Amidst the surge in local corn prices over the past three months, coupled with fluctuating supply and demand, feed mills are once again busy searching for alternative materials to alleviate the pressure on corn. Gaplek (dried cassava root) is one such source. Gaplek is derived from cassava tubers, also known as cassava (Manihot esculenta), which are dried naturally in the sun for longer storage. Demand for gaplek is seasonal, inversely related to corn prices. When corn is scarce and prices rise, demand for gaplek increases.
Cassava production, both fresh and processed, such as gaplek (dried cassava root), tapioca flour, starch, and others, is distributed across three sectors: food, animal feed, and industry (pharmaceuticals, textiles, and bioethanol). Use as animal feed reaches 15-20%, mostly in the form of gaplek chips, chunks and meal. For human consumption, processing to maintain cleanliness and appearance is crucial, using sweet varieties with low HCN content.
Conversely, gaplek for animal feed is processed as is; it doesn’t have to use sweet varieties. Bitter varieties (high in cyanide) are also acceptable. This high HCN content can be neutralized by high-temperature heating during the pelleting process. Many dried cassava root for feed are produced in Lampung and East Java, utilizing small-sized cassava that is unsuitable for export or food production to achieve a lower price. The tubers are not completely peeled, dried in the sun, and spread on the ground. Consequently, gaplek often contain skins, soil contamination, and mold due to the high moisture content (>15%).
The main cassava-producing country is Nigeria (57 million tons), while Indonesia will be the fourth-largest producer by 2022 (19.84 million tons), after Brazil (23 million tons) and Thailand (30 million tons). This is not surprising, given Indonesia’s agro-climate, located along the equator, which allows for year-round sunlight to support optimal plant growth. The average sunlight duration is 6-8 hours per day, with even more during the dry season. Cassava plants require an optimal temperature of 25-30°C, air humidity of 60-80%, and ideal rainfall of 1,000-2,500 mm per year. All of these criteria can be met in most parts of Indonesia.
Contents
- 1 Cassava Production in Indonesia
- 2 Main Cassava Producing Areas
- 3 Harvesting and Post-Harvest Handling Gaplek
- 4 Quality control for receiving gaplek
- 5 Nutritional Composition
- 6 Comparison of the nutritional composition of gaplek and local corn
- 7 Proximate composition of cassava products
- 8 Broiler Feed Formulation with Gaplek
- 9 Nutritional profile of Gaplek Chips (as is)
- 10 Formulation strategy for laying hens with gaplek
- 11 Addition of Enzyme in Feed Formulation with Gaplek
- 12 Improving gaplek nutrition through fermentation
- 13 References
Cassava Production in Indonesia
Cassava is drought-resistant and tolerant of less fertile soil, so it does not require intensive fertilization like corn and rice. However, cassava is considered a soil nutrient drainer, producing low levels of organic matter but absorbing more soil nutrients. Without adequate fertilization, production will drop by 30-50% in the second and third plantings. This means that cassava is not recommended as a monoculture, but rather with a crop rotation system (cassava – peanuts – corn) or intercropping (cassava + beans).
Harvest times vary, from 6 to 12 months after planting. Cassava productivity is not linear. This means that the longer the harvest period, the greater the tuber weight, the higher the starch content, and the optimal quality of the resulting cassava. The ideal harvest is 10-12 months after planting, when the tuber weight reaches >90% of its maximum with a starch content of 28-32%. Generally, harvesting can occur year-round due to the rotational planting pattern and variations in harvest times depending on the intended use. The harvest season for cassava production runs from July to November.
Main Cassava Producing Areas
Indonesia’s cassava production in 2022, according to estimates from the Directorate of Agricultural Technology and Food Security at the Ministry of Agriculture, is 14.98 million tons. Seven provinces are cassava production centers: Lampung (39.74%, equivalent to 5.95 million tons), Central Java (16.58%), East Java (9.58%), and West Java (6.91%). The other three provinces—North Sumatra, Yogyakarta, and East Nusa Tenggara—account for 5.87%, 5.43%, and 3.18%, respectively.
Cassava production in Lampung Province reached 7.16 million tons in 2024. Cassava production has shown positive growth (an average of 2.39% from 2014 to 2018) in response to increasing demand. Cassava cultivation is often carried out on marginal land, with minimal inputs. Without sustainable cultivation techniques, it can cause damage to agricultural land.
The main planting season occurs at the beginning of the rainy season, in October-December, so the largest harvest occurs between August and November. Harvests during this period contribute 40-45% of total production, while harvests in November-January and February-July contribute 25-30% each. Harvesting at the beginning of the dry season facilitates the natural drying of cassava, resulting in drier products with less mold contamination and longer storage in feed mill warehouses.
Cassava for animal feed accounts for 15-20% of the total harvest, mostly in the form of chunks, chips or meal. The portion will be bigger and can reach 25% if corn prices rise above IDR 6,500/kg. The largest portion, 45-50%, is used for industrial purposes, primarily to produce tapioca, which is then used as a raw material for other industries, such as the food, textile, and paper industries. Meanwhile, the portion for human consumption is 30-35%, mostly in the form of fresh or processed foods.
Harvesting and Post-Harvest Handling Gaplek
Unlike cassava for human consumption, cassava processing into gaplek for animal feed is done haphazardly to achieve quantity, then quickly sold to farmers or feed mills. Since drying is done naturally, the ideal harvest time is at the end of the rainy season or the beginning of the dry season to optimize drying and reduce the risk of rain during drying. During harvesting, avoid breaking the tubers, as exposed inner surfaces are more susceptible to fungal attack.
During processing, cassava tubers are usually peeled to remove the peel and parenchyma layer. Sometimes the peel remains on the chopped tubers, or in the case of cassava flour, it can be seen as brownish in color, not creamy white. The peel accounts for approximately 15-20% of the total tuber weight.
Depending on the machine used, slices can be 1-2 cm thick and 3-5 cm wide. Meanwhile, the shape of the chunks is usually irregular, with diameters ranging from small to large (>3 cm). If desired, the flour is ground through a smaller sieve, typically a 2-3 mm sieve. If the dried cassava root meal is too fine and dry, it will generate excessive dust during processing in the feed mill. Store in a dry, cool, and well-ventilated warehouse. Important parameters for safe storage include a moisture content of <14%. If the moisture content can be maintained at <13%, it can be stored for 3-6 months. During the rainy season, the moisture content will increase to >15-18%.
Quality control for receiving gaplek
Feed mills can accept gaplek in either meal, irregular small chunks, or chip form. Chunks are cheaper than meal due to the simpler processing. From a production perspective, both chunks / chips and meal have their drawbacks. Fine-ground gaplek can potentially generate excessive dust during the intake process, contaminating the facility and disrupting workers. Chunks vary in size and are not uniform, requiring modifications to the rotary cleaner to reduce wastage and potentially clogging the conveyor belt.
From a quality inspection perspective, it is easier to measure the quality of the chunks because contamination is more easily visible. Considering the potential long-term use of cassava and its prolonged storage in the warehouse, it is important to pay attention to quality during receiving cassava.
The acceptance standards for cassava at feed mills are based on physical and chemical factors. Parameters that are included in the physical are (1) yellowish white or uniform cream color, no excessive black or brown color, (2) fresh, neutral odor, no musty, sour or moldy / putrid odor, (3) dirt ≤1% foreign objects in the form of soil, sand, gravel, skin residue, raffia rope, (4) No mold growth, (5) aflatoxin ≤ 20 ppb, (6) uniform size, according to the purchase agreement, (7) free of lice. Acceptance parameters that are included in the chemical are (1) water content ≤ 14%, (2) starch ≥ 70%, and (3) crude fiber ≤ 5%.
Nutritional Composition
Gaplek cannot completely replace corn due to significant differences in its physical and chemical characteristics. However, it can substitute corn to some extent. Therefore, these differences and limitations must be carefully understood to ensure that substitution does not compromise poultry performance. The quality of gaplek varies significantly depending on harvest age, harvest method, processing, and storage. Deterioration in physical quality, such as musty odor, infestation with mites, mold, contamination by dirt, peel, and other factors, indirectly reduces its nutritional content.
Comparison of the nutritional composition of gaplek and local corn
| Nutrient | Gaplek | Local Corn |
|---|---|---|
| Moisture (%) | 12-13 | 14 |
| Dry matter (%) | 87-88 | 86 |
| Protein (%) | 1.3-2.2 | 7.0-8.0 |
| Fat (%) | 0.4-0.9 | 3.2-4.0 |
| Fiber (%) | 1.8-3.2 | 1.8-2.3 |
| Ash (%) | 0.9-1.8 | 0.9-1.3 |
| Starch (%) | 66-75 | 56-62 |
| AME (kcal/kg) | 2800-2900 | 3100-3200 |
| Calcium (%) | 0.04-0.09 | 0.02-0.03 |
| Total Phosphorus (%) | 0.04-0.09 | 0.22-0.26 |
| Lysine (%) | 0.03-0.04 | 0.22-0.25 |
| Methionine (%) | 0.02-0.03 | 0.17-0.20 |
Gaplek is almost entirely carbohydrate (85-90% dry matter), with more than 90% of this carbohydrate being starch. Although its starch content is higher than that of corn, its low fat content makes it less metabolizable than corn. Fat contributes 2.25 times more energy than starch. Gaplek starch is relatively easy to digest and, therefore, very efficient at converting into energy. Low fat levels also indicate low levels of fat-soluble vitamins such as vitamins A, B1, B2, and niacin.
Compared to corn, the structure and chemical composition of gaplek starch differ, which is low amylose and high amylopectin. Its lower pelleting ability is due to its high amylopectin content, as amylopectin tends to form a thick, brittle paste with less elasticity. The very low fat content makes the feed mixture harder and drier during in conditioning. This results in higher friction in the die, weaker binding strength, and more easily crushed pellets. More gaplek portions in the formula require more moisture during conditioning.
Although this contradicts some research findings that suggest otherwise. Gaplek starch is thermoplastic; during conditioning (80-85°C), the starch undergoes partial gelatinization, which increases the pellet durability index (PDI). Pelleting capacity will increase because less flour needs to be re-pelleted, and the feed material flows more easily through the die holes.
With a protein content of only 1-3%, cassava is inferior to corn in terms of protein and amino acids. Lysine and methionine content are almost zero. Using large amounts of cassava will not significantly contribute to protein and amino acid supply, due to its low protein quality. Amino acids such as lysine, methionine, threonine, isoleucine, cysteine, phenylalanine, and proline are particularly low. Conversely, arginine is relatively high.
In terms of macro minerals, the calcium content of cassava and corn is relatively similar, while the phosphorus content of corn is 3-4 times higher than that of cassava. The low total phosphorus content must be compensated for by the addition of DCP or MCP to prevent phosphorus deficiency. Micro minerals, such as iron and zinc, are present in very small amounts in cassava, which is typically grown in soils with low fertility, little fertilization, and mineral and vitamin deficiencies.
Gaplek contains antinutrients, primarily hydrocyanic acid (HCN), bound in a non-toxic glycoside called linamarin. When the tubers are processed, linamarin comes into contact with the enzyme linamarase, hydrolyzing them and releasing toxic HCN. Fortunately, HCN is volatile and readily soluble in water, so the drying and washing / steaming processes significantly reduce the HCN content. After being processed into cassava, the HCN content is expected to remain below 10 ppm, which is safe for poultry. Bitter varieties of cassava contain around 310 mg/kg of HCN, while sweeter varieties have a much lower HCN content (38 mg/kg).
Proximate composition of cassava products
| Cassava products (%) | Dry matter | Protein | Fiber | Fat | NFE | Ash | Ca | P |
|---|---|---|---|---|---|---|---|---|
| Peel | 28.76 | 5.36 | 15.83 | 1.60 | 68.12 | 6.05 | 0.35 | 0.16 |
| Peel meal | 87.59 | 5.33 | 14.23 | 1.81 | 70.38 | 5.51 | 0.65 | 0.25 |
| Root | 39.24 | 2.62 | 3.58 | 0.90 | 82.55 | 2.98 | 0.20 | 0.23 |
| Root meal | 89.42 | 3.10 | 3.73 | 0.98 | 82.77 | 3.88 | 0.16 | 0.37 |
| Leaf | 43.05 | 19.82 | 12.89 | 7.92 | 44.96 | 7.40 | 2.10 | 0.84 |
| Leaf meal | 92.06 | 23.79 | 17.70 | 6.83 | 40.58 | 8.07 | 1.24 | 0.60 |
| Starch | 79.44 | 1.16 | 6.92 | 0.13 | 72.49 | 1.08 | 0.01 | 0.01 |
| Pulp | 89.78 | 2.53 | 16.10 | 1.61 | 52.84 | 3.11 | 0.05 | 0.04 |
| Pellet | 88.70 | 5.84 | 10.83 | 1.02 | 69.53 | 4.49 | 0.48 | 0.17 |
| Flour | 85.35 | 1.79 | 1.93 | 0.66 | 78.77 | 1.62 | 0.04 | 0.36 |
| Chips | 89.43 | 2.36 | 3.49 | 1.20 | 82.09 | 2.60 | 0.17 | 0.11 |
| Source: Natalie K Morgan and Mingan Choct, 2016 | ||||||||
Broiler Feed Formulation with Gaplek
Energy is the most expensive in feed formulation. As the government implements a basic purchase price of IDR 5,500/kg for corn from farmers on a maximum 14% moisture content, corn prices will fluctuate upwards. As corn prices rise, other energy-based raw materials will sooner or later follow suit. Poultry feed formulations must find a balance to achieve the most economical combination of raw materials. Lower-priced alternative raw materials should be used as a substitute for corn.
Gaplek is currently cheaper and in sufficient supply, making it a viable substitute for corn. Considering that broiler feed requires higher energy than layer feed, the use of gaplek in broiler feed formulations will significantly reduce feed costs. Gaplek’s energy content is 10-12% lower than corn, so it needs to be compensated with additional oil sources such as palm oil (CPO). The use of CPO is also beneficial for maintaining feed palatability.
The maximum use of gaplek varies depending on the age of the chicken. During the first 10 days, the digestive system is still underdeveloped, with amylase and protease enzymes low. Although cassava starch is easily digested, chicks are highly dependent on protein-derived energy (amino acids) for organ growth (the digestive system, intestines, and pancreas). As cassava protein is very low, and high substitution can lead to lysine and methionine deficiencies. Broiler chicks are also more susceptible to HCN (<10 ppm), which is an anti-nutritional nutrient. It is recommended that cassava usage be limited to 10-15% in the starter phase, with amino acid balance and additional oil.
The use of gaplek can be increased to 20-25% in the 11-24 day (grower) phase. This is because broilers are more tolerant to HCN toxicity during this phase, and amylase enzyme activity has increased significantly, although not yet at its peak, compared to finishers. When broilers enter the finisher phase (25-harvest), amylase activity has peaked, enabling the digestive system to efficiently digest cassava starch.
At this stage, the gaplek inclusion can be increased to 30-40% in broiler feed formulations, provided with excellent quality gaplek. They are now more tolerant of antinutrients such as HCN because their liver and detoxification enzymes (rhodanese) are well developed. The use of gaplek >50% has negative effects, including decreased feed intake, growth rate, and worsening FCR, as has been confirmed by numerous studies.
Similar to corn, gaplek, when used moderately at 30%, has a low digesta viscosity (2.5-4.5 cP or centipoise). Its low soluble fiber content means that when it comes into contact with water in the digestive tract, it does not absorb water and subsequently expands, making the solution thicker, forming a gel-like network structure. The viscosity of gaplek remains low because almost all of its fiber is insoluble. The use of gaplek does not pose a risk of wet litter (due to its high viscosity) and does not adversely affect the gut microbiota.
Nutritional profile of Gaplek Chips (as is)
| Nutrient | Value |
|---|---|
| Dry matter (%) | 86.80 |
| AME, kcal/kg | 2990 |
| Fat (%) | 0.11 |
| Fiber (%) | 3.70 |
| Protein (%) | 4.37 |
| Arginine (%) | 0.17 |
| Histidine (%) | 0.06 |
| Isoleucine (%) | 0.12 |
| Leucine (%) | 0.19 |
| Lysine (%) | 0.16 |
| Methionine (%) | 0.04 |
| Phenylalanine (%) | 0.11 |
| Threonine (%) | 0.11 |
| Tryptophane (%) | 0.04 |
| Valin (%) | 0.15 |
| Ca (%) | 0.23 |
| P (%) | 0.15 |
| K (%) | 1.29 |
| Mg (%) | 0.12 |
| Na (%) | 0.05 |
| Cu (ppm) | 3.49 |
| Mn (ppm) | 24.71 |
| Zn (ppm) | 11.50 |
| Source: Sudhir Yadav, Birendra Mishra, and Rajesh Jha, 2019 | |
Formulation strategy for laying hens with gaplek
The most potentially detrimental effect of using cassava in laying hen feed is its effect on the egg yolk color, which becomes paler. This is due to the lack of carotenoid pigments, which are practically non-existent in cassava. Egg yolk color is influenced by the yellow pigments lutein and zeaxanthin, along with the reddish-orange pigments canthaxanthin and capsanthin. Corn contains 15-30 mg/kg of lutein and zeaxanthin, while cassava contains <0.5 mg/kg. Adding synthetic canthaxanthin can help prevent pale yolks. A dose of 0.5-2 ppm can be useful for maintaining yolk color at Yolk Color Fan (Roche) ≥10.
The use of 15-25% cassava in laying hen feed does not adversely affect egg production or egg quality. Concentrations above 25-50% will result in decreased feed intake and egg production. Feed should be pelleted because mash feed with a high cassava content will generate a lot of dust and reduce feed intake. Meanwhile, pelleting (heating) will reduce HCN levels.
Although the protein content of layer feed (in production) is quite low (16-18%), the very low protein and amino acid content of gaplek itself requires more rigorous reformulation. Lysine and methionine are particularly important, as they are crucial for egg production and overall performance. Supplementation with synthetic methionine (0.2-0.3%) and synthetic lysine (0.1-0.2%) is recommended to meet nutritional needs. Furthermore, adequate supplementation of total sulfur amino acids (Met + Cys) (0.65-0.75%) is required at high levels of gaplek to help detoxify cyanide. The balance of Met and Cys is approximately 60:40. If Cys is low, methionine will be metabolized to cystine, increasing methionine requirements and reducing efficiency.
Fat-soluble vitamins such as A, D, E, and K, as well as B-complex vitamins (thiamine, riboflavin, and niacin), are relatively low in gaplek. All of these must be taken into account in reformulation to meet daily requirements and in accordance with the strain’s supplementation recommendations. If necessary, use a single vitamin to compensate for deficiencies.
Macro minerals, especially calcium and phosphorus, are also present in low amounts. An unbalanced Ca/P ratio will negatively impact shell quality (shell thickness and strength). Supplementation with adequate amounts of vitamin D3 and zinc will help improve shell quality, especially if gaplek is used in large quantities to replace corn.
Addition of Enzyme in Feed Formulation with Gaplek
Gaplek is classified as a non-viscous raw material due to its very low soluble fiber content (water-soluble fiber content) of <1% (0.3% to be exact), and very little arabinoxylan, beta-glucan, or mannan. Under these conditions, the gaplek itself does not require the addition of xylanase, beta-glucanase, or mannanase enzymes. Gaplek starch is easily gelatinized and has high digestibility, so adult chickens do not require amylase supplementation because their endogenous amylase levels are sufficient. Adding amylase to feed containing >15% gaplek for chicks is acceptable, especially if the quality of the gaplek used is not fully dried (moisture content >= 14%).
Phytase enzymes are routinely added to poultry feed, but this is unrelated to the use of gaplek as a corn substitute. Since gaplek does not contain phytate, no P is released. Meanwhile, other raw materials used, such as SBM, rice bran, and others, have high phytate content, requiring phytase enzymes. Phytase becomes more efficient because the phytate-free cassava eliminates excessive substrate interference. Phytase (500-1000 FTU/kg) can be optimized to work with other raw materials. The addition of phytase increases the availability of P, Ca, Zn, and Fe because phytate binds minerals. It also increases the availability of protein and amino acids because phytate inhibits protease.
The protein content of gaplek is very low (<5%), so if protease enzymes are added to the feed, they are more intended to work on macro-protein sources such as SBM, DDGS, CGM, CGF, local feather meal, and others.
Improving gaplek nutrition through fermentation
Gaplek fermentation provides the following benefits: (1) Fermentative microbes such as Saccharomyces, Rhizopus, and Lactobacillus degrade cyanogenic compounds, converting them into non-toxic CO2 and NH2 compounds that are safe for poultry. (2) During the fermentation process, the growing microbes form single-cell proteins that increase the protein content of gaplek. (3) Fermentative microbes produce the enzymes amylase, protease, and phytase, which break down crude fiber, complex starch, and phytate, thereby increasing the availability of energy and phosphorus. (4) Fermentation adds probiotics and their metabolites, organic acids, which support digestive health.
The fermentation process uses finely ground dried gaplek, added with commercial inoculants such as Saccharomyces cerevisiae combined with Lactobacillus spp. or Aspergillus niger. Nitrogen supplements such as 0.5-1% urea or 5-10% soybean meal can be added to enhance microbial growth and also increase the final protein content. Sufficient clean water is added to achieve a fermentation water content of 50-55%, so that the dough is sufficiently moist.
Fermentation occurs aerobically and takes 48-72 hours. It can be as short as 24-48 hours, depending on the type and dosage of inoculum used (a dose of 1-2% S. cerevisiae is faster). The incubation temperature must be maintained at an optimal 32-37°C, stirring to provide aeration (oxygen), and adding a nitrogen source to provide N for microbial protein synthesis. The dough temperature should not exceed 45°C, as this will kill the microbes.
Fermented gaplek contains more than 10% protein, with a 10-20% reduction in crude fiber compared to raw cassava, and cyanide levels below 10 ppm, which is safe for poultry. Organoleptically, fermented gaplek has a fresh, sour odor similar to cassava ‘tape’, with no musty odor, and a mild, sour taste that is not bitter or rancid. If it has a foul odor, a strong acidity, or a greenish color, the fermentation is considered unsuccessful. Such products should not be fed to poultry.
The use of fermented gaplek (with S. cerevisiae) up to 20% in broilers resulted in a growth rate that was not significantly different compared to the control feed (Le Duc Thao et al., 2025). Furthermore, fermented gaplek (with bacteria from rumen filtrate) up to 45% did not have a detrimental effect on broiler body weight gain or feed conversion compared to the control feed (Gerald Kizito et al., 2025). Research by Pido et al. (1979) using 50% fermented gaplek did not result in differences in production performance and carcass characteristics. On the other hand, feed costs were reduced.
References
- Anaeto M and Adighibe, LC. Cassava root meal as substitute for maize ion layers ration. Brazilian Journal of Poultry Science. v.13 n.2 page 153-156. Apr – Jun 2011.
- Edwin Peter Chang, Medani E. Abdalih, Emmanuel U Ahiwe, Said Mbaga, Ze Yuan Zhu, Fidelis Fru-Nji and Paul A de Iji. Replacement value of cassava for maize in broiler chicken diets supplemented with enzymes. Asian-Australas J Anim Sci. 3;33(7): 1126 – 1137. Aug 2019.
- Gerald Kizito, Antony Macharia Kingori and Fred Kemboi. Growth performance and carcass traits of broiler chicken fed on diets containing rumen filtrate fermented by cassava meal. Journal of World’s Poultry Science Vol. 4 No. 3. 2025
- Le Duc Thao, Phan Thi Hang, Zabransky Lubos and Duong Thanh Hai. Growth Performance, Meat Quality and Economic Efficiency of chickens fed fermented cassava root by Saccharomyces cerevisiae. Journal of Animal Health and Prod. Vol. 13, Iss. 4. pp.1046-1054. 2025
- Maidah Dwi NS, Mas’ud dan Sri Wahyuningsih. Analisis kinerja perdagangan ubi kayu. Vol 12 No 2A. Pusat Data dan Sistem Informasi Pertanian, Kementerian Pertanian. 2023.
- Nadia Putri A, Budhi Gunawan dan Junardi Harahap. Ekologi politik budidaya singkong di Kecamatan Arjasari Kabupaten Bandung Provinsi Jawa Barat. Aceh Anthropological Journal, Vol 6, No. 2, 137-151. Oktober 2022.
- Natalie K. Morgan and Mingan Choct. Cassava: Nutrient composition and nutritive value in poultry diets. Animal Nutrition 2, page 253 – 261. 2016. Journal homepage http://www.keaipublishing.com/en/journals/aninu/
- Pido, P.P, S. A. Adeyanju, and A. A. Adegbola. The effect of graded levels of fermented cassava meal on broilers. Poultry Science 58:427-431. 1979.
- Sudhir Yadav, Birendra Mishra, and Rajesh Jha. Cassava (Manihot esculenta) root chips inclusion in the diets of broiler chickens: effects on growth performance, ileal histomorphology, and cecal volatile fatty acid production. Poultry Science 98: 4008 – 4015. 2019.
