The objective of this study was to determine if there are differences in luteal size (LS), progesterone (P4), and luteal blood flow (LBF) between pregnant and non-pregnant Bos indicus dairy cows during the first three weeks after insemination, and whether these parameters are related to each other. Lactating cows (n = 13) of mixed parity with a body weight of 430 ± 18 kg (mean ± SD), showing regular estrous cycle were used in the study. All cows were artificially inseminated and were classified as pregnant (embryonic heartbeat on day 30; n = 8) or non-pregnant (inter-estrus interval 17 to 21 days, n = 5). In order to compare the LS and LBF after artificial insemination, B-mode and color Doppler ultrasonography of ovaries were performed on days 4, 5, 6, 7 (first week), 8, 10, 12, 14, (second week), and 16, 17, 18, 19, 20, 21 (third week) in pregnant and non-pregnant cows. Results revealed that the mean LBF was consistently higher (P < 0.05) during days 7 through 21 in pregnant cows than in non-pregnant cows. The mean LS was higher (P < 0.05) on days 6 and 7, and from day 17 onwards, and the mean concentration of P4 was higher (P < 0.05) on days 19, 20, and 21 in pregnant cows. In conclusion, LBF is a more sensitive parameter than LS and P4 for detection of differences in luteal function between pregnant and non-pregnant Bos indicus dairy cows during the first three weeks after AI.

Extracellular vesicles (EVs) have been identified in the uterine fluid in different species and have been pointed as key players in the embryo-maternal dialogue, maternal recognition of pregnancy and establishment of pregnancy. However, little is known about the uterine EVs in the mare. Therefore, the present study aimed at characterizing EVs from uterine lavage of cyclic mares by comparing five EVs isolation methods and the combination of them: (1) ultracentrifugation (UC); (2) concentration of lavage volume by Centricon ultrafiltration (CE); (3) the use of CE with different washing steps (phosphate-buffered saline with or without trehalose); (4) size-exclusion chromatography with iZON-qEV columns, and (5) a combination of the methods with best results based on EVs yield, purity, and protein cargo profiles. Transmission electron microscopy and Western blotting confirmed the isolation of EVs by all methods but with quantitative and qualitative differences. Mass spectrometry provided differences in protein profiles between methods, number of identified proteins, and protein classes. Our results indicate that the combination of CE/trehalose/iZON/UC is an optimal method to isolate equine uterine EVs with good yield and purity that can be applied in future studies to determine the role of equine uterine EVs in embryo-maternal interactions.

Sahiwal cow is Bos indicus which is an important dairy breed of tropical and sub-tropical region. Research on reproduction is rare in this breed. The objectives of the present study were to determine the effect of Ovsynch (OVS) versus prostaglandin F (PG) protocol on estrus response and its intensity, ovulation rate, timing of ovulation and pregnancy per artificial insemination (AI) in Sahiwal cows. Experimental cows (n = 80) were of mixed parity, lactating, suckled, ≥120 days postpartum with body condition score 3.08 ± 0.34 and 375-475 kg of body weight which were randomly assigned to receive either OVS (n = 46) or PG (n =34) protocol. Cows were inseminated twice at 12 and 24 h after second gonadotropin releasing hormone in the OVS group, and 72 and 84 h after administration of prostaglandin F in PG group, respectively. The results revealed that estrus response did not differ (P > 0.05) and was 87% in OVS and 78% in PG cows. Ovulation rate did not differ (P > 0.05) and was 50% in both, OVS and PG cows. The pregnancy per AI did not differ (P > 0.05) and was 43% in OVS compared to 31% in PG cows. It is concluded that estrus response, ovulation rate and pregnancy per AI of OVS protocol is the same as PG in Sahiwal cows.

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