Broilers fed a low protein diet supplemented with synthetic amino acids maintained growth performance and retained intestinal integrity while reducing nitrogen excretion when raised under poor sanitary conditions

The present study investigated the effects of supplementing a low protein (LP) diet supplemented with key essential amino acids (AA) to broilers on growth performance, intestinal tract function, blood metabolites, and nitrogen excretion when the animals were maintained under various sanitary conditions for 35 D after hatching. Three hundred eighty-four one-day-old male broilers (Ross 308) were randomly allotted to groups that received one of 6 dietary treatments in a 2 × 3 factorial arrangement (i.e., 2 environmental conditions and 3 dietary treatments) to give 8 replicates per treatment. Broilers were challenged with 2 environmental conditions (sanitary vs. poor sanitary). The dietary treatments were (1) high protein (HP) diet, (2) LP diet, and (3) LP diet with synthetic key essential AA (LPA): the LP diet was supplemented with synthetic AA up to the required levels for broilers. On day 14, birds consumed the LP diet impaired growth performance compared with those fed the HP diet, while the average daily weight gain-to-feed conversion ratio of birds fed the LPA diet improved to the level of birds fed the HP diet under poor sanitary conditions (P < 0.05). Broilers raised under poor sanitary conditions and fed the LP diet displayed higher (P < 0.05) zonula occludens (ZO-1) expression on day 14 than broilers fed either the HP or LPA diet. Under sanitary conditions, birds fed HP and LPA diets showed higher villus height and crypt depth compared with those of broilers fed the LP diet on day 35. Moreover, broilers raised in the poor sanitary environment had higher (P < 0.05) serum endotoxins than those raised in the sanitary environment. Broilers fed the LPA diet showed reduced (P < 0.05) nitrogen excretion on days 14 and 35 compared with those fed the LP and HP diets independent of the environment. In conclusion, the LPA diet did not impair growth performance under poor sanitary conditions for 14 D after hatch while resulting in lower nitrogen excretion in any environment conditions throughout the experiment

Optimum inclusion rate of barley in diets of meat chickens: an incremental and practical program

Context. Barley can be included in poultry diets as a cost-effective energy-contributing ingredient. However, its inclusion in meat chicken diets is limited because it is considered a viscous grain due to high crude fibre and soluble non-starch polysaccharide contents. Aims. The study quantified the optimum inclusion rate of barley in meat chicken diets during different growing phases, using an incremental program. Methods. Eight dietary treatments followed a 4 × 2 factorial arrangement, with three levels of barley inclusion to a wheat-based diet, and a nil-barley control, with or without β-glucanase supplementation. Barley was initially included at 0% (low), 7.5% (medium) and 15% (high) in starter diets (Days 1–9), scaling up by 7.5% for each level in grower (Days 9–21), finisher (Days 23–35) and withdrawal (Days 35–42) diets. Each diet was fed ad libitum to six replicate pens of 18 chicks. On Day 42, four birds per replicate pen were euthanised to determine carcass yield and collect digesta. Key results. During the starter period, a significant (P < 0.05) barley × β-glucanase interaction resulted in lower bodyweight gain (8%) and higher feed conversion ratio (8.5 points) at 15% barley inclusion without β-glucanase, whereas performance was restored with β-glucanase supplementation. No treatment interaction was apparent on growth performance assessed over the entire production period (Days 1–42). Barley inclusion at medium and high levels increased bodyweight gain, and at all levels improved feed efficiency (P < 0.01) compared with the control. β-Glucanase improved (P < 0.05) feed efficiency. Highest (P < 0.01) breast meat yield was measured for diets with medium barley inclusion. There were no interactive or main effects on duodenal digesta viscosity. Barley inclusion increased distal ileal digesta water content by ~8–10% (P < 0.05). Conclusions. Incremental inclusion of barley from 15% in a starter diet, scaling up to 37.5% in a withdrawal diet, does not compromise growth performance or carcass yields in broiler chickens. β-Glucanase supplementation favours both bodyweight gain and feed efficiency. Medium level of barley inclusion favours breast meat yield. Implications. Barley can be considered an economical grain to formulate cost-effective diets for broiler chickens. An incremental program is a practical approach to optimise barley inclusion rate