فصلنامه تحقیقات تولیدات دامی
سال چهارم شماره 1 (بهار 1394)

A total of 216 white Hy-Line laying hens (57 wk of age) were used for 8-wk period to investigate the effect of different levels of energy and enzyme β-mannanase in the corn-barely-soybean based diet on performance and egg quality parameters. This experiment was conducted in a completely randomized design as factorial experiment (2 × 2) with 9 replicates. Treatments consisted of two levels of energy (2850 and 2750 Kcal/kg diet) and 2 levels of enzyme β-mannanase (with or without enzyme). The results showed that the the use of high-energy diets (2850 kcal/kg) in comparison with low-energy diets (2750 kcal kg) reduced feed intake 95. 6±3. 9 vs 97. 9±2. 0 g; P=0. 038) and increased yolk color index (5. 7±0. 6 vs 5. 1±0. 7; P=0. 044). However، other production traits and egg qualitaty parameters were not affected by dietary energy level. Although the effect of β mannanase enzyme on production parameters and egg quality traits were not significant، there were the trends for decreasing the percentage of broken eggs (P=0. 072) and improving eggshell thickness (P=0. 086) with supplementing β mannanase to the diet. Significant interactions between energy and enzyme were also observed in term of shell thickness during the whole experimental period، so that low-energy diet with enzyme significantly improved the eggshell thickness compared with low-energy diet without enzyme (P=0. 049). According to the results of current study، the use of β-mannanase enzyme is recommended to improve the eggshell quality characteristics in low-energy diet based on corn-barelysoybean diet.

An experiment was conducted to evaluate the effect of Watercress extract on rooster sperm storage at 4 °C by using 15 mature roosters. Semen collection was performed twice a week in 5 times. In each session, ejaculates were pooled and split into five parts. The amount of 0, 300, 600, 900 and 1200 μg/mL Watercress extract were added to each part. After that, samples were chilled to 4 °C and kept until 72 h. Sperm viability (by staining Hoechst 33258), motility and membrane integrity were evaluated at 0, 24, 48 and 72 h. To determine lipid peroxidation, the concentration of malondialdehid (MDA) was evaluated by using 300 106 spermatoza at 48 h. The results showed that the lowest of concentration of MDA (1.0 μM/mL) was in 600 μg/mL Watercress extract (P<0.05). The main effect of watergrass on sperm viability showed that viability of spermatozoa was lowest (73.4%) in 1200 μg/mL Watercress extract level (P<0.05). There was interaction between Watercress extract and storage time on sperm motility and membrane integrity (P<0.05). After 48 h incubation, membrane integrity was higher in 600 μg/mL (90.70%) Watercress extract than control (85.80%; P<0.05). At 72 h, there was no difference between 600 (51±3.36) and 300 (42.60±3.01) μg/mL Watercress extract on sperm motility (P>0.05) and it was higher in 600 μg/mL Grass water extract than other treatments (P<0.05). Therefore, the addition of 600 μg/mL Watercress extract to semen improves longevity of rooster spermatozoa at 4 C.

IL8RB gene is one of the chemokine receptors presented on neutrophil surfaces whichare necessary for maximizing of neutrophils ability during infection. Different sequence and expression of IL8RB gene lead to different resistance to mastitis in cow populations. The aim of current study was to investigate expression changes of IL8RB gene resulted from crossbreeding of Guilan Native cows with Holstein cows. We collect 56 blood samples from 5 different cow populations in Guilan Native cattle breeding center. After RNA extraction and cDNA synthesis, realtime PCR reactions were performed in all samples with three repeats for each sample. We used GAPDH and RPLP0 as internal reference control genes. The maximum amount of IL8RB gene (0.74±0.77)average normalized expression was in Native cow populations and the minimum expression (0.12±0.22) was in 75 percent Holstein crossbred cow populations. Highest to lowest amount of IL8RB gene average normalized expression was in Native cow (0.74±0.77), 50 percent sire Native and dam Holstein crossbred cow (0.3±0.27), 50 percent sire Holstein and dam Native crossbred cow (0.26±0.3), Holstein cow (0.23±0.26), and 75 percent Holstein crossbred cow (0.12±0.22), respectively. With Consideration of highest gene expression in Native cow and decreasing in gene expression respect to increasing in blood contribution of Holstein cow which they are sensitive to mastitis, consequently changes in gene expression of IL8RB are related to resistance to mastitis. As this study showed the effect of crossbreeding on IL8RB gene expression changes, then it is necessary to consider the consequences of crossbreeding on native cattle breeding program.

This study investigated genetic variation within indigenous Camelus dromedarius in north of Kerman province using five microsatellite markers (VOLP03, VOLP08, YWLL08, YWLL38 and CVR01). The blood samples were collected from 81 camels of Shahr Babak, Rafsanjan and Ravar (5 populations). Phenol - chloroform extraction method was used to isolate the DNA. The highest and the lowest allele number and effective alleles are shown in YWLL08 (14 and 10.54) and CVR01 (5 and 4.35), respectively. The expected heterozygosity varied from 0.9108 (YWLL08) to 0.7754 (CVR01). The Hardy-Weinberg equilibrium (HWE) test showed that all loci deviated from HWE (P<0.05). Polymorphism information content ranged from 0.7801 to 0.9165. Fixation index (FST) values for markers YWLL08, VOLP03, VOLP08, YWLL38 and CVR01 was obtained respectively 0.036, 0.089, 0.073, 0.046, 0.054 and 0.056 that indicates the distinction is too much between the populations. The results of the current study indicated that the Camelus dromedarius in the North of Kerman province populations have a relativity high genetic variation, which makes them compatible to drastic environmental changes existing in Kerman province. Therefore, it is essential to maintain this genetic diversity and this valuable animal.

In this research genetic trends for body weight traits of Shal lambs, including: birth weight (BW), weaning weight (WW), 6-month weight (6MW), 9-month weight (9MW) and yearling weight (YW) were studied over a 16-year period. Genetic parameters were estimated using restricted maximum likelihood (REML) method under animal model and breeding values of animals were predicted with Best Linear Unbiased Prediction (BLUP) methodology with single-trait and five-trait animal models. Genetic trends were estimated by regressing the mean of breeding values on year of birth. Direct heritability for BW, WW, 6MW, 9MW and YW were estimated 0.32, 0.47, 0.32, 0.41 and 0.28, respectively. Genetic trends for these traits from both single- and five-trait analyses were estimated (-3 and 4), (32 and 35), (-18 and 10), (27 and 28), (-3 and 11) g per year, respectively, and were non-significant (P>0.05). Also, genetic progress for these traits from both single- and five-trait analyses were calculated (1 and 118), (316 and 918), (404 and 438), (522 and 672) and (60 and 379) g in studied period, respectively. The highest genetic trend was for WW, which had the highest heritability. Despite relatively high heritability for all studied traits, insignificant genetic trends for these traits indicate an undesirable selection program in Shal sheep.

The objective of the present study was to estimate genetic parameters and genetic and phenotypic trends of body weight traits from birth to yearling ages Mehraban sheep. Traits included were birth weight, weaning weight, 6- month weight, 9-month weight and yearling weight. The data included 10278 lambing records and pedigree information used in this research were collected at the Breeding Station of Mehraban sheep (Hamedan provice, Iran) during 1994-2011. Genetic parameters were estimated using restricted maximum likelihood procedure of the Wombat program and the SAS program was used for editing and analysising data. Direct heritabilities for BW, WW, 6MW, 9MW and YW were estimated as 0.25±0.04, 0.46±0.05, 0.59±0.08, 0.57±0.08 and 0.11±0.08, respectively. The heritability estimates of these traits suggested the most suitable trait for conducting direct selection were WW for pre-weaning and 6MW for post-weaning period. Direct genetic correlations between birth weight with other body weights ranged from -0.02 between BW and 9MW to 0.95 between 9MW and YW. Direct genetic trend was significant only for birth weight (P<0.01). Phenotypic trends were significant for all traits (P<0.01).

The aim of this study was to compare chemical composition, tannin content, in vitro gas production kinetics, in vitro dry matter and NDF digestibility and microbial biomass production of dried and ensiled pomegranate peel (PP; in four replicates). The crude protein, crude ash, neutral detergent fiber and acid detergent fiber in ensiled pomegranate peel (51, 48.4, 292.9 and 173.7, g/kg DM, respectively) were higher than the dried one(36.5, 37.5, 221.9 and 150.2 g/kg DM, respectively; P<0.05), whereas non-fiber carbohydrates (580 VS. 688.9 g kg- DM) were lower in pomegranate peel silages (P<0.05). Ensiling decreased the total phenolics (191.17 VS. 255.3 g of tannic acid equivalents kg-1 DM), total tannins (162.4 VS.219 g of tannic acid equivalents kg-1 DM) and non-tannin phenols (29.3 VS. 36.2 g of tannic acid equivalents kg-1 DM), pH (3.69 vs. 3.92) and water soluble carbohydrates (24.6 vs. 34.5), but increased the buffering capacity (12.73 vs. 8.79 meq-1 L), ammonia concentration (97 vs. 52 g kg-1 total N) and lactic acid (42.7 vs. 0.162 g kg-1DM) in pomegranate peel (P<0.05). The gas production, metabolizable energy and short chain fatty acids concentration (0.723 vs. 1.023 mmol) in dried PP were higher than those of ensiled PP (P<0.05). The in vitro fiber digestibility, partitioning factor, microbial biomass production, efficiency of microbial biomass production and ruminal ammonia concentration were higher in pomegranate peel (P<0.05). Although ensiling to some extent decreased phenolic contents, but did not improve the nutritive value of PP in comparison with drying.

To evaluate the chemical composition, degradability parameters and gas production parameters of barley grain, four latest-introduced linebred cultivars including Khoram, Mahur, Yusef and Sahra as well as a native one were used. Gas production parameters were determined by gas production technique, and dry matter degradability parameters by nylon bags. Gas production parameters were measured by four replicates at 2 until 96 h after incubation, and degradability parameters were measured by four replicates per fistulated sheep. There were significant differences in terms of dry matter, crude protein and crude fat contents between linebred and native barley grains (P<0.05). Furthermore, significant differences were observed among linebred grains in terms of crude protein and fat (P<0.05). There were no significant differences in gas production parameters among groups except of Yusef cultivar, where the lowest and highest potentials were in native and Yusef cultivar (300.1 vs. 281.7 ml/kg DM, respectively). The native cultivar has the highest metabolizable energy 8.71 MJ/kg), net lactation energy (5.24 MJ/kg), organic matter digestibility (57.67%) and short chain fatty acid (1.07 mmol) as compared to linebred cultivars. Degradability parameters showed the highest and lowest potential in Yusef and native cultivars (88.86 vs. 81.44 percent/h). Generally, results indicated that there were some differences among examined barley grain cultivars in terms of chemical composition and some degradability and gas production parameters.