Concentrates For Dairy Cows Research Articles

Effects of dietary clinoptilolite on reproductive performance, serum progesterone and insulin-like growth factor-1 concentrations in dairy cows during pregnancy and lactation.

The objective of this study was to evaluate the effects of dietary zeolite clinoptilolite on re- productive performance, serum progesterone and insulin-like growth factor 1 (IGF-1) concentra- tions in 78 Holstein Friesian (HF) cows during pregnancy and lactation. The cows were divided into two groups comprising 40 (control group; CON) and 38 (CPL group) cows. To assess repro- ductive performance of HF cows the following variables were registered: the interval from calv- ing to first insemination (days open to first service, DFS), the interval from calving to pregnancy (days open to pregnancy, DOP), and the number of services per pregnancy (NSP). The average values of progesterone (5.64±0.59 ng/mL vs. 5.16±0.64 ng/mL) were not statistically different (p⟨0.05) and IGF-1 levels (400.17±17.72 ng/mL vs. 348.36±20.39 ng/mL) were higher in the CON than in the CPL group which received 50 g of clinoptilolite twice a day. However, in the CPL group ovarian cyclity resumed on days 40 and 60 postpartum. In addition, DFS (p⟨0.05) and DOP (p>0.05) were shorter in the CPL than in the CON group (115.1±19.9 and 137.5±36.3 days vs. 124.2±17.3 and 143.8±33.5 days, respectively). During 305 days of lactation, milk production was higher in the CPL vs. CON (8325.5±628.8 kg vs. 8050±586.8 kg). The NSP was lower in the CPL than in CON group (1.91 vs. 2.14). The dietary clinoptilolite supplement had a positive in- fluence on milk yield, exhibited modulating effects on endocrine status of dairy cows, and im- proved reproductive performance, with the decreased NSP, and fewer DFS and DOP.

Assessment of plasma nitric oxide concentration and erythrocyte arginase activity in dairy cows with traumatic reticuloperitonitis

The aim of this study was to evaluate plasma nitric oxide (NO) concentrations, erythrocyte arginase (ARG) activity, plasma fibrinogen (Fb) and serum iron (Fe) levels and some biochemical parameters in dairy cows with traumatic reticuloperitonitis (TRP). The animal material of the study consisted of 14 Swiss Brown cows diagnosed with TRP (TRP group) between 4-8 years old brought to Firat University Animal Hospital Clinics and 14 healthy Swiss Brown cows (control group) aged 4-8 years obtained from dairy farms in different regions. Blood samples were taken from the vena jugularis of the animals. Concentrations of plasma NO, Fb, erythrocyte ARG activity, and some biochemical markers were determined after the serum and plasma of the receiving blood were separated. While the NO (318.9±5.8 vs. 270.3±9.6 μmol/L) concentrations of the TRP group were found to be significantly higher than the control group (P<0.001), the erythrocyte ARG activity (29.5±0.5 vs. 35.2±1.0 U/hb) was found to be higher in the control group (P<0.001). It was also observed that total protein (TP) (6.6±0.5 vs. 7.8±0.1 g/dL) (P<0.05) and Fb (914.3±68.6 vs. 265.4±19.8 mg/dL) (P<0.001) concentrations were higher in the TRP group, compared to the control group, while albumin (ALB) (1.9±0.2 vs. 3.1±0.1 g/dL) and Fe (47.00±5.29 vs.106.79±9.44 μg/dL) concentrations were significantly lower than the control group (P<0.001). In addition, a positive correlation was found between NO and Fb concentrations and between erythrocyte ARG activity and Fe concentrations. As a result, it was determined that NO concentrations were increased and erythrocyte ARG activity was not significant in dairy cows with TRP. In addition, increased plasma Fb concentration and decreased serum Fe concentration were determined in dairy cows with TRP. This study demonstrated that plasma NO, Fb and serum Fe concentrations in dairy cows with TRP may be useful markers for prognosis.

Phenotypic and genetic analysis of milk and serum element concentrations in dairy cows

Enhancing micronutrient (i.e., mineral and vitamin) concentrations within milk and serum from dairy cows is important for both the health of the cow and the nutritive value of the milk for human consumption. However, a good understanding of the genetics underlying the micronutrient content in dairy cattle is needed to facilitate such enhancements through feeding or breeding practices. In this study, milk (n = 950) and serum (n = 766) samples were collected from Holstein-Friesian dairy cows (n = 479) on 19 occasions over a 59-mo period and analyzed for concentrations of important elements. Additionally, a subset of 256 milk samples was analyzed for concentrations of vitamin B12. Cows belonged to 2 genetic lines (average and highest genetic merit for milk fat plus protein yield) and were assigned to 1 of 2 diets based on either a by-product or homegrown ration. Univariate models accounting for repeated records were used to analyze element and vitamin B12 data and investigate the effect of genotype and feeding system as well as derive estimates of variance components and genetic parameters. Bivariate models were used to study correlations both within and between milk and serum. Only concentrations of Hg in milk were seen to be affected by genotype, with higher concentrations in cows with high genetic merit. In contrast, element concentrations were influenced by feeding system such that cows fed the homegrown diet had increased milk concentrations of Ca, Cu, I, Mn, Mo, P, and K and increased serum concentrations of Cd, Cu, Fe, Mo, and V. Cows on the by-product diet had increased milk concentrations of Mg, Se, and Na and increased serum concentrations of P and Se. Heritability (h2) estimates were obtained for 6 milk and 4 serum elements, including Mg (h2milk = 0.30), K (h2serum = 0.18), Ca (h2milk = 0.20; h2serum = 0.12), Mn (h2milk = 0.14), Cu (h2serum = 0.22), Zn (h2milk = 0.24), Se (h2milk = 0.15; h2serum = 0.10), and Mo (h2milk = 0.19). Significant estimates of repeatability were observed in all milk and serum quantity elements (Na, Mg, P, K, and Ca) as well as 5 milk and 7 serum trace elements. Only K in milk and serum was found to have a significant positive genetic and phenotypic correlation (0.52 and 0.22, respectively). Significant phenotypic associations were noted between milk and serum Ca (0.17), Mo (0.19), and Na (-0.79). Additional multivariate analyses between measures within sample type (i.e., milk or serum) revealed significant positive associations, both phenotypic and genetic, between some of the elements. In milk, Se was genetically correlated with Ca (0.63), Mg (0.59), Mn (0.40), P (0.53), and Zn (0.52), whereas in serum, V showed strong genetic associations with Cd (0.71), Ca (0.53), Mn (0.63), Mo (0.57), P (0.42), K (0.45), and Hg (-0.44). These results provide evidence that element concentrations in milk and blood of dairy cows are significantly influenced by both diet and genetics and demonstrate the potential for genetic selection and dietary manipulation to alter nutrient concentration to improve both cow health and the healthfulness of milk for human consumption.

Low abundance of mitofusin 2 in dairy cows with moderate fatty liver is associated with alterations in hepatic lipid metabolism

High blood concentrations of nonesterified fatty acids (NEFA) and altered lipid metabolism are key characteristics of fatty liver in dairy cows. In nonruminants, the mitochondrial membrane protein mitofusin 2 (MFN2) plays important roles in regulating mitochondrial function and intrahepatic lipid metabolism. Whether MFN2 is associated with hepatic lipid metabolism in dairy cows with moderate fatty liver is unknown. Therefore, to investigate changes in MFN2 expression and lipid metabolic status in dairy cows with moderate fatty liver, blood and liver samples were collected from healthy dairy cows (n = 10) and cows with moderate fatty liver (n = 10). To determine the effects of MFN2 on lipid metabolism in vitro, hepatocytes isolated from healthy calves were used for small interfering RNA-mediated silencing of MFN2 or adenovirus-mediated overexpression of MFN2 for 48 h, or treated with 0, 0.6, 1.2, or 2.4 mM NEFA for 12 h. Milk production and plasma glucose concentrations in dairy cows with moderate fatty liver were lower, but concentrations of NEFA and β-hydroxybutyrate (BHB) were greater in dairy cows with moderate fatty liver. Dairy cows with moderate fatty liver displayed hepatic lipid accumulation and lower abundance of hepatic MFN2, peroxisome proliferator-activated receptor-α (PPARα), and carnitine palmitoyltransferase 1A (CPT1A). However, sterol regulatory element-binding protein 1c (SREBP-1c), acetyl CoA carboxylase 1 (ACACA), fatty acid synthase (FASN), and diacylglycerol acyltransferase 1 (DGAT1) were more abundant in the livers of dairy cows with moderate fatty liver. In vitro, exogenous NEFA treatment upregulated abundance of SREBP-1c, ACACA, FASN, and DGAT1, and downregulated the abundance of PPARα and CPT1A. These changes were associated with greater lipid accumulation in calf hepatocytes, and MFN2 silencing aggravated this effect. In contrast, overexpression of MFN2-ameliorated exogenous NEFA-induced lipid accumulation by downregulating the abundance of SREBP-1c, ACACA, FASN, and DGAT1, and upregulating the abundance of PPARα and CPT1A in calf hepatocytes. Overall, these data suggest that one cause for the negative effect of excessive NEFA on hepatic lipid accumulation is the inhibition of MFN2. As such, these mechanisms partly explain the development of hepatic steatosis in dairy cows.

Effects of Super Nutritional Hepatic Copper Accumulation on Hepatocyte Health and Oxidative Stress in Dairy Cows.

Concerns regarding excessive hepatic copper concentrations in dairy cows have increased. The objective of this study was to determine the association of hepatic copper concentrations with evidence of liver disease. Blood and liver samples were collected at the time of slaughter in cull dairy cows (n=100). Liver samples were analyzed for copper using inductively coupled plasma mass spectrometry and crude fat using liquid-liquid extraction and gravimetry. Serum samples were analyzed for glutamate dehydrogenase, γ-glutamyltransferase, sorbitol dehydrogenase, aspartate aminotransferase activities, and bile acid concentrations. Liver samples were examined histologically for inflammation, fibrosis, and rhodanine staining. Animals were stratified by hepatic copper concentration and samples in the highest and lowest quintiles (Q5 and Q1) were evaluated for oxidative stress. Systemic indices of oxidative stress included serum reactive oxygen and nitrogen species (RONS) and total antioxidant potential (AOP). Tissue-level oxidative stress was assessed by immunohistochemistry using 4-hydroxynonenal (4HNE) and 3-nitrotyrosine (3NIT) stains to score the relative abundance and distribution of oxidized lipid and protein products, respectively. Mean hepatic copper concentration was 496.83 μg/g and median 469.72 μg/g and ranged from 70.56 to 1264.27 μg/g dry tissue. No association was found between hepatic copper concentrations and clinicopathological or histological evidence of hepatic damage or dysfunction. There was a significant increase in the amount of IHC staining of 4HNE and 3NIT in Q5 compared with Q1. Moreover, the IHC staining mirrored the distribution of the copper-specific stain rhodanine. These results demonstrate that cows with elevated hepatic copper concentrations had no evidence of active liver disease but had increased hepatic oxidative stress.

Differential effects of oilseed supplements on methane production and milk fatty acid concentrations in dairy cows

It is known that supplementing dairy cow diets with full-fat oilseeds can be used as a strategy to mitigate methane emissions, through their action on rumen fermentation. However, direct comparisons of the effect of different oil sources are very few, as are studies implementing supplementation levels that reflect what is commonly fed on commercial farms. The objective was to investigate the effect of feeding different forms of supplemental plant oils on both methane emissions and milk fatty acid (FA) profile. Four multiparous, Holstein-Friesian cows in mid-lactation were randomly allocated to one of four treatment diets in a 4×4 Latin square design with 28-day periods. Diets were fed as a total mixed ration with a 50 : 50 forage : concentrate ratio (dry matter (DM) basis) with the forage consisting of 75 : 25 maize silage : grass silage (DM). Dietary treatments were a control diet containing no supplemental fat, and three treatment diets containing extruded linseed (EL), calcium salts of palm and linseed oil (CPLO) or milled rapeseed (MR) formulated to provide each cow with an estimated 500 g additional oil/day (22 g oil/kg diet DM). Dry matter intake (DMI), milk yield, milk composition and methane production were measured at the end of each experimental period when cows were housed in respiration chambers for 4 days. There was no effect of treatment diet on DMI or milk protein or lactose concentration, but oilseed-based supplements increased milk yield compared with the control diet and milk fat concentration relative to control was reduced by 4 g/kg by supplemental EL. Feeding CPLO reduced methane production, and both linseed-based supplements decreased methane yield (by 1.8 l/kg DMI) and intensity (by 2.7 l/kg milk yield) compared with the control diet, but feeding MR had no effect on methane emission. All the fat supplements decreased milk total saturated fatty acid (SFA) concentration compared with the control, and SFA were replaced with mainly cis-9 18:1 but also trans FA (and in the case of EL and CPLO there were increases in polyunsaturated FA concentration). Supplementing dairy cow diets with these oilseed-based preparations affected milk FA profile and increased milk yield. However, only the linseed-based supplements reduced methane production, yield or intensity, whereas feeding MR had no effect.

Association of production diseases with motor activity-sensing devices and milk progesterone concentrations in dairy cows

We have previously established that the efficiency of identifying oestrus with activity-sensing devices can be compromised by common production diseases; the present study was undertaken to determine how these diseases may affect device readings. A total of 67 Holstein-Friesian cows, >20 days postpartum, were equipped with activity-sensing neck collars and pedometers, and simultaneous milk progesterone profiles were also monitored twice a week. The influences of common production stressors on maximum activity and progesterone values were analysed. Approximately 30% potential oestrus events (low progesterone value between two high values) remained unrecognised by both activity methods, and progesterone values in these animals were higher on the potential day of oestrus when both activity methods did not detect an event (0.043 ± 0.004 versus 0.029 ± 0.004 ng/mL; P = 0.03). Data from a subset of 45 cows (two events each) were subjected to mixed models and multiple regression modelling to investigate associations with production diseases. Cow motor activity was lower in lame cows. Maximum progesterone concentrations prior to oestrus increased as time postpartum and body condition score (BCS) increased. There were also fewer days of low progesterone prior to oestrus associated with increases in BCS and maximum progesterone concentrations prior to oestrus. In conclusion, lameness was associated with lower activity values, but this suppression was insufficient to account for lowered oestrus detection efficiency of either device. However, associations were identified between production diseases and progesterone profiles.

The relationship between serum anti-Müllerian hormone concentrations and fertility, and genome-wide associations for anti-Müllerian hormone in Holstein cows

The objectives of this study were to (1) evaluate factors associated with variation in circulating anti-Müllerian hormone (AMH) concentrations, (2) establish an optimum AMH threshold predictive of pregnancy to first artificial insemination (P/AI), (3) examine the relationship between AMH and fertility (P/AI, pregnancy loss between 30 and 60 d after artificial insemination, and pregnancy risk up to 250 d postpartum), and (4) identify quantitative trait loci associated with phenotypic variation of AMH concentrations in dairy cows. Serum AMH concentrations (pg/mL) were determined at 7 ± 2.4 d postpartum in 647 lactating Holstein cows (213 primiparous, 434 multiparous) from 1 research and 6 commercial dairy herds in Alberta, Canada. Of these, 589 cows were genotyped on the 26K Bovine BeadChip (Neogen Inc., Lincoln, NE) and subsequently imputed to the Illumina Bovine High Density BeadChip (Illumina, San Diego, CA) for genome-wide association analysis for variation in serum AMH concentrations. Factors associated with variation in serum AMH concentrations and the relationship between categories of AMH and aforementioned fertility outcomes were evaluated only in a subset of 460 cows that had a complete data set available. The overall mean (±standard error of the mean), median, minimum, and maximum AMH concentrations were 191.1 ± 6.3, 151.7, 13.9, and 1,879.0 pg/mL, respectively. The AMH concentrations were not associated with herd, precalving body condition score, postpartum week, and season of sampling; the lactation number, however, had a quadratic relationship with serum AMH concentrations (116.2, 204.9 204.5, and 157.9 pg/mL for first, second, third, and ≥fourth lactation, respectively). The optimum AMH threshold predictive of P/AI could not be established because the receiver operating characteristic curve analysis model was nonsignificant. Categories of AMH [low (<83.0 pg/mL; n = 92), intermediate (≥83.0 to ≤285.0 pg/mL; n = 276), and high (>285.0 pg/mL; n = 92) based on lowest 20%, intermediate 60%, and highest 20% serum AMH) had no associations with P/AI (34, 43, and 40%), pregnancy loss between 30 and 60 d after artificial insemination (20, 12, and 8%), or pregnancy risk up to 250 d postpartum. One candidate gene associated with AMH production [AMH gene on Bos taurus autosome (BTA) 7] and 4 candidate genes related to embryo development (SCAI and PPP6C genes on BTA11 and FGF18 and EEF2K genes on BTA20 and BTA25, respectively) were in linkage disequilibrium with single nucleotide polymorphisms associated with phenotypic variation in serum AMH in dairy cows.

Effect of daily milk production levels on plasma calcium, phosphorus and magnesium concentrations in dairy cows

The aim of this study was to determine the serum level of calcium (Ca), phosphorus (P) and magnesium (Mg) and hence determine the relationship and the effect of daily milk production on the mentioned essential macro elements. The metabolism and neurohumoral regulation of Ca, P and Mg are closely related, and the metabolic disorder of one of these electrolytes inevitably affects the metabolism of the other two. The study was carried out in the winter period of animal keeping and nutrition, and it included 63 Holstein-Friesian breed cows in the northern region of Bosnia and Herzegovina, aged 2-9 years in different lactation stages (1-8). The largest number of cows, eighteen of them, were in the second, third and fourth lactation stage, while nine cows were in the first lactation stage. This study was conducted on three different groups of cows corresponding to the amount of daily milk production. First was the group of lower daily milk production n=21, the second group of examined cows was the group of medium daily milk production n=23 and third was the group of higher daily milk production n=19. Ca, P and Mg were determined in blood plasma using the Beckmann spectrophotometer. By examining the obtained results and the dynamics of the tested mineral substances, we point out the different behaviour of the Ca-P relationship in correlation with the different level of daily milk produced. Although the average values ​​of both minerals are lowered with an increase in daily milk production, the analysis of single linear regression shows that there is a negative correlation between P concentration in blood plasma and the amount of daily milk produced, while for Ca it has not been established. Although the concentration of Mg in the blood plasma increases as the daily milk production increases, the analysis of single linear regression does not show a significant interconnection of these two values. Lower average values of Ca and P concentrations in the blood of cows with higher daily milk production may be associated with increased total excretion of these minerals through milk, unlike the cows which daily produced lower amounts of milk.

Vitamin A concentrations in dairy cows of Thessaloniki 's county

Avitaminosis A is stilla serius metabolic problem for cattle in Greece. The purpose of this research work was to investigate the blood vitamin A concentrations in dairy cows of Thessaloniki 's area. The research was conducted in 51 dairy cow farms; whole blood samples from 10 female adult animals per farm, as well as samples from the feedstuffs in use, were collected. Of the total 510 examined cows, 38% showed lower than normal vitamin A concentration in blood plasma (&lt;0,20 μ^ηιΐ), 15% marginal (0,20-0,24 μg/ml) and 47% normal concentration values (&gt;0,25 μg/ml). It should be noted that, of the total 510 examined cows only 7% showed extremely deficient concentration of vitamin A in blood plasma (&lt;0,05 μg/ml). The determination of total carotene concentration in feedstuffs from those farms, indicated that only the corn ensilage and the fresh grass contained the appropriate amount of carotene. The above results, in correlation with corresponding results from previous researches, indicate that there is a decrease in the percentage of cows with subnormal vitamin A concentration. This may be attributed to more frequent use of corn silage, and more systematic addition of vitamin A in concentrate feeds. This research provides evidence that some dairy cow genotypes, with high milk yields, may balance their needs only by vitamin A supplementation, it means that maybe the ration carotenes alone are no sufficient vitamin A source for these cows. Furthermore, the results of this research suggest that the absence of a regulator mechanism for the carotene concentration in the cattle blood plasma may be possible.

Prepartum daylight exposure increases serum calcium concentrations in dairy cows at the onset of lactation.

In dairy cows, hypocalcemia is caused by the sudden calcium demand by the mammary gland at the onset of lactation. Calcitriol (1,25-dihydroxy vitamin D; 1,25-VitD) increases the intestinal calcium absorption and the renal calcium reabsorption. Daylight contributes to the formation of 1,25-VitD, as it transforms 7-dehydrocholesterol into cholecalciferol, a 1,25-VitD precursor. Calving pens are usually set in quiet places where cows can stay calm and relaxed before parturition. However, those pens often have poor lighting conditions and therefore cows may become vitamin D deficient because of inadequate daylight exposure. Therefore, we have tested the hypothesis that direct daylight exposure supports the synthesis of 1,25-VitD and consequently attenuates the decline of calcium concentrations at parturition. Twenty Holstein dairy cows were randomly assigned to 2 experimental groups (daylight group, DL; and control group). Beginning on d -10 before expected parturition, both groups were placed in a standard indoor calving pen from 1700 h to 800 h. From 800 h to 1700 h cows from the DL group were moved into a contiguous open pen with direct access to daylight whereas controls remained at the standard indoor calving pen. After parturition both groups were permanently placed in an indoor calving pen until the end of the experimental period (d 30 postpartum). Blood samples were collected daily from d -10 prior to expected parturition through d 7 postpartum with an additional sample on d 30 postpartum. Milk yield was recorded at each milking during the whole experimental period. In the DL group, 25-hydroxyvitamin D (25-VitD), 1,25-VitD and total calcium concentrations around parturition were higher than in the controls. Higher parathyroid hormone concentrations were observed in the control group compared to the DL group at parturition. Pyridinoline concentrations did not differ between groups on d 1, and therefore it is assumed that the intensity of calcium transfer from the bones to the bloodstream was not affected by the increased daylight exposure. The measured plasma metabolites (β-hydroxybutyrate, fatty acids and glucose) as well as milk yield were not affected by the increased daylight exposure. In conclusion, the increased daylight exposure before parturition increased 25-VitD and 1,25-VitD concentrations, preventing a considerable decline of total calcium concentrations around parturition.

Cortisol concentration of regrown hair and hair from a previously unshorn area in dairy cows

This study determined cortisol concentrations in hair that had grown for one month and in hair from a previously unshorn area and examined the effects of calendar month, pregnancy and illness on hair cortisol concentrations in dairy cows. The study was conducted over a one-year period using 27 cows. Electric clippers were used to collect two hair samples per cow each month. The first sample (A sample) consisted of hair that had grown for one month in a pre-clipped area and the second sample (B sample) comprised all hair from a previously unshorn area. Liquid chromatography tandem mass-spectrometry was used for cortisol measurement. The overall mean concentrations for A and B samples did not differ. Cortisol concentrations of A samples were significantly higher in the winter (0.86±0.37pg/mg) than in the fall (0.67±0.33pg/mg). The hair cortisol concentration in A samples increased during pregnancy and the maximum concentration of 1.40±1.08pg/mg hair in the month of calving was significantly higher than the concentration measured in the first month (0.66±0.32pg/mg). The findings show that the effect of short-term stressors such as parturition on hair cortisol concentrations are more easily detected in hair that has grown for one month than in hair from a previously unshorn area.

Effects of dietary CLA supplementation, parity and different concentrate levels before calving on immunoglobulin G1, G2 and M concentrations in dairy cows

Peripartal dairy cows exhibit a higher susceptibility for infectious diseases, which might be linked to the negative energy balance occurring at the onset of lactation. A dietary supplementation of conjugated linoleic acids (CLA) may reduce milk fat yield and subsequently lower the energy deficit. The utilization of immunoglobulins (Ig) for colostrogenesis might impair humoral immunity in peripartal dairy cows; therefore this study investigated the effects of a CLA supplement, parity and different dietary energy levels on plasma and colostrum IgG1, IgG2 and IgM levels in dairy cows and their calves. Blood samples were collected from 64 cows from 21days before until 56days after parturition and colostrum samples for the first 3days of lactation. Plasma immunoglobulin concentrations of 19 calves were determined before colostrum uptake. Neither plasma IgG1, nor IgG2 levels were affected by CLA or dietary energy level. However, immunoglobulin levels were affected by parity. Heifers possessed the lowest IgG1 concentrations. IgG2 concentrations were highest in cows with 2 lactations prior to parturition and in heifers after parturition. Plasma IgM levels were characterized by a sharp decrease 3days prior to parturition and were scarcely affected by the feeding regimen or parity. Generally, immunoglobulin levels appear to be mostly independent from the peripartal energy balance of the cows and are not influenced by dietary CLA. However, pronounced differences among parities for IgG1 and IgG2 were revealed which should be further evaluated.

The effect of triterpenoid saponins fromSaponaria officinalison some blood hormones, metabolic parameters and fatty acid composition in dairy cows

SUMMARYAn experiment was performed to determine the effect of triterpenoid saponins from powdered root ofSaponaria officinalisL. (SO) on some blood metabolic parameters and hormone concentrations in dairy cows. Three dairy Polish Holstein-Friesian cows were used in the experiment in a 3 × 3 Latin Square arrangement. Animals were fed twice a day with a control diet and two experimental diets – a diet supplemented with either 440 or 660 g/d of the powderedS. officinalisroot (SO1 and SO2, respectively). Each of the three experimental cycles lasted for 26 days, including a 23-day adaptation period and a 3-day sample collection period. Blood samples were collected from the jugular vein from 24th to 26th day of the experiment. Total high-density lipoproteins cholesterol (HDL) and low-density lipoproteins cholesterol (LDL), as well as triglycerides, free fatty acids (FFA) and glucose, were assayed in serum. Fatty acid composition in the blood was also analysed. Moreover, concentrations of insulin, glucagon, leptin, triiodothyronine (T3) and thyroxine (T4) were measured. It was demonstrated that total and HDL-cholesterol concentrations were significantly elevated in the blood of cows treated with experimental diets; however, LDL-cholesterol remained unchanged. No concentrations of triglycerides, FFA or glucose were influenced by saponins. Two fatty acids (C16 : 0 and C16 : 1c9) were markedly reduced when SO was used, while C18 : 1t11decreased with increasing levels of SO. The significant increase of C20 : 4n-6in animals treated with SO was observed. Both saponin diets resulted in a slight increase in insulin concentration and the SO2 diet evoked an emphatic rise of glucagon concentration. The concentration of T3 also increased after consumption of the experimental diet. The current study shows for the first time that triterpenoid saponins fromS. officinaliscan alter blood parameters in ruminants. These effects seem to result from saponin-induced changes in the rumen.

The effect of corpus luteum on hormonal composition of follicular fluid from different sized follicles and their relationship to serum concentrations in dairy cows

The effect of corpus luteum on hormonal composition of follicular fluid from different sized follicles and their relationship to serum concentrations in dairy cows

Correction: Serial Non-Invasive Measurements of Dermal Carotenoid Concentrations in Dairy Cows following Recovery from Abomasal Displacement

Correction: Serial Non-Invasive Measurements of Dermal Carotenoid Concentrations in Dairy Cows following Recovery from Abomasal Displacement

Conjoint regulation of glucagon concentrations via plasma insulin and glucose in dairy cows

Insulin and glucagon are glucoregulatory hormones that contribute to glucose homeostasis. Plasma insulin is elevated during normoglycemia or hyperglycemia and acts as a suppressor of glucagon secretion. We have investigated if and how insulin and glucose contribute to the regulation of glucagon secretion through long term (48 h) elevated insulin concentrations during simultaneous hypoglycemia or euglycemia in mid-lactating dairy cows. Nineteen Holstein dairy cows were randomly assigned to 3 treatment groups: an intravenous insulin infusion (HypoG, n = 5) to decrease plasma glucose concentrations (2.5 mmol/L), a hyperinsulinemic-euglycemic clamp to study effects of insulin at simultaneously normal glucose concentrations (EuG, n = 6) and a 0.9% saline infusion (NaCl, n = 8). Plasma glucose was measured at 5-min intervals, and insulin and glucose infusion rates were adjusted accordingly. Area under the curve of hourly glucose, insulin, and glucagon concentrations on day 2 of infusion was evaluated by analysis of variance with treatments as fixed effect. Insulin infusion caused an increase of plasma insulin area under the curve (AUC)/h in HypoG (41.9 ± 8.1 mU/L) and EuG (57.8 ± 7.8 mU/L) compared with NaCl (13.9 ± 1.1 mU/L; P < 0.01). Induced hyperinsulinemia caused a decline of plasma glucose AUC/h to 2.3 ± 0.1 mmol/L in HypoG (P < 0.01), whereas plasma glucose AUC/h remained unchanged in EuG (3.8 ± 0.2 mmol/L) and NaCl (4.1 ± 0.1 mmol/L). Plasma glucagon AUC/h was lower in EuG (84.0 ± 6.3 pg/mL; P < 0.05) and elevated in HypoG (129.0 ± 7.0 pg/mL; P < 0.01) as compared with NaCl (106.1 ± 5.4 pg/mL). The results show that intravenous insulin infusion induces elevated glucagon concentrations during hypoglycemia, although the same insulin infusion reduces glucagon concentrations at simultaneously normal glucose concentrations. Thus, insulin does not generally have an inhibitory effect on glucagon concentrations. If simultaneously glucose is low and insulin is high, glucagon is upregulated to increase glucose availability. Therefore, insulin and glucose are conjoint regulatory factors of glucagon concentrations in dairy cows, and the plasma glucose status is the key factor to decide if its concentrations are increased or decreased. This regulatory effect can be important for the maintenance of glucose homeostasis if insulin secretion is upregulated by other factors than high glucose such as high plasma lipid and protein concentrations at simultaneously low glucose.

The effect of corpus luteum on hormonal composition of follicular fluid from different sized follicles and their relationship to serum concentrations in dairy cows

ObjectiveTo investigate the effect of the presence or absence of corpus luteum on hormonal composition of follicular fluid (FF) from different sized follicles and their relationship to serum concentrations in dairy cows. MethodsOvaries were collected from 30 clinically healthy adult female cows (Holstein Friesian) 4–7 years of age with clinically normal reproductive tracts after slaughtering. Blood samples were collected from the jugular vein before slaughter from each cow. The stage of the cycle in the cows was determined postmortem. The ovaries collected from per cow were classified with corpus luteum (CL+) and without corpus luteum (CL−). FF was aspirated from small (3-5 mm), medium (6-9 mm), and large (10-20 mm) follicles in CL+ and CL− ovaries. Serum and FF samples were analyzed for estradiol-17β, progesterone, testosterone, T3 and T4 concentrations. ResultsResults demonstrated that the FF concentrations of estradiol-17β, progesterone and testosterone in different sized follicles categories (small, medium and large follicles in CL+ and CL− ovaries) were significantly higher (P≤0.05) when compared with the serum. The FF concentrations of estradiol-17β and testosterone in same follicle size categories in CL+ and CL− ovaries were also significant (P<0.05). Indeed, concentrations of these hormones in the CL− ovaries were higher than those of the CL+ ovaries. However, there was a statistically significant difference between medium and large follicles for progesterone concentration in CL+ and CL− ovaries (P<0.05). There was a significant correlation between concentration of hormones in serum and FF with increased follicular diameter. ConclusionsThese results indicated that the levels of hormonal composition in the FF were related to follicular size and interestingly to the presence or absence of a corpus luteum. Indeed, the corpus luteum locally affects neighboring follicular compositions during the luteal phase of the estrous cycle in dairy cows.

Supplementation with conjugated linoleic acids extends the adiponectin deficit during early lactation in dairy cows

Decreasing insulin sensitivity (IS) in peripheral tissues allows for partitioning nutrients towards the mammary gland. In dairy cows, extensive lipid mobilization and continued insulin resistance (IR) are typical for early lactation. Adiponectin, an adipokine, promotes IS. Supplementation with conjugated linoleic acids (CLA) in rodents and humans reduces fat mass whereby IR and hyperinsulinemia may occur. In dairy cows, CLA reduce milk fat, whereas body fat, serum free fatty acids and leptin are not affected. We aimed to investigate the effects of CLA supplementation on serum and adipose tissue (AT) adiponectin concentrations in dairy cows during the lactation driven and parity modulated changes of metabolism. High yielding cows (n=33) were allocated on day 1 post partum to either 100g/day of a CLA mixture or a control fat supplement (CON) until day 182 post partum. Blood and subcutaneous (sc) AT (AT) biopsy samples were collected until day 252 post partum to measure adiponectin. Serum adiponectin decreased from day 21 pre partum reaching a nadir at calving and thereafter increased gradually. The distribution of adiponectin molecular weight forms was neither affected by time, parity nor treatment. Cows receiving CLA had decreased serum adiponectin concentrations whereby primiparous cows responded about 4weeks earlier than multiparous cows. The time course of adiponectin concentrations in sc AT (corrected for residual blood) was similar to serum concentrations, without differences between CLA and CON. CLA supplementation attenuated the post partum increase of circulating adiponectin thus acting towards prolongation of peripartal IR and drain of nutrients towards the mammary gland.

Association between β-hydroxybutyrate concentration at surgery for correction of left-displaced abomasum in dairy cows and removal from the herd after surgery

To estimate the sensitivity, specificity, likelihood ratios, and predictive values of blood β-hydroxybutyrate (BHB) concentrations in dairy cows immediately prior to surgical correction of left-displaced abomasum (LDA) for determining associations between BHB concentration and removal from the herd ≤ 30 days after surgery and to evaluate postsurgical risk of removal for cows with the BHB concentration that had highest sensitivity and specificity for predicting this outcome. Prospective cohort study. 136 dairy cows with LDA diagnosed between 5 and 30 days in lactation (ie, days in milk). Blood BHB concentration was measured immediately prior to surgery. All cows underwent surgical correction of LDA while standing. Follow-up information was obtained ≥ 30 days after surgery. Receiver operating characteristic curves were used to estimate a critical threshold value for BHB concentration that was associated with removal from the herd, and this value was used in Poisson regression to estimate risk ratio for the same outcome. While controlling for parity in the model, cows with a BHB concentration < 1.2 mmol/L at the time of LDA surgery were 2.5 times as likely (95% confidence interval, 1.3 to 5.0) to be removed from the herd ≤ 30 days after surgery, compared with cows that had a BHB concentration ≥ 1.2 mmol/L. Results indicated that blood BHB concentration in dairy cows undergoing surgical correction of LDA may potentially be a useful prognostic indicator for the likelihood of removal from the herd ≤ 30 days after surgery. Further research is needed to evaluate other risk factors that may be associated with this outcome.