کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8426160 1546050 2018 4 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Influence of GnRH supplementation at CIDR removal on estrus expression and interval to estrus in beef cattle
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم کشاورزی و بیولوژیک علوم دامی و جانورشناسی
پیش نمایش صفحه اول مقاله
Influence of GnRH supplementation at CIDR removal on estrus expression and interval to estrus in beef cattle
چکیده انگلیسی
Previous research has indicated that multiple small doses of GnRH following CIDR removal increased circulating concentrations of estradiol. Therefore, our objective was to determine if a single small dose of GnRH (5 μg or 10 μg) at CIDR removal would impact expression of estrus and/or interval to estrus. Beef cows and heifers (n = 1620; n = 1057 cows, n = 563 heifers) were synchronized using the 7-day CO-Synch + CIDR protocol, and randomly assigned to one of three treatments (0, 5, or 10 μg of a GnRH analog at CIDR removal). Animals were inseminated following detection in estrus. Interval to estrus was calculated for each animal that exhibited estrus (INTERVAL 1). Animals that did not exhibit estrus were administered 100 μg of GnRH at the time of AI and their interval to estrus was designated at 120 h (INTERVAL 2). There was a treatment by age interaction (P = 0.05) on INTERVAL 1. Heifers treated with 5 μg of GnRH tended to have a shorter interval to estrus (P = 0.07; 47 ± 1.4 h) compared to 0 μg (50 ± 1.5 h) and did have a shorter interval compared to 10 μg (P < 0.01; 52 ± 1.5 h). There were no differences between treatments in interval to estrus among cows (P > 0.34). When animals that did not exhibit estrus by 120 h were included in the analysis there was no treatment by age interaction (P = 0.49). This is likely due to the fact that treatment (P < 0.01), but not age (P = 0.96) or treatment by age (P = 0.74) influenced expression of estrus. In addition, there tended to be a treatment by estrus interaction (P = 0.08) on pregnancy success. There was no difference in pregnancy success between treatments among animals that exhibited estrus (P > 0.30). In summary, 5 μg of GnRH at CIDR removal tended to decrease the interval to estrus and increased expression of estrus among heifers but not cows, and 10 μg of GnRH at CIDR removal did not improve estrus expression and lengthened the interval to estrus in comparison to the control.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Theriogenology - Volume 119, 1 October 2018, Pages 76-79
نویسندگان
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