In addition to the increased energy requirement during and after calving in dairy cows, the initiation of colostrum-milk production causes aggravation of NEB.
The body condition score measurement is used to determine the NEB status of cows under field conditions 5,39,40. It is stated that there are important relationships between BCS changes and the management of metabolic processes, milk yield, fertility and general health status in dairy cattle 41,42. Dairy cows with a body condition score of 2.5-≤3.5 were considered to be in good condition, and those with a body condition score of >3.5 were considered to be a high body condition 43,5. The dairy cows we used in our study were divided into two groups as those with a BCS of ≤ 3.5 (good condition) and as those with a BCS of >3.5 (high condition) in accordance with the limitations of BCS values stated by the researchers. In this study, we aimed to evaluate the relationships between the values of BCS, colostral IgG content, liver, lipid metabolism and oxidative stress parameters in the cows of both groups.
Roche et al. 5, have stated that it is possible that the metabolic process can be successfully managed by evaluating the changes in the levels of parameters related to energy metabolism in the postpartum period in dairy cows. Similarly, in their study evaluating liver and lipid metabolism, Çolakoğlu and Küplülü 28 point out that the postpartum metabolic process in cows can be successfully monitored by taking into account the changes in BCS, NEFA and BHBA values. Some authors found these values to be at the lowest level in the cows with a birth BCS of 3.0-3.25. Podpecan et al. 44 concluded that it is important to examine liver and lipid-related parameters and metabolic factors in evaluating the metabolic profile of cattle on a herd basis. Zhao et al. 29, stated that blood serum NEFA, BHBA, MDA and SOD values determined in the cows with a birth BCS of 4.5-5.0 were higher than the values in the cows with a birth BCS of 3.0-4.25. Turk et al. 45 and Drackey et al. 46 point out that postpartum lipid mobilization and oxidative stress are the part of a complex series of metabolic adaptation parameters. They have evaluated the blood serum levels of triglyceride, total cholesterol, HDL, urea, creatinine, glucose, total protein, AST and PON-1. As a result, they determined that in the transition period, the blood serum triglyceride, total cholesterol, HDL-C, BHB, FFA, TAS and PON1 levels were significantly affected. Aviram et al. 23 and Trevisi et al. 24 indicated that liver function markers are closely related with the blood serum albumin, bilirubin, cholesterol and PON-1 levels.
Bernabucci et al. 15 and Gheise et al. 32, stated that cows with a higher calving BCS are more susceptible to oxidative stress due to postpartum body reserve losses and changes in metabolic processes. Folnozic et al. 33, evaluated the birth BCS of 3.35-3.75 in the cows astheideal body condition, while a BCS of >4,0 as adiposity. In addition, they found blood serum triglyceride, HDL, cholesterol and NEFA levels to be higher in the cows they evaluated as having an ideal body condition, compared to the values they determined in the cows scored as adiposity. But they have not found significant differences in the case of blood serum BHBA concentration during the transition period in both groups. O'Boyle et al. 34, pointed out that there is an increase in oxidative stress and a decrease in serum NEFA in cows with high postpartum BCS, but that negative energy balance did not occur in these cows. Çolakoğlu et al. 35, found the blood serum MDA level in the cows with a birth BCS of 2.75-3.0 to be higher than that of in the cows with birth BCS of 3.25-3.75. Same authors stated that the incidence of oxidative stress and metabolic diseases increased in the cows with low birth BCS values. They also found that the cows with low BCS values had lower glucose concentrations than those with adequate values. In our study, it has been evaluated that the decrease in the serum SOD level and the increase in the MDA level in cows with BCS>3.5 may have occurred as a result of lipid peroxidation and superoxide dismutation due to the increase in oxidative stress. We evaluated that cows with high birth BCSs were more susceptible to oxidative stress due to loss of body reserve and changes in metabolic processes. In addition, no significant difference was observed in blood BHBA concentrations between the two groups. In our study, serum glucose and BHBA levels were found to be lower in cows with a BCS of ≤3.5 than in cows with a BCS of >3.5. Blood serum urea, creatinine, total protein and total cholesterol levels were found to be higher in cows with a BCS of ≤3.5 than in cows with a BCS of >3.5. However, the changes in these parameters, which were not statistically significant, were found to be compatible with the results of various investigators (35, literature).
Sevinç et al 36, reported after evaluating serum GGT, AST and bilirubin levels that they provide important data regarding lipid metabolism and liver functions which change depending on NEB. Concerning the development of NEB, the liver is the organ which is the main provider and location of the energy conversion in which lipid metabolism also plays a role 47. Zhou et al. 37, have evaluated the liver-specific plasma protein albumin and the liver/intestinal lipoprotein cholesterol in cows 3 and 28 days after birth, and they noted that there were significant correlations between the parameters related to milk yield and the parameters indicative of liver function. In our study, when compared with the values in the cows with a BCS of 3.96±0.14; in the cows with a BCS of 3.24±0.24 serum NEFA, HDL, PON-1and MDA values were found to be lower and serum triglyceride, albumin, SOD, and colostral IgG values were found to be higher. The statistically significant increase in serum PON-1, NEFA and HDL levels and a rather major decrease in serum triglyceride and albumin levels in cows with a BCS of 3.96±0.14 may be associated with lipid mobilization resulting from the development of NEB. The low serum protein, albumin and colostral IgG levels in cows with a BCS of 3.96±0.14 compared to the values in the other group suggest that the immune system might be suppressed in cows with a BCS value of >3.5. These results show that the increase in oxidative stress activity resulting from the development of postpartum NEB in cows with BCSs of >3.5 causes more severe disruption in the energy metabolism balance and leads to the emergence of higher levels of oxidative stress products. Immune system suppression, which is thought to occur in direct proportion to the severity of NEB developing in dairy cows with a high postpartum BCS value, leads to a decrease in colostral IgG levels. Conneely et al. 8 stated that there is a significant inverse correlation between colostral IgG levels and BCS value in dairy cows. Shearer et al. 48 reported that there is a relationship between the increase in the BCS and the amount of colostral IgG in cows in the dry period. Contrary to the opinions above, Immler et al. 49 stated that they could not find a relationship between BCS and colostrum quality in their study, in which they evaluated colostrum quality with a Brix refractometer. Abdullahoğlu et al. 50, determined that the increase in colostral IgG value in cows with a BCS of 3.5 was not statisticaly significant compared to the values determined in cows with BCSs of 2.5-3.0 and 4.0. Soufleri et al 51, while they could not find a significant difference between BCSs and colostrum total solid contents, they determined a significant negative relationship between colostrum yield and BCS values and reported that they could obtain less colostrum from cows with BCSs of >3.50. In our study, colostral IgG level was found to be significantly lower in cows with BCSs of >3.5 compared to cows with BCSs of ≤3.5. This result can be interpreted as the suppressive effect of oxidative stress and increase in lipid metabolism metabolites on the immune response in cows with BCSs of >3.5.
When blood serum BHBA, NEB, liver and lipid metabolism parameters, oxidative stress markers and colostral IgG levels were evaluated together with BCS values in postpartum dairy cows, it was concluded that a BCS change of <0.5 from dry period to calving and a postpartum BCS of ≤3.5 are beneficial for better management of lipid metabolism and oxidative stress and higher colostral IgG level in cows.
Conflict of Interest
The authors declared that there is no conflict of interest.