عنوان مقاله [English]
To determine the effects of garlic extract on egg yolk cholesterol, egg microbial load, and productivity of egg-laying chickens at different intervals, Spain made garlic extract, Garlic on brand was applied. As many as 392 egg-laying hens of Hi-line race and all 30 weeks old were randomly classified in separate but equal groups and for 6 weeks received seven types of drinking water mixed with different garlic extract concentrations and same nutrition ratio. The first treat was control treat so it only contained pure water. Second treat contained 0.01 % garlic extract and was supplied for two days. Other treats were respectively as follows; 0.02% for two days a week, 0.01% for four days a week, 0.02% for four days a week, 0.01 % for six days a week, and 0.02% for six days a week. Through out experiment, the flock was observed and quality of yolk cholesterol, blood serum, egg shell microbial load, egg contents, production percent, egg bulk, egg weight, FCR, and egg shell thickness were recorded. The information obtained during six weeks was statistically analyzed. At the end of third and seventh week and also one and two weeks following experiments, sampling was carried out. According to results, it was only at the end of sixth week that the mixture of garlic extract with drinking water significantly affected on cholesterol of control group and other garlic extract consumers (P<0.05). However, among other treats, significant difference was not observed. Regarding blood serum cholesterol, in spite of blood cholesterol reduction at the end of experiment, no significant difference was detected among treats (p< 0.05). Egg content and egg shell microbial load didnt show significant difference from control group (P> 0.05). At third week, egg shell thickness significantly reduced compared to control group in other treats (P<0.05). However, at the end of sixth week, no significant difference was noticed (p>0.05). Regarding egg bulk, production percent and FCR, there was no significant difference between treats (p >0.05). Finally, it can be concluded that garlic extract consumption could only increase yolk cholesterol up to 17% and didnt have any other impact on egg-laying hens. By the way, the most economic consumption of this extract is 0.01 % for two days.