Effects of equine chorionic gonadotropin dosage and its splitting in different days on reproductive performance of Nellore cows synchronized for timed-artificial insemination

This study evaluated the effects of dose of equine chorionic gonadotropin (eCG) and its splitting in different days of the synchronization protocol on reproductive performance of primiparous and multiparous Nellore cows. In the present study, 2,536 Nellore cows (1,634 primiparous and 902 multiparous) were assigned to receive in a 2 × 2 factorial design 1) an intravaginal progesterone (P4) device and 2.0 mg of estradiol benzoate (EB) on day -11, 12.5 mg (i.m.) of dinoprost tromethamine (PGF), 300 IU (i.m.) of eCG, 0.6 mg (i.m.) of estradiol cypionate (ECP), and P4 device withdrawal on day -2, followed by TAI on day 0 (n = 632 cows, being 409 primiparous and 223 multiparous; 300-2), 2) 300 IU (i.m) of eCG administered on days -4 and -2 (150 IU of eCG/day; n = 637 cows, being 412 primiparous and 225 multiparous; 300-4-2), 3) 400 IU (i.m.) of eCG administered on day -2 (n = 633 cows, being 406 primiparous and 227 multiparous; 400-2), and 4) 400 IU (i.m) of eCG administered on days -4 and -2 (200 IU of eCG/day; n = 634 cows, being 407 primiparous and 227 multiparous; 400-4-2). Individual cow BCS was assessed on days -11, 0 (timed-AI), and 31 of the study. Body condition score of the animals was classified into LOW or HIGH using the threshold of 2.75 (≤2.75 = LOW; >2.75 = HIGH). For primiparous cows, an eCG splitting effect was observed on follicle size, as cows receiving eCG on days -4 and -2 of the synchronization protocol had a larger follicle than cows administered eCG only on day -2. For day 31 P/AI, primiparous cows receiving 400-4-2, regardless of BCS, had a greater P/AI than cows from other treatments. Administering 400-4-2 to LOW BCS cows also resulted in greater P/AI than all other treatments assigned to LOW BCS cows. For multiparous cows, no treatment effect was observed for follicle size, estrus expression, and day 31 P/AI (P ≥ 0.21). In summary, increasing the dose and splitting the dose of eCG positively impacted the pregnancy rates of primiparous cows under a BCS ≤2.75, but no effects were detected on multiparous cows.

Single-step purification of equine chorionic gonadotrophin directly from plasma using affinity chromatography

Equine chorionic gonadotrophin (eCG) is a hormone widely used in superovulation protocols because of its follicle-stimulating action, which increases reproductive efficiency in animals of productive interest. It contains 45% carbohydrate, 10% of which is N-acetylneuraminic acid (sialic acid). The eCG purification procedures from equine serum or plasma are mainly based on chromatographic methods. However, before these procedures, it is necessary to follow sample pre-conditioning steps, such as several precipitation stages and/or ultrafiltration/diafiltration processes. In this work, an efficient affinity chromatographic matrix for eCG purification directly from plasma was developed. The matrix consisted of chitosan mini-spheres with immobilized wheat germ agglutinin (WGA). The matrix allowed 98% adsorption of eCG directly from plasma without any pre-treatment with an overall yield of around 60%. The matrix chosen was able to maintain the efficient performance of the purification process for three consecutive cycles. Also, the process was scaled-up 500 times in volume and tested over seven consecutive cycles maintaining its chromatographic performance. The results presented here suggest the potential application of this matrix to one-step purification of eCG from plasma.

FSH and eCG impact follicles development and expression of ovarian FSHR and caspase-9 in mice

The study aimed to investigate the effects of FSH and eCG on the ovarian and follicular development, expression levels of FSHR and caspase-9 of ovaries in vivo. One hundred and five prepuberty mice were allocated into FSH-1, FSH-2, FSH-3, eCG-1, eCG-2, eCG-3 groups and control group (CG). Mice in FSH-1, FSH-2 and FSH-3 were intramuscularly injected with 5, 10 and 20 IU FSH twice (on day 0 and 4), respectively. Mice in eCG-1, eCG-2 and eCG-3 were intraperitoneally injected with 10, 20 and 40 IU eCG on day 0 and 4. Mice in the CG were injected with 0.5 ml normal saline on day 0 and 4. Left and right ovaries of each mouse were dissected aseptically on days 7, 14 and 21, respectively. The results showed that on days 14 and 21 the ovarian sizes and follicle numbers of FSH-3 and eCG-3 groups were greater than CG (P<0.05). FSHR mRNA of FSH-2 and eCG-1 were higher than CG on days 14 and 21 (P<0.05). FSHR proteins of FSH-3 were higher than CG on days 14 and 21 (P<0.05). Caspase-9 mRNA in FSH and eCG groups was less than CG. There were positive correlations between follicle numbers and FSH and eCG doses. FSHR protein expressions had positive correlations between ovarian weights and sizes of ovary and follicle numbers (r=0.971, P<0.05) in FSH-treated mice. Serum FSH concentrations of FSH-2, FSH-3, eCG-2 and eCG-3 groups were greater than that of CG. In conclusion, eCG and FSH promoted the ovarian development, follicle genesis, FSH secretion, FSHR mRNA and protein expressions in ovaries of mice. FSH and eCG inhibited the expression of ovarian caspase-9 mRNA.