Methodology to calculate amino acid requirements in e-Rhodimet® Nutrition Guide (eRNG)
Commonly, amino acid requirements are estimated in experimental trials using optimized criteria such as daily weight gain, feed conversion ratio and breast meat yield in different mathematical models (quadratic, broken line, exponential). These trials determine the requirement in each amino acid for a given duration or physiological stage, expressed as percentage of feed without taking into account the amount of feed intake (Goulart et al., 2011). Other authors have predicted the amino acids requirements, expressed as percentage of feed or ratio to lysine, using meta-analyses performed on dose-response studies (Simongiovanni et al., 2012).
Adisseo proposed an innovative model approach for determining amino acids requirements depending on the weight gain and the exact amount of ingested amino acid needed to sustain this weight gain (Nonis et al., 2013). This work assumes that independently to the animal’s genotype, a constant quantity of amino acid per day is necessary to obtain a given daily weight gain. Therefore, using data published over a 22-year period, Adisseo developed a model based on the amino acid intake expressed as a response to the daily weight gain. This method allows the calculation of the individual amino acid requirements for a given performance, which is more in line with the precise nutrition approaches promoted nowadays. The tool eRNG developed by Adisseo proposes such calculations to nutritionists and formulators.
Validation of the recommendations for methionine+cysteine of broilers given by the eRNG
A trial was performed to validate the recommendations in methionine (Met) and methionine + cysteine (Met+Cys) given by the eRNG in broilers using a quadratic plateau model (Batonon-Alavo & Mercier, 2017). Seven hundred and twenty Ross PM3 male chickens were reared in floor pens from 0 to 14 d and 14 to 28 d, respectively. Birds were randomly allocated to 6 treatments with 8 replicates of 15 birds each. Treatments consisted of a basal diet deficient in Met+Cys and five treatments supplemented with graded levels of DL-Met (0.07, 0.14, 0.21, 0.28, and 0.35%) in 2 phases (0-14 d and 15-28 d).
Independently to the period considered, methionine addition significantly improved all performance criteria in comparison with the basal diet. Body weight gain and feed conversion ratio improved with methionine addition until a plateau was reached. These results were in accordance with several studies demonstrating that addition of methionine into a deficient diet improved broiler performance (Agostini et al., 2016; Goulart et al., 2011).
Quadratic plateau models were applied respectively to the daily weight gain and the feed conversion ratio in response to daily Met+Cys intakes. Slight differences from the eRNG were observed from 0 to 14 d, with higher values observed with the quadratic model. Yet, these estimations of Met+Cys requirements are in line with the ones reported by Dozier and Mercier (2013) for the 1-15 d period. The differences observed with the eRNG predictions in the first 14 d might be related to the low number of data available in the literature on this period. From 14 to 28 d period, the requirements are similar to the recommendations determined using the eRNG, especially when predictions are based on the feed conversion ratio (Figure 1 and Figure 2).
Figure 1. Quadratic modeling of daily weight gain as function of daily Met+Cys intake, for the 0-28 d period (from Batonon-Alavo & Mercier, 2017)
Figure 2. Quadratic modeling of feed conversion ratio as function of daily Met+Cys intake, for the 0-28 d period (from Batonon-Alavo & Mercier, 2017)
Figure 3. Linear regression between measured recommendations in Met (g/d) and Met+Cys (g/d) and predicted recommendations from the eRNG for broilers fed from 0 to 28 d (from Batonon-Alavo & Mercier, 2017).
The recommendations determined in the trial reported herein validate the ones given by the eRNG and confirm the relevance of the approach of estimating amino acid recommendations using the exact amount of feed ingested and the growth performance expected (Figure 3).
Comparison to other amino acids recommendations
Apart for the Rhodimet® Nutrition Guide edited by Adisseo, other nutritional requirements references are available for feed producers. Aviagen proposed nutritional specifications for its broiler Ross 308. Lemme et al., from Evonik released in 2010 nutritional recommendations for amino acids for various rearing animals. A trial was performed on Ross 308 broilers chickens to compare the three nutrients recommendations (Nonis et al., 2013). 384 male chickens were reared during 42 days, divided into three rearing periods: 0-12 d, 13-22 d and 23-35 d. Diets were formulated according to three types of digestible amino acids recommendations: Evonik (Lemme et al., 2010), Ross 308 (Aviagen, 2014) and Adisseo RNG (2013), see Table 1. Birds were randomly allocated to 3 treatments with 8 replicates of 16 birds each.
Final body weight, weight gain, feed intake or Feed Conversion ratio were found to be similar on the whole rearing period for all animals, with no difference regarding the nutritional recommendations taken into account. However, the feed cost per gain of broilers was significantly lower for the groups fed in accordance to eRNG requirements compared to Evonik and Ross 308, as shown in Figure 4.
Figure 4. Impact of amino acids recommendations on feed cost per gain of broilers
The global feed cost when following Rhodimet® Nutrition Guide is 0.09 euros/kg lower than Evonik and 0.011 euros/kg lower than Ross 308. This is particularly true on the second rearing phase of finisher where the biggest gap with Evonik and Ross amino acids requirements is observed (respectively 0.016 and 0.042 euros/kg difference in favor of RNG). The three nutritional recommendations led to the same animals’ performance with a lower feed cost at the advantage of eRNG guidelines.
Formulating broiler diets based on the amino acid recommendations of the eRNG optimized on Feed Conversion Ratio allows a better adjustment of digestible amino acid requirements to sustain broiler growth and an economic interest especially in the finishing period compared to some other available recommendations.
eRNG is now available on smartphone, in addition to tablet. You can also use it on computer. In China, it is usable through Adisseo Wechat. More information on Adisseo feedsolutions
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