Abstract

LOPEZ-GARCIA, Susana et al. Estrus synchronization in ewes with a six-day protocol using new, second-use, third-use and fourth-use CIDR devices. Rev. mex. de cienc. pecuarias [online]. 2023, vol.14, n.3, pp.610-621.  Epub Sep 08, 2023. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v14i3.6309.

Estrus synchronization( is a vital strategy in sheep production and is accomplished most often via controlled internal drug release (CIDR) devices. Reuse of CIDR devices can reduce operating costs and ewe exposure to progesterone (P4), but remains controversial. A comparison was made of the effects of new and reused natural progesterone-releasing intravaginal (CIDR) devices in six-day protocols on reproductive performance variables and blood serum progesterone concentrations in multiparous ewes. A total of 172 sheep (average body weight = 59 kg) were randomly distributed into four treatments: CIDR1 (control group, new devices), CIDR2 (second-use), CIDR3 (third-use) and CIDR4 (fourth-use). The variables ewes in estrus, pregnancy rate, fertility rate and parturition type did not differ (P>0.05) between treatments. Estrus onset was later (P≤0.05) in CIDR1 (40 ± 10 h) than in CIDR2 (31 ± 9 h). Ewes in estrus ranged from 93 to 100 %, average pregnancy rate was 80.8 %, average fertility rate was 80.2 % and the prolificacy index was 1.26. The single delivery rate was higher (P≤0.05) than the double delivery rate in all four treatments. Intravaginal CIDR devices can be used in ewes up to four times in six-day estrus synchronization protocols without affecting reproductive variables.

Keywords : CIDR reuse; Sheep; Reproductive variables.

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