No abstract

No abstract

No abstract

1. In an experiment on broiler cockerels, the influence of tannic acid (TA) and polyethylene glycol (PEG) on body weight gain (BWG), feed conversion ratio (FCR), weight of intestine and liver, the activities of serum enzymes LDH, AST, ALT and intestinal absorption function were investigated. 2. Broiler cockerels were given either a commercial diet alone (control group) or a commercial diet with TA (20 g/kg), PEG (10 g/kg) or TA plus PEG (20 + 10 g/kg), for 10 d. 3. On the last day of the experiment, all birds and remaining feed were weighed individually and a sample of blood was taken to measure the serum activities of lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT). The capacity of intestinal cells for the absorption of D-xylose was measured. Finally all birds were killed humanely and the intestine and liver were weighed. 4. The results showed that TA significantly reduced BWG and FCR, as well as the activity of LDH, AST and ALT. 5. TA also increased the relative weight of the intestine. Adding PEG alone had no effect on any of the measured parameters. 6. However, PEG improved significantly BWG, FCR and the activity of LDH and AST of TA-fed birds. 7. The plasma D-xylose concentration of experimental birds was similar for all dietary treatments most likely because of temporal separation between feeding the dietary TA and administering the D-xylose. 8. It was concluded that the presence of tannins in the GI lumen of the bird was necessary to affect the processes involved in the absorption of simple sugars such as D-xylose, at the level of intestinal absorptive cells.

Four experiments were conducted, in two stages, to evaluate protein and limiting amino acids' (lysine and methionine + cystine) levels in pre-starter diets on broilers' performance. In each experiment of Stage 1, 640 new-born male Ross 308 cockerels were randomly allocated to eight dietary treatments with a 2 × 4 factorial arrangement. In experiment 1-1, two levels of crude protein (CP: 21% and 23.2%) and four levels of Lys (1.2, 1.3, 1.4, and 1.5%) and in experiment 1-2, two levels of CP (21 and 23.2%) and four levels of Met + Cys (0.85, 0.90, 0.95, and 1.00%) were used. In Stage 2, the optimum levels of Lys and Met + Cys obtained from Stage 1 (1.3 and 1.5% Lys, 0.90 and 1.00% Met + Cys in experiment 1-1 and 1-2, resp.) with two levels of CP (21 and 23.2%) were used in two separate simultaneous experiments with a 2 × 2 factorial arrangement for male and female birds. The levels of CP significantly influenced BWG and FCR in experiment 1-1. Dietary levels of Lys affect BWG (experiment 1-1) and FI (experiments 1-1 and 2-1) significantly. In experiments 1-2 and 2-2, the different levels of Met + Cys did not affect BWG, FI, and FCR of male or female broilers. The results of these experiments indicated that the optimal level of dietary protein and Lys were 23.2% and 1.5%, respectively. Diets with 1% Met + Cys caused optimal performance.