Milk Mineral Research Articles

Technical note: Development and validation of a new method for the quantification of soluble and micellar calcium, magnesium, and potassium in milk

Milk mineral content is a key trait for its role in dairy processes such as cheese-making, its use as source of minerals for newborns, and for all traits involving salt-protein interactions. This study investigated a new method for measuring mineral partition between soluble and micellar fractions in bovine milk after rennet coagulation. A new whey dilution step was added to correct the quantification bias due to whey trapped in curd and excluded volume. Moreover, the proposed method allowed the quantification of the diffusible volume after milk coagulation. Milk mineral content and concentration in whey, and diluted whey were quantified by acid digestion and inductively coupled plasma optical emission spectrometry. The repeatability of the method for micellar Ca, Mg, and K was between 2.07 and 8.96%, whereas reproducibility ranged from 4.01 to 9.44%. Recovery of total milk minerals over 3 spiking levels ranged from 92 to 97%. The proposed method provided an accurate estimation of micellar and soluble minerals in milk, and curd diffusible volume.

Subclinical mastitis (SCM) and proinflammatory cytokines are associated with mineral and trace element concentrations in human breast milk

The possibility that either subclinical mastitis (SCM), an inflammatory condition of the breast, or elevations in breast milk proinflammatory cytokines alter breast milk mineral and trace element composition in humans has not been investigated. In this cross-sectional study, breast milk samples (n=108) were collected from Guatemalan Mam-Mayan mothers at one of three stages of lactation (transitional, early and established), and categorized as SCM (Na:K >0.6) or non-SCM (Na:K ≤0.6). Milk concentrations of 12 minerals (calcium, copper, iron, magnesium, manganese, phosphorus, potassium, rubidium, selenium, sodium, strontium, and zinc) and 4 proinflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) were measured by inductively coupled plasma mass spectrometry (ICP-MS), Lachat analyzer or Luminex multiplex bead cytokine assay. SCM was more prevalent during transitional (30%) than early (15.6%) and established (8.9%) lactation. Analysis of variance revealed that breast milk minerals differed by stage of lactation and SCM status. Breast milk minerals with the exception of magnesium were lower in established lactation, whereas SCM was associated with higher selenium and lower phosphorus. Regression models that controlled for lactation stage also confirmed that SCM was associated with lower milk phosphorus and higher milk selenium concentrations. Furthermore, cytokine concentrations were independently associated with several mineral concentrations: IL-1β with higher phosphorus and iron, IL-6 with higher calcium, magnesium, copper and manganese, IL-8 with higher calcium and zinc, and TNF-α with lower iron and manganese. We conclude that milk mineral and trace element concentrations are affected not only by the presence of SCM but also by proinflammatory cytokines in breast milk.

Phenotypic characterisation of major mineral composition predicted by mid-infrared spectroscopy in cow milk

Population-level phenotyping is, for some traits, hardly achievable due to limitation of reference analyses. Mid-infrared spectroscopy (MIRS) is a quick and cost-effective laboratory technique allowing the prediction of innovative milk quality features on a large scale. The present study aimed at investigating factors associated with milk Ca, K, Mg, Na and P contents predicted by MIRS models on a large multi-breed spectral data set of 123,240 test-day records. Two dairy (Holstein–Friesian and Brown Swiss) and two dual-purpose (Simmental and Alpine Grey) cattle breeds were considered. Sources of variation of predicted milk mineral contents were studied using linear mixed models, including the fixed effects of breed, month of sampling, stage of lactation, parity and interactions between the main effects. Random factors were herd nested within breed, cow nested within breed and the residual. Calcium content was greater in milk of dual-purpose than dairy cattle breeds. Simmental cows produced milk with the greatest content of Ca and Na, and milk of Holstein-Friesian had the lowest P content. Variation of content of Ca, Mg, Na and P throughout lactations exhibited an opposite trend to that of milk yield, with the lowest values around the peak of lactation. On the other hand, K content mirrored the trend of milk yield. Multiparous cows had lower content of milk minerals, with the exception of Na, compared with first parity animals. Environmental factors identified in the present study can be considered for within-breed genetic evaluation to adjust records of milk mineral contents for these effects.

Interaction of potassium carbonate and soybean oil supplementation on performance of early-lactation dairy cows fed a high-concentrate diet

Potassium carbonate supplementation is known to improve milk fat synthesis and to modify milk mineral composition in dairy cows. The objective of the current experiment was to evaluate the effect of K2CO3 on production performance, biohydrogenation of fatty acids (FA), and mineral composition of milk in early-lactation dairy cows fed a high-concentrate diet with or without soybean oil (SBO), as a source of polyunsaturated FA. Twenty-eight ruminally fistulated Holstein cows were used in a randomized complete block design. The experiment lasted 33 d, including a 5-d pretreatment collection period used as a covariate. Experimental treatments were arranged as a 2 × 2 factorial with 0 or 1.5% K2CO3 and with 0 or 2% SBO, and balanced to contain 40% forage (57% corn silage + 43% grass silage) and 60% concentrate. Preplanned orthogonal contrasts were used to assess the effects of K2CO3, SBO, and their interaction. Feeding K2CO3 did not affect milk yield, but tended to increase 4% fat-corrected milk and fat yield when combined with SBO. However, adding SBO to diets increased milk yield. Dietary K2CO3 supplementation did not affect milk fat concentration of trans-10 18:1 or any other identified biohydrogenation intermediates. Soybean oil supplementation decreased milk fat concentration of C16 and de novo synthesized FA, and increased preformed FA. Among the other effects of SBO supplementation observed, concentrations of cis-9,trans-11 18:2 increased, as well as most of the cis and trans isomers of 18:1 and 18:0. Milk urea N decreased in cows fed K2CO3 as compared with unsupplemented diets. A positive relation was established between milk Cl concentration and milk yield, suggesting that the equilibrium of this ion is linked to the efficiency of lactogenesis. The effect of K2CO3 on this mineral equilibrium in the mammary gland remains to be established. Overall, results have shown that potential effect of K2CO3 on milk fat synthesis is dependent on the levels of dietary polyunsaturated FA.

The effects of a lipid-based nutrient supplement and antiretroviral therapy in a randomized controlled trial on iron, copper, and zinc in milk from HIV-infected Malawian mothers and associations with maternal and infant biomarkers.

We evaluated effects of antiretroviral (ARV) therapy and lipid‐based nutrient supplements (LNSs) on iron, copper, and zinc in milk of exclusively breastfeeding HIV‐infected Malawian mothers and their correlations with maternal and infant biomarkers. Human milk and blood at 2, 6, and 24 weeks post‐partum and blood during pregnancy (≤30 weeks gestation) were collected from 535 mothers/infant‐pairs in the Breastfeeding, Antiretrovirals, and Nutrition study. The participants received ARV, LNS, ARV and LNS, or no intervention from 0 to 28 weeks post‐partum. ARVs negatively affected copper and zinc milk concentrations, but only at 2 weeks, whereas LNS had no effect. Among all treatment groups, approximately 80–90% of copper and zinc and <50% of iron concentrations met the current adequate intake for infants at 2 weeks and only 1–19% at 24 weeks. Pregnancy haemoglobin was negatively correlated with milk iron at 2 and 6 weeks (r = −.18, p < .02 for both). The associations of the milk minerals with each other were the strongest correlations observed (r = .11–.47, p < .05 for all); none were found with infant biomarkers. At 2 weeks, moderately anaemic women produced milk higher in iron when ferritin was higher or TfR lower. At 6 weeks, higher maternal α‐1‐acid glycoprotein and C‐reactive protein were associated with higher milk minerals in mildly anaemic women. Infant TfR was lower when milk mineral concentrations were higher at 6 weeks and when mothers were moderately anaemic during pregnancy. ARV affects copper and zinc milk concentrations in early lactation, and maternal haemoglobin during pregnancy and lactation could influence the association between milk minerals and maternal and infant iron status and biomarkers of inflammation.

Comparative Study of Concentration of Some Minerals in Milk and Blood Plasma of Sheep and Goats Native and Foreign During Post-Partum Period under Climatic Conditions of Upper Egypt

Comparative Study of Concentration of Some Minerals in Milk and Blood Plasma of Sheep and Goats Native and Foreign During Post-Partum Period under Climatic Conditions of Upper Egypt

Effect of multiple births on Jamunapari goat milk minerals under field and farm rearing conditions

The study was conducted at the Central Institute for Research on Goats, Makhdoom, Mathura; under the division nutrition feed resources and products technology for the study of farm rearing condition. A total of 479 milk samples were collected from field and farm rearing condition 222 single (field 28 and farm 194), twins 230 (field 66 and farm 164) and triplets 27 (field 08 and farm 19) milk samples. The overall average calcium content of all above samples in all rearing and births was 0.1455±0.0019 per cent. Phosphorus content was significantly greater in farm samples than field rearing samples in all multiple births. Potassium percentage in the milk of Jamunapari goat breed under field and farm rearing conditions in single, twins and triplets birth was found to be 0.113±0.0008 and 0.113±0.0008, 0.111±0.0007 and 0.111±0.0008 and 0.107±0.0008 and 0.109±0.0008 respectively. The highest magnesium, chloride and selenium content were observed in single birth samples under field as well as farm rearing samples. Multiple births had conspicuous effects on milk quality of goats under study.

Commercial Mineral Enhanced Dairy By-Products as Sodium Replacers, Antioxidants and Calcium Fortifiers in Sausages

Sausages are perceived as high in Na and with a too high Na:K ratio. Frankfurter type sausages are regarded as important contributors of sodium in the diet and thereby of health risks. Surplus products from the dairy industry are various mineral powders enriched in either potassium, calcium, or phosphate and include various amounts of lactose. Sausages were produced at 3 sodium levels (equivalent to 13, 15, and 17 g NaCl/kg sausage) using 4 different milk ingredients (a dried skimmed milk powder, a calcium enriched milk powder, a potassium enriched powder, and a lactose enriched powder). The sausages with added calcium and potassium enriched milk powders resulted in the hardest sausages when compared at the same sodium level. Milk mineral addition also produced whiter and less red sausages. No effect on rancidity after 6 wk at chill (4 °C) storage was observed by adding milk minerals, when compared with adding dried skimmed milk powder. A significant advantage of using these milk minerals in sausages is that the Na:K ratio can be reduced from an unhealthy (in this study 36) to a far healthier ratio ( ̴ 2) with limited or no taste changes. High additions of milk calcium (6 g/kg), where Ca-phosphates prevail, added as milk mineral, had no influence on sensory bitterness or aftertaste as typically observed for CaCl2 additions. Ca additions to sausages are presently presumed to be an advantage with respect to human nutrition.

Retinol, α-tocopherol, and selected minerals in breast milk of lactating women with full-term infants in South Korea.

BACKGROUND/OBJECTIVESThis study was performed to measure fat-soluble vitamins and minerals in breast milk of Korean lactating mothers who exclusively breastfed their babies.SUBJECTS/METHODSBreast milk samples were collected from 334 mothers. Concentrations of retinol and α-tocopherol were analyzed by high performance liquid chromatography ultraviolet spectrometry while concentrations of minerals were measured by inductively coupled plasma optical emission spectrometry.RESULTSRetinol and α-tocopherol contents of breast milk were 39.58 ± 19.64 µg/dL and 0.23 ± 0.13 mg/dL, respectively. Average sodium, potassium, calcium, phosphorus, and magnesium levels in breast milk were 11.11 ± 5.16, 38.56 ± 9.01, 27.87 ± 6.10, 13.56 ± 3.30, and 3.05 ± 0.65 mg/dL, respectively. Contents of trace elements such as iron, zinc, copper, and manganese were 40.26 ± 46.21, 98.40 ± 62.47, 24.09 ± 9.03, and 0.90 ± 1.63 µg/dL, respectively. Fat-soluble vitamin concentration was positively correlated with total fat in milk samples, but no significant differences were observed in levels of retinol, α-tocopherol, or minerals based on whether or not lactating women were taking dietary supplements.CONCLUSIONSMicronutrient contents of breast milk samples from Korean lactating women were comparable to those of other nations. Retinol and α-tocopherol levels were correlated and also with total fat in breast milk.

Concentrations of Major and Minor Elements in Cow’s Milk at Najaf Province

Milk is a very important human nutritive since their consumption has increased in recent years. The aim of this paper was to determine the content of major and minor elements in different milk samples. The current study included measuring the percentages of fat, protein, lactose and solids non fat. Also the present study involved determination some essential minerals in milk, such as measured concentration of calcium, magnesium, phosphorus, sodium, potassium, chloride, and iron. Milk was sampled in March 2016 on ten farms in the Najaf Province directly into plastic bottles (to avoid contamination). The reported data showed that the essential contents of milk of selected farms were have a significant difference and P &gt; 0.05

0873 Mineral balances including TMR, drinking water and assay minerals in the milk

Drinking water for dairy animals or manure for soil applications can be both a source of mineral nutrients and toxic substances. Commercial dairy production systems (grazing or indoors) are evolving to a larger scale, with more cows per farm and milk production per cow. Including assayed concentrations of minerals in the diet, drinking water and milk could improve the accuracy of calculations of herd or pen mineral balances. The aim of this presentation is to discuss mineral contents in TMR, water, and milk on mineral balances and excretion in lactating dairy cows. A mineral balance study in California on 40 dairies with low total salts (TS) drinking water for lactating dairy animals (0.2 to 1.5 g TS/L) was performed to compare TMR mineral content with the NRC requirement, with and without including minerals in drinking water, and the average NRC values for milk mineral concentrations to assayed minerals in the bulk tank milk. Most TMR minerals were in excess of NRC requirements. When including minerals in drinking water, Mg, Na, Cl, S, and Cu increased TMR median mineral contents by about 5% (ranging from 3.6% for S to 7% for Na). The assayed values of minerals in milk were lower than NRC averages (i.e., Mg, 49%; Na, 58%; Cu, 295%; and Fe, 525%). Estimated excretions of minerals via manure varied substantially across farms. Farms in the 10th percentile had estimated mineral excretions via manure 2 to 3 times less than those in the 90th. For example, daily K median excretion was 321 g/cow, from 240 (10th) to 425 g/cow (90th percentile), daily Na excretion varied from 69 (10th) to 168 g/cow (90th percentile) with a median of almost 100 g. Median Cu and Zn excretions were 417 and 1700 mg/cow per day, but Cu excretion increased more than 3 times and Zn more than 2.5 times from the 10th to 90th percentiles. Estimates of dairy farm mineral balances should be based on assayed mineral concentrations in dietary ingredients, drinking water, and milk. Accurate estimates of mineral balance can then be used to manage excess minerals (diet and manure) and improve animal mineral nutrition, nutrient management plans, and soil mineral nutrition.

Phenotypic characterisation of milk technological traits, protein fractions, and major mineral and fatty acid composition of Burlina cattle breed

The aim of the present study was to characterise milk of Burlina local cattle breed for traits of technological and nutritional relevance, such as milk coagulation properties (MCP), and protein, major mineral and fatty acid (FA) composition. Burlina is mainly reared in mountain areas of Veneto Region (Italy) and it has been inserted in conservation plans aiming to avoid biodiversity loss and marginal pasture areas abandonment. Eighty-one individual milk samples were collected in four farms. Milk coagulation properties were determined using Formagraph, and protein, mineral and FA composition were analysed in high performance liquid chromatography, inductively coupled plasma optical emission spectrometry and gas chromatography, respectively. Results evidenced good protein percentage (3.38%) and considerable casein content (28.89 mg/mL), as well as a desirable FA profile, with ω-6 to ω-3 ratio of 4.04. Somatic cell score, averaging 3.13, is a trait that should be enhanced through the improvement of farm management. This would have positive effects on MCP. Among milk minerals, the most and less abundant were K (1493.53 mg/kg) and Mg (110.07 mg/kg), respectively. Overall, herd, parity and lactation stage explained moderate to low variation of the studied traits. Results of the present study could be useful to valorise Burlina local breed and preserve biodiversity in marginal areas.

Relationship between breast milk composition and weight growth velocity of infants fed with exclusive breast milk

To study the effect of breast milk composition on weight growth velocity of infants fed with exclusive breast milk. One hundred and thirty-eight full-term singleton infants who received regular follow-up visits and fed with exclusive breast milk and their mothers were recruited. Body height, weight and head circumference of these infants were measured at regular visits. Z scores were used to evaluate growth velocity. The subjects were classified into a failure to thrive group (ΔZ scores≤-0.67), a poor growth group (-0.67<ΔZ scores<0) and a normal control group (ΔZ scores≥0). The samples of mature breast milk were collected for composition analysis. The differences in the levels of the protein, fats, energy, carbohydrates and minerals in breast milk were compared among the three groups. ΔZ scores for weight in the failure to thrive and poor growth groups were lower than in the normal control group (P<0.05). There was no significant difference in the levels of protein, fats and energy in breast milk among the failure to thrive, poor growth and normal control groups. However, the levels of carbohydrates and minerals in both the failure to thrive and poor growth groups were lower than in the normal control group (P<0.05). Weight growth velocity of infants can be affected by the composition of breast milk to a certain degree in a short period. In order to maintain a good weight growth velocity of infants, mothers should have a balanced diet to improve the quality of breast milk.

The effect of ewe mineral status on the lambs mineral supply

The aim of our study is to examine the mineral status of Tsigai ewes and their lambs based on wool mineral content, and the relationship between ewes wool and milk mineral content and the lamb wool mineral concentration. Ten Tsigai sheep nursing single lamb was randomly selected on the 6–10th day of lactation. Sampling was carried out in March. Wool samples free of visible contamination were obtained from the withers of the ewes and the lambs using bended scissors. Approximately 10 ml of milk samples were collected by hand milking. Ca, Mg, Na, Cu, S, P, Se and Zn content were determined by ICP-OES (Perkin-Elmer, Optima 3300 DV). Statistical analyses were carried out by SAS (SAS Institute Inc., Cary, NC) GLM procedure. Wool mineral content did not show deficient supply in case of ewes. Young lamb’s wool mineral composition is distinct from those measured in adult ewes. This fact and the lack of significant correlation between ewe and lamb mineral status indicates strictly regulated mineral passage through placenta.

Short communication: Variations in major mineral contents of Mediterranean buffalo milk and application of Fourier-transform infrared spectroscopy for their prediction.

The aims of this study were (1) to assess variability in the major mineral components of buffalo milk, (2) to estimate the effect of certain environmental sources of variation on the major minerals during lactation, and (3) to investigate the possibility of using Fourier-transform infrared (FTIR) spectroscopy as an indirect, noninvasive tool for routine prediction of the mineral content of buffalo milk. A total of 173 buffaloes reared in 5 herds were sampled once during the morning milking. Milk samples were analyzed for Ca, P, K, and Mg contents within 3h of sample collection using inductively coupled plasma optical emission spectrometry. A Milkoscan FT2 (Foss, Hillerød, Denmark) was used to acquire milk spectra over the spectral range from 5,000 to 900 wavenumber/cm. Prediction models were built using a partial least square approach, and cross-validation was used to assess the prediction accuracy of FTIR. Prediction models were validated using a 4-fold random cross-validation, thus dividing the calibration-test set in 4 folds, using one of them to check the results (prediction models) and the remaining 3 to develop the calibration models. Buffalo milk minerals averaged 162, 117, 86, and 14.4mg/dL of milk for Ca, P, K, and Mg, respectively. Herd and days in milk were the most important sources of variation in the traits investigated. Parity slightly affected only Ca content. Coefficients of determination of cross-validation between the FTIR-predicted and the measured values were 0.71, 0.70, and 0.72 for Ca, Mg, and P, respectively, whereas prediction accuracy was lower for K (0.55). Our findings reveal FTIR to be an unsuitable tool when milk mineral content needs to be predicted with high accuracy. Predictions may play a role as indicator traits in selective breeding (if the additive genetic correlation between FTIR predictions and measures of milk minerals is high enough) or in monitoring the milk of buffalo populations for dairy industry purposes.

Predictive ability of mid-infrared spectroscopy for major mineral composition and coagulation traits of bovine milk by using the uninformative variable selection algorithm.

Milk minerals and coagulation properties are important for both consumers and processors, and they can aid in increasing milk added value. However, large-scale monitoring of these traits is hampered by expensive and time-consuming reference analyses. The objective of the present study was to develop prediction models for major mineral contents (Ca, K, Mg, Na, and P) and milk coagulation properties (MCP: rennet coagulation time, curd-firming time, and curd firmness) using mid-infrared spectroscopy. Individual milk samples (n=923) of Holstein-Friesian, Brown Swiss, Alpine Grey, and Simmental cows were collected from single-breed herds between January and December 2014. Reference analysis for the determination of both mineral contents and MCP was undertaken with standardized methods. For each milk sample, the mid-infrared spectrum in the range from 900 to 5,000cm(-1) was stored. Prediction models were calibrated using partial least squares regression coupled with a wavenumber selection technique called uninformative variable elimination, to improve model accuracy, and validated both internally and externally. The average reduction of wavenumbers used in partial least squares regression was 80%, which was accompanied by an average increment of 20% of the explained variance in external validation. The proportion of explained variance in external validation was about 70% for P, K, Ca, and Mg, and it was lower (40%) for Na. Milk coagulation properties prediction models explained between 54% (rennet coagulation time) and 56% (curd-firming time) of the total variance in external validation. The ratio of standard deviation of each trait to the respective root mean square error of prediction, which is an indicator of the predictive ability of an equation, suggested that the developed models might be effective for screening and collection of milk minerals and coagulation properties at the population level. Although prediction equations were not accurate enough to be proposed for analytic purposes, mid-infrared spectroscopy predictions could be evaluated as phenotypic information to genetically improve milk minerals and MCP on a large scale.

Impact of stages of lactation on the minerals of Jakhrana goat milk under field and farm rearing condition

Goat milk as a source for minerals nutrition is an often overlooked benefit of this dairy treat. In fact, when it comes to calcium, potassium and selenium, goat milk is a real champ. It seems, however, that the amount of mineral is not the only nutritional factor. The study was conducted at the central institute for research on goats, Makhdoom, Mathura; under the division nutrition feed resources and products technology for the study of farm rearing condition. Milk samples were collected from Jakhrana goat under the farm and field rearing condition. Field samples were collected from different villages. The overall average calcium content was 0.146±0.0019 per cent. Phosphorus percentage in the milk of Jakhrana goat breed under field and farm rearing conditions in early, middle and late lactation 0.122±0.0011 and 0.124±0.0010 and 0.124±0.0012 and 0.126±0.0011 and 0.126±0.0010 and 0.128±0.0011 per cent, respectively. The potassium content in the milk of Jakhrana goat breed under field and farm rearing samples in early, middle and late lactation was 0.112±0.0006 and 0.113±0.0009, 0.111±0.0009 and 0.112±0.0008 and 0.110±0.0009 and 0.111±0.0008 per cent, respectively. The overall average magnesium per cent in all above samples either field or farm rearing conditions in all stage of lactation was 0.0146±0.00015. Chloride content in Jakhrana goat breed indicated that the effect of stage of lactation under field and farm rearing condition was found to be 0.100±0.00058 and 0.103±0.00050 and 0.104±0.00059 and 0.107±0.00054 and 0.114±0.00061 and 0.114±0.00054 in early, middle and late lactation, respectively. The selenium percentage in the milk of Jakhrana goat breed under field and farm rearing conditions in early, middle and late lactation was found to be 0.01681±0.000053 and 0.01641±0.000058, 0.01695±0.000055 and 0.01666±0.000060 and 0.01709±0.000057 and 0.01690±0.000060, respectively. The overall average selenium content was a 0.01667±0.000058. Stages of lactation had conspicuous effects on milk quality of goats under study.

Milk protein composition and stability changes affected by iron in water sources

Water makes up more than 80% of the total weight of milk. However, the influence of water chemistry on the milk proteome has not been extensively studied. The objective was to evaluate interaction of water-sourced iron (low, medium, and high levels) on milk proteome and implications on milk oxidative state and mineral content. Protein composition, oxidative stability, and mineral composition of milk were investigated under conditions of iron ingestion through bovine drinking water (infused) as well as direct iron addition to commercial milk in 2 studies. Four ruminally cannulated cows each received aqueous infusions (based on water consumption of 100L) of 0, 2, 5, and 12.5mg/L Fe2+ as ferrous lactate, resulting in doses of 0, 200, 500 or 1,250mg of Fe/d, in a 4×4Latin square design for a 14-d period. For comparison, ferrous sulfate solution was directly added into commercial retail milk at the same concentrations: control (0mg of Fe/L), low (2mg of Fe/L), medium (5mg of Fe/L), and high (12.5mg of Fe/L). Two-dimensional electrophoresis coupled with matrix-assisted laser desorption/ionization–tandem time-of-flight (MALDI-TOF/TOF) high-resolution tandem mass spectrometry analysis was applied to characterize milk protein composition. Oxidative stability of milk was evaluated by the thiobarbituric acid reactive substances (TBARS) assay for malondialdehyde, and mineral content was measured by inductively coupled plasma mass spectrometry. For milk from both abomasal infusion of ferrous lactate and direct addition of ferrous sulfate, an iron concentration as low as 2mg of Fe/L was able to cause oxidative stress in dairy cattle and infused milk, respectively. Abomasal infusion affected both caseins and whey proteins in the milk, whereas direct addition mainly influenced caseins. Although abomasal iron infusion did not significantly affect oxidation state and mineral balance (except iron), it induced oxidized off-flavor and partial degradation of whey proteins. Direct iron addition to milk led to lipid oxidation during storage at 4°C. Oxidation level was positively associated with the concentration of added iron. Minerals (Mg, P, Na, K, Ca, Zn) in milk were not affected by the added iron in milk. This study indicated that a small amount of iron contamination in bovine drinking water at the farm or incidental iron addition from potable water sources causes oxidation, affects milk protein composition and stability, and affects final milk quality.

Effects of different strategies of mineral supplementation (marine algae alone or combined with rumen boluses) in organic dairy systems.

This study was designed to evaluate the effect of marine algae supplementation alone or in combination with a regular mineral supplement (rumen boluses) to improve the mineral status in organic dairy cattle and their effect on the milk mineral composition, milk production, composition (% of fat and protein) and quality (SCC). Thirty-two Holstein Friesian lactating cows were randomly selected and assigned to the algae (A), boluses (B), algae+boluses (AB) and control group (C). For the algae groups (A, AB), a supplement composed of Sea Lettuce (80%), Japanese Wireweed (17.5%) and Furbelows (2.5%) was formulated to be given to the cows at the rate of 100g/animal per day (A1) for the length of 4weeks. In the second half of the experiment (weeks 5-8), the algae mixture was reformulated and the proportion of Furbelows was increased from 2.5% to 5.0% with a subsequent decrease of Lettuce to 77.5% (A2). In the boluses group (B), each cow received 2 boluses after calving. Blood (serum) and milk samples were collected at 2 and 4week intervals, respectively, and analysed for trace element concentrations by ICP-MS. Information related to the milk composition and SCC during a 305-day lactation for each animal were obtained from the Dairy Records Management System. The supplementation with algae, boluses or the combination of both treatments showed a statistically significant effect on the iodine (algae), selenium (boluses) and cobalt (algae+boluses) status of the animals. In milk, treatments had a statistical significant increase on iodine, and a tendency to increase selenium concentrations. The assayed algae mixture combined with another source of selenium could be an effective tool to improve the mineral status in serum and milk.

Effect of genotype and lactation on milk urea nitrogen, blood urea nitrogen and milk composition of dairy cows

This study was aimed to evaluate milk urea nitrogen (MUN) of cows considering variations in dietary nutrition, genetic quality and lactation yield which will be helpful to develop practical feeding guidelines for dairy cows based on MUN. A total of forty dairy cows consisting 20 native and 20 crossbred milking cows were selected in Sonaimuri, Noakhali in winter season to know the daily feed availability to cows. Feed, milk and blood samples were collected and analyzed. The dry matter intake of the local and crossbred cows were 2.58 and 2.74 (g/100 kg live weight respectively) and they did not show statistical variation (p&lt;0.05). Metabolizable energy (ME) and protein intake showed significantly higher values in crossbred (85 MJ/day and 815 g/day) compared to local (40 MJ/day and 395 g/day) cows in winter season (p&gt;0.05). Live weight, body condition score and milk yield and MUN varied significantly between genotypes although blood urea nitrogen (BUN) value did not differ significantly. Strong correlation between lactose and protein percentage was observed in both the lactations in local cows. Milk minerals are negatively correlated with protein, SnF and minerals in first lactation whereas moderate to strong relation was observed in second lactation with those parameters. Milk constituents didn’t show any difference between local &amp; crossbred cows. Strong correlation between milk protein and lactose with SnF were observed in both local and crossbred cows in first lactation stage. BUN value showed a moderate correlation between milk yields of local cows. The results revealed that genotype and lactation have no effect on BUN although MUN value showed significant difference between local and crossbred cows.Bangladesh J. of Livestock Res. 19(1-2): 74-84, Jan-Dec 2012