Lugo LS, Hernández CJ, López LL

Language: English/Spanish
References: 17
Page: 95-98
PDF size: 44.75 Kb.

ABSTRACT

The objective of this study was to evaluate the corpus luteum function developed from the ovulation of a persistent dominant follicle in Holstein heifers pretreated with a controlled internal drug release-bovine device (CIDR-B) in the absence of a corpus luteum. Twenty four heifers were treated with 25 mg of prostaglandin F2a (PGF2a) intramuscularly (im). Eleven days later, twelve of these heifers were fitted with a CIDR-B (Group 1; CIDR-B plus corpus luteum). The rest of the heifers (n=12) were fitted with a CIDR-B and received 25 mg PGF2a im (Group 2; CIDR-B, without corpus luteum). In both groups the CIDR-B were fitted without estrogens and remained in place for 12 days. Follicular development was assessed by transrectal ultrasonography. Two heifers from Group 1 (16.6%) and 8 from Group 2 (66.6%; P‹0.05) presented a persistent dominant follicle which ovulated upon removal of the intravaginal device. In the other heifers a different follicle ovulated. Blood samples were collected daily to measure the concentrations of progesterone on 7 animals from Group 1 that ovulated a different follicle, and 7 from Group 2 that ovulated a persistent dominant one. Sampling started on day 1 (day of standing estrus), and continued until day 16. There were no differences (P›0.05) in progesterone concentrations between groups. It is concluded that there was no evidence that the corpus luteum, which developed from the ovulation of a persistent dominant follicle in heifers treated with a CIDR-B and in absence of a corpus luteum, has an impaired function.

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