Scope of Protein Alternates in Poultry Feeds

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Introduction
By 2050, there will be huge proatein demand in the global food system for the projected 10 billion people. Soybean meal (SBM) and fish meal (FM) remain the primary conventional protein sources for poultry feed. The cost of conventional proteins like SBM and FM is increasing continuously. Also, the production of soybean is connected with deforestation, soil erosion, eutrophication, extensive use of pesticides, loss of biodiversity, and a huge carbon dioxide (CO2) footprint. Recently, increasing soybean price has challenged the economic sustainability of the poultry meat industry, mainly in developing countries. Besides, many countries have either banned (e.g., meat and bone meal-MBM) or limited (e.g., fishmeal) the inclusion of valuable conventional protein sources of animal origin in livestock feed. Although soybean production has increased substantially over the past two decades to meet the rising demands, a gap between soybean production and consumption is seen around the world. Alternative protein sources are therefore the need of the hour to make poultry production a sustainable production system in the future. Therefore, to meet the future requirements of protein, new protein sources may be explored. Affordability, accessibility, and ease of processing for the poultry industry make these alternate protein sources more attractive for feed formulation. Hence, the availability of high-quality and low-price protein sources are important elements to maintaining poultry production competitively and continuing to provide animal protein for human consumption. This review aims to explain the scope of alternate protein sources which not only bridge the gap of protein need but also pave the way for sustainable poultry production that is used with modern feed additives and processed properly.
Protein Alternative Sources
Protein source for poultry feed comes from an animal, plant, and insect protein origin. In general, animal-based protein sources are high-quality proteins due to their high digestibility, biological value, and rich amino acid profile than plant-based protein sources. By using exogenous enzymes and proper processing, plant-based proteins can be converted into more digestible proteins with a good amino acid profile. Insect proteins are good in essential amino acid content and protein digestibility. Many studies have established the concept that insect proteins are well accepted by animals and 25–100% of soymeal or fishmeal can be easily replaced by insect protein.
Plant-based and insect-based proteins

• Rapeseed meal (RSM) or Deoiled Mustard Cake
• RSM is a by-product of rapeseed having high protein (34%–38%) with a well-balanced amino acid profile and can be used in poultry diets
• RSM usage is limited due to ANFs, glucosinolates (GLS), and erucic acid

• Solid-state fermentation by microorganisms like Bacillus subtilis and Lactobacillus has been used to increase the bioavailability of nutrients and reduce the level of ANFs of rapeseed meal
• A study has shown that growth performance, antioxidant capacity, and meat quality of broiler chickens got improved by replacing SBM with fermented RSM, which can be used as a suitable alternative protein source in broiler chicken diets
• Furthermore, breast meat fatty acid profile was improved, and methane emission was limited
• Studies showed that using solid-state fermented rapeseed meal improved body weight gain (BWG) and feed conversion ratio (FCR) when compared to broilers fed unfermented rapeseed meal but did not differ from the SBM control
• Genetically, a selected and developed variety of rapeseed has reduced GLS and erucic acid
• Many studies have shown that genetically selected RSM is the cost-effective substitute for soybean meal for poultry and has greater standardized ileal digestibility of amino acids (AA) when compared with RSM to be used in broiler diets

Duckweed (Lemnacae/Water Lentils)

• Duckweeds are free-floating aquatic plants and have a high protein content of 20–40%
• Duckweed protein has higher concentrations of essential amino acids, lysine, and methionine than most plant proteins, and more closely resembles animal protein in that aspect
• Study suggested that a small amount (6% dry matter basis) of fresh or dry Duckweed can be incorporated for profitable broiler production
• According to researchers, the contribution from duckweed as a protein source should not exceed 6% in grower and finisher stage feed for broilers

Moringa Oleifera Leaves (MOL)

• Common names of Moringa oleifera include moringa, drumstick tree, horseradish tree, ben oil tree or benzoyl tree, or miracle tree
• MOL have antimicrobial roles and are rich in fats, proteins, vitamins, and minerals
• Nutritional composition of MOL (dry matter basic) contains dry matter (DM) (93.63-95.0%), crude protein (17.01-22.23%), carbohydrate (63.11-69.40%), crude fiber (6.77-21.09%), crude fat (2.11-6.41%), ash (total mineral) (7.96-8.40%), gross energy (14.790 MJ/kg), and fatty acid (1.69-2.31%)
• Moringa oleifera has been used as a growth promoter, immune enhancer, and antioxidant and has a hypo-cholesterol effect on chickens
• A higher body weight was recorded on using moringa leaf powder as a dietary supplement with 1.2% levels in broilers
• Diets supplemented with moringa leaf meal could improve the growth performance at the finisher period, and are used as a natural source of protein in broiler diets
• Similarly, the inclusion of MOL at higher levels in broiler diets resulted in a higher growth rate and better health status in broilers
• Many studies suggested a recommendable inclusion level of M. oleifera up to 10% in both broilers’ and laying hens’ diets

Cottonseed Meal (CSM)

• CSM is valued as a protein feed, but the protein content is highly variable as it depends on the extent of dehulling and efficiency of oil extraction
• The main constraint of CSM is the presence of gossypol, which limits its use in non-ruminant animals such as pigs and poultry
• Gossypol toxicity can be alleviated through the addition of iron salts and solid-state fermentation
• Low or no gossypol cultivar is well tolerated by broilers
• With adequate supplemental lysine, CSM can be used in broiler diets without a reduction in performance
• CSM in combination with lysine-rich supplements had shown the potential to replace up to 40% of SBM protein in broiler diets without any negative effects
• In layer diets, the use of CSM is restricted due to the effects of cyclopropenoid fatty acids on internal egg quality
• Diet containing CSM at 20% as the major protein source improved flock body weight, uniformity, and reproductive performance of broiler breeder pullets

Sunflower Meal (SFM)

• SFM has some factors that may limit its use in bird feed, such as low concentration of lysine, presence of phytates and chlorogenic acid, high fiber, and non-starch polysaccharide (NSP) content
• The negative effect of chlorogenic acid can be reduced by adding methionine and choline to poultry diets
• Wheat soybean meal-based diet containing 50g/kg SFM for starter and 80g/kg SFM for grower/ finisher along with enzyme (xylanase & beta-glucanase) supplementation resulted in no negative effect on broiler performance and carcass characteristics
• Exogenous enzyme along with digestible lysine supplementation to a low-density broiler diet containing SFM improved BW gain and gain: feed ratio during 1–21 days
• Recently, with the advanced technology, processing of dehulled SFM yielded a high-protein SFM (HiSFM), whose protein content may reach an average of 46%
• Researchers found that sunflower cake (SFC) inclusion of up to 210g SFC/kg feed for growing brown-egg laying pullets was not enough to cause harmful effects on the performance of birds, and inclusion of up to 200g SFC/kg feed for growing white-egg laying pullets did not affect the performance of growth and laying phase

Rice Distillers Dried Grains with Soluble (DDGS)

• Rice DDGS is a co-product of the ethanol industry produced during the dry milling process
• Addition of rice DDGS at a 10% level gives the best result for economic broiler production
• Study has concluded that rice DDGS added up to 100 g/kg of laying hen diet along with enzyme had significantly (P<0.01) improved the egg mass, egg production, and feed conversion ratio per dozen eggs
• Another study concluded that rice DDGS can be safely incorporated in the broiler chicken diet up to an inclusion level of 12.5% as an alternate protein meal but due to commonly observed high level of deviations in protein content, it may be ideal to include no more than 4-5 % based on the degree of variation

Groundnut Meal / Peanut Meal (GNM/ PNM)

• Groundnut meal is deficient in lysine, threonine, and methionine, but the main constraint to its utilization is its easy contamination by aflatoxin
• Birds placed on a 25% GNM-based diet consistently had higher relative carcass and organ weights than those fed with a control diet
• Peanut meal has more arginine content than soybean meal
• When threonine was added to the corn-PNM diet, BWG and FCR got improved when compared to the diet without threonine. Hence, in certain economic conditions, PNM can be used as an alternate protein source for broilers. The addition of 0, 0.1, 0.2, and 0.3% threonine to a corn-PNM-based diet increased BWG from 0 to 18 days and decreased
• FCR compared to a corn-SBM-based control diet.

Insect Protein
Silkworm Pupae (SWP) Meal

• Silkworm pupae meal is a protein-rich feed ingredient with high nutritional value. Its CP content ranges from 52 to72%, while for the defatted meal, it can be higher than 80%
  Experiments revealed that replacing 50% (by weight basis) of the main protein source (mostly fishmeal) with silkworm meal is usually safe, though mineral supplementation may be required
• Normally, inclusion rates are typically in the range of 5-10%
• Silkworm meal replaced fishmeal without adverse effects, and the best performance was obtained with 50% replacement of fishmeal by silkworm pupae and supplemented with enzymes
• Laying chickens fed on silkworm pupae had lower FCR, high BWG, and egg production percentages
• Deoiled SWP meal improved the shelf life and feeding efficiency
• A broiler diet formulation containing control diet (6% FM + 0 SWP) and three treatment diets (4% FM + 2% SWP; 2% FM + 4% SWP and 0% FM + 6% SWP) reported an increase in BW (1274.24, 1425, 1440.15 and 1474.99 g/bird, respectively at 42d of age), FCR (2.25,1.95, 1.93 and 1.88, respectively), dressing percentage (58.75,68.15, 69.37 and 73.0, respectively) and profitability (0.15,0.19, 0.21 and 0.22 US$/kg broiler, respectively) linearly on the increasing levels of SWP
• Black Soldier Fly (BSF) Larva Meal / Hermetia Illucens (HI) Meal
• Black soldier fly larvae (BSFL) are a high-value feed source, rich in protein and fat, which contains about 40–44% crude protein
• BSF larvae have replaced 100% of fishmeal in layer diets with no impact on egg production
• In male broiler chickens, an increasing level (50, 100, and 150 g/kg) of defatted dietary Hermetia illucens meal inclusion improved the live weight and dietary feed intake during the starter period
• Linear and quadratic responses were observed for increasing HI meal levels in the live and carcass weights (P < 0.001), with a maximum of 100g/kg group
• Results suggest that H. illucens larva meal is a suitable substitute for SBM in the diet of Lohmann Brown Classic laying hens
• Feeding dried BSF larvae as a substitute for SBM resulted in a similar BWG but a lower feed intake when compared to control indicating an improved FCR
• As the ash percentage and heavy metal are more in BSFL, it must be used as per the inclusion level
• BSFL are a good source of lysine, oil, and fatty acids that imparts reddish coloration to egg yolk
• It also increases the immunity of the gut by increasing IgA and IgY and decreasing tumor necrosis factor (TNF) alfa

Earthworm Meal (EWM)

• Earthworms are natural protein sources for chickens with currently no competition for other uses
• EWM has higher concentrations of essential amino acids such as lysine
• Broiler chickens fed with a diet containing 3% EWM showed an increase in BWG (1.176 kg/broiler chicken) with the least FCR
• The acceptability level of earthworm meal in the broiler diet is lower than 15%
• Replacement of SBM and FM partially with EWM in broiler diets with five different treatment groups (0, 5, 10, 15, and 20% EWM) showed significant (P<0.05) BWG and FCR of 10% (2089 g and 1.99, respectively) and 15% (2087 g and 1.94, respectively) EWM groups than the control group (1928 g and 2.08) without much effect on feed intake (FI)
• Another study on broiler improved FCR by 13% and 22%, with a diet containing 3% and 5% earthworm powder, respectively, in comparison to a 0% and 1% earthworm powder diet

Conclusions
Understanding the alternative ingredient usage is crucial for maximum utilization and successful feed formulation. It is possible to improve the quality of these alternative protein sources through processing, genetic selection, and supplementation with nutrient and non-nutrient additives such as enzymes in order to improve their utilization by poultry. Multiproteases from Kemin contain three different proteases for better enzyme-substrate reaction and sustained activity throughout the gut, are equally effective on both animal and plant-based alternate proteins in increasing digestibility, improving the amino acid profile, and alleviating ANFs. For sustainable and competitive production of poultry meat, focusing on regionally available alternate protein sources is vital. Protein alternative sources should be used judiciously based on different phases of poultry growth, as feed consumption increases the requirement of amino acids and gradually comes down with age. In challenging disease outbreak periods, nutritionists may consider alternatives that have an immunity-enhancing role, rather than focusing only on growth and/or performance. A conservative approach is required when dealing with alternatives, but with a suitable laboratory analysis facility, next level of inclusion can be followed for better realization of cost savings.
Note: References available on request.

by Dr. Ajay Kumar, Dr. Partha Das, and Dr. Venket M Shelke
Kemin Industries South Asia