مجله علوم دامی ایران
سال چهل و چهارم شماره 1 (بهار 1392)

The present experiment was conducted to evaluate the effects of different levels of Vitamin Premix (VP)، fed during the last three weeks of a broiler rearing period (22-42 days)، on its growth performance and carcass characteristics. Four hundred 22 day old broilers received diets containing four levels of supplementary VP (0، 33. 33، 66. 66 and 100%) each at a different weeks of finisher period. The diets were formulated as based on wheat and soybean meal، with the experiment conducted on floor pens of 10 treatments and 4 replicates in a completely randomized design. The dietary treatments consisted of: T1 no VP supplement during 22 to 42 days of age; Treatments، and 4 containing 33. 33% VP،. Treatments 5، 6 and 7 with 66. 66% of VP supplement and finally treatments 8، 9 and 10 containing 100% of VPsupplement. The treatmeants were so arranged that T 2، 5 and 8 received only from 22 to 28; treatments 3، 6 and 9 only from 22 to 35، and treatments 4، 7 and 10 only from 22 to 42 days of age. The results finally indicated that VP reduction and withdrawal at 22 days of age did not impair the birds، performance during their last three weeks of rearing period (to 42 days). Decrease in the level of VP did not significantly affect the carcass characteristics (carcass yield، percentages of breast، thigh، liver، heart as wellas abdominal fat).

Effect of heat processing on the nutritive value of broiler litter، as a potential ruminant feedstuff، was studied in two pilot plans، processing through an assessment of chemical composition، protein fractionation according to CNCPS as wells digestibility making use of Tilley and Terry method. In a manufactory located in the city of Sabzevar. The average values of Dry Matter (DM)، Crude Protein (CP)، Neutral Detergent Fiber (NDFom)، Acid detergent fiber (ADFom)، ash، Ca، P، Mg، K، Na، Fe، Mn، Cu and Zn in the unprocessed broiler litter constituted 83. 5% of the fresh matter، 26. 4، 41. 3، 14. 2، 18. 6، 1. 85، 0. 97، 0. 8، 1. 0، 0. 065 % of DM، 910. 75، 332. 73، 58. 14 and 384. 4 mg/kg of DM، respectively. These values for the processed litter، respectively، amounted to 92. 9 % of fresh weight، 25. 5، 46. 2، 14. 4، 18. 6، 1. 74، 0. 95، 0. 72، 0. 94، 0. 062 % of DM، 1029. 3، 304. 25، 54. 74 and 379. 75 mg/kg of DM. As for the Semnan manufactory، the average values for the unprocessed litter were، respectively،73. 2 % of fresh weight، 28. 8، 16. 0، 17. 2، 1. 92، 1. 13، 0. 61، 1. 1، 0. 036 % of DM، 13.، 374. 0، 52. 69 and 345. 0 mg/kg of DM. Fllowing the processing operations the mentioned values changed to 82. 3 % of fresh weight، 28. 3، 49. 1، 18. 5، 17. 8، 1. 86، 0. 94، 0. 60، 0. 87، 0. 035 % of DM، 1598. 2، 338. 67، 51. 15 and 302. 6 mg/kg of DM، respectively. Protein fractions A، B1، B2، B3 and C in the unprocessed litter at Sabzevar manufactory were، respectively 51. 8، 18. 5، 17. 1، 7. 13 and 5. 01 % of CP. The values for Semnan manufactory were recorded as 50. 3، 11. 1، 24. 6، 9. 51 and 5. 4 % of CP، respectively. After heat processing، accomplished and fot both manufactories، fractions A and B1 were reduced، wtereas B2، B3 and C increased (P<0. 05). The in vitro DM Digestibility (DMD)، Organic Matter Digestibility (OMD) and ME contents for the unprocessed litter، respectively، were 799، 798 g/kg and 9. 63 MJ/kg DM for Sabzevar manufactory، and 780، 791 g/kg and 9. 70 MJ/kg DM for Semnan،s. Heating process had no significant effect on digestibility and ME (P>0. 05)، except for DMD at Sabzevar manufactory، which had singificantly decreased. The Pressing method of processing reduced (P<0. 05) DMD، OMD (771 and 773 g/kg) and ME (9. 31 MJ/kg of DM) as compared with unprocessed litter. Overall، although application of indirect heat processing of broiler litter somehow reduced CP، Mg and Cu contents، but by removal of the pathogenic organisms it can lead ot the production of a protein supplement، enriched in mineral،s as a ruminant feedstuff and which can help reduc the environmental pollution.

An experiment was conducted to evaluate the effects of 1α-OH-D3 either with or without Cholecalciferol، microbial phytase as well as different levels of dietary calcium، and phosphorus on broiler chickens، performance. A number of 576 male broiler chickens (Ross 308) were made use of in a completely randomized design of a factorial arrangement (3×2×2×3)، comprised of 36 treatments، 4 replicates of 4 chicks in each battery cage. Factors included three levels of 1α-OH-D3 (0، 5 and 10 μg/kg)، two levels of Cholecalciferol (0 and 5000 ICU/kg)، two levels of microbial phytase (0 and 500 FTU/kg)، as well as three levels of Ca and phosphorus (100، 75 and 50% of Ross broiler nutrition recommendation values). Dietary treatments were implemented within an age interval of from 1 to 42 days. Supplementation of diets of 5 and 10 μg/kg of 1α-OH-D3 reduced body weight and feed intake at 7، 35 and 42d (P<0. 01; P<0. 05). Supplementation of 500 FTU/kg of Phytase enzyme in the diet increased body weight at 7 and 14 days (P<0. 05). Interaction between 1α-OH-D3 and phytase on feed conversion ratio was significant (P<0. 01)، in a way that addition of 500 FTU/kg of Phytase to diet containing 5 μg/kg of 1α-OH-D3 improved feed conversion ratio at 28d (P≤0. 01). 1α-OH-D3 supplementation increased tibia breaking force، linearly (P<0. 01). Results indicated that addition of 1α-OH-D3 to broiler chickens، diets alleviates the risk of tibial dyschondroplasia incidence. Yet، the appropriate recommended dosage needs to be further investigated.

Birth Weight (BW) is the first trait recorded fllowing birth. It can influence the performance of the cow and as well impact the performance of the calf it,s duringits maturity. To investigate the effect of a calf,s BW on the performance of Holstein dairy cattle in Iran, the records gathered between 1967 and 2010 were obtained from the Iranian Animal Breeding Center. The data were then used to model the productive and reproductive traits including Calving to First Insemination (CFI), First Service to Conception (FSTC), Calving Interval (CI), and dystocia. BW of calves within each herd were grouped into five categories based on standard normal distribution (z≤-0.8416, -0.8416 Keywords: Weight groups, Iranian Holstein dairy cows, Productive traits, reproductive Traits, Dystocia