Small increases in peripheral noradrenaline inhibit the milk-ejection response by means of a peripheral mechanism

1984 ◽  
Vol 100 (3) ◽  
pp. 337-344 ◽  
Author(s):  
A. M. Lefcourt ◽  
R. M. Akers
Keyword(s):  
Milk Yield ◽  
Bolus Injection ◽  
Fold Increase ◽  
Response To Treatment ◽  
Milk Ejection ◽  
Milk Flow ◽  
Dependent Change ◽  
Peripheral Mechanism ◽  
Oxytocin Release ◽  
Second Peak

ABSTRACT The effects of exogenous noradrenaline on the milk-ejection response were determined for nine Holstein cows. Noradrenaline was injected (0·95 nmol/kg) 15 s after the start of teat stimulation (preparation) or infused (0·13 nmol/kg per min, after bolus injection of 0·47 nmol/kg) starting 10 min before milking for 20 min. Cows were prepared (udder wash and dry) for 1 min before milking. Both injection and infusion resulted in approximately a 3·5-fold increase in peripheral noradrenaline at 1·75 min after the start of milking (baseline noradrenaline 0·83 and 0·89 nmol/l plasma; at 4 min, 2·00 and 3·00 nmol/l). Prolactin release was delayed and oxytocin release enhanced, while milk yield was decreased by 8·6% for both treatments. The maximum rate of milk flow was also depressed by treatment. In contrast, milking time increased for injection and decreased for infusion. In addition, a milk-yield-dependent change in the pattern of milk flow was seen in response to treatment. In medium-yield animals, two distinct milk-flow peaks were apparent and injection delayed the time to the second peak. We conclude that physiologically meaningful increases in peripheral noradrenaline can inhibit milk-ejection response by means of a peripheral mechanism not involving inhibition of release of oxytocin. J. Endocr. (1984) 100, 337–344

Lactational changes in oxytocin release, intramammary pressure and milking characteristics in dairy cows

1991 ◽  
Vol 58 (2) ◽  
pp. 159-169 ◽  
Author(s):  
Harald Mayer ◽  
Rupert Bruckmaier ◽  
Dieter Schams
Keyword(s):  
Dairy Cows ◽  
Milk Yield ◽  
Maximum Flow ◽  
Pressure Increase ◽  
Maximum Pressure ◽  
Early Lactation ◽  
Milk Ejection ◽  
Milk Flow ◽  
Oxytocin Release ◽  
Almost All

SummaryTwo experiments were conducted to investigate possible changes of milking-related oxytocin release (Expt 1) and of intramammary pressure and milking characteristics (Expt 2) throughout entire lactations in German Braunvieh dairy cows. Mean oxytocin concentrations after stimulation at onset of milking increased from 18·3 ± 15·9 to 30·7 ± 24·1 pg/ml in Expt 1 and decreased from 23·9 ± 17·6 to 15·4 ± 9·1 pg/ml in Expt 2, respectively, but remained above the level necessary to elicit complete milk ejection in both trials. Premilking baseline intramammary pressure had its maximum in early lactation until about month 4 and then decreased to ∼50% of its initial level. Ejection pressure followed a similar pattern, but dropped only to ∼75% of its maximum. This was due to the constant elevation of pressure increase, reaching its highest level in late lactation. Time from commencement of stimulation until maximum pressure exceeded 1 min in almost all instances even in early lactation and increased throughout lactation. Despite the normal decrease of milk yield average milk flow fell only slightly while maximum flow rate remained almost constant. Pressure increase, milk yield and milk flow were not different after 1 min and after extended stimulation. Thus there were no indications of a decreasing sensitivity of the milk ejection reflex during lactation, and milking characteristics were positively affected by intense teat stimulation. Suggestions for practical dairying are made.

scholarly journals Milk yield, oxytocin and β-endorphin gradually normalize during repeated milking in unfamiliar surroundings

1996 ◽  
Vol 63 (2) ◽  
pp. 191-200 ◽  
Author(s):  
Rupert M. Bruckmaier ◽  
Hans-Ulrich Pfeilsticker ◽  
Jürg W. Blum
Keyword(s):  
Dairy Cows ◽  
Milk Yield ◽  
Control Level ◽  
Operating Theatre ◽  
Milk Ejection ◽  
Asymptotic Approach ◽  
Blood Samples ◽  
Milk Flow ◽  
Total Milk ◽  
Oxytocin Release

SummaryFor six successive milkings, six dairy cows were relocated immediately before milking to an unfamiliar operating theatre, a procedure previously shown to inhibit oxytocin release and milk ejection. Two control milkings were performed in familiar surroundings. After milk flow had ceased, two i.v. injections of 1 i.u. oxytocin were given to remove the remaining milk. Milk flow was recorded continuously and blood samples were taken every minute during milking and 10 min after milking. During the first milking in unfamiliar surroundings, no oxytocin was released. Thereby, only 13% of the total milk yield, the cisternal milk, was available and the alveolar milk fraction could only be removed after injection of oxytocin. During subsequent relocations oxytocin release steadily increased toward the control level, although the timing of oxytocin release remained delayed as compared with controls. However, the milk fraction available before oxytocin injection increased with increasing number of removals, following an asymptotic approach to control levels. The concentrations of β-endorphin, cortisol (and perhaps also of prolactin) gradually declined with the number of times the animal was moved to unfamiliar surroundings, i.e. hormone concentrations gradually adjusted to control level. During milking, concentrations of prolactin and cortisol increased, while β-endorphin concentrations decreased (except for the first relocation). We conclude that milking-related oxytocin release and therefore milk ejection adapted gradually to repeated relocations to unfamiliar surroundings. This adaptation was inversely related to β-endorphin concentrations, so it is possible that oxytocin release was suppressed by high circulating β-endorphin concentrations.

Machine milking of Ostfriesian and Lacaune dairy sheep: udder anatomy, milk ejection and milking characteristics

1997 ◽  
Vol 64 (2) ◽  
pp. 163-172 ◽  
Author(s):  
RUPERT M. BRUCKMAIER ◽  
GEORG PAUL ◽  
HARALD MAYER ◽  
DIETER SCHAMS
Keyword(s):  
Milk Yield ◽  
Cross Sections ◽  
Ultrasound Measurement ◽  
Delayed Response ◽  
Dairy Sheep ◽  
Milk Ejection ◽  
Flow Curves ◽  
Flow Rates ◽  
Milk Flow ◽  
Oxytocin Release

Mammary cistern anatomy derived from ultrasound measurement, milk ejection in response to exogenous oxytocin and oxytocin release and milking characteristics with and without manual prestimulation in early (months 2–4) and late (months 5–8) lactation were investigated in Lacaune and Ostfriesian dairy ewes. Vertical ultrasound cisternal cross sections of the cisternal cavities did not differ in the two breeds, whereas the cisternal area fraction located lower than the exit into the teat channel was larger in Ostfriesian than in Lacaune sheep. The cisternal area enlarged within 1 min in response to i.v. oxytocin injection, indicating milk ejection. During milking, oxytocin concentrations in Lacaune generally increased dramatically within 0·5 min from the start of prestimulation or milking, whereas only slight or no oxytocin release was detected during milking without prestimulation in Ostfriesian ewes. Prestimulation induced oxytocin release in Ostfriesian sheep within 1–2 min after the start of milking, indicating delayed response to stimulation. Two peaked milk flow curves were observed when oxytocin release and milk ejection occurred only after removal of cisternal milk. This type of milk flow was more frequent in Ostfriesian than in Lacaune ewes and was reduced in both breeds by prestimulation, while the frequency of one peaked milk flow curves increased. During the course of lactation, milk yield, main milk fraction and milk flow rates decreased, while stripping yield was almost unchanged. Although milk yield was similar in both breeds, milk flow was lower and stripping yield was higher in Ostfriesian than in Lacaune ewes. We conclude that milk ejection in ewes occurred in response to elevated oxytocin concentrations. In Ostfriesian ewes reduced and delayed oxytocin response to teat stimulation resulted in milk ejection only during stripping. Therefore, and probably because a larger volume of the cistern was located below the teat exit in the Ostfriesian breed, stripping yield was higher in Ostfriesian than in Lacaune sheep.

Effect of stimulation intensity on oxytocin release before, during and after machine milking

2003 ◽  
Vol 70 (3) ◽  
pp. 349-354 ◽  
Author(s):  
Daniel Weiss ◽  
Alen Dzidic ◽  
Rupert M Bruckmaier
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Threshold Level ◽  
Flow Profile ◽  
Milk Ejection ◽  
Machine Milking ◽  
Milk Flow ◽  
Oxytocin Release ◽  
Stimulation Period ◽  
Stimulation Of

Release of oxytocin (OT) is essential for milk ejection in dairy cows (Lefcourt & Akers, 1983; Bruckmaier & Blum, 1998). During milk ejection, alveolar milk is shifted into the cistern, which causes an increase of intracisternal pressure (Bruckmaier et al. 1994). To initiate maximum milk ejection at the start of milking, increasing OT concentration beyond a threshold level is sufficient (Schams et al. 1983). Increasing OT concentration beyond this threshold has no additional effect on intracisternal pressure, i.e., milk ejection (Bruckmaier et al. 1994). Stimulatory effects of milking by hand or by machine or by suckling are well documented (Gorewit et al. 1992; Bar-Peled et al. 1995; Tancin et al. 1995; Bruckmaier & Blum, 1996). At the start of milking, stimulatory effects of machine milking without pre-stimulation or with a manual pre-stimulation and subsequent machine milking cause the release of comparable amounts of OT (Gorewit & Gassman, 1985; Mayer et al. 1985; Bruckmaier & Blum, 1996), whereas the timing of the applied pre-stimulation is important for the shape of the milk flow curve. Should the pre-stimulation period be too short, or absent altogether, the start of the main milk flow is delayed resulting in a bimodal milk flow profile (Bruckmaier & Blum, 1996). Furthermore, the stimulation of only one teat causes an OT release similar to that caused by stimulation of all four teats (Bruckmaier et al. 2001). However, milk production is greater for hand milking or suckling than for machine milking, possibly owing to higher OT concentrations (Gorewit et al. 1992; Bar-Peled et al. 1995).

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

2005 ◽  
Vol 72 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Chirathalattu S Thomas ◽  
Rupert M Bruckmaier ◽  
Karin Östensson ◽  
Kerstin Svennersten-Sjaunja
Keyword(s):  
Milk Yield ◽  
Fold Increase ◽  
Threshold Level ◽  
Milk Composition ◽  
Direct Application ◽  
Concentration Increase ◽  
Milk Ejection ◽  
Machine Milking ◽  
Murrah Buffaloes ◽  
Cortisol Release

Milking-related release of oxytocin, prolactin, and cortisol was studied following three pre-milking 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 pre-stimulation 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.

ETHANOL AND THE INHIBITION OF OXYTOCIN RELEASE IN LACTATING RATS

1969 ◽  
Vol 62 (3) ◽  
pp. 546-554 ◽  
Author(s):  
Anna-Riitta Fuchs
Keyword(s):  
Mammary Gland ◽  
Dose Level ◽  
Milk Yield ◽  
Complete Inhibition ◽  
Milk Ejection ◽  
Oxytocin Release ◽  
Anaesthetized Rats ◽  
Peripheral Effect ◽  
Higher Doses

ABSTRACT The effect of ethanol on the release of oxytocin in the rat was studied using suckling as the oxytocin releasing stimulus. Milk removal on 30 min suckling by a litter of 8 after 18 h separation from the mother on postpartum day 13–16 was used as a parameter of oxytocin liberation. Under these conditions 25 mU intravenously injected oxytocin permitted normal milk removal in anaesthetized rats, whereas after injection of 10 mU oxytocin only about half of the normal milk yield was obtained. Ethanol in doses varying from 1.0 to 5.0 g/kg was injected intraperitoneally into the dam as 10 to 20 % solution in saline 30 to 60 min before nursing commenced and the milk yield was compared with saline injected control rats. At the dose level of 1.0 g/kg ethanol had no effect on milk removal but 2.0 g/kg caused a significant reduction to about 60 % of normal, and with higher doses a further reduction of the milk yield occurred. At 3.5 g/kg about 14% of normal milk yield was obtained, and at 5.0 g/kg a complete inhibition of milk ejection was observed. Oxytocin administration permitted normal milk removal in all ethanol treated rats indicating that there was no peripheral effect on the mammary gland. The experiments suggest that ethanol inhibits oxytocin release also in the rat.

Inhibition of oxytocin release during repeated milking in unfamiliar surroundings: the importance of opioids and adrenal cortex sensitivity

2002 ◽  
Vol 69 (1) ◽  
pp. 63-73 ◽  
Author(s):  
JULIANA MAČUHOVÁ ◽  
VLADIMIR TANČIN ◽  
WOLF-DIETER KRAETZL ◽  
HEINRICH H. D. MEYER ◽  
RUPERT M. BRUCKMAIER
Keyword(s):  
Endogenous Opioids ◽  
Opioid Antagonist ◽  
Control Group ◽  
Research Station ◽  
Milk Ejection ◽  
Milk Flow ◽  
Oxytocin Release ◽  
And Control ◽  
Naloxone Treatment ◽  
Vaginal Stimulation

The aim of this study was to test if the opioid antagonist naloxone has a beneficial effect on normalization of oxytocin (OT) release during repeated milking of cows in unfamiliar surroundings. One control milking without naloxone treatment in all cows was performed in the familiar parlour. For four successive evening milkings, cows were transported to, and milked in, the operating theatre of the research station without (control group) or with naloxone administration (1 mg/kg BW) (naloxone group) before milking. After cessation of spontaneous milk flow, but not before 3 min of milking, vaginal stimulation was applied for 2 min. After milk flow ceased again, 10 IU of OT was injected intravenously to remove the remaining milk including residual milk. Milk flow was recorded continuously and blood samples were collected via a jugular vein cannula at 1-min intervals from 1 min before the start of milking until i.v. injection of OT. The inhibition of milk ejection and its normalization during repeated milking in unfamiliar surroundings was not influenced by naloxone treatment. Concentrations of cortisol and β-endorphin during control milking and all relocations were similar in the naloxone and control groups, although their concentrations were higher after relocations than in the control. Therefore, a role of endogenous opioids in the inhibition of milk ejection in unfamiliar surroundings could not be demonstrated. In addition, the effect of exogenous ACTH1–24 (8 IU, i.v.) on the release of cortisol related to the response of cows milked in unfamiliar surroundings was studied. Cows with totally inhibited milk ejection in response to vaginal stimulation during milking after first relocation had numerically, but not significantly lower cortisol levels (8·8±3·4 ng/ml; AUC/min) in response to ACTH than did cows with at least partial milk ejection (38·7±12·9 ng/ml). Thus animals with a higher adrenal response to ACTH seemed to have less severe inhibition of milk ejection.

QUANTITATIVE ASPECTS OF RELEASE OF OXYTOCIN BY SUCKLING IN UNANAESTHETIZED RABBITS

1963 ◽  
Vol 44 (4) ◽  
pp. 581-592 ◽  
Author(s):  
Anna-Riitta Fuchs ◽  
Gorm Wagner
Keyword(s):  
Milk Yield ◽  
Essential Role ◽  
Post Partum ◽  
Lactation Period ◽  
Milk Ejection ◽  
Once Daily ◽  
Milk Flow

ABSTRACT A method of estimating oxytocin output following physiological stimuli is described which is applicable to experiments in conscious, undisturbed and unrestrained animals. The method consists of recording the uterine responses in puerperal rabbits with a permanently inserted intrauterine balloon as an index of neurohypophysial activation. Previous work has been confirmed on the essential role of oxytocin in milk ejection in rabbits. Only negligible amounts of milk are obtained by the young without any endogenous or exogenous oxytocin, but normal release of oxytocin can occur in spite of diminished or completely inhibited milk flow. The amount of oxytocin released during suckling depends on the strength of the stimulus in a characteristic fashion, and the strength of stimuli again depends both on the number of young suckling simultaneously and on their physical maturity. In the early puerperium (up to 3–4 days post-partum) each suckling young evokes a response comparable to that of 0.5–1.0 mU of oxytocin injected intravenously, whether suckling alone or together with its litter-mates. Only a few grams of milk are removed by each young at that time. After this period, the suckling of 1 or 2 young separately still elicits the release of only a small amount of oxytocin (1–2 mU), but during suckling of a whole litter from 50 to 100 mU are liberated, which corresponds to 10–15 mU for each young. The full milk yield can only be obtained by each young while suckling simultaneously with the whole litter. The amount of oxytocin released is independent of the duration of suckling, of the quantity of milk available, and of the milk flow. Once lactation has been established, the oxytocin output during suckling on an »once-daily« regime remains fairly constant at least for a large part of the lactation period. It is possible that at the end of the lactating period, the amount secreted during suckling is increased to about 250 mU or even more.

scholarly journals Machine milking of dairy goats during lactation: udder anatomy, milking characteristics, and blood concentrations of oxytocin and prolactin

1994 ◽  
Vol 61 (4) ◽  
pp. 457-466 ◽  
Author(s):  
Rupert M. Bruckmaier ◽  
Chantal Ritter ◽  
Dieter Schams ◽  
Jürg W. Blum
Keyword(s):  
Milk Yield ◽  
Cross Sections ◽  
Dairy Goats ◽  
Milk Ejection ◽  
Blood Concentrations ◽  
Flow Rates ◽  
Machine Milking ◽  
The Third ◽  
Milk Flow

SummaryForty-four goats were milked and milk flow recorded without or with 1 min manual prestimulation in early, mid and late lactation. Ultrasound measurements of cross sections of the whole mammary gland were performed in a water bath. In additional experiments with 15 goats, milk flow was recorded and frequent blood samples were taken for the determination of oxytocin and prolactin concentrations. Milk yield increased from the first to the third lactation and decreased markedly during the course of lactation. Average and peak milk flow rates were closely related to the actual milk yield. The ultrasound cisternal area was 27·4±1·5% of the entire udder half cross section. Milking characteristics were scarcely different without or with prestimulation, although oxytocin was released within 30 s after the start of prestimulation, whereas oxytocin concentrations without prestimulation increased only after the start of milking. Concentrations of prolactin were higher during July and August than in April, and increased similarly with or without prestimulation during milking. In contrast to dairy cows, prestimulation and an opportune release of oxytocin during milking does not significantly influence the course of milk flow in goats, and this is probably because large amounts of cisternal milk allow milk ejection to be induced only after the start of milking without causing bimodal or otherwise reduced milk flow.

scholarly journals Reduced claw vacuum and b-phase during low milk flow does not impact oxytocin release and milking performance

2017 ◽  
Vol 85 (1) ◽  
pp. 70-77
Author(s):  
Anna-Lena Neuheuser ◽  
Ann-Catherine Schwinn ◽  
Olga Wellnitz ◽  
Lorenzo E. Hernández-Castellano ◽  
Rupert M. Bruckmaier
Keyword(s):  
Wall Thickness ◽  
Cross Sections ◽  
Peak Flow ◽  
Milk Ejection ◽  
Flow Curves ◽  
Flow Rates ◽  
Milk Flow ◽  
Oxytocin Release

Oxytocin release, milking characteristics, and teat condition were investigated with reduced claw vacuum and pulsation settings compared to milking at regular settings with or without pre-stimulation. The reduced vacuum and pulsation settings during low milk flow are expected to protect the teat tissue before the occurrence of milk ejection at the start of milking, and at the end of milking during a potential overmilking period, i.e. at a milk flow <200 g/min. Seven cows were machine-milked either after a 60 s manual pre-stimulation, or without pre-stimulation and reduced vacuum and pulsation settings, or at full vacuum and normal pulsation during the start of milking. Plasma oxytocin (OT) concentration increased similarly in response to manual pre-stimulation and to both milking with reduced, or with full vacuum and pulsation settings, however delayed by 1 min if the cluster was attached without pre-stimulation. In all treatments OT concentrations remained elevated throughout milking. Milk flow curves were mostly non-bimodal at milkings after manual pre-stimulation and bimodal at milkings without pre-stimulation. The main milking time was shorter and average milk flow was higher during milking after pre-stimulation, but did not differ between treatments without pre-stimulation. Milk yields and peak flow rates were not affected by treatments. Either reduced or full vacuum settings were again applied during an intended overmilking from 200 to 100 g/min of milk flow towards the end of milk harvest. Pre-milking teat ultrasound cross sections were recorded one day before the experiment started. Post-milking ultrasound cross sections were performed at 15 min after each experimental milking. Teat wall thickness was increased after milking as compared to pre-milking but did not differ among treatments. In conclusion, OT release and milking performance are similar if milking is performed with pre-stimulation, or without pre-stimulation but reduced claw vacuum and b-phase during low milk flow.

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