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Bioavailability of methionine hydroxy analogue calcium salt compared to DL-methionine for broilers in growth phase

Fernando Andrés Prado Antayhua ; Nilva Kazue Sakomura ; Letícia Soares ; Juliano César de Paula Dorigam ; Warley Junior Alves ; Felipe de Lima Junqueira Franco Fabbri
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Methionine is the first limiting amino acid in poultry diets based on corn and soybean
meal. Different sources are available to balance these diets. Bioavailability is different for
each methionine source due to its rate of absorption and metabolic pathways. An
experiment was conducted to evaluate the bioavailability of methionine hydroxy analogue
calcium salt (MHA-Ca) in comparison to DL-Methionine (DL-Met). It was used 1890
male broilers (Cobb 500) with 21 days of age. The birds were distributed in a complete
randomized design with nine treatments, seven replicates with 30 birds each. The
treatments consisted of one basal diet (deficient and without supplementation of any
methionine source) with 0.544% of digestible methionine plus cystine (Met+Cys) and the
basal diets supplemented with MHA-Ca (0.063; 0.183; 0.302; 0.540% MHA-Ca) or DLMet
(0.054; 0.156; 0.259; 0.463% DL-Met) in replacement of the inert to obtain four
levels of Met+Cys(0.594; 0.694; 0.794 and 0.994% Met+Cys). For the analysis, 5% of
significance was considered in the adjustment of non-linear model using SAS. The
variables evaluated were body weight gain (BWG), feed conversion (FC), carcass yield
(CY), abdominal fat (AF) and breast yield (BY). Multi-exponential regression model was
used to determine bioavailability of MHA-Ca in relation to DL-Met supplementation for
each variable and was calculated by dividing the slope of MHA-Ca by the slope of DLMet.
Broilers fed diets supplemented with MHA-Ca and DL-Met improved BWG and FC
in relation to broilers fed basal diet. The models obtained were BWG = 1833.1 + 279.6 *
(1-e – (11.132 * DL-Met + 6.632 * MHA-Ca)), FC = 1.844 + 0.247 * (1-e – (9.878 * DL-Met + 6.452 * MHA-Ca)),
CY = 74.914 + 2.592 * (1-e – (8.218 * DL-Met + 3.976 * MHA-Ca)), AF = 2.246 + 0.573 * (1-e – (8.063
* DL-Met + 7.813* MHA-Ca)) and BY = 23.508 + 5.460 * (1-e – (5.546 * DL-Met + 3.131 * MHA-Ca)). Thus,
in a product basis, bioavailability of MHA-Ca relative to DL-Met were 52% for BWG
and 57% for FC, whereas for CY, AF and BY were 43%, 87% and 50%, respectively. In
conclusion, MHA-Ca is less effective compared to DL-Met in the diet for broiler in the
phase of 21 to 42 days because of the lower values of bioavailability for performance and
carcass yield.