected and allocated to 3 experimental semi-purified grower diets containing 400, 510, or 620 g SBM/kg (32 replicate cages per diet, 6 birds per cage) for 3 d until collection of ileal digesta. Statistical analysis was conducted as a randomized complete block design with the starter period as whole plot and the grower period as split-plot. The only significant 2-way interaction was between grower diet and experimental institution (P < 0.05) on BW gain and gain to feed ratio. The main effect of institution and grower diet impacted (P < 0.05) feed intake, the digestibility of DM, P, and calcium, and disappearance of inositol hexakisphosphate (InsP6) in the grower diets. Birds fed the 3.5 g nPP/kg starter diet had lower (P < 0.05) BW gain and feed intake during the grower period, but presented higher (P < 0.05) digestibility of P and disappearance of InsP6 compared with the birds that were fed the 4.5 g nPP/kg starter diet. Regression method-derived ileal P digestibility of SBM was determined to be 46 or 42% for the respective 3.5 or 4.5 g nPP/kg pre-experimental starter diet and was not affected by the nPP concentration or by the institution. In conclusion, the experimental protocol used in the current study resulted in similar estimates across multiple institutions and is thus endorsed for future application in studies that aim to expand the database of digestible P content in plant source feed ingredients.

Specific dynamic action: the energy cost of digestion or growth?

The physiological processes underlying the post-prandial rise in metabolic rate, most commonly known as the 'specific dynamic action' (SDA), remain debated and controversial. This Commentary examines the SDA response from two opposing hypotheses: (i) the classic interpretation, where the SDA represents the energy cost of digestion, versus (ii) the alternative view that much of the SDA represents the energy cost of growth. The traditional viewpoint implies that individuals with a reduced SDA should grow faster given the same caloric intake, but experimental evidence for this effect remains scarce and inconclusive. Alternatively, we suggest that the SDA reflects an organism's efficacy in allocating the ingested food to growth, emphasising the role of post-absorptive processes, particularly protein synthesis. Although both viewpoints recognise the trade-offs in energy allocation and the dynamic nature of energy distribution among physiological processes, we argue that equating the SDA with 'the energy cost of digestion' oversimplifies the complexities of energy use in relation to the SDA and growth. In many instances, a reduced SDA may reflect diminished nutrient absorption (e.g. due to lower digestive efficiency) rather than increased 'free' energy available for somatic growth. Considering these perspectives, we summarise evidence both for and against the opposing hypotheses with a focus on ectothermic vertebrates. We conclude by presenting a number of future directions for experiments that may clarify what the SDA is, and what it is not.

Hydrolysed poultry byproduct meal in extruded diets for cats.

Hydrolysed proteins have been shown to be potential ingredients in cat diets due to their high digestibility, presence of bioactive peptides, and relatively low antigenicity. The effects of the substitution of conventional low ash poultry byproduct meal (PBM) with hydrolysed poultry byproduct meal (HPM) as a protein source were evaluated in extruded cat diets. Five diets with similar nutrient contents were formulated: a control (CO) diet based on PBM and 4 diets with different inclusions of HPM (5%, 10%, 20%, and 30%, on an as-fed basis) replacing PBM as the protein source. The total tract apparent digestibility (CTTAD) of nutrients, faecal characteristics and microbial fermentation products, urine production and pH, nitrogen balance and urea renal excretion were evaluated using 30 healthy cats (15 males and 15 females; 4.18 ± 0.86 kg; 4.17 ± 1.38 years old), with 6 cats per diet in a complete randomised block design. When significant differences were found with the F test, the effects were evaluated by polynomial contrasts according to HPM inclusion (p < 0.05). The CTTADs of DM (89 ± 0.41%), CP (90 ± 0.36%), fat (93 ± 0.41%) and gross energy (90 ± 0.33%) were similar among treatments (p > 0.05). The faecal production, score, short-chain fatty acids and ammonia concentration were similar among treatments (p > 0.05). Isobutyric, isovaleric, valeric, and total branched-chain fatty acid contents increased quadratically (p < 0.05), with the highest level in the faeces of cats fed the diet with 20% HPM. Lactate concentration in faeces increased linearly with the inclusion of HPM (p < 0.05). Urine characteristics and urea renal excretion did not differ among treatments (p > 0.05). At 10% inclusion, HPM tended to increase the nitrogen retention of cats (p = 0.083), which may reflect the higher tryptophan, methionine, lysine, and available lysine contents of HPM in comparison to PBM. The inclusion of up to 30% HPM can be considered in cat formulations without affecting nutrient digestibility or faecal and urine characteristics. HPM tended to increase nitrogen retention and increased branched-chain fatty acids in faeces, aspects which deserves further studies.

Characterization of ruminal degradation, intestinal digestion and total true nutrient supply to dairy cows from feedstocks and coproducts from Canola bio-oil processing: Impact by source origin.

The objective of this study was to characterize ruminal degradation, intestinal digestion and total true nutrient supply to dairy cows from canola feedstock (canola seeds) and coproducts (meal and pellets) from bio-oil processing which were impacted by source origin. The feedstocks and coproducts (mash, pellet) were randomly collected from five different bio-oil processing plants with five different batches of samples in each bio-processing plant in Canada (CA) and China (CH). In situ rumen degradation kinetics were determined using four fistulated Holstein cows with incubation times at 0, 2, 4, 8, 12, 24 and 48 h. Intestinal digestions were determined using the three-step in vitro method with preincubation at 12 h. The DVE/OEB and National Research Council systems were applied to evaluate the truly absorbable nutrient supply to dairy cows and feed milk values (FMVs). The results showed that in situ undegradable fractions (U) (p = 0.025) were higher in CA meals, and potentially degradable fraction of D was higher (p = 0.016) in CH meals. CH meals had higher total digestible dry matter (TDDM, p = 0.018) and intestinal digestibility of protein (dIDP, p = 0.016). Canola meals from CA had lower MREE (microbial protein synthesized in the rumen based on available rumen degradable protein; p = 0.011) and DVME (rumen synthesized microbial protein digested in the small intestine; p = 0.011) and had higher ECP (endogenous protein in the small intestine, p = 0.001) and absorbed endogenous crude protein (truly absorbed ECP in the small intestine) than CH (p = 0.001). The FMV evaluated based on the metabolic protein and net energy showed no differences between CA and CH in both coproducts and feedstocks.

Intake, digestibility, energy and nitrogen utilisation, and enteric methane emission in Holstein and Girolando-F1 cows during the transition period.

This study aimed to evaluate intake, energy and nitrogen balance as well as methane emission in Holstein and ½ Holstein ½ Gyr (Girolando-F1) cows during the transition period. Twenty-four cows (12 Holstein and 12 Girolando-F1) were used to evaluate feed intake, apparent digestibility, heat production and methane emission, carried out in two periods: from 28 to 19 days pre-calving and from 15 to 23 days post-calving. A completely randomised design was used and data were analysed by ANOVA within periods (pre- and post-calving) considering the main effect of genetic groups. Girolando-F1cows presented greater body condition score (BCS) compared with Holstein. During pre-calving, there were no differences between genetic groups, except for highest heat production per kilogram of metabolic body weight for Holstein cows. After calving, Holstein cows had greater intake of DM, nitrogen, NDF per kg of BW and produced more heat per kg of metabolic body weight. Holstein cows yielded more milk and fat-corrected milk (FCM4%) compared with Girolando-F1 cows. Holstein cows presented higher methane emission per unit of BW and of metabolic weight. Emissions of enteric methane per kilogram of milk and per kilogram of FCM4% tended to be lower for Holstein compared with Girolando-F1 cows. Nitrogen and energy retention were similar for both Holstein and Girolando-F1 at pre- and post-calving. Despite differences in BCS, DMI, and milk yield, Girolando-F1 and Holstein cows present overall similar energy efficiency, albeit Holstein cows tended to present less methane emission per kg of eligible product (milk).