نشریه علوم دامی (پژوهش و سازندگی)
پیاپی 91 (تابستان 1390)

The study has been done on farms of west southern parts of Tehran on 6 categories as follow: 1-farms below 30 head milking cows، 2- 31to 60 head، 3- 61to 100 head، 4-102to 130، 5- 131to 200، 6- higher than 200 and more. The samples have been selected based on categorized discipline random sampling method which 20 percent of main population has been studied that was totally 30 herds. By two methods of questioner and direct data collection’s nutritional situation of the farms has been studied in the period of 8 continuous months. The situation of balancing of the diets and comparing it with NRC tables has been done. the results shows that amount of DMI،CP،DP،UDP and Na were 29. 8،27. 1،14. 6،38. 5 and 85. 7 percent less than required mentioned in NRC table’s consequently. It is also has been evidenced that the NEL، Ca and P 11. 5، 33. 5 and 45. 3 percent were higher that amounts of recommended by NRC. Also from mineral balancing point of view، received amounts’ of Mg، K، Fe، Mn and zinc were higher than recommendations of NRC which shows that the nutritional situations of this group of cows was not suitable and satisfied.

This study was conducted to evaluate the effects of using different urea and vegetable oil levels on performance، egg traits and blood biochemical characteristics in laying hens at 62 to 78 weeks. This experiment was conducted with two hundred and sixteen Hy Line- W36 laying hens from 62 to 74 weeks of age as 32 factors with 3 level of urea (0. 25%، 0. 5% and 0. 75%) and 2 level of vegetable oil (0 and 3%) in completely randomized design. The experimental diets included: diet with 0. 25% of urea without vegetable oil، diet with 0. 25% of urea and 3% of vegetable oil، diet with 0. 5% of urea without vegetable oil، diet with 0. 5% of urea and 3% of vegetable oil، diet with 0. 75% of urea without vegetable oil and diet with 0. 75% of urea and 3% of vegetable oil. The results of this experiment showed that there were not any significant differences among the treatments in the performance، egg traits and blood biochemical characteristics (P>0. 05) and by using of them، the reduction in amount of soybean meal and corn in their diets is possible.

The chicken growth hormone gene is considered as one of the most important candidate genes that can influence chicken performance traits because of its crucial function in growth and metabolism. In order to detect polymorphism in GH and GHR loci 160 blood samples were collected randomly from breeder hens of Mazandaran native fowls breeding station. DNA was extracted using modified salting out procedures and polymerase chain reaction (PCR) were used for amplification of fragments with the length of 1050 bp at GH and 718 bp at GHR loci. The treatment of fragments at GH and GHR loci with SacI and HindIII restriction enzymes were revealed +، - and A and B alleles، respectively. The frequencies of alleles at GH locus were + (0. 7981)، - (0. 2019) and for GHR were A (0. 9937) and B (0. 0063). The genotype frequencies were +/+ (0. 6153)، +/- (0. 3653) and -/- (0. 0192) for GH locus and AA (0. 9937) and BB (0. 0063) for GHR locus. Low heterozigosity of GH gene could be due to closed and small effective number size of flock. Phenotypic analysis showed that GH genotypes were significantly affected body weight (BW) at 12 weeks of age (P≤0. 03). Comparison of means indicated that +/+ genotypes had higher BW at 12 weeks than the other genotypes. The relationships between GHR and other GH genotypes with phenotypic data or breeding values traits were not significant (P>0. 05).

In this study، the effect of crossbreeding were studied on local cattle performance، using information Holstein and Brown Swiss crossbred cows collected from 1993 to 2003 by Animal Breeding Center of Iran (ABCI). Milk and fat yield traits were considered in this research The data were analysed by least squres method with a modle that includded fixed effects of years and season of birth، genetic groups، lactation and region. Statistical analysis using least squares methods showed significant effects of genetic groups، lactation، region، year and season of birth on milk and fat yield in crossbred cattle (p<0. 001). The average milk and fat yield were 1599. 15±90. 52 and 1989. 54±110. 15 and 2148. 94±91. 81kg 60. 71±3. 34 kg، and 82. 26±4. 59kg and 85. 27±3. 42 kg for local and Brown Swiss × Local and Holstein × Local crossbred cows، respectively. The highest values for both traits were for the cows having 87. 5% Holstein and 62. 5% Brown Swiss inheritance and lowest values for those having 12. 5% exotic inheritance. Esimates of breed and individual heterosis effects carried out with Weight Least Square method. These effects for Holstein × Local crossbred were 20. 9 and 15. 32 kg for milk yield، 867 and 651 gr for fat yield. It was cocluded that the productive potential of local cattle can be increased by using exotic semen of genetically superior sires، through intensive management and with effective disease control programme.

This experiment was carried out to study the effects of different soybean meals، with and without enzyme، on performance and egg quality of commercial (Hy-line W-36) layers in during 12 weeks of laying cycle. A total of 432 hens were arranged in a factorial arrangement of 3×2×2 based a completely randomized design with three different kind of soybean meal (Calhore، Indian، Argentina) with two levels of phytase (0 and 300 FTU/kg of diet) and two levels of multi-enzyme (0 and 500 FTU/kg of diet). The results showed no effects of soybean meals، phytase، multi-enzyme or thier interaction on feed intake، egg mass، egg production percent، egg weight and feed conversion ratio. Dietary phytase and multi-enzyme supplementation along with different soybean meals had no significant effects on Haugh unit، eggshell weight، eggshell thickness and shell weight/ surface area. The effect of soybean meals or its interaction with enzyme (multi-enzyme and phytase) was significant on specific gravity and yolk index (p<0. 05). In conclusion، the data suggest that using of different kinds of dietary soybean meal without enzyme supplementation has no effect on the performance of laying hens، and enzyme supplementation to these dietary soybean meals gave no further improvement in performance، and egg quality.

The objective of the present investigation was to study genetic variations in the exon of leptin receptor gene of Iranian cattle breeds. Blood samples were randomly collected from 53 Sistani، 129 Sarabi، 42 Najdi and 72 Golpaygani cattle breeds. Genomic DNA was extracted from blood using guanidium thiocyanate-silica gel method. A 197 bp fragment from exon 20 of the bovine leptin receptor gene was amplified using the polymerase chain reaction. Digestion of PCR products with FokI restriction endonucleases enzyme differentiates two C and T alleles. The T allelic frequency was 0. 094، 0. 225، 0. 095 and 0. 083 in Sisatni، Sarabi، Najdi and Golpaygani cattle breeds، respectively. The CC and CT genotypes were observed in all breeds but TT genotype was not found in any breed. Genotypic frequencies for CC and CT were (0. 811، 0. 189)، (0. 550، 0. 450)، (0. 810، 0. 190) and (0. 833، 0. 167) in Sistani، Sarabi، Najdi and Golpaygani cattle breeds، respectively. The Average Heterozygosity was 0. 1709، 0. 3485، 0. 1723 and 0. 1528، in Sistani، Sarabi، Najdi and Golpaygani cattle breeds، respectively. Among all populations just Sarabi was not in Hardy-Weinberg equilibrium with respect to Leptin receptor gene.

Fattening performance and carcass characteristics of Fars native male kids were studied using factorial with two factors based on completely randomize design. The first factor was two initial body weight groups (18. 3 + 3 and 27. 4 + 2. 5 kg). The second factor was energy levels of feedstuff including low، medium and high energy (1. 9، 2. 1، and 2. 3 Mcal of ME/kg، respectively). Sixty male kids were divided into six groups of ten kids in each for fattening period of one hundred days. At the end of fattening period، from each experimental group، six kids slaughtered، randomly. Average daily gains for two weight groups were 97 and 90 g (P>0. 05) and for three rations were 78، 98 and 105 g، respectively (P<0. 01). Feed conversion ratios (FCR) for two weight groups and for three rations were 8. 94، 11. 03، 12. 24، 9. 54 and 8. 57، respectively. Dressing percentage for two weight groups were 42. 9 and 45. 7 (P<0. 01) and for three rations were 44. 05، 44. 4 and 44. 5 respectively (P>0. 05). Carcass lean percentage for two weight groups were 71. 5 and 76. 3 (P<0. 01) and for three rations were 73. 9، 74 and 73. 6 respectively (P>0. 05). Carcass fat depots percentage for two weight groups were 4. 21 and 3. 54 (P>0. 05) and for three rations were 3. 49، 3. 59 and 4. 45 respectively (P>0. 05). Carcass bone percentage for two weight groups were 24. 3 and 20. 2 (P<0. 01) and for three rations were 22. 5، 22. 4 and 21. 8 respectively (P>0. 05). Internal fat depots percentage for two weight groups were 3. 79 and 4. 03 (P>0. 05) and for three rations were 3. 13، 4. 03 and 4. 57 respectively (P<0. 01). Interaction effects for two factors on fattening performance and carcass characteristics were not statistically different. It can be concluded that، performance of fattening kids with low initial body weight and high energy diet were better than those of other kids.

A study on the grazing behavior of Raeeni goats in the desert habitat was undertaken to evaluate the relationship between forage quality and preference value. Forage quality of fourteen species within four plant communities was measured during two different phenological stages of vegetative growth and seed ripening in the dry rangeland of Kahnuj. In addition، preferences of the plant species by free-ranging of goat were estimated by visual estimation during two stages. One- way ANOVA and paired t-test were applied to compare the forage quality as well as preference value between and within two stages. In addition، linear regression and Pearson correlation were used to correlate preference value and forage quality. The results showed that forage quality and their preference values were different among each other and between two different phenological stages of growth. There was no significant relationship between forage quality and preference value (p>0. 05). Finally، highly selective feeder of goats and changing the goat diet from grazing to browsing and vise versa implicate the importance of highly diversified of botanical structure and preserving of shrubs and trees in the desert habitat.