Effect of zinc bacitracin and phytase on growth performance, nutrient digestibility, carcass and meat traits of broilers.

A total of 336 one-day-old Hubbard broiler chickens were randomly distributed among 8 groups, each containing six replicates (7 chickens/replicate). From 1 to 40 days of age, the groups fed the same starter, grower and finisher diets. The control group was unsupplemented; zinc bacitracin (ZnB) group received the antibiotic at 0.5 g/kg; fungal phytase (FP) groups received 250, 500 and 1000 U/kg diet of Aspergillus niger phytase (FP_250, FP_500 and FP_1000 groups), respectively; bacterial phyatse (BP) groups received 250, 500 and 1000 U/kg diet of Escherichia coli phytase (BP_250EP, BP_500EP and BP_1000EP groups) respectively. Considering the whole experimental period, body weight gain was unaffected by ZnB and different concentrations of bacterial and fungal phytase; however, the feed conversion ratio of the group fed a diet supplemented with 500 U of BP was better (p < 0.01) than those fed with a diet supplemented with 500 U of FP. BP_250 group had a higher (p < 0.05) apparent digestibility of ether extract compared to FP_250 group. In conclusion, bacterial phytase at 500 U may enhance performance of broiler chickens fed during days 1-40 of age and yield similar growth performance and economic efficiency to those of eB-supplemented groups.

Effect of ascorbic acid or increasing metabolizable energy level with or without supplementation of some essential amino acids on productive and physiological traits of slow-growing chicks exposed to chronic heat stress.

Four hundred and twenty, 21-day-old slow-growing chicks were divided randomly into seven treatments, each containing five replicates. Each replicate was kept in a 1 × 1-m floor pen. One treatment was kept under thermo-neutral conditions in a semi-open house and fed a corn-soybean meal diet (positive control). The other six groups were kept under chronic heat stress (CHS) at 38 °C and 60% RH for 4 h from 12:00 to 16:00 pm for three successive days per week. Chicks in CHS treatments were fed a corn-soybean meal diet without (negative control) or with increasing metabolizable energy (ME) level by oil supplementation alone, or also with increasing some essential amino acids (EAA) such as methionine (Met), methionine and lysine (Met+Lys) or methionine, lysine and arginine (Met+Lys+Arg) or supplemented with 250 mg of ascorbic acid (AA)/kg. CHS impaired (p < 0.05) growth performance, increased plasma triglycerides and total serum Ca while decreasing (p < 0.05) plasma glucose and total serum protein. Meanwhile 250 mg AA/kg diet or an increasing ME without or with some EAA partially alleviated (p < 0.0001) the negative effect of CHS on growth while increasing (p < 0.05) feed intake and improving (p < 0.05) feed:gain ratio (F:G) and crude protein (CP) digestibility (p < 0.05). AA or increasing ME with or without EAA increased (p < 0.05) percentage dressing, liver and giblets to those of the positive control. AA or increasing ME with or without EAA partially alleviated the negative effect of CHS on blood pH, packed cell volume (PCV), haemoglobin (Hgb), total serum protein and total Ca, plasma glucose and triglyceride, rectal temperature and respiration rate. Increasing ME level improved chickens' tolerance to CHS without a significant difference from those supplemented with AA. However, increasing Met, Lys and Arg concentration did not improve performance over that recorded with increasing ME level alone. Under CHS, 250 mg AA/kg diet or increasing ME level by addition of 3% vegetable oil could be an useful approach to improve productive and physiological traits of slow-growing chicks, which may be applicable also to fast-growing one.

Effect of amount and source of manganese and/or phytase supplementation on productive and reproductive performance and some physiological traits of dual purpose cross-bred hens in the tropics.

1. The effect of different amounts of added manganese (Mn) (0, 10, 20 and 40 mg/kg) in inorganic and organic form and phytase (0 and 300 U) was investigated on productive, reproductive and haematological traits on 480 hens and 60 cocks (Inchas breeds) divided into 12 groups: 10 and 20 Mn x 0 and 300 phytase x 2 Mn sources (8 groups), two negative controls (0 Mn x 2 levels of phytase) and two positive controls (40 Mn x 2 Mn sources). 2. Phytase supplementation increased laying rate by 1.1% and egg weight by 0.4 g. 3. Manganese supplementation at 10 mg/kg over dietary sources improved hatchability, at 20 mg/kg decreased death embryos and abnormality as those of hens supplemented with 40 mg/kg Mn. Inorganic Mn at 10 mg/kg significantly increased egg mass compared to the organic form. Inorganic Mn was more efficient in decreasing abnormal chicks than organic Mn. Phytase supplementation significantly increased hatchability of fertile eggs and decreased the number of abnormal chicks of groups fed on diets unsupplemented with Mn and those supplemented with 10 mg/kg Mn. 4. Mn supplementation at 10 mg/kg over dietary sources significantly improved sperm mass motility and decreased abnormal sperm. Phytase significantly decreased lymphocyte cells and plasma AST. 5. Mn supplementation of the control diet (containing only 16 mg/kg from raw materials) with 20 mg/kg of Mn from either organic or inorganic source is adequate to support egg production traits, egg quality, reproductive traits and economic efficiency of dual purpose cross-bred hens; however, phytase supplementation may reduce the required Mn supplementation to 10 mg/kg.

Improving productive and reproductive performance of dual-purpose crossbred hens in the tropics by lecithin supplementation.

In order to study the influence of lecithin and vegetable oils on improving productive and reproductive performance, egg quality, and metabolic profile of dual-purpose crossbred hens in the tropics, a total of 224 hens, 47-wk old, 112 each of Gimmizah and Silver Montazah strains were fed seven isonitrogenous diets. Experimental treatments consisted of feeding seven different diets to layers; four isocaloric diets containing either no added lipid (control), 3% vegetable oil mixture, 3% soy lecithin or 6% soy lecithin; and three high-energy level diets, containing an extra 3% vegetable oil mixture, 3% or 6% soy lecithin added to the control diet. Thus, the experimental design was factorial, consisting of seven lipid treatments by two strains of hens. Results indicate that 3% lecithin as an extra ME source, or feeding 11.72 MJ ME/kg diet containing the same level of lecithin, improved productive and reproductive performance of crossbred hens. Moreover, lecithin at 6% as an extra ME supplement significantly increased yolk percentage and improved Haugh unit score and yolk color, while increasing EE digestibility and plasma total lipids. Hen strain had a significant effect only on digestibility of OM, percentage liver and Haugh unit score, with the Gimmizah strain having higher values.