Nutrient Digestibility Research Articles

Effects of Dietary Supplementation of Quillaja Saponin or Phytase on the Growth Performance, Nutrient Digestibility, Faecal Gas Emissions, and Carcass Grade in Growing-Finishing Pigs.

This experiment aimed to evaluate the effects of low doses of Quillaja saponin (QS) or phytase (PHY) on growth performance, nutrient digestibility, faecal gas emissions, and carcass grade in growing-finishing pigs. A total of 72 pigs (Landrace × Yorkshire × Duroc), each weighing 25.82 ± 1.68 kg, were selected and randomly assigned to three treatment groups. Each group had six replicates, with four pigs per pen, and the allocation was based on the four initial body weight and sex of the pigs. They were randomly divided into the following three diet groups: the basal diet as a control (CON) group, the basal diet + 0.02% PHY; and the basal diet + 0.01% QS. The experiment period lasted for 110 days. The results of adding 0.01% QS to the basal diet of pigs show that it can significantly increase the body weight (BW) of growing-finishing pigs on the 110th day (p < 0.05). QS can significantly increase the average daily weight gain (ADG) on Days 80-110 of the experiment (p < 0.05). QS can significantly increase the total average daily weight gain (TADG) of growing-finishing pigs during the entire experimental period (p < 0.05) and has a tendency to improve the average daily feed intake and feed conversion rate during the entire experimental period. However, QS has no significant effect on pig nutrient digestibility and carcass grade. In addition, we also found that QS has a tendency to reduce carbon dioxide emissions. However, adding 0.02% PHY to the basal diet of growing-finishing pigs can only increase the TADG during the entire experimental period. Throughout the experiment, adding PHY to the diet had no significant impact on the nutrient digestibility, faecal gas emissions, and carcass grade of growing-finishing pigs. In summary, adding QS to feed can significantly improve the growth performance of growing-finishing pigs, and has a tendency to improve faecal gas emissions. PHY can only improve the growth performance of growing-finishing pigs.

Effects of replacing soybean meal with enzymolysis-fermentation compound protein feed on growth performance, apparent digestibility of nutrients, carcass traits, and meat quality in growing-finishing pigs

BackgroundAddressing the shortage of high-quality protein resources, this study was conducted to investigate the effects of replacing soybean meal (SBM) with different levels of enzymolysis-fermentation compound protein feed (EFCP) in the diets of growing-finishing pigs, focusing on growth performance, nutrients digestibility, carcass traits, and meat quality.MethodsSixty DLY (Duroc × Landrace × Yorkshire) pigs with an initial body weight of 42.76 ± 2.05 kg were assigned to 5 dietary treatments in a 2 × 2 + 1 factorial design. These dietary treatments included a corn-soybean meal diet (CON), untreated compound protein feed (UCP) substitution 50% (U50) and 100% SBM (U100) diets, and EFCP substitution 50% (EF50) and 100% SBM (EF100) diets. Each treatment had 6 pens (replicates) with 2 pigs per pen, and the experiment lasted 58 d, divided into phase I (1–28 d) and phase II (29–58 d). Following phase I, only the CON, U50, and EF50 groups were continued for phase II, each with 5 replicate pens. On d 59, a total of 15 pigs (1 pig/pen, 5 pens/treatment) were euthanized.ResultsDuring phase I, the EF50 group had a higher average daily gain (ADG) in pigs (P < 0.05) compared to the CON group, whereas the U50 group did not have a significant difference. As the substitution ratio of UCP and EFCP increased in phase I, there was a noticeable reduction in the final body weight and ADG (P < 0.05), along with an increase in the feed-to-gain ratio (F/G) (P < 0.05). In phase II, there were no significant differences in growth performance among the treatment groups, but EF50 increased the apparent digestibility of several nutrients (including dry matter, crude protein, crude fiber, acid detergent fiber, ash, gross energy) compared to U50. The EF50 group also exhibited significantly higher serum levels of neuropeptide Y and ghrelin compared to the CON and U50 groups (P < 0.05). Moreover, the EF50 group had higher carcass weight and carcass length than those in the CON and U50 groups (P < 0.05), with no significant difference in meat quality.ConclusionsThe study findings suggest that replacing 50% SBM with EFCP during the growing-finishing period can improve the growth performance, nutrient digestibility, and carcass traits of pigs without compromising meat quality. This research offers valuable insights into the modification of unconventional plant protein meals and developing alternatives to SBM.

Mass Transfer Resistance and Reaction Rate Kinetics for Carbohydrate Digestion with Cell Wall Degradation by Cellulase.

This paper introduces an enzymatic approach to estimate internal mass-transfer resistances during food digestion studies. Cellulase has been used to degrade starch cell walls (where cellulose is a significant component) and reduce the internal mass-transfer resistance, so that the starch granules are released and hydrolysed by amylase, increasing the starch hydrolysis rates, as a technique for measuring the internal mass-transfer resistance of cell walls. The estimated internal mass-transfer resistances for granular starch hydrolysis in a beaker and stirrer system for simulating the food digestion range from 2.2 × 107 m-1 s at a stirrer speed of 100 rpm to 6.6 × 107 m-1 s at 200 rpm. The reaction rate constants for cellulase-treated starch are about three to eight times as great as those for starch powder. The beaker and stirrer system provides an in vitro model to quantitatively understand external mass-transfer resistance and compare mass-transfer and reaction rate kinetics in starch hydrolysis during food digestion. Particle size analysis indicates that starch cell wall degradation reduces starch granule adhesion (compared with soaked starch samples), though the primary particle sizes are similar, and increases the interfacial surface area, reducing internal mass-transfer resistance and overall mass-transfer resistance. Dimensional analysis (such as the Damköhler numbers, Da, 0.3-0.5) from this in vitro system shows that mass-transfer rates are greater than reaction rates. At the same time, SEM (scanning electron microscopy) images of starch particles indicate significant morphology changes due to the cell wall degradation.

Microbial community profiling in intestinal tract of indigenous chickens from different villages

Village chickens (Gallus gallus domesticus) are commonly reared in rural households of South Africa and other developing countries. They play a vital role as a primary source of protein through the provision of meat and eggs. The chicken gut microbiota plays an important role in chicken’s immune system, its health, physiological development of the gut, digestion of food, nutrient absorption and productivity. Thus, it is imperative to critically investigate the chicken microbial composition in order to develop effective disease control measures and increase production. In this present study, microbial DNA was isolated from 34 non-descript mixed gender matured village chickens’ intestinal contents followed by high throughput Illumina sequencing targeting 16S rRNA gene. Senwamokgope village had the largest microbiota composition as compared to Itieleni and Thakgalang villages. Overall, Firmicutes (74%) was the most abundant phylum observed, followed by Proteobacteria (8%), Actinobateria (5%), and Bacteroidota (3%). At the genus level, Lactobacillus was the dominant bacteria. Other genera found included Sphingomonas (7%), Cutibacterium (4%), and Clostridium_sensu_stricto_1 (2%). The richness of female intestinal microbiota was higher compared to the male microbiota. The findings of this study provide baseline information that can assist to better understand the chicken gut microbiota and its interaction with diseases and parasites.

Production Performance, Nutrient Digestibility, Mortality and Cost of Production of the Layer Chicken on Dietary Supplementation of Aloe Vera (Aloe barbadensis)

Production Performance, Nutrient Digestibility, Mortality and Cost of Production of the Layer Chicken on Dietary Supplementation of Aloe Vera (Aloe barbadensis)

In Vitro Efficacy of Formulated Protected Fat from Used Cooking Oil (UCO) on Gas Production, Nutrient Digestibility and Rumen Fermentation

This study was designed to determine in vitro gas production, nutrients digestibility, and rumen fermentation products of supplementary formulated dietary protected fat (PF) from used cooking oil (UCO). The dietary fat treatment was formulated from used cooking oil protected fat (UCOPF) and compared with other four dietary fat treatment were used cooking oil (UCO) and palm olein (PO which are active fat; palm olein protected fat (POPF) and commercial protected fat (CPF) which are inert fat added at 12 mg of dry matter (DM) in the 200 mg of basal diet (70:30 roughage to concentrate ratio). Control group contain basal diet without dietary fat supplement. Supplementation of dietary fat had no effect on gas production, pH, organic matter digestibility (OMD) and volatile fatty acid volatile fatty acids (VFA). The addition of fat in the form of oil and protected fat to in vitro setups up to 12 mg did not adversely affect the characteristics of rumen fermentation suggests that fat has a smaller impact on production of gas, digestibility of nutrients, and rumen fermentation products.

Effects of Partial Replacement of Corn Grains With Mango Seed Kernel on Nutrient Digestibility, Blood Metabolites and Rumen Parameters of Growing Calves.

Fruit by-products are a sustainable and cost-effective alternative to traditional grain feed for livestock. One of the most important by-products is mango seed kernel (MSK), which can be used as a valuable energy source for feeding growing calves in the tropical and subtropical productive regions of the world. This study investigated the effect of replacing corn grains (CGs) with MSK on intake, nutrient digestibility, blood metabolites and rumen parameters. Eighteen growing male Friesian calves (200 ± 6.55 kg of body weight and 9-11 months old) were randomly assigned to three treatment groups. Three concentrate feed mixtures were formulated such that MSK replaced CG at 0%, 25% and 50%. Dry matter intake was unaffected, whereas dry matter, organic matter and fibre digestibility increased linearly (p < 0.05) with increased inclusion of MSK. Ruminal pH (p = 0.053) and total volatile fatty acid (VFA) concentration (p = 0.041) increased linearly. There was a linear decrease in cholesterol (p = 0.029) and AST (p = 0.028) levels in the blood of calves. In conclusion, this study demonstrated the positive effect of replacing 50% of CG with MSK on rumen parameters, including a higher ruminal pH and total VFA concentration, alongside higher nutrient digestibility. The dietary inclusion of mango seed can serve as a valuable and sustainable dietary component for growing calves.

Towards more sustainable, nutritious, and affordable plant‐based milk alternatives: A critical review

AbstractThe consumer market has seen a surge in various types of plant‐based milk alternatives (PBMAs), driven by factors such as sustainability, ethics, and the availability of diverse options. However, the global adoption of PBMAs is still hindered by potential nutritional concerns and cost‐ineffectiveness. It is therefore paramount to understand the status and challenges of these alternatives, encompassing production, stabilization strategies, nutrition and health, digestion, and environmental impacts. This review provides a comprehensive examination of these aspects. We begin by scrutinizing the production processes and formulation strategies of PBMAs, followed by an exploration of fundamental stabilization aspects, including homogenization, emulsification, thickening, and quantitative measurements of stabilization. Additionally, we discuss their nutrition facts and potential health benefits, as well as potential differences in the digestion of nutrients from PBMAs. Importantly, their challenges and future directions are discussed individually, highlighting the need for a fundamental understanding and effective food technologies to develop sustainable, nutritious, tasty, and affordable PBMAs. For example, several critical aspects involve maximizing the use of plant materials (e.g., proteins, fibers, and bioactive compounds) and using reliable and unified life cycle analyses to guide the development. This review offers valuable insights for researchers, food technologists, and consumers seeking to navigate and develop the landscape of PBMAs effectively.

Comparative effect of exogenous protease and phytobiotics on growth performance, nutrient digestibility, ileal histology and bone strength in broilers

ABSTRACT A total of 540 d-old Cobb 500 broiler chickens were randomly allocated into five groups: a control group receiving only the basal die (control), and experimental groups supplemented with exogenous protease (30,000 IU/kg) and crushed seeds of Bunium persicum, Coriandrum sativum, and Carum copticum (10 mg/kg each) for a period of 35 days. The results demonstrated that growth performance parameters, including feed intake, weight gain, and feed conversion ratio, were significantly improved (P < 0.05) in broilers supplemented with protease compared to those receiving the selected herbs. Additionally, the digestibility of crude protein and crude fat showed a significant increase (P < 0.05) in broilers that received protease compared to the Bunium persicum. Tibia bone weight significantly improved (P = 0.01) in birds supplemented with protease, Coriandrum sativum and Carum copticum. In addition, the robusticity index decreased (P < 0.05) in protease supplemented group. In terms of ileal histological features increased (P < 0.05) in broilers supplemented with protease compared to the control. In summary, the results indicate that protease supplementation yielded superior outcomes in terms of improving growth, ileal digestibility, bone quality, and villus dimensions in broilers compared to the herbal plant supplements used in this study.

Different Physiochemical Properties of Novel Fibre Sources in the Diet of Weaned Pigs Influence Animal Performance, Nutrient Digestibility, and Caecal Fermentation.

The effect of including micronised fibre sources (FS) differing in fermentability and hydration capacity (HC) on growth performance, faecal digestibility, and caecal fermentation was investigated in piglets. There were four dietary treatments: a control diet (CON) and three treatments differing in the HC and fermentability of FS added at 1.5% to prestarter (28-42 d) and starter (42-61 d) diets. These were: LHC (low-HC by-product-based insoluble fibre (IF) with a prebiotic fraction (PF) from chicory root); MHC (medium-HC by-product-based IF with a PF); and HHC (high-HC non-fermentable wood-based IF with no PF). There were eight replicates per treatment. Over the entire period, LHC and MHC piglets showed a 10% increase in daily growth and feed intake (p ≤ 0.019) and tended to have a reduced feed conversion ratio (p = 0.087) compared to HHC piglets. At 42 d, faecal protein digestibility increased by 5% in the LHC and MHC groups compared with the HHC group (p = 0.035) and did not differ from the CON group. Both LHC and MHC fibres were more fermented in vitro with caecal inocula from 61 d old piglets than HHC fibre (p ≤ 0.003). These results suggest that balanced soluble and insoluble fibre concentrates can improve piglet performance.

Performance, Feeding Behavior, and Nutrient Utilization of Different Goat Breeds Fed Creep Feed

Introduction: Feed is one of the main factors to improve animal production. The utilization of feed is depended on quality, quantity, type, breed, and rate of passage of feed. This study aimed to evaluate the performance, feeding behavior, and nutrient utilization of growing Etawah crossbred and Senduro goats fed different forms of starter concentrate of creep feed. Materials and methods: Twelve local growing goats were used in this study, consist of six Etawah crossbred and six Senduro goats with average body weight 20 ± 1.57 kg from both sex, fed different forms of creep feed for three month. This study was designed by factorial randomized completely block design 2x2. The first factor was type of creep feed form (mash and pellet), and the second factor was the type of goat breeds (Etawah crossbred and Senduro). The complete ration consisted of 70% creep feed containing black soldier fly (BSF) meal and BSF oil plus 30% elephant grass. The variables observed were feeding behavior nutrient consumption, digestibility, blood metabolites, and performance. Results: The results showed that there was no interaction between the creep feed forms and the goat breeds in all variables. The form of creep feed had a significant effect on prehension and mastication and the pellet form had higher prehension and mastication compare to mash from but it had no significant effect on nutrient consumption and digestibility. Performance and blood metabolites were same in all treatments, except for the feed efficiency of Senduro goats had higher than Etawah crossbred goats. Conclusion: In conclusion, giving creep feed containing BSF larvae meal and oil in starter concentrate as pellet forms resulted a lower prehension and higher mastication, but has higher prehension and lower mastication for mash type. The performance and blood metabolites were are not different in all treatment groups.

Source-dependent effects of early-life zinc supplementation in milk on growth performance and starter intake of pre-weaned dairy calves

This study aimed to evaluate the effects of milk supplementation with different zinc (Zn) sources on growth rate, starter intake, diarrhea incidence, and nutrient digestibility in dairy calves during the pre-weaning period. Forty newborn Holstein heifer calves were assigned to four treatments: control (no Zn supplementation; CON) or supplementation with 80 mg/day Zn from zinc sulfate (Zn-Sul), chelated zinc (Zn-Bon), or zinc methionine (Zn-Met). The Zn supplements were provided via milk from days 3 to 14 of age. Body weight (BW) and starter intake (SI) were monitored until weaning on day 70. Serum metabolite concentrations were determined in blood samples collected on days 15 and 70. Fecal consistency index (FCI) and frequency of medical treatments were measured during the first 21 days of life. Apparent total tract digestibility (ATTD) was determined in the 10th week of life. Although the effects of Zn supplementation on BW gain or body measurements were non-significant, a tendency for treatment × time interaction on BW was observed, with variations among the experimental groups becoming more pronounced on days 56 and 70, showing higher values in Zn-supplemented calves compared to CON. SI was improved by Zn supplementation, with the greatest response in the Zn-Bon group. Compared to control, ATTD of organic matter, neutral detergent fiber, and starch tended to increase with Zn supplementation. Blood metabolites and FCI did not differ among the experimental treatments. Although no significant difference was detected between Zn-Met and CON, the frequency of medical treatment was significantly lower in Zn-Bon and Zn-Sul compared to CON calves. In conclusion, zinc supplementation in milk, particularly with the organic chelated zinc source (Zn-Bon), showed promising effects on increasing starter intake and reducing medical treatments, along with trends toward enhanced growth and nutrient digestibility in pre-weaned calves.

Advances in Research on the Relationship between Diet, Gut Microbes, and Health

In recent years, as research on gut microbiota has deepened, the relationship between diet, gut microbiota, and health has garnered widespread attention. As the largest micro-ecosystem in the human body, gut microbiota not only participates in physiological processes such as food digestion and nutrient absorption but also exerts a profound impact on human health through its metabolic products and interactions with the host. This paper reviews the impact of diet on gut microbiota, and the relationship between gut microbiota and health, aiming to provide new strategies and ideas for promoting human health. Firstly, the article summarizes the effects of different dietary components and dietary patterns on the structure and function of gut microbiota. Then, it analyzes the role of gut microbiota in maintaining human health and preventing diseases and further explores the relationship between gut microbiota and intestinal diseases and metabolic syndrome. The analysis reveals that diet affects human health by influencing the structure and function of gut microbiota, while gut microbiota, as a complex ecosystem within the human body, plays an indispensable role in maintaining human health.

Isolation of Lactobacillus Species from Different Types of Milk and Evaluate their Antagonistic Activity Against Pathogens

Animal milk has been consumed by humans for a very long time. In the food industry, the probiotic Lactobacillus is regarded as a good substitute to lower the risk of food-borne illnesses. The bacteria Lactobacillus aids in the body’s nutrient absorption, digestion, and defense against pathogens. Determination of Lactobacillus from unfermented and reconstituted Milk. The initial and biochemical tests allowed for the identification of the organisms. The two pathogens, identified as Escherichia coli and Staphylococcus aureus were isolated in light of the findings. The purpose of these two pathogens, selection was antagonistic research. With the cross-stretched method, the antagonistic activity test was conducted. The outcome demonstrates that there is more inhibition displayed by the Lactobacillus grown in buffalo milk. In an antagonistic test, the probiotic organism inhibits the test pathogens.

Gastrointestinal tract morphology, nutrient digestibility, and digesta mean retention time in laying hens of two different breeds fed with fine or coarse oat hulls

The inclusion of fiber-rich ingredients in poultry diets is expected to increase due to societal-, ecologic-, and economic developments. Particle size of dietary fiber sources, such as oat hulls (OH), has been shown to play a key-role in nutrient digestibility and digestion process, but the response may depend on the genetic background of the bird. This study aimed to test the hypothesis that laying hens varying in genetic background respond differently to the particle size of OH regarding gastrointestinal tract development, apparent ileal (AID) and total tract digestibility (ATTD), and digesta mean retention time (MRT). A total of 224, 29-wk-old Dekalb White (DW) and Bovans Black (BB) laying hens were assigned to 1 of 2 dietary treatments (fine vs. coarse OH). The diets were formulated to contain 150 g/kg OH as the main dietary fiber source. Titanium dioxide (3 g/kg) and cobalt-EDTA (2 g/kg) were added as inert tracers. Bovans Black hens had greater relative weights of the gizzard (+3.9% of BW, P = 0.015), ceca (+14.3% of BW, P < 0.001), and colon (+9.1% of BW, P < 0.001) compared with DW hens. Moreover, AID of nitrogen (+3.5%; P < 0.001) was greater in BB vs. DW hens, whereas AID of starch was only greater in BB when fed the fine OH diet (breed × diet, P = 0.037). In contrast, ATTD of NSP (-11.2%, P = 0.035) was lower in BB vs. DW hens and digesta MRT was longer in proventriculus + gizzard (solids: +25 min, P < 0.001; liquids: +5 min, P < 0.001) and ileum (solids: +53 min, P = 0.001; liquids: +38 min, P < 0.001). Birds fed coarse OH only had a greater relative weight of the gizzard (+3.9%, P < 0.001) compared with those fed fine OH. In conclusion, our study indicates that gastrointestinal tract traits, nutrient digestibility and digesta transit behavior differed between breeds, regardless of the particle size of OH in the diet.

Use Of Ginger (Zingiber Officinale Roscoe) In The Diet Of Confined Sheep

The objective of this study was to evaluate the inclusion of ginger (0.0%, 0.2%, 0.4% and 0.6%) in the diet of sheep as a natural additive on the intake and digestibility of nutrients, in addition to ruminal parameters. Four mixed breed sheep with an initial body weight of 25 kg were used, distributed in a Latin square experimental design (4x4). The diets were balanced with 12.0% crude protein (isoprotein) and 69.5% total digestible nutrients (isoenergetic). The studied variables were subjected to analysis of variance and the observed differences were determined by regression analysis considering 5% significance. The mean values obtained for the intake values expressed in kg animal-1 day-1 for DM; OM; CP; EE, NDF; ADF; TCH and CNF were 0.64; 0.60; 0.058; 0.011; 0.29; 0.19; 0.51; and 0.22, respectively. The mean values of the nutrient digestibility coefficients were 51.59; 64.92; 55.97; 76.86; 39.73; 30.68; 52.54; and 69.50%, respectively, for DM, OM, CP, EE, NDF, ADF, TCH, and NFC. No interaction effect was observed for the pH of the ruminal fluid; however, the pH value differed in relation to time. The concentration of N-NH3 in the ruminal fluid differed. The inclusion of up to 0.6% ginger in the diet of confined sheep does not alter the values of intake and nutrient digestibility coefficient; however, the inclusion of 0.4% ginger allows a higher concentration of N-NH3 in the ruminal fluid in the time interval of 2h12min after feeding, requiring the inclusion of rapidly fermented carbohydrates in the diet

PSVI-30 Comparative analysis on partial replacement of soybean meal with various plant sources on growth performance, nutrient digestibility, and meat quality in finishing pigs

PSVI-30 Comparative analysis on partial replacement of soybean meal with various plant sources on growth performance, nutrient digestibility, and meat quality in finishing pigs

PSIX-16 Effects of Bacillus coagulans GBI-30, 6086 on nutrient digestibility, fecal characteristics and metabolites, immunity, and microbiota of healthy adult dogs subjected to an abrupt diet change

PSIX-16 Effects of <i>Bacillus coagulans</i> GBI-30, 6086 on nutrient digestibility, fecal characteristics and metabolites, immunity, and microbiota of healthy adult dogs subjected to an abrupt diet change

Effect of saccharin (sweetener) supplementation on growth performance, nutrient digestibility, fecal microbial, and fecal score in weaning piglets

Effect of saccharin (sweetener) supplementation on growth performance, nutrient digestibility, fecal microbial, and fecal score in weaning piglets

Effects of forage feeding to calves on performance, rumen fermentation and nutrient digestibility: A meta-analysis

The literature on whether or not to feed forage is marked by inconsistencies, largely due to various factors associated with forage inclusion in calf diets. To elucidate these factors, we conducted a 3-level meta-analysis to comprehensively investigate the overall effects of forage provision in young calves. We searched for studies published between 2000 and 2023 in Google Scholar, ScienceDirect, and X-Mol. Moderator analyses were performed to evaluate the effects of different forage sources, forage provision methods, starter forms, milk levels and forage levels on the heterogeneity of growth performance, rumen fermentation and nutrient digestibility outcomes in studies feeding forage to calves. Mixed-effect model was used to predict the relationship between forage level and performance. Funnel plot and Egger's test were used to determine publication bias. A total of 86 treatment comparisons from 36 articles were included in the final data set. The weighted mean difference (WMD) was used to evaluate the effect size, and the statistical heterogeneity of the effect size was estimated using Cochrane's Q test. The results showed that forage supplementation improved growth performance, structural growth, and development of rumen fermentation in calves. However, moderator analyses revealed that several factors, including forage source, feeding method, physical form of starter, milk feeding level and forage feeding level might contribute considerably to variability, resulting in significant heterogeneity in the effects of forage provision in calves. Larger effect sizes were found for oat hay (OH) supplementation rather than alfalfa hay (AH) or straw, feeding forage as a free-choice (FC) compared with a total mixed ration (TMR; defined as a mixture of calf starter and forage), especially when forage was fed as a FC resulting in higher total dry matter intake (TDMI) and body barrel. Forage supplementation was more effective in boosting calf growth in calves provided ground starter than in calves fed pelleted and textured starter. Greater effects were shown for AH supplementation than OH or straw in improving rumen fermentation parameters. Furthermore, compared with the preweaning period, the effect of providing forage on calves was more noticeable in the postweaning period. The results of the mixed-effects model analysis indicated that calves can be efficiently fed 12% of dry matter as forage during the preweaning period to support their growth and development. Meanwhile, 9% of dry matter might be the optimal level for feeding OH and straw to preweaning calves. More studies are essential to explore how different levels of AH dietary supplementation affects calves during the preweaning period, to improve the consistency and accuracy of the dose-response curve predictions. Overall, growth performance and rumen fermentation of dairy calves were affected by forage inclusion. Moreover, forage source, feeding method, physical form of starter, milk feeding level, and forage level are essential factors that result in different degrees of effect on the calf's performance and rumen fermentation.