Ⅰ. INTRODUCTION

Italian ryegrass (Lolium multiflorum Lam., IRG) is among the most widely cultivated winter forage crops due to its high yield, excellent nutritional profile, and adaptability to diverse climatic conditions. Particularly in temperate regions such as South Korea, Europe, and North America, IRG serves as a principal forage for ruminants, providing abundant crude protein and digestible fiber (Van Soest et al., 1991;Park, 2011).

Despite its agronomic advantages, IRG utilization is hindered by challenges related to storage, transportation, and feed conversion efficiency. Traditional preservation methods such as hay and haylage suffer from limitations, including bulkiness, vulnerability to spoilage, and inconsistent nutrient retention depending on storage conditions (Hoffman et al., 1993;Reddy et al., 2018). Consequently, pelletization has gained attention as a promising alternative for enhancing IRG usability, offering improvements in storage density, transportation efficiency, and feed stability (Moon et al., 2016).

Pelletized forages exhibit higher bulk density, better microbial stability, and reduced feed losses, making them suitable for large-scale livestock production (Rexen and Thomsen, 1976;Wilson and Harris, 1995). Moreover, pelleting can improve ruminant intake and digestion by delivering uniform nutrient composition and reducing selective feeding (Thompson et al., 2003;Yang, 2019). However, IRG pellet production requires careful optimization. High moisture in fresh IRG necessitates thorough drying and grinding, and excessive heat during pelletization can damage protein and fiber components (Lee et al., 2014). Studies suggest maintaining processing temperatures between 70°C and 90°C to balance pellet durability and nutrient retention (Yang, 2019).

The feeding efficiency of IRG pellets varies by animal species. In Hanwoo cattle (Bos taurus coreanae), IRG-based hay or silage has been shown to enhance growth and feed efficiency (Min et al., 2012;Yang, 2019), though limited studies have evaluated complete IRG pellet feeding. In contrast, Korean native black goats (Capra hircus) exhibit different preferences, especially in response to pellet size, texture, and density (Thompson et al., 2003). Larger pellet size can reduce intake in goats, emphasizing the need for species-specific formulation (Moon et al., 2016).

As South Korea moves toward increasing forage selfsufficiency, IRG stands out as a strategic feed resource. Nevertheless, a lack of research on high-IRG-content pellet processing and animal response limits its commercial application. Therefore, this study aims to: (1) evaluate the processing characteristics of IRG-based pellets; (2) assess feed intake and palatability in Hanwoo cattle and Korean native black goats; and (3) determine the feasibility of using IRG pellets as an alternative to conventional forage.

Ⅱ. MATERIALS AND METHODS

1. Experimental design and sample preparation

The experiment was conducted in 2020 at the National Institute of Animal Science, South Korea. Following pellet processing, the chemical composition of the samples was analyzed according to standard laboratory procedures (AOAC, 2012).

IRG was cultivated in Cheonan, South Korea, and harvested in 2020 at the optimal growth stage, specifically around the heading stage, to ensure maximum nutrient retention. The harvested IRG was sun-dried in the field before being processed into pellets. Previous studies (Mupangwa et al., 2000) have demonstrated that the harvest timing and drying method significantly influence the nutritional composition and physical properties of the final feed product; therefore, standardized processing conditions were maintained. To investigate the effect of IRG inclusion on pellet quality and feed performance, two types of IRG pellets were produced: (1) IRG ≥80% pellets containing up to 20% soybean meal to enhance crude protein content and (2) 100% IRG pellets composed exclusively of IRG. Pellet processing was performed using an industrial pellet mill employing a compression molding system, with processing temperatures controlled between 70°C and 90°C to minimize nutrient degradation (Moon et al., 2016). Pre-treatment processes, including moisture adjustment and particle size reduction, were applied to optimize IRG for pelletization. Large-scale production of pellets was carried out using a ring-die pellet mill for subsequent feeding trials.

2. Nutritional composition and physical properties evaluation

1) Nutritional composition analysis

To evaluate the nutritional composition of Italian ryegrass (IRG) pellets, several key parameters were analyzed using standard laboratory methods. The moisture content of the samples was determined using a thermogravimetric analyzer (TGA-701, LECO Corp., USA), following the guidelines established by AOAC (2012). The crude protein (CP) content was measured with a CN analyzer (Vario Max CN, Elementar Analysensysteme, Germany) where the total nitrogen content was converted to crude protein using a nitrogen-to-protein conversion factor of 6.25, as described by Van Soest et al. (1991). Crude fat content was analyzed through extraction using a Soxhlet extractor (XT15, ANKOM Technology, USA) method, based on the AOAC International method (2005). The ash content of the IRG pellets was determined by combusting the samples at 550°C for four hours, following AOAC (2012) standards. Additionally, the non-fibrous carbohydrate (NFC) content was calculated using a formula provided by Rexen and Thomsen (1976), which subtracts the sum of crude protein, neutral detergent fiber (NDF), acid detergent fiber (ADF), crude fat, and ash from 100. The fiber fractions, including NDF and ADF, were measured using a fiber analyzer (ANKOM 2000, ANKOM Technology, USA), adhering to the methodology described by Licitra et al. (1996). Furthermore, acid detergent insoluble crude protein (ADICP) was assessed following the standard protocol established by Licitra et al. (1996).

2) Physical properties evaluation

The physical characteristics of IRG pellets were evaluated through a soaking ability test, which assessed pellet disintegration potential in the rumen environment. A 10 g pellet sample was immersed in 100 mL of distilled water for 10 minutes, after which the extent of disintegration was recorded (Wilson and Harris, 1995).

3. Animal feeding trial

1) Hanwoo cattle experiment

To evaluate the feed intake and body weight changes associated with IRG pellet consumption, six Hanwoo cows (average body weight: 263 ± 1.44 kg) were used in the feeding trial. The experimental design consisted of a 1-week adaptation period followed by a 2-week feeding trial, during which IRG pellets were provided ad libitum (Yang, 2019).

The feeding protocol was established based on the Korean Feeding Standard for Hanwoo (2017), and feed intake was determined by measuring the daily intake of IRG pellets and the residual feed on the following day. At the end of the trial, body weight changes were recorded, and average daily gain (ADG) was calculated (Kwon et al., 2016).

2) Korean native black goat experiment

To assess the palatability and feed intake of IRG pellets in Korean native black goats, ten male goats (average body weight: 49.75 ± 3.00 kg) were used. The experimental design and feeding protocol were identical to those used for the Hanwoo cattle.

Each goat was provided with 400 g/day of concentrate feed along with either IRG ≥80% pellets or 100% IRG pellets under an ad libitum feeding regime. Feed intake and palatability were evaluated by measuring residual feed and monitoring feeding behavior patterns. Additional observations were made regarding the potential effect of pellet size on feed intake, as previous studies have indicated that goats tend to prefer smaller feed particles and may reduce intake if pellet size is too large (Thompson et al., 2003;Moon et al., 2016).

4. Statistical analysis

All collected data were analyzed using SAS (Statistical Analysis System, version 9.1, SAS Institute, Cary, NC, USA). Differences in feed intake and body weight changes between experimental groups were compared using an independent sample t-test, with statistical significance set at p<0.05 (SAS Institute, 2003).

Ⅲ. RESULTS AND DISCUSSION

1. Nutritional composition and physical properties of IRG pellets

The chemical composition of IRG pellets was analyzed to evaluate their suitability as a roughage source for ruminants. The crude protein (CP) content was 15.71% in IRG ≥80% pellets and 13.06% in 100% IRG pellets (Table 1). These values are consistent with previous reports on IRG hay, which showed CP contents ranging from 12% to 16% depending on harvest stage (Hunt and Alexander, 1961). The higher CP content in the IRG ≥80% pellets is attributed to the inclusion of up to 20% soybean meal, a high-quality protein supplement.

The fiber fraction analysis showed that 100% IRG pellets contained 49.76% neutral detergent fiber (NDF) and 29.69% acid detergent fiber (ADF), while IRG ≥80% pellets contained 45.36% NDF and 24.42% ADF (Table 1). These values indicate that the fiber content increased with higher IRG inclusion, which is consistent with previous findings on fiber-rich forage pellets (Rexen and Thomsen, 1976).

The soaking ability test revealed that all IRG pellets fully disintegrated within 10 minutes (Fig. 2), suggesting a high potential for rapid degradation in the rumen. This property is beneficial for efficient digestion and nutrient utilization in ruminants (Wilson and Harris, 1995).

2. Effects of IRG pellet feeding on Hanwoo cattle

Hanwoo cattle fed 100% IRG pellets exhibited significantly higher intake (7.9 kg/day/head) than those fed IRG ≥80% pellets (7.5 kg/day/head, p<0.05) (Table 2). However, average daily gain (ADG) did not differ between the groups (0.9 ± 0.4 kg/day/head), indicating that growth performance was maintained despite compositional differences.

The IRG ≥80% pellets contained up to 20% soybean meal to enhance crude protein (15.71% vs. 13.06% in 100% IRG). Nevertheless, the lower intake in this group suggests that soybean meal may have negatively affected pellet palatability possibly due to changes in texture or odor. This aligns with findings by Moon et al. (2016), who noted that processing conditions influence physical characteristics and intake in ruminants. Reddy et al. (2018) similarly reported that certain protein additives can reduce feed preference due to sensory drawbacks.

From a functional standpoint, the 100% IRG pellets with no soybean meal and lower crude protein still supported equivalent growth, demonstrating their adequacy as a sole nutrient source during the growing phase. More notably, this suggests a quantitative substitution effect, as properly processed IRG alone can replace not only the function but also the bulk of imported protein supplements in concentrate-based rations.

This finding is further supported by Onche et al. (2025), who observed improved feed efficiency in Hanwoo steers fed uniform, digestible pellet diets. Thus, when well-formulated, IRG pellets may offer a viable alternative to conventional high-protein feeds in Hanwoo feeding management systems.

3. Effects of IRG pellet feeding on Korean native black goats

In Korean native black goats, the average daily intake of 100% IRG pellets reached 266 g/head, which was substantially higher than the 54.6 g/head observed in the IRG ≥80% pellet group (Table 3). This result suggests a strong influence of both physical characteristics and formulation on feed acceptance in goats, consistent with prior findings (Thompson et al., 2003;Wilson and Harris, 1995).

Visual differences in pellet morphology were also observed (Fig. 1). Fig. 1B illustrates the size comparison between conventional grain pellets used for goats and the IRG pellets tested in this study. Goats are typically accustomed to small, grain-like particles, and the relatively large diameter of the IRG pellets may have negatively impacted feed intake. Moreover, when integrating this outcome with the intake differences found in Hanwoo cattle based on IRG content, it becomes evident that both physical structure and inclusion of soybean meal likely affected palatability and feed behavior.

Recent literature further supports this interpretation. Lopes et al. (2023) reported that reduced particle size significantly increases voluntary intake in goats, while Xue et al. (2022) emphasized the need to optimize physically effective fiber (peNDF) to support efficient digestion in small ruminants. Onche et al. (2025) demonstrated that pelleted diets with improved uniformity and digestibility enhance feed efficiency in cattle, underlining the importance of species-specific pellet design.

Taken together, these results suggest that reducing pellet diameter and reevaluating the use of additives such as soybean meal may improve feed preference in goats. While soybean meal is commonly added to increase crude protein content (IRG ≥80% = 15.71% vs. 13.06% in 100% IRG), it may negatively influence palatability. Reddy et al. (2018) showed that high-protein additives can reduce intake in goats due to undesirable changes in taste and odor. Therefore, in this study, the notably lower intake observed in the IRG ≥80% group may be attributed not only to physical factors such as pellet size but also to the sensory impact of soybean meal inclusion.

Ⅳ. CONCLUSIONS

This study showed that 100% Italian ryegrass (IRG) pellets, despite lower crude protein content and absence of soybean meal, supported similar growth in Hanwoo cattle compared to IRG ≥80% pellets, indicating their potential as a partial substitute for imported protein sources. Higher intake in the 100% IRG group also suggests improved palatability. In Korean native black goats, feed intake was influenced by pellet size and formulation. Reduced intake in the IRG ≥80% group highlights the importance of physical and sensory factors in feed acceptance, underscoring the need for species-specific pellet optimization. IRG pellets can contribute to forage selfsufficiency, but further research is needed to assess their longterm nutritional impacts.