INTRODUCTION
Due to its nutritional value, corn (Zea mays L.) is one of the main ingredients used in the diets for poultry worldwide. Brazil is one of the largest corn producer and exporter countries (USDA, 2021), and, according to ABIMILHO (2023), about 50% of the corn produced in Brazil in the 2019/2020 harvest was used for animal consumption, reaching more than 54% in the 2022/2023 harvest. The grain is globally traded as a commodity because it is a homogeneous product from which is expected small variability in its characteristics (PRATES, 2007) and its price is regulated by the supply and demand principle. However, high prices scenarios have an impact on the cost of feed formulations, affecting the whole animal production chain, and, consequently, meat prices.
The natural composition of corn is susceptible to mycotoxin contamination. The contamination by mycotoxins depends on several factors such as seed genetics, growing location, soil fertility, climate conditions, and pre- and post harvest handling (FAO, 2024). The main mycotoxinproducing fungi found in corn are Aspergillus and Fusarium, which can produce mycotoxins from the groups of aflatoxins, fumonisins, and trichothecenes, respectively (MALLMANN & MALLMANN, 2020). Therefore, it is important to provide current information on how some of these factors can impact the characteristics of corn and; consequently, its utilization. Furthermore, it is important to consider the use of antimycotoxin additive (AMA) when identifying mycotoxin contamination, seeking tested products with guaranteed efficacy for the groups of mycotoxins and animal species being worked with.
In the 2020/2021 harvest, 98 new corn cultivars were introduced in the Brazilian market (EMBRAPA, 2021); however, technical improvement of corn has primarily focused on developing high-yield hybrids with resistance to lodging and pathogens. There are no nutritionally certified hybrids available in the market, and there is limited information regarding resistance to fungal attacks and potential mycotoxins contamination.
In this context and considering that corn is the primary cereal in the global animal nutrition chain, the nutritional composition and the quality of corn hybrids should therefore be considered in the genetic selection and improvement processes. Therefore, this study assessed the productivity, nutritional composition, and presence of mycotoxins in different corn hybrids cultivated in the same harvest in Brazil, focusing on poultry nutrition. Information on nutrients composition and mycotoxins contamination from each corn hybrid was also considered to formulate starter diets for broilers and to evaluate the impact of these variables on feed formulation cost.
MATERIALS AND METHODS
Field experiment
The experiment was conducted at the Agricultural Research Center (24°37’18”S; 53°18’ 20”W; 580 m altitude) of the Cooperativa Agroindustrial Consolata (COPACOL), in Cafelândia city, western region of the Paraná State, Brazil. The soil was classified as dystroferric red latosol. In February 2020, 50 commercial and pre-commercial corn hybrids were cultivated in a consolidated no-tillage system under the same agro-climatic conditions and soil type. The identification of corn hybrids was done numerically (from 1 to 50) and the commercial names have been withheld to ensure confidentiality. The experiment was design in a randomized blocks design with three replicates of each corn hybrid. Experimental plots consisted of four corn rows with a spacing of 68 cm, having 2.72 m in width by 10 m in length. Crop phytosanitary management was conducted according to the technical recommendations on pest and weed control. The soil fertilization was conducted according to chemical analyses, employing a base fertilization of 300 kg/ha of 10-15-15 (NPK).
Harvesting was performed in July using a Wintersteiger combine® experimental plot harvesterclassic model, where the two central lines of each plot were harvested, totaling 13.6 m2 of useful plot. The mass of grains and gravimetric moisture content were automatically determined by the Easy Harvest weighing system (Grain Gage®) coupled to the harvesting system. The crop yield of the experimental plots was calculated in kg/ha and adjusted for 13% moisture. Grains that were damaged were classified according to MAPA recommendations (BRASIL, 2011) and the percentage of damaged grains was obtained by the equation: [weight of damaged grains (g)/weight of the sample (g)]* 100.
Quantification of mycotoxins by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS)
After harvesting, samples were dried in a forced-air oven at 55 °C for 12 h and prepared for mycotoxins and nutrients analyses. Mycotoxins quantification was conducted in the Laboratory of Mycotoxicological Analyses at Federal University of Santa Maria, Brazil. Analytical standards for aflatoxins (AFLA) AFB1 , AFB2 , AFG1 , AFG2 , fumonisins (FUM) B1 (FB1 ) and B2 (FB2 ), deoxynivalenol (DON), and zearalenone (ZEA) were purchased from Sigma Aldrich (St Louis, MO, USA). Methanol, acetonitrile, formic acid, and ammonium acetate (HPLC grade) were purchased from JT Baker (Center Valley, PA, USA). Ultrapure water was obtained from a Milli-Q Water Purification System. The limits of detection (LOD) and quantification (LOQ) (in μg/kg) for the assessed mycotoxins were, respectively: 0.4 and 1 for AFB1 ; 0.6 and 1 for AFB2 , AFG1 and AFG2 ; 10 and 125 for FB1 ; 20 and 125 for FB2 ; 3 and 20 for ZEA; and 50 and 200 for DON.
Samples of 1 kg were milled at 1 mm using an ultra-centrifugal mill (RETSCH®, model ZM 200), homogenized and then analyzed for mycotoxins presence. Analyses of AFLA, FUM, DON and ZEA were performed according to MALLMANN et al. (2020). For AFLA, a 5 g sample was mixed with 20 mL acetonitrile–water solution (84:16, v/v) and shaken on a shaking table for 60 min. The resulted extract was spun (Eppendorf 5804R) at 2,500 rpm, 20 °C, for 5 min, and then 60 μL was diluted with 840 μL methanol–water (1:1, v/v) solution. For FUM, 3 g of sample was mixed with 15 mL acetonitrile–water solution (1:1, v/v) and vortexed for 20 min in an orbital shaker. The extract was spun at 2,500 rpm, 20 °C, for 5 min, and then 20 μL was diluted in 980 μL acetonitrile–water–formic acid solution (50:40:10, v/v/v). For DON and ZEA, a 3 g sample was mixed with 24 mL methanol–water (70:30, v/v) solution and vortexed for 20 min using an orbital shaker. The resulted extract was spun at 2,500 rpm, 20 °C, for 5 min, and then 40 μL was diluted in 960 μL methanol– water–ammonium acetate solution (90:9:1, v/v/v). For the four mycotoxins, 20 μL of the diluted solution was injected into a 1200 Series Infinity HPLC instrument (Agilent, Palo Alto, CA, USA) coupled to a 5500 QTRAP mass spectrometer (Applied Biosystems, Foster City, CA, USA) equipped with an electrospray ionization source in positive mode. Chromatographic separation for AFLA and FUM was performed at 30 °C using an Eclipse XDB-C8 column (4.6 × 250 mm, 5 μm particle diameter) (Agilent) and for DON an ZEA at 40 C with a Zorbax SB-C18 column (4.6 × 150 mm, 5 μm) (Agilent).
NIRS nutritional predictions
For predictions by near infrared spectroscopy (NIRS), samples were milled through a 0.5 mm sieve in an ultra-centrifugal mill (RETSCH®, model ZM 200). Samples were then placed in plastic bags and left for 15 min to reach room temperature (between 18 °C and 22 °C) and humidity (between 40% and 60%). Subsequently, manual homogenization of each sample was performed for two min in a plastic bag using circular movements. Nutritional predictions were performed by reading the spectra of the samples in a Bruker® instrument, model Tango-R, with a wavelength range of 3,952 - 11,536 cm-1, using the calibration curves from the AMINONRG® and AMINONir® programs (Evonik Nutrition & Care GmbH, Hanau, Germany). The following variables were predicted: dry matter (DM) (%), crude protein (CP) (%), ether extract (EE) (%), ash (%), total phosphorus (TP) (%), phytic phosphorus (PP) (%), total and digestible (dig.) amino acids (AA, %) for poultry, and apparent metabolizable energy (AMEn ) (kcal/kg) for poultry. For study and comparison purposes, all values were adjusted to 87% DM basis.
Feed formulation and AMA inclusion in the diet
Average nutrient composition and mycotoxins contamination were calculated for each corn hybrid and used to calculate the cost of feed formulation of starter diets for broilers (8 to 21 days of age) using each hybrid as the corn source in the formula. The starter diet was used in this investigation due to the high susceptibility to mycotoxins that broilers present at this phase (MALLMANN & MALLMANN, 2020). Feeds were formulated using the PPFR spreadsheet (UNESP, SP, Brazil) and following recommendations of ROSTAGNO et al. (2017) for standard-high performance male broilers. Costs were obtained from market prices in the region of the study in November 2020 (Table 1). The inclusion of the AMA was calculated proportionally to mycotoxins concentration levels of each corn hybrid and based on the Mycotoxins Risk algorithm (MALLMANN & MALLMANN, 2020). The inclusion of AMA was adjusted as follows: 2.5 kg of AMA/t of feed for every 28 µg/kg of AFLA + 2.5 kg of AMA/t of feed for every 10,000 µg/kg of FUM.
Statistical analyses
Data were analyzed using the Statgraphics® software (Statgraphics Centurion 15.2.11, Manugistics Inc., Rockville, MD, USA). Different variables were submitted to analysis of variance and the Scott-Knott test was used to group hybrids with similar characteristics at 5% significance. To summarize the information in a smaller set of results that can be easily observed, Pearson correlation analysis was conducted among the main variables.
RESULTS AND DISCUSSION
Corn is one of the most produced cereals in the world, with a global production exceeding 1.1 billion tons in the 2020/2021 harvest season (USDA, 2021). Genetic improvement in the major cornproducing countries has led to a significant increase in productivity per cultivated area. Results of field traits and mycotoxins contamination of the corn hybrids are presented in table 2. For crop yield, the 50 corn hybrids were divided into 4 distinct groups (P < 0.05) with an average productivity of 7,407 kg/ha. The difference between the most and the least productive hybrid was 2,935 kg/ha. The average crop yield in the current study is 34% higher than the Brazilian average in the 2019/2020 harvest, which was 5,510 kg/ha, and 28% superior than the global average of 5,780 kg/ha (USDA, 2021).
SILVA et al. (2021) stated that the objective of genetic improvement in corn is mainly focused on productivity. Currently, the nutritional quality of the grain is not typically considered in a genetic improvement program. In the present study, different cultivars of corn were grown under conditions similar to Brazilian production reality, and correlations among productivity and other variables related to corn quality and feed production cost were assessed. Interestingly, there was a positive correlation (P < 0.05) between crop yield and the final cost of the starter feed for broilers, suggesting that an increase in grain productivity might be related to an increase in the feed cost. This could be explained by the negative correlation (P < 0.05) of crop yield with CP (r = -0.42), dig. Met+Cys (-0.42), and dig. Thr (-0.42), nutrients that have an impact in the feed formulation cost. Such findings are in agreement with previous studies conducted by DUVICK (2005) and ALVAREZ-IGLESIAS et al. (2021), where the negative correlation among grain productivity and nutrients content, especially crude protein, was observed.
The percentage of damage grains and the average contamination of DON and ZEA was not different among the corn hybrids (P > 0.05) whereas contaminations of AFLA and FUM were affected by corn technology (P < 0.05). FUM was the most prevalent mycotoxin, affecting 68% of the crop, with a contamination average of 197 µg/kg. In addition to the nutritional composition of the corn, humidity and temperature conditions are factors that may have influenced this result. The average of AFLA, ZEA and DON were 0.045 µg/kg, 4.08 µg/kg, and 9.11 µg/kg, respectively. The prevalence of FUM observed herein corroborates with previous studies (MALLMANN et al., 2019; SIMÕES et al., 2023) and highlights the current need for reliable information on susceptibility of corn hybrids to Fusarium. In the 2019/2020 crop season, 90% of the corn hybrids available in the Brazilian market lacked data on fusariosis resistance (EMBRAPA, 2021).
The inclusion of AMA in the diet was based on technical recommendations and was directly proportional to the contamination of grains by mycotoxins. The average inclusion of AMA was 0.34 kg/ton of feed, with a maximum of 1.79 kg/ton (Table 3). As expected, the cost of the feed increased as the AMA was added in the diet, and a positive correlation (P < 0.05) was observed between the feed cost and contamination by FUM (0.33) and ZEA (0.29).
Results on nutrients concentration are presented in table 3. Contents of starch, EE, AMEn , CP, dig. Lys, dig. Thr and dig. Met+Cys were different among (P < 0.05) corn hybrids. The average AMEn content was 3,294 kcal/kg with a difference of 81 kcal/kg between the minimum and maximum values. The average CP was 7.8% with a difference higher than 30% between the minimum and maximum values. Such findings are in agreement with previous research (COWIESON, 2005; DOZIER et al., 2011) and reinforce the need to monitor these nutrients in corn, due to the high variability observed and the economic impact it generates.
In order to summarize the results from the present experiment, only the first three limiting AA for poultry are presented; however, all the essential AA established by the NRC (1994) were predicted by NIRS and used in the feed formulations (Table 1). Feed formulation cost presented a negative correlation (P < 0.05) with CP (-0.74), dig. Lys (- 0.66), dig. Met+Cys (-0.73), and dig. Thr (-0.78). This indicates that the lower the level of CP and dig. AA, the higher the cost of the feed, due to the increased inclusion of synthetic amino acids in the formula to supply the AA requirements. In the period of the study, the synthetic amino acids used had costs per kilogram ranging from R$ 3.89 to R$ 8.89. These findings are in line with a study conducted by MALLMANN et al. (2019), which reported that FUM, and CP had a significant effect on the final cost of feed for broiler.
CONCLUSION
Based on the results obtained, we can conclude that the genetic development of corn and modern agricultural techniques have significantly contributed to increasing its productivity. However, the presence of mycotoxins in the grains represents a challenge, raising feed production costs. The variation in corn nutrient levels highlights the importance of closely monitoring its quality. Our findings underscore the ongoing need for research to improve resistance to mycotoxins and the nutritional quality of corn, aiming to ensure sustainability and profitability in animal feed production. Additionally, it is crucial to provide information on the resistance of different corn varieties to diseases such as fusariosis, to assist farmers in choosing the most suitable varieties. This study offers valuable insights to enhance efficiency and safety in animal feed production.
ACKNOWLEDGMENTS
The authors acknowledge the Copacol cooperative for providing the experimental field and assisting in the project’s development. J.K. Vidal, C.T. Simões, and L.M.L. Schlösser are grateful to the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil – Finance Code 001, for providing their graduate scholarship.
DECLARATION OF CONFLICT OF INTEREST
The authors have no conflict of interest regarding the content of this article.
AUTHORS’ CONTRIBUTIONS
All authors contributed equally to the conception and writing of the manuscript. All authors critically revised the manuscript and approved the final version.
This article was originally published in Ciência Rural, Santa Maria, v.54:12, e20230549, 2024. http://doi.org/10.1590/0103-8478cr20230549. This is an Open Access article distributed under the terms of the Creative Commons Attribution License. 
