فصلنامه تحقیقات تولیدات دامی
سال سوم شماره 4 (زمستان 1393)

A comparative study was conducted on data gathered from 45 farms located in different geographical regions of Iran (Guialn province vs. the others) in order to investigate factors affecting the economic performance of broiler chicks. Slaughter age (51.25 vs. 55.04 d), mortality (5.2 vs. 9.8 %) and FCR (1.9 vs. 2.1) in Guilan province were lower than the others (P<0.05). For initial (40.9 vs. 41.7 g) and final (2857 vs. 2752 g) body weights, the differences between two strains (Ross vs. Cobb) were not significant (P>0.05). Ross chicks showed better early growth and lower mortality (P<0.05) compared to the Cobb. Correlation between initial body weight and weight at the end of first week was positive and significant (c=0.44; P<0.05). A significant positive correlation (P 0.05) was found between feed intake and slaughter age (0.45), final body weight (0.44), FCR (0.53) and mortality 0.60). Results of this study showed superiority for Guilan province as a desirable location for rearing broiler chicks than the other investigated regions. Also, indicated that the two strains have different performance.

This experiment was conducted to evaluate the effect of different levels of silybum marianum seed on performance and carcass characteristics and blood parameters of broiler chickens. Research was performed in a completely randomize design with 5 treatments, 4 replicate and 12 broilers in each replicate for 42 days. The treatments consist of the control diet, and 0.5, 1, 1.5 and 2% of silybum marianum seed. To evaluate the different part of carcass and blood parameters, at the end of experiment two bird of each replicate were bleed and then slaughtered. The results of exprement showed that the highest feed intake in the starter and finisher period respectively observed in the 1(357.71) and 1.5 (1701.9) % of silybum marianum seed, and the lowest was in the control diet (312.08) and 0.5 (1426.6) % of silybum marianum seed. The highest weight gain was in the 1.5 % of silybum marianum seed (801.27) and the lowest was in the control diet 687.40). The highest relative weight of gizzard and intestine were in the 0.5 and 2 % of silybum marianum seed (3.18 and 7.65 respectively) (P<0.05) but had no effect on the other carcass characteristics (P>0.05). The lowest cholesterol (91), triglyceride (62.75) and VLDL (12.55) and the highest level of HDL (44.50) observed in the 1.5 % of silybum marianum seed. So use of the 1.5 % of silybum marianum seed had positive effects on performance, carcass characteristics and blood parameters of broiler chickens.

Effect of type of diet formulation (diet with corn and soybean or control diet، diet with wheat، barley and agricultural byproducts balanced for sulfur-containing amino acids، total lysine and threonine and a diet similar to second diet with balanced digestible amino acids) and different levels of dietary protein (recommended level of Cobb company، 10 and 20 percentages lower than the recommended level) were studied on performance and carcass characteristics of broilers within a 3×3 factorial experiment with four replicates and 360 broiler chicks. Effect of formulation type was significant (P<0. 05). Feed intake and body weight of chicks used diets with balanced amino acids were lower than those in control group (4272 g vs. 4445 g and 2156 g vs. 2254 g). Effect of crude protein level was significant on body weight and feed conversion ratio (P<0. 05). Body weight was decreased from 2357 g to 2025 g and feed conversion ratio was increased from 1. 9 to 2. 2 along with decrease in dietary protein level. Percentages of edible carcass parts and breast were greater in control (76 and 26%، respectively) than those for two other formulations (P<0. 05). Percentages of thigh، abdominal fat and giblet were lower in recommended protein level group (20. 6، 2. 1 and 3. 8، respectively) than other levels (P<0. 05). In general، the use of diet based on agricultural byproducts balanced for digestible amino acids was recommendable for improving performance، but decrease in dietary protein level could decline performance.

This experiment was conducted to study the effect of raw and autoclaved rice bran on performance, economical performance and European efficiency factor in broiler chicks using 420 one day old Ross 308 chicks in a completely randomized design with four treatments and three replicates. Corn-soybean diet was considered as control treatment and diets included 6, 12 and 18% raw and autoclaved rice bran were fed to chicks during 14 to 42 days of age. Along with increase in rice bran to 18%, feed intake and body weight gain were decreased compared with control group (4152 g vs. 4399 g and 1887 g vs. 2272 g, respectively) and feed and protein conversion ratios were increased (2.19 vs. 1.93 and 0.41 vs. 0.36, respectively; P<0.05). The feed cost was decreased significantly (P<0.05) with the use of 18% rice bran compared to control treatment (23243 vs. 27829 Rials). European efficiency factor was decreased due to the use of rice bran (P<0.05). The lowest efficiency factor was for group with 18% rice bran (224) and the greatest was for control group 277). Processing of rice bran had no benefit for improving performance of broilers in comparison with raw rice bran (P<0.05). In general, comparison of the results related to different levels of rice bran indicated that the use of 6% rice bran in broiler diets was recommendable for improving economical efficiency.

The objective of this research was to study the factors affecting the annual genetic gain resulting from an open nucleus breeding system with selection of base-born nucleus replacement ewes in two stages using base and nucleus indices, respectively. For this purpose, an open nucleus breeding system was simulated using a deterministic approach with information from Lori-Bakhtiary sheep population. First, the genetic gain from two-stage selection in basic conditions was estimated. Then, different levels of accuracies in base and nucleus and two different levels of fertility were envisaged. In basic conditions, advantage of two-stage selection over single stage selection using base index was 7.65 %. Correlation between base and nucleus indices in this situation was 0.627. Advantage of two-stage selection depended on the accuracies of selection in the two stages and varied from 4.6% (with accuracies of base and nucleus of 0.5 and 0.65, respectively) to 15.45% (with accuracies of base and nucleus of 0.2 and 0.95, respectively). Maximum advantage of two-stage selection (15.45%) resulted from low fertiliry rate (0.7) and low correlation (0.211) between indices of the two stages. In general, results showed that with lower correlations of base and nucleus indices and low fertility rates, advantage of two-stage selection is greater.

The objective of the present study was to estimate genetic parameters of body weight traits in Guilan sheep. Traits included were birth weight (BW, n=14549), 3-month weight (3MW, n=13153) and 6 month weight (6MW, n=10142). Data and pedigree information used in this study were collected during 1994 to 2012 by the Agriculture Organization of Guilan Province in Iran. The GLM procedure of SAS was used for determining the fixed effects which had significant influence on the traits under study. Herd-year-season of lambing had significant effect on under study traits. Genetic parameters were estimated with 6 different animal models using restricted maximum likelihood (REML) procedure of Wombat program. The most suitable model amongst all six models was determined based on Akaike’s Information Criterion (AIC). Results indicated the model 4 was the most appropriate model for weight traits which included direct additive and maternal genetic effects. Based on the most appropriate fitted model, direct and maternal heritabilities of BW, 3MW and 6MW were estimated to be 0.14, 0.27, 0.37, and 0.04, 0.02 and 0.03, respectively. Estimates of direct genetic correlations were 0.08, 0.01 and 0.12 between BW-3MW, BW-6MW and 3MW-6MW, respectively. Estimates of phenotypic correlations were 0.07, 0.01 and -0.30 between BW-3MW, BW-6MW and 3MW-6MW, respectively. The results of this study showed that maternal effects are significant sources of variation for body weight traits and ignoring maternal effects in the model would cause inaccurate genetic evaluation of weight traits. Also genetic progress for body weight traits is possible by selection in Guilan sheep.

This experiment was conducted to compare the effect of free and sustained release thymol on rumen fermentation characteristics, microbial protein and some plasma metabolites. Six ruminally cannulated sheep were used in a 3×3 merged Latin square design. Treatments were (a) basal diet+ 250 mg free Thymol, (b) basal diet+ 250 mg slow relrase Thymol and (c) control (basal diet without Thymol). The experiment consisted of three 14-d periods with 10 d adaptation and 4 d sampling. At sampling period, the feces were collected and at the end of each period blood sampling and rumen fluid collection were made at different times. The measured traits were: Feed digestability, NNH3, plasma and glucose concentration, ruminal pH, microbial protein synthesis and efficiency of microbial protein synthesis. Dry matter intake (985.5 g and 917.5 g per day, respectively), crude protein digestibility (82.7% and 85.6%, respectively) and plasma glucose (114.8 mg/dL and 108 mg/dL, respectively) were increased by free and sustained release thymol consumption (P<0.05). Plasma urea concentration, microbial protein synthesis and N-NH3 were decreased in 5 and 7 hours after feeding (P<0.05). Number of diplodinia was 0.38 105 in diet with free thymol and this number was lower than those in other two treatments (P<0.05). Thymol consumption improved the efficiency of dietary protein utilization by decreasing N-NH3 and increased level of plasma glucose showed a positive effect on energy utilization of animal.

This research was carried out to estimate relative ratio of different managing factors in apiaries of Alborz province. According to the statistics of Organization of Agriculture jihad Alborz Province 2011)' Alborz province had 400 beekeepers and 33600 honeybee colonies. 99 beekeepers of Alborz province in different cities were randomly selected to complete the beekeeping questionnaires. Beekeepers were divided to three groups based on their colonies number' consisted of beekeepers with less than 50 colonies, 50 100 colonies and more than 100 colonies. Obtained data were analyzed by SPSS software. The results that showed effective factors on honey production average of colonies consist on migration management, breeding management and consider of plant vegetation, and main job were (b=1.875 and P=0.002), (b=3.369 and P=0.005) and (b=5.492 and P=0.004) with R2=0.524 respectively. The effective factors on pure income consist on breeding management and notice of plant vegetation, pathogen and pest management, production and selling management, purchase and queen change were (b=79027.45 and P=0.023), (b=67067.47 and P=0.034), (b 5245.77 and P<0.001) and (b=120272.06 and P=0.091) with R2=0.735 respectively. It is concluded that the effective factors must be noticed and controlled to have higher production and income in beekeeping industry.

This experiment was conducted to determine the effect of egg yolk levels and cold shock on coated spermatozoa by using 2 × 5 factorial arrangement of the ten treatments and 5 replicates under a repeated measure randomize design. At 5 sessions, semen was collected from three ram by artificial vagina contact with a tube containing Tris- fructose-egg yolk 15%. Samples were pooled, centrifuged and removed supernatant. Aliquot was split into two groups and each one was split into 5 subgroups and after that it was added egg yolk 0, 5, 10, 15 and 20%. First group was encountered with cold shock and second group was gradually cooled up to 5◦C then samples were incubated for 72 h. Progressive sperm motility, plasma membrane integrity, viability (by Hoechst 33258 fluorescent staining) and acrosome reaction (by PNA-Alexa flur-488) were investigated at 0, 24, 48 and 72 h. Sperm viability under cold shock and gradual cooling was higher in 5% egg yolk (67.6 ±1.47and 77.3±1.47, respectively) than 0% egg yolk (59.75±1.47 and 71.2±1.47, respectively). Sperm progressive motility, plasma membrane and acrosome integrity were improved in present of egg yolk; but, there was no difference among the treatments containing egg yolk. It was suggested that 5% egg yolk was superior to keep the function of ram coated spermatozoa for storage at 5ºC in skim milk extender.