The aim of this study was to evaluate the effect of different durations of flaxseed oil consumption on broiler performance, fatty acid content of meat and expression of FADS2 gene in the liver of chicken. A total of 336 unsexed day old chicks were randomly assigned to 7 dietary treatments with 4 replicates of 12 chickens in each. Body weight, weight gain, feed intake and feed conversion ratio were not affected by dietary treatments. Longer consumption of flaxseed oil resulted in higher deposition of long chain n‐3 fatty acids in broiler breast and thigh (P < 0.05). Regression analysis showed that feeding broilers with diet enriched with flaxseed oil 17 and 7 days prior to slaughter for breast and thigh respectively, is enough for producing n‐3 labeled meat. Weekly replacement of oil source of diet (soybean oil) with flaxseed oil increased expression of FADS2 gene. To incorporate enough n‐3 fatty acids into chicken meat through addition of flaxseed oil to broiler diet and to maximize de novo long chain n‐3 fatty acid synthesis in broiler body, we recommend adding flaxseed oil to broiler diets 17 days prior to slaughter. Practical applications: Omega‐3 enrichment of broiler chickens depends on both nutrition and gene expression. Flaxseed oil is an omega‐3 oil source that can be supplemented to broiler diet to enrich chicken meat with the beneficial n‐3 fatty acids. However, adding such oil sources to broiler rations is restricted because of their negative effects on broiler performance and meat quality. Therefore, shorter period of such oil sources consumption is preferred. Flaxseed oil consumption can affect gene expression too. Thus, it is necessary to determine the optimum duration of flaxseed oil supplementation to broiler diets to produce omega‐3 labeled chicken using both nutrition and gene expression. Flaxseed oil consumption can affect fatty acid profile of chicken meat through manipulation of fatty acid deposition, de novo fatty acid synthesis, fatty acid oxidation and expression of genes involved in fatty acid metabolism. To incorporate enough n‐3 fatty acids into chicken, providing at least 3 g n‐3 fatty acid per kilogram of meat, by adding flaxseed oil to broiler diet, we recommend adding flaxseed oil to broiler diets 17 days prior to slaughter.

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An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro-organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.

This study was carried out to investigate genetic diversity in Mazandaranian native cattle population comparised to the Holstein breed, using Inter Simple Sequence Repeats (ISSR) marker. A total of 175 animals, including 71 native and 104 cattle of Holstein breed were screened. The extraction of DNA samples were carried out, using modified salting out method. A 19-mer oligonucleotide, (GA)9C, was used as primer in PCR reactions. The PCR products showed 15 different fragments with length ranged from 120 to 1600 bp in the two breeds.. Genetic variation indexes, including effective number of alleles, Shannon index, Nei's gene diversity and standard genetic distance were estimated, using POPGene software. Generally, the estimated genetic variation indexes showed low levels of diversity in the two breeds. However, Nei's gene diversity and Shannon index estimation was observed almost two folds in native cattle compared to Holstein breed. Less levels of diversity in Holstein cattle may be because of applying intensive selection programs. Conversely, native cattle have been less affected by selection. Therefore, it seems that Mazandaranian native cattle probably are better for breeding programs than Holstein cattle. Results showed that ISSR Markers are reliable and can be used in genetic diversity investigations.