INTRODUCTION Colostrum is the most effective natural immune booster that is known to science. The new born calves are fed with the initial mammary secretion, called bovine colostrum, which is produced within the first 72 hours of parturition. It contains several immunological and growth factors, essential nutrients, trypsin inhibitors, and protease inhibitors to prevent gastrointestinal tract deterioration (Das, 2009). According to Panahi et al. (2010), bovine colostrum is similar to human colostrum and are rich in vitamins, minerals, fats, carbohydrates, disease-fighting proteins, growth hormones, and digestive enzymes. Colostrum is known to be crucial for the development of the neonate immune system. The amount of lactoferrin in colostrum is 20-fold greater than it is present in the raw milk (Reiter, 1978). Bovine colostrum has a total immunoglobulin concentration that is around 100-folds higher than that of regular milk (McGrath, 2016). Age, breed, nutrition, and diseases are some of the variables that affect the composition and physical characteristics of an animal (Tsioulpas et al., 2007). Bovine colostrum was incorporated into cream separated to remove fat which in turn increased the concentration of protein. Separation technologies used to produce protein ingredients derived from milk include screening based on size differences viz. centrifugation based on density differences; membrane processes based on size differences, such as ultrafiltration, diafiltration, nanofiltration, and reverse osmosis (Huffman and Harper 1999). The deffated colostrum can also be used for the production of any value-added products. For determining the quality of colostrum, Fleenor and Stott (1980), firstly developed a regression equation to estimate colostral immunoglobulin concentration from the specific gravity of fresh whole colostrum (globulin concentration = 211.4 × (specific gravity - 218.2). The developed colostrometer, which incorporated the relationship between immunoglobulin concentration and the specific gravity into a conventional hydrometer. Although colostrometer readings had a stronger correlation with actual IgG levels, farmers do not frequently use it (Bartier et al., 2015). Vasseur et al. (2010) stated that even though producers were aware of the benefits of using a colostrometer, its utilization remains low, possibly due to its fragility and inconvenience of use. The present study was carried out to evaluate and compare the quality and physico-chemical parameters of colostrum samples collected from cow and buffalo. MATERIALS AND METHODS A. Preparation of colostrum The bovine colostrum of 1st and 2nd days after parturition obtained from the healthy cows and buffalos were procured from the Community Cattle Care Centre of College of Food and Dairy Technology, Koduveli and Livestock Farm Complex (LFC), Madhavaram of Tamil Nadu Veterinary and Animal Sciences University and private dairy farms, Chennai. Post procurement, the colostrum were immediately transferred to the sub – zero(-20°C) condition at deep freezer. The frozen colostrum was thawed indirectly using hot water and defatted using centrifugal cream separator (Mach, Coimbatore) before experimental trials. B. Colostrometer reading Colostrometer (Biogenics Laboratories, Mapleton, USA) was used to determine the quality and immunoglobulin content in colostrum. The colostrometer consists of a measuring cylinder, spindle, and a float, allowing conclusions about the specific gravity due to its displacement. The density correlates with the immunoglobulin concentration in the colostrum. Based on this correlation, the density measured with the colostrometer could conclude the immunoglobulin concentration as shown in the Table 1 (Fleenor and Slot 1980). C. Determination of physicochemical properties All the chemicals used in the present study were of analytical grade and procured from HiMedia Laboratories Private Ltd, Mumbai, India. The reagents required for analysis were freshly prepared from chemicals by adopting standard procedures and stored under desired conditions wherever required. The deffated bovine colostrum were analysed for physico-chemical properties such as fat, protein, lactose, ash, moisture, pH and titratable acidity. The fat content of cream separated skimmed bovine colostrum were determined by Gerber’s method as per the procedure outlined in IS: 1479 (Part II) – (1961). The protein, ash and moisture contents of the sample were determinedas described in AOAC (1990). For cream separated colostrum the lactose and pH contents were determined as prescribed in AOAC, 2000. Titratable acidity (percent lactic acid) of the deffated cow and buffalo colostrum were estimated as per the method described in ISI Handbook, SP 18:1981. D. Statistical analysis Statistical analysis was carried out to study the effect of different parameters on all the dependent variables. The data obtained were tabulated and subjected to statistical analysis performed using IBM SPSS® 20.0 for Windows® software as per the standard procedure of Snedecor and Cochran (1994). RESULTS AND DISCUSSION A. Colostrometer reading of bovine colostrum during first two days after parturition The colostrometer reading showed decline in values for both cow and buffalo colostrum as shown in Table 2. The mean ± SE values of colostrometer readings were 80.50 ±0.04 and 76.56±0.70 for cow colostrum on the first and second days of parturition, while 95.65±0.03 and 87.26±0.07 for buffalo colostrum on the first and second days of parturition respectively. From Table 2, a highly significant difference was observed in the immunoglobulins for first two days after parturition in both cow and buffalo colostrum. These results showed that there was decline in second day as compared with first day. It was inferred that the first day colostrum have high immunoglobulin than the second day. The findings of this study were correlated with the guidelines of the colostrometer given by Biogenics laboratory, USA. As per guidelines given by Biogenics laboratory, Green mark indicates superior colostrum which has 50-140mg/ml, yellow mark indicates marginal colostrum which has 30-50mg/ml and red mark indicates inferior colostrum with 10-30mg/ml IgG. From this, it was concluded that the collected colostrum were of superior quality. The colostrometer is an on-farm primary method that can be utilized by the farmers to detect immunoglobulin easily than other methods like ELISA and immunoblotting (Bartier et al., 2015). B. Proximate analysis for skimmed colostrum during different days The mean ± SE values of the composition of skimmed cow and buffalo colostrum during first two days after parturition were presented in Table 3. It was quite evident from Table 3 shows a decreasing trend for fat, protein and ash in first day 0.70±0.03,1.19±0.08; 18.74±0.18, 19.25±0.13; 0.96±0.03, 1.09±0.06, whereas, 0.65±0.03, 0.83±0.03; 16.10±0.10, 18.51±0.16; 0.77±0.11, 0.84±0.07 in second day for skimmed cow and buffalo colostrum respectively. But lactose and moisture content increased from 2.57±0.11, 2.42±0.14; 75.22±0.08, 74.69±0.11 in first day, to 2.60±0.13, 2.51±0.13; 77.79±0.08, 75.19±0.10 in second day for skimmed cow and buffalo colostrum respectively. In the current study, a significant difference was observed among the composition of skimmed colostrum for the first two days of parturition except lactose which showed non-significant difference. Fat, protein and ash contents showed decreasing trend as the days advanced. Whereas, lactose and moisture contents showed increasing trend on advancement of days in cow and buffalo colostrum. Arain et al. (2008) found that an average fat percentage of buffalo colostrum at the initiation of lactation was 5.44%. Colostrum rich in protein on the first day of parturition decreased gradually from second day and attained normal value during the conversion to milk (Ghosh and Anantakrishnan 1964). Coroian et al. (2013) reported that the lactose concentration from colostrum gradually increased after the colostral period and attained the highest values in regular milk. Das (2009) reported that the values for protein content showed a remarkable decrease during the successive milking after parturition. The day wise report for the composition of skimmed cow and buffalo colostrum showed approximately 1% decline or raise of composition for each day. The result obtained in the current study was in concurrence with the research findings of Parish (1950); Foley et al (1972); Sodhi et al. (1996) who have also narrated the same trend. Small variations that were observed amongst the findings of different investigators might be due to the differences in methods of analysis, or due to the variation between individual animals and breed. C. Physico- chemical properties of skimmed colostrum The physicochemical properties like pH and titratable acidity of both skimmed cow and buffalo colostrum during first two days were shown in Table 4. From the results (Table 4), there was a gradual increase in pH of colostrum as the days advanced. The pH was 6.16±0.016 and 6.21±0.014 for skimmed cow colostrum and 6.27±0.017 and 6.31±0.015 for skimmed buffalo colostrum respectively for the first and second two days after parturition. Similar results were observed by McIntyre et al. (1952), that the pH of colostrum at parturition ranged from 6.0 to 6.61, with an average value of 6.32 and this value increased with time and reached pH 6.5 after 2 weeks According to McCarthy and Singh (2009), the pH of colostrum was lower than that of normal mid-lactation milk. The change in titratable acidity was observed to be high in skimmed cow and buffalo colostrum on first day. It was noted as 0.495±0.002 and 0.415±0.002 for first day and 0.476±0.001and 0.393±0.001 for second day in skimmed cow and buffalo colostrum respectively. Titratable acidity of colostrum is roughly 2 – 2.5 times higher than that of milk (Mitjushin, 1979). Arain et al. (2008) reported that titratable acidity of first day milking colostrum as 0.39±0.01% which decreased to 0.34±0.004%, 0.31 ± 0.003%, 0.33 ± 0.01%, 0.30 ± 0.004% and 0.26±0.004% in second, third, fourth, fifth and sixth subsequent milking days respectively.