Advantages of quality protein maize use in broiler dietsABSTRACT:
Meat consumption has been declining in favor of a shift towards poultry due to its lower price, health benefits and consumers’ preference. One of the ways to enhance broiler production and quality is to substitute standard maize (SM) with quality protein maize (QPM) in animal diets. QPM is a high lysine maize with improved nutritional and biological values, developed by the selection of a naturally occurring recessive opaque2 mutation, which can reduce the use of costly feed components - synthetic lysine and protein ingredients such as soybean and fishmeal. Different feeding trials with QPM in broiler diets indicated that body weight gain (BWG), feed conversion ratio (FCR), breast meat yield (BMY), and abdominal fat (AF) are the main improved features. Herein, an overview of the effects of QPM on broiler performance and carcass characteristics, as well as the financial effects of its use, is presented. Different effects of QPM were observed, depending, in the main, on the QPM hybrid used in the trial. The possible reasons for the discrepancies and suggestions for overcoming them, focused on the utilization of the full potential of QPM, are discussed.
Keywords: cost-effectiveness; essential amino acids; high lysine maize; poultry
Introduction
Maize (Zea mays L.) is considered a favored energy source in poultry diets compared to other cereals owing to its high energy, low fiber and essential fatty acids contents, high palatability, and digestibility (Panda et al., 2014). This cereal can contribute approximately 65 % of the apparent metabolizable energy and 20 % of the crude protein to a broiler diet (Cowieson, 2005). However, the quality and quantity of maize protein and essential amino acid (EAA) content must be improved for optimal broiler chicken performance. Soybean meal is a favored protein source due to its high protein content and excellent amino acid profile (Dei, 2011). However, excessive heat treatment during soybean processing causes EAA, especially lysine, to become unavailable. In order to provide optimal lysine requirements for broiler growth and development, diets are supplemented with synthetic Dextrorotatory/Levorotatory (DL)-lysine. Today, quality protein maize (QPM) with increased lysine content developed using a naturally occurring opaque2 mutation can be used to reduce the use of costly synthetic amino acids and soybeans in broiler diets (Khan et al., 2020).
The goal of this review is to summarize current experience on the effects of substituting standard maize (SM) with QPM in broiler diets on their body weight gain (BWG), feed conversion ratio (FCR), breast meat yield (BMY), and abdominal fat (AF); performance and carcass characteristics of major interest to the livestock industry (lower production costs), broiler producers (better performance of broilers) and consumers (healthier food - low caloric value and lower portion of saturated fatty acids). At the same time, the summarized results from different experiments are discussed, focusing on the utilization of the full potential of QPM. This is important for several reasons. Firstly, QPM is high in lysine, and the second limiting EAA in broilers, crucial to protein synthesis and muscle building. Secondly, compared to SM, QPM is superior in protein quality and digestibility (Panda et al., 2014) and has higher contents of other EAA, minerals, provitamin A and E, and anti-oxidative capacity (Joshi et al., 2022). Finally, QPM (maize of tropical and sub-tropical origin) adapted to temperate regions has been developed, opening up possibilities for its use in the livestock industry in developed countries. Thus, an overview of the selected papers can identify benefits and drawbacks and provide guidelines for future research and implementations that could contribute to production sustainability and food safety.
Literature search methodology
For the literature survey, the electronic databases Scopus, Google Scholar, PubMed and Web of Science were systematically searched for papers published in the last 15 years (2009-2023). Basic keywords used were QPM and broilers, in different combinations with other relevant words such as diets, performance, and carcass characteristics. A total of 21 papers were found. Eighteen research papers addressed broiler performance and carcass characteristics (15 full articles and three abstracts), while seven papers focused on the financial benefits of using QPM in broiler diets, with four covering both experimental results and economic analyses. The literature search showed limited studies on the utilization of QPM in broiler diets under varying conditions. Nonetheless, recent research has confirmed interest in the performance and cost benefits of broiler chickens fed with QPM as the replacement for standard maize (Almajiri et al., 2023; Elangovan et al., 2022; Thapa et al., 2021). A detailed review of the effects of QPM on BMG, FCR, BMY, and AF was elaborated, and the main results found in the articles were synthesized and discussed.
Quality protein maize – QPM
Maize is one of the world's most important protein sources; however, like all cereals, it has low nutritional quality due to poor EAA lysine and tryptophan content in the dominant seed storage protein fraction, zeins. The improvement in maize protein quality was achieved with the discovery of the naturally occurring recessive opaque2 (o2) mutation (Mertz et al., 1964). The opaque2 gene encodes the bZIP family transcription factor, which regulates zein gene families through binding to a general control of nitrogen 4 (GCN4)-like motif (aka O2-box) (Li et al., 2015). Zeins are the major storage proteins in maize endosperm, classified as α-zeins (19 and 22 kD), β-zeins (15 kD), γ-zeins (16, 27, and 50 kD) and σ-zeins (10 and 18 kD). It has been shown that different families of zein genes are downregulated in o2 genotypes to different extents and that the most dramatically downregulated gene family was the 22-kD α-zein family (Zhan et al., 2018). In other words, the mutant o2 gene greatly reduces the storage of zein proteins poor in lysine content and increases non-zein proteins, which have high lysine content and a balanced proportion of EAA.
In addition to storing protein gene expression, opaque2 regulates genes involved in a diverse biological functions and processes, including the synthesis and metabolism of carbohydrates and lipids (Hartings et al., 2011; Li et al., 2015). The pleiotropic effects of o2 lead to the formation of kernels with a soft/starchy endosperm, which increases susceptibility to pathogens and causes low yields. However, breeders from the International Maize and Wheat Improvement Center (CIMMYT), Mexico, through conventional breeding programs, have developed agronomically acceptable and nutritionally improved o2 types named quality protein maize (Vasal, 2000; Vivek et al., 2008).
Quality protein maize has grain with up to twice the amount of lysine and tryptophan compared to SM. Moreover, QPM has superior protein quality and protein digestibility - the biological value of standard maize is 5 % compared to 80 % of QPM, with 37 % of standard maize protein intake being utilized compared to 74 % of QPM (Kareem-Ibrahim et al., 2021). The quality of QPM protein is like that of milk at 90 % due to a nitrogen balance index comparable to that of milk (Jilo, 2022). Other nutritive advantages of bio-fortified QPM include higher mineral content with potassium, calcium and zinc, higher provitamin A and E, as well as higher anti-oxidative capacity due to the high content of phenols and flavonoids (Joshi et al., 2022).
Although QPM is of tropical origin, and the retained exotic germplasm frequently hampers its adaptation to temperate regions, there are promising reports on QPM adaptation that contribute to food and nutritional security solutions under irrefutable climate changes and human population growth. Nine QPM lines, recognized as good candidates for nutritive enhancement of feed maize, were developed jointly by Iowa State University and the Agricultural Research Service of the United States Department of Agriculture to address the lack of QPM lines adapted to the US Corn Belt (Worral et al., 2015). QPM genotypes were successfully adapted to short-season environments at North Dakota State University, and, as a result, new North Dakota EarlyQPM germplasm and lines were developed for potential release (Carena and Dong, 2017). The Maize Research Institute Zemun Polje (MRIZP) has a long-term program for developing QPM adapted lines and hybrids targeting the feed industry, and the first successful results have already been attained (Ignjatović-Micić et al., 2020; Kostadinović et al., 2016). The aforementioned works highlight the relevance of QPM to the development of the next generation of value-added crops for managing the increasing need for nutritionally enhanced food and feed.
Quality protein maize was primarily developed for human consumption to overcome malnutrition in countries where maize is a staple food and a principal source of protein. Several deficiency symptoms, such as kwashiorkor (a protein deficiency illness), low appetite, cognitive disorder, impaired skeleton, and reduced growth rate are linked to tryptophan and lysine deficiencies (Maqbool et al., 2021). It has been shown that regular intake of QPM can reduce the symptoms of these illnesses (Joshi et al., 2022). In addition to its importance as food, QPM can be used as a component of livestock feed, especially in developed countries where 78 % of total maize production is used for feed (Sofi et al., 2009). In this review, the use of QPM in broiler diets was analyzed since, according to FAO (2021), global protein availability from poultry meat is projected to grow by 17.8 % by 2030 compared to the base period average of 2018-2020, much more than from other meats. Meat consumption has been shifting towards poultry due to its lower price than other meats in developing countries and an increased preference for white meats which are perceived as a healthier food choice in developed countries.
Effects of dietary QPM on broiler chickens
Although the experiments presented in the reviewed papers differed in certain aspects, such as protein sources and duration, all diets used were formulated to meet the nutritional and energy needs of broiler chicken (data not presented). According to the authors, uniform management and vaccination schedules were followed. The diets were offered ad-libitum and the birds had free access to clean drinking water all the time. All experiments measured the effects of QPM on broiler performances at the starter and finisher growth stages. In most cases, no effects were found at the starter stages. In order to provide a straightforward review of different experiments, the results presented and discussed herein refer to the finisher stage, except for analysis of financial effects where the starter phase was included.
As already mentioned, QPM can be cultivated for improving other nutrients as well as lysine/tryptophan (higher contents of other EAA, minerals, provitamin A and E, and anti-oxidative capacity). However, QPM hybrids used in the analyzed experiments were only high lysine, except for APQH9 used by Prakash et al. (2023), which was also a provitamine-A enriched QPM hybrid. The increased content of some other EAA found in several QPM hybrids can be considered as unintended compositional changes.
Along with broiler performance and carcass characteristics, certain effects of QPM use in broiler diets were analyzed in the papers presented. They include possible health benefits in broiler humoral immune response, serum cholesterol and liver enzymes, together with their effects on viscera macro-morphometry, organoleptic values of the meat and anti-oxidant and nutrient retention. These analyses were sporadic and at this point, without more profound studies, do not merit discussion. Thus, they were excluded from this review.
Lysine content of QPM hybrids used in broiler diets
Quality protein maize is defined by lysine content over 4 % of total protein and 0.35 % in a sample (Twumasi-Afriyie et al., 2016). Lysine and tryptophan contents are highly correlated (< 0.90), meaning that tryptophan content is also defined for QPM, in which it should be higher than 0.8 % of total protein and 0.075 % in a sample. Considering SM, these values are below 3.5 % in protein and 0.32 % in sample for lysine, as well as below 0.50 % and 0.065 %, respectively, for tryptophan.
Lysine content in SM and QPM used in the diets, as well as the difference (%) between them, is presented in Table 1. As expected, the Lysine content of all SM hybrids was in accordance with the criteria set by Twumasi-Afriyie et al. (2016). However, this is not the case for certain QPM hybrids, namely, QPM200 and Q300 (Khan et al., 2020) and the QPM hybrid used by Tiwari et al. (2013), which did not meet the QPM set values for lysine content, although it was higher compared to SM. Nevertheless, high quality protein maize (HQPM) hybrid HQPM-1 with high lysine content did not show significant positive effects as measured by one or more analyzed parameters (Rajasekhar et al., 2020). On the contrary, hybrids with low lysine content showed significant positive effects on BWG (QPM200 and QPM300) and FCR (QPM300) (Khan et al., 2020). Possible reasons for discrepancies between lysine content and the effects of QPM on broiler performance and carcass characteristics will be discussed below.
Lysine content (where provided) in standard maize (SM) and quality protein maize (QPM) hybrids used in broiler diets.
Broiler performance - BWG and FCR
The results of the effects of QPM on BWG and FCR are illustrated in Table 2. It shows an improvement in BWG (from 1.82 to 29.60 %) and FCR (from 1.14 to 15.66 %) in all experiments, except in De Groote et al. (2010), who detected no change.
Improvement of performance and carcass characteristics in broilers fed with quality protein maize (QPM) diets.
However, not all improvements were statistically of note. Significant changes were obtained in eight experiments (Table 2). Furthermore, no direct correlation between lysine content and BWG and FCR could be detected. Three main outcomes were observed. Firstly, a significant increase in these two traits was obtained with QPM hybrids with high lysine content, also higher by over 50 % compared to SM hybrids (Panda et al., 2010, 2014; Mushipe et al., 2017). Secondly, similarly higher lysine content in QPM hybrids has significantly affected either BWG or FCR in other studies (Rajasekhar et al., 2020; Prakash et al., 2023). Thirdly, although lysine content in the QPM hybrids was, in certain cases, low and close to that of SM, a significant increase was obtained for the performance parameters (Khan et al., 2020). Furthermore, in three experiments, significant effects were found for only one parameter - FCR with Abontem (Nartey et al., 2018) and HQPM-1 (Elangovan et al., 2022) hybrids, and BWG with QPM200 (Khan et al., 2020). Similarly, in the project conducted by the Maize Research Institute Zemun Polje in 2020/2021 (Ignjatović-Micić et al., 2020), QPM diets significantly improved FCR (by 11 %); however, no effect was found on BWG (Kostadinović et al., 2022), even though the lysine content of the QPM hybrid used was 0.44 %.
Additionally, in five papers in which the lysine content was not provided, significant changes were found for both (Onimisi et al., 2009; Nartey et al., 2018) or just one of the performance parameters - BWG (Almajiri et al., 2023; Jha et al., 2013) and FCR (Nartey et al., 2018; Amonelo and Roxas, 2008). No significant changes were found by Azmal et al. (2007) and De Groote et al. (2010). In addition to the papers presented in Table 2, similar results were obtained in other research studies (which were available in the form of abstracts). For example, significantly improved BWG and/or FCR were found in Osei et al. (1998) and Eshetie et al. (2011), while no significant changes were found in Tyagi et al. (2008). It is hard to pinpoint the exact reasons for the discrepancies found for QPM effects on the performance parameters in different experiments. However, though it could be assumed that amino acid profiles of QPM hybrids could have had a strong impact (discussed further). Lysine content, the difference between the SM and QPM, and the levels of other EAA can have consequential effects on BWG and FCR.
Carcass characteristics - BMY and AF
Breast meat yield and abdominal fat were evaluated in eight and five papers, respectively (Table 2). Significantly higher BMY and lower AF were found in four experiments. In the study by Nartey et al. (2018), a significant positive effect on BMY was found for the Etubi hybrid, but not for the Abontem hybrid. Insignificant increases in BMY were also detected by Onimisi et al. (2009).
In a meta-analysis of 21 published studies in which the effects of lysine on broiler performance and carcass characteristics were analyzed (Mendes et al., 2014), the authors concluded that high dietary lysine levels promoted greater BMY and reduced AF. This is in accordance with the results presented in Table 2, considering that statistically higher BMY and lower AF were obtained in the experiments in which lysine levels in QPM compared to SM hybrids were higher between 50 % (Prakash et al., 2023) and 63.63 % (Rajasekhar et al., 2020). Considering all the experiments, the increase of BMY was in the range of 2.4 % (Onimisi et al., 2009) to 31.6 % (Prakash et al., 2023), while the decrease in AF ranged from 7.76 % (Rajasekhar et al., 2020) to 62.3 % (Prakash et al., 2023).
Contrary to the improvements in BMY, Onimisi et al. (2009) reported no positive effects of QPM on BMY. Lysin content of SM and QPM was not provided, nor was an explanation. Contrary to all other research, Azmal et al. (2007) obtained a negative significant effect of QPM on BMY (decrease of 17.69 %). Additionally, even though AF decreased by 48 %, the change proved insignificant. The authors concluded that QPM had a negative or no effect on broiler improvement. At the same time they suggested that additional experiments are required to arrive at the correct and valid conclusion.
By the studies for BWG and FCR, discrepancies in the effects of QPM on BMY and AF improvement in broiler chickens found in the analyzed papers could be attributed to other EAA present in diets.
EAA profiles in QPM and their effects on broilers
Essential amino acids cannot be synthesized de novo or at a sufficient rate and must be supplemented through diets. The availability of amino acids is critical for optimal broiler chicken performance. Four amino acids, each having a different function, are considered critical: methionine, lysine, threonine, and tryptophan. The first limiting amino acid, methionine, is a precursor for cysteine, a dietary sulfur source, and an integral portion of body protein (Ojano-Dirain and Waldroup, 2002). Lysine is the second limiting amino acid, crucial to the protein synthesis for the growth of tissues, and the main essential amino acid required for broiler muscle building, which can increase meat yield (Tesseraud et al., 2001). The amount of lysine ingested daily directly influences on animal growth performance, as lysine is used mainly for body protein deposition. Threonine, the third limiting essential amino acid, plays a vital role in the synthesis of gut mucosal proteins, which also has better effects on growth performance, biochemical indexes, antioxidant function, and gut morphology, as well as acting as a nutrient immune modulator that affects the intestinal barrier function of broilers (Ji et al., 2019). Deficiency in tryptophan, the fourth essential amino acid, affects the utilization of dietary lysine and threonine and, consequently, animal growth. Tryptophan plays a role in protein anabolism and is indirectly related to its metabolites such as serotonin and melatonin. Thus, tryptophan could affect the secretion of hormones, development of immune organs, and meat production and quality (Fouad et al., 2021).
Essential amino acid profiles of SM and QPM were provided in five reviewed papers. The difference in the content of the seven most significant EAA for broiler performance and carcass characteristics between SM and QPM is presented in Figure 1A-F, with methionine missing in Panda et al. (2014) and tryptophan and arginine in Rajasekhar et al. (2020). Apart from tryptophan (similar) and leucine (lower), although the level of lysine in QPM200 and QPM300 was not significantly higher compared to SM (Table 1), the levels of other EAA were distinctly higher in Khan et al. (2020). The most prominent contrast was revealed in threonine, followed by methionine and arginine/histidine, with the first two being the limiting amino acids for growth performance. In QPM200, methionine was 1.6 times higher (0.12:0.20) and threonine 2.5 times (0.17:0.43). Similarly, in QPM300, methionine was two times higher (0.12:0.24) and threonine four times (0.17:0.69). Higher content of threonine and some other amino acids in QPM hybrids (arginine, histidine) as well as lower content of leucine which can interfere with protein synthesis, was also detected in Panda et al. (2010), Panda et al. (2014), Rajasekhar et al. (2020) and Elangovan et al. (2022), though they were not as prominent as in Khan et al. (2020). Although high lysine and other EAA contents were detected in Rajasekhar et al. (2020), the increase in BWG and FCR was insignificant. It can be assumed that other nutritional components in QPM were responsible since, in addition to the protein quality and EAA profiles, nutritional value of maize for poultry also depends on starch and oil content, as well as the presence of anti-nutrients (Cowieson, 2005). In order to clarify all the discrepancies found, a study on relevant metabolic pathways should be undertaken.
Essential amino acids content of standard maize and quality protein maize hybrids used in broiler diets in different experiments: A) Panda et al. (2010); B) Panda et al. (2014); C) Khan et al. (2020) = QPM200; D) Khan et al. (2020) = QPM300; E) Rajasekhar et al. (2020); and F) Elangovan et al. (2022). EAA = essential amino acid; Lys = lysine; Try = tryptophan; Tre = threonine; Met = methionine; Arg = arginine; His = histidine; Leu = leucine; SM = standard maize; QPM = quality protein maize.
It has been reported that lysine can increase carcass yields and improve its quality by reducing fat (Leclercq, 1998). Lysine also regulates body fat deposition through the inhibition of lipogenesis (Fouad and El-Senousey, 2014). As already stated for BWG and FCR, the levels of other EAA can have consequential effects on BMY and AF. For example, threonine is considered the second limiting amino acid for BMY (Estalkhzir et al., 2013), while methionine and arginine participate in lipid metabolism and fat deposition (Fouad and El-Senousey, 2014). In comparison to SM, amino acids profiles of QPM hybrids presented in the papers in which BMY and AF were improved (Panda et al., 2010, 2014; Rajasekhar et al., 2020), showed higher contents of several EAA, including threonine (0.31:0.38, 0.29:0.36 and 0.24:0.32, respectively) and arginine (0.40:0,66, 0.39:0.63, respectively), as well as a lower content of leucine (1.09:0.92, 1.04:0.87 and 1.09:0.94, respectively).
The data presented indicate the need for a more detailed chemical composition analysis if consequential conclusions on QPM effects on broiler performance and carcass characteristics are to be drawn.
Financial effects on broiler production and feed industry
Feed is the most significant input in broiler chicken production, accounting for 65-75 % of total production costs, with the protein component (e.g. soybean or fish meal) being the most expensive. QPM can potentially to be the source of protein and EAA lysine and tryptophan, thereby decreasing the percentage of protein component in diets and the need for synthetic lysine and tryptophan supplementation. However, according to the literature, the definitive conclusion on QPM cost-effectiveness in broiler production needs further consideration. Several economic analyses of QPM use in broiler diets are discussed below.
Amonelo and Roxas (2008) calculated income over feed and chick costs (IOFCC) based on the returns from the sales of broilers, cost of chicks, and feed consumed, using the formula IOFCC = [average live weight × % livability × price/kg] – [(feed consumed × cost of feeds) + cost of chick]. The effects of the three diets containing SM, SM supplemented with L-lysine (SM + L-Lys), and QPM, respectively, were compared. The percentage of synthetic lysine was 0.17 % in the starter and 0.08 % in the finisher SM + L-Lys diets. Furthermore, soybean and fish meals were used in different quantities as protein sources. Soybean meal was reduced to 9.1 % in starter and 3 % in finisher SM + L-Lys diets, while its reduction in QPM diets was to 9.8 and 5.5 %, respectively. The percentage of fish meal in all three starter diets was the same, while in SM + L-Lys finisher diet it was reduced to 34 % and in QPM finisher diet to 29.7 %. Financial analysis showed that IOFCC tended to increase in broilers fed with QPM-based diet (US$ 0.83 for QPM; US$ 0.69 for SM; US$ 0.50 for SM + L-Lys), surmising that the price of QPM was similar to that of SM. Higher IOFCC was attributed to the increased performance of broilers, especially in terms of feed efficiency, and partly due to the decreased use of soybean meal, fish meal and synthetic lysine additives.
In another study, gross expenditure was calculated by adding the cost of chicks, feeds, litter, labor, vaccines, medicines, and miscellaneous. In contrast, selling birds and litter obtained gross income (Jha et al., 2013). Birds were fed with four different diets - of SM, SM with synthetic lysine and methionine (SM + L-Lys + DL-Met), QPM or QPM with synthetic lysine and methionine (QPM + L-Lys + DL-Met). The percentage of L-Lys was 0.10 % in SM + L-Lys + DL-Met and QPM + L-Lys + DL-Met starter and finisher diets (DL-Met was presented in the same percentage). All four diets had the same ratio of soybean meal - 33.30 % in starter and 28.30 % in finisher diets. The highest overall income was observed from the group fed QPM with synthetic lysine and methionine, which also had the highest gross expenditure as well as the highest gross income. However, no statistical difference was found for net income per bird (US$ 0.49:0.51:0.53) and percentage of income over expenditure (33.56:35.25:36.31 %) between SM + L-Lys + DL-Met, QPM and QPM + L-Lys + DL-Met, respectively. Net income of US$ 0.37 and percentage of income over expenditure of 26.2 % of SM diet was statistically different from that of the other three diets.
Similarly, Khan et al. (2020) studied total cost, gross return (calculated on per kg live weight according to the market rate) and net-profit of using QPM based diets in an experiment in which the effects of two QPM hybrids (QPM200 and QPM300) were compared to SM. In this experiment, L-Lys was added to all diets, but it was reduced to 10 % in starter and finisher QPM based diets. In the same diets, soybean meal was reduced to 14.7 % (starter) and 34.7 % (finisher). All three financial parameters were in favor of QPM over SM. It was shown that birds raised on the QPM300 diet had the highest and those raised on the SM diet the lowest profit. Overall, the QPM300 diet had 14.2 % more profit than the SM-based diet.
Similar indications of positive financial effects of using QPM in broiler diets were observed in other research studies. The use of QPM reduces the cost of broiler production in Kenya by approximately 5 % for feed (De Groote et al., 2010). At the time of this research study, the value of broiler production in Kenya was estimated at about US$ 6 million per year, and the authors suggested that the feed manufacturers could save US$ 300,000 annually from the poultry feed produced using QPM, assuming that the cost reductions were not passed on in the form of reduced prices. Similarly, 5.5 % savings was found in the most recent cost benefit analysis of using QPM to replace dietary SM in broiler chicken diets in Nigeria (Almajiri et al., 2023). Although both feed cost per kg and total feed cost per bird was higher in QPM-based diets (US$ 0.22-0.24 and US$ 0.82-0.88, respectively) than the control (US$ 0.21 and US$ 0.81, respectively), feed cost per kg gain was lower (US$ 0.48-0.50) in diets containing 50 % and above QPM as a replacement for normal maize compared to the control (US$ 0.51). This was due to lower total feed intake and higher total weight gain obtained in birds fed these diets. These results implied that although QPM could completely replace SM in broiler diets, the most economical replacement level of 50 % can be recommended to poultry farmers and feed millers.
However, more comprehensive studies must be conducted on the cost-effectiveness of substituting SM with QPM in broiler diets. Such a study on the potential economic impact of bio-fortified maize in the Indian poultry sector was carried out by Krishna et al., 2014, including a survey of 75 independent broiler firms. The data collected referred to general aspects of management structure, poultry feed composition, purchasing price of feed ingredients, feed sources and output marketing. Additionally, the market price of ingredients from the firm survey, as well as the recommended minimum and maximum levels of feed components in the Indian poultry production sector were used to estimate the most economic feed composition. The results showed that the financial potential of QPM as poultry feed component appeared limited and that the economic benefits of QPM varieties would be marginal if the quality impacts on the end product (poultry meat) are not accounted for. The authors underlined the necessity for well-developed maize-poultry value chains for the successful diffusion of the QPM maize varieties, including the capacity to realize premiums sufficient to cover increased costs, contract prices flexible with general market trends, fair and effective distribution of benefits throughout the supply chain, traceability, and managing risks of climatically induced quality losses, etc.
Another recent profound study assessed the cost-reducing effects of using QPM and market structure in the poultry feed industry in Nepal, by surveying actors in the feed industry and maize value chain (Thapa et al., 2021). The results indicated that a ton of feed produced using QPM instead of SM reduced feed costs by at least US$ 7.10 for broilers. The authors assumed that all participants within the maize-poultry value chain would benefit from QPM. For example, 20 % of the poultry feed industry's cost savings would be passed on to the farmers and cooperatives who supply QPM grain, while traders would receive 5 % of the total cost savings per kg of QPM sold to the industry. However, similar to Krishna et al. (2014), a strong link and cooperation between the poultry feed sector and maize value chain actors is imperative for the financial potential of QPM to be fully exploited.
It is obvious that QPM has financial potential although it is currently exploited only to a limited extent. There is evidence that QPM is cost-effective compared to SM, mostly due to the mitigated use of synthetic amino acids and protein meals as well as to improved weight gain and feed conversion ratio. However, it is not clear if QPM can completely eliminate lysine supplementation due to different maize/lysine combination comparisons. On the other hand, comprehensive financial analyses highlighted that economic benefits would still be minor without significant impact on meat quality. Even if this requirement was achieved, a strong link between maize-poultry value chain is yet to be developed. To summarize, further in-depth experiments and well-established cooperation between different actors are necessary if the QPM potential is to be fulfilled.
Final remarks
Quality protein maize, as a maize hybrid with desirable value-added traits, has been recognized as the feed component which could contribute to the advancement of animal production. It is assumed that QPM has a high capacity for improving traits of major importance for both broiler producers (BWG and FCR) and consumers (BMY and AF). However, the results presented on the effects of different QPM hybrids on broiler performance and carcass characteristics do not support this assumption unconditionally - certain hybrids displayed significant effects, while others had positive but insignificant effects. Moreover, it was shown that the lysine content of QPM, which can differ significantly between the hybrids, is not the only EAA to positively impact the parameters analyzed. The results indicate that each QPM hybrid must be evaluated for all EAA and other relevant nutrients that affect a given trait before concluding about its benefits.
It was shown that the financial gain of using QPM in broiler diets can be achieved through reduced costs (decreasing the use of synthetic lysine and protein meals) for feed and broiler producers. Furthermore, seed companies could profit by launching new value-added products. However, to benefit sustainably from using QPM, a strong linkage between the feed industry and maize value chain actors is required.
In summary, the next steps in evaluating the effects of QPM should include: 1) careful choice of QPM hybrids to be implemented in broiler diets in terms of detailed analysis of chemical composition relevant to broiler performance and carcass characteristics; 2) experiments which would encompass as many traits of importance for livestock feed producers, broiler producers, and consumers as possible; and 3) intensive cooperation between researchers and industry. In this way, the best QPM hybrids would provide immutable benefits for all interested parties.
Acknowledgments
This work was supported by the Ministry of Science, Technological Development and Innovation of the Republic of Serbia under grant n° 451-03-66/2024-03/200040.
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Edited by
-
Edited by:
Francesco Montemurro
Publication Dates
-
Publication in this collection
29 Nov 2024 -
Date of issue
2025
History
-
Received
09 Feb 2024 -
Accepted
06 June 2024
