Concentrates For Dairy Cows Research Articles

Effect of Oral Calcium Propionate on Blood Calcium and Energy Metabolite Concentrations in Dairy Cows with Dystocia Fed a Prepartum Anionic Diet

Results from research on the calcium and energy status of cows affected with dystocia have not been conclusive. We hypothesize that during early post-partum (pp), similar to cows with retained placenta and uterine prolapse, cows with dystocia develop subclinical hypocalcemia, as well as ketosis. Therefore, the objectives of this study were : (1) to describe the total blood calcium (tCa), betahydroxybutyrate (BOHB) and non-esterified free fatty acid (NEFA) concentrations in blood during the first 12 days pp in dairy cows with dystocia, 2) to determine if an oral calcium propionate drench at calving and 72 hours later improves blood calcium concentration and energy status.

Evaluation of a Hand-Held Meter for Cowside Evaluation of Blood Beta-Hydroxybutyrate and Glucose Concentrations in Dairy Cows

Ketosis, defined as blood beta-hydroxybutyrate (BHBA) concentrations greater than 1,400 umol/1, is an important problem in dairy herds. Prompt and accurate detection of ketosis may lessen its negative effects on milk yield and reproduction, and may help prevent subsequent displaced abomasum. Cowside tests are necessary for prompt diagnosis and treatment of ketosis; however, existing cowside urine or milk ketone tests are limited by their relatively low sensitivity (about 80%) compared to blood BHBA (the gold standard test for ketosis). Cowside blood glucose tests have not been commonly used but could be useful in helping clinicians determine if glucose treatments are indicated for early lactation cows with an unknown diagnosis or that have already been treated for ketosis. The objectives of this study were to evaluate the correlation of BHBA and glucose results from the hand-held meter with laboratory analysis results, and to evaluate the sensitivity and specificity of the hand-held meter for determining BHBA and glucose concentrations above established cut-points.

Ghrelin and orotic acid increased in subclinical mastitis

Hormone ghrelin and orotic acid accelerate wound healing as well as controlling inflammation and immunity. We have, therefore, investigated the serum and milk levels of ghrelin and orotic acid in dairy cows with (n = 21) or without (n = 21) subclinical mastitis. Acylated and des-acylated ghrelin as well as orotic acid concentration were detected by using high performance liquid chromatography (HPLC). The results revealed that ghrelin level in milk and serum was significantly higher in dairy cows with subclinical mastitis than that of dairy cows without subclinical mastitis. This was also the case when the orotic acid concentrations in dairy cows with subclinical mastitis were compared with those dairy cows without subclinical mastitis. In conclusion, ghrelin and orotic acid occur in particularly high concentrations in subclinical mastitis, and might, therefore, be required in greater amounts for tissue repair and may be also used as a indicator for subclinical mastitis.

A comparison of the effects of parenteral and oral administration of supplementary vitamin E on plasma vitamin E concentrations in dairy cows at different stages of lactation

As a result of research conducted in the US, recommendations for dry cow vitamin E intakes have increased seven fold there, however there has been no change to recommendations in the UK. As part of a larger study comparing the impact of existing UK and new US recommended vitamin E intakes on the health and fertility of commercial dairy cows in the UK, a study was set up to investigate the effect of route of supplementation and stage of lactation, over a 21 day period, on the response to mega-supplementation of cattle receiving supposedly adequate vitamin E. The study assessed the response of dry, peak lactation and mid lactation cows to in-feed or parenteral vitamin E supplementation (7 animals per treatment/lactation stage group) by measuring plasma and milk vitamin E concentrations, blood glutathione peroxidase (GSH-Px) activity and milk yields over a 21 day period. Plasma vitamin E concentrations were significantly influenced by a time, stage and treatment interaction (P = 0.046). Both dry and lactating animals had significantly higher plasma vitamin E concentrations at some time points in the parenteral supplemented cows compared to the in-feed supplementated animals (P ≤ 0.011 and P < 0.01, respectively). Milk vitamin E concentrations did not significantly differ between lactation stages but treatment had a significant effect on concentrations (P < 0.008) when lactation stage was removed from the model. There was no significant difference in milk yield between treatment groups. A significant relationship between plasma and milk vitamin E concentrations was only found in the parenterally supplemented cows (r = 0.435, P < 0.001). In cattle with intakes greater than the ARC recommendations, measurement of plasma vitamin E concentration may be of limited value in determining whether there has been a response to supplementation. The relationship between plasma and milk vitamin E concentrations is too poor for milk vitamin E concentrations to be used as a proxy for plasma vitamin E.

Effect of Mastitis on Milk Perchlorate Concentrations in Dairy Cows

Recent surveys have identified the presence of perchlorate, a natural compound and environmental contaminant, in forages and dairy milk. The ingestion of perchlorate is of concern because of its ability to competitively inhibit iodide uptake by the thyroid and to impair synthesis of thyroid hormones. A recent study established that milk perchlorate concentrations in cattle highly correlate with perchlorate intake. However, there is evidence that up to 80% of dietary perchlorate is metabolized in clinically healthy cows, thereby restricting the available transfer of ingested perchlorate into milk. The influence of mastitis on milk perchlorate levels, where there is an increase in mammary vascular permeability and an influx of blood-derived components into milk, remains unknown. The present study examined the effect of experimentally induced mastitis on milk perchlorate levels in cows receiving normal and perchlorate-supplemented diets. Over a 12-d period, cows were ruminally infused with 1 L/d of water or water containing 8mg of perchlorate. Five days after the initiation of ruminal infusions, experimental mastitis was induced by the intramammary infusion of 100μg of bacterial lipopolysaccharide (LPS). Contralateral quarters infused with phosphate-buffered saline served as controls. A significant reduction in milk perchlorate concentration was observed in the LPS-challenged glands of animals ruminally infused with either water or perchlorate. In control glands, milk perchlorate concentrations remained constant throughout the study. A strong negative correlation was identified between mammary vascular permeability and milk perchlorate concentrations in LPS-infused glands. These findings, in the context of a recently published study, suggest that an active transport process is operative in the establishment of a perchlorate concentration gradient across the blood–mammary gland interface, and that increases in mammary epithelial and vascular endothelial permeability lead to a net outflow of milk perchlorate. The overall finding that mastitis results in lower milk perchlorate concentrations suggests that changes in udder health do not necessitate increased screening of milk for perchlorate.

Use of barley fibre and wet distillers’ solubles as feedstuffs for Ayrshire dairy cows

The experiment was conducted to study use of barley fibre and wet distillers’ solubles (WDS), by-products from integrated starch–ethanol production, as feed in dairy cows’ diet. Barley fibre is a fibrous by-product with high content of neutral detergent fibre and low content of starch. Wet distillers’ solubles is the non-fermentable residue after distillation of ethanol. It has a high crude protein content with a high rumen degradability. Ayrshire cows, 12 multiparous and 12 primiparous, were divided into 6 blocks of 4 cows according to parity and calving date. Cows in each block were fed four different total mixed rations (TMR) according to a balanced 4 × 4 Latin Square design within a 2 × 2 factorial arrangement of the treatments. Treatments were two different energy sources (barley (B) or barley + barley fibre (BF, 1:1)) with two protein sources (rapeseed meal (RSM) or RSM + WDS). Thus, the treatments were B, B + WDS, BF and BF + WDS. Grass silage was the forage (400 g/kg diet dry matter). On the B + WDS and BF + WDS diets, the amount of WDS in TMR was 120 g/kg dry matter (DM). The crude protein content of the diets was 180 g/kg DM. Replacing half of the barley grain with barley fibre increased (P<0.01) milk yield (32.2 kg/day versus 33.0 kg/day) but had no effect on DM intake (DMI) (21.5 kg/day versus 21.7 kg/day). Replacement caused a small, but significant (P<0.001) decrease in milk protein content (35.3 g/kg versus 34.2 g/kg) with no change in protein yield. Inclusion of barley fibre in the diet had no effect on milk fat content but changed (P<0.001) its fatty acid profile by increasing the proportion of unsaturated fatty acids and conjugated linoleic acid. Replacing part of the RSM with WDS decreased performance of cows by reducing (P<0.001) DMI (21.0 kg/day versus 22.1 kg/day), milk yield (31.7 kg/day versus 33.6 kg/day) and yields of milk components. Inclusion of WDS in the diet decreased efficiency of N utilization. Barley fibre was a good fibrous component in concentrates for dairy cows’ TMR, but WDS was an inferior protein feed to RSM as a feed for lactating Ayrshire dairy cows.

Metabolic variables and plasma leptin concentrations in dairy cows exhibiting reproductive cycle abnormalities identified through milk progesterone monitoring during the post partum period

We have used milk progesterone analysis to monitor reproductive function in lactating dairy cows and have then related this reproductive function to a variety of metabolic variables. Monitoring of cows ( n = 41) during the period of onset of luteal function (first milk progesterone reading > 5 ng/ml) revealed that delayed onset was associated with increased milk yield and greater loss of body weight and body condition but was not related to plasma metabolite or leptin concentrations. Further monitoring of reproductive function in these 41 cows and an additional 33 cows (total n = 74) during the mating period (from weeks 6 to 14 post partum) identified reproductive cycle abnormalities in 29 (39.2% of animals). The occurrence of cycle abnormalities was associated with increased milk yield ( P < 0.05), elevated plasma beta hydroxybutyrate ( P < 0.05) and reduced plasma leptin ( P < 0.01) concentrations as well as a lower ( P < 0.05) rate of gain of body weight and condition score but was not associated with plasma urea or glucose concentrations. Furthermore, cows exhibiting cycle abnormalities had a longer ( P < 0.01) interval to first service and a smaller percentage had conceived by 100 days post partum (34.5% versus 66.7%; P < 0.01). These results provide further evidence that impaired reproductive function during the post partum period in dairy cows is caused by a poor energy status and not elevated urea concentrations. Reduced plasma leptin concentrations in animals suffering reproductive dysfunction further supports this view.

Blood melatonin and prolactin concentrations in dairy cows exposed to 60 Hz electric and magnetic fields during 8 h photoperiods.

Two experiments were conducted to test the hypothesis that electric and magnetic field (EMF) exposure may result in endocrine responses similar to those observed in animals exposed to long days. In the first experiment, 16 lactating, pregnant Holstein cows were assigned to two replicates according to a crossover design with treatment switchback. All animals were confined to wooden metabolic cages and maintained under short day photoperiods (8 h light/16 h dark). Treated animals were exposed to a vertical electric field of 10 kV/m and a horizontal magnetic field of 30 microT (EMF) for 16 h/day for 4 weeks. In a second, similar experiment, 16 nonlactating, nonpregnant Holstein cows subjected to short days were exposed to EMF, using a similar protocol, for periods corresponding to the duration of one estrous cycle. In the first experiment, circulating MLT concentrations during the light period showed a small numerical decrease during EMF exposure (P < .05). Least-square means for the 8 h light period were 9.9 versus 12.4 pg/ml, SE = 1.3. Melatonin concentrations during the dark period were not affected by the treatment. A similar trend was observed in the second experiment, where MLT concentrations during the light period tended to be lower (8.8 pg/ml vs. 16.3 pg/ml, P < .06) in the EMF exposed group, and no effects were observed during the dark period. Plasma prolactin (PRL) was increased in the EMF exposed group (16.6 vs. 12.7 ng/ml, P < .02) in the first experiment. In the second experiment, the overall PRL concentrations found were lower, and the mean plasma PRL concentration was not affected by treatment. These experiments provide evidence that EMF exposure may modify the response of dairy cows to photoperiod.

Plasma mineral and energy metabolite concentrations in dairy cows fed an anionic prepartum diet that did or did not have retained fetal membranes after parturition

To compare plasma total calcium, phosphorus, magnesium, nonesterified fatty acids (NEFA), beta hydroxy butyrate (BHB), and glucose concentrations in parturient dairy cows that were fed an anionic prepartum diet between those with and without retained fetal membranes (RFM) at 24 hours after parturition. 152 Holstein cows that calved during October through December of 1997 All cows were fed an anionic prepartum diet. Blood sample was taken within 6 hours after parturition from randomly selected cows. Thirty-nine cows had a diagnosis of RFM at 24 hours after parturition; 113 were not affected with RFM. At calving, body condition score (BCS; 1 [thin] to 5 [obese]), parity, and calving difficulty score were recorded. Plasma calcium, phosphorus, magnesium, NEFA, BHB, and glucose concentrations were compared between cows with or without RFM. Cows with RFM had significantly lower plasma calcium concentration soon after calving, compared with cows without RFM. Cows with a parity of > or = 3 had significantly lower plasma concentrations of calcium and higher concentrations of magnesium, compared with cows with a parity of 1 or 2. Cows with a BCS of > or = 3.25 at calving had significantly higher plasma concentrations of BHB than cows with a BCS of 2.75 to 3.0. Cows with dystocia had significantly higher plasma concentrations of glucose, compared with cows without dystocia. In parturient cows fed a prepartum anionic diet, those with RFM have lower plasma calcium concentrations than cows without RFM, although this association does not prove a cause-effect relationship.

The effect of cereal grain-based supplements on blood B-hydroxy-butyrate concentrations in dairy cows in a pasture-based system

The effect of cereal grain-based supplements on blood B-hydroxy-butyrate concentrations in dairy cows in a pasture-based system

Growth hormone induced alterations of leptin serum concentrations in dairy cows as measured by a novel enzyme immunoassay

The present knowledge on the interrelationship between leptin and the somatotropic axis in livestock, in particular the effects of growth hormone (GH) treatment on leptin secretion is inconsistent. We therefore aimed to characterise GH-induced alterations of blood leptin concentrations in dairy cows and first developed and validated a competitive enzyme immunoassay (EIA). The assay is valid in cattle, sheep, goat, pig and in horses. Lactating cows were injected once with 500 mg depot-formulated bovine GH and blood samples were drawn every second day 2 weeks before and 4 weeks after the GH injections and were assayed for leptin and for insulin-like growth factor-1 (IGF-1). Leptin concentrations were decreased in response to the GH treatment solely in pregnant cows ( p<0.05), whereas IGF-1 concentrations were increased independently of pregnancy status. In conclusion, the response of leptin blood concentrations towards GH treatment in lactating cows might depend from endocrine and metabolic cues related to pregnancy.

Effect of Lipopolysaccharide Infusion on Serum Macromineral and Vitamin D Concentrations in Dairy Cows

Four multiparous lactating cows (175 to 220 d in milk) were used in a 4×4 Latin square design to assess the effects of four doses (0.0, 0.5, 1.0, 1.5μg/kg of body weight) of lipopolysaccharide (LPS; Escherichia coli 0111:B4) on circulating concentrations of macrominerals and vitamin D metabolites. Treatments were dissolved in 100ml of sterile saline and infused intravenously over a period of 100min. Blood was sampled immediately before infusion (0h), at 60-min intervals for 8h, and at 24 and 48h postinfusion. Vitamin D metabolites were analyzed in samples collected at 0, 2, 6, 24, and 48h only. Serum Ca and P concentrations decreased after LPS infusion, but there was no effect on serum magnesium concentration. Plasma 25-OH vitamin D3 and 1,25-(OH)2 vitamin D3 were not affected by LPS infusion; however, when analyzed as 0 vs. all other doses of LPS combined, there was a tendency for plasma 1,25-(OH)2 vitamin D3 concentration to decrease when cows were infused with LPS. The inflammatory response elicited by LPS altered plasma macromineral concentrations, a result that may have important implications for calcium homeostasis and metabolic health of lactating dairy cows.

Metabolite and ionic composition of follicular fluid from different-sized follicles and their relationship to serum concentrations in dairy cows

Metabolic changes in blood serum may be reflected in the biochemical composition of follicular fluid and could indirectly influence oocyte quality. The purpose of this study was to examine the biochemical composition of follicular fluid harvested from different-sized follicles and its relationship with that of blood serum in dairy cattle. Following slaughter, blood samples were collected from dairy cows ( n=30) and follicular fluid aspirated from three size classes of non-atretic follicles (<4 mm, 6–8 mm and >10 mm diameter). Samples remained independent between cows and between size classes within cows. Serum and follicular fluid samples were assayed using commercial clinical and photometric chemistry assays for ions (sodium, potassium and chloride) and metabolites (glucose, β-hydroxybutyrate (β-OHB), lactate, urea, total protein, triglycerides, non-esterified fatty acids (NEFA) and total cholesterol). Results showed that follicular fluid concentrations of glucose, β-OHB and total cholesterol increased from small to large follicles and decreased for potassium, chloride, lactate, urea and triglycerides. There was a significant concentration gradient for all variables between their levels in serum and follicular fluid ( P<0.05). Significant correlations were observed for chloride ( r=0.40), glucose ( r=0.56), β-OHB ( r=0.85), urea ( r=0.95) and total protein ( r=0.60) for all three follicle size classes and for triglycerides ( r=0.43), NEFA ( r=0.50) and total cholesterol ( r=0.42) for large follicles ( P<0.05). The results from the present study suggest that the oocyte and the granulosa cells of dairy cows grow and mature in a biochemical environment that changes from small to large follicles. Furthermore, the significant correlation between the composition of serum and follicular fluid for the above-mentioned metabolites suggests that metabolic changes in serum levels will be reflected in the follicular fluid and, therefore, may affect the quality of both the oocyte and the granulosa cells.

Metabolic profiles and plasma leptin concentrations in lactating and non-lactating mares

The present knowledge on the interrelationship between leptin and the somatotropic axis in livestock, in particular the effects of growth hormone (GH) treatment on leptin secretion is inconsistent. We therefore aimed to characterise GH-induced alterations of blood leptin concentrations in dairy cows and first developed and validated a competitive enzyme immunoassay (EIA). The assay is valid in cattle, sheep, goat, pig and in horses. Lactating cows were injected once with 500 mg depot-formulated bovine GH and blood samples were drawn every second day 2 weeks before and 4 weeks after the GH injections and were assayed for leptin and for insulin-like growth factor-1 (IGF-1). Leptin concentrations were decreased in response to the GH treatment solely in pregnant cows (p<0.05), whereas IGF-1 concentrations were increased independently of pregnancy status. In conclusion, the response of leptin blood concentrations towards GH treatment in lactating cows might depend from endocrine and metabolic cues related to pregnancy.

Relationship between blood selenium concentration or glutathione peroxidase activity, and milk selenium concentrations in New Zealand dairy cows

Aim: To determine the relationships between blood selenium (Se) concentrations or glutathione peroxidase activity (GSH-Px), and milk Se concentrations in dairy cows. Methods: Seventy-two Friesian dairy cows were either untreated or injected with 0.5, 1.0 or 2.0 mg Se/kg liveweight as barium selenate (BaSeO4) formulations, resulting in 6 groups of animals with mean blood Se concentrations that varied from 212 to 2272 nmol/l. Milk samples were collected on Days 104 and 188, and blood samples were collected prior to treatment and on Days 41, 76, 104, 188, 244, and 292 after Se injection. Results: Significant quadratic relationships between blood Se and milk Se concentrations, as well as blood GSH-Px activity and milk Se concentrations, were evident at Days 104 and 188. Using combined data, these were represented by the equations: milk Se = 27.3 + 0.073 blood Se -0.00001 (blood Se)2; R2=0.79, p<0.005, and; milk Se = 34.8 + 4.99 GSH-Px -0.068 (GSHPx)2; R2=0.79, p<0.005. Conclusions: The Se status of dairy cows can be assessed from milk Se concentrations. Clinical significance: Bulk-tank milk Se concentrations could be evaluated as a method to assess the Se status of dairy herds.

Plasma oxytocin and cortisol concentrations in dairy cows in relation to feeding duration and rumen fill

The aim of this study was to investigate if the release of oxytocin and cortisol were different depending on levels of oral manipulation with feed or rumen fill in dairy cows. Blood samples and behavior of 12 rumen-fistulated cows were analyzed in 2 consecutive years during morning and afternoon periods when the cows were subjected to either (A) long duration of oral manipulation of feed with low rumen fill or (B) short duration of oral manipulation of feed but with filled rumen. The response areas under the curve for oxytocin in both years were larger in A than in B in the afternoons. There were peaks in oxytocin release at milking in the afternoon in both treatments. In B, the oxytocin concentration was higher after than before feeding, higher in B than in A after the non-oral rumen filling, and higher in B after than before the non-oral rumen filling in Year 1. The level of cortisol was higher in B than in A in the morning, lower in both treatments before than after milking in the afternoon, and there was a tendency for the cortisol level to be higher in A than in B after oral feeding. The B cows spent a shorter time eating and the A cows spent a shorter time ruminating. This study indicates that a long duration of oral manipulation of feed in cows, may, per se be linked to higher oxytocin but lower cortisol levels, compared with shorter oral feeding time and filled rumen.

Technical note: forms and route of vitamin C supplementation for cows.

The purpose of this study was to compare the effect of multiple oral supplementation of two forms of vitamin C on plasma ascorbic acid concentrations in dairy cows. Vitamin C was administrated at the rate of 40 g/d during a 5-d period. The supplements were vitamin C in the form of a fine powder and vitamin C coated with ethyl cellulose. In addition, another group of cows provided with vitamin C in the form of fine powder through an abomasal fistula was enrolled in the study. The effect of vitamin C supplementation was assessed by the change in plasma ascorbic acid concentrations during a 5-d period of vitamin C supplementation. A tendency existed for cows that were dosed with vitamin C in the abomasum to have higher ascorbic acid than cows supplemented orally. In the abomasum-dosed cows, plasma ascorbic acid value varied between 3.6 and 4.4 micrograms/ml; the maximum ascorbic acid content was 4.4 micrograms/ml at 54 h. Cows dosed orally with vitamin C coated with ethyl cellulose had higher plasma ascorbic acid concentrations than did cows that received vitamin C in the form of fine powder. In the former group, the maximum ascorbic acid concentration occurred at 30 h after dosing (5 micrograms/ml).

Relationship between Days to Postpartum First Ovulation and Days to Reaching Steady Range of Metabolite Concentrations in Dairy Cows

Transitional multiparous dairy cows were used to estimate the relationships between the interval from parturition to the first ovulation (1st-OV), and the interval from parturition to the first day when the plasma metabolite concentration reached the steady range (within two standard deviations from the mean value for the post-ovulational 2 weeks). Blood samples were collected from 13 Holstein dairy cows 4 times every week from 14 days prepartum to about 60 days postpartum in order to analyze plasma concentrations of progesterone and the following eight metabolites: glucose, ketone bodies, free fatty acids (FFA), urea nitrogen (UN), free cholesterol, cholesterol ester, glutamic-oxaloacetic transaminase (GOT), and glutamic-pyruvic transaminase (GPT). The interval to 1st-OV averaged 25.6 ± 8.7 days, and correlated respectively with the intervals to the days when plasma concentrations of almost all the metabolites, except GPT and UN, reached the steady range. We concluded that the interval to the 1st-OV of dairy cows is closely related to the interval to the steady range of metabolites concerned with the energy status, but not protein intake. Additionally, the interval to the 1st-OV also correlated significantly with the mean concentration of free cholesterol before the 1st-OV.

Effects of Electric and Magnetic Fields on Nocturnal Melatonin Concentrations in Dairy Cows

Sixteen multiparous, pregnant, lactating Holstein cows (weighing 600±50kg, at 184.8±52 d of lactation, and at 101.9±43 d of gestation) were confined to wooden metabolism cages and exposed to a vertical electric field of 10 kV/m and a uniform horizontal magnetic field of 30 μT. The trial was conducted using a switchback statistical design. Cows were divided into two sequence groups of 8 cows each. One sequence group was exposed for three periods of 28 d each. The electric and magnetic fields were off during the first period, on during the second period, and off during the final period. The second sequence group was exposed for three periods also, but the activity of the fields was reversed (on during the first period, off during the second period, and on during the third period). On d 25 of each exposure period, blood samples were obtained every 0.5h for 14h starting at 1700h to determine melatonin concentration. Nocturnal melatonin concentrations did not show any variation that could be attributed to exposure to electric and magnetic fields.

Influence of Se status on milk Se concentrations in dairy cows

Changes in blood and milk selenium (Se) concentrations were measured in dairy cattle grazing Se‐deficient pastures compared with animals grazing the same pasture but given either an intraruminal Se bolus or a barium selenate injection. The Se supplementation significantly increased and maintained the blood Se concentrations (e.g., 342 versus 1113 nmol/1) over 190–265 days during the lactation and also increased milk Se concentrations 2‐fold (e.g., 77.2 versus 132.3 nmol/1).