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Biomedical subjects

A Malestein

Publications and source records attributed to A Malestein.

18 recordsLinked to original sources
PubMed1995

[Cobalt supply to ruminants, a bottleneck?].

On some dairy farms the supply of cobalt was expected to be adequate given the soil data and the composition of the ration. However cows on these farms produced less milk than expected and their condition was poor considering their ration and milk yield. The milk lactose content was less than 4.5%. The cows produced more milk after they were given extra cobalt (5.5 mg/day). The animals, condition improved, the milk lactose content rose, and the animals ate more dry matter than previously. A marked increase in the potassium content of the grass silage possibly depressed the availability of cobalt and caused vitamin B12 deficiency. This needs further investigation.

Animals↗
PubMed1992

[Necessity and method of administering minerals in cattle feed].

The soil of cattle farms can differ markedly, thus making it impossible to guarantee that animals receive an adequate supply of minerals. Mineral deficits are expected first in animals grazing pastures on sand, peat and iron-rich clay soils. The quality of the rations can also differ, which underlies the necessity of mineral supplementation. Supplementation is especially necessary when fewer concentrates are given or when more single products are given. Different formulations are often needed on one farm, depending on the feed available and the needs of the animals. In general, too little attention is paid in practice to animals that are not given concentrates. There are different ways of meeting the requirements of the different groups. On the basis of a thorough investigation of farm practices and rations, it can be determined whether supplementation is necessary, and if necessary, how this can be best achieved cheaply and effectively.

Animal Feed↗
PubMed1991

[Milk fever].

Explore the source record for details and available documents.

Animal Feed↗
PubMed1990

On the pathogenesis of abortion in acute nitrite toxicosis of pregnant dairy cows.

Six cows, 220 to 260 d pregnant, were used to study possible abortifacient effects of absorbed nitrite. Maternal and fetal bloodvessels were catheterized. Nitrite was infused intravenously (i.v.) for 30 minutes on Days 1, 3 and 5, commencing at least 5 d postcatheteration. The dose used was 7, 9.5 and 12 mg NO(2)(-)/kg bodyweight, respectively. Nitrite caused a dose-related (P < 0.05) conversion of maternal hemoglobin (Hb) into methemoglobin (MHb); a 30 to 50% decrease of mean arterial bloodpressure; an increase in heart rate, with dose-related recovery periods; and a decrease in partial oxygen tension (PO(2)) of maternal blood. Maternal partial carbon dioxide tension (PCO(2)), pH and electromyographic activity of the uterus were unchanged. Fetal changes included a small increase in MHb content, variable changes in heart rate (tachycardia and bradycardia), and decreases in fetal PO(2), with considerable differences between animals. All calves were born alive. Three cows calved early, 2 to 3 d after the highest nitrite dose. The hematological and cardiovascular data suggest that these three fetuses experienced a more serious hypoxemic stress than the other fetuses.

Journal Article↗
PubMed1990

Effects of an inadequate dietary intake of magnesium on osteogenesis in dairy cows during the dry period.

The osteogenic activity in the rib bones of 33 dairy cows (14 of parity 1 or 2, and 19 of parity 3 or more) during their last two months of pregnancy, and the effects upon it of a deficient supply of dietary magnesium, were studied by means of intravenous infusions of the fluorochromes oxytetracycline hydrochloride, calcein and chlortetracycline given nine weeks, five weeks and one week, respectively, before the expected time of parturition. Seven weeks before this date the cows' ration was changed to one containing either 0.22 per cent magnesium (LMg) or 0.82 per cent magnesium (HMg) in the dry matter, and the potassium content of both rations was increased to approximately 4.1 per cent in the dry matter to reduce the absorption of magnesium. Four of the 10 LMg-high parity cows showed signs of periparturient hypocalcaemia. A significant decrease in the number of labelled osteons towards parturition was demonstrated in both the low parity (P less than 0.05) and high parity cows (P less than 0.001). The mean bone apposition rate in high parity cows was significantly lower (P less than 0.001) than in low parity cows. The different levels of magnesium in the diets of the cows had no significant effects on the numbers of osteons which were labelled nine weeks, five weeks or one week before parturition, or on the numbers of osteons which took more than one label or on the bone apposition rate. These results show that in these cows the rate of bone remodelling decreased as parturition approached.

Animals↗
PubMed1988

[Inadequate milk production in cattle caused by an incorrect diet; an example from practice].

The milk production per cow on a dairy farm did not increase to any appreciable extent during the past few years. Moreover, when a number of cattle were found not to be pregnant, this suggested mineral deficiency to the livestock owner. The diet of the animals was therefore examined at his request and some advice was offered on this basis. These recommendations resulted in an increase of the production per cow in a standard herd, averaging 3.2 units, during the following year. The production of milk fat and milk protein showed an average daily increase of 146 g per animal. Mineral deficiency as a causative factor was considered to be unlikely.

Animal Feed↗
PubMed1987

Influence of a deficient supply of magnesium during the dry period on the rate of calcium mobilisation by dairy cows at parturition.

The influence of a deficient magnesium supply during the dry period on the ability of dairy cows to mobilise calcium at parturition was investigated. The daily rations pre-partum consisted of 6 kg grass hay, and 4 kg concentrates containing either 1.58 per cent magnesium (HMg) or 0.22 per cent magnesium (LMg). Nine cows of parity one to six received the LMg diet and 10 cows of parity one to seven the HMg diet. Both rations provided 1.40 times maintenance on an energy basis and contained 4 per cent potassium in the dry matter. Throughout the dry period the mean concentration of magnesium in the plasma of the LMg group was significantly lower than in the HMg group and at parturition the mean plasma concentrations were 0.65 mmol litre-1 and 1.16 mmol litre-1, respectively. After parturition two cows in the LMg group showed clinical signs of hypocalcaemia but none of the HMg group did so. Cows of the LMg group had a lower mean rate of calcium mobilisation (0.27 mmol min-1) than those of the HMg group (0.34 mmol min-1) but the difference could not be explained by differences in bone turnover as reflected by urinary hydroxyproline excretion. Such a reduced rate of calcium mobilisation may be a contributory factor in the high incidence of milk fever in some herds fed inadequate magnesium in the dry period.

Animal Feed↗
PubMed1986

Effects of low and high calcium intake prepartum on calcium mobilization rate around parturition in dairy cows.

Forty-one dairy cows were fed a low (LCa-13 g/d) and a high (HCa-83.5 g/d) calcium ration in the 8 weeks prior to parturition and the effect on the Ca mobilization rate around parturition was studied. Plasma Ca values were stable in the LCa group around parturition. In the older cows of the HCa group a very slight decrease in the mean plasma Ca was observed: 2.58 mmol/l at 12-36 h ante partum decreased to 2.38 mmol/l at parturition. Hypocalcaemia, which commonly occurs around parturition, did not occur in 40 of the cows. A subclinical hypocalcaemia (1.8 mmol/l) occurred in one cow (parity 10) from the HCa group. To assess the efficiency of Ca mobilization, a severe hypocalcaemia (1.0 mmol/l) with clinical signs was induced by means of Na2EDTA infusion (0.90 mmol/min), starting at 10 h post-partum. The older cows in the LCa group required more Na2EDTA than those in the HCa group. Higher urinary hydroxyproline excretion in the week before parturition in the LCa than in the HCa group suggested a higher bone turnover. Plasma PTH levels around parturition were not significantly different between the groups. The amount of colostrum milked out in the first 10 h post-partum did not influence Ca homeostasis around parturition. The results contradict those of many other experiments in which hypocalcaemia was observed in cows ingesting high levels of Ca. It is concluded that the restricted feed intake prepartum possibly had a favourable effect on Ca homeostasis.

Animals↗
PubMed1986

Influence of prepartum calcium intake on calcium mobilization rate around parturition in dairy cows fed at a high prepartum feeding level.

The influence of a low and a high prepartum calcium (Ca) intake on Ca mobilization rate around parturition was studied in 44 dairy cows fed a ration sufficient for 1.90 times maintenance requirements during the dry period. The plasma Ca level declined on the day of parturition in the group fed the low Ca intake (LCa: 26.4 g/d) as well as in the group fed the high Ca intake (HCa: 87.2 g/d). Plasma Ca levels of the HCa group were lower at parturition, and in this group 1 cow had milk fever after parturition. In the HCa group 6 cows had a plasma Ca level less than or equal to 2.0 mmol/l at parturition and/or 10 h post-partum (pp), versus 1 cow in the LCa group. Na2EDTA was intravenously infused at 10 h pp to induce hypocalcaemia to a level of plasma Ca not bound to EDTA of approximately 1.0 mmol/l. The LCa groups tended to require more Na2EDTA than the HCa groups, however the difference was significant only in the younger cows. After the Na2EDTA infusion 7 cows of the HCa group and 1 of the LCa group did not recover spontaneously and needed to be treated. The mean plasma PTH levels of the LCa group ante-partum were slightly higher than those of the HCa group. The Ca level of the prepartum ration did not influence urinary hydroxyproline excretion, which suggests that the Ca intake of 26.4 g/d was too high to stimulate bone turnover. Comparison of the present results with those of an earlier experiment in which the prepartum Ca intake at a low feeding level (1.12 times maintenance) was studied, led to the conclusion that higher prepartum feed intake has a clear negative influence on Ca homeostasis around parturition.

Animal Nutritional Physiological Phenomena↗
PubMed1983

[Does the supply of magnesium affect the feed intake in ruminants?].

The magnesium balance is in a state of equilibrium in dairy cattle when the daily excretion of Mg in the urine is a least 2.5 g. (= 100 mM). When the daily urinary output is 25 l, this is equivalent to a concentration of at least 4 mM (= 100 mg/l). The production of milk was inadequate on a number of dairy farms, which was associated with loss of appetite of the cows. The concentration of Mg in the urine of various cows was found to be too low on these farms. When additional magnesium was supplied, the feed intake was restored within a few days and the milk production also increased. The finding that an inadequate supply of Mg may have a negative effect on the feed intake was supported by some findings reported in the literature.

Animal Feed↗
PubMed1983

[Supply of magnesium in cattle].

The supply of magnesium is determined by the concentration of Mg in the ration, the absorption coefficient of Mg in the fodder and by the feed intake. In lactating cows, the supply of Mg usually will be sufficient when concentrates contain 5 g. or 7 g. of Mg per kilogram during the housing and grazing period respectively. For dry cows fed roughage only a daily supplement of 50 g. of MgO per cow may be required.

Animal Feed↗
PubMed1981

[Guide to feeding of cattle during the grazing period (author's transl].

Grass is high grade roughage. Its energy content (appr. 1650 kcal. NE of dry matter) approximates that of concentrates. As a rule, the protein content of dry matter is much higher than the minimum required for growth or milk production, and this may have an adverse effect on the utilization of Cu and Mg. The structural value of grass is another factor to bear in mind in feeding dairy cows, the more so when concentrates or other non- or less structural products are also fed. Of the mineral constituents the elements Ng, Na, Cu, Co and j require most attention. This is not the case when more than appr. 4 kg of concentrate daily are fed to cows. However, supplying Mg often continues to cause concern. The daily dry matter intake from grass is appr. 2.0-2.5 per cent of body weight, but this varies with the season, climate and indoor or outdoor feeding. Fully grazing cows can produce appr. 25 kg of milk in the spring and appr. 18 kg in the autumn. When the cows are kept indoors at night or kept at zero grazing, the production level is somewhat lower (see Table under 2.3). For cows showing a higher production concentrates are therefore required. To prevent too great an intake of intestinal parasites in young animals (calves), grazing aftermath is the most effective method, though it is not easy to carry out in every case. For stale or dry cows the feed intake from grass usually is too high. This may result in fat cows as well as an increased risk of milk fever.

Animal Feed↗
PubMed1980

Nitrate poisoning in cattle. 4. The effect of nitrite dosing during parturition on the oxygen capacity of maternal blood and the oxygen supply to the unborn calf.

In a series of experiments the effect of administering KNO2 was studied, during parturition, on the capability of oxygen transport of maternal blood and on oxygen transfer to foetal blood. The following blood parameters were analysed, MHb percentage, pO2, O2-saturation, pH, pCO2, and (NO2) in maternal arterial blood (carotid art.) and venous blood (jugular vein) and in foetal arterial blood (umbilical art.) and venous blood (umbilical vein). The relative O2-saturation was calculated from the estimated O2-saturation by multiplying with the factor Hb (mmol/l) minus MHb (mmol/l), divided by Hb (mmol/l). In addition, blood pressure in the carotid artery, heart rate, and respiration rate in the dam were continuously recorded for some hours. A dosage of 9 to 12 mg of NO1/kg body weight intravenously or of 30 mg of NO2/kg body weight orally to the dam caused much higher MHb percentages and NO2 contents in the maternal blood than in the foetal blood. In maternal blood the ratio of NO2 content to MHb percentage was proportional to that in foetal blood. In the arterial blood, MHb percentages were almost as high as in the venous blood. After administering of nitrite, relative O2-saturation dropped simultaneously with the increase in methaemoglobin. Nitrite treatment caused a drop in the maternal blood pressure; heart rate and respiration rate increased. O2-saturation in the blood in the umbilical vein was much lower in the animals with nitrite treatment than in those without. These experimental results show clearly that the oxygen capacity of the blood decreases after nitrite treatment. In pregnant cows the oxygen supply to the foetus will be adversely affected after nitrate intake, especially by the lower oxygen transfer via the placenta, though hardly at all by methaemoglobin formation in the foetal blood. When the oxygen transfer to the foetal blood decreases too sharply, intra-uterine death and ultimately abortion may result.

Animals↗
PubMed1977

Nutrition of dairy cows in late pregnancy during the housing period and its relationship to health and milk yields.

The relationship between the plane of nutrition in dry cows and heifers during late pregnancy on the one hand and health and milk production on the other is discussed. It is concluded from findings reported in the literature as well as from personal observations that when the animals are in normal condition, a plane of nutrition in excess of that required for maintenance plus from 5 to 10 kg. of milk will not enhance the milk yield but will increase the risk of milk fever, acetonaemia, digestive disorders, laminitis, udder problems and reproductive failure. Finally, suggestions are made regarding the plane of nutrition (concentrates) during late pregnancy and early lactation.

Acetone↗