A team of researchers from multiple universities in Brazil examined the use of supplemental lysine (Lys) in turkey production for growth, gain, feed efficiency and carcass yield.
The group published their results in the journal of Animal Feed Science and Technology.
“The objectives of this study was to evaluate if the digestible Lys levels proposed by breeder’s guidelines are adequate to achieve the best performance in the used rearing and feed conditions,” said the researchers.
The group found that additional lysine helps boost production and feed efficiency. However, recommended levels need may need to be reset for turkeys during the initial stage of production.
“Digestible Lys levels are in the range of the nutritional guidelines for the strain used, except in the initial phase,” the researchers said. “Due to the difference in the initial recommendation, these levels should be validated in further investigations through performance trials.”
Why lysine levels?
A focus on breeding for weight gain and feed efficiency has improved the growth rate for farmed turkeys, said the researchers. The changes in growth and yield also have been tied to availability of amino acids (AA).
As growth and carcass qualities have altered to produce more lean tissue, larger amounts of digestible lysine have been needed, they said. But, previous studies on Lys requirements are outdated and set amounts below what is suggested for modern breeds.
“In some countries such as Brazil, female turkeys are slaughtered earlier (4–5 kg), and knowledge of the AA requirements for feed formulation is especially important in this phase; however, the requirements in the literature were determined mainly for heavier turkeys and most of them for male turkeys,” they said.
More information is needed about the use and amounts of Lys required to produce female turkeys as the amino acid often serves as a reference in feed formulation, said the researchers.
In the three trial phases, 800 female turkeys were given a series of five diets with varying levels of lysine, the researchers said. The first phase ran from hatching for 25 days, the second or growth phase ran from day 26-48 and the last or finishing phase was from day 49-68.
The amounts of lysine were used to offer 0.85, 0.93, 1, 1.08 and 1.5 times the lysine level set in current nutritional guidelines, they said. “The digestible Lys levels tested were 13.6, 14.5, 15.8, 16.9 and 18.2 g/kg in the initial phase; 12.2, 13.2, 14.4, 15.4 and 16.2 g/kg in the growth phase; and 9.7, 10.4, 11.4, 12.1 and 13.7 g/kg in the finishing phase,” they added.
“The basal diets were formulated based on corn, soybean meal, and poultry offal meal and supplemented with the industrial AAs such as DL-methionine, L-threonine, L-tryptophan, L-isoleucine, L-arginine and L-valine to meet the nutritional requirements of female turkeys, except for digestible Lys, ensuring that no other AA would be limiting,” they said.
Birds were weighed weekly and feed leftovers were recorded to calculate average daily gain (ADG), average daily feed intake (ADFI) and feed efficiency (FE), said the researchers. At the end of the third experiment, carcass yield (CY) also was established.
Overall, as lysine amounts increased bird ADG, FE and CY, said the researchers. ADFI was improved in the first stage, reduced as Lys amount increased in the second stage and not altered by diet in the third phase.
“The digestible Lys level for better ADG and FE were, respectively, 16.69 g/kg and 16.55 g/kg in the initial phase, 14.25 g/kg and 14.15 g/kg in the growth phase, and 12.23 g/kg and 12.07 g/kg in the finishing phase,” they said. “The digestible Lys level for CY was 12.32 g/kg.”
Lysine levels established for young female turkeys were lower than what was found in the trial, said the researchers. “These differences in the digestible Lys requirements are probably due to the genetic progress of the turkey performance, when the available literature is relatively old, or because of the difference in potential from those birds used in comparison to this study,” they added.
“Considering the same metabolizable energy (ME) concentration in the feed as in the present study, the commercial nutritional recommendations for female turkeys would be 17.30 g/kg (12.29 MJ/kg), 14.10 g/kg (12.75 MJ/kg) and 12.00 g/kg (13.38 MJ/kg) of digestible Lys in the periods from 0 to 25, 26–48, and 49–68 d, respectively,” they said. “The requirements estimated in this study based on the FE response were similar to these recommendations in the periods from 26 to 48 d (14.15 g/kg of digestible Lys) and from 49 to 68 d (12.07 g/kg of digestible Lys), but not in the period from 0 to 25 days (16.55 g/kg of digestible Lys). This difference in the recommendation from 0 to 25 d can be attributed to the metabolizable energy and digestible amino acids provided by the breeders’ guidelines which are based on adult chicken values due to the lack in information available to assign specific turkey values.”
Source: Animal Feed Science and Technology
Title: Evaluation of the digestible lysine requirements in female turkeys from 0 to 68 days of age
Authors: J. Dorigam, M. Appelt, Al. Maiorka, K. Muramatsu, R. Sens, C. Rocha, F. Dahlke,