Jingjing Xie

This study aimed to establish predictive equations for digestible energy (DE) and metabolizable energy (ME) of feed ingredients using a novel computer-controlled simulated digestion system (CCSDS) and validate the additivity of predicted energy values in complete diets for growing pigs. An in vivo experiment was conducted to determine the DE and ME of 30 experimental diets. A total of 60 barrows (initial BW of 37.3 ± 4.7 kg) were used, divided into two replicate blocks of 30 pigs each. Within each block, a 30 × 3 Youden square design was implemented across three experimental periods. Two pigs were allocated per diet during each period, resulting in six replicates per diet. Experimental diets included 20 feed ingredients, and 10 validation diets were formulated with the above feed ingredients to assess energy additivity and accuracy. The in vitro digestible energy (IVDE) was determined using CCSDS with five replicates for each diet. Strong correlations were observed between IVDE and in vivo DE (DE = 1.001 × IVDE + 180, R² = 0.85, RSD = 310 kcal/kg of DM, P < 0.01) and ME (ME = 1.015 × IVDE—29, R² = 0.89, RSD = 254 kcal/kg of DM, P < 0.01), with predicted values closely aligning with determined values across all feed ingredients. The mean IVDE: DE and IVDE: ME were approximately 0.95 and 0.99, respectively, highlighting the high predictive accuracy of CCSDS. Validation diets demonstrated consistent energy additivity. Single sample t-tests revealed no difference was observed between predicted and determined DE values in eight out of ten diets, and between predicted and determined ME values in nine out of ten diets. In conclusion, these findings underscore the utility of CCSDS as a cost-effective and reliable alternative to in vivo methods, offering significant potential for precise energy assessment in swine feed formulation. Determining the available energy content of feed for animals is critical; however, in vivo methods are time-consuming, costly, and technically complex. This study evaluated an automated computer-controlled simulated digestion system (CCSDS), designed to simulate the digestive processes of growing pigs under laboratory conditions. The system was used to analyze 20 common pig feed ingredients. The results obtained from the CCSDS were subsequently compared with data derived from in vivo experiments. A strong agreement was observed between the two methods, indicating that the CCSDS can accurately predict the available energy content of feeds for growing pigs. Additionally, when these predicted values were used to calculate the available energy in complete mixed diets, the results demonstrated consistent accuracy. In conclusion, the CCSDS presents a rapid, cost-effective, and reliable alternative to in vivo trials for determining the available energy of feed. This tool can assist feed producers in formulating more precise diets for growing pigs, thereby enhancing the efficiency of animal production.

The objective of this study was to evaluate the effect of coating on the recovery rate (RR) of phytase activity during the steam conditioning-pelleting (SCP) process. A split-plot design was employed, with phytases assigned to the main plot and two conditioning temperatures (75 or 85 °C) assigned to the subplot. The whole plot was repeated four times. In Exp. 1, six phytases were analyzed, including an uncoated phytase (NP) NP1 (NP1), two coated phytases (CP) CP1 and CP2 derived from NP1, and three commercial phytases (MP) MP1-MP3. In Exp. 2, coating technology was refined based on the results of Exp. 1, and nine phytases were analyzed, including an NP2, five coated phytases CP3-CP7 derived from NP2, and three commercial phytases MP4-MP6. Phytase activity after the steam-conditioning, pelleting, and cooling process was analyzed, and the RR of phytase activity was calculated for each process. In Exp. 1, significant interactions between phytase and conditioning temperature on the RR of phytase activity were observed (P < 0.05). The RR of CP1 and CP2 did not differ from that of NP1. Commercial phytase MP3 exhibited a lower RR than the other four phytases when conditioned at 75 °C (P < 0.05). Except for MP3, the RR of phytases decreased as the conditioning temperature increased (P < 0.05). In Exp. 2, the RR of phytase decreased as the conditioning temperature increased from 75 to 85 °C (P < 0.05). Compared with NP2, the RR increased, and the loss rate of activity for all five coated phytase (CP3-CP7) decreased after the conditioning process (P < 0.05). Commercial phytase MP4 and MP6 had comparable RR to NP2, while MP5 exhibited a comparable RR to CP3-CP7. In conclusion, the coating technology used in Exp. 1 did not increase the RR of phytase during the pelleting process, whereas the improved coating process employed in Exp. 2 effectively increased the thermostability of phytase.

Net energy (NE) is most precise measure of dietary energy for broilers, but its accurate determination requires a reliable respiratory calorimeter. This study developed a computer-controlled closed-circuit respiratory calorimeter to measure oxygen (O2) consumption, carbon dioxide (CO2) production, and energy utilization in broilers, and evaluated its accuracy and repeatability. Three groups of six closed-circuit calorimeters were randomly assigned to burn 100, 150, or 200 g of ethanol (purity ≥ 99.7%) to assess the accuracy of O2 usage and CO2 production. Subsequently, three groups of six calorimeters, each containing three male Arbor Acres broilers (body weight [BW] = 948 ± 14 g) as one experimental unit were used to test the repeatability of the chamber environment control, growth performance, and the determination of dietary energy utilization in broilers. Sensors automatically logged temperature, humidity, O2 and CO2 concentrations, O2 consumption, BW, and average daily gain (ADG). Data analysis was conducted using SAS 9.4 using the MEANS, GLM, and REG procedures. The relative ratios of actual O2 consumption and CO2 production to theoretical values (from complete ethanol combustion) ranged from 100.4% to 101.3% (P = 0.326), and 102.7% to 102.8% (P = 0.981), respectively, with all CV below 1.53%, demonstrating the system’s accuracy and precision in quantifying respiratory gas exchange. The CV of inter-group (CVinter-group) for temperature, humidity, and O2 concentration were 0.08% (P = 0.664), 1.14% (P = 0.726), and 0.09% (P = 0.203), respectively. The CVinter-group for ADG, average daily feed intake (ADFI), and feed conversion ratio were 3.09% (P = 0.551), 2.24% (P = 0.580), and 2.11% (P = 0.364), respectively. The CVinter-group for O2 consumption and CO2 production were 1.21% (P = 0.903) and 1.86% (P = 0.758), respectively, and both factors were linearly related to BW0.70 and ADFI (R2 ≥ 0.889, P < 0.010). The CVinter-group for apparent metabolizable energy, total heat production, heat increment, NE, retained energy, NE deposited as protein or as fat ranged from 0.21% to 3.19% (0.236 ≤ P ≤ 0.903). These results demonstrate the system’s high repeatability and precision in maintaining environment conditions and monitoring growth performance and energy partitioning in broilers. Thus, this system is a valuable tool for accurately evaluating energy utilization in broilers.

Recent studies have discovered that wheat bran could stimulate digestive tract development, modulate intestinal microbiota, and improve the digestibility of fibrous ingredients in broilers. Wheat bran varies greatly in its chemical constituents. The objective of this study is to investigate how different types of wheat bran influence growth performance, nutrient digestion, and gut health in broiler chickens. Eight types of wheat bran were sampled and analyzed for nine constituents. A principal component analysis demonstrated that the wheat bran could be clustered into three groups based on the first principal component, namely low-fiber (LF), medium-fiber (MF), and high-fiber (HF) wheat bran. Wheat bran from the LF, MF, and HF groups significantly differed in terms of the contents of NDF, acid detergent fiber (ADF), hemicellulose, in vitro digestible energy (IVDE), crude fat, and ash (p < 0.05). A total of 324 seven-day-old broiler chicks were grouped into six body weight blocks. Each block of birds was randomly divided into six treatments, fed either a corn–soybean meal basal diet or five experimental diets, including 3% wheat bran from the LF, MF, and HF groups, until d 21. The feed/gain ratio was increased, and the coefficients of dry matter (DM, p = 0.001), gross energy (GE, p = 0.005) digestion, energy (p = 0.039), and CP (p = 0.051) retention were reduced in the birds that were fed 3% HF wheat bran. In contrast, in the birds fed 3% LF wheat bran, the coefficients of nutrient digestion and retention of energy and CP were not affected, but the CP (p = 0.009) and the NDF (p = 0.059) digestion ability were increased when switched to the same diet. In the cecal digesta, Barnesiella was enriched in the birds from the LF group, while Lachnospiracea was enriched in the birds from the MF group. Adding a moderate amount of wheat bran from the LF group could promote protein and fiber digestion and increase the abundance of Barnesiella in broilers.

Phytase activity can be impaired during pelleting because of extreme thermal conditions. This study investigated the effects of dose and source of phytase on phytase activity during the conditioning, pelleting, and cooling process. A split-plot design was used in two experiments, with five phytase doses (Exp. 1; 7560, 14310, 33830, 43590 and 61500 FTU/kg) or eight phytase sources (Exp. 2) as the main plot and steam conditioning temperatures (Exp. 1 and 2; 75 and 85 °C) as the subplot. Each treatment processed four batches, one batch per replicate. The results of Exp. 1 showed phytase dose in diets had no effect (p > 0.05) on the recovery rate of phytase activity after the conditioning, pelleting, or cooling process. The recovery rate of phytase activity in each process was higher (p < 0.05) at 75 °C than that at 85 °C for both Exp. 1 and 2. The phytase source significantly affected (p < 0.05) the recovery rate of phytase activity and had varied appearances of structure. In conclusion, the structure, phytase activity, and phytase recovery after steam conditioning–pelleting significantly varied across sources, but the stability of phytase was not affected by dose.

This experiment evaluated the difference between computer-controlled simulated digestion and in vivo stomach-small intestinal or large intestinal digestion for growing pigs. Five diets including a corn-soybean meal basal diet and four experimental diets with rapeseed meal (RSM), cottonseed meal (CSM), sunflower meal (SFM), or peanut meal (PNM) were assigned to each group of five barrows installed terminal ileal cannula or distal cecal cannula in a 5×5 Latin square design. Ileal digesta and feces were collected for the determination of digestibility of dry matter (DM) and gross energy (GE) as well as digestible energy (DE) at terminal ileum and total tract. The large intestinal digestibility and DE were calculated by the difference between measurements obtained at the terminal ileum and those obtained from total tract. In vitro stomach-small intestinal digestibility and DE for diets and plant protein meals were determined by stomach-small intestinal digestion in a computer-controlled simulated digestion system (CCSDS). The in vitro large intestinal digestibility and DE of diets were determined in a CCSDS using ileal digesta and enzymes extracted from cecal digesta of pigs. The in vitro large intestinal digestibility and DE of four plant protein meals were determined by the difference between stomach-small intestinal and total tract digestion in the CCSDS. For the experimental diets, the in vitro ileal digestibility and DE were not different from corresponding in vivo values in basal diet and PNM diet, but greater than corresponding in vivo values for diets with RSM, CSM and SFM (P < 0.05). No difference was observed between in vitro and in vivo large intestinal digestibility and DE in five diets. For the feed ingredients, the in vitro ileal digestibility and DE did not differ from corresponding in vivo ileal values in RSM and PNM but were greater than the in vivo ileal values in CSM and SFM (P < 0.05). The in vitro large intestinal GE digestibility and DE were not different from in vivo large intestinal values in RSM, CSM, and PNM, but lower than in vivo large intestinal values in SFM. This finding may relate to the higher fiber content of plant protein meals resulting in shorter digestion time of in vivo stomach-small intestine thus lower digestibility compared to in vitro, indicating it is necessary to optimize in vitro stomach-small intestinal digestion time.