The modern broiler chicken performance is mainly driven by the digestible lysine levels. Based on the recent study conducted by the University of Sydney, increasing 3% digestible lysine level will improve chicken body weight by 175 grams within 42 days. It will also increase the feed cost by 15, 17, 13, and 13 AUD per MT feed, in the starter, grower, finisher, and withdrawal period, respectively.
Exogenous protease supplementation in broiler chicken diets have primarily been attributed to improvements in protein and amino acids digestibility. Therefore, nutritionists are likely to know if adding the exogenous protease could save some amino acids and quantify its amino acids digestibility. In particular, after non-starch polysaccharides enzymes and phytase have been widely accepted in the feed formulation, there is still the room for the protease to further improve the amino acids digestibility.
In the University of Sydney, a study with three treatments was conducted. Standard, positive control (PC) diets were formulated to meet or exceed the 2019 Aviagen Ross 308 nutrition specifications and negative control (NC) diets were formulated with a 5% reduction in both crude protein and digestible essential amino acids. A third treatment group consisted of the NC supplemented with the exogenous protease. All diets contained 1000 FTU phytase and 4000 U of xylanase.
Overall broiler growth to 35 days post-hatch exceeded the Ross 2019 male performance objectives by 10.6% for weight gain (2580 versus 2333 g) and was superior by 5.66% in FCR (1.401 versus 1.485). The body weight gain (1-35 days) result was show in Figure 1. It is clearly shown that adding the exogenous protease can not compensate 5% amino acids reduction but can save 2.7% amino acids. Therefore, adding the VTR’s exogenous protease to diets containing phytase and xylanase can still increase 158 grams per bird within 42 days and save the cost more than 10 AUD/MT feed.
Fig 1. Bodyweight gain in male Ross 308 broilers from 1-35 days post-hatch (P = 0.018).
Fig 2. The body weight gain in response to increased digestible lysine levels.