مجله تولیدات دامی
سال هجدهم شماره 1 (بهار 1395)

Genomic Selection (GS) is a tool for prediction of breeding values for quantitative traits. For a successful application of GS, accuracy of predicted genomic breeding value (GEBV) is a key issue to consider. Here we investigated the accuracy of GEBV in 345 genotyped Iranian Holstein cattle. The study was performed on milk, fat, protein yield and somatic cell count. Four methods G-BLUP, Bayes B, Reproducing kernel Hilbert Spaces (RKHS) and Neural Networks (NN) were used to predict genomic breeding values and their accuracies. The GEBV accuracies varied between 0.39 for somatic cell count to 0.73 for fat yield. Bayes B gave the highest accuracies among methods. Bayes B and non- parametric methods tended to produce inflated predictions ( slope of the regression of GBV on EBV greater than 1). However, in all traits, lower estimates of MSE were obtained using G- BLUP. Bayes B regression model are of interest for future applications of genomic selection in this population, but further improvements are needed to reduce deflation of their predictions.

In order to compare the precision of predictions of NRC (2001) and CNCPS models, 17 Holstein fresh cows were assigned in a randomized complete block design to a balanced diet with NRC (2001) and CNCPS software. The predicted DMI, energy allowable milk and protein allowable milk by both models were compared with observed values. The precision of the predictions of models was evaluated by calculation of R2, mean bias and root mean square prediction error (RMSPE). Both models predicted DMI lower than the observed values (P  0.01). The mean bias, RMSPE and R2 were 2.22, 2.84 and 0.48 for NRC (2001) and 3.18, 3.99 and 0.52 for CNCPS, respectively and CNCPS predicted the DMI 20% lower than the observed value. The observed milk production was 29.78 kg/d. predicted energy allowable milk by NRC (2001) and CNCPS were 25.68 and 22.32 kg/d, respectively. Predicted protein allowable milk with NRC (2001) and CNCPS were 25.80 and 28.37 kg/d, respectively and NRC (2001) predicted the milk production 14 % lower than observed value. Given the importance of DMI in fresh cows seems NRC (2001) has more precision compared to CNCPS for estimating nutritional requirements.

Effect of GLOBACID® acidifier in different stocking densities on performance and blood metabolites was examined using 576 one-day broiler chickens Ross 308 in a completely randomized design with 6 treatments and four replications for each treatment through a (3×2) factorial arrangement with three levels of stocking densities (14, 16 and 18 chicks per square meter) and two levels of GLOBACID® acidifier (zero and one kg per each ton of feed). The lowest feed intake was seen in 18 stoking density treatment which fed one kg of acidifier in the ration and this treatment was significantly different with other treatments (P

Two independent experiments were conducted to evaluate the nutritional value of Purslane powder and determinate its effects on performance, egg quality and reproductive system parameters of laying hens. One hundred and twenty laying hens (Leghorn, Hy-Line W-36) were used in a completely randomized design with 4 treatments and five replicates. Hens received diet supplemented with different levels of Purslane powder (0, 1, 2 and 3 percent) for 8 weeks. The results of these expriments showed that gross energy, crude protein, ether extract and crude fiber contents of Purslane samples were 2921.67(Kcal/Kg DM), 22.28 (%), 3.99 (%) and 9.47 (%) of DM, respectively. The AME and TME values of Purslane powder were 1864.70 and 1956.08 Kcal/Kg DM, respectively. Performance parameters of the laying hens were not affected by inclusion different levels of dietary Purslane powder in the diet. Shell strength, shell thickness, egg yolk color, ovary and oviduct weights, the number of large yellow follicles and the weight of largest follicle showed significant increase (P

This study was conducted in order to investigate the effect of Mentha piperita (PP) and Melissa officinalis (MP) powder on performance, apparent digestibility of fat and protein, and blood parameters of broiler chicks subjected to heat stress. Two hundred day-old male Ross broiler chicks were assigned to a completely randomized design with 5 dietary treatments and 4 replicates. The experimental treatments consisted of: 1) control group (without feed additive), 2) group supplemented with 0.5% PP, 3) group supplemented with 1% PP, 4) group supplemented with 0.2% MP and 5) group supplemented with 0.4% MP. The experimental diets were offered to the chicks from 25 to 42 day of age. During the experiment, the birds were kept at 34°C±2 for 8 hours (9.00 to 17.00). The effect of Mentha piperita and Melissa officinalis powder was not significant on feed intake but more body weight gain (BWG) and less feed conversion ratio (FCR) observed in the birds fed diet supplemented with 1% of PP. The apparent digestibility of dry matter and crude fat were not affected by the treatments, but the digestibility of protein was increased (P0.05). The results of this experiment showed that dietary addition of PP at the level of 1% for broilers exposed to heat stress could possibly act as a growth promoter via improving weight gain and digestibility of protein.

This experiment was conducted to evaluate the effect of silver nanoparticles coated on clinoptilolite on performance traits, liver enzymes and blood lipid concentrations to use 375 Cobb 500 broiler chickens in completely randomized design with 5 treatments and 5 replicates and 15 birds to each replicate. The use of silver nanoparticles coated on clinoptilolite improved feed conversion ratio compared with the control treatment (P0.05). The use of silver nanoparticles coated on clinoptilolite decreased alkaline phosphatase and alanine amino transferase level in serum (P0.05). In conclusion, the results of this study showed that silver nanoparticles coated on clinoptilolite can be considered as a growth and health promoters as well as according to the results of liver function enzymes and blood lipids prevent liver damages during rearing period in broiler chickens.

This study aimed to investigate the effect of different concentration of zinc nano-complex on bull spermatozoa quality and percentage of pregnancy after freeze-thawing process. Ejaculates were collected from four Holstein bulls, twice a week during four weeks. semen samples diluted with Bioxcell extender containing 0 (Control), 10-6 nM, 10-5 nM,10-4 nM, 10-3 nM, and 10-2 nM of zinc nano-complex. then, were freezed and thawed after 72 hours. Motility of sperm was analyzed with computer assisted sperm analysis. the highest and lowest concentrations of zinc nano-complex along with control group were analyzed for the DNA fragmentation, malondialdehyde (MDA) concentration, mitochondrial activity, and pregnancy outcomes. The proportion of the total and progressive motile spermatozoa and the percentage of spermatozoa with fragmented DNA was not different among the groups. . However, the groups containing 10-2 nM and 10-6 nM zinc nano-complex had a lower level of MDA concentration and higher activity of mitochondria. Moreover, the pregnancy outcome was not affected by the treatment with zinc nano-complex. In conclusion, our data revealed that supplementation of bull semen Bioxcell extender with zinc nano-complex can decrease the level of MDA and improve mitochondrial activity, although such an improvement was not reflected in results of fertility rates.

The aim of the current study was to evaluate the effects of the guanidinoacetic acid (GAA) supplement on the semen freezability of broiler breeder roosters. Experiments were performed with twenty Ross commercial strain broiler breeder roosters in four treatments and five repeats in a complete randomized design. Roosters were fed a diet containing 0% (control), 0.06%, 0.12% and 0.18% GAA supplement for eight weeks. Semen samples were collected weekly by abdominal massage. In order to equilibrate the temperature, semen samples were diluted with an extender and placed inside the refrigerator at 5 ° C. Samples were then packed into straws, exposed to nitrogen vapor and finally moved into liquid nitrogen containers. After freezing-thawing, the total and progressive motility, viability, morphology and membrane integrity of spermatozoa were assessed. The mean of total motility at the 0.12% and 0.18% levels were significantly higher than that of other groups (05/0>P).

The aim of this current study was using of a management and feeding program in order to improving of reproductive factors performance in one hundred head ewes with Iran Black bred. Ewes were placed in two A (75 head) and B (25 head) groups. Ewes of A group were milk-cutted and were introduced to rams 80 and 90 days after parturition respectively. Forty days before introduction to rams, melatonin implant was laid under skins of these ewes. 75 ewes of A group were kept separately in three groups of 25th and were fed by high starch diets complemented with saturated fatty (control treatment), extrude cotton seed (omega 3 treatment) and full fat soybean (omega 6 treatment). B group’s ewes were milk-cutted and introduced to rams 120 and 180 days after parturition and were fed the same as control treatment diet. Estrus, ovulation, lambing and twining rates were counted and recorded in various experimental treatment. The weight of lambs were measured in time of birth, 3th and 4th month. Lambing and twining rates was higher in omega 3 and omega 6 treatment than control treatment and B group. Lamb weight average in their 3 and 4 month old was significant higher in B group than all treatment of A group. Generally, results of this study showed that using of management program of A group along with omega 3 and 6 feeding could improve reproductive factor performance.