The global expansion of ethanol production, driven by the search for renewable energy sources and the depletion of fossil fuel reserves, has increased the availability of corn-based coproducts such as dried distillers’ grains with solubles (DDGS) for use in animal feed (Kumar and Singh, 2019). This scenario represents not only a response to energy demand but also an opportunity to promote a circular economy and sustainability, by transforming residues from biofuel production into valuable inputs for the feed industry. In Brazil, corn ethanol production is rapidly growing, and the poultry industry is particularly interested in these coproducts as alternative ingredients that can reduce feed costs and improve the sustainability of intensive production systems.

However, conventional DDGS presents limitations in poultry nutrition due to its high fiber content and variable nutrient digestibility, which restrict its inclusion levels in broiler diets (Abudabos et al., 2017a,b; Shurson, 2018; Hristakieva et al., 2023). Negative effects on performance have been reported at higher dietary concentrations (above 9%), particularly during the starter phase when the digestive tract is still developing (Lumpkins et al., 2004; Abdel-Raheem et al., 2011; Loar et al., 2012).

Emerging technologies, such as fiber separation technology (FST™; ICM Inc., Colwich, KS, USA), remove fiber before fermentation, improving ethanol yield and creating a coproduct known as high-protein DDG (HP-DDG). Compared with conventional DDGS, HP-DDG presents a more concentrated nutritional profile, characterized by higher crude protein (CP; >38%), metabolizable energy (3060 kcal/kg), amino acids, and minerals (0.27% available phosphorus, 0.51% potassium, 0.07% sodium), and reduced fiber content (6.87%) (Applegate et al., 2009; Shurson, 2018, 2, 2023; Dias et al., 2023; Calderano et al., 2024; VerBeek et al., 2024). These nutritional improvements suggest a potential for partial replacement of soybean meal (Fries-Craft and Bobeck, 2019), one of the costliest ingredients in poultry diets. Nonetheless, the nutrient composition of HP-DDG may vary depending on corn source and processing method, and its use in poultry diets depends on its actual digestible nutrient and energy content (Silva et al., 2022). In contrast to the United States, where the nutritional value of corn DDGS and HP-DDG has been more extensively characterized, Brazilian nutritionists still have limited familiarity with these coproducts. As a result, feeding recommendations in Brazil often rely on data generated in U.S. studies, which may not fully represent the characteristics of locally produced ingredients (Palowski et al., 2021).

This lack of knowledge represents a research gap that limits nutritionists’ ability to fully incorporate HP-DDG into practical diet formulations. Generating scientific evidence on its effects is especially relevant in Brazil, where the rapid expansion of corn ethanol plants is expected to increase the availability of HP-DDG. In addition, evaluating this coproduct contributes to more sustainable poultry production, as it promotes the valorization of biofuel coproducts and reduces dependence on soybean meal.

We hypothesized that HP-DDG could be included in broiler diets up to a certain practical level without impairing growth performance or carcass yield when compared with a corn-soybean meal control diet. Therefore, the objective of this study was to evaluate the effects of increasing dietary HP-DDG levels by comparing each level with a 0% inclusion control, to determine the maximum inclusion that maintains broiler performance from 1 to 43 days of age.

Birds fed 11% HP-DDG in the starter diet had a 3% lower BWG (P = 0.011) and a 2.8% lower BW (P = 0.011) compared to those in the control treatment (Table 3). However, no effects were observed when analyzing the performance from 1 to 33 days and from 1 to 43 days (P>0.05). Additionally, carcass and cut yields at 43 days were not affected by treatments (P>0.05; Table 4).

Table 3

	Inclusions of HP-DDG1						SEM	P-value
	1 to 21 days
	0%	3%	5%	7%	9%	11%
FI (g/bird)	1364	1383	1359	1372	1359	1371	0.006	0.877
BWG (g/bird)	1083	1093	1073	1060	1063	1050*	0.004	0.011
BW (g/bird)	1129	1139	1119	1107	1109	1097*	0.004	0.011
FCR (g/g)	1.260	1.265	1.267	1.294	1.279	1.306	0.005	0.085
	1 to 33 days
	0%	3-5%	5-7%	7-9%	9-11%	11-13%
FI (g/bird)	3338	3360	3369	3366	3351	3359	0.010	0.954
BWG (g/bird)	2368	2375	2393	2342	2365	2341	0.007	0.166
BW (g/bird)	2414	2422	2457	2388	2412	2387	0.007	0.195
FCR (g/g)	1.410	1.415	1.409	1.438	1.418	1.436	0.004	0.224
	1 to 43 days
	0%	3-5-7%	5-7-9%	7-9-11%	9-11-13%	11-13-15%
FI (g/bird)	5525	5501	5521	5532	5517	5543	0.016	0.985
BWG (g/bird)	3527	3467	3486	3505	3504	3489	0.007	0.254
BW(g/bird)	3574	3513	3549	3552	3551	3536	0.008	0.332
FCR (g/g)	1.567	1.587	1.585	1.578	1.575	1.588	0.004	0.669

SEM - standard error of the mean.

Table 4

	0%	3-5-7%	5-7-9%	7-9-11%	9-11-13%	11-13-15%	SEM	P-value
CY (%)	79.7	79.7	79.2	80.0	80.9	79.4	0.261	0.531
BY (%)	34.7	34.7	34.8	33.7	34.7	34.5	0.209	0.681
WY (%)	9.41	9.61	9.56	9.47	9.48	9.55	0.046	0.852
DY (%)	14.7	14.8	14.7	14.7	14.7	14.9	0.094	0.965
TY (%)	12.7	12.6	12.7	12.9	12.7	12.7	0.068	0.930

SEM - standard error of the mean.

The starter phase is crucial for skeletal and gastrointestinal development, which directly impacts broiler growth. In this study, birds fed 11% HP-DDG had a 2.8% lower BW and a 3.0% lower BWG compared with the control group during the starter phase, indicating that high levels of inclusion in early life may compromise initial growth. This effect is likely due to the combination of higher dietary fiber from HP-DDG and the immature gastrointestinal tract in young chicks, which can transiently reduce nutrient utilization efficiency. Similar findings were reported by Fries-Craft and Bobeck (2019), who observed impaired performance with 15% HP-DDG during the starter phase. However, they also reported no differences with 10% inclusion, aligning with our findings that performance was maintained up to 9% inclusion. On the other hand, Jung and Batal (2010) reported no differences in broilers’ performance when fed HP-DDG up to 16% during the starter phase.

Interestingly, VerBeek et al. (2024) reported that turkey poults fed HP-DDG showed a temporary reduction in FI from 1 to 14 days, which was attributed to delayed pancreatic enzyme secretion during early development. However, this reduction did not affect BW and FI normalized in the subsequent phase (15 to 32 days). While caution is warranted when extrapolating across species, it is reasonable to suggest that a similar transient adaptation could have occurred in our broilers before 14 days of age. By 21 days, FI may have already normalized, which would explain why cumulative FI was not affected in our study. Therefore, the BWG reduction at 21 days can be interpreted as a short-term effect of digestive adaptation rather than a persistent impairment. Nonetheless, because BWG in broilers is particularly sensitive during the starter phase due to the accelerated development of the gastrointestinal tract and other organs (Shani and Irani, 2024), even a brief reduction in nutrient utilization efficiency at this stage could manifest as the modest reductions in BW and BWG observed at 21 days, without causing long-term impairment in overall performance.

Fries-Craft and Bobeck (2019) associated poor performance in the grower and finisher phases and throughout the overall period with the reduction in performance observed in the starter phase. However, our results showed that birds with lower BW and BWG in the starter phase did not experience performance impairment in the subsequent rearing phases. This suggests that birds were able to compensate for the initial growth reduction once the digestive tract matured and nutrient absorption normalized.

The inclusion of HP-DDG up to 16% decreased the performance of broiler chickens from 0 to 33 days old when compared with the control group without without HP-DDG inclusion (Jung and Batal, 2010). Moreover, it was reported that 15% and 20% HP-DDG negatively affected performance parameters in the grower phase (Fries-Craft and Bobeck, 2019). These findings diverge from the results of the present study and those of VerBeek et al. (2024) in turkey poults, where increasing levels of HP-DDG or its inclusion at 15% in the rearing phases had no negative effect when the period from 1 to 33 days of age was evaluated.

Overall, HP-DDG inclusion was not reported to affect broilers’ performance from 0 to 42 days (Applegate et al., 2009), except for the studies by Fries-Craft and Bobeck (2019) and Mustafa et al. (2017). In the former, the authors stated that poor performance was linked to HP-DDG inclusion and its amino acid content. They observed that increasing levels of HP-DDG decreased Lys and Met + Cys levels in the diets, leading to a deficiency, which can occur due to the lower Lys content in HP-DDG compared with soybean meal (Dias et al., 2023). Therefore, there is a need for supplemental amino acids, especially Lys, when replacing soybean meal with HP-DDG. In the present study, diets were formulated to account for this requirement for supplemental amino acids, as we increased Lys supplementation as HP-DDG levels increased in the diets, which could explain why we did not find any negative effects on overall performance. In other words, the adequate adjustment of amino acid balance likely prevented the reductions observed in other studies. However, Mustafa et al. (2017) reported better BW, BWG, and FCR in broilers fed 7.5% HP-DDG at 42 days of age, which was attributed to improvements in villus height and crypt depth that increased the absorptive surface area.

Energy, AA, and fiber content differences can be observed among corn coproducts. Regarding AA and CP contents, soybean meal and HP-DDG used in the present study had similar CP content. On the other hand, both feedstuffs differed considerably in fiber content. The HP-DDG contained 6.06% CF, 24.14% NDF, and 16.88% ADF, whereas the soybean meal contained 4.82% CF, 11.6% NDF, and 7.07% ADF (Dias et al., 2023; Calderano et al., 2024). It is a characteristic of corn coproduct feedstuffs, in which the high dietary fiber content is mainly composed of non-starch polysaccharides (Knudsen, 2014; Sanchez et al., 2021). In poultry nutrition, dietary fiber is often considered antinutritive because of its limited contribution to energy supply and its disruption of digestive processes by increasing digesta viscosity in the intestinal tract and reducing nutrient availability and the overall nutritive value of the diets (Mateos et al., 2012; Sanchez et al., 2021). Therefore, it could impair broilers’ growth by decreasing nutrient utilization, especially in the starter phase when the gastrointestinal tract is developing.

However, some authors suggest that structural materials, like fiber, stimulate the development and physiology of the gastrointestinal tract, especially the gizzard, and stimulate the secretion of HCl, bile acids, and enzymes (Mateos et al., 2012; Njeri et al., 2023). Njeri et al. (2023) found that broilers fed a diet with high fiber content, represented by the addition of 10% DDGS, had higher gizzard weight and better FCR, which the authors indicated was due to the fiber source effectively promoting gizzard development. Although increasing fiber content through HP-DDG could have impaired the starter performance in the present study, its gradual addition may have conditioned the digestive tract of birds for the next rearing phases and maintained growth performance. Thus, the initial challenge imposed by fiber may have ultimately contributed to a more efficient digestive capacity later on.

The results regarding carcass and cut yields were consistent with the performance results, as no differences were observed. Mustafa et al. (2017) observed that broilers fed 7.5% HP-DDG had higher breast, thigh, and drumstick weights at 42 days compared with the group fed no HP-DDG, which was attributed to the physiological and morphological improvements previously discussed.

The gradual inclusion of HP-DDG in broiler diets up to 15% does not impair overall growth performance or carcass yield. However, inclusion levels should not exceed 9% during the starter phase to avoid initial growth loss.