Geese are herbivorous waterfowl, especially in wild flocks. However, in modern intensive production systems, high-energy and high-protein concentrate feed has become the main component of meat goose diets. Although concentrate feed has high nutritional value, it is expensive. Solely feeding concentrate may bring uncontrollable nutritional diseases to goslings, thereby limiting meat goose production (1).

Therefore, people are increasingly interested in exploring unconventional feeds that can replace meat goose concentrate, reduce reliance on traditional feeds, and enhance sustainability (2). Whole-plant ensiled corn stalks (WECS) are one such alternative feed source. Compared to ordinary corn and ensiled straw, WECS have more complete and balanced nutritional components and potential benefits for animal health and welfare.

The digestive structure of geese has innate advantages in digesting high-fiber foods, such as WECS. Geese have a relatively independent and developed caecum, similar to the rumen of ruminants, which allows insufficiently digested food to stay inside for sufficient fermentation (3, 4). The caecum of geese contains cellulose-digesting microorganisms lacking in other avian digestive tracts, which convert cellulose into short-chain fatty acids (SCFAs) and provide energy to geese (5). In addition, the digestive tract of geese has strong motility and rotational ability, and the gizzard accounts for about 8% of their body weight (6). This helps to fully grind plant cell walls, promote the decomposition and utilization of cellulose (7).

Therefore, adding high-yield and low-cost WECS as an additional dietary supplement may reduce production costs and improve the intestinal health of geese. Although recent studies on using ensiled corn in meat goose production (8–10) have yielded encouraging results, the use of traditional ensiled corn stalks is mainly suitable for ruminants such as cows, beef cattle, etc., and their application in monogastric animals such as meat geese needs further research and confirmation.

Therefore, we conducted a study to explore the effects of adding different levels of WECS on meat goose growth performance and caecal microorganisms. The results of this study will help us understand the potential benefits and limitations of using WECS as meat goose feed and provide reference for their application in meat goose production.

The experimental procedures were conducted in compliance with the guidelines established by the Chinese Animal Care and Protocol Committee and approved by the Animal Care and Use Committee of the Shanghai Academy of Agricultural Sciences.

Whole-plant ensiled corn stover (WECS) is produced by chopping and ensiling the entire corn plant, including the stover, with the addition of a fermentation inoculant in a sealed container to allow for anaerobic fermentation (16). This process creates a low pH environment that promotes the growth of beneficial bacteria while inhibiting the proliferation of spoilage organisms (17). Geese fed on WECS not only directly absorb and utilize existing organic acids, but also promote the colonization of beneficial bacteria in their gastrointestinal tract. Moreover, WECS is rich in crude fiber, which can be partially digested and utilized, thereby increasing feed conversion rate and improving intestinal health. During the season of low availability of fresh green forage, WECS can provide animals with a stable source of nutrients and microbial biomass, and its high quality as a silage feed has been widely applied in animal production. Zhang et al. (18) showed that feeding WECS to fattening bulls increased their average daily weight gain, reduced production costs, and improved rumen degradable protein and fermentation efficiency. Wu et al. (19) found that compared to whole-plant sorghum silage, feeding WECS significantly improved lamb growth performance and carcass traits. He et al. (20) found that compared to other crop straws, WECS could increase the activity of proteases in the gastrointestinal tract of geese, indicating that WECS can improve protein digestion in geese. The results of this experiment showed that feeding WECS significantly increased the average daily feed intake of Holdobagy, and adding 15% WECS increased the F/G of geese, indicating that WECS has good palatability for geese, and its acid aroma can enhance their appetite. Although the digestibility and utilization of WECS by geese is not high, resulting in an increase in F/G, feeding WECS does not affect the FBW and ADG of geese, which is consistent with the results of (21). From an economic point of view, although adding WECS may increase feed consumption in the goose farm, it will not have a negative impact on the growth of meat geese, and the price of WECS is less than half that of ordinary corn. Therefore, feeding WECS can improve the economic benefits of the farm, and the amount of WECS added should not be too small.

Fe is a major component of hemoglobin and myoglobin in the body, as well as an important component of various enzymes involved in physiological processes such as oxygen transport, immunity, and metabolism (22). Zn is an important cofactor for various enzymes and is involved in various metabolic and physiological processes such as protein synthesis, DNA synthesis, and maintenance of the immune system (23). Our research results show that feeding WECS affects the levels of Fe and Zn in goose serum, with the level of Fe in goose serum positively correlated with the addition level of WECS, and the level of Zn in goose serum negatively correlated with the addition level of WECS. This may be due to the stimulation of high levels of fiber and lignin in WECS, which continuously stimulate the proventriculus to secrete gastric acid, which aids in the digestion of iron, while possibly inhibiting the absorption of Zn, leading to an increase in Fe levels and a decrease in Zn levels in goose serum (24). In addition, the cellulose and anti-nutritional factor phytic acid in WECS may form complexes with zinc, reducing its bioavailability. Lactate dehydrogenase (LDH) is an enzyme that catalyzes reactions in animals and is widely present in the cytoplasm. LDH can catalyze the oxidative decomposition of lactate to provide energy for the body (25). The results of this experiment show that after feeding WECS, the level of LDH in goose serum significantly decreased and was negatively correlated with the addition level of WECS. The reason for the decrease in LDH may be due to the rapid synthesis and consumption of lactate. There are few nutrients in WECS feed that can be directly digested and absorbed by geese, and structural polysaccharides such as cellulose and hemicellulose need to be fermented and metabolized by microorganisms to produce organic acids such as lactate. The lactate is then directly provided to intestinal microorganisms and animal cells for oxidative decomposition to produce pyruvate and ATP, and the resulting pyruvate continues to participate in the tricarboxylic acid cycle to provide energy for the body, compensating for the low nutrient concentration in WECS feed to maintain normal goose life activities (26). In addition, the decrease in Zn levels in goose serum after feeding WECS may also be one of the reasons for the decrease in LDH levels. Zn is an important component of LDH, maintaining its stability and catalytic activity, and the decrease in serum Zn levels may also lead to a decrease in LDH levels (27). The decrease in LDH levels indicates that geese have a considerable digestive ability for WECS, but it should be noted that in diets with high proportions of WECS, additional Zn should be added to meet the needs of geese.

Principal Coordinates Analysis (PCoA) results showed two-dimensional projected distances indicating differences in bacterial community between samples with different WECS ratios. This suggests that varying WECS addition ratios could have an impact on the microbial composition of the goose cecum. Alpha diversity analysis indicated that the cecal microorganisms of geese in the 30WECS group had higher observed species, Shannon, and Pielou’s evenness indexes, suggesting that increasing the proportion of WECS could enhance the richness, uniformity, and diversity of goose cecal microorganisms. These findings are consistent with the results of Chao et al. (28).

Similar to previous studies, this experiment found that the phyla Bacteroidetes, Firmicutes, and Proteobacteria were the dominant bacterial phyla in the cecum of geese. Although adding WECS did not change the dominant bacterial phyla, it did affect their relative abundance (29, 30). Bacteroidetes is a gram-positive bacterial phylum associated with weight gain and feed intake (31, 32). The results of this experiment showed that the abundance of Bacteroidetes increased and then decreased with the increasing proportion of WECS addition. This may be due to the nutritional concentration of the feed and the digestive characteristics of the goose. Adding WECS can reduce the nutritional concentration of the feed, forcing geese to increase their feed intake to maintain their energy levels. At low addition proportions, the feed intake of geese increases, causing the food renewal rate in their intestines to accelerate. However, the cecum is not sufficiently adapted to the cellulose in WECS, which reduces the efficiency of digestion and absorption of feed nutrients and slows down weight gain. An increase in feed intake can increase the abundance of Bacteroidetes (33). However, as the proportion of WECS increases, more organic acids enter the goose’s intestines, which can be directly digested and utilized. The renewal rate of food in the intestine slows down, and the cecum becomes more adapted to the cellulose in WECS (34). This leads to an increase in the digestion and absorption rate of cellulose and feed, a decrease in feed intake, and a decrease in the abundance of Bacteroidetes (35). Additionally, the study found a positive correlation between the relative abundance of Cyanobacteria and the proportion of WECS addition, but the difference was not significant. The increase in abundance of Cyanobacteria may be due to the residual cyanobacteria on WECS entering the cecum of the digestive tract (7).

Alistipes is a genus of bacteria belonging to the family Bacteroidetes, which is widely found in the cecum of geese (10, 36). Our experimental results indicate that the abundance of Alistipes is negatively correlated with the proportion of WECS in the feed, suggesting that this bacterium avoids a diet rich in plant-based food and grows well in a low-fiber diet (37). Kong et al. (38) found that the abundance of Alistipes in the cecum of mice fed a high-fat, high-sugar diet increased significantly, which is consistent with our results. Studies suggest that Alistipes may play an important role in the breakdown of complex carbohydrates and the production of SCFAs, which can be used as a source of energy for the host. The abundance of Alistipes may be related to the concentration of starch in the cecum (39). Unlike geese fed concentrated feed, the starch concentration in the cecum contents of geese fed WECS is lower, resulting in a decrease in the abundance of Alistipes. Rikenella is a gram-negative rod-shaped bacterium and a member of the Rikenellaceae family, found in the cecum and feces of birds. Our research results indicate that the level of Rikenella in goose cecum was significantly reduced after feeding with WECS, consistent with the findings of (18). The decrease in Rikenella abundance may be attributed to its narrow metabolic capability. The main carbon source for Rikenella growth is glucose, and it can hardly hydrolyze the fiber polysaccharides in WECS, which may be the reason for its reduced abundance in the cecum (40). Parabacteroides is a genus of bacteria belonging to the family Bacteroidaceae, which is a common component of the human and animal gut microbiota. Currently, there is limited research on the role of Parabacteroides in the goose gut, but it has been shown to be one of the main species involved in the digestion of dietary fiber in the human gut, producing SCFAs that maintain gut health (41, 42). Our experimental results show that adding 30% WECS to the feed significantly increases the abundance of Parabacteroides in the goose cecum. Therefore, the abundance of Parabacteroides is positively correlated with the dietary fiber level in the feed. Butyricimonas is a Gram-negative anaerobic bacterium belonging to the family Lachnospiraceae, which ferments dietary fiber to produce butyric acid, providing energy to intestinal wall cells and maintaining a healthy gut microbiota, preventing enteritis (43). Our experimental results indicate that adding 15% ensiled corn significantly increases the abundance of Butyricimonas in the goose cecum. However, when the addition amount reaches 30%, the abundance of Butyricimonas decreases. This may be related to the pH of the ensiled corn feed, as high addition amounts can lower the pH of the feed and have an adverse effect on the cell wall of Butyricimonas (44).

In summary, adding WECS to the diet may increase feed consumption in geese, but it does not have a negative impact on their growth and can increase economic benefits. However, it is important to pay attention to the amount of WECS added and supplement the diet with Zn to meet the geese’s normal needs. The proportion of WECS in the diet does not appear to affect the major bacterial phyla in the goose cecum, but it does impact the overall microbial composition and abundance of certain bacterial phyla and genera. Increasing the proportion of WECS in the feed can enhance the richness, evenness, and diversity of the cecal microbiota. As the amount of WECS added to the diet increases, the abundance of Alistipes decreases. On the other hand, the abundance of Parabacteroides increases with an increasing proportion of WECS, while the abundance of Butyricimonas increases when 15% WECS is added and decreases when 30% WECS is added to ensiled corn.

All animal protocols were approved by the Shanghai Science and Technology Committee (STCSM) with a license number of SYXK (HU): 2015–0007, and carried out in accordance with approved guidelines and regulations. Every effort was made to minimise the suffering of the geese in the current study.

The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: https://www.ncbi.nlm.nih.gov/bioproject; PRJNA961934.

The animal study was reviewed and approved by the Animal Care and Use Committee of the Shanghai Academy of Agricultural Sciences (SAASPZ0522046), Shanghai Academy of Agricultural Sciences.

XW completed the experimental manuscript’s initial draft writing and inspection. HW and DH carried out the experimental design and paper editing. YY, GL, CW, and YL performed the data software analysis and sample collection. SG participated the on-site breeding of geese. All authors mentioned above have reviewed and approved the final manuscript.

This study was financially supported by the Climbing plan of Shanghai Academy of Agricultural Sciences [PG23171], the Earmarked Fund for China Agriculture Research System [CARS-42-35] and the SAAS Program for Excellent Research Team (SPERT), and the Special Project of Modern Agriculture [ZY221702].

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.