Horea Samanc

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.

ADRENOCORTICAL AND THYROID FUNCTION, HORMONE AND METABOLITE PROFILES AND THE ONSET OF OVARIAN CYCLICITY IN DAIRY COWS SUFFERING FROM VARIOUS FORMS OF KETOSIS

The involvement of adrenocortical and thyroid hormones in the pathogenesis of ketosis, as well as the ovarian consequences of this metabolic disorder, were studied in _2 parity cows (n=199) in 3 large scale dairy herds. To compare the plasma/serum concentrations of certain hormones Scortisol, thyroxin (T4), triiodothyronine (T3), insulin, insulin-like growth factor-1 (IGF-1)¹ and metabolites Sglucose (G), acetoacetic acid (ACAC), βOH-butyrate (BHB), non-esterified fatty acid (NEFA), trigliceride (TG), total cholesterol (TCh)¹, and the activity of aspartate aminotransferase (AST), blood samples were taken 1 to 3 days after calving and again 4 times 7 days apart. The ACTH-challenged cortisol responsiveness and the TRH-induced T4/T3 increase were determined between days 1 to 3 and again between days 28 to 35. The resumption of ovarian cyclicity was followed up by individual progesterone (P4) profiles based on milk samples taken 3 times a week for about 80 to 85 days. BHB level of 1 mmol/L was estimated as a border line between hyper- (>1 mmol/L) and normoketonaemic (<1 mmol/L) conditions. Five different ketone patterns were distinguished: (1) non-ketotic (n=98; normoketonaemia in all samples), (2) early type ketosis (n=45; hyperketonemia was detected only in the first week after calving), (3) late type (lactational) ketosis (n=11; after a normoketonaemic period increasing hyperketonaemia was detected in the 5th, or in the 4th and 5th weeks), (4) temporary ketosis (n=11; hyperketonaemia was detected for 1-2 weeks in the 2nd and 3rd or in the 3rd and 4th weeks); (5) long-lasting ketosis (n=34; hyperketonaemia has been detected since calving for 4 to 5 weeks or until dying / emergency slaughtering). Simultaneously with the hyperketonaemic stage increased NEFA, ACAC, depressed TCh, glucose and decreased insulin, IGF-1, T4 and T3 concentrations were detected in almost all the cases. Obvious metabolic and endocrine alterations were found, however, only in long-lasting ketosis. The TRH-stimulated T4 and T3 responses remained almost unaffected proving intact thyroid function in early and late type as well as in temporary ketosis. Depressed thyroid response and delayed onset of cyclic ovarian function were detected only in cases of long-lasting ketosis. The cows characterized by lower than normal (<mean-SD of non-ketotic cows) ACTH-stimulated cortisol response on days 1-3 after calving showed poorer chance for spontaneous recovery. There was a significant negative correlation between the IGF-1 level in the 1st week after calving and the duration of the postpartum acyclic period. In late type (lactational) ketosis the cessation of ovarian cyclicity was the most characteristic genital malfunction.

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.

The serum levels of insulin and igf-i in newborn piglets treated with clinoptilolite

The aim of this study was to investigate the influence of the natural mineral adsorber clinoptilolite on the serum levels of insulin and insulin-like growth factor-I in newborn piglets in the first 30 hours postnatally. A total number of 40 crossbred Landrace x Duroc newborn piglets from 4 litters was used. Five piglets from each litter were randomly assigned to the treated group and another five piglets to the control group. The treated animals received 10 ml of 15% clinoptilolite suspension three times: immediately after birth and subsequently at 12 and 24 hours after birth. Mean serum insulin level in the treated newborn piglets was almost 20% higher at both time intervals after treatment but the increases were not statistically significant, due to the high individual variation (44.40±6.33:36.40±5.14 and 17.54±2.61:14.02±1.14 mIU/L, treated vs. control at 10 and 30 hours postpartum). Serum levels of IGF-I were also increased in the treated newborn piglets, and the differences between means were statistically significant (18.20±0.63: 13.70±1.02 and 17.61±0.173:12.48±0.64 nmol/L, p<0.001, treated vs. control at 10 and 30 hours postpartum). Our results indicate that clinoptilolite treatment could effectively increase serum IGF-I and possibly also insulin levels in newborn piglets.

Hormonal status and regulation of glycemia in neonatal calves during the first hours of postnatal life.

The aim of this study was to examine changes in some hormones concentrations in calves during the first 32 hours of neonatal life and to estimate their association with glycemia. Thyrty two Holstein breed calves were selected for the study. Blood samples were taken at 30, 60 and 90 minutes postnatal. Calves received pooled colostrum: primary colostum (1.5 L, 2 hours after birth), secondary colostrum (2 L, 14 hours after birth) and tertiary colostrum (2 L, 26 hours after birth). Blood samples were taken at hours 5, 20 and 32 of neonatal life. Concentrations of glucose, insulin, cortisol, thyroid hormones and IGF-I and abundance of IGFBP-1, IGFBP-2 and IGFBP-3 were determined in the blood serum. The T3/T4 ratio was also calculated. Calves were born hypoglycemic (glycemia was 2.56±1.05 mmol/L at birth). Thereafter, glycemia significantly increased (p<0.001) to 3.05±0.89 mmol/L at min 90. Glucose concentration showed a further increase after colostrum intake and was significantly higher than at the initial value in all examined periods (p<0.001). During the first 90 minutes of neonatal life insulinemia decreased significantly (p<0.001) compared to initial value (26.33±10.05 μIU/L) and it measured 18.66±5.56 μIU/L at min 90. Cortisolemia was highest at minute 30 (85.08±19.36 nmol/L) and than decreased until the end of the experiment (p<0.001) compared to initial values in samples obtained during the period of colostrum intake. A significantly high correlation was determined between glycemia and cortisolemia in all examined periods before the first colostrums intake (r2=0.854; p<0.01 at min 30; r2=0.742; p<0.01 at min 60 and r2=0.551; p<0.01 at min 90). T4 concentrations significantly increased during the first 2 hours, while T3 concentrations decreased, significantly from min 30 to min 90 postnatal (p<0.05). T3/T4 ratio significantly increased during the first 2 hours of neonatal life. After first colostrum intake, concentrations of both hormones rose significantly compared to the initial level, but T3/T4 ratio did not change and maintained the value determined at minute 90. IGF- 1 concentrations significantly decreased during the first 2 postnatal hours. A significant positive correlation was observed between IGF-1 concentration and insulinemia (r2=0.463; p<0.05 at min 30, r2=0.662; p<0.01 at min 60 and r2=0.583; p<0.01 at min 90). IGFBP-3 abundance significantly decreased, while IGFBP-1 significantly increased in this period. IGFBP-2 abundance was highest at birth. Results presented in this study indicate that the increase in glucose concentration during the first 2 hours of neonatal life, before the first colostrum intake is mainly the result of increased activity of the adrenal cortex in cortisol secretion and extrathyroidal tissue thus providing sufficient triiodothyronine. Immaturity of mechanisms responsible for insulin secretion provides the dominance of catabolic processes. Changes of the IGF system provide a rise of glucose concentration and establishment of energy balance.

Effects of buffering mineral mixtures on milk yield, milk composition, rumen pH and some blood biochemical parameters in heat stressed dairy cows.

The objective of the work was to investigate the influence of partial substitution of magnesium oxide with natural bentonite in feed mixtures used in feeding of cows during their exposure to heat stress. The investigation lasted 30 days and was carried out during last ten days of may and first twenty days of June when average air temperature in stables was 36.6±2.5oC. In the experiment there were included 30 cows of Holstein breed in first phase of lactation, which were divided into two groups of 15 cows: control (C) and experimental (E). Group C was fed with experimental mineral mixture that contained 60% of magnesium oxide during the whole investigation period. Group E was fed with experimental mineral mixture that contained 40% of magnesium oxide as well as 20% of natural bentonite. Remaining ingredients in both control and experimental mineral mixtures were the same and also contained 20% of sodium bicarbonate and 20% of zeolite in the same quantities. The control and experimental mineral mixtures were mixed into complete feed mixture (18% UP) in the amount of 1%. At tne end of the investigation period, on the 30th day, there were taken samples of rumens contents for determining pH, and after that blood samples, in which, after the separation of blood serum, were determined glucose concentration, total proteins, albumin, globulin, urea, HDL cholesterol, LDL cholesterol, total bilirubin, calcium and phosphorus, as well as the activity of ALT and AST. By computation there was calculated the ratio between albumin and globulin, ALT and AST, and the ratio between calcium and phosphorus. Daily allowance and milk chemical composition ( percentage of fat, proteins and dry substance) were determined at the end of the investigation period, that is on the 30th day of lactation, for each cow individually. Partial substitution of magnesium oxide with bentonite influenced milk production increase, but it was statistically insignificant. Besides that, in E group of cows, percentage of fat and dry substance in milk was significantly increased (p<0.05 and 0.01 respectively), while percentage of protein increase was insignificant. The substitution of magnesium oxide with bentonite had no impact on the values of examined parameters of metabolic profile, but it led to statistically significant increase of rumen contents pH values (p<0.05). From the obtained results it can be concluded that substitution of magnesium oxide with bentonite in feed mixtures that are used for feeding cows during summer period, can prevent rumen acidosis, which high yielding cows incline to under the conditions of elevated external temperatures. Besides that, this kind of substitution leads to improvement of milk composition, especially when percentage of fat and dry substance in milk is concerned. [Projekat Ministarstva nauke Republike Srbije, br. TR 31003 i br. TR 34013]

The influence of heat stress on metabolic status of cows

It is considered that high air temperature and humidity during the summer are the main factors which adversely affect both the health and production-reproductive performance of high yielding dairy cows. The resulting heath stress leads to a series of changes in endocrine regulation of homeostasis. The changes in hormonal status reflect in some way to the indicators of metabolic status of the cows. The objective of this work was to investigate the influence of heat stress on metabolic status of cows. The experiment was carried out on 20 cows of Holstein-Friesian breed during the summer, in the period from 18th to 45th day of lactation. During the performance of the experiment, the value of heat index (THI) was determined hourly and then the value of average morning (from 10 pm the previous day to 9 am the current day), afternoon (from 10 am to 9 pm the current day) and all-day THI was calculated. Blood sampling was carried out on the 1st, 2nd, 8th, 11th, 14th, 18th, 25th, 29th and 37th day of the experiment, in the morning and the afternoon. On the basis of hourly THI values, whole experimental period was divided into three periods: period A during which the cows were exposed to a extreme high heat stress (THI≥78) at least 7 hours in 24 hours; period B during which the cows were exposed to a moderate heat stress (72≥THI≤78) at least 7 hours in 24 hours; period C during which the cows were not exposed to a heat stress (THI≤72) in 24 hours. The average daily THI in period A (73,25±0,89) was significantly higher (p<0,01, individually) in regard to period B (71,45±0,96) and period C (65,41±2,09). THI was significantly higher in the period B than in the period C (p<0,01). Significantly lower blood glucose value (p<0,05) during the afternoon period in the cows exposed to the extreme heat stress (3,02±0,31 mmol/L) in regard to the morning period (3,14±0,41 mmol/L) points to the fact that in such conditions, metabolism redirects to use of glucose as an energy source because in that way less thermal energy is produced than during decomposition of fatty acids. Concentration of most important metabolic profile parameters in blood (cholesterol, triglycerides, total proteins, albumin, urea, total bilirubin, calcium, inorganic phosphorus as well as AST and ALT activity) did not vary significantly under the influence of heat stress. The exception was ionic calcium concentration which, under the conditions of extreme heat stress, was on the lower limit of physiological values (1.17±0.16 mmol/L).

A comparison of the concentrations of energy-balance-related variables in jugular and mammary vein blood of dairy cows with different milk yield

The aim of this study was to compare the concentrations of blood variables obtained simultaneously from the jugular and mammary veins of dairy cows. Eighty Holstein cows were divided into four equal groups: dry, low- (LY), medium- (MY) and high-yielding (HY). Blood insulin, glucose, non-esterified fatty acid (NEFA), beta-hydroxybutyrate (BHBA) and urea concentrations were measured. The jugular and mammary vein (J/M) ratio between concentrations of each variable was calculated. Differences between the groups of cows in concentrations of variables in the jugular vein were not in accordance with those obtained for the mammary vein. J/M values for insulin and glucose concentrations were above 1.0 in all groups of cows. The ratios for NEFA and BHBA concentrations were under or equal to 1.0 in dry and LY cows but above 1.0 in the MY and HY groups, indicating that in MY and HY cows those metabolites are apparently utilised by the mammary gland. J/M values for urea were above 1.0 in dry and LY cows but less than 1.0 in groups MY and HY, indicating that in the latter case urea is apparently released by the mammary gland. In conclusion, J/M for NEFA, BHBA and urea may be useful for estimation of the critical point when the mammary gland receives insufficient energy precursors for its current activity.

Blood concentration of proteins, bilirubin and glucose in cows with left displaced abomasum.

The concentration of total proteins, albumin, total bilirubin, and glucose were examined in the blood of healthy cows and those with left displaced abomasum. Significant digressions from physiological values in cows with left displaced abomasum were established in proteinemia (x = 87.92 g/l) and in bilirubinemia (x = 10.29 μmol/l). Hyperproteinemia indicates chemoconcentration in the diseased animals, which is also indicated in significantly higher concentrations of albumin in the diseased in comparison with the healthy animals (x = 41.94 - 3.5 : 36.89 - 3.95 g/l). The higher values for glucemia in the diseased against the healthy animals (x = 2.628 : 2.203 mmol/l) could indicate disrupted function of B-cells of the endocrine pancreas. This data can come in useful in setting the diagnosis, but it also has no less importance in the determination of the prognosis for the disease. Determining the liver function during the disease should contribute to the better knowledge of its role in the degree of the occurrence of this health disorder, as well as the outcome of the disease itself. This is of particular importance having in mind that displaced abomasum most frequently occurs in the early stage of lactation, when a negative energy balance is already present. This state is conducive to the occurrence of fatty liver, and that is why displaced abomasum can contribute even further to the process of fat accumulation, having in mind that diseased animals consume significantly smaller quantities of feed.