The association of non-clotting of cow's milk with scour in the single suckled beef calf

An apparent correlation between the clotting ability of cows milk and the prevalence of scour in suckling calves was investigated. Fifty-eight per cent of the milk samples of mothers of scouring single suckled calves showed impaired clotting ability. While the cause of this remains unknown there appears to be a link with diet. The poor clotting ability is probably a contributory factor in the aetiology of scour in the suckler calf, as the abnormality has only been seen in the milk from mothers of scouring calves.

The effect of freezing and pasteurizing bovine milk on its ability to protect neonatal guinea-pigs against colonization of the small intestine by Escherichia coli

The ability of frequent feeding of bovine milk diets to prevent the colonization of the small intestines of newborn guinea-pigs with orally inoculated Escherichia coli was tested. At 3--4 days small intestinal samples from suckled controls were frequently sterile or were colonized with only very low numbers of Esch. coli. No bovine milk diet exhibited a significant "protective" effect but the diets could, however, be ranged in order of effectiveness in decreasing colonization by Esch. coli. Raw, fresh bovine milk was best, followed by milk pasteurized at 56 degrees or 63 degrees, then boiled milk; frozen milk was the worst. Because of this last finding, neither the bacteriostatic lactoferrin-dependent activity nor the lactoperoxidase could be correlated with the ability to decrease the colonization of the small intestines by Esch. coli.

Transport of 3H-TRH from plasma to rat milk: accumulation and slow degradation in milk and presence of unaltered hormone in gastric content of pups

10 microCi 3H-TRH was administered intravenously to lactating rats 14 days after delivery. The total radioactivity of plasma and mild equalized about 25 min after injection and increased continually in milk during the 2-hour study. The percentage of activity bound to specific TRH antibody was the same in extracts of plasma and mild (about 60% of standard binding) throughout the experiment. Besides milk, the radioactivity was also accumulated in pituitary, thyroid, kidney and liver; the tissue:plasma ratio being 2:4 2 h after injection. The presence of 3H-TRH in milk extracts was also confirmed by paper chromatography (butanol-acetic acid-water-ethylacetate, 1:1:1:1) and electrophoresis (in pyridine acetate buffer, pH 5.8). TRH-degrading activity, representing about one fifth of that in plasma, was found in rat milk in vitro by means of paper chromatography and electrophoresis. The gastric contents of suckling pups after injection of 3H-TRH were also analyzed. The total radioactivity increased from 30 to 60 min after the injection. The percentage reacting with the specific TRH antibody in extracts of gastric contents was the same as that in plasma and milk and did not change throughout the 2 h of experiment. Our results show one-way transport of TRH from plasma to milk, low TRH-degrading activity of milk and passage of unaltered neurohormone from plasma to milk and stomach of suckling. The gastric content does not have a deteriorating effect on TRH. We suppose that the presence of accumulated TRH in maternal milk could be some biological significance in suckling, in which the plasma TRH-degrading system is lacking.

The influence of availability of free school milk on the height of children in England and Scotland

The effect is investigated of availability of free school milk on height gain in one year of six- and seven-year-old primary schoolchildren in England and Scotland, using data collected annually from 1972 to 1976. The height gain of children for whom milk was available for the whole year of observation was compared with that of children who had no milk. Out of 16 sex-country-year-specific analyses for children from manual social classes only, 13 showed no significant evidence of greater height gain in children who had milk. Comparison of children from Social Classes IV and V (semi-skilled and unskilled) showed no greater increase in height for those who had milk, nor was there a difference in height gain between manual social class children according to the number of glasses of milk they drank a day at home or at school. We concluded that, given the standard of living at the time of the survey, the drinking of free school milk did not increase the growth rate of six- and seven-year-old children.

The effect of in vitro antibacterial properties of bovine milk diets on the natural colonisation of newborn piglets with coliform bacteria

The diets suitable for the hand rearing of piglets in incubators were examined. Diet A was based on cows' milk heated to 56 degrees C and had bacteriostatic and antiadhesive properties against Escherichia coli. Diet B was based on evaporated cows' milk and did not have these properties. The numbers of coliform bacteria naturally colonising the small intestines of newborn piglets fed entirely on these diets for one week did not differ significantly, however both were significantly higher than in control piglets suckled from birth. Faecal counts of coliforms were similar in all three groups. Examination of the bacteriostatic sensitivity of the isolated strains to sows' milk indicated a predominance of milk-sensitive strains colonising the suckled piglets and a predominance of milk-resistant strains in the piglets fed diet B. This diet-dependent colonisation could not be explained by the in vitro bacteriostatic properties of the diets alone.

A putative role for cell-cell epithelial contacts in lactose secretion

Rates of synthesis and secretory release and the maximal requisite intracellular transit time (Tsec) for lactose were measured in vitro for three preparations of lactating guinea pig mammary tissue: tissue slices, mammary epithelial cell (MEC) acini, and mono-dispersed MEC. The Tsec values for tissue slice and acini preparations were similar, lactose required approximately 16 min to pass from its site of synthesis (Golgi) to the extracellular medium. Dispersal of mammary tissue into single cells by collagenase disruption of all cell-cell junctional complexes increased the Tsec value to approximately 25 min but did not alter kinetics of lactose synthesis and secretory release. These data suggest a possible involvement of cell-cell junctional contacts in intracellular transport of lactose.

Intestinal absorption of zinc: a role for a zinc-binding ligand in milk

This study examined the proposal that a low molecular weight, zinc-binding ligand (ZBL) in certain milks is important for zinc absorption in the neonatal period. Ten-day-old rats, in which intestinal ZBL is absent, fed (by stomach intubation) 65Zn-labeled ZBL from rat milk, absorbed significantly more 65Zn than those fed free 65ZnCl2 or bovine milk fractions. ZBL from human milk appeared to have an intermediate effect, possibly due to species specificity. 65Zn was found in the ZBL fraction in intestinal mucosa of 10-day-old rats fed rat or human milk fractions, but not in those fed bovine milk or free 65ZnCl2. In contrast, in 18-day-old rats, which have an endogenous intestinal ZBL, there were no differences in zinc absorption, and any of the labeled milk fractions or free 65Zn caused localization of 65Zn in the ZBL fraction of intestinal mucosa. These results support the hypothesis that the intestinal ZBL plays a role in zinc absorption and that in the neonatal period before its development the milk ZBL is valuable for this function. This mechanism may be important in normal human infants as well as in acrodermatitis enteropathica patients.

The human rumen

The cow is a ruminant, and cow's milk has evolved to promote bacterial growth in the upper small bowel; whereas human milk has evolved to discourage bacterial growth. Examination of the constituents of the two milks shows that their differences can be accounted for in terms of this difference in function. Children who are fed a calf's diet tend to develop a rumen. This may lead to chronic diarrhoea and malnutrition and may be a factor in diarrhoea ascribed to cow's-milk-protein allergy and lactose intolerance.

The lactoperoxidase-thiocyanate-hydrogen peroxide antibacterium system

Lactoperoxidase present in various secretions oxidizes thiocyanate (SCN-) in the presence of H2O2 to an unstable oxidation product--hypothiocyanite (OSCN-), which is bactericidal for enteric pathogens including multiple antibiotic resistant strains of E. coli. The system damages the inner membrane causing leakage and cessation of uptake of nutrient, leading eventually to death of the organisms and lysis. The possible involvement of O2- and 1O2 is discussed.

Relationship between milk yield and mammary gland development in mice

Female mice from four lines exhibiting different nursing ability (as measured by mean 12-day weight of eight offspring within a nursed litter) were used to examine milk yield, body size, feed intake, and cellular development of mammary glands and liver. Three selected lines exceeded the control line in milk yield and mammary gland and liver weights. They had more total deoxyribonucleic acid, ribonucleic acid, and protein contents in both mammary gland and liver tissues than the control. Phenotypic correlations between milk yield and deoxyribonucleic acid contents of mammary glands and liver were .39 and .35, while correlations between milk yield and protein to deoxyribonucleic acid ratio of mammary glands and livers were .04 and .11. Milk yield was correlated closely with body size .57 and with feed intake .55. Milk yield was related more to cell number than to cell size of the mammary glands and liver, and large amounts of milk were produced by heavy dams with substantial feed intake.

The supression of milk fat globule secretion by clochicine: an effect coupled to inhibition of exocytosis

The effects of colchicine on release of milk lipids from mammary tissue were evaluated by biochemical analysis of milk and morphological study of the tissue following intramammary infusions of the alkaloid into lactating goats. Colchicine produces a reversible drop in milk yield. As the flow of milk resumes, 36--48 h after infusion, the fat content of the milk increases, phospholipid per g of total globule lipid falls, mean size of milk fat globules increases and diameters of fat droplets (presecretory milk fat globules) within lactating cells approximately double. These observations are consistent with the conclusion that colchicine suppresses milk fat globule secretion but that globules continue to grow in size wihtin cells during the suppression period. These findings indicate that secretion of milk fat globules and the skim milk phase are coupled.

The leukocyte as a defense mechanism

Within the udder, neutrophil polymorphonuclear (PMN) leukocytes are capable of phagocytosing a wide variety of particles (microorganisms, milk fat globules, casein). Studies of PMN leukocyte function indicate that milk fat globules and casein are perhaps significant deterrents to phagocytosis and destruction of Staphylococcus aureus by PMN leukocytes in milk. These deterrents could be a major factor in establishment of intramammary infections by invading mastitis pathogens. Elimination of fat and casein from milk during clinical or subclinical mastitis may free PMN leukocytes to function properly and may remove infection from the mammary gland. Further observations on PMN leukocyte function indicate that considerable variation exists among cows in the ability of whole milk and skimmed milk to support phagocytosis and in the ability of PMN leukocytes to phagocytose. Variation in this basic defense mechanism could account for the differences that exist in susceptibility to infection by mastitis pathogens.

Differences in subcutaneous fat in breast- and formula-fed infants

During the first 6 weeks of life, 87 breast-fed infants had a significantly greater increase in skinfold thickness than 173 infants fed only with artificial milk formulae. The two groups were similar in respect of racial origin, gestational age, birthweight, and weight gain in the first 6 weeks of life. These findings show that formula-fed infants have a different distribution of body fat from breast-fed infants.

Antiviral activity in milk of possible clinical importance

In human and in cow's milk an antiviral activity has been detected which does not seem to be related to antibodies or other known virus inhibitors. The antiviral activity lay in a relatively heat-stable macromolecule belonging to the non-fatty part of milk.

Mechanisms of secretion: effects of colchicine and vincristine on composition and flow of milk in the goat

Colchicine, the plant alkaloid, produced a dramatic decrease in milk flow when infused into the udder of the goat. The compound (1 to 5 mg) dissolved in 5 ml of water was inserted into one side of the under via the teat canal. Such treatments consistently caused a depression in milk yield from the infused side with maximum at 36 h and substantial reversal by 72 to 96 h. Milks from both the infused and uninfused sides of the udder were essentially normal in composition (fat, protein, and lactose). However, globulins and riboflavin were elevated in milks from the infused side. The plant alkaloid, vincristine, produced effects on milk secretion similar to those of colchicine but at dosages roughly one-tenth the latter. The two substances had no effect on the amount of milk from the uninfused side of the udder. Experiments employing [carbon-14] colchicine revealed that less than 20% of the infused colchicine is secreted in the milk. Both the secretion of fat globules and the emptying of secretory vesicles by the lactating cell are inhibited by colchicine indicating that a portion of the cell population is turned off from secretion. Plant substances such as colchicine and vincristine may at times limit yields of milk, especially in grazing ruminants.

Changes in body weight, milk production, food and water consumptions and vaginal smears in rats during prolonged lactation

Concurrent observations were made in the rat on the changes in the milk production, body and organ weight, food and water consumptions and in the ovarian function in two separate series of experiments in which the period of lactation was prolonged to 60 and 45 days, respectively, by replacing suckling pups by younger ones. In most of the variable examined, marked changes occured between day 20 and 30 of lactation, that is, at the stage correspondong to the end of the normal lactation period. Milk production rate during prolonged lactation expressed by daily gain in weight of litters decreased to 60% of the level before day 20, and was associated with a great reduction of nucleic acid contents of the mammary gland. Definite decreases in weight of the anterior pituitary and the adrenal glands were observed. The food intake remained constant from day 15 of lactation onwards, therefore, the feed efficiency for milk production declined gradually during the period of normal lactatation remaining at a low level thereafter.. After the first recurrence of vaginal estrus which also occured between day 20 and 30, the replacement of litters was followed by the appearance of estrus, whereas replacement before day 15 did not affect the ovarian function. In addtition to these changes, a depressing effect of estrus on the milk production was observed.

Lactational efficiency complex of rats: provisional model for interpretation of energy balance data

In experiments to determine maintenance requirements and partial efficiencies of conversion of diet and body tissue to milk, correlations between independent variables interfered with multiple regression procedures usually used in analyzing nutritional energetic data. Therefore, an alternative of a largely deterministic model of energy transformations in lactating rats was developed. Food intake, initial and final body weights, and diet composition were inputs to the model. These inputs were partitioned among the several metabolic functions of lactating rats within the model, and estimates of milk energy, heat increment of production, energy used for maintenance, and heat increment of maintenance were computed. The model was validated with rats and diets not used in model development. Inferences were: (a) average efficiency of body energy conversion to milk is 83%; (b) average gross and net efficiencies of milk production on balanced rations are 57 and 80%; and, (c) maintenance requirements vary as a function of food intake. A logistic function relating maintenance to food intake was developed based on the postulate that changes in intake of food cause changes in weights of several vital organs changing the maintenance requirement. This postulate explains, in part, changes in maintenance requirements during long food restriction and during gestation and lactation.

Use of 1,3-butanediol for lactation and growth in cattle

These studies have been designed to test whether 1,3-butanediol (BD) alleviates milk fat depression in lactating cows, to observe physiological changes in blood and rumen constituents when BD is fed to cows or growing cattle, and to test the effects of BD on growth rates and feed efficiency in growing cattle. In trials with lactating cows, milk fat percentage and total fat production were higher for cows fed BD than for controls. Feeding BD to either cows or growing cattle had no consistent effect on rumen pH or relative concentrations of rumen volatile fatty acids. 1,3-Butanediol feeding had little effect on blood glucose concentrations. Feeding more than 4% BD in diets sometimes caused increased concentrations of blood ketones. In trials where growing cattle were fed 4% BD, rates of gain and feed efficiency were at least as good as and often better than those of cattle fed the same diets without BD. Body composition was not significantly affected. 1,3-Butanediol can be utilized effectively as an energy source for cattle and causes no obvious problems with 4% in diets.

Postnatal stimulation: the effects on cholinergic enzyme activity in undernourished rats

Rats were malnourished during the first 3 wk of life by feeding their lactating dams a low protein diet. Half of both control-fed and malnourished groups were "handled" daily during the suckling period. After 4 wk of postweaning dietary rehabilitation and individual caging they were killed and brain minus cerebellum taken for choline-acetyltransferase (ChAc) and acetylcholinesterase (AChE) determination on neuronal-rice or glial-rich cell fractions. Early postnatal malnutrition resulted in a decrease in ChAc activity in the neuronal-rich cell fraction of the non-handled rats, but no change in ChAc activity of this cell fraction was observed from rats that had been handled. This finding parallels the prior observation that malnutrition induces behavioral changes that continue after nutritional rehabilitation, but these behavioral abnormalities are minimized or abolished by handling.

[Effect of various factors on the electric conductivity of mixed milk]

The authors evaluated the method of the determination of the electric conductivity of purchased milk for the estimation of the hygienic aspects of milk quality and for mass diagnosis of the inflammatory diseases of dairy cow mammary glands. The variability coefficient of duplicates varied from 1.37 to 3.09%. The study of the dependence of milk conductivity measurement on milk temperature revealed a statistically highly significant positive correlation between the values of these two factors. In the temperature range from 30 degrees C to 35 degrees C the coefficients of correlation ranged from 0.951 to 0.996. Furthermore, interference caused by milk acidity was examined during a five-day incubation of samples at 25 degrees C. A statistically significant difference was observed from the third hour of incubation (P less than 0.05) and a statistically highly significant difference from the fourth hour of incubation (P less than 0.01). The evaluation of the diagnostic value of the method of the measurement of electric conductivity in purchased milk revealed a positive correlation to the content of chloride ions (r = 0.69) and to the number of the cellular elements of milk (r = 0.33).

Periodic omission of dairy cow milkings. II. Effect on the composition and processing properties of herd milk

Forty-five Friesian cows were assigned to one of 3 milking management treatments: (1) cows milked 14 times weekly, (2) cows milked 13 times weekly (Wednesday morning milking omitted) and (3) cows milked 12 times weekly (Tuesday evening and Wednesday morning milkings omitted). The trial continued for 12 months.

Milking omission led to compositional changes in herd milk similar to those described for subclinical mastitis, including increases in pH, chloride level and cell count. Alterations in processing properties consistent with these changes were encountered. Heat stability and curd firmness were affected by extending the milking interval, but the magnitude and direction of the effects varied.

Where only one milking was omitted weekly, herd milk arriving at cheese or powdered-milk factories would not be expected to cause any serious technical difficulties. Omission of 2 consecutive milkings a week would cause processing difficulties where milk was to be condensed or dried, since the maximum heat stability obtained by pH adjustment was reduced.

Residual milk yield as affected by dose and time of injection of oxytocin

A study was made, using Holstein cows, of the relationship between (1) the dose of oxytocin administered; (2) the time between milking and intravenous (i.v.) injection and (3) the time between injection and withdrawal of residual milk. Effectiveness of each dose for removal of residual milk was expressed as the percentage of residual milk in the quarter which was withdrawn by a test milking. The total amount of milk in the quarter was determined by giving a large dose of oxytocin and a second test milking, which then indicated the volume of milk missed by each combination of dose and delay times. It was found that delay before injection had no consistent influence on the effectiveness of the test dose; however, an increased delay after injection required an increase in the test dose for removal of a constant percentage of residual milk. The mean dose required for 75% removal increased from 6·3 mu/kg bodyweight to 57 mu/kg bodyweight as the time from injection to removal of residual milk increased from 5 to 30 min. The doses which produced removal of 75% of the residual milk in at least 50% of the quarters tested were 5, 10 and 40 i.u. for delays between injection and removal of residual milk of 5, 15 and 30 min respectively.

Periodic omission of dairy cow milkings. I. Effect on milk yield and composition and on udder health

Forty-five Friesian cows were assigned to one of 3 milking management treatments: (1) cows milked 14 times weekly, (2) cows milked 13 times weekly (Wednesday morning milking omitted), and (3) cows milked 12 times weekly (Tuesday evening and Wednesday morning milkings omitted). Cows were removed from the trial at the end of their lactations, and newly calved cows were added as they became available. The trial was continued for 12 months.

When one milking was omitted weekly, the total lactational milk yield was reduced by 3·5%, fat yield by 2% and protein yield by 1·5%. These reductions were not statistically significant. When 2 consecutive milkings were omitted, the yield of milk and of its main components was reduced by 14% (P < 0·001). The effects were greatest for highly productive cows in early lactation.

When one or 2 milkings were omitted the milk yield on the following day was nearly 50% greater than the mean daily yield. No increase in the incidence of subclinioal mastitis was observed in either milking omission treatment.

It is concluded that it is practicable to omit one milking each week though it is suggested that the technique should not be used in highly productive herds unless most of the cows are past the sixth week of lactation.

Intracellular concentrations of sodium, potassium and chloride in the lactating mammary gland and their relation to the secretory mechanism

1. The intracellular (I.C.) concentrations of Na, K and Cl in mammary cells from lactating guinea-pigs have been calculated from the analysis of fresh tissue and the measurement of the extracellular (E.C.) space with [(14)C]sucrose and the milk content with [(14)C]lactose.2. Assuming that alveolar milk has the same concentration as teat milk, the intracellular concentrations were calculated to be K 115, Na 42 and Cl 66 m-equiv. l(-1) intracellular water.3. Intracellular concentrations were also calculated in slices incubated in Krebs-bicarbonate medium plus glucose. There was a large increase in the sucrose (E.C.) space and a rise in total tissue [Na] and [Cl]. On the assumption that the medium had equilibrated with the milk space as well as the E.C. space, the calculated I.C. concentrations of Na (43 m-equiv. l(-1)), and Cl (62) were very similar while [K] was somewhat higher (143 m-equiv. l(-1)I.C. water).4. The calculated I.C. concentrations of all three ions are all higher than in milk but the ratios between them are almost identical.5. Similar figures for the I.C. concentrations of Na, K and Cl have been obtained in the goat, cow and sheep mammary tissue incubated in vitro.6. Moderate changes in the concentrations of Na, K and Cl in the external medium had no effect on cell composition but during incubation without ions [(14)C]sucrose became distributed throughout the total tissue water indicating that sucrose had entered the I.C. compartment.7. Acetazolamide (10(-2)M), aldosterone (1.4 x 10(-6)M) and, in some experiments, lack of glucose lowered I.C. [Cl(-)], but oxytocin, vasopressin and low doses of insulin had no effect.8. The data are difficult to reconcile with the hypothesis of Zaks, Natochin, Sokolova, Tanasiichuk & Tverskoi (1965) that freshly secreted milk has the ionic composition of plasma.9. Comparison of I.C. ion concentrations and the membrane potential between the cells and milk suggests that Na(+) and K(+) are passively distributed across the apical membrane but that Cl(-) must be actively held in the cells. Across the basal membrane the data are consistent with the presence of a Na(+) pump and with Kinura's (1969) detection of a Na:K ATPase on the basal and lateral membranes. In addition another inward-facing Cl(-) pump may exist at this site.

The permeability of mammary ducts

1. The permeability of the teat mucosa of the goat has been studied in vitro and, as an isolated teat pouch, in vivo. In vivo the mucosa was found to be impermeable to radioactive Na, K, Cl and Rb isotopes and to labelled lactose, but permeable to (3)HOH, and to a lesser extent, urea.2. The permeability of the intramammary ducts has been assessed by comparison of the rates of passage from the blood of ions and urea relative to (3)HOH into various fractions of milk in different parts of the gland.3. Negligible quantities of ions were detected in the milk present in large ducts after an I.V. infusion or during a close arterial infusion to keep the venous blood concentrations constant. However, after approximately 25 min, milk in the alveoli had fully equilibrated with (3)HOH, and (24)Na(+) and was almost fully equilibrated with urea but not with (42)K(+) and (36)Cl(-).4. The quantity of milk in a fraction of milk was directly related to the amount of (3)HOH present in that fraction but not to the amounts of the other indicators (urea, labelled Na, K, Rb and Cl). Comparison of the concentration of these substances with (3)HOH in different milk fractions indicates that the mammary ducts are probably impermeable to ions and only slightly permeable to urea.5. The injection of [(14)C]lactose into the teat showed that after 10 and 20 min, 7 and 14% respectively of the radioactivity had reached the residual (alveolar) milk. Thus diffusion within the milk in the ducts could account for the small quantities of labelled ions found in milk within the ducts following intravascular injection.6. It is concluded that the large and medium-sized ducts in the mammary gland are impermeable to lactose and to the monovalent ions studied.7. In non-lactating animals, the ducts are more permeable to Na(+) and Cl(-) than in the lactating animals.8. The relative rates of passage of ions into residual (alveolar) milk was Na > Cl > K.

A study of the antihormonal activity of an antiserum to ovine prolactin using the local lactogenic response in the rabbit

A rabbit antiserum to a purified preparation of ovine prolactin was prepared. The capacity of the antiserum to counter the biological effect of the preparation of ovine prolactin was determined. When injected intraductally before the injection of prolactin into the same duct the antiserum inhibited the lactogenic effect of prolactin on the rabbit mammary gland. The weight, nitrogen content and reducing sugar content of the mammary glands were used as criteria to judge the effect of the antiserum. The results of specificity tests on the antiserum, using the techniques of double diffusion and immunoelectrophoresis, are also reported.