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PubMed1994

Once daily milking of dairy cows: relationship between yield loss and cisternal milk storage.

The proportions of milk stored in the gland cistern (cisternal) and within secretory alveolar tissue (alveolar) were determined for a group of ten cows in mid lactation, yielding approximately 20 kg milk/d. As a proportion of total milk, cisternal milk, measured at 8 h after milking, ranged from 0.09 to 0.53. Milking frequency was then reduced from twice daily to once daily on two occasions, first for 1 week and then, 2 weeks later, for 2 weeks. Milk yield was reduced during once daily milking in all cows, by an average of 22.8% during the first week (P < 0.001). The amount of decrease varied among cows in a way that was unrelated to pretreatment yield, but the immediate decrease was significantly and inversely correlated with cisternal milk proportion (r = 0.81, P < 0.01). When milking reverted to twice daily, yield recovered to a value not significantly different from pretreatment, and the degree of recovery was inversely related to cisternal milk proportion (r = 0.74, P < 0.01). With the exception of one cow, yield decreases correlated well between the two periods of once daily milking. When treatment weeks were disregarded, lactation persistency (the rate of decline in yield with time) was unaffected by once daily milking. The results show that the ability of individual cows to tolerate once daily milking is related to their cisternal storage characteristics; yield is reduced less in cows that store a greater proportion of their total milk production within the cistern.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Collection of fore and hind milk from the sow and the changes in milk composition during suckling.

A new sampling method for the collection of fore and hind milk from the sow has been developed which resembles normal milk removal by the piglet, yet overcomes the difficulties of collecting milk that is available for only a short time (10-20 s) at each let-down. Samples of hind milk were collected immediately after the completion of a successful sucking, while the fore milk was collected at the beginning of the next natural let-down. Modification of existing assays for fat, protein and lactose was required to provide rapid analysis of the small volumes (less than 0.5 ml) of milk collected using this procedure, and these methods were validated by comparison with reference methods. Total solids and the concentration of fat in whole milk, and protein and lactose in skim milk, were measured in fore and hind milk collected from 4, 20, 12 and 12 sows respectively, 6-11 d post partum. For fore milk, the results (mean +/- SD (n)) were: total solids, 199.9 +/- 9.9 g/l (8); fat, 96.7 +/- 13.9 g/l (41), protein, 47.7 +/- 4.5 g/l (27) and lactose, 58.3 +/- 4.0 g/l (27). In hind milk, there was a significant increase in the concentration of fat (15.3 g/l, P less than 0.001, n = 41) which was reflected by a significant increase in total solids (14.7 g/l, P less than 0.001, n = 8) and calculated energy (511 kJ/l, P less than 0.001, n = 27), but there was no significant difference in the concentration of either protein or lactose. This increase in milk fat during milk let-down is in contrast to the results of most previous studies in the sow and is discussed in terms of the possible mechanisms that may cause the concentration of fat to increase as milk is removed from the mammary gland.

Animals↗
PubMed1992

Bioavailability in man of iron in human milk and cow's milk in relation to their calcium contents.

Iron absorption from human milk and cow's milk was compared in the same subjects using two radio-iron tracers and extrinsic labeling of the iron. Previously observed higher iron absorption from human milk was confirmed as 19.5 +/- 17.3% (mean +/- SD) in cow's milk versus 48.0 +/- 25.5% in human milk; mean individual absorption ratio was 0.39 +/- 0.18 (p less than 0.0001). Cow's milk has a several times higher content of calcium, recently established to be a potent inhibitor of iron absorption. Adding calcium chloride to human milk in amounts to equate the calcium content of cow's milk significantly reduced iron absorption [39.1 +/- 17.8% (mean +/- SD) versus 21.3 +/- 10.6%]; mean individual absorption ratio with or without added calcium was 0.58 +/- 0.12 (mean +/- SD) (p less than 0.0001). Differences in calcium content could explain at least 70% of the difference in iron bioavailability between milks. It is suggested that the remaining 30% difference may mainly be an artifact related to inhomogeneous radioiron-labeling of milk iron compounds, especially in human milk, and that the main difference in true iron absorption between human and cow's milk is related to their different calcium contents. The rather high fractional iron absorption from human milk can be explained by its low iron content. There is nothing to indicate that human milk contains any enhancer of iron absorption. The marked inhibiting effect of calcium on iron absorption should be considered in the design of infant formulas to achieve an optimal balance in the contents of calcium and iron.

Adult↗
PubMed1994

Short-term oxytocin treatment increases bovine milk yield by enhancing milk removal without any direct action on mammary metabolism.

The milk yield-enhancing effect of oxytocin administered either before or after milking was examined using a within-animal model. Eight cows in mid-lactation were changed from normal twice daily milking to a split-milking design, whereby half of the udder was milked at 0500 and 1500 h (control half; normal milking times), and the other half at 0800 and 1800 h (test half). This continued for 3 weeks. During the second week, oxytocin was administered as an i.m. injection immediately before the 0800 and 1800 h milkings. The test half was thus milked immediately after oxytocin administration, whilst the control half was milked 3 h before oxytocin. Milk yield decreased slightly on the adoption of split-milking. The decrease did not differ between udder halves and was not, therefore, due to inadequate milk-ejection in the test half compared with the control. During the week of oxytocin treatment, the yield decreased further in the control half but increased in the test half; consequently, the yield from the test half was significantly greater than that from the control half (P < 0.05). The ratio of change in the test half relative to that in the control half was 1.12, significantly different from unity (P = 0.002). Analysis of variance demonstrated a significant (P < 0.001) interaction between udder half and oxytocin treatment, confirming that the effect of oxytocin was restricted to the test half, treated immediately before milking. This supports the established view that oxytocin acts by enhancing the milk-ejection reflex, and refutes a recent claim that the hormone has a direct stimulatory action on mammary metabolism.

Analysis of Variance↗
PubMed2002

Field validation of a milk-line sampling device for monitoring milk component data.

The objective of this study was to investigate the ability of a milk-line sampling device to obtain a representative sample under field conditions by comparing the milk component composition between milk-line and bulk-tank samples, for milk harvested from the same group of cows at the same milking. A total of 42 paired milk-line and bulk-tank samples were collected at separate milking events from 21 different dairy herds. Samples were analyzed for milk fat (%), true protein (%), and milk urea nitrogen (mg/dl). Concordance correlation coefficients showed a very high level of agreement between the two sample types, with values ranging between 0.82 and 0.95 for the components measured. ANOVA showed that milk component data derived from milk-line samples were neither statistically nor numerically different from milk component data derived from bulk-tank samples. The strategy of monitoring milk component data through milk line sampling should provide dairy producers with inexpensive, timely, and accurate information that will help to improve ongoing nutritional monitoring programs for individual groups of cows within the dairy herd.

Animal Nutritional Physiological Phenomena↗
PubMed2002

The yield and composition of milk in Sarda, Awassi, and Merino sheep milked unilaterally at different frequencies.

Sarda (n = 8), Awassi (n = 8), and Merino (n = 8) ewes were subjected unilaterally to once-daily milking (ODM) or twice daily milking (TDM) to test the hypothesis that the two breeds highly selected for milk production (Sarda and Awassi) would not respond as much to a change in the frequency of milking as the Merino, a wool sheep that has not been selected for dairy production. Milk composition and somatic cell count (SCC) were also assessed to determine if the changes in milking frequency affected milk quality. Milk yield was 24% and 18% lower in ODM udder halves than TDM udder halves in Sarda and Awassi breeds, respectively. The yield loss due to ODM was similar to that observed in Merino ewes (23%) and did not support our hypothesis. Fat content did not differ significantly in any breeds between ODM and TDM udder halves. Protein content was higher in the milk of ODM than TDM udder halves in Sarda and Merino ewes. The SCC was influenced by milking treatment only in the Sarda ewes, with high values observed in the milk of ODM udder halves. The same trend was observed in the Awassi and Merino breeds, but the differences were not significant. The effects on milk yield, composition, and SCC caused by ODM were completely reversed when TDM was resumed. This suggests that in sheep flocks the milk yield losses due to short-time suppression of one daily milking, for example, on festive days, are low and temporary.

Animals↗
PubMed1998

The effect of whey protein concentrate or dried skim milk in milk replacer on calf performance and blood metabolites.

Whey protein concentrate and dried skim milk were each evaluated as the major protein source in milk replacer using four treatments (100% skim milk, 67% skim milk and 33% whey protein concentrate, 33% skim milk and 67% whey protein concentrate, and 100% whey protein concentrate). In the first trial, 64 calves were fed only milk replacer from birth to 6 wk of age. In the second trial, 61 calves were fed milk replacer and were allowed ad libitum intake of starter from birth to 6 wk of age. Calves were fed milk replacer at 10% of birth weight for the first 2 wk and at 12% of birth weight thereafter. In trial 1, average daily gains and feed efficiencies were significantly improved for calves that consumed the milk replacers containing 67 and 100% whey protein concentrate over those for calves that were fed the milk replacer containing 100% skim milk. No difference in growth or feed efficiency caused by treatment was detected in trial 2. Average daily gain in trial 2 was correlated with total starter intake. In trial 1, plasma glucose concentrations were correlated with growth rates and were highest for calves fed the milk replacer containing 67% whey protein concentrate. No differences were found for fecal scores or days scoured between trials. When only milk replacer was fed, higher proportions of whey protein concentrate improved calf performance, but, when starter was also provided, no effect of milk replacer was found.

Animal Feed↗
PubMed1992

Anaphylaxis in a milk-allergic child after ingestion of milk-contaminated kosher-pareve-labeled "dairy-free" dessert.

Milk-allergic persons often rely on kosher labeling to select dairy-free foods. A 2-year-old boy experienced multiple generalized reactions after ingestion of milk or milk products; his serum contained elevated levels of milk-specific IgE antibodies, and his milk skin test was strongly positive. An identical reaction occurred after ingestion of "pareve"-labeled raspberry sorbet. Using an inhibition immunoassay with pooled sera from two milk-sensitive persons as the source of IgE antibodies, we found the milk allergen level in sorbet provided by the family to be 11% of the level found in non-fat dry milk. The milk allergen level in three independently purchased containers of sorbet ranged from 2% to undetectable. The presence of milk in three of four of the sorbets was confirmed by immunoblotting studies, by quantitation of milk proteins by polyacrylamide gel electrophoresis, and by quantitation of lactose by gas chromatography. Subsequently, it was discovered that milk was incorporated into the sorbet when equipment used to package ice cream had been used to package the sorbet. Although kosher labeling may provide assurance to milk-sensitive persons that a particular food does or does not contain milk, such labeling is no guarantee that this is indeed the case.

Anaphylaxis↗
PubMed1991

[Copper, iron and zinc content of preterm and term human milk and cow's milk].

Sixty-eight samples of preterm human milk and 39 samples of term human milk were obtained during 4 weeks postpartum from 7 mothers delivering prematurely and 9 mothers giving birth at term. Eleven cow's milk samples were obtained at random from 11 healthy cows. Samples were measured by flame method using an atomic absorption spectrophotometer (Type WYX-402). The three trace elements content of PT and FT milks decreased significantly with duration of lactation, and the content of each mineral was higher during the first week than that measured during the fourth week. PT and FT milk did not differ significantly in the content of the three elements during the first month of lactation. Copper content of PT milk at each week, iron content of PT milk at the first week and zinc content of PT milk during the first two weeks of lactation are higher than those of cow's milk respectively. The intake of copper, iron and zinc of the preterm infant fed his own mother's milk or cow's milk was calculated. Comparison of the intake level of copper and zinc of breastfed and cow's milk-fed preterm infant with the recommended intake level of the two minerals was made. The results show PT milk is superior to cow's milk for copper, iron and zinc; may be helpful for promoting breast feeding and feeding the preterm infant with supplemental trace elements.

Animals↗
PubMed1993

Small intestinal mucosa IgE plasma cells and specific anti-cow milk IgE in children with cow milk protein intolerance.

In a prospective study we looked for the presence of both IgE plasma cells in small bowel mucosa and specific serum IgE antibodies to cow milk in children suspected of cow milk protein intolerance. Thirty-one children with complaints possibly due to cow milk intolerance were submitted to two consecutive cow milk elimination/challenge tests. The diagnosis of cow milk protein intolerance was confirmed in 16 of our 31 patients on the basis of two positive elimination/challenge tests. IgE plasma cells were found in nine of 16 patients with proven cow milk protein intolerance and in only one of the 15 patients without cow milk protein intolerance (p < .01). The RAST for cow milk was positive in six of 16 infants with cow milk protein intolerance and in two of the 15 other infants. Serum IgE level was of no value for the diagnosis of cow milk protein intolerance. Neither of these diagnostic procedures was sensitive enough to be used as a screening test for cow milk protein intolerance. Furthermore, the relationship between specific IgE antibodies for cow milk and the presence of mucosal IgE plasma cells was poor: five of nine infants with cow milk protein intolerance and the presence of mucosal IgE plasma cells had negative RASTs for cow milk.

Antibodies, Anti-Idiotypic↗
PubMed1990

Excretion of high concentrations of cimetidine and ranitidine into rat milk and their effects on milk composition and mammary gland nucleic acid content.

The excretion of cimetidine and ranitidine into rat milk following single or multiple oral doses and the subsequent effects on their suckling pups and on milk composition and milk synthesis were investigated. Following a single dose of [3H]cimetidine, peak milk cimetidine concentrations were maintained from 1 until 4 hr, while plasma concentrations peaked at 10% of the milk level at 30 min and then declined. Multiple doses of cimetidine (18 or 180 mg/kg/day) on Days 13-16 of lactation led to milk cimetidine concentrations of 17 and 113 micrograms/ml. The milk/plasma ratios far exceeded the theoretical milk/plasma ratio of 2.0. Ranitidine concentrations in rat milk following ranitidine treatment (4.5 or 45 mg/kg/day) were also greater (6.8-15 times) than in plasma, but only slightly greater than the predicted ratio of 5.0. There were no changes in liver weight or in hepatic aminopyrine N-demethylase activity in the cimetidine- or ranitidine-treated dams or their pups. Cimetidine treatment had no effect on milk lipid, solid, or protein content, but at 180 mg/kg/day, caused a significant increase in milk lactose. The RNA/DNA ratio in the mammary gland was significantly increased by cimetidine, suggesting increased milk synthesis. Ranitidine had no effect on milk composition or on mammary gland RNA, DNA, or RNA/DNA. Therefore, high concentrations of cimetidine and ranitidine were excreted into rat milk, but no deleterious effects on the suckling pups, or the composition of the milk, or on the milk synthetic activity were observed.

Aminopyrine N-Demethylase↗
PubMed1992

Milk yield responses to sequential treatments with recombinant bovine somatotropin and frequent milking in lactating goats.

Lactating goats routinely milked twice daily were used. Starting at peak lactation, two groups of five goats were milked three times daily unilaterally (right gland) for 6 weeks, then one group received recombinant bovine somatotrophin (BST) by daily injection for 6 weeks, and finally both groups were returned to unilateral thrice-daily milking (left gland) for 6 weeks. Thrice-daily milking increased milk yield significantly by 10.4%. As thrice-daily milking finished and BST treatment began there was a small (2.7%) but significant increase in whole-udder milk yield in the treated goats and a decline in the control goats; throughout the BST treatment period treated goats produced 14.3% more milk than controls. The effect of BST was the same in glands previously milked thrice daily as in those previously milked twice daily. Milk yield declined as BST treatment finished, but this decline was less in the glands that then began thrice-daily milking. The effect of milking frequency was similar in this period to that obtained earlier in the experiment, and was not different between goats that had previously received BST and those that had not. The results are discussed in relation to the proposed modes of action of BST and frequent milking, and possible interactions between the two.

Analysis of Variance↗
PubMed1979

Bacteriostasis of Escherichia coli by milk. III. The activity and stability of early, transitional and mature human milk collected locally.

Milk from 150 local mothers has been assayed for bacteriostatic activity for milk-sensitive and milk-resistant indicator strains of Escherichia coli. Activity is greatest in colostrum which is active directly against all strains of E. coli. One week after delivery of the baby, milk is active against the milk-sensitive strain and becomes active against the milk-resistant strain in the presence of physiological amounts of bicarbonate and iron-binding protein. This activity decreases within 2--4 days on keeping milk unheated at 4 degrees C but is preserved for at least 4 months and often up to 2 years in milk heated to 56 degrees C then stored at 4 degrees C or in milk frozen, unheated, at -28 degrees C provided it is not repeatedly thawed and frozen. Later lactation milks are usually indistinguishable in activity from 1-week post-partum milk but may be less stable on storage particularly if frozen. Lyophyilization in vacuo preserves activity of early-lactation milk for at least 6 months. Heating milk to above 65 degrees C causes a progressive loss of activity which can be partially restored by adding bicarbonate and iron-binding protein. Iron abolishes the activity of milk and reduces that of colostrum.

Bicarbonates↗
PubMed2005

Effect of human milk fortifiers on bacterial growth in human milk.

BACKGROUND: As a component in human milk fortifiers (HMF), iron may equilibrate with human milk for as long as 24 hours, bind important bacteriostatic proteins, and potentially affect the host defense properties of human milk. OBJECTIVE: We compared bacterial growth in human milk prepared with each of two HMF differing in their content of iron. STUDY DESIGN: Samples of human milk obtained from mothers of premature infants were divided and mixed with one of two HMF and maintained at refrigerator temperature. Refrigerated milk samples were removed at 0, 24, and 72 hours for determination of total bacterial colony counts (TBCC). RESULTS: TBCC did not differ between groups but declined from 0 to 72 hours, p<0.001. CONCLUSION: These data suggest that differences in iron content, or other nutrients in HMF, do not affect bacterial growth in human milk. Storage of fortified human milk at refrigerator temperature for 72 hours results in decreased bacterial growth. As a component in human milk fortifiers (HMF), iron may equilibrate with human milk for as long as 24 hours, bind important bacteriostatic proteins, and potentially affect the host defense properties of human milk. We compared bacterial growth in human milk prepared with each of two HMF differing in their content of iron. Samples of human milk obtained from mothers of premature infants were divided and mixed with one of two HMF and maintained at refrigerator temperature. Refrigerated milk samples were removed at 0, 24, and 72 hours for determination of total bacterial colony counts (TBCC).

Bacteria↗
PubMed2026

CanDo (Canadian Donor Milk) randomised controlled trial: pasteurised human donor milk supplementation in the well-baby unit - protocol.

INTRODUCTION: Mother's milk is the gold standard for feeding newborns. Despite lactation support while in hospital, supplementation rates remain high in Canadian well-baby units at 35-50%. When supplementation is needed, the choice between formula milk and pasteurised human donor milk (donor milk) remains uncertain with a lack of clinical trials to inform this practice. This study aims to compare the effect of supplementing mother's milk with donor milk versus formula in infants at higher risk for supplementation (infants of diabetic mothers, infants born small for gestational age or with a birth weight less than 2.5&#x2009;kg and late preterm infants born between 350/7 and 366/7 weeks gestation). METHODS AND ANALYSIS: This is an ongoing, open-label, single-centre, randomised controlled trial conducted at Mount Sinai Hospital, Toronto, Canada. A total of 112 infants (56 per group) will be randomised to receive donor milk or infant formula as a supplement to mother's milk during their initial hospital stay, when supplementation is deemed necessary by the family and/or healthcare team. The primary outcome is exclusive human milk feeding at 4 months of age. Secondary outcomes include any or exclusive human milk feeding at 1, 2 and 3 months; infant growth and health indicators and breastfeeding self-efficacy. Exploratory outcomes encompass infant temperament; parental mental health (assessed using the State-Trait Anxiety Inventory and Edinburgh Postnatal Depression Scale); milk cortisol concentrations; and informal milk sharing comparing donor milk and formula supplementation. Follow-up includes monthly telephone assessments and a virtual or in-person visit at 4 months post partum. Data will be analysed using intention-to-treat principles. ETHICS AND DISSEMINATION: The CanDo trial has received ethics approval from the Mount Sinai Hospital Research Ethics Board and the University of Toronto. Results will be disseminated through peer-reviewed journals, conference presentations and stakeholder engagement with hospital and public health decision-makers. Findings will address a critical evidence gap regarding the use of donor milk supplementation in well-baby units and may inform future clinical practice and policy in newborn feeding. TRIAL REGISTRATION NUMBER: NCT06315127.

Humans↗
PubMed1992

Milking frequency alters the milk yield and mammary blood flow response to intra-mammary infusion of insulin-like growth factor-I in the goat.

The milk yield and mammary blood flow responses to close-arterial, intra-mammary infusion of IGF-I were investigated in five Saanen goats milked frequently or normally the day before. Animals were infused for 6 h with recombinant human IGF-I (1.3 nmol/min) and milked hourly following i.v. injection of oxytocin beginning 2 h before infusion and then every 2 h. On one occasion animals were milked five times (after i.v. injection of oxytocin) on the day before infusion and on the other they were milked twice, without oxytocin. The ratio of milk yield from the infused to that from non-infused gland increased by 17 +/- 4% (mean +/- S.E.M.) in goats milked twice the day before infusion and by 6 +/- 2% when the infusion was preceded by frequent milking. Maximal responses were obtained 4 h after the start of the infusion and differed significantly (P < 0.05), according to pretreatment milking. Blood flow through the infused gland rose in parallel to the milk yield response. At 5 h, when maximal levels were achieved, blood flow was 182 +/- 23% of the pre-infusion flow rate following twice-daily milking and 139 +/- 3% of the pre-infusion flow rate following more frequent milk removal. Thus, more frequent milk removal on the day before close-arterial infusion of IGF-I attenuated both the milk yield and mammary blood-flow response to the infusion of IGF-I.

Animals↗
PubMed1990

Techniques for estimation of milk yield in beef cows and relationships of milk yield to calf weight gain and postpartum reproduction.

Milk production is a primary factor controlling weaning weight of beef calves. The purpose of this experiment was to develop a practical and reliable on-farm method of estimating milk production and to relate estimates of milk production and milk composition to preweaning weight gain of calves. A second objective was to relate milk production to postpartum ovarian activity. Milk production of spring- and fall-calving grade Angus cows was estimated by machine milking (MM; average of 66, 123 and 189 d postpartum) and weigh-suckle-weigh (WSW; average of 50, 95, 136 and 179 d postpartum) techniques following overnight calf removal. Cows and calves were weighed monthly and the postpartum interval to first ovulation following calving was determined. The repeatability of the estimated milk production by MM (.97) was higher (P less than .01) than by WSW (.35). The correlation of average WSW and average MM estimates of milk production with preweaning calf gain were high and similar (greater than .75). Inclusion of milk composition did not improve the multiple correlation of MM-estimated milk production and calf gain. Neither milk production in early lactation (-.06) nor prebreeding weight change (-.07) was correlated with postpartum interval to ovulation. Machine milking was a repeatable method of estimating milk production of beef cows and can be used to evaluate effects of management variables on lactation of beef cows.

Animals↗
PubMed1992

Relationship between milk expected progeny differences of polled Hereford sires and actual milk production of their crossbred daughters.

One hundred sixteen spring-calving Polled Hereford x Angus cows were milked using milking machines after receiving 20 IU of oxytocin. Sires of the cows had been divergently selected on yearling weight (YW) and total maternal (MAT) EPD to form four groups: high YW, high MAT EPD; high YW, low MAT EPD; low YW, high MAT EPD; and low YW, low MAT EPD. Average milk production after 12-h calf separation was 3.7 +/- 1.3 kg. Actual milk production of cows was regressed on their sires' milk EPD, where the milk EPD estimates the additive maternal genetic contribution of a sire to the weaning weight of his daughters' calves. The regression of actual 12-h milk production on sire milk EPD was .038 +/- .014 kg/kg, and the correlation was .26 (P less than .006), close to its expected value, based on the accuracy of the prediction, heritability of the trait, and the relationship between sire and daughter. Extension of results of a single milking to an entire lactation is difficult, but over the range of sire milk EPD sampled (-10 to 16 kg), the range in daughters' milk production predicted from the regression analysis was 27% of the mean actual milk production, corresponding to an increase of about 1% more milk per kilogram of milk EPD.

Animals↗