[ Ana Sayfa | Editörler | Danışma Kurulu | Dergi Hakkında | İçindekiler | Arşiv | Yayın Arama | Yazarlara Bilgi | E-Posta ]
Fırat Üniversitesi Sağlık Bilimleri Veteriner Dergisi
2006, Cilt 20, Sayı 3, Sayfa(lar) 205-209
[ Özet ] [ PDF ] [ Benzer Makaleler ] [ Yazara E-Posta ] [ Editöre E-Posta ]
EVALUATION OF LIVER FUNCTION TESTS IN COWS DURING PERIPARTURIENT PERIOD
Bülent ELİTOK1, Mustafa KABU1, Özgül Mukaddes ELİTOK2
1Afyonkarahisar Kocatepe Üniversitesi, Veteriner Fakültesi, İç Hastalıkları Anabilim Dalı, Afyonkarahisar-TÜRKİYE
2Zirai Araştırma Enstitüsü, Hayvan Sağlığı Bölümü- Afyonkarahisar-TÜRKİYE
Keywords: Cattle, Periparturient period, Liver
Summary
The objective of the study was to determine various liver metabolic changes associated with periparturient period (1 week before calving and 3 weeks after parturition) in dairy cows.

Twenty-one Holstein study cows and eight control from one commercial herd were used all the animals were monitored for bromosulphthalein (BSP) clearence test, liver biopsy and metabolic profile at 1st week before calving, on calving day (day 0), and at 1st, 2nd and 3rd weeks after parturition. Single intravenous injections of BSP were given to cows and the change in plasma BSP concentration with time was analysed for each measurement point. Additionally, metabolic profile as determined at each time during the study.

Analyses of variant indicated that most dramatic changes especially occured at wk 1 before parturition prior to wk 2 after parturition when compared to the other study groups (p<0.05) and non-pregnant cows (p<0.05). Results of the study showed that the periparturient period is very important in cattle life and only one diagnostic test may be mislead for evaluating the changes in the liver functions in the periparturient period. Therefore, performing all the diagnostic tests together are give us more valuable data about during the period in cows.

  • Top
  • Summary
  • Introduction
  • Methods
  • Results
  • Disscussion
  • References
  • Introduction
    The periparturient period for a dairy cow begins two to three weeks prepartum and continues until two to three weeks postpartum 1-3. The measurement of liver functions in this period is a much important advantage for detecting prognose and choosen theraphy appropiately. BSP clearence, one of the most important parameter evaluating liver flow function, is a relatively nontoxic organic anion used as an in vivo indicator of liver performance 4. Following parturition and initiation of lactation, there is a significant increase in the splanchnic tissue mass concomitant with an increase in liver blood flow (LBF) 5. This is probably due to both hypertrophy and hyperplasia of the liver and the organs of the gastrointestinal tract in response to the increase in nutrient intake 6. Further, the concentrations of a number of blood constituents are significantly altered during periparturient period in cattle 7. Serum metabolites, suche as TB, TP, GGT, AST and SDH, seems to be most useful in identifying animals with hepatic disease 4. The dehidrogenases (GLDH) have the shortest half-lives in serum and may not increase in cattle with chronic hepatic disease 4,8. AST comes from tissue other than liver and is not specific for hepatic function. Valuable information concerning dietary protein content and utilization can be detected from herd urea levels 9,10. Blood glucose is an insensitive measure of energy status because it is subject to tight homoeostatic regulation 5. Most of the net accumulation of TG in the liver occurs following calving in response to endocrin changes, depressed feed intake during the week prior to calving 11. One of the most important diagnostic method for liver damages was liver biopsy.

    Although cows may develope fatty liver during calving period mild or moderate fatty liver do not have clinical signs and the condition has been associated with other health and production problems. Therefore, the purpose of the study was to establish any changes that may ocur in LBF, and the other liver function in periparturient dairy cows in order to aid identification of the cows which are likely to develop liver damage.

  • Top
  • Summary
  • Introduction
  • Methods
  • Results
  • Disscussion
  • References
  • Methods
    Animals and study procedures: Twelve pregnant, Holstein (aged between 3 and 7 years; mean 4.4 year ) cows were monitored 1 wk before predicated calving and 3 wks (one wk intervals) for BSP clearence, blood chemistry and liver histopathologic changes, while six non-pregnant non-lactating cows were kept as control group. Plasma BSP clearence, serum chemistry and liver biopsies were obtained from the animals at 1 week prior to calving, on calving day (day 0), and at 1st, 2nd and 3rd weeks after calving. The cows were and had complated one and six lactations. The mean milk yields of the cows in the previous citations had been 6200 kg. The cows calved during March and April and were fed a diet of corn silage, hay and concentrates containing 13% crude protein.

    Measurement of BSP clearence: Analyses of plasma samples for BSP clearence was as described by Cornelius (1980) 4. Blood samples were taken before one gram of dye was injected intravenously. Following 5th and 30 rd minutes, two heparinized blood samples were taken from cows. The BSP concentrations of sample was determined spectrophotmetrically as follows: 2 ml plasma was tranferred to 12x105 mm cuvettes containing 3 ml 0.1 N NaOH. The blank consisted of 2 ml plasma, 3 ml 0.1 N HCl, and 1 ml distilated water. Any spectrophotometer with a wavellength of 565 nm can be used for the BSP deteminations. Standard curves for BSP determinations should be made using 2 m bovine plasma. The BSP concentrations of the samples (miligrams per 100 ml) are next plotted on semilog paper, and the T1/2 for BSP clearence calculated. The T1/2 is that time required for the BSP concentration to be halved in the plasma. The BSP clearence can be expressed clinically in T1/2 unit (minutes).

    Fractional clearence K, or the percentage of dye cleared from the plasma per minute, can easily be calculated from the following formula:

    Liver Biopsy: Liver tissue samples were obtained by biopsy method described by Craig et al. 8. The method was performed as follows: A sample of liver was taken from the animal by percutaneous neddle biopsy under local anaesthesia. The site was in the 11 th intercostal space on the rightchest wall about 20 cm below the rip of the transverse process. Up to 500 mg of liver may be obtained in this way. The sample was placed in a cup with a 10% formalin solution and sent to the laboratory immediately for subsequent determination of structural changes in liver tisue. Tissue sample cut and stained with oil red O stain to demonstrate neutral fat under light microscopy.

    Blood Variables: Blood samples were taken from the jugular vein before the liver biopses were obtained. The serum and plasma samples were harvested within an hour by centrifugation 4ºC for 15 minutes at 3,000 rpm and stored in plastic tubes at −20ºC. Serum biochemical analyses included TP, urea, TB, TG, GLU concentration, and AST, CK, GGT and SDH activities were measured by standart methods using commerical kits supplied from RoscheDiagnostics (D-68298, Mannheim, Germany) in Roche/Hitachi 917 Clinical Chemistry Analyzer.

    Statistical analyses: The BSP clearence and clinical chemistry data were analyzed by paired t tests and compared with those obtained in non-pregnant non-lactating cows by one way analysis of variance. Continuous variables were analyzed as a repeated-measures randomized complete block design, using a general linear mixed models procedures. For all pairwise comparisons, a value of p<0.05 was considered significant. Subsequently, all analyses were carried out using the SPSS (1999) software package.

  • Top
  • Summary
  • Introduction
  • Methods
  • Results
  • Disscussion
  • References
  • Results
    First of all, the actual calving dates were very close to the predicated times. The BSP retention half time both at 5 and 30 min was significantly higher and fractional clearence (K) significantly lower in cows on day 0 and at 1st wk after calving when compared to the other study groups (p<0.05) and non-pregnant cows (p<0.05) (Table 1). The each parameters mentioned above tended to fall back to nearly normal levels at 3 wk after calving. Sampling liver from the cows at time-points before and after calving, higher fat levels were found in the liver tissue at 1st wk prior to calving, higher fat consistency was determined on day calving and 1st wk after calving, and fallen slowly back to the normal level as well as that of non-pregnant, non-lactating cows. TB concentrations in periparturient cows on calving day, at 1 wk were higher than in non-pregnant, non-lactating healthy cows (p<0.05), although there was quite wide individual variation. Furthermore, there were significant higher levels in serum AST and SDH activites at 1st wk before calving, on day calving and 1st wk after calving. The GGT values were slightly increased before parturition, although a significance increase was observed on day 0, at 1st wk after parturition (p<0.05). While the serum GLU values in cows after calving were significantly lower when compared with non-pregnant, non-lactating cows (p<0.05), and peaked at 1st wk, the serum urea concentration was significantly reduced 2 wks after calving when compared with non-pregnant, non-lactating cows (p<0.05).


    Click Here to Zoom
    Table 1: Comparison of results of BSP excretion in periparturient cow wih those from non-pregnant non-lactating cows.


    Click Here to Zoom
    Table 2: Comparison of blood chemistry results in periparturient and non-pregnant non-lactating cows.

  • Top
  • Summary
  • Introduction
  • Methods
  • Results
  • Disscussion
  • References
  • Discussion
    Measurement of BSP clearence T ½ is useful in evaluating liver excretory function in adult cattle 6. In the present study, clearence of BSP was prolonged from 1 st wk before calving to 1st wk post partum cows at 1st wk compared to that in animals at other time-point. The increase in half-time and retention of BSP and decrease in fractional clearence before calving suggested that LBF changes were occuring in the liver during peripartum period. Reid and collins 7 reported that the ultrastructural changes in postpaturient cows particularly the decrease in the volume of rough endoplasmic reticulum and mitochondrial damage, have functional consequences and could account for alterations in the pattern of BSP excretion and in blood chemistry in periparturient cows. In the study, the marked infiltration during periparturient period was similar to results of this study and a previous study performed by Collins et al 2. Furthermore, the serum and liver TG accumulation levels were higher in the study. According to Sevinc et al 13, the accumulation of fat in liver cells and development of fatty liver are caused by reduced synthesis of VLDL (very low density lipoprotein).

    The results of this study were in agreement with previous studies indicating that activities of liver enzymes are sensitive indicators of liver damage in cattle 14,15. Changes in blood concentrations of GLU, TB, TP and AST enzyme activity may all reflect alterations in liver function associated with fat accumulation 15. The AST activity was high 8 of 12 (66%) in cows around parturition in this study, while the highest level was observed on day calving and at 1st wk after parturition. The enzyme is not, however, exclusively a liver enzyme, can come from muscle, as well as from liver, so it is not liver-specific 4. It is possible that the rise in AST activity in plasma around parturition was attri-butable to liver and muscle damage as evidenced by increase in CK aktivities at this time as well as observed in our study. The SDH and GGT values were high in only 4 (30%) of 12 cattle in periparturient period. SDH is a liver specific enzyme in the cattle, but it is not an extremely sensitive test because of serum half-life time is very short. GGT is a fairly sensitive and specific indicator of cholestasis or liver damage 7.

    Our results showed that, as parturition approached, the serum glucose concentration decreased exponently, probably reflecting the increasing demands of the fetus and the mammary gland for glucose. Back out of the parturition (at wk 1 prior to calving and on day calving), plasma glucose concentration increased sharply. Herdt 9 claims that this condition is associated with possibly reflecting hormonal changes at calving that promote gluconeogenesis and glycogenolysis. The result of the study is similar to the previous studies 16-18 which declared during the 1 st wk of lactation, plasma glucose concentration decreased 25%, but by the 2nd wk in action, started to increase exponentially. The same authors claim that the increase may reflect the recovery of feed intake and improving energy status of the cow and higher than those observed in previous studies.

    The low urea concentration in cows after calving in this study could be a reflection of the reduced anabolism of proteins due to fatty infiltration 7. Slightly higher serum bilirubin concentration in the study was determined especially within 2 wk after parturition. Although serum bilirubin level is neither a specific nor a sensitive test for hepatic disease 14, high concentration of bilirubin may compete with BSP for excretion, but there was not an appereant correlation between results of BSP clearence test and bilirubin concentrations in the present study.

    As regards to all of the data, subclinical liver damage occurs well at 1 wk before calving and reached peak at 1 wk after parturition, then slowly fallens back to normal. None of the results of the common tests for liver damage or function were clinically usefull when used alone for detection hepatic disease 2,14, the BSP clearence test associated with the other variables studied in the trial give us important data about liver damage in cattle within periparturient period. Despite therapy is not completely effective in the period, early diagnosing may make prevent possible.

  • Top
  • Summary
  • Introduction
  • Methods
  • Results
  • Discussion
  • References
  • References

    1) Curtis CR, Erb H, Sniffen C, et al. Association of periparturient hypolcalcemia with eight periparturient disorders in Holstein cows. J Am Vet Med Assoc 1983; 5: 559.

    2) Goff JP and Horst RL. Physiological Changes at Parturition and Their Relationship to Metabolic Disorders. J Dairy Sci 1997; 80: 1260–1268.

    3) Grummer RR. Impact of changes in organic nutrient metabolism on feeding the transition dairy cow. J Anim Sci 1995; 73: 2820.

    4) Cornelius CE. Liver function. In: Kaneko JK, ed. Clinical biochemistry of domestic animals. 3 rd ed. New york: Academic Press Inc, 1980; 201-258.

    5) Reynolds, CK, Aikman PC, Lupoli B, et al. Splanchnic metabolism of dairy cows during the transition fromlate gestation through early lactation. J Dairy Sci 2003; 86: 1201–1217.

    6) Mikner JP, Robertson WG. Brom sulphalein fractionel clearence in dairy cattle as a criterion of liver function and the simultaneous determinetion of volumes of plsama and blood. J Dairy Sci 1957; 40: 914-921.

    7) Reid IM, Collins RA The pathology of post-parturient fatty liver in high-yielding dairy cows. Invest Cell Pathol 1980; 3(3): 237-49.

    8) Craig AM, Pearson EG, Meyer C, et al. Serum liver enzyme and histopathologic changes in calves with chronic and chronic-delayed Senecio jacobea toxicosis. Am J Vet Res 1991; 52: 1969.

    9) Herdt TH. Variability characteristics and test selection in herd-level nutritional and metabolic profile testing. Vet Clin N Am Food Anim Pract 2000; 16: 387-403.

    10) Van Saun RJ. Peripartum nutrition: The key to diagnosis and management of periparturient disease. Proc Am Assoc Bovine Pract 1997; 33-42.

    11) Zhu LH, Armentano, LE, Bremmer DR, et al. Plasma concentration of urea, ammonia, glutamine around calving, and relation of hepatic triglyceride, to plasma ammonia removal and blood acid-base balance. J Dairy Sci 2000; 83: 734-740.

    12) Collins RA, Reid IM, Williams LA, et al. Histological measurement of fat content of liver of dairy cows. J Comp Pathol 1985; 95(3): 437-41.

    13) Sevinc M, Basoglu A, Birdane FM. Liver function in dairy cows with fatty liver. Rev Med Vet 2001; 152: 297-300.

    14) Pearson EG, Dirksen G, Meyer J, et al. Evaluation of liver function tests in neonatal calves. J Am Vet Med Assoc 1995; 1; 207 (11): 1466-9.

    15) Reid I, Robert J. Fatty liver in dairy cows. In Practice 1982;164-180.

    16) Bertics JS, Grummer RR, Cadorniga-Valino C, et al. Effect of prepartum dry matter intake on liver triglyceride concentration and early lactation. J Dairy Sci 1992; 75:1914.

    17) Skaar TC, Grummer RR, Dentine MR, et al. Seasonal effects of prepartum and postpartum fat and niacin feding on lactatio performance and lipid metabolism. J Dairy Sci 1989; 75: 184.

    18) Studer VA, Grummer RR, Bertics SJ. Effect of prepartum propylene glycol administartion periparturient fatty liver in dairy cows. J Dairy Sci 1992; 75: 184.

  • Top
  • Summary
  • Introduction
  • Methods
  • Results
  • Discussion
  • References
  • [ Başa Dön ] [ Özet ] [ PDF ] [ Benzer Makaleler ] [ Yazara E-Posta ] [ Editöre E-Posta ]
    [ Ana Sayfa | Editörler | Danışma Kurulu | Dergi Hakkında | İçindekiler | Arşiv | Yayın Arama | Yazarlara Bilgi | E-Posta ]