Progesterone milk residues in goats treated with CIDR-G(®) inserts

Area of Science:

• Veterinary Medicine
• Reproductive Endocrinology
• Animal Science

Background:

• Progesterone (P4)-impregnated intravaginal controlled internal drug-releasing devices (CIDRs) are widely used for estrus synchronization in ruminants.
• CIDRs aim to synchronize the estrous cycle by maintaining treated animals in the luteal phase.

Purpose of the Study:

• To compare progesterone concentrations in milk from reproductively cycling goats, goats treated with CIDRs, and pregnant goats.
• To assess milk progesterone levels as an indicator of estrus synchronization efficacy and reproductive status.

Main Methods:

• Intravaginal CIDRs were inserted into treatment goats for 19 days.
• Milk samples were collected daily from control and CIDR-treated goats (days 0-21).
• Milk samples were collected from pregnant goats between days 40-60 of gestation.
• Milk progesterone concentrations were analyzed, and area under the curve (AUC) was calculated.

Main Results:

• No significant differences in AUC for milk P4 were observed between control (29.5 ± 11.9 d·ng/mL) and CIDR-treated goats (33.7 ± 6.6 d·ng/mL) (P = 0.77).
• Peak single-day milk P4 levels were comparable across control (4.8 ± 1.5 ng/mL), CIDR-treated (4.0 ± 1.0 ng/mL), and pregnant goats (6.0 ± 0.4 ng/mL) (P = 0.42).
• Highest 5-day average milk P4 concentrations were also similar among groups (control: 3.6 ± 1.3, CIDR-treated: 2.9 ± 1.8, pregnant: 4.2 ± 0.3 ng/mL) (P = 0.56).

Conclusions:

• Intravaginal P4 CIDR devices used for 19 days in healthy goats resulted in milk P4 levels comparable to or lower than those naturally produced during diestrus or pregnancy.
• Milk progesterone monitoring offers a potential non-invasive method for evaluating estrus synchronization protocols and reproductive status in goats.