The ideal essential amino acid ratio for maintenance, growth and production of poultry

Author(s)

Juliano Cesar de Paula Dorigam

• Document type: Doctoral Thesis
• Press: Jaboticabal. 2016-04-07.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2016-02-26
• Advisor: Nilva Kazue Sakomura; Edney Pereira da Silva

Abstract

The traditional dose-response method used to determine the ideal essential amino acid ratio (IAAR) has been considered too costly, especially when breeders are used, because an assay for each essential amino acid (EAA) is necessary. On the other hand, the deletion method has been considered a quick and practical way to determine the IAAR, because only one assay is required. Thus, the aim of this thesis was to determine the optimal ratio of essential amino acids for breeders (broiler breeder hens and roosters) and broilers using the deletion method. The first study aimed to estimate the essential amino acid profile and the ideal ratio for maintenance of poultry by deletion method. A nitrogen (N) balance trial was conducted using 198 adult roosters, housed individually in metabolic cages. The treatments were 33 purified diets being 11 diets with an EAA mixture providing high protein intake of 500 mg N/BWkg0.75 per day, 11 diets providing medium protein intake of 250 mg N/BWkg0.75 per day (in each diet one EAA tested was reduced 50%) and 11 diets providing low protein intake of 125 mg N/BWkg0.75 per day (made by omitting the EAA tested). Each treatment had six replicates. After 48 h of fasting receiving water plus sucrose, the roosters were fed 40 g of the diets by tube once a day for three days. The excreta were collected within 72 h after the first feeding. The diets and excreta were analyzed for nitrogen content. For each EAA studied, a linear regression was fitted by N balance and EAA intake. The maintenance requirements were estimated as the EAA intake to maintain the N balance equal to zero. The daily EAA requirements for maintenance were estimated to be: Lys 11, Met 29, Thr 23, Trp 5, Arg 50, Val 29, His 6, Gly 54, Phe 49, Leu 78 and Ile 21 mg/BWkg0.75 per day. Therefore, the EAA ratio for maintenance was concluded to be Lys 100, Met 276, Thr 220, Trp 48, Arg 467, Val 275, His 60, Gly 511, Phe 467, Leu 735 and Ile 198% independent of the scale. The EAA profile and the ideal ratio for maintenance of poultry estimated in this study contribute to improve factorial model for estimating EAA requirements for poultry. In the second study, two approaches using amino acid deletion method, one with comparative slaughter and another with N balance, were used to re-evaluate the actual assumptions of ideal ratios between the EAA: lysine (Lys), methionine+cystine (Met+Cys), threonine (Thr), tryptophan (Trp), arginine (Arg), valine (Val), isoleucine (Ile), leucine (Leu), phenylalanine+tyrosine (Phe+Tyr), glycine+serine (Gly+Ser), and histidine (His) for growing broilers of Cobb 500 genotype during three periods (I: 6 to 21, II: 22 to 37, and III: 38 to 53 d). Per trial, 120 male chickens were housed in metabolic cages for assessment of individual N-balance and AA efficiency data. An AA balanced diet (BD) was formulated according to recommendations of Brazilian tables (Rostagno et al., 2011) for the ideal protein in growing broilers. The diets with different limiting AAs were created by dilution of BD with corn starch to achieve 0.70 of the AA level in BD and supplemented with crystalline AAs, except the AA under study. The AA diluted diets led to significant impairment of protein utilization and indicated valid limiting position of these AAs. Also, at start and the end of the trial a group of birds with mean body weight of each replicate was killed with no blood loss to determine nitrogen deposition by comparative slaughter technique. The mean value of the optimum ratios of the eleven tested EAAs determined by comparative slaughter in the three periods are: Lys100, Met+Cys 65, Thr 66, Trp 17, Arg 108, Val 79, Ile 61, Leu 122, Phe+Tyr 128, Gly+Ser 155, and His 41. Based on observed AA efficiency data, the optimum ratios determined by nitrogen balance are: Lys 100, Met+Cys 72, Thr 65, Trp 17, Arg 106, Val 76, Ile 67, Leu 107, Phe+Tyr 115, Gly+Ser 137, and His 35. There are some differences among the results obtained by the two methods (Louvain and Goettingen approach), but the Goettingen approach provided result in accordance with the literature and less variation in the results. The third study aimed to determine the model parameters for maximum nitrogen retention (NRmaxT), nitrogen maintenance requirement (NMR) and the efficiency of lysine utilization (bc-1) to determine the lysine (Lys) requirements of broiler breeder hens. The N balance trials were performed in two periods (I: 31-35 wks and II: 46-50 wks). Seven treatments were used with eight replicates and one hen per cage; the treatments consisted of seven diets with protein levels ranging from 58.8 to 311.9 g/kg of feed, with Lys being limiting in the dietary protein (c = 3.91 g of Lys in 100 g of CP). For each period, the data of nitrogen intake (NI), nitrogen excretion (NEX), nitrogen in egg mass (NEM), nitrogen deposition (ND, ND=NI-NEX) and nitrogen retention (NR, NR=ND+NEM+NMR) were obtained in a balance trial of 25 days. The NMR was calculated by the exponential relationship between NEX and NI. The NRmaxT and b (slope related to protein quality) were estimated by the exponential fit between NR and NI. The bc-1 was obtained dividing b by c. Based on the likelihood ratio test for the model parameters, the obtained values were 255 mg/BWkg0.67 for NMR, 0.000117 for b and 1684 mg/BWkg0.67 (period I) and 1484 mg/BWkg0.67 (period II) for NRmaxT. The Lys intakes were estimated by the function Lys = (ln(NRmaxT)-ln(NRmaxT-NR)):(16×bc-1)), which resulted in the Lys intakes of 915 and 876 mg/d for breeder hens in the periods I and II, respectively. The current study concludes that the optimal Lys requirement is in range with literature data, but the recommendations can be adapted according to feed intake, aimed protein deposition and dietary AA efficiency. The fourth study aimed to apply the individual AA efficiency data (bc-1) for lysine (Lys), methionine+cystine (Met+Cys), threonine (Thr), tryptophan (Trp), arginine (Arg), valine (Val), isoleucine (Ile), leucine (Leu), phenylalanine+tyrosine (Phe+Tyr), glycine+serine (Gly+Ser) and histidine (His) to derive an ideal AA ratio (IAAR) for breeder hens. N-balance trials were performed from 31 to 35 wks and from 46 to 50 wks. Twelve treatments with eight replicates and one hen per cage were used. A balanced diet (BD) was formulated to meet the IAAR and the requirement of other nutrients for breeder hens. The limiting diets were formulated diluting BD with corn starch and refilled with crystalline AAs and other feed ingredients, except for the AA under study. In each period, the data of N-intake (NI), N-excretion (NEX), N in egg mass (NEM), N-deposition (ND, ND=NI-NEX) and N-retention (NR, NR=ND+NEM+NMR) were obtained in a balance trial of 25 days. The b values (protein quality) were estimated by b = (ln(NRmaxT)-ln(NRmaxT-NR)):(NI)), where NRmaxT is the potential for maximum nitrogen retention of breeder hens. The bc-1 values were obtained dividing b by the dietary AA concentration (c, g AA/16g N). The limiting position of each AA was confirmed and the bc-1 values were used to obtain an average IAAR: Lys (100), Met+Cys (83), Trp (24), Thr (81), Arg (114), Val (90), Ile (93), Leu (105), Phe+Tyr (109), Gly+Ser (95), and His (35). The IAAR was in the line with the recommendation from the literature, validating this alternative procedure for predicting dietary IAAR for broiler breeder hens. Finally, the aim of the fifith study was to apply the deletion method to derive an IAAR for broiler breeder hens. The nitrogen balance trials were performed from 31 to 35 wks and from 46 to 50 wks. Twelve treatments with eight replicates and one hen per cage were used. A balanced diet (BD) was formulated to strictly meet the IAAR and the requirement of other nutrients. The limiting diets were formulated diluting BD with corn starch and refilled with crystalline amino acids (AA) and other feed ingredients, except for the AA under study. Each feeding trial lasted 25 days. The feather losses, egg production and egg weight were recorded daily and the samples were stored to further determine NEM and nitrogen in feather losses (NDFL), respectively. At the start and the end of each period, a group of breeder hens were slaughtered to further determine nitrogen deposition in the body (NDB) and feathers (NDF). The NR was calculated as the sum of NDB, NDF, NDFL, NEM, and the nitrogen maintenance requirement (NMR=255 mg/BWkg0.67 per day). The percent reduction in NR resulting from the individual AA deletions relative to BD and the percent of the AA to delete from the BD were used to calculate the optimum in-feed AA requirement. The average IAAR determined was: Lys (100), Met+Cys (86), Trp (23), Thr (80), Arg (113), Val (90), Ile (91), Leu (133), Phe+Tyr (108), Gly+Ser (94), and His (35). The IAAR determined in this study corroborate with the recommendations for broilers in the literature, particularly when using the Goettingen approach, validating the deletion method for determining the IAAR. In addition, the method has been standardized for broiler breeder hens and the results of this study allowed updating the ideal ratio for these birds. Likewise, the deletion method for determining the IAAR for maintenance was also standardized and the ideal profile updated. Finally, the standardization of these methods will allow Brazilian research enjoy a rapid and low-cost procedure to estimate and evaluate the IAARs. (AU)

• FAPESP's process: 13/07136-5 - Estimation of ideal essential amino acid ratio for poultry by deletion method
• Grantee: Juliano César de Paula Dorigam
• Support Opportunities: Scholarships in Brazil - Doctorate