نشریه علوم دامی (پژوهش و سازندگی)
پیاپی 95 (تابستان 1391)

Meat in terms of providing needed proteins، food security in the country and its share of value added agriculture in agricultural sector has a special place. In this study، first steer feedlot was modeling (Holstein and racial composition) in order to estimate the optimal age for the sale of animals using a simple linear mathematical programming (static) and then decision making for livestock feeding or replacement of new one was discussed by dynamic planning. Required data was prepared by questionnaire from 5 industrial livestock in Qazvin (Holstein and racial composition) and the Statistical Center of Iran. Results showed that if an animal life considered cyclical، sixteen months is optimal; and if it is several cycles، nine months will be optimum production. For sensitivity analysis of parameters in the model، different scenarios were considered in terms of growth performance parameters، weight was more effective than other livestock parameters. Ultimately the decision making of animal feed and replacing it with a new one was evaluated using stochastic dynamic programming. Results showed that in weights 300-398، livestock nutrition should continue and therefore in average 0. 5 kg weight per day increase and in weights 405-440، new livestock must be replaced.

This trial was conducted to investigate performance of native poultry in rural areas of Fars. 2880 broilers with age of 8 weeks were distributed in six Fars province townships. The collected data were analyzed by SAS and using one way analysis of general linear model (GLM). Results showed that the average of total monthly egg laying percentage، egg weight and total egg number of period were 37. 23 6. 08%، 42. 75 4. 74 g and 140. 20 37. 64 respectively. Different climate showed a highly significant effect on aforesaid traits، whereas; the highest egg laying percentage (43. 28%)، egg weight (43. 16 g) and total egg number (164. 67) have been found in cold، warm and cold regions and the lowest of them respectively (32. 44%، 42. 30 g، 116. 03) in warm، cold and warm regions. The average of total mortality percentage in all regions were 7. 91 1. 07، whereas the highest and lowest of them were (9. 5 1. 18، 6. 53 1. 87) relevant to warm region and tempered region، respectively. There was significant effect between warm، cold and temperate region (P< 0. 05). Average of body weight at 8، 12، 18، 30، 38، 46 and 60 weeks of age were recorded 417. 99، 641. 14، 878. 44، 1262. 94، 1335. 90، 1409. 83 and 1542. 85 g. The findings of the study suggested that general management of poultry production needed to more educated for increase economic efficiency.

To investigate the effects of different levels of dietary crude protein (CP) on performance and quality traits eggs of native layer hens Khorasan، an experiment with 300 laying hens from the native stations in completely randomized design with six treatments، 5 replicates and 10 hens in each replicate in age 26 to 50 weeks was performed. Experimental treatments based on corn، soybean meal and wheat contain different levels of crude protein (17. 5، 16، 14. 5، 13، 11. 5، and 10%). Another nutrient including the energy was iso as possible. The results showed that the percentage of CP diet has no effect on egg weight (EW) and only at 10% CP significantly reduced (P<0. 05) EW. CP showed significant effect on egg production (EP) and in such a way that produced the highest EP observed in the diet containing 16% protein in overall of experiment. The lowest levels of protein (10%) decreased about 17 % in EP and this difference in the final weeks was clearly. Reduction of CP decreased significantly (p<0. 05) feed intake in groups receiving 13. 5، 11 and 10% CP. The best feed conversion ratio was observed at 16% CP (P<0. 05). Effect of CP levels on egg internal components showed that only in weeks 30 and 38 significant reduction (P<0. 05) in shell weight percent in 10% CP and in other weeks had no effect. Overall، the results of this study showed that 16% CP improved EP and feed conversion ratio in native hens and this level of CP was the better than other surfaces used in this study، especially this effect is clearer in the end weeks of product.

Data set used in this study were 6800 records of lamb’s length life and survival rate from 263 sires and 1839 dams collected from 1989 through 2009، from the Lori-Bakhtiari stud flock at Shooli station in Shahrekord. The frequency distribution for causes of culling and survival distribution function of lambs to yearling age were estimated by SAS. The results showed that 50. 47 percent of total lambs removed from the flock up to 1 year old of age. The most causes of removing lambs from the flock were extera-fattening lambs، mortality due to illness، experimental slaughter and bad phenotype، respectively. The accumulative survival from birth to yearling age of lambs was 78. 68 percent. The regression coefficient of survival from age of lamb up to yearling showed that the survival rate decreased by 0. 076 percent per day. The overall lambs mortality up to yearling age was 21. 32 percent، which occured 5. 84% in first triplet months، 8. 43% in second triplet months، 6. 23% in third triplet months and 0. 82% in fourth triplet months of life lambs، respectively. The most mortality rate occurred in first، fifth، fourth، sixth and ninth month of life lambs، respectively. Recommended to decreasing mortality rate in lambs، the managerial factors and rearing system of lambs should be improve in second and third triplet months by coplementarity feeding، because mortality rate in second and third triplet months of life lambs were higher than first triplet months.

In order to investigate the effect of consumption of sugar beet molasses on the fermentation quality and nutritive value of sweet corn stover، the three levels of molasses in a completely randomized design with five replicates were used. Three levels of beet molasses (780 g DM Kg-1) with application rates of 0، 30 and 60 kg per ton (control، 2 and 3 respectively) of fresh sweet corn stover (SCS) were allocated and silage materials were stored into plastic buckets (with 6. 5 kg capacity) and by compacting supplied. After 45 days، The apparent specificity (smell، buildings and color silage)، pH، Fleig point (FP)، chemical composition (dry matter(DM)، crude protein (CP)، ash، neutral detergent fiber (NDF)، acid detergent fiber (ADF) and digestibility of silage was measured. The results showed that all of the silages had desirable degrees in Fleig’s method. Treatment three (3. 77) had lower pH compared with the control (3. 84) (P<0. 05). The amount of dry matter in the treated silages increased with increasing level of addition molasses (P<0. 05). The average CP and ADF contents of corn stover were 7. 72 and 34. 60 percent respectively. In the silage product، the CP content had increased to 8. 2 and ADF content had decreased to 32. 41 percent. The molasses additive increased the digestibility of the silage، but the changes were non-significant. Finally، results show that application 30 Kg molasses per ton SCS were caused for increased fermentation quality and improvement in digestibility of SCSS.

The effects of various levels of dietary L-carnitine supplements (125، 250 and 500 mg/kg) on quail sperm characteristics during liquid storage was investigated. This experiment was arranged on the basis of completely randomized design using 96 Japanese quails with 4 replicates in each treatment and 6 quails in each replicate. Semen samples were collected from male quails using abdominal massage and samples per replication mixed together. Sperm characteristics including percentage of motile، viable، abnormal، pH، volume and concentration were assessed. Results showed that the effect of L-carnitine on semen concentration was significant (p<0. 05). Quails were fed rations containing 125 mg/kg L-carnitine had higher semen concentration (603. 08 million/ml) compared with other groups. The lowest semen concentration was observed in control group (518. 76 million/ml). The effect of L-carnitine on semen pH and volume were not significant (p>0. 05). The effect of L-carnitine on motility and viability percentage of sperm in Tris extender was significant (p<0. 05). Quails were fed rations included 125 mg/kg L-carnitine had higher motile (86. 92 %) and viable (89. 55 %) sperms، after 0 and 4 hours compared to other groups. The lowest motile (80. 71 %) and viable (83. 77 %) sperms were observed for control group. The effect of L-carnitine on motility and viability percentage of sperm in Tris extender، 8، 12 and 24 hours after preservation were not significant (p>0. 05). The effect of L-carnitine on abnormal percentage of sperms 0، 4، 8، 12 and 24 hours of storage were not significant (p>0. 05). Lengths of storages had a significant effect on semen characteristics (p<0. 05). In conclusion، the use of L-carnitine supplement for improving quality of Japanese quail sperm for liquid storage is recommended.

Removal of large dairy cows required high cost of replacement heifers and in contrast with development of the herds. The economic life of dairy cattle in our country is low. Our project was planned to study and investigate the reasons for culling dairy cattle from dairy farms over a hundred head of Tehran province. In this study، about 354 industrial units of dairy cattle under the National Livestock Breeding Center of Tehran province in 2009 were obtained and analyzed. Information of inactive units and under 100 heads capacity units was eliminated. The remaining units (199 units)، based on cattle population was sorted into ascending order. Different groups of units (100 to 299-300 to 499-500 to 999 and more than 1،000 head) according to their frequency in each class were divided by capacity. Then، according to the method of proportionate random 25% of units in each class were selected for statistical analysis. Results show that from 2523 dairy cows culled in 2009 in these units، the highest frequency cause to eliminate cows was abortion and reproductive failure with 29/4%. The next important causes were non-economic and Infectious Diseases، with 18% and 15/2% ranked second and third to have. The frequency of other causes includes metabolic disorders (9/8%)، mastitis (7/3%)، the excess of (5/3%)، physical damage (5/1%)، aging (3/6%)، Genetic defects (3/5%)، economic problem (2/1%) and finally Dystocia (0/8%). The result showed high relationship between capacity and culled cow (p<0/001). Also voluntary culling in groups of one to three was more than expected. This indicates better management and more successful groups in this capacity. Likewise in the fourth batch capacity، voluntary culling was 50 percent less than the expected rate. This means that the forced removal of the animals in the herd causes the farmer have no chance to selected benefit cows.

The goal of This study was identification of QTL controlling body weight in different life stage of Baluchi sheep (Birth، 3، 6، 9، 12 months) using partial genome scan. For this purpose data was collected from 11 half sib families and 8 microsattelite (BM6465، BMS1636، BM4129، BMS2321، BMS2572، BM7145، BMS4008، BM8246) in ovine chromosome. The overall individuals were 434 animals which was grouped in 11 half sib families، The range of with progeny per family was 29-54. Initially respective rams and related offspring’s were genotyped for informative microsatellite markers، and finally eight microsattelite markers were selected for subsequent QTL analysis. For statistical analysis، year، sex، type of birth، age of dam was assumed as fix effect and the day of birth or age at time of measurement was fitted as covariate for each traitin the model. QTL analyses were conducted using a univariate multi-marker for half sib families، for each trait by interval mapping approach using QTL express software. As conclusion three significant QTL was found for this breed. Genome wide permutation indicated significant QTL for birth weight between markers BMS2572 and BM2321 at 171. 8 cM، (P<0. 01)، and for 9 and 12 monthly weights at the 85. 8 and 84. 8 cM، respectively (p<0. 05) between the markers BMS1636 and BM6465. The proportions of phenotypic variance explained by QTL were 13، 9، 12. 7، 15 and 10. 5 percent for birth،، 3، 6، 9 and 12 monthly weights respectively. As significant study result of study perhaps could be good indicator for designing proper breeding program in this breed.