Currently, exogenous enzymes are commonly used in poultry diets, especially to enhance growth performance, contribute to environmentally friendly production and increase economic feasibility (Aftab and Bedford 2018Aftab, U. & Bedford, M. R. 2018. The use of NSP enzymes in poultry nutrition: myths and realities. World's Poultry Science Journal, 74(2): 277-286. ISSN: 1743-4777. https://doi.org/10.1017/S0043933918000272). Also, exogenous enzymes have been used individually or in combination with various natural alternatives to eliminate and/or restrict the use of antibiotic growth promoters in poultry (Cowieson and Kluenter 2019Cowieson, A.J. & Kluenter, A.M. 2019. Contribution of exogenous enzymes to potentiate the removal of antibiotic growth promoters in poultry production. Animal Feed Science and Technology, 250: 81-92, ISSN: 3778-8401. https://doi.org/10.1016/j.anifeedsci.2018.04.026).
Lipases are enzymes with functional properties applied to animal production and in various fields: agrochemistry, medicine, pharmaceutical and food industry (Cavalcante et al. 2021Cavalcante, F.T.T., Neto, F.S., de Aguiar Falcão, I.R., da Silva Souza, J.E., de Moura Junior, L.S., da Silva Sousa, P. & dos Santos, J.C. 2021. Opportunities for improving biodiesel production via lipase catalysis. Fuel, 288: 119577, ISSN: 0016-2361. https://doi.org/10.1016/j.fuel.2020.119577). Lipases also participate in the hydrolysis of triglycerides into fatty acids and glycerol, which is important for controlling blood lipid levels (Olivecrona 2016Olivecrona, G. 2016. Role of lipoprotein lipase in lipid metabolism. Current Opinion in Lipidology, 27(3): 233-241, ISSN: 1473-6535. https://doi.org/10.3390/biomedicines9070782). Specifically, in poultry, lipid assimilation occurs at the lipid-water interface because this biomolecule (lipids) is insoluble in aqueous medium, contrary to digestive enzymes (Gole et al. 2022Gole, M., Manwar, S., Khose, K., Rathod, P., Kumar, D. & Ganguly, R.K.B. (2022) Efficacy evaluation of a poultry feed emulsifier in broiler chicken. The Pharma Innovation Journal, 11(1): 1119-1123, ISSN: 2349-8242. URL: https://www.thepharmajournal.com/archives/2022/vol11issue1S/PartQ/S-11-1-189-199.pdf). Upadhaya et al. (2019)Upadhaya, S.D., Yun, K.S., Zhao, P.Y., Lee, I.S. & Kim, I.H. 2019. Emulsifier as a feed additive in poultry and pigs-a review. Animal Nutrition and Feed Technology, 19(2): 323-336, ISSN: 0972-2963. https://doi.org/10.5958/0974-181X.2019.00030.1 reported that birds in the first days of life produce low concentrations of pancreatic lipase, which can provoke poor digestibility of lipids (mainly saturated fatty acids) and also affect feed efficiency.
Castro and Kim et al. (2021)Castro, F.L. & Kim, W.K. 2021. Exogenous lipase supplementation to low-energy, low-protein, and low–amino acid diets for broiler chickens from one to 42 d. Journal of Applied Poultry Research, 30(1):100–117, ISSN: 1537-0437. https://doi.org/10.1016/j.japr.2020.100117 reported positive results when they used a dietary lipase in the early life stages of broilers. However, Movagharnejad et al. (2020)Movagharnejad, M., Kazemi-Fard, M., Rezaei, M. & Teimuri-Yansari, A. 2020. Effects of lysophospholipid and lipase enzyme supplementation to low metabolizable energy diets on growth performance, intestinal morphology and microbial population and some blood metabolites in broiler chickens. Brazilian Journal of Poultry Science, 22(2): 1-8, ISSN: 1806-9061. https://doi.org/10.1590/1806-9061-2019-1118 did not find improvements in growth performance of chickens when they used a lipase enzyme combined with lysophospholipids in the diets. Few studies have focused on the use of lipase enzymes in low-calorie diets in slow-growing birds such as laying pullets, especially to reduce the use of energy corrector, reduce production costs, maintain and improve the feed efficiency of this poultry category, which affects the productivity of the future laying hen. The objective of the present study was to evaluate the effect of a lipase enzyme (Lipase AN6) on the bioproductive indicators of laying pullets.
Materials and methods
⌅Experimental location
⌅The experiment was developed at the Poultry Research and Teaching Center of the Pan-American Agricultural School, Zamorano, located 32 km between Tegucigalpa-Danlí, Honduras. The average annual temperature is 26 °C, with average precipitation of 1100 mm and altitude of 800 m a.s.l.
Animals, experimental design and treatments
⌅A total of 700 Dekalb White® laying pullets, one day old and sexed, were placed for 17 weeks according to a completely randomized design with two treatments and seven repetitions per treatment. The treatments consisted of basal diets (T1), formulated with corn and soymeal, and the inclusion of 0.01 % lipase in hypocaloric diets (T2) (-0.42 MJ/kg). The lipase enzyme (Lipase AN6) was purchased from company “Enzimas y Productos Químicos S.A. (Enziquim)”, Mexico. Also, the company's recommendation for the inclusion level and energy release (0.42 MJ /kg) of the enzyme was considered.
Five experimental periods were used: 1-3 weeks, 4-6 weeks, 7-10 weeks, 11-15 weeks and 16-17 weeks. The diets were prepared in the feed factory of the Poultry Research and Teaching Center, University of Zamorano. The requirements described in the manual of the genetic line used (Hendrix-Genetics 2020Hendrix-Genetics. 2020. Nutrition Guide. Available at: https://layinghens.hendrix-genetics.com/documents/883/Nutrition_Guide_English_vs4.pdf. Consulted: June 17/2023) were considered. Table 1 shows the ingredients and nutritional contributions of the experimental diets.
Ingredients, % | 1-3 weeks | 4-6 weeks | 7-10 weeks | 11-15 weeks | 16-17 weeks | |||||
---|---|---|---|---|---|---|---|---|---|---|
T1 | T2 | T1 | T2 | T1 | T2 | T1 | T2 | T1 | T2 | |
Cornmeal | 55.745 | 58.255 | 60.64 | 61.28 | 55.82 | 58.22 | 53.95 | 56.42 | 54.71 | 57.13 |
Soymeal | 34.11 | 33.74 | 29.92 | 29.37 | 26.90 | 26.62 | 21.86 | 21.56 | 26.37 | 26.07 |
Premix1 | 0.50 | 0.50 | 0.35 | 0.35 | 0.35 | 0.35 | 0.35 | 0.35 | 0.35 | 0.35 |
Common salt | 0.28 | 0.28 | 0.23 | 0.23 | 0.23 | 0.23 | 0.25 | 0.25 | 0.25 | 0.25 |
Sodium bicarbonate | 0.23 | 0.23 | 0.28 | 0.28 | 0.28 | 0.28 | 0.28 | 0.28 | 0.28 | 0.28 |
Palm oil | 3.82 | 1.68 | 1.60 | 0.00 | 4.71 | 2.6 | 4.98 | 2.84 | 6.08 | 3.95 |
Wheat bran | 2.00 | 2.00 | 3.00 | 4.50 | 8.00 | 8.00 | 15.00 | 15.00 | 4.00 | 4.00 |
Choline | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 |
DL-Methionine | 0.20 | 0.20 | 0.20 | 0.20 | 0.18 | 0.17 | 0.13 | 0.12 | 0.19 | 0.19 |
L-Threonine | 0.00 | 0.00 | 0.04 | 0.04 | 0.03 | 0.02 | 0.0 | 0.00 | 0.00 | 0.00 |
L-Lysine | 0.09 | 0.09 | 0.11 | 0.11 | 0.09 | 0.09 | 0.06 | 0.06 | 0.02 | 0.02 |
Calcium carbonate | 1.75 | 1.75 | 1.68 | 1.68 | 1.61 | 1.61 | 1.61 | 1.61 | 5.95 | 5.95 |
Monocalcium phosphate | 1.03 | 1.02 | 1.60 | 1.60 | 1.45 | 1.45 | 1.18 | 1.15 | 1.45 | 1.45 |
Mycotoxin sequestrant | 0.075 | 0.075 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 |
Exogenous enzymes2 | 0.07 | 0.07 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 |
Coccidiostat | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 |
Lipase enzyme | 0.00 | 0.01 | 0.00 | 0.01 | 0.00 | 0.01 | 0.00 | 0.01 | 0.00 | 0.01 |
Costs (USD/t) | 548.64 | 536.55 | 537.04 | 524.83 | 537.98 | 525.57 | 511.80 | 499.33 | 538.6 | 526.74 |
Contributions (%) | ||||||||||
Metabolizable energy (MJ/kg) | 12.34 | 11.92 | 11.92 | 11.51 | 12.34 | 11.92 | 12.13 | 11.72 | 12.34 | 11.92 |
Crude protein | 20 | 20 | 18.5 | 18.5 | 17.5 | 17.5 | 16.00 | 16.00 | 16.50 | 16.50 |
Ca | 1.05 | 1.05 | 1.00 | 1.00 | 0.95 | 0.95 | 0.90 | 0.90 | 2.50 | 2.50 |
Available P | 0.45 | 0.45 | 0.47 | 0.47 | 0.45 | 0.45 | 0.40 | 0.40 | 0.43 | 0.43 |
Lysine | 1.10 | 1.10 | 0.96 | 0.96 | 0.88 | 0.88 | 0.76 | 0.76 | 0.78 | 0.78 |
Methionine+Cystine | 0.80 | 0.80 | 0.72 | 0.72 | 0.67 | 0.67 | 0.59 | 0.59 | 0.66 | 0.66 |
Threonine | 0.70 | 0.70 | 0.65 | 0.65 | 0.60 | 0.60 | 0.52 | 0.52 | 0.55 | 0.55 |
Na | 0.18 | 0.18 | 0.17 | 0.17 | 0.17 | 0.17 | 0.18 | 0.18 | 0.18 | 0.18 |
Cl | 0.20 | 0.20 | 0.17 | 0.17 | 0.17 | 0.17 | 0.18 | 0.18 | 0.18 | 0.18 |
1Each kg contains: vit. A 10 x 106 I.U., D3 1.5x 106 I.U., K3 2100 mg, E 10000 mg, thiamine, 800 mg, riboflavin 2500 mg, pantothenic acid 10000 mg, pyridoxine 2500 mg, folic acid 250 mg, biotin 100 mg, vit. B12 15 mg, manganese 60000 mg, copper 8000 mg, iron 60000 mg, zinc 50000 mg, selenium 200 mg, iodine 800 mg, cobalt 500 mg, antioxidant 125000 mg.
2Lumis Lbzyme X50® multienzyme complex is composed by xylanase (25000 U/g), mannanase (250 IU/g), beta-glucanase (2500 IU/g), cellulase (400000 U/g), pectinase (80 IU/g), galactosidase (100 U/g), protease (2500 Hut/g), amylase (60000 U/g) and phytases (15000 FTU/g).
Experimental conditions
⌅Each repetition corresponded to a pen with dimensions of 5.92 m2 each (1.6 × 3.7 m), where 50 pullets/pen were located, at a rate of 10.13 pullets/m2. Feed and water were offered ad libitum in hopper feeders and dual automatic drinkers, respectively. Temperature and ventilation in the house were controlled by gas brooders, curtain management, and fans, respectively. The house was disinfected with quaternary ammonium (5 %) 24 h before the arrival of the batch of pullets. No medications or therapeutic veterinary care were administered throughout the experimental stage.
Productive indicators
⌅All bioproductive indicators were determined in periods 1-3 (starter 1), 4-6 (starter 2), 7-10 (grower), 11-15 (development) and 16-17 weeks (pre-lay). Viability was determined by the live animals among those existing at the beginning of the experiment. The initial and final weighing of each stage was carried out individually on a SARTORIUS model BL 1500 digital scale with precision ± 0.1 g. Cumulative feed intake was determined using the offer and rejection method. Feed conversion ratio was calculated as the amount of feed ingested for a gain of 1 g of body weight (BW). At week 17, uniformity was calculated according to the coefficient of variation (CV, %).
Statistical analysis
⌅A completely randomized design was used. The Student's t test was performed for two independent samples using the SPSS 1/23/2014 program (SPSS Inc., Chicago, IL, USA). Values of P<0.05 were taken to indicate significant differences. Viability was determined by comparison of proportions using the COMPRAPRO 1.0® program (Font et al. 2007Font, H., Noda, A., Torres, V., Herrera, M., Lizazo, D., Sarduy, L. & Rodríguez, L. 2007. COMPARPRO: Comparación de Proporciones, Versión: 1.0. Mayabeque, Cuba).
Results and discussion
⌅Table 2 shows the effect of the inclusion of an exogenous enzyme (lipase) on growth performance of laying pullets fed with low-calorie diets. In the initial stage (starter 1, 1-3 weeks), the diet with the inclusion of lipase did not affect body weight, feed intake, feed conversion ratio and viability. However, in the second stage (starter 2, 4-6 weeks), lipase improved body weight and reduced feed conversion ratio, without modifying feed intake and viability.
Items | Experimental treatments | SEM ± | P value | |
---|---|---|---|---|
T1 | T2 | |||
1-3 weeks | ||||
Initial body weight, g | 35.71 | 35.15 | 0.430 | 0.3741 |
Body weight, g | 189.50 | 187.62 | 1.953 | 0.5108 |
Feed intake, g | 396.00 | 394.86 | 1.063 | 0.4624 |
Feed conversion ratio | 2.58 | 2.59 | 0.028 | 0.7492 |
Viability, % | 98.00 | 97.71 | 0.841 | 0.8147 |
4-6 weeks | ||||
Body weight, g | 408.96 | 449.36 | 5.413 | 0.0010 |
Feed intake, g | 507.23 | 497.12 | 8.748 | 0.4292 |
Feed conversion ratio | 2.32 | 1.95 | 0.057 | 0.0010 |
Viability, % | 99.14 | 99.12 | 0.411 | 0.9764 |
7-10 weeks | ||||
Body weight, g | 684.24 | 687.95 | 5.388 | 0.6351 |
Feed intake, g | 892.05 | 914.56 | 18.060 | 0.3954 |
Feed conversion ratio | 3.24 | 3.73 | 0.093 | 0.0524 |
11-15 weeks | ||||
Body weight, g | 1064.60 | 1088.55 | 9.823 | 0.1105 |
Feed intake, g | 1561.39 | 1645.73 | 33.967 | 0.0154 |
Feed conversion ratio | 3.24 | 4.11 | 0.054 | 0.0010 |
Viability, % | 99.41 | 99.71 | 0.336 | 0.5367 |
16-17 weeks | ||||
Body weight, g | 1190.39 | 1199.19 | 8.099 | 0.4573 |
Feed intake, g | 685.39 | 652.91 | 19.455 | 0.2615 |
Feed conversion ratio | 5.52 | 5.95 | 0.288 | 0.3124 |
1-17 weeks | ||||
Body weight, g | 4042.06 | 4105.17 | 63.759 | 0.4974 |
Feed intake, g | 3.50 | 3.52 | 0.037 | 0.6238 |
Uniformity | 2.35 | 2.20 |
T1 control diet, T2 inclusion of 0.01 % of a lipase enzyme in hypocaloric diets (-0.42 MJ/kg).
In the grower (7-10 weeks) and pre-lay (16-17) stages, no productive indicator changed due to the effect of the experimental groups. However, in the development stage (11-15 weeks), the hypocaloric diet with lipase increased feed intake and feed conversion ratio; also, uniformity was similar between treatments, according to the coefficient of variation.
One of the aims of the experiment was to verify whether the lipase enzyme, which provides 0.42 MJ/kg of metabolizable energy (according to information from the company Enziquim), reduces the diet cost (table 1), without modifying the growth performance of laying pullets from birth to pre-lay (1-17 weeks), considering that young birds have low enzymatic activity (Temairaev et al. 2020Temiraev, V.H., Baeva, A.A., Vityuk, L.A., Mamukaev, M.N., Yurina, N.A., Ktsoeva, I.I. & Vologirova, F.A. 2020. Effect of probiotics on digestive metabolism in growing and laying poultry birds. Journal of Livestock Science, 11(1): 33-39, ISSN: 2277-6214. https://doi.org/10.33259/JLivestSci.2020.33-39). This is the case of endogenous lipase, which is produced in the pancreas and participates in lipid metabolism to catabolize the hydrolysis of triglycerides to glycerol and free fatty acids (Wickramasuriya et al. 2020Wickramasuriya, S.S., Macelline, S.P., Cho, H.M., Hong, J.S., Park, S.H. & Heo, J.M. 2020. Physiological effects of a tallow-incorporated diet supplemented with an emulsifier and microbial lipases on broiler chickens. Frontiers in Veterinary Science, 7: 583998. ISSN: 2297-1769. https://doi.org/10.3389/fvets.2020.583998).
Feed intake of pullets in weeks 1-3 (starter 1) remained unchanged despite the energy reduction (0.42 MJ/kg) in the diet when the lipase enzyme was included (table 2). According to Lamot et al. (2017)Lamot, D.M., Sapkota, D., Wijtten, P.J.A., van den Anker, I., Heetkamp, M.J.W., Kemp, B. & van den Brand, H. 2017. Diet density during the first week of life: Effects on energy and nitrogen balance characteristics of broiler chickens. Poultry Science, 96(7): 2294-2300, ISSN: 0032-5791. http://dx.doi.org/10.3382/ps/pex020 and Barzegar et al. (2020)Barzegar, S., Wu, S.B., Choct, M. & Swick, R.A. 2020. Factors affecting energy metabolism and evaluating net energy of poultry feed. Poultry Science, 99(1): 487-498, ISSN: 0032-5791. https://doi.org/10.3382/ps/pez554, the energy concentration in the diet has a direct influence on feed intake in birds, which demonstrates that the diets had a similar contribution of metabolizable energy (table 1). Bakare et al. (2021)Bakare, A.G., Zindove, T.J., Iji, P.A., Stamatopoulos, K. & Cowieson, A.J. 2021. A review of limitations to using cassava meal in poultry diets and the potential role of exogenous microbial enzymes. Tropical Animal Health and Production, 53(4): 1-13, ISSN: 1573-7438. https://doi.org/10.1007/s11250-021-02853-6 reported growing interest in using exogenous enzymes in poultry diets to improve nutrient utilization and decrease diet costs. Apparently, the use of lipase indicated higher availability of nutrients (lipids, fatty acids and glycerol), important to maximize enzymatic activity in young animals (Valentini et al. 2020Valentini, J., Da Silva, A.S., Fortuoso, B.F., Reis, J.H., Gebert, R.R., Griss, L.G. & Tavernari, F.C. 2020. Chemical composition, lipid peroxidation, and fatty acid profile in meat of broilers fed with glycerol monolaurate additive. Food Chemistry, 330: 127187, ISSN: 0308-8146. https://doi.org/10.1016/j.foodchem.2020.127187). Furthermore, oral administration of lipase reduced the diet cost (1-3 weeks) by 12.09 USD/t (table 1).
The use of the lipase enzyme in diets without the energy corrector (African palm oil) decreased the cost of the diets by 12.21 USD/t (table 1) and promoted body weight from weeks 4-6 (table 2). Zhu et al. (2014)Zhu, H.L., Hu, L.L., Hou, Y.Q., Zhang, J. & Ding, B.Y. 2014. The effects of enzyme supplementation on performance and digestive parameters of broilers fed corn-soybean diets. Poultry Science, 93(7): 1704-1712, ISSN: 1350-4177. https://doi.org/10.3382/ps.2013-03626 reported that the use of a lipase enzyme in hypocaloric diets improved the activity of pancreatic enzymes and pepsin, and also increased the height and surface area of the villi of the jejunum and ileum in poultry. This confirms that, in young birds, the use of lipase favors the digestion and absorption of lipids and directly affects the feeding efficiency of these slow-growing animals. Likewise, Siqueira et al. (2021)Siqueira, L.A., Almeida, L.F., Fernandes, J.P.A., Araújo, M.C.U. & Lima, R.A.C. 2021. Ultrasonic-assisted extraction and automated determination of catalase and lipase activities in bovine and poultry livers using a digital movie-based flow-batch analyzer. Ultrasonics Sonochemistry, 79: 105774, ISSN: 1350-4177. https://doi.org/10.1016/j.ultsonch.2021.105774 recommended the use of exogenous lipases in diets, because birds do not produce lingual and gastric lipase. It is in the gizzard and small intestine where lipid emulsification occurs. However, young birds have an immature digestive system, which causes low digestibility of lipids and less use of the metabolizable energy of the diet.
The experimental group with lipase caused better feeding efficiency of the birds in the initial phase 2 (table 2). Although there are still contradictions about the metabolizable energy requirements in the early stages of life in pullets, Savoldi et al. (2012)Savoldi, T.L., Nunes, R.V., Scherer, C., Tsutsumi, C.Y., Scheneiders, J.L., Marques, M.F.G. & Meza, S.K.L. 2012. Níveis de energia metabolizável e lisina digestível para o desempenho de pintos de corte de 1 a 10 dias de idade. Scientia Agraria Paranaensis, 11: 49-58, ISSN: 1983-1471. https://doi.org/10.18188/sap.v11io.7870 stated that diets with high levels of metabolizable energy during the initial phase favor weight gain and feed conversion ratio. Furthermore, Noy and Sklan (1995)Noy, Y. & Sklan, D. 1995. Digestion and absorption in the young chick. Poultry Science, 74(2): 366–373, ISSN: 0032-5791. https://doi.org/10.3382/ps.0740366 found that poultry have fat digestibility of 85 % in the first days after hatching, and only growth factor improves the digestibility of this biomolecule. Thus, the use of lipase enzymes could enhance the absorption of lipids in the early stages of life of birds. Upadhaya et al. (2019)Upadhaya, S.D., Yun, K.S., Zhao, P.Y., Lee, I.S. & Kim, I.H. 2019. Emulsifier as a feed additive in poultry and pigs-a review. Animal Nutrition and Feed Technology, 19(2): 323-336, ISSN: 0972-2963. https://doi.org/10.5958/0974-181X.2019.00030.1 reported in broilers that lipase supplementation improved pellet durability, endogenous enzyme production, and absorption of lipids and fat-soluble vitamins.
During the growth stage (7-10 weeks), productive indicators were similar in birds fed with the inclusion of 0.01 % lipase in hypocaloric diets (11.92 MJ/kg) and reduction of African palm oil (2.11 %) and of the cost of the diet at 12.41 USD/t (table 1). The results demonstrate that the dietary inclusion of exogenous lipase has a greater growth-promoting effect in the weeks prior (4-6 weeks) to the growth phase (7-10 weeks). de Oliveira et al. (2019)de Oliveira, L.S., Balbino, E.M., Silva, T.N.S., Ily, L., da Rocha, T.C., de Oliveira Strada, E.S. & de Brito, J.A.G. 2019. Use of emulsifier and lipase in feeds for broiler chickens. Semina: Ciências Agrárias, 40(6Supl2): 3181-3196, ISSN: 1679-0359. https://doi.org/10.5433/1679-0359.2019v40n6Supl2p3181 found that the use of a dietary lipase changed the feed consumption of birds, with greater effectiveness in the initial stages. Studies with lipase enzymes in fast-growing birds (chickens) are insufficient (Munir and Maqsood 2013Munir, K. & Maqsood, S. 2013. A review on role of exogenous enzyme supplementation in poultry production. Emirates Journal of Food and Agriculture, 25(1): 66-80, ISSN: 2079-0538. https://doi.org/10.9755/ejfa.v25i1.9138). Al-Marzooqi and Leeson (2000)Al-Marzooqi, W. & Leeson, S. 2000. Effect of dietary lipase enzyme on gut morphology, gastric motility, and long-term performance of broiler chicks. Poultry Science, 79(7): 956-960. ISSN: 1350-4177. https://doi.org/10.1093/ps/79.7.7.956 reported that increasing levels of a lipase enzyme did not change the growth performance and relative weight of internal organs during 42 d of age. Apparently, in slow-growing birds (such as pullets), the effect is more evident. However, other studies with this lipase enzyme are necessary to verify this hypothesis.
During the development phase (11-15 weeks), the pullets are fed with maintenance diets, low in metabolizable energy and crude protein and rich in fibrous compounds, the body weight of the experimental groups was similar to that reported by the manual of the genetic line (Hendrix-Genetic 2022Hendrix-Genetics. 2022. Management Guide. Available at: https://layinghens.hendrix-genetics.com/en/technical-support/management/. Consulted: June 17/2023). The diets cost with lipase decreased by 12.47 USD/t (table 1, 11-15 weeks). However, this experimental treatment increased feed intake and, therefore, feed conversion ratio (table 2). Nogueira et al. (2013)Nogueira, W.C.L., Velásquez, P.A.T., Furlan, R.L. & Macari, M. 2013. Effect of dietary energy and stocking density on the performance and sensible heat loss of broilers reared under tropical winter conditions. Brazilian Journal of Poultry Science, 15: 53-57, ISSN: 1806-9061. https://doi.org/10.1590/S1516-635X2013000100009 found that soy lecithin supplementation, alone or in combination with a lipase enzyme, decreased production efficiency due to increased feed conversion ratio of broilers. Other studies reported that dietary inclusion with 0.075 % lipase improved lipid absorption. However, feed intake and body weight gain in poultry decreased, due to the high concentration of the exogenous enzyme (lipase) and contamination with cholecystokinin (Al-Marzooqi and Leeson 1999Al-Marzooqi, W. & Leeson, S. 1999. Evaluation of dietary supplements of lipase, detergent, and crude porcine pancreas on fat utilization by young broiler chicks. Poultry Science, 78(11): 1561-1566. ISSN: 0032-5791. https://doi.org/10.1093/ps/78.11.1561). Apparently, the stimulation of voluntary consumption in this productive stage (development) is related to the fact that lipase has less energy release than in initial stages, thus birds consume more feed due to the energy deficit for organic functions. An opposite effect was reported by Wu et al. (2005)Wu, G., Bryant, M.M., Voitle, R.A. & Roland Sr, D.A. 2005. Effect of dietary energy on performance and egg composition of Bovans White and Dekalb White hens during phase I. Poultry Science, 84(10): 1610-1615, ISSN: 1350-4177. https://doi.org/10.1093/ps/84.10.1610, who report that diets with high energy concentration decrease the voluntary consumption of poultry in all productive stages.
In pre-laying (16-17 weeks), the energy requirement is directly related to body weight, ambient temperature, feathering and future egg production (Hadinia et al. 2018Hadinia, S.H., Carneiro, P.R.O., Ouellette, C.A. & Zuidhof, M.J. (2018) Energy partitioning by broiler breeder pullets in skip-a-day and precision feeding systems. Poultry Science, 97(12): 4279-4289, ISSN: 1350-4177. https://doi.org/10.3382/ps/pey283). The inclusion of lipase reduced the use of African palm oil by 2.14 % and the cost of diets by 11.86 USD/t (table 1). Apparently, the enzyme supplied the missing energy in the hypocaloric diet (-0.42 MJ/kg), since the productive performance was similar for both treatments. Although no studies were found on the effect of lipase enzymes in the pre-laying stage, Castro and Kim (2021)Castro, F.L. & Kim, W.K. 2021. Exogenous lipase supplementation to low-energy, low-protein, and low–amino acid diets for broiler chickens from one to 42 d. Journal of Applied Poultry Research, 30(1):100–117, ISSN: 1537-0437. https://doi.org/10.1016/j.japr.2020.100117 reported that the inclusion of a lipase enzyme in finishing diets (29-42 days) increased body weight gain and decreased the negative effects of diets with low nutrient concentrations in fast-growing birds.
Overall (1-17 weeks), the use of the lipase enzyme (Lipase AN6) maintained the bioproductive indicators of laying pullets fed with low-calorie diets and reduced the use of the energy corrector (African palm oil) between 0 to 2.14 % in the diet. Similar results were noted by Suresh et al. (2014)Suresh, B.N., Reddy, B.S.V., Prabhu, T.M., Manju, G.U. & Suma, N. 2014. Effect of dietary inclusion of lipid utilizing agents and NSP-degrading enzymes on performance of layers. Animal Nutrition and Feed Technology, 14(2): 379-384, ISSN: 0972-2963. https://doi.org/10.5958/0974-181X.2014.01330.4, who found no changes for feed intake and feed conversion ratio when they used treatments that included lipid emulsifying agents (0.2 g of lipase and 0.2 g/kg of soy lecithin). Furthermore, Lichovníková et al. (2002)Lichovnikova, M., Zeman, L., Klecker, D. & Fialova, M. 2002. The effects of the long-term feeding of dietary lipase on the performance of laying hens. Czech Journal of Animal Science, 47(4): 141-145, ISSN: 1805-9309. URL: https://agris.fao.org/agris-search/search.do?recordID=CZ2002000806 reported that the addition of lipase to hypocaloric diets kept productive indicators unchanged in 72-week-old laying hens. For their part, Meng et al. (2004)Meng, X., Slominski, B.A. & Guenter, W. 2004. The effect of fat type, carbohydrase, and lipase addition on growth performance and nutrient utilization of young broilers fed wheat-based diets. Poultry Science, 83(10): 1718-1727, ISSN: 1350-4177. https://doi.org/10.1093/ps/83.10.1718 noted that the productivity and nutrient digestibility of broilers was not affected by the dietary inclusion of exogenous enzymes (including lipase).
Uniformity is one of the most important indicators in the production of pullets, since it evaluates the homogeneity of the batch, which has a direct impact on the future layer (Asensio et al. 2020Asensio, X., Abdelli, N., Piedrafita, J., Soler, M.D. & Barroeta, A.C. 2020. Effect of fibrous diet and vitamin C inclusion on uniformity, carcass traits, skeletal strength, and behavior of broiler breeder pullets. Poultry Science, 99(5): 2633-2644, ISSN: 1350-4177. https://doi.org/10.1016/j.psj.2020.01.015). According to Delgado et al. (2020)Delgado, A., Valdivié, M. & Martínez, Y. 2020. Evaluación del raquis de maíz troceado como cama avícola sobre el desempeño productivo de pollitas ponedoras de reemplazo Dekalb White®. Revista de Producción Animal, 32(2): 14-26; ISSN: 2224-7920. http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S2224-79202020000200014#:~:text=Est%C3%A1%20investigaci%C3%B3n%20confirma%20que%20el,gen%C3%A9tica%20(Dekalb%2C%202014), a CV of 8 % corresponds to very uniform batches. These authors found that the CV increases with the age of the pullets. This demonstrates that both experimental groups had a uniform flock at week 17 of age (table 2) and that lipase did not modify this productive indicator. Sweeney et al. (2022)Sweeney, K.M., Aranibar, C.D., Kim, W.K., Williams, S.M., Avila, L.P., Starkey, J.D. & Wilson, J.L. 2022. Impact of every-day versus skip-a-day feeding of broiler breeder pullets during rearing on body weight uniformity and reproductive performance. Poultry Science, 101959, ISSN: 0032-5791. https://doi.org/10.1016/j.psj.2022.101959 reported that the growth of pullets with a similar body weight in the flock influences the age at first egg, laying persistence and egg weight uniformity of laying hens. In this study, regrouping was not necessary to homogenize the flock, which is a common practice in raising pullets and replacing breeders (García et al. 2019García, J., Mandalawi, H.A., Fondevila, G. & Mateos, G.G. (2019) Influence of beak trimming and inclusion of sodium butyrate in the diet on growth performance and digestive tract traits of brown-egg pullets differing in initial body weight. Poultry Science, 98(9): 3937-3949, ISSN 1350-4177. https://doi.org/10.3382/ps/pez129).
Conclusions
⌅Dietary inclusion with 0.01 % of Lipase AN6 with an energy contribution of 0.42 MJ/kg decreased the level of inclusion of the African palm oil and the cost of diets in all productive stages. Likewise, using this lipase enzyme did not affect the productivity and uniformity of Dekalb White® laying pullets (1-17 weeks)