نوع مقاله : مقاله پژوهشی
نویسنده
استادیار، گروه علوم دامی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران، صندوق پستی 578
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسنده [English]
The objective of this study was to compare the effect of five estrous synchronization protocols on ovulatory follicle diameter, progesterone concentration at AI and days 5 and 12 after AI and conception rate in Holstein cows during heat stress. Holstein cows (n=250) with more than 30 kg/d milk yield were randomly assigned to one of 5 experimental groups, 1) ovsynch (OV); 2) presynch-ovsynch (PO); 3) double ovsynch (DO); 4) G7G-ovsynch (G7G) and 5) PG7G-ovsynch (PG7G).Results showed that ovulatory follicle diameter was smaller in cows synchronized with OV protocol compared to other protocols (P˂0.05). Progesterone concentration at days 5 and 12 post AI was lower in OV protocol compared to other protocols (P˂0.05). Conception rates at days 32 and 62 post AI were lower in OV protocol compared to other protocols (P˂0.05).There was no difference among other synchronization protocols (P <0.05).In conclusion, results of present study showed that using presyhcnronization before initiation of Ovsynch can increase PR/AI of Holstein cows during heat stress.
کلیدواژهها [English]