Digestible threonine for slow-growing broilers: performance, carcass characteristics, intestinal mucin, and duodenal morphometry

Abstract

Five experiments were conducted to estimate the digestible threonine requirements of slow-growing broilers: experiment 1, starter phase (days 10 to 28); experiment 2, grower I phase (days 29 to 49); experiment 3, grower II phase (days 50 to 69); experiment 4, finisher phase (days 70 to 84); and experiment 5, which was specifically conducted to determine the production of intestinal mucin over two periods (days 50 to 69 and 70 to 84). Different birds were used in all experiments. A completely randomized design with five treatments and four replicates was used. Treatments consisted of increasing the values of digestible threonine in the diet through basal feed supplementation with L-threonine (98.5%), which was added instead of cornstarch. The following values of digestible threonine were investigated: 0.622, 0.697, 0.772, 0.847, and 0.922% in experiment 1; 0.586, 0.662, 0.738, 0.814, and 0.890% in experiment 2; 0.570, 0.640, 0.71, 0.780, and 0.850% in experiments 3 and 5; and 0.520, 0.595, 0.670, 0.745, and 0.820% in experiments 4 and 5. The digestible threonine values presented quadratic effects on feed conversion ratio in experiments 1, 2, and 3. Digestible threonine values of 0.628 and 0.609% resulted in higher villus height and greater duodenal crypt depth, respectively. Digestible threonine values of 0.762, 0.767, and 0.733% may be recommended for the starter, grower I, and grower II phases, respectively, based on the best feed conversion ratio. In addition, a digestible threonine level of 0.694% may be recommended for the finisher phase based on the highest production of intestinal mucin.

Supplementation of a low-protein diet with tryptophan, threonine, and valine and its impact on growth performance, blood biochemical constituents, immune parameters, and carcass traits in broiler chickens

“…In contrast, Machado et al . [ 28 ] reported a reduction in breast meat yields with increasing digestible threonine in the diet. Furthermore, Ramarao et al .…”

Estimates for digestible threonine: lysine for 21 - 35-day-old female meat-type quails

“…However, there was no effect (P>0.05) on feed intake and weight gain of quails (Table 3). Machado et al (2018) also reported an increase in the ratio height of villi / crypt depth of slow growth broiler chickens as ratio digestible Threo: Lys increased in the diets. Association of the above factors may better explain the quail´s feed improvement during this phase.…”

Lactiplantibacillus plantarum Postbiotics: Alternative of Antibiotic Growth Promoter to Ameliorate Gut Health in Broiler Chickens

“…Crude mucin concentration in the excreta was measured 3 days consecutively before the sampling day proposed by Horn et al ( 22 ) and Machado et al ( 23 ). Fresh excreta were collected randomly from each replicate 2-times daily (8 am and 4 pm) in a Falcon tube and quickly chilled at 4°C.…”

“…Crude mucin concentration in the excreta was measured 3 days consecutively before the sampling day proposed by Horn et al (22) and Machado et al (23). Fresh excreta were collected randomly from each replicate 2-times daily (8 am and 4 pm) in a Falcon tube and quickly chilled at 4 • C. Before collection, a clean and the sanitized plastic canvas was placed under cages to collect fresh and excreta without contamination.…”