فصلنامه پژوهشهای تولیدات دامی
پیاپی 1 (بهار و تابستان 1389)

Genetic and phenotypic parameters for body and yearling fleece weigh traits were estimated based on 4008 records. Records gathered across year 1993 to 2007 in the Markhoz goat research stations in Saghez and Sanandaj. Parameters were estimated using univariate and bivariate animal model with restricted maximum like lihood ASREML software. Mean (standard error of means) of birth weight (BW), weaning weight (WW), 6, 9 and 12 month and yearling fleece eight were 2.56(0.01), 14.93(0.0) 17.13(0.08), 20.08(0.11), 24.72(0.14) kg and 450.51(3.46) gram, respectively. Higher and lower direct heritability were 0.361±0.041 and 0.211±0.036 for 12 month and yearling fleece weight respectively. Birth weight has the highest maternal heritability (0.121±0.023) and it was decreased with increasing of age. Genetic correlation between these traits ranged from -0.202 t0 0.862 and phenotypic correlation 0.152 to 0.835, respectively. Genetic correlations for growth traits were positive but those of some growth traits and fleece weight were negative. Correlation between direct and maternal genetic effect were negative for all traits.

A 2×2×2 factorial arrangement with control group was conducted to study the effect of different levels of microbial phytase, metabolizable energy and available phosphorus on performance, carcass characteristics and phosphorus and calcium content of tibia in broiler chicks. In this experiment, 1260 Ross 308 male broiler chicks allocated to 9 treatments in a factorial arrangement, with 2 levels of microbial phytase (0 and 500 FTU), 2 levels of metabolizable energy (recommended level and 80 kcal lower than recommended levels), 2 levels of available phosphorus (50 and 75% of recommended levels) with control group (without enzyme and recommended level of available phosphorus), with 4 replications and 35 chicks in each replicate in a completely randomized design (CRD). Use of microbial phytase had significant effect on feed intake, body weight gain in whole period of the experiment (P<0.05). Differences of energy levels had significant effect on feed intake, body weight gain and feed conversion ratio (P<0.05). There were significant differences between treatments for available phosphorus levels for feed intake (3299.5 Vs. 3714.4 g), body weight gain (1531.5 Vs. 1974.6 g), feed conversion ratio (2.17 Vs. 1.91), breast (33.02 Vs. 33.69) and thigh (35.4 Vs. 36.3) percentage, tibia ash (41.69 Vs. 43.66%) phosphorus (7.96 Vs. 8.35%) and calcium (14.65 Vs. 15.81%) content of tibia (P<0.05). Interaction of energy and phosphorus was significant on feed intake, body weight gain, feed conversion ratio and phosphorus percentage of tibia (P<0.05). Results of this experiment showed that use of 500 FTU microbial phytase, with 80 kcal/kg ME lower than recommended levels and 75% recommended available phosphorus level had the best result on performance in broiler chicks.

This experiment was conducted to determine the effect of selection index in four iranian commercial silkworm lines (107, 110, 153, 154) on resistance of their hybrids including 107×110, 110×107, 153×154, 154×153 under stress of nuclear polyhedrosis virus (N.P.V) Infection. Selection index program was performed on 3P commercial lines during 9 generations. Later generation parents of 3P lines were selected in each generation, by forming selection matrix based on heritability parameters, correlation between cocoon weight, cocoon shell weight and cocoon shell percentage and phenotypic mean of traits. In the 10th generation, 2P populations (produced by random cross of 3P) were mated randomly and P (parent) silkworm eggs were produced by random mating of 2P population. P populations in selected and random groups were reared in village conditions (growths silkworm rearing house silkworm). Control P population was produced by crossing 2P population (produced by non-selected 3P lines). F1 hybrids of control group (non-selected) were reared simultaneously. From the obtained results, the hybrids of 110×107 and 154×153 significantly showed the highest performance for individual cocoon traits (P<0.05).The best cocoon percentage, middle cocoon percentage, low cocoon percentage, double cocoon percentage, total cocoon weight, larva survival rate and pupation rate were studied, that showed negative relationship between resistance and production characteristics. The results demonstrated that selection index method have a negative effect on resistance of silkworm hybrids as well as improving production and economic performance of silkworm hybrids. It is recommended that economical coefficients and genetically parameters are estimated for productive, resistance and quantitative cocoon characters together. Then parents would be selected on the basis of those parameters.

In this study, the economic coefficient of 10 traits including birth weight, 3-month weight, 6-month weight, 12-month weight, survival before 3-month, survival before 6-month, ewe survival, cumulative survival, twining percentage and fertility percentage were investigated in four different production systems with mean number 250 ewe of karakul by bio-economic model in Fars province. The obtained results showed that 6-month weight had the highest importance among the above traits. 3-month weight, cumulative survival, twining and fertility rate, ewe survival, birth weight, survival before 3-month, survival before 12- month, survival before 6-month, had positive coefficients and 12-month weight, had negative coefficients in the following ranking.

An experiment was conducted to evaluate the effect of protein and synbiotic levels performance and carcass characteristics of Japanese quail. The experiment was done using 720 day old quail for 42 days in a completely randomized design with 3×3 factorial arrangements with three levels of protein (sufficient protein diet (24%) during whole period, low protein diet (22.08%) during whole period and sufficient protein diet during starter period-low protein diet during grower period) and three levels of Synbiotic (without, the recommended level and 150% of recommended level). All diets were isocaloric except for protein and were consisted of recommended levels of nutrients (NRC, 1994). Body weight gain, feed intake and feed conversion ratio were not differ statistically (P>0.05), due to interaction of protein and synbiotic levels. Body weight gain and energy efficiency ratio in starter and whole growing periods was lower (P<0.05) in quails received diets containing low protein in starter period. Feed conversion ratio and performance index in whole period was imperoved (P<0.05) in teratments with higher level of protein in starter period. Reduction of protein content of diets during growing period had not significant effect on these parameters. Protein efficiency ratio improved (P<0.05) with decreasing protein level, while synbiotic levels were not differing among treatmeats. Protein and synbiotic levels and their intraction had not significant effect on carcass characteristics.

The objective of this study was to investigate the effect of different levels of glycerol on Dallagh rams semen characteristics in pre and post freezing conditions. Semen samples were collected from 4 healthy and mature rams using an electro ejaculator, were mixed with Tris extender in a ratio of 1:4 semen and assessed at 5°c. 0.5 ml of straws were filled with diluted semen and kept above liquid nitrogen vapor within 7 minutes and after 10 days were thawed to investigate live and motility percentage of spermatozoa and morphological characteristics. The experiment was carried out on the basis of completely randomized design with 3 treatments including 3 levels of glycerol (4, 6, 8%) and 9 replicates. Results showed that the effect of glycerol on live and motility percentage of pre and post freezing spermatozoa was significant (P<0.05), but had not significant effect on morphological characteristics of spermatozoa (P>0.05). The highest survival and motility percentage and the lowest morphological defects of spermatozoa were obtained in 4% glycerol. Therefore using 4% glycerol in Tris extender is recommend for semen storage of Dallagh rams in pre and post freezing conditions.

This study was carried out to syrvey the effects of conjugated linoleic acid (CLA) on chicken meat traits and sensory characteristics. The fat sources of five experimental treatments were: 7% soybean oil, 7% CLA, 3.5% soybean oil + 3.5% CLA; 10% palm oil; and a control fat free diet. These diets were used at grower (11-28 d) and finisher (29-42) periods. The Study was carried out as a compeletly randomized design with 5 treatments, four replicate consisted of 15 mixed sex chicks (Ross 308). At first 10 days of experiment all the chickens used a basal fat free diet. The results showed that, dietary fat type didn’t have significant effect on chicken meat taste. unexpectfully, diets containing CLA didn’t decreas abdominal fat pad, although reduced the chicken meat interior fat. Using CLA especially at 7% level adversely affected some physical aspects of meat like juicy, firmness and ease of chewing. Nonetheless, it seems that there is no direct relationship between dietary CLA level and chicken meat crude fat reduction, because the lower dietary CLA concentration resulted to more significant reduction of fat.