An important aspect is to have clear understanding about the inherent digestibility values of the amino acids in feedstuffs. Therefore, it is key to formulate diets on digestible amino acids basis and not on the total values. Reliable data on amino acid digestibility will not only allow more efficient and economical feed formulation but will also reduce the impact of feed formula by nitrogen excretion reduction. Formulating diets on a least-cost basis using linear programming and using ileal digestible values is the most appropriate method ensuring adequate supply of limiting amino acids and decrease protein, hence costs. Keep in mind that 0.1% of digestible methionine from soybean meal at 605€/ton is around 103€ compared to around 2.40€ from synthetic methionine sources (prices of February 2023).

Beyond the knowledge of digestible amino acids in raw material, that can be obtained thanks to Adisseo NIR service: PNE, it must be completed by applying accurate evaluation of the animal requirement in the feed formulation.

Methodology for digestible amino acids requirement determination

Adisseo has developed a dynamic method to determine digestible amino acids requirements according to weight gain of growing animals or egg mass for laying hens.

Those models on digestible amino acids requirements are based on the prediction of the individual essential amino acid requirement per day to support daily body weight gain of the animal, during a specified period. For feed formulators, this supply of amino acids must be converted in terms of inclusion rate (kg/ton or percent of feed). To ensure an accurate supply of digestible amino acids in animal feed intake, the aim is to determine the daily amount of ingested amino acid.

Recently, new data issued from around 50 new scientific articles published from 2012 to 2021 for broilers and growing pigs were added to update and strengthen the linear modeling approach linking amino acids daily intake to average daily body weight gain, considering breeds evolution.

Recommendations from those models are available via Nestor, Adisseo platform, to formulate feed the closest as possible to animals’ needs for several species, genetics, age, sex, or performance objectives.

Figure 1 shows average daily gain (ADG) and daily feed intake (DFI) of the considered strain for the period from 0 to 42 days old. Using the equation applied in Nestor model for lysine, daily lysine requirement, expressed in g per day, during the period has been calculated. It appears that the curve obtained for daily lysine requirement follows the daily growth curve until day 30. From day 30 to the end of the cycle, the growth reaches a plateau, while DFI increases almost linearly. Given this disconnection between requirement and feed intake, the most difficult task is to fit supplies in % of feed and requirements by avoiding underfeeding or oversupplying birds, to respectively maintain the performances and avoid waste.

Figure 1. Evolution of daily weight gain, daily feed intake and daily lysine requirements along the growing period

Figure 2 shows the results of the two different formulations presented above by calculating the lysine supply from the dietary percentage and the feed intake. We can see that the curves obtained from ROSS recommendation and Nestor recommendation are quite similar up to 25 days meaning that the supply is similarly ensured. However, after 25 days old, the feeding phase proposed by Nestor, which is a dynamic system, allows to better fit the lysine requirement curve and hence avoid wastage and keep supply at adequate levels to sustain performance. The calculated digestible lysine requested from 0 to 42 days for this strain has been calculated to be 48.2 g in total. With ROSS (Aviagen) phase feeding, the lysine supply is 51.1 g (+5.6 %) and with Nestor phase feeding and dynamic recommendation at 47.6 g (-1.3%). Hence, Nestor allows to be closer to the real animal needs on the whole period thanks to its flexibility.

Figure 2. Daily supply of lysine (g/day) for the different feeding periods and recommendations (ROSS or Nestor)

Comparison of amino acids recommendations for broiler formulation

Apart from Nestor (Adisseo), other nutritional requirements references are available for feed producers. Let’s compare feed formulation and feed cost following two selected references for broilers : Nestor and Aviagen – ROSS 308. (Table 1)

Table 1. Broilers’ recommendations in digestible amino acids and energy according to Aviagen (2022)¹ and Nestor (Adisseo)²and the rearing phases

	ROSS 308, Aviagen, 2022				Nestor, Adisseo, 2022
	Starter	Grower	Finisher 1	Finisher 2	Starter	Grower	Finisher 1	Finisher 2
	0-10d	11-24d	25-39d	40-42d	0-10d	11-21d	22-34d	35-42d
dLys (%)	1.32	1.18	1.08	1.02	1.30	1.30	1.04	0.84
dMet+Cys (%)	1.00	0.92	0.86	0.82	0.94	0.96	0.77	0.63
dThr (%)	0.88	0.79	0.72	0.68	0.85	0.86	0.69	0.56
dTrp (%)	0.21	0.19	0.17	0.16	0.23	0.23	0.19	0.15
dArg (%)	1.40	1.27	1.17	1.12	1.37	1.39	1.11	0.90
dVal (%)	1.00	0.91	0.84	0.80	0.98	0.99	0.80	0.65
dIle (%)	0.88	0.80	0.75	0.70	0.88	0.87	0.70	0.57
dLeu (%)	1.45	1.30	1.19	1.12	1.37	1.39	1.12	0.90
AMEn(kcal/kg)	2975	3050	3100	3125	2975	3030	3080	3125

¹ROSS nutritional specifications, 2022 (Aviagen)

²Nestor: https://nestor.adisseo.com/

A formulation exercise was conducted on a corn-soybean meal based-diet for broilers reared on 42 days. Table 2 is summarizing feed formulas following the two recommendations references. The levels of digestible amino acids in Table 1 are set as minimums in the formulas. The reared phases of each feed are different in the two guidelines systems.

Table 2. Feed formulas following ROSS 308 (Aviagen) or Nestor (Adisseo) recommendations

Raw material inclusion (%)	Starter 0-10d	Grower 11-24d	Finisher 1 25-39d	Finisher 2 40-42d	Starter 0-10d	Grower 11-21d	Finisher 1 22-34d	Finisher 2 35-42d
	ROSS 308, Aviagen				NESTOR, Adisseo
Corn	40.6	47.9	52.6	54.0	43.4	42.8	55.5	62.3
Wheat	10.0	10.0	10.0	10.0	10.0	10.0	10.0	10.0
Soybean meal 48	32.8	32.4	30.7	26.6	35.8	36.0	27.8	15.6
Sunflower meal HP	6.2	2.1		2.4	1.5	3.0	0.5	5.6
Corn gluten meal	2.1	0.1			2.0	0.5
Soya oil	4.3	4.3	4.1	4.5	3.5	4.6	3.6	4.0
Premix + minerals	3.1	1.5	2.0	1.8	3.1	2.4	2.0	2.0
AdiSodium	0.05	0.15			0.02	0.02		0.04
L-Lysine 98%	0.34	0.23	0.18	0.20	0.28	0.27	0.21	0.26
Rhodimet® AT88	0.37	0.36	0.33	0.30	0.32	0.36	0.25	0.15
L-Threonine 98.5%	0.16	0.13	0.10	0.09	0.13	0.15	0.10	0.08
L-Valine 96.5%	0.03	0.03	0.01	0.01	0.02	0.04	0.01
L-Tryptophan 98%
Rovabio® Advance Phy	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01
Nutritional values
AMEn (kcal/kg)	2,975	3,050	3,100	3,125	2,975	3,030	3,080	3,125
Crude protein	24.4	22.0	20.5	19.7	24.1	23.8	19.6	16.3
Crude fat	6.6	6.6	6.6	7.0	5.9	6.9	6.1	6.6
Av. phosphorus	0.50	0.42	0.36	0.34	0.5	0.42	0.36	0.34
PRICE (€/t)	483.55	461.85	447.31	439.97	477.13	479.68	432.19	400.93

Taking into consideration the feed intake (Aviagen average feed intake per phase), for the whole broiler rearing period, the feed cost when following Nestor is 9 cts euros lower than when following ROSS 308 recommendations. It means for 100 000 broilers: 8 767 euros less on feed cost. The cost difference starts from 35 days.

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