الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 138 |  |  |
| | | from | 138 | | |
Abstract
This study was conducted at the Poultry farm, Department of Animal and Poultry Production, Faculty of Agriculture, Minia University, during April and May (in 2016). The aim of the experiment was to study the effect of replacing germinated barley instead of yellow corn in broiler chick diets with or without addition of commercial enzymes mixture on the growth performance, carcass traits, digestive tract measurements, meat quality and some blood parameters of broiler chicks.
A total number of one hundred ninety two unsexed one- day old Arbor acres broiler chicks were randomly distributed into 8 groups with three replicates each. All chicks were housed in batteries previously cleaned and disinfected. Average initial body weight of all treatments was almost similar. Four diets from each starter and grower diets were formulated. The first starter and grower diets were formulated based on corn-soy diet(control).Yellow corn in the starter and grower control diets were replaced with germinated barley at levels of 25%, 50% and 75%(w/w) in the second ,the third and the fourth starter and grower diets respectively. The experimental diets satisfied the N.R.C. requirements for broiler chicks (N.R.C.,1994). Starter and grower diets were supplemented with or without recommended level (500gm/ton) of commercial enzymes mixture contained xylanase, glucanase, cellulase, α-amylase, protease, and phytase. Birds in each replicate were weighted at the end of both starting and growing periods and feed consumed was recorded. Feed conversion ratios (gm, feed /gm, gain) were calculated for different experimental periods. Economical efficiency was calculated at the end of the experiment (at 6 wks. old). At the end of the experiment (at 6 wks old),three birds from each treatment having similar body weight of each treatment were chosen, starved for about 12 hours and slaughtered to measure carcass traits, digestive tract criteria and meat quality. Also, representative samples from each slaughtered birds were collected to determine some blood parameters.
The results revealed the following:-
1-Germinated barley had higher crude protein%, crude fiber % and ash% but lower nitrogen free extract compared to ungerminated barley.
2-Growth performance:
A-Body weight and body weight gain:
-Replacing yellow corn with germinated barley (w/w) in broiler chick diets at levels of 25%, 50% and 75% gradually improved (p≤0.05) body weight by about 9.47 %, 11.85 % and 14.53% and body weight gain by about 9.71 %, 12.16 % and 14.91% respectively at marketing age. (at 6 wks old).
-Enzymes supplementation into broiler chicks diets had insignificant (p≥0.05) effect on body weight and body weight gain at starting (from 0-3 wks), growing (from4-6 wks) and entire (from 0-6wks) experimental periods.
-The effect of enzymes on body weight and body weight gain of broiler chicks was not depend on the level of germinated barley in the diets.
B-Feed consumption and feed conversion ratios:
-Substituting yellow corn with germinated barley (w/w) in broiler chick diets at levels from 25% up to 75% enhanced (p≤0.05) feed consumption at starting, growing and whole experimental periods.
-Feed conversion ratios of broiler chicks were improved (p≤0.05) by replacing yellow corn with germinated barley at growing and entire experimental periods. These improvements fluctuated between 9.97% to 15.46% and 6.07 to 8.10 % at growing (from4-6 wks) and entire (from 0-6wks) experimental periods respectively.
-Neither enzymes supplementation nor the interaction (D. ×E.) had significant effects on feed consumption and feed conversion ratios of broiler chicks.
C –Protein and energy conversion ratios:
- Protein consumption of broiler chicks was gradually increased (p≤0.05)with increasing the levels of substitution yellow corn with germinated barley in broiler chick diets from 25% up to 75% (w/w)at starting, growing and whole experimental periods.
- Energy consumption of broiler chicks was decreased (p≤0.05)by replacing yellow corn with germinated barley only at starting period, but at growing and overall experimental periods was not significantly affected.
- Protein conversion ratios was deteriorated (p≤0.05) only at starting period with increasing the levels of germinated barley in the diets more than 25%,but at growing and entire experimental periods, the differences among dietary treatments in protein conversion ratios were insignificant (p≥0.05)
- Energy conversion ratios of broiler chicks were improved (p≤0.05) by replacing (w/w) yellow corn with germinated barley in the diets at growing and entire experimental periods.
- Enzyme addition into broiler chick diets as well as the interaction between diets and enzymes had insignificant (p≥0.05) effect on protein and energy consumption and the efficiency of protein and energy utilization of broiler chicks.
D –Cost of diets and economic return:
-Cost of diet /bird, absolute and relative return /bird at marketing age (at 6 weeks old) were increased (p≤0.05) by replacing yellow corn with germinated barley in broiler chick diets and the improvements in return fluctuated between12.58 % to 15.90 % over the control treatment.
- Enzymes supplementation into broiler chicks diets as well as the interaction between diets and enzymes had insignificant (p≥0.05) effect on cost of diet /bird, absolute and relative return /bird at marketing age.
3-Carcass traits and digestive tract measurements:
-Broiler chicks fed on germinated barley diets recorded higher (p≤0.05) dressing percentage, but lower (p≤0.05) liver and giblets percentage compared to those fed on the control diet at marketing age (at 6 wks old).
- Germinated barley decreased only (p≤0.05) the relative weight of duodenum, but the absolute and relative weight and thickness of jejunum, ileum and ceca and weight, length and thickness of duodenum were not significantly affected by dietary treatments.
- Enzymes supplementation into broiler chicks diets had insignificant (p≥0.05) effect on carcass traits and digestive tract measurements except the decreased (p≤0.05) thickness of ileum at marketing age (at 6 wks old).
-The effect of the interaction (D. ×E.) was significant on dressing %, gizzard and giblets percentages of broiler chicks, while its effect on other carcass traits and digestive tract measurements was insignificant.
4-Meat quality:
- Replacing yellow corn with germinated barley in broiler chick diets increased (p≤0.05) PH-values, Juice holding capacity and brightness in breast and thigh meat at marketing age .
- Enzymes had insignificant (p≥0.05) effect on meat quality of broiler chicks at marketing age (at 6 wks old).
-The effect of the interaction (D. ×E.) on PH-values of breast and thigh, brightness and juice holding capacity of thigh meat was significant but without no clear trend
5-Some blood parameters:
- Replacing yellow corn with germinated barley in broiler chick diets decreased (p≤0.05) serum triglycerides and GPT and these decreasing effects was increased with increasing the level of substitution.
- Germinated barley had insignificant (p≥0.05) effect on serum total protein and its fraction, cholesterol, glucose and GOT in broiler chicks.
- Enzymes had insignificant (p≥0.05) effect on serum blood parameters of broiler chicks at 6 weeks of age.
- The effect of the interaction (D×E) increased (p≤0.05) serum total protein and globulin in birds fed the control diet, but the reverse trend was observed in birds fed the germinated barley diets.