LAUSR

We disagree with the letter to the editor entitled “Data interpretation raises risk for performance depression in broiler production” (Lemme and Mack, 2021). The Ross 308 performance objectives at 10, 23, and 35 days of age are 321, 1142, and 2235 grams for the body weight and 0.947, 1.240, and 1.473 for FCR, respectively (Aviagen, 2019a). The birds in the cited trial fed first or second inclusion level of L-Met (see Table 3 in Millecam et al., 2021) achieved performance comparable with the Ross 308 objectives. Better performance was achieved at the recommended level of L-Met plus Cys, indicating no risk to broiler production using the recommended level of LMet plus Cys. The performance data left no doubt about other nutrients becoming limiting. Data presented by Millecam et al. (2021) is measuring L-Met plus Cys requirements in 3 broiler growth phases. Each phase used new birds to allow accurate measurement of L-Met plus Cys requirements by age while avoiding carry over effects of lack of a nutrient deficit from previous phases. In the absence of a feed grade L-Met, Met plus Cys recommendations have been developed using DL-Met. Fickler et al. (2016) recommends 0.92, 0.81, and 0.76 dig Met plus Cys for starter, grower and finisher phases in male broilers (in line with the Aviagen (2019b) recommendation.). Millecam et al. (2021) suggests an optimal dig Met plus Cys of 0.69, 0.66, and 0.62%, respectively. Despite the lower requirements achieved by using L-Met, Millecam stated “the deviation might be attributed to some extent to a higher bioavailability of L-Met than DL-Met. Other factors cannot be excluded in the present study”. The authors did not compare bioavailability of L-Met with DL-Met. It is focused