Danijela Kirovski

Thyroid Hormones Concentrations during the Mid-Dry Period: An Early Indicator of Fatty Liver in Holstein-Friesian Dairy Cows

Relationship between postpartal fatty liver and thyroid gland activity during the peripartal and mid dry periods was studied. Twenty one dry cows were chosen. Blood samples were obtained on days −30, −2, and +12 related to calving and analized for thyroxine (T4) and triiodothyronine (T3). A T3/T4 ratio was calculated. Liver tissue samples were taken 12 d after calving and tested for the lipid content. Cows were divided into three groups: mild (<20% fat), moderate (20 to 30%), or severe fatty liver (>30%). Cows, that were affected with severe fatty liver, were hypothyroid prior to development of the condition due to lower T4 concentrations, and had significantly lower concentration of T3 and higher T3/T4 ratios than cows with mild and moderate fatty liver. Thus, hypothyroid state during mid-dry period may be an early indicator of postpartal fatty liver and may provoke T3/T4 ratio increase in this group of cows.

NEW INSIGHTS INTO BODY CONDITION SCORE AND ITS ASSOCIATION WITH FATTY LIVER IN HOLSTEIN DAIRY COWS

The aim of this study was to estimate the association between body condition and fatty liver in high-yielding dairy cows. One hundred dry Holstein cows were selected. Cows were scored once for body condition during the dry period, puerperium and month 2 of lactation, according to the system provided by Elanco Animal Health Buletin Al 8478. Body condition loss was determined as marked if loss was over 0.7 points between two consecutive phases of cycles and over 1.5 points between puerperium and month 2 of lactation. Liver tissue samples were taken 12 d after calving and tested for lipid content. 50% of cows had mild (3.92 ± 3.33% fat), 33% moderate (19.28 ± 5.18% fat), and 17% severe fatty liver (36.21 ± 4.55% fat). The mean body condition scores were 3.79 ± 0.55 (dry period), 3.18 ± 0.34 (puerperium) and 2.90 ± 0.29 (month 2 of lactation). Marked body condition loss from the dry period to puerperium had 38% of cows, 20% from dry period to month 2 of lactation and 8% from puerperium to month 2 of lactation. Body condition scores out of the physiological range had 39% dry cows, 49 % cows in puerperium and 9% cows at month 2 of lactation. After dividing cows into groups according to fatty liver degree, it was shown that only cows with severe fatty liver were obese during the dry period and that 76.47% of cows from this group had marked condition loss from the dry period to puerperium, 47.06% from dry period to month 2 of lactation and 23.53% from puerperium to month 2 of lactation. These indicate that in cows with severe fatty liver lipomobilisation is intensive and starts around calving, before milk production enhacement. Our results indicate a strong association between body condition and fatty liver in cows, which can be estimated only when body condition is analyzed in details. Besides, our results clearly indicate that body condition is not the only etiological factor that leads to fatty liver in dairy cows.

Application of the metabolic profile test in the prediction and diagnosis of fatty liver in Holstein cows

The aim of this study was to examine the possibility of using results of metabolic profile test in the prediction and diagnosis of fatty liver in Holstein cows. Forty dry cows, 5 to 7 days before calving, were chosen from the commercial dairy herd and included in the study. Four blood samples were taken by jugular venipuncture from each animal: 5 to 7 days before expected calving (dry period), as well as on day 12, 30 and 60 of lactation. Concentrations of glucose, β-hydroxybutyrate (BHBA), total protein, albumin, urea, total bilirubin, calcium and phosphorus concentrations were measured in all blood samples. On day 12 after calving, liver percutaneous biopsies were obtained using a biopsy instrument. Liver tissue lipid content was determined by pathohistological determination. Cows were divided into two groups of equal size based on the degree of lipid accumulation in the liver: healthy cows (0.00 fat, n = 20) and cows with fatty liver syndrome (>20% fat, n = 20). Milking was measured each day from day 7 to day 60 of lactation. Results showed that 5 to 7 days before calving, as well as 12 days after calving, BHBA concentrations were significantly higher (p<0.001, respectively) in diseased cows than in healthy cows. Additionally, the concentration of glucose was significantly lower (p<0.01) and the concentration of total bilirubin significantly higher (p<0.001) in diseased compared to healthy cows, at day 12 of lactation. Thirty days after calving, concentrations of albumin, glucose, BHBA and Ca were significantly lower in diseased compared to healthy cows (p<0.05, p<0.01, p<0.01 and p<0.001, respectively). At day 60 after calving, concentrations of biochemical parameters did not differ between diseased and healthy cows. The lactation curve differed in diseased compared to healthy cows, starting from day 26 of lactation. Starting form that day until day 60 of lactation average daily milk production was significantly higher in healthy than in diseased cows, except on day 32 of lactation when the difference was not significant. Based on these results it can be concluded that the metabolic profile test may be a reliable tool for the prediction and diagnosis of fatty liver in Holstein cows.

Obesity-driven prepartal hepatic lipid accumulation in dairy cows is associated with increased CD36 and SREBP-1 expression.

We investigated the hypothesis that obesity in dairy cows enhanced expression of proteins involved in hepatic fatty acid uptake and metabolism. Sixteen Holstein-Friesian close-up cows were divided into 2 equal groups based on their body condition score (BCS) as optimal (3.25≤BCS≤3.5) and high (4.0≤BCS≤4.25). Intravenous glucose tolerance test (GTT) and liver biopsies were carried out at day 10 before calving. Blood samples were collected before (basal) and after glucose infusion, and glucose, insulin and non-esterified fatty acid (NEFA) levels were determined at each sample point. In addition, β-hydroxybutyrate and triglycerides levels were measured in the basal samples. The liver biopsies were analyzed for total lipid content and protein expression of insulin receptor beta (IRβ), fatty acid translocase (FAT/CD36) and sterol regulatory element-binding protein-1 (SREBP-1). Basal glucose and insulin were higher in high-BCS cows, which coincided with higher circulating triglycerides and hepatic lipid content. Clearance rate and AUC for NEFA during GTT were higher in optimal-BCS cows. The development of insulin resistance and fatty liver in obese cows was paralleled by increased hepatic expression of the IRβ, CD36 and SREBP-1. These results suggest that increased expression of hepatic CD36 and SREBP-1 is relevant in the obesity-driven lipid accumulation in the liver of dairy cows during late gestation.

Placental Iodothyronine Deiodinases Expression in Pregnant Cows Exposed to Propylthiouracil (Ptu) and Thyroid Axis Activity of their Calves

Abstract The aim of our study was to investigate if the thyroid axis of newborn calves is affected by prenatal application of propylthyouracil (PTU). The study included 20 late pregnant Holstein cows. One group (n=10) was treated with PTU (4 mg/kg of BW daily) from day 20 before expected calving until the day of calving. The other group (n=10) was non-treated. Placental samples of dams were obtained for measuring mRNA expression of iodothyronine deiodinases type I (D1), type II (D2) and type III (D3). After parturition calves were separated from the dams and included in the study. Blood samples were taken daily from each calf starting on the day of birth until day 7 of age. Blood T3, T4 and TSH concentrations were measured. PCR analysis of the placental tissue revealed an abundance of all three types of placental deiodinases in non-treated cows, and a significant elevation of mRNA levels for all three types of deiodinases after PTU treatment. Calves that originated from dams treated with PTU had significantly lower T3 and T4 and significantly higher TSH concentrations compared to non-treated calves during the first 2 days of life. Starting from day 4 until day 6 of life the opposite effect was observed meaning that calves prenatally exposed to PTU had significantly higher T3 and T4 and slightly lower TSH. Our study, for the first time, provides information related to iodothyronine deiodinases mRNA expression in bovine placenta, and confirm that PTU treatment of pregnant dams provokes depression of thyroid function in newborns during the first days of life.

Relationship between the indexes of insulin resistance and metabolic status in dairy cows during early lactation

Abstract Insulin resistance is a phenomenon which accompanies the ongoing metabolic adaptation in cows during early lactation. The aim of our study was to determine the linear correlations of HOMA (Homeostatic Model Assessment), QUICKI (Quantitative Insulin Sensitivity Check Index) and RQUICKI (Revised Quantitative Insulin Sensitivity Check Index) indexes of insulin resistance with the metabolic status of cows (concentration of hormones, metabolites and body condition score). The experiment included 40 Holstein-Frisian cows in the first week after calving. Indexes of insulin resistance valued: 18.68±5.43 (HOMA), 0.39±0.06 (QUICKI) and 0.45±0.06 (RQUICKI). Linear correlations were examined by testing the coefficient of correlation (r), determination (r2,%) and regression parameter beta (b) in linear equation. A negative correlation was found between HOMA and IGF-I (insulin growth factor I) (r=−0.51, r2=25.0, b=−1.1257, p<0.01). HOMA showed a positive correlation with BHB (betahidroxybutyrate) (r=0.48, r2=23.2, b=0.0234, p<0.01). A positive correlation was found between QUICKI and IGF-I (r=0.30, r2=10.0 b=46.7900, p<0.05) and cholesterol (r=0.44, r2=18.3, b=1.9021, p<0.01). In contrast, QUICKI and BHB (r=0.51, r2=27.1, b=−1.7241, p<0.01), just like QUICKI and BCS (r=0.46, r2=20.9, b=−2.424, p<0.01), showed a negative correlation. RQUICKI showed positive correlations with IGF-I (r=0.48, r2=22.8, b=28.1230, p<0.01), T4 (r=0.47, r2=22.1, b=87.142, p<0.01) and triglycerides (r=0.36, r2=13, b=0.0407, p<0.05) but negative correlations with cortisol (r=−0.36, r2=13.0, b=−9.0332, p<0.05), STH (somatotropic hormone) (r=−0.42, r2=17.3, b=−5.4976, p<0.01), BHB (r=−0.62, r2=38.3, b=−1.1872, p<0.01), total bilirubin (r=−0.58, r2=33.7, b=−7.131, p<0.01) and BCS (body condition score) (r=−0.6, r2=36.4, b=−1.8347, p<0.01). In conclusion, indexes of insulin resistance may be used to evaluate the metabolic status of cows in early lactation. RQUICKI might be the most appropriate predictor of metabolic status due to its linear relationship with most of the parameters included in homeorhetic process.

The Dynamics of Biochemical Parameters in Blood of Clinically Healthy Holstein Cows from Day 5 before to Day 60 after Calving

Abstract The peripartal period in Holstein dairy cows is critical, due to the transition from pregnancy to lactation. We have studied the dynamics of biochemical parameters from day 5 before to day 60 after calving. The study included 10 multiparous Holstein cows, examined at days -5, 5, 10, 30 and 60 relative to calving. Blood samples were taken from vena jugularis. Analyzed biochemical parameters were glucose, triglycerides, total cholesterol, total bilirubin, albumin, total protein, urea, NEFA and BHBA. Milk production and body condition score were also estimated. Obtained results showed that cows were exposed to mild to marked metabolic distress. Energy status was changed due to increased values of NEFA and BHBA and decreased value of glucose after calving. Protein concentrations were increased at day 10 after calving, despite the decrease of the level of albumin. Urea concentrations before and after calving were within physiological range indicating an optimal protein diet. Increased values of total bilirubin at day 5 after calving indicated liver increased activity. Lipid status presented by triglycerides and total cholesterol revealed no differences in blood concentrations. Milk production was highest at day 30 after calving. BCS were highest in dry cows, thereafter they declined and recovered at day 60 after calving. In conclusion, biochemical parameters can be used as relevant indicators of metabolic distress in cows around calving with milk and BCS recording as aside parameters. Changes in some biochemical parameters indicate liver increased activity and metabolic stress, that could lead to decreased milk production, impaired reproductive performance and, finally, to illness.

Serum Protein Electrophoretic Pattern in Neonatal Calves Treated with Clinoptilolite

The objective of our study was to determine the effects of clinoptilolite supplemented in colostrum on the blood serum protein electrophoretic pattern of new-born calves. Methods: Romanian Black and White new-born calves involved in the study were divided into 3 groups: the control group (C) that received colostrum without clinoptilolite, and experimental groups I (E1) and II (E2) that received colostrum supplemented with 0.5% and 2% clinoptilolite, respectively. The concentration of total protein and protein fractions (albumin, α1-globulin, α2-globulin, β-globulin and γ-globulin) were analyzed by electrophoresis on cellulose acetate. Results: At hour 30 after birth, concentrations of γ-globulins, β-globulin and total protein in E1 group of calves were higher than in control group by 42.11% (p < 0.05), 28.48% (p > 0.05) and 18.52% (p > 0.05), respectively, and were higher, but not significantly, in group E2 compared to the control group. This was in accordance with a significant lower albumin/globulin ratio in groups E1 and E2 (29.35%, p < 0.05 and 35.87%, p < 0.05, respectively) than in control group at 30 h postpartum, which indicates an obvious increase of the globulins fraction in experimental groups. The conclusion: Clinoptilolite was effective in improving passive transfer in new-born calves, but it was more effective if added in colostrum with a dose of 0.5% than with a dose of 2%.

Preventing ectoparasite infestations reduces glucocorticoid concentrations in the hair of cows – short communication

The aim of this study was to compare hair corticosteroid concentrations in ectoparasiticide-treated (n = 10) and non-treated (n = 12) Holstein cows. Animals in the treated group received cyfluthrin three times, on days 0, 28 and 56 of the experiment. Hair samples were collected from all cows on days 0, 21, 42, 63, and 84 of the experiment for the determination of cortisol and corticosterone concentrations using immunoassays. The respective hair cortisol concentrations in the treated group averaged 209.78, 165.10, 260.78, 177.44 and 183.11 ng/g, while in the non-treated group hair cortisol concentrations averaged 172.58, 243.58, 309.73, 199.75 and 207.09 ng/g. These results indicate that the control of ectoparasites reduced hair cortisol levels in dairy cows. The respective hair corticosterone concentrations in the treated group averaged 19.06, 22.95, 21.95, 21.60 and 24.84 ng/g and in the non-treated group the hair corticosterone concentrations averaged 17.28, 21.94, 34.05, 26.27 and 26.91 ng/g. The results suggest that longterm stress can be estimated better by the determination of hair cortisol rather than corticosterone concentrations.

Field Trial on Glucose-Induced Insulin Response in High-Yielding Dairy Cows under Different Environmental Temperatures

Abstract This study aimed to evaluate glucose-induced insulin response in cows exposed to different temperature-humidity index. Twenty early lactating Holstein-Friesian cows were divided into 2 equal groups based on season, as summer (SU) and spring (SP). SP cows were not exposed to heat stress, while SU cows were exposed to moderate or severe heat stress. Milk production was recorded daily. Starting from day 30 of lactation, intravenous glucose tolerance test (IVGTT) was carried out three times at 30-day intervals. Blood samples were taken before (basal) and after glucose infusion, and glucose and insulin were measured at each sample point. The homeostatic model assessment (HOMA) index was calculated. Milk yield from days 30 to 40 and 64 to 90 of lactation were higher in SP cows than in SU cows. Basal glucose did not differ on days 30 and 60 of lactation, while basal insulin and HOMA were lower in SU compared to SP cows. On day 90 of lactation, SU cows had higher basal glucose, whereas basal insulin and HOMA did not differ. IVGTT results revealed that glucose tolerance was affected by heat stress such that SU cows had higher glucose clearance. Insulin responses to IVGTT did not differ on days 30 and 60 of lactation. Heat stress had a marked effect on insulin secretion on day 90 of lactation, illustrated by higher increments, peak concentrations and area under the curve for insulin in SU cows. Overall, season differences in glucose tolerance depend not only on heat stress and milk production but also on the stage of lactation.