“…The changes in the uterine luminal fluid proteins (ULFP) appear to be necessary act as protease inhibitors (Fazleabas et al, 1982) [10] enzymes (Hansen et al, 1985) [21] carrier molecules for hormone, vitamin, and mineral (Zavy et al, 1979: Buchi et al, 1982: Pentacost and Tang, 1987 [43,7,34] pregnancy recognition signalling molecules (Godkin et al, 1984;Bartol et al, 1985;Godkin et al, 1988) [17,34,18] immunoregulatory molecules (Murray et al, 1978) [31] as well as several more likely unidentified roles. Some ULFPs are synthesized from the uterine endometrium, while the majority are sequestered from the blood into the uterine lumen (Fischer and Beier, 1986) [11] . The significant variations in the ULFPs have been seen in mares during the estrous cycle (Zavy et al, 1978;Zavy et al, 1979) [43,44] , pigs (Kayser et al, 2006) [25] , buffaloes (Kumar and Purohit, 2018) [26] , cows (Alavi-Shoushtari et al, 2006; Alavi-Shoushtari et al, 2014) [3,2] .…”