Lutalyse sterile solution

The estrous cycle of all cows was synchronized with 2 intramuscular injections of 25 mg of PGF 2α (5 mL of Lutalyse sterile solution, 5 mg/mL of dinoprost as tromethamine salt, Zoetis, Florham Park, NJ) given 14 d apart, at 38 ± 3 and 52 ± 3 DIM. After the second injection of PGF 2α , which was considered the end of the voluntary waiting period, the tailheads of cows were painted with chalk daily, and removal of chalk was used as an indicator of estrus. Cows detected in estrus were inseminated on the same day, in the morning. Cows not inseminated by 63 ± 3 DIM were enrolled in the Ovsynch program. The timed AI protocol consisted of an intramuscular injection of 100 μg of GnRH (2 mL of Cystorelin, gonadorelin diacetate tetrahydrate equivalent to 43 μg of gonadorelin/mL, Merial Ltd., Duluth, GA) on d 63 ± 3 postpartum, followed by an injection of PGF 2α 7 d later, and a second injection of GnRH 56 h after the PGF 2α treatment, at 72 ± 3 DIM. Cows were inseminated approximately 16 h after the second injection of GnRH, on d 73 ± 3 postpartum. Cows that returned to estrus were reinseminated on the same day and considered nonpregnant to the previous AI. Cows diagnosed as nonpregnant at the pregnancy exam had the estrous cycle resynchronized with the Ovsynch protocol and were reinseminated within 10 d of nonpregnancy diagnosis.

Estrous cycles were synchronized (Figure 1) starting at 40 ± 3 DIM with an i.m. injection of 25 mg of PGF 2α (dinoprost tromethamine; Lutalyse sterile solution, Zoetis, Florham Park, NJ) followed by an i.m. injection of 100 μg of GnRH (gonadorelin hydrochloride; Factrel, Zoetis) administered 2 d later, at 42 DIM. Seven days later, at 49 DIM, cows received a GnRH injection, and Treatments represent the ratio between n-6 and n-3 fatty acids in the diet. R4 is a ratio of 3.9 parts of n-6 to 1 part of n-3; R5 is a ratio of 4.9 parts of n-6 to 1 part of n-3; R6 is a ratio of 5.9 parts of n-6 to 1 part of n-3. then 12 h after the GnRH a controlled internal drugrelease (CIDR; Eazi-Breed CIDR, Zoetis) insert containing 1.38 g of progesterone for intravaginal use. The CIDR insert was kept for 6.5 d, until 56 DIM. One hour after the CIDR removal, cows received an i.m. injection of PGF 2α followed by another injection of PGF 2α 24 h later. A GnRH injection was administered at 58 DIM to induce ovulation and this day was considered d 0 of the estrous cycle, which was confirmed by ultrasonography based on disappearance of a preovulatory follicle within 48 h of treatment. Cows that did not ovulate to the final GnRH were re-enrolled in the same protocol for synchronization of the estrous cycle.