Incomplete Milking Research Articles

Relationship between udder morphology traits, alveolar and cisternal milk compartments and machine milking performances of dairy camels (Camelus dromedarius)

A total of 22 dairy dromedary camels under intensive conditions in late lactation (275±24 days) were used to study the relationship between external and internal udder morphology and machine milking performances. Measurements of udder and teat morphology were obtained immediately before milking and in duplicate. Individual milk yield, lag time and total milking time were recorded during milking, and milk samples were collected and analyzed for milk composition thereafter. Cisternal and alveolar milk volumes and composition were evaluated at 9 h milking interval. Results revealed that dairy camels had well developed udders and milk veins, with medium sized teats. On average, milk yield as well as milk fat and protein contents were 4.80±0.50 L d-1, 2.61±0.16% and 3.08±0.05%, respectively. The low fat values observed indicated incomplete milk letdown during machine milking. Lag time, and total milking time were 3.0±0.3, and 120.0±8.9s, on average, respectively. Positive correlations (p<0.05) were observed between milk yield and udder depth (r=0.37), distance between teats (r=0.57) and milk vein diameter (r=0.28), while a negative correlation was found with udder height (r=-0.25, p<0.05). Cisternal milk accounted for 11% of the total udder milk. Positive correlations were observed between total milk yield and volume of alveolar milk (r=0.98; p<0.001) as well as with volume of cisternal milk (r=0.63, p<0.05). Despite the low udder milk storage capacity observed in dairy camels, our study concluded that the evaluated dromedary sample had adequate udder morphology for machine milking. Finally, positive relationships were detected between milk yield and udder morphology traits of dairy camels.

The effect of incomplete milking or nursing on milk production, blood metabolites, and immune functions of dairy cows

During the transition from pregnancy to lactation, the sudden increase in nutrient demand for milk production causes metabolic perturbations and is associated with immunosuppression and a high incidence of metabolic and infectious diseases in high-yielding cows. In this study, we examined whether limiting milk harvest postpartum while maintaining milking stimulus could improve the metabolic status of cows without reducing overall milk production. Forty-seven Holstein cows were milked completely twice a day from calving (control); milked incompletely (about one-third of expected milk production was collected) twice a day until d 5 after calving (incomplete); or left to nurse their calf until d 5 and milked once a day from d 3 to d 5 (nursing). All cows were milked twice a day from d 6 to the end of the experiment (d 61). During the treatment period (d 1 to 5), milk production averaged 27.3 and 9.7kg/d for the control and incomplete treatments, respectively. We observed no residual effect of treatment on milk production, which averaged 47.8, 45.7, and 46.4 kg/d for the control, incomplete, and nursing treatments, respectively, between wk 2 and 9. The dry matter intake of the cows was similar during and after treatment. From wk 2 to 9, milk protein and lactose percentage were not affected by treatments, but milk fat tended to be higher in control cows than in cows milked partially (incomplete + nursing). Blood concentrations of glucose and phosphorus were lower and concentrations of nonesterified fatty acids and β-hydroxybutyrate were higher in control cows than in partially milked cows during the treatment period. The positive effects on glucose and β-hydroxybutyrate remained significant up to d 28. Peripheral blood mononuclear cell (PBMC) proliferation and secretion of IL-4 were depressed during the postpartum period, and proliferation tended to be greater for cells incubated in serum from cows in the incomplete treatment on d 5 but lower on d 61. We observed no effect of treatments on polymorphonuclear neutrophilic leukocyte chemotaxis or phagocytosis. Proliferation and IL-4 secretion of PBMC were negatively correlated with concentration of serum nonesterified fatty acids. Reducing milk harvest postpartum while maintaining milking stimuli reduced metabolic stress without compromising productivity of high-yielding dairy cows.

Endocrine responses and milk emission characteristics in high yielding Alpine dairy goats under once daily milking management

This study was done to verify if the lack of increase of milk fat content observed in Alpine dairy goats under once daily milking (ODM) compared to twice daily milking (TDM), results from disturbances of animals and/or milk ejection reflex. In this respect, we determined the milk yield and composition in the same 12 multiparous Alpine dairy goats when they were managed first under TDM (period 1: P1) and then under ODM (period 2: P2). Furthermore, oxytocin (OT) and cortisol (CORT) releases and milk emission kinetic of these goats were measured at morning milking 2 and 4 times in P1 and P2, respectively. ODM compared to TDM, caused 18 and 23% reductions, respectively in daily milk yield and milk fat content without milk protein content modification. Although baseline concentration of blood OT was lower under ODM than TDM management (7.0 pg/mL vs 17.8 ± 2.0 pg/mL, respectively), ODM did not modify the total amount of OT released during milking (15,484 pg/mL/32 min vs 18,996 ± 2865.3 pg/mL/32 min, respectively), the peak concentration of OT (57.2 pg/mL vs 73.6 ± 10.5 pg/mL, respectively) or the time to reach it (3.0 min vs 2.0 ± 0.5 min, respectively) by comparison to TDM. ODM compared to TDM, never modified the baseline concentrations of CORT (6.1 ng/mL vs 7.1 ± 1.1 ng/mL, respectively), the total amount of CORT released (11,727 ng/mL/32 min vs 10,073 ± 1522.2 ng/mL/32 min, respectively), the peak concentrations of CORT (16.1 ng/mL vs 15.1 ± 2.1 ng/mL, respectively) and the time to reach it (13.1 min vs 11.0 ± 1.5 min). During ODM, milk flow latency was reduced (−61%) while the mean flow rate was increased (+28%) by comparison to TDM. ODM compared to TDM management, did not modify the maximum flow rate (1.6 L/min vs 1.6 ± 0.2 L/min, respectively) or the time to reach this maximum (103.0 s vs 95.0 ± 10.0 s, respectively). The total milking duration at morning milking was not different (250.0 s vs 221.0 ± 22.0 s, respectively) although the morning milk yield was significantly higher under ODM management (2.63 kg/d vs 1.87 ± 0.1 kg/d, respectively). This results show that milk emission is improved under ODM management in Alpine goats without inhibition or disturbance of neuro-hypophyseal OT release pattern and lack of activation of the hypothalamic–pituitary–adrenal axis and plasma cortisol increase, disproving our initial hypotheses of a disturbance of animals and/or incomplete milk ejection to explain the low fat content of milk under ODM in this breed.

Incomplete milking has no detectable effect on somatic cell count but increased cell count appears to increase strip yield

Milking regimes that can greatly shorten the milking duration of slow-milking cows to improve labour productivity can also result in less complete milking for some cows. There is also a common belief and limited experimental evidence that incomplete milking of subclinically infected cows can cause increased somatic cell count (SCC). To test for this possible detrimental effect of shorter milking regimes, ‘complete’ milking [to automatic cluster remover (ACR) setting of 300 mL/min] and ‘incomplete’ milking (to an ACR setting of 800 mL/min) were applied sequentially to 45 cows over 7 weeks. Incomplete milking resulted in an average of 0.3 L of extra milk being left in the udders, but there was no significant increase in quarter SCC in either infected or uninfected udder quarters. Change in SCC was not related to change in strip yield induced by incomplete milking treatment. In contrast, cow strip yield was positively related to SCC, or the number of infected quarters/cow, regardless of the applied ACR treatment. These apparently contradictory findings are reconciled by noting that infection causes both high strip yields (via uneven yielding quarters) and high SCC. It is concluded that, contrary to popular belief, high SCC, as an indicator of infection, causes high strip yield and that increasing strip yield does not increase cell count.

Effect of different milking routines on milking-related release of the hormones oxytocin, prolactin and cortisol, and on milk yield and milking performance in Murrah buffaloes

Milking-related release of oxytocin, prolactin, and cortisol was studied following three premilking treatments. Six Murrah buffaloes were treated with direct application of milking cluster (O), a 1-min pre-stimulation (M), and combined feeding and pre-stimulation (MF). Machine milk yield, stripping yield and milk composition were recorded. Milk ejection occurred significantly earlier with MF than M and O (P<0.05; 2.50, 5.10 and 6.33 min, respectively). In all treatments, milk ejection occurred with small increases >3-5 ng/l in oxytocin concentration. Increase in oxytocin concentration over a threshold level and milk ejection occurred simultaneously and were closely correlated (r=0.83, P<0.05). There was a positive correlation between total time oxytocin concentration remained elevated over threshold levels and machine yield (r=0.86, P<0.05). For treatment O, milk ejection was inhibited during machine milking, while a marked increase in oxytocin occurred during hand stripping (6 and 16 ng/l, respectively). For treatment M, mean oxytocin concentrations remained unchanged during prestimulation but increased during subsequent machine milking and hand stripping (6.38, 18.06 and 12.36 ng/l, respectively). For treatment MF, although there was a 3.6-fold increase during pre-stimulation, oxytocin increased by 10-fold and 3-fold during machine milking and hand stripping, and was significant for machine milking (P<0.05, 17.32, 47.86, 18.13 ng/l, respectively). Milk-ejection-related cortisol release was visible only in treatment MF. For treatments O and M, prolactin concentration increased prior to the increase in oxytocin. The stripping yield was higher, and fat content in the stripping yield significantly lower, for treatment O indicating incomplete milking. Thus buffaloes are easily disturbed even by small changes in milking routines.

Chronic oxytocin treatment causes reduced milk ejection in dairy cows.

The major milk fraction stored in the bovine udder, the alveolar milk, is not available for milk removal before being actively shifted to the cisternal cavities by the milk ejection reflex (Knight et al. 1994; Pfeilsticker et al. 1996). Tactile teat stimulation, provided by the liner throughout milking, causes continuous release of oxytocin from the neuro-pituitary into the blood circulation, which induces myoepithelial contraction and shifting of alveolar milk into the cistern until the end of milking (Bruckmaier et al. 1994; Crowley &amp; Armstrong, 1992; Gorewit et al. 1983; Lefcourt &amp; Akers, 1983). However, milk ejection during machine milking is not complete. A residual milk fraction of 10–30% remains in the udder and is only removed after administration of supraphysiological amounts of oxytocin, usually at least 10 i.u. of oxytocin injected i.v. (Bruckmaier &amp; Blum, 1998). In dairy practice, exogenous oxytocin is often used at high dosages to treat disturbed or incomplete milk ejection. It is reported by farmers and veterinarians that after long-term use of exogenous oxytocin animals become addicted to the treatment and withdrawal of oxytocin causes reduced milk ejection.

Effect of duodenal perfusion of protein on the intake of dairy cows with or without incomplete milking

The protein content of the diet modifies feed intake in lactating dairy cows, but the mechanisms are unclear. The objective of this trial was to determine whether a duodenal perfusion of protein, with or without the expected increase of milk production, plays a role in the feed intake response. Treatments were (C): control perfusion (500 g .d -1 of glucose + 145 g.d -1 of urea); (P): duodenal perfusion of soy-protein isolate (500 g .d -1 ); and (Pim): the same treatment as (P) but with milk yield limited to the control by incomplete milking. Six rumen and duodenal-cannulated cows producing 35 kg.d -1 of milk were assigned in a double 3 〈 3 Latin square design with periods of 4 weeks and inter-periods of 2 weeks. The intake, number and size of the meals, intake duration, chew- ing activities, digestibility (DM, OM, CP, NDF and ADF), molar proportions of volatile fatty acids and ammonia were not significantly affected by protein perfusions (P and Pim) ( P > 0.05). Duode- nal protein perfusion (P) significantly increased ( P < 0.05) milk yield (+ 4.7 kg.d -1 ), protein production (+ 160 g.d -1 ) and protein content of milk (+ 1.8 g .kg -1 ) in comparison to the control perfusion (T). With incomplete milking (Pim), the milk production was the same as in the control but protein con- tent increased (+ 1.9 g .kg -1 ) and fat content decreased (-3.2 g.kg -1 ). Incomplete milking did not reduce intake, suggesting that mechanisms controlling intake and milk production were partly dissociated. dairy cow / intake / protein / incomplete milking

Detection of antimicrobial substances in individual cow and quarter milk samples using Delvotest microbial inhibitor tests.

The use of antibiotic therapy to treat and prevent udder infections of cows during the dry period is a key component of mastitis control in many countries. At the same time, the general public is becoming increasingly aware of potential hazards from antibiotic residues in foods. Consequently, Delvotest Cow Test (Royal Gist-brocades NV, Delft, The Netherlands), an on-farm version of Delvotest P, a microbial inhibitor test for antimicrobials, is being increasingly used by farmers to assess that milk from individual cows is fit for consignment to the bulk tank. Occasional reports of unexplained positive test results have led to suggestions of possible false-positive reactions in milk from individual cows. To investigate the potential causes of such positive test results, three separate investigations were undertaken. In a field survey of unexplained positive reports from farmers, 14 milk samples from six farms that tested positive were all found to contain antibiotic residues. In more formal investigations of individual quarter milk samples from an experimental herd, none of 134 milk samples from midlactation cows yielded positive reactions; for cows that had just calved, 16 of 144 milk samples were positive, and, of those, 13 had somatic cell counts > 4,000,000/ml. Natural inhibitors were responsible for 1 positive reaction, 8 positive reactions were related to incomplete milking, and 7 samples contained beta-lactam antibiotics. Positive reactions caused by antibiotic persisted in individual quarter samples for up to 7 d postcalving compared with 4 d for milk samples from the whole udder. Delvotest was sensitive to cephalonium, the active ingredient of Cepravin Dry Cow (Mallinckrodt Veterinary Ltd., Uxbridge, United Kingdom), which is the market-leading product in the United Kingdom. Test results yielded a partial purple color reaction in the presence of 8 micrograms/kg of cephalonium and a completely purple reaction at 16 micrograms/kg. These results confirm the validity of Delvotest when used to examine composite milk samples from individual cows supplying the United Kingdom dairy industry and suggest that, with proper attention to milk withdrawal periods and complete milking, there is no obvious risk of antibiotic contamination of milk.

A mathematical model for describing and predicting the lactation curve of Merino ewes

AbstractThe milk production of 63 5-year-old Merino ewes was measured over a 16-week period after lambing. The purpose was to find a suitable mathematical model to represent the lactation curve of Merino sheep and to estimate the parameters of the model for an individual ewe from a single data point in early lactation. Three models were considered, the three-parameter Wood model, yn = nb exp(a + en), the four-parameter Morant model, yn = exp(a + bn + en2 + d/n and the six-parameter Grossman model, yn = a1b1 - [tanh2 (b1n - c1))] + a2b2[1 – tanh2 (b2(n -c2,))].The Grossman model was found to be inappropriate for the available data, while there seems to be little difference in the suitability of the other two models. The Wood and Morant models both seem adequate to represent the lactation curve. A pattern in the estimated residuals suggests possible autocorrelations in the errors, but this is inconclusive due to the limited number of data points per animal.The correlation between the estimated parameters of the model and the daily yield measured during the 1st week of lactation enabled us to use linear regression to estimate the lactation curve of an individual animal based on the 1st week's yield. Confidence and prediction intervals for the yield during the rest of the lactation period may then also be constructed. This makes it possible to extend incomplete milk records for use in genetic evaluation, formulation of rations and economic evaluations.

Regulation of intracellular casein degradation by secreted milk proteins

Intracellular degradation of newly synthesised casein was measured by a pulse-chase method in freshly prepared goat mammary explants. After incubation in medium containing l-[5- 3H]proline, explants were washed and cultured again in unlabelled medium containing 5 mM proline; at intervals up to 24 h the amount of radiolabel incorporated in casein was measured. Tissue was obtained in week 33 of lactation after goats had been milked incompletely in one gland (the test gland) for 24 weeks; the contra-lateral (control) gland was milked normally. In explants from the control gland, casein was not degraded during or after secretion: l-[5- 3H]proline incorporated in casein increased to a maximum value which was maintained through the chase period. For four out of five goats, explants from the test gland showed a decrease in total [ 3H]casein radiolabel at 0–4 h of the chase, indicating that a proportion of casein was degraded during secretion. Intracellular casein degradation was also observed when control gland explants were cultured in chase medium containing a goat whey fraction known to inhibit casein production and milk secretion (Wilde, C.J. et al., (1987) Biochem. J. 242, 285–288). This suggests that the greater volume of residual milk left by incomplete milking reduced secretory efficiency, rendering casein susceptible to intracellular degradation, and that this occurred through the action of a secreted milk constituent, which acts as a chemical feedback inhibitor of milk secretion.

Metabolic adaptations in goat mammary tissue during long-term incomplete milking.

Lactating goats were milked incompletely in one gland and normally in the other gland twice daily for 24 weeks. Yields of the incompletely milked glands were adjusted so that a calculated 100 ml milk remained in the gland at the end of milking. On average this residual volume was greater by 7.6% of the total milk volume than that left after normal milking and was 25.9% greater than the capacity of the alveoli. After 24 weeks, the weekly milk yield of the incompletely milked gland was 23.8% lower than that of the other gland (P less than 0.001) when expressed in relation to cell number. The metabolic capacity of secretory cells in the two glands was measured in serial tissue biopsies. Two weeks of incomplete milking had no effect on enzyme activities or metabolic fluxes in the incompletely milked gland, but after 24 weeks the activities of several key enzymes were significantly lower in this gland. This was associated with a reduced rate of synthesis of total protein and casein in explants freshly prepared from the tissue. The rate of lactose synthesis also tended to be lower in explants from the incompletely milked gland. Secretory cell number in the two glands was similar at the end of incomplete milking. The data indicate that incomplete milking over a long period caused partial secretory cellular involution via a local chemical feedback mechanism in the gland.

Methods of measurement of milk yield and composition in nursing mares: a review

This review describes and analyses the most commonly used methods of estimating milk yield of nursing mares : milking without or with oxytocin injection, weighing the foal before and after suckling, dilution of labelled water in foal body water : milking only does not appear to constitute an accurate method. Weighing before and after suckling requires numerous measurements, due to the foal's frequent sucks. Foal body water dilution does not disturb the mother-offspring relationships, but can only be used when -milkis the sole water source for the foal. Conditions of sampling and analysis for milk composition in nursing mares are described; incomplete milking (without oxytocin injection) involves a bias regarding milk fat content because milking is unusual. An oxytocin injection allows evaluation of the composition of secreted milk. The period of mare-foal separation should be short and close to the natural interval between sucks. Milk analysis should take into aceount the composition of mare milk fat and protein; infrared spectrophotometry should be calibrated for mare's milk. . Some of the differences in the Iiterature on milk secretion data can probably be explained by the methods of measurement of milk yield and composition.

Herd management effects on compositional quality

Lactation depends on milk secretion and the storage of the accumulating milk, followed by milk ejection and effective milk removal during milking. Environmental and disease factors may affect each of these stages independently and, thus, alter the milk composition. With normal milking intervals, the secretion of each of the milk constituents is continuous and linear with time. Subsequently, changes in milk composition occur during storage in the udder, mainly through the free movement of water between milk and blood and as a consequence of maintaining their osmotic equilibrium. The changes in composition are greatest in infected glands. The composition of milk varies in different parts of the udder: the fat content is much lower in the milk in the udder and teat sinuses. Following milk ejection, 10 to 20% of the milk is retained and cannot be removed by milking; the fat content of this residual milk will usually exceed 150 g/kg. The dynamics of these changes are complex and, whilst they may bring about large alterations in the composition of the milk obtained at individual milkings, their effect over longer periods is small. Thus, although incomplete milking, changing the milking intervals and increasing the frequency of milking will cause large fluctuations in the composition of milk at individual milkings, their longer-term effects are minor. The main effect of high levels of udder disease will be to reduce the lactose content but the serum protein level will increase and changes will occur in the concentrations of potassium, sodium and chloride ions. The design of milking equipment and the hygiene during farm storage of milk may materially alter the quality of milk for processing, because of lipolysis.

The effect of incomplete milking or of an extended milking interval on the yield and composition of cow's milk

SummaryThe effect of incomplete milking or of an extended milking interval on the yield and composition of cow's milk has been investigated. At the 1st milking after either treatment, the yield of milk was augmented by a carry-over of milk but at the 2nd milking the yield was invariably depressed and then increased until the original yield, or slightly less, was recovered within 5 days. The concentration of lactose and potassium decreased and of sodium, chloride, whey proteins and casein increased during the period of the treatment, and on the resumption of normal milking the original composition was rapidly recovered. The changes in the composition of fat were less clearly defined because of residual milk effects but over the period of the treatment and the succeeding 6 milkings the effect was invariably to increase fat percentage. The differing effects on composition resulted in a more marked effect on the yields of lactose, potassium and casein than on those of sodium, chloride or the whey proteins throughout the treatment and recovery periods. When milk was removed in portions after an extended milking interval there were decreases in the concentrations of lactose and potassium and increases in those of sodium and chloride throughout normal milking. When the residual milk was obtained after an injection of oxytocin the composition of the portions of milk resembled that of the first portions of milk removed from the udder. The possible effects of the treatments on the secretory cells and the permeability of the udder tissue are discussed.

Effect of Incomplete Milking on the Incidence of Udder Irritation and Subsequent Milk Yield of Dairy Cows

Summary Incomplete milking of dairy cows was practiced for ten-day periods to determine its effect on udder irritation and subsequent milk yield. Two or four pounds of milk were left in the udders at each milking. One group of cows was free from all mastitis infections, whereas most of the cows in the second group had persistent mastitis infections other than Streptococcus agalactiae . Each ten-day incomplete milking period was preceded and followed by a seven-day normal milking period. Leaving 4lb of milk in the udder at each milking resulted in a greater permanent reduction in milk yield than did leaving 2lb in the udder. The leucocyte counts, Whiteside ratings, and CMT ratings did not increase during the periods of incomplete milking. The cows with persistent mastitis infections showed higher values for all three indicators of udder irritation than cows free from infections.

Neurohormonal mechanisms in emotional inhibition of milk ejection.

SUMMARY 1. Fifteen lactating rabbits were maintained on a regime of one daily nursing in which litter weights, milk yields and duration of nursing were recorded. 2. Sodium pentobarbitone anaesthesia blocked the milk-ejection reflex and prevented the removal of more than 15% of the full milk yield by the young. Intravenous injection of 50 mU oxytocin regularly restored normal milk removal; 10 and 20 mU did not. 3. In thirty-five out of forty-two experiments in which the does were suckled while under forcible restraint the amount of milk removed was reduced by 20–100%. In twenty-nine cases injection of 50 mU oxytocin restored normal milk removal. In the remaining six experiments this replacement therapy was fully effective only after the does had been anaesthetized. 4. Kymograph records of milk-ejection responses showed that normal milk removal was associated with a reflex milk-ejection response similar to that produced by 50 mU oxytocin, and incomplete milk removal with a reduced (=5 mU oxytocin) or absent milk-ejection response. Where injection of 50 mU oxytocin failed to restore normal milk removal in the conscious animal, the resulting milk-ejection response was reduced by an amount similar to that produced by injection of 1μg adrenaline. 5. The results indicate that, while activation of the sympathetico-adrenal system does occur, the main factor in emotional disturbance of the milk-ejection reflex is a partial or complete inhibition of oxytocin release from the posterior pituitary gland.

The Effect of Incomplete Milking on Chronic Mastitis Caused by Streptococcus Agalactiae

The Effect of Incomplete Milking on Chronic Mastitis Caused by Streptococcus Agalactiae

Drying up Cows and the Effect of Different Methods upon Milk Production

Summary Results of an investigation using 18 cows in which three methods of drying off cows were studied and compared are reported. The methods considered were incomplete milking, intermittent milking, and complete cessation of milking. The data show that complete cessation of milking can safely be recommended as a method for drying off cows producing at least up to 20 pounds daily. Cows can be dried off in less time by this method than by either of the other two methods considered. No significant difference was noted in the quantity or quality of milk in the lactations following the drying up of cows by the three methods used. Attention is called to the probable desirability of not disturbing the re-sorption phenomenon through intermittent or partial milking when drying off cows. Drying off cows through complete cessation of milking conserves leucocytes that may have an important function in resorption.

The Effect of Various Methods for Drying up Cows on the Bacterial and Cell Content of Milk

Summary (1)Studies of the effect of various methods of drying up cows on the bacterial and cell content of the milk are reported. (2)Incomplete, intermittent, incomplete intermittent milking and complete cessation of milking did not appear to have any marked effect on the bacterial or cell counts of the milk in subsequent lactation periods. (3)Intermittent and incomplete milking usually resulted in somewhat higher bacterial and cell counts during such periods but apparently did not produce permanent effects. (4)Complete cessation of milking appeared to give the most satisfactory results. (5)Bacterial counts were usually somewhat lower during the first few milkings following parturition than they were during periods ten days following calving. (6)Bacterial counts were slightly higher immediately following periods of suspended milking, while the cell counts were decidedly higher. (7)The cell counts were generally higher during the colostral period and then became lower as the period of lactation advanced. (8)The average bacterial count of 284 samples of normal, aseptically drawn milk was 658 while the average cell count was 1,252,000 per cubic centimeter.