Estrus cycle is a rhythmic change that occur in the reproductive system of females starting from one estrus phase to another. The normal duration of estrus cycle is 21 days in cow, sow, and mare, 17 days in ewe, and 20 days in doe. The species which exhibit a single estrus cycle are known as monstrous and species which come into estrus twice or more are termed polyestrous animals. Among them some species have estrus cycles in a particular season and defined as seasonal polyestrous. It includes goats, sheep, and horses. On the other hand, cattle undergo estrus throughout the year. The estrus inducers can grossly be divided into two parts, that is, non-hormonal and hormonal. Non-hormonal treatments include plant-derived heat inducers, mineral supplementation, uterine and ovarian massage, and use of Lugol's iodine. The hormones that are used in estrus induction are estrogen, progesterone, GnRH, prostaglandin, insulin, and antiprolactin-based treatment. Synchronization can shorten the breeding period to less than 5 days, instead of females being bred over a 21-day period, depending on the treatment regimen. The combination of GnRH with the prostaglandin F2α (PGF2α)-and progesterone [1, 2]-based synchronization program has shown a novel direction in the estrus synchronization of cattle with the follicular development manipulation.

Acute Phase Proteins are blood proteins primarily synthesized by hepatocytes as part of the acute phase response (APR). APR to disease is accompanied by an increase in the circulating concentration of a number of plasma proteins which are collectively known as the Acute Phase Proteins. According to the concentration, APPs are classified in positive APP, if they increase or negative APP, if they decrease. During mastitis, APPs move from the systemic circulation to mammary gland or there could be de-novo synthesis of the APP within mammary gland tissues. Among the APPs, Serum Amyloid A (SAA), Haptoglobin (Hp), Alpha 1-acid glycoprotein and Lipopolysaccharide binding protein play a major role during mastitis in cattle and their concentration will increase with the severity of the infection, inflammation or trauma. SAA is involved in defense against Gram positive and Gram negative pathogens. SAA acts by modulating innate immune system and by acting as an opsonin. Among the SAA isoforms, mammary associated SAA3 (m-SAA3) is important. The blood concentration of SAA and Hp increases dramatically after LPS infusion, with SAA (acute and middle phase of APR) appearing before Hp (Late phase of APR). The herd level APP might be useful for determining the prevalence of clinical and subclinical infections indicated by the high serum concentration of selected APP and by serving as the prognostic tool. APPs, used as markers of animal health may possibly be influenced by environmental factors, handling procedures and other types of stress in the absence of disease.

Leptin and IGF-1 plays a significant role in milk production and lactation in bovines. The present investigation was carried out to identify the novel polymorphisms in exon 3 region of leptin gene and exon 3 + partial intron 3 of IGF-1 gene and to analyze their association with the milk production performance in indicine and taurine crossbred (Karan Fries) cows. Blood samples were collected from 160 apparently healthy Karan Fries cows. Four SNPs at positions rs29004508 (C>T), rs29004509 (C>T), rs29004510 (T>C), rs29004511 (T>C) in Leptin gene and two SNPs at positions rs133251968 (C>A), rs137289661(C>T) in IGF-1 gene were found in Karan Fries cows, however rs29004509 (C>T) had positive correlation (p<0.05) with milk yield.The genetic variants observed in exon 3 region of leptin gene and their association with milk yield traits revealed the importance of CT genotype, which had been useful for genetic improvement of Karan Fries cow for milk production traits and can also be utilized as a potential genetic marker to select appropriate animals.

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This review analyses the use of molecular techniques in rumen microbial identification. The use of regular methods like roll tube and most probable number resulted in under estimation of rumen microbial growth. So molecular biology acts as an advanced tool for rumen microbial culture and identification of various new species. These techniques give complete descriptions of individual ruminal populations. Use of molecular techniques like PCR, DDGE and FISH, which also pave pathway for genetic manipulation of rumen microbes in the field of rumen manipulation. So the combination of traditional and molecular assays gives accurate and satisfactory results.