Berari is recently recognized as 23^rd goat breed of India, a breed of Vidarbha region of Maharashtra, is low yielding prolific meat breed thriving well in tropical, wet and dry climate. Three weeks before and three weeks after parturition the period as marked by several metabolic alterations and adaptation to new physiological status of the animal consider very critical called as transition period (Araújo et al., 2014). Level of plasma calcium during different physiological stages may vary (Shappel et al., 1987 and Goff et al., 1989). Goats metabolize calcium more efficiently during early lactation when calcium is drained in the milk. When serum calcium levels are decreased, usually less than 6 mg/dl (normal range 8-12 mg/dl) commonly known as milk fever. Although it is generally accepted that ionized calcium is the metabolically active form in the extracellular fluid, it is seldom measured. The measurement of free calcium is clinically more useful. The advantage to measuring ionized Ca is that it tends to be less variable than total plasma Ca (Szenci et al., 1994.). The Ion Selective Electrode (ISE) method currently used for the estimation of electrolytes is the most accurate and rapid method for ionized calcium estimation. Magnesium involved in many physiological functions such as activation of various enzyme system (Romani and Scarpa, 2000). Magnesium plays a key role as an extracellular ion for nerve transmission. Hypomagnesaemia (tetany) occurs during the early stages of lactation in goats. Reproductive problems such as low first service conception rates and silent heat have been related to wide Ca:P ratio and to phosphorus deficiencies.

Materials and Methods

Twelve advanced pregnant Berari goats aged between 2 to 5 years and body weight ranging between 28-30 kg were selected from Berari Goat and Deccani Sheep Research, Demonstration and Training Centre, Borgaon (Manju), MAFSU, Akola, Maharashtra. Blood samples were collected from the jugular vein puncture during morning hours on 14day and 7day before expected date of kidding and subsequently on the day of kidding (0^th day), 7th, 14th and 21^th day postpartum in clot activator sterilized tubes. Clear serum was separated by centrifugation. Serum macro minerals viz. total calcium, phosphorous and magnesium were estimated by using biochemical semi auto analyzer and standard kits supplied by AGD biomedical. Serum ionized calcium (iCa) was estimated by Electrolyte Analyzer by using Ion Selective Electrode (ISE).

Statistical Analysis

Analysis of variance of the data was done by using Completely Randomized Design (CRD) and to study relationship correlation coefficient was calculated according to Snedecor and Cochran (1994).

Results and Discussion

Mean ± SE levels of ionized calcium, total calcium, phosphorus and magnesium during peripartum period in Berari goat is shown in Table 1 and correlation of iCa with these macro minerals during peripartum period in Berari goat is presented in Table 2.

Total Calcium (tCa)

The results show that, on the day of kidding (0^thday) 8.19±0.18 mg/dl value was recorded. The lowest value of 7.40±0.14 mg/dl was obtained on the 14^th day of prepartum and highest value of 9.99±0.17 mg/dl on 21^st day of postpartum. The total calcium level was increased from day 7^th day prepartum to 21^st postpartum. The level of total calcium during prepartum period ranged between 7.40±0.14 to 8.03±0.13 mg/dl, on the day of kidding (0^th day) 8.19±0.18 and during postpartum period ranged between 8.95±0.14 to 9.99±0.17 mg/dl. Serum total calcium level on 14^th day prepartum showed significant (p<0.05) increased on 7^th day before kidding and remained almost similar on the day of kidding (0^th day). After kidding total calcium concentration showed significant increased through day 7^th, 14^th and 21^st of postpartum. Total calcium has shown steady increased from day 7 prepartum to day 21^st postpartum throughout the experimental period. Gurgoze et al. (2009) observed similar trend of calcium level during prepartum and postpartum period in Awassi ewes. However, Talawar et al. (2016) reported significant (P<0.05) reduction in blood serum calcium concentrations in the group of pregnant ewes as compared to control and postpartum group. The levels obtained in present study were agreement with the results reported by Azab and Abdel- Maksoud, (1999); Iriadam, (2007), Soares et al. (2018) in goats and Teleb et al. (2014) and Sharma et al. (2015) in ewes. The decrease in calcium concentration at late gestation could be attributed to increased demand for calcium for mineralization of foetal skeleton and also owing to their supply to the foetal tissue to meet out the increased demand of growing foetus reported by Talawar et al. (2016). Kaushik and Bugalia (1995) reported drop in circulatory concentration of calcium before and at kidding are consequential to mammary drain in colostrum as well as reduced dietary intake and calcium absorption in gut.

Table 1: Mean ± SE levels of ionized calcium and macro-minerals during peripartum period in Berari goat

Means with common superscript does not differ significantly

Table 2: Correlation of ionized calcium with macro-minerals during peri-partum period in Berari goat

Ionized Calcium (iCa)

The ionized calcium concentration on the day of kidding (0^th day) 4.19 ±0.18 mg/dl value was recorded. Serum ionized calcium level on 14^th day prepartum showed significant (p<0.05) increased on 7^th day before kidding. The values decreased significantly (p<0.05) on the day of kidding (0^th day). After kidding ionized calcium concentration showed significant increased through day 7^th, 14^th and 21^st of postpartum. Ionized calcium (iCa) level recorded lowest on the day of kidding whereas highest on 3^rd week after post-partum. Serum iCa level ranged between 4.19 ±0.18 to 4.89±0.16mg/dl during prepartum and postpartum period in Berari goat. The level of iCa recorded in Berari goat in our study is almost half of the level of total calcium recorded, similar finding is also recorded by Caprita et al. (2013) in broiler chickens. Riond et al. (1995) reported average serum Ca 2+ concentrations 52% of those of total calcium. Belonje (1976) reported ionized calcium in lactating ewes and in day old suckling lamb were 4.25 ± 0.49 mg/100 ml and 4.47 ±0.65 mg/100 ml respectively. Dauth et al. (1984) pointed out an importance of ionized calcium estimation for veterinary surgeons and other people involved in the diagnosis and treatment of milk fever. The analysis is easy, cheap, instantaneous and reliable as compared with total calcium. Sava et al. (2005) reported that serum iCa reflect true calcium status of body in health and diseased condition. They suggested that in human being the Ca⁺⁺ levels are independent of serum protein status. However, Agnes et al. (1993) reported that serum pH decided the concentration of ionized calcium as it is negatively correlated with ionized calcium. Ballantine and Herbein (1991) studied levels of ionized calcium in Jersey and Holsteins cows during different stage of lactation. They reported that Jersey cows had lower total calcium (7.47mg/dl) and ionized calcium (4.25mg/dl) than Holsteins cows (8.10 and 4.66 mg/dl). On day of calving the levels of iCa in Jersey cows are in comparable with our results on the day of kidding (0^th day) in Berari goat. Changes in the level of ionized calcium may indicate the contribution of integrated hormonal response occurring during day of kidding in the goat. Tan et al. (1972) also reported decreased of the ionic calcium with the progress of pregnancy in women.

In present study the levels of ionized calcium increased significantly (p<0.05) from day 7^th,14^th and 21^stpostpartum.However in contrast to our study in Berari goat, Riond et al. (1995) reported significant decrease level of serum ionic calcium during day 1 and day 2 postpartum in Brown Swiss and HF dairy cows. Mean plasma ionized calcium during early lactation in our study is in agreement with the levels (4.25 mg± 0.49 /100 ml) reported by Belonje, (1976) in lactating ewes. The literature regarding the level of serum ionized calcium during peripartum period in goat is scanty.  Some workers have studied the levels of ionized calcium in other animals during pregnancy and lactation.

Phosphorous (P)

On the day of kidding (0^th day) the phosphorous concentration value of 5.98±0.20mg/dl was recorded. The lowest value recorded on 14^th day of prepartum and highest values recorded on 21^st day of postpartum. The levels of phosphorus increased steadily from 14^th day pre-partum to 21^st day postpartum during peripartum period in Berari goat. The values of prepartum in comparison with day of kidding and subsequently on the day postpartum differ significantly (p<0.05). From the 7^th day onwards it was increased significantly up to 14^th day postpartum. Phosphorous concentration ranged between (4.70±0.15 to 7.76±0.13 mg/dl) during peripartum period in Berari goat. This range is slightly higher than the values recorded by Krajnicakova et al. (2003) in goat. Our result shows highest concentration of phosphorous on 21^stday post-partum. Similar findings recorded by Tanritanir et al. (2009) in Sirt hair goat, Sansom et al. (1982); Ozyurtul et al. (2007) in ewes and Shinde and Sankhyam (2007) in goat. Alacam et al. (2008) reported lowest phosphorous concentration on 20^th day post-partum in cattle. The trend of phosphorus has showed steady increase from 14^th day prepartum up to 21^st day post-partum. This might be due to maternal bone resorption of available phosphorus to the fast growing foetus inside the uterus for skeleton mineralization. The ever increasing demand of phosphorous by fast growing foetus could be fulfilled by absorbing available phosphorous from circulation or reabsorption from the bones of dam. As dam prioritize the fetus rather than herself (Gurgoze et al., 2009) and also may be due to increase in metabolic process during early lactation, hormonal response in postpartum. However, Krajnicakova et al. (2003) reported non-significant differences in phosphorus levels at the different stages of growth, reproduction, pregnancy and lactation in goat.

Magnesium (Mg)

On the day of kidding (0^th day) 3.12±0.23 mg/dl value of magnesium concentration was recorded. Serum Mg concentration was lowest on 7^th day postpartum and highest values on 21^st day post-partum in Berari goat. Serum magnesium showed significant (p<0.05) increased on 7^th day of prepartum and on the day of kidding then the level slightly decreased on 7^th day of postpartum. The levels of Mg show non-significant increasing trend after 7^th day through day 14^th and 21^st postpartum. Similar trend was also obtained for phosphorous levels in our study in Berari goats. The values of serum Mg increased significantly (p<0.05) from day 14 pre-partum to day of kidding (0^th day). After kidding Mg concentration increased but this increase was statistically non-significant. Our finding corroborated with the values reported by Ozyurtul et al. (2007); Sharma et al. (2015) in ewe, Kulcu and Yur (2003) in cow and Shinde and Sankhyam (2007) in goat. The present results are not in agreement with the report of Sansom et al. (1982), they reported plasma Mg concentration were higher during last 3^rd week of pregnancy but decreased at lambing and for 3^rd weeks after lambing in ewes. Azab and Abdel-Maksoud (1999) recorded plasma Mg significantly (P<0.05) increased at 4 and 3 weeks before parturition and decreased (P>0.05) at 2 and 1 weeks before parturition. This decrease was significant (P<0.05) on the day of parturition in goats. Boudebza et al. (2016) reported highest Mg level in late gestation than on early lactation and during dry periods in ewes. Brenner and Seidel, (1976) in ewes and Talawar et al. (2016) in goat reported no significant change in mineral concentrations at the time of parturition. There was transient increased of Mg²⁺ concentrations than the total Mg during periparturient period signifies the metabolic importance of magnesium concentration (Riond et al., 1995). The change could be carried by physiochemical alteration from mother to the fetus as the magnesium subsequently required for normal skeletal development in fetus while it is constituent of milk in dam.

Correlation of Ionized Calcium with Macro Minerals during Peripartum Period in Berari Goat

There was significant (p<0.05) positive correlation (r =0.536) between ionized calcium and total calcium. Also significant (p<0.05) positive correlation between ionized calcium and magnesium (r=0.480). Total calcium has shown significant (p<0.05) positive relationship with magnesium (r=0.268) and non-significant positive correlation with phosphorous (r =0.002). Serum magnesium level has shown positive significant (p<0.05) correlation with phosphorous (r =0.382) during peripartum period in Berari goat.

Conclusion

The levels of ionized calcium and macrominerals viz. total calcium. Mg and P were estimated during the peri-partum period of the Berari goat. The main objective of the study was to find out the levels of iCa during the peri-partum period of these goats by using ion selective electrode (ISE). The ISE is the most convenient, accurate and reliable method for the estimation iCa.  In our study the iCa levels were almost half the levels of the total calcium. This indicate that the half of the calcium in the blood is in ionized form i.e. biologically active form in these animals serum ionized calcium increased significantly from the day of kidding through 7^th, 14^th and 21^st day postpartum. Serum phosphorus shown increasing trend through day 14^th, 7^th prepartum, day of kidding (0^th day), 7^th, 14^th and 21^st post-partum. Serum Mg concentration lowest on 7^th day postpartum and highest values on 21^st day postpartum without any specific trend. There was significant positive correlation between serum ionized calcium and total calcium and magnesium level during peri-partum period in Berari goat.

Considering the biological importance of ionized calcium and to establish its normal reference range and cut off value of iCa for the accurate diagnosis of various metabolic disorders during peri-partum period in these goats, it is necessary to study this parameter through entire gestation period with more number of samples along with total calcium, total protein, pH and vitamin D status in healthy and animals with subclinical and clinical hypocalcaemia.

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