Eazi breed cidr

Estrus synchronization of recipient cattle began 16 days prior to the embryo transfer with the use of an intravaginal progesterone releasing device (1.38 g; Eazi-Breed CIDR; Zoetis) and the administration of gonadorelin (100 mcg; Factrel; Zoetis) done on day 0. On day 7, the CIDR was removed and prostaglandin (25 mg; Lutalyse; Zoetis) was administered. A second dose of gonadorelin (100 mcg; Factrel; Zoetis) was given on day 9 and recipients were monitored for signs of estrus. Confirmation of recipient synchronization was done on day 15 via corpus luteum detection using a transrectal ultrasound. On day 16, embryo transfers were performed. Recipients received a caudal epidural of 100 mg 2% lidocaine (Xylocaine; Fresenius) prior to embryo transfer. Two to three blastocysts were loaded into 0.25 cc straws and transferred using the non-surgical transcervical technique into the uterine horn ipsilateral to the corpus luteum. On day 35 of gestation, transrectal ultrasonography (5.0 MHz linear probe; EVO Ibex, E.I. Medical Imaging) was done to confirm pregnancies, and reconfirmed on day 80. A total of four embryo transfers were performed, and recipients were resynchronized for subsequent embryo transfers if they did not become pregnant from prior embryo transfers.

A total of 12 nulliparous cycling Holstein heifers were randomly assigned (six heifers per treatment) to one of two treatments:

4‐day CoSynch+CIDR (n = 6): The heifers received an intravaginal CIDR insert (Eazi‐Breed CIDR^®, Zoetis Animal Health, Florham Park, NJ, USA) containing 1.38 g of progesterone for 4 days. On the day of CIDR insert removal, 25 mg of PGF_2α (5 mL Lutalyse ^® Zoetis Animal Health) was injected IM; 72 h after CIDR insert removal, the heifers received 100 μg of GnRH (2 mL Factrel^®, Zoetis Animal Health) IM and TAI (Fig. 1).

5‐day CoSynch+CIDR (n = 6): The heifers received an intravaginal CIDR insert containing 1.38 g of P₄ for 5 days. The heifers were administered 25 mg of PGF_2α IM at the time of CIDR insert removal, and 100 μg of GnRH IM and TAI 72 h after CIDR insert removal (Fig. 1).

From the time of arrival at Keeble farm, the ewes were managed as a single flock under commercial grazing conditions. For breeding, ewes were progesterone-synchronised by inserting a controlled release intravaginal device (Eazi-Breed CIDR^®, Zoetis New Zealand) on 13 March 2019 for a period of 12 days. Pregnancy diagnosis was undertaken twice in mid-pregnancy (4 June and 25 July) using trans-abdominal ultrasonography undertaken by a commercial operator to confirm pregnancy and foetus numbers. Single and twin-bearing ewes were retained while non-pregnant and triplet-bearing ewes were culled (n = 21).
On 30 July 2019, all ewes were weighed, body condition scored, and moved to a single paddock closer to the milking parlour with a pasture requirement according to commercial conditions for late pregnant ewes (pre-lambing). Forty-eight ewes were retained for lambing and the lambing period occurred between 13 August and 9 September 2019. On milking days (see below), lambs were separated from their dams for six hours between morning and afternoon milkings, during which time each lamb was bottle-fed 300 g of ewe’s milk [37 (link)]. If a ewe produced less than 1200 g/day of milk or abandoned their lamb/s, the lamb/s was/were removed from the ewe and fostered. These ewes, and ewes for whom all their lambs died (18), were excluded from the milking study.

Unless otherwise indicated, chemicals were purchased from Sigma–Aldrich (St. Louis, MO, United States). The Cryotop devices were purchased from Ingamed (Maringá, Paraná, Brazil). Follicle-Stimulating Hormone (FSH), Pregnant Mare Serum Gonadotropin (PMSG), and Prostaglandin (PG) were purchased from Sansheng biological technology (Ningbo, China); EAZI-BREED-CIDR and Holding medium were purchased from Zoetis (New Jersey, United States).

Unless otherwise indicated, chemicals were purchased from Sigma–Aldrich (St. Louis, MO, United States). The Cryotop devices were purchased from Ingamed (Maringá, Paraná, Brazil). Follicle-Stimulating Hormone (FSH), Pregnant Mare Serum Gonadotropin (PMSG), and Prostaglandin (PG) were purchased from Sansheng biological technology (Ningbo, China); EAZI-BREED-CIDR and Holding medium were purchased from Zoetis (New Jersey, United States).