SALIVARY MUCIN PROFILING IN RELATION TO OESTRUS AND EARLY PREGNANCY IN DAIRY CATTLE
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Date
2021
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Publisher
ICAR-SRS-NDRI, KARNAL
Abstract
Accurate detection of oestrus and diagnosis of early pregnancy in dairy cattle
still remains as a challenge, especially in field conditions. With the aim to identify
potential method/tool for identification of oestrus and early pregnancy, the present
study assessed salivary crystallization pattern in cows during the oestrus cycle and
early pregnancy and also carried out global proteomic analysis of salivary proteins.
Saliva was collected from a total of 15 Holstein Friesian crossbred cows during
oestrous cycle and during early pregnancy. Salivary crystallization patterns were
assessed using microscopy and proteomic profiling was done using a highthroughput
LC-MS/MS-based method. At least 6 types of salivary crystallization
patterns were discerned that include Fern-like, Branch-like, Fir-like, Branch like + Fir
like, Fir like + Fern like, and Branch like + Fern like. Typical fern pattern is observed
on the day of oestrus only, therefore it could be used as a tool for oestrus detection.
The absence of a typical fern pattern in saliva on days 20-22 after breeding could be
considered as an indication of pregnancy. Regarding proteomic analysis, a total of
3707 proteins were detected in the saliva of crossbred cows. A total of 2463, 1456,
2453 and 1574 non-redundant proteins were identified on the day of oestrus, day 9
of dioestrus, day 16 of pregnancy, and day 18 of pregnancy. A total of 549, 161, 486,
and 197 proteins were specific to oestrus, dioestrus, day 16 of pregnancy, and day
18 of pregnancy. The presence of oestrus specific salivary proteins like 17-β
hydroxysteroid dehydrogenase, Inhibin beta A chain, Heat shock 70kDa protein 1A,
and, Alpha enolase have the potential to be used to identify oestrus in cattle. Most of
the proteins specific to oestrus were involved in the metabolic process and the rest
of them were involved in estrogen signaling, steroid biosynthesis pathways.
Pregnancy-related proteins like Pregnancy Associated Glycoprotein, Gametocytespecific
factor 1 like protein, Placental protein-9, Chorionic somatomammotropins
hormone 2, and Interferon-tau were detected in the saliva of crossbred cows during
early pregnancy, indicating that saliva could be used as a non-invasive method for
early pregnancy diagnosis. Major pathways and protein-protein interaction found to
be represented by the pregnant animal saliva proteins was the notch signaling
pathway, hippo signaling pathway, p53 signaling pathway, phagosome, JAK-STAT
cascade, etc. The study also identified few salivary mucins specific to oestrus that
need to be validated on large number of cows before arriving at a conclusion on their
usage for oestrus detection in cows.