Milk Ejection Research Articles

Reduced liner-open phase and vacuum instead of prestimulation increase parlor efficiency in dairy cows

Adequate prestimulation is considered a requirement for a fast, gentle, and complete udder emptying at machine milking. Reduced vacuum or reduced liner-open phase of pulsation (or both) may replace prestimulation and consequently reduce work load of the milker and increase parlor efficiency. In the present study we compared 2 milking routines (MR) with manual prestimulation (LPrep = long preparation: 15 s of forestripping, teat cleaning, and stimulation; SPrep = short preparation: 5 s of teat cleaning) followed by 1-min latency period and milking at standard vacuum and pulsation settings (claw vacuum 44 kPa, pulsation rate 60 cycles/min, pulsation ratio 65/35) with 2 MR consisting of 5 s of teat cleaning, immediate cluster attachment and milking at reduced vacuum with or without shortened liner-open phase of pulsation until milk flow exceeded 400 g/min (RP = reduced pulsation: pulsation ratio 30/70, pulsation rate 50 cycles/min, claw vacuum 44 kPa; RPV = reduced pulsation and vacuum: pulsation ratio 30/70, pulsation rate 50 cycles/min, claw vacuum 34 kPa). Cluster detachment was performed at 400 g/min in all MR. Ten Holstein dairy cows were milked twice daily at 14-h and 10-h milking intervals. Milk flow and electrical conductivity (EC) were recorded throughout milking. During the first 2 min of each milking ultrasound cross-section images of the gland cistern of one front quarter were recorded, and 5 min after the end of milking teat tissue thickness of both front teats was measured by using a cutimeter. Most milking characteristics such as total milk yield, average milk flow, and machine-on time reached higher values at 14-h than 10-h milking intervals, but did not differ among MR. However, the occupancy time (time from the first touch of the udder until cluster detachment) was considerably shorter in RP and RPV compared with LPrep and SPrep. Ultrasound cross section areas of the gland cistern were larger in LPrep than in RP and RPV indicating that milk ejection already occurred at cluster attachment in LPrep. This assumption is also supported by the lower EC at cluster attachment in LPrep than in RP and RPV, which was caused by the presence of alveolar milk in the gland cistern after milk ejection. The MR RP and RPV increase parlor efficiency and are work-saving alternatives to MR, which include an adequate prestimulation (LPrep). However, shortening prestimulation to a 5-s teat cleaning followed by a latency period and milking at regular vacuum and pulsation is not adequate to save occupancy time. Because milking was performed at a relatively low vacuum (44 kPa) and at a detachment level of 400 g/min, teat tissue thickness did not differ among MR, and the vacuum reduction in RPV did not cause an additional advantage for teat condition compared with RP.

PENERAPAN PIJAT OKSITOSIN PADA MASA NIFAS UNTUK MEMPERCEPAT INVOLUSI UTERI DAN MELANCARKAN PENGELUARAN ASI

The postpartum period is a vulnerable period for the mother, because at this time the reproductive organs recover after pregnancy and childbirth. If during recovery there are abnormal changes it will cause complications that can threaten the mother's life. About 60% of maternal deaths occur after delivery of which are caused by complications during the puerperium, one of which is bleeding. To prevent postpartum hemorrhage, you can facilitate the mother to do oxytocin massage, oxytocin massage helps the release of the hormone oxytocin which can cause uterine contractions and affect the process of releasing breast milk smoothly. The purpose of this study was to determine the effectiveness of oxytocin massage on uterine involution and milk ejection. This study refers to the results of a case study of comprehensive midwifery care carried out in Subang with a respondent of one postpartum mother with a background of never getting oxytocin massage in her first child pregnancy and not exclusive breastfeeding, in her second child pregnancy when continuous oxytocin massage has been carried out and causes involution. The mother's uterus becomes normal and faster compared to the first child's puerperium and the release of breast milk becomes smooth, so that the mother avoids postpartum hemorrhage and can breastfeed her baby exclusively.

PENINGKATAN EFEKTIFITAS METODE KANGURU TERHADAP KECUKUPAN ASI PADA BAYI CUKUP BULAN DI DESA SUKARAME BARU KEC. KUALUH HULU KAB. LABUHAN BATU UTARA

PENINGKATAN EFEKTIFITAS METODE KANGURU TERHADAP KECUKUPAN ASI PADA BAYI CUKUP BULAN DI DESA SUKARAME BARU KEC. KUALUH HULU KAB. LABUHAN BATU UTARA

The interplay between glutamatergic circuits and oxytocin neurons in the hypothalamus and its relevance to neurodevelopmental disorders.

Oxytocin (OXT) neurons of the hypothalamus are at the center of several physiological functions, including milk ejection, uterus contraction, and maternal and social behavior. In lactating females, OXT neurons show a pattern of burst firing and inter‐neuron synchronization during suckling that leads to pulsatile release of surges of OXT into the bloodstream to stimulate milk ejection. This pattern of firing and population synchronization may be facilitated in part by hypothalamic glutamatergic circuits, as has been observed in vitro using brain slices obtained from male rats and neonates. However, it remains unknown how hypothalamic glutamatergic circuits influence OXT cell activity outside the context of lactation. In this review, we summarize the in vivo and in vitro studies that describe the synchronized burst firing pattern of OXT neurons and the implication of hypothalamic glutamate in this pattern of firing. We also make note of the few studies that have traced glutamatergic afferents to the hypothalamic paraventricular and supraoptic nuclei. Finally, we discuss the genetic findings implicating several glutamatergic genes in neurodevelopmental disorders, including autism spectrum disorder, thus underscoring the need for future studies to investigate the impact of these mutations on hypothalamic glutamatergic circuits and the OXT system.

Effect of Music Therapy on Relaxation and Breastfeeding Anxiety

Clinical nurses on a postpartum unit noted an opportunity to improve patient care during the breastfeeding process. Although breastfeeding is perceived to be a natural physiological process, many postpartum women experience breastfeeding anxiety. Maternal anxiety decreases the milk production by inhibiting the milk ejection reflex. The 8A’s evidence-based practice model was used to answer the PICO (P—patient, problem or population; I–intervention; C–comparison, control, or comparator; O—outcome(s)) question.

The Importance of Experimental Investigation of the Peripheral Oxytocin System.

Oxytocin and oxytocin receptors are synthesized in the periphery where paracrine/autocrine actions have been described alongside endocrine actions effected by central release of oxytocin from the posterior pituitary. In the female reproductive system, classical actions of uterine contraction and milk ejection from mammary glands are accompanied by actions in the ovaries where roles in steroidogenesis, follicle recruitment and ovulation have been described. Steroidogenesis, contractile activity, and gamete health are similarly affected by oxytocin in the male reproductive tract. In the cardiovascular system, a local oxytocinergic system appears to play an important cardio-protective role. This role is likely associated with emerging evidence that peripheral oxytocin is an important hormone in the endocrinology of glucose homeostasis due to its actions in adipose, the pancreas, and the largely ignored oxytocinergic systems of the adrenal glands and liver. Gene polymorphisms are shown to be associated with a number of reported traits, not least factors associated with metabolic syndrome.

Role of Hypocretin in the Medial Preoptic Area in the Regulation of Sleep, Maternal Behavior and Body Temperature of Lactating Rats

Hypocretins (HCRT), also known as orexins, includes two neuroexcitatory peptides, HCRT-1 and HCRT-2 (orexin A y B, respectively), synthesized by neurons located in the postero-lateral hypothalamus, whose projections and receptors are widely distributed throughout the brain, including the medial preoptic area (mPOA). HCRT have been associated with a wide range of physiological functions including sleep-wake cycle, maternal behavior and body temperature, all regulated by the mPOA. Previously, we showed that HCRT in the mPOA facilitates certain active maternal behaviors, while the blockade of HCRT-R1 increases the time spent in nursing. As mother rats mainly sleep while they nurse, we hypothesize that HCRT in the mPOA of lactating rats reduce sleep and nursing, while intra-mPOA administration of a dual orexin receptor antagonist (DORA) would cause the opposite effect. Therefore, the aim of this study was to determine the role of HCRT within the mPOA, in the regulation and integration of the sleep-wake cycle, maternal behavior and body temperature of lactating rats. For that purpose, we assessed the sleep-wake states, maternal behavior and body temperature of lactating rats following microinjections of HCRT-1 (100 and 200 µM) and DORA (5 mM) into the mPOA. As expected, our data show that HCRT-1 in mPOA promote wakefulness and a slightly increase in body temperature, whereas DORA increases both NREM and REM sleep together with an increment of nursing and milk ejection. Taken together, our results strongly suggest that the endogenous reduction of HCRT within the mPOA contribute to the promotion of sleep, milk ejection and nursing behavior in lactating rats.

СЕЛЕКЦИОННО-ГЕНЕТИЧЕСКИЕ ПАРАМЕТРЫ ИНТЕНСИВНОСТИ МОЛОКОВЫВЕДЕНИЯ У КОРОВ

The study of the main technological feature of the Kholmogorsky breed of the Tatarstan type-milk ejection intensity-showed that its increased variability is characterized by high-blood crossbreeds, as well as animals of the Astronaut and Sovering lines. The high and low genetic potential of parental productivity reduces the variability of milk ejection intensity. However, selection for an increase in milk content will not be accompanied by an improvement in the intensity of milk ejection, since the established phenotypic correlation is mainly negative or positive at a low level. In this regard, it is necessary to control both productive and technological characteristics.

Mismothering and remedying the mother-young relationship in stabled dromedary camels

This study aimed to characterize inappropriate maternal behaviours in stabled dromedary camels in order to detect the main causes of calf rejection, and to develop a suitable method to remediate mismothering. A herd of 45 pregnant females was under video surveillance to detect periparturient females. Twelve pregnant dromedary females (6 accepting their newborns and 6 rejecting them 1 h after calving) were selected as experimental subjects. A blood sample was collected during calving to determine cortisol levels. Maternal behaviour at the calving site was assessed during the first hour postpartum. Rejecting dams and their neonates were moved into a confinement enclosure to assess their maternal behaviour over a period of 30 min at 1 h, 6 h, 12 h, 24 h, 48 h, 72 h during confinement and at 7 d postpartum. Five IU of synthetic oxytocin were injected at 8:00, 12:00 and 16:00 to induce milk ejection in rejecting dams and one qualified person collected colostrum. The newborns were fed by holding the bottle of colostrum on the surface of the mother’s udder and keeping body contact between the two animals. Results showed that the duration of parturition was longer in the mothers that rejected their calves (P = 0.04). Such females spent more time in standing position during the calving process (P = 0.01) compared to accepting mothers, had higher plasma cortisol levels (P < 0.01), and gave birth preferentially while standing. Rejecting mothers changed calving sites and displayed head-turning more frequently (P < 0.01 in both parameters) than accepting mothers. Two causes of rejection were identified: dystocia and presence of an alien calf at the birth site. Moreover, a female showed a case of repeated rejecters. During the first hour postpartum, rejecting mothers failed to express good maternal care and moved away from their neonates. In the confinement enclosure, they exhibited attack behaviour toward their calves, displayed low sniffing activity, and emitted mainly high-pitched grunt. Aggression diminished progressively and disappeared (P < 0.0001) on the 2nd day of confinement while sniffing behaviour increased steadily (P = 0.001). The number of high-pitched grunt decreased over time while the number of low-pitched grunt increased over the first 3 days before declining significantly at the end of the confinement period (P < 0.0001). In conclusion, rejecting mothers can be very aggressive towards their own newborns. However, three days of confinement and forced contact with the calf while bottle-feeding it with the mother’s milk was sufficient to alleviate mismothering in dromedaries and establish proper mother-young relationships.

Effects of snack intake during pregnancy and lactation on reproductive outcome in mild hyperglycemic rats

Metabolic disorders, like diabetes, as well as maternal diet, alter nutrient availability in utero, inducing adaptations in the offspring. Whether the effects of maternal hyperglycemia are modulated by diet, however, has yet to be explored. In the current study, we examined this issue by giving females rats, treated neonatally with STZ to induce mild hyperglycemia, and control littermates either ad libitum access to standard chow (Control n = 17; STZ n = 16) or standard chow and snacks (Control-snack n = 18; STZ-snack n = 19) (potato chips and a red fruit-flavored sucrose syrup solution 1.5%) throughout pregnancy and lactation. We hypothesized that the maternal glucose intolerance typically seen in female rats treated neonatally with STZ would be exacerbated by snack intake, and that the combination of snack intake and STZ treatment would lead to alterations in maternal behavior and offspring development. Maternal body weight and food intake were measured daily through pregnancy and lactation and litter weight throughout lactation. At birth, litter size, offspring weight, body length, and anogenital distance were obtained and offspring were classified according to their weight. Measures of nursing and retrieval behavior, as well as exploration in the open field and the elevated plus-maze were also recorded. As predicted, snack intake tended to aggravate the glucose intolerance of STZ-treated rats during pregnancy. Both Control and STZ-treated females that had access to snacks ate more calories and fat, but less carbohydrate and protein than females having access to chow alone. Overall, STZ-treated dams gave birth to fewer pups. Chow-fed STZ females gave birth to a greater proportion of large for pregnancy age pups, whereas dams in the Control-snack group gave birth to a greater proportion of small pups. The birth weight classification of pups born to STZ-snack rats, however, resembled that of the Control chow-fed females. Although all litters gained weight during lactation, litters from snack-fed dams gained less weight regardless of maternal hyperglycemia and did not show catch-up growth by weaning. Overall, STZ rats spent more time nest building, whereas the average inter milk ejection interval was higher in snack-fed females. STZ-snack dams retrieved the complete litter faster than dams in the other groups. Together, these data suggest that when mild hyperglycemic females are given access to snacks throughout pregnancy and lactation their intake is similar to that of Control females given snack access. The combination of hyperglycemia and snack access tended to decrease glucose tolerance in pregnancy, and normalized birth weight classification, but produced few other effects that were not seen as a function of snack intake or hyperglycemia alone. Since birth weight is a strong predictor of health issues, future studies will further investigate offspring behavioral and metabolic outcomes later in life.

Visualising oxytocin neurone activity in vivo: The key to unlocking central regulation of parturition and lactation.

During parturition and lactation, oxytocin neurones in the supraoptic and paraventricular nuclei fire high-frequency bursts of action potentials that are coordinated across the entire population. Each burst generates a large pulse of oxytocin release into the circulation to induce uterine contraction for parturition and mammary duct contraction for milk ejection. Bursts are stimulated by cervical stretch during parturition and by suckling during lactation. However, the mechanisms by which these stimuli are translated into episodic bursts are poorly understood, as are the mechanisms that coordinate bursts across the oxytocin neurone population. An elegant series of experiments conducted in the 1980s and 1990s used serial paired recordings to show that oxytocin neurones do not act as a syncytium during bursts; rather, they start each burst within a few hundred milliseconds of each other but with no distinct "leaders" or "followers". In addition to afferent noradrenergic inputs that relay the systemic stimuli to oxytocin neurones, bursts depend on somato-dendritic oxytocin release within the hypothalamus. Hence, bursts are considered to be an emergent property of oxytocin neurones that is bootstrapped by appropriate afferent stimulation. Although much progress was made using traditional electrophysiological recordings in head-fixed anaesthetised animals, research has effectively stalled in the last few decades. However, the emergence of new technologies to monitor neuronal activity in freely-behaving animals has reinvigorated efforts to understand the biology underpinning burst firing in oxytocin neurones. Here, we report the use of fibre photometry to monitor the dynamics of milk ejection bursts in the oxytocin neurone population of freely-behaving mice. This approach will shed light on the neural mechanisms that control the oxytocin bursts underpinning parturition and lactation.

Plasticity in Intrinsic Excitability of Hypothalamic Magnocellular Neurosecretory Neurons in Late-Pregnant and Lactating Rats.

Oxytocin and vasopressin secretion from the posterior pituitary gland are required for normal pregnancy and lactation. Oxytocin secretion is relatively low and constant under basal conditions but becomes pulsatile during birth and lactation to stimulate episodic contraction of the uterus for delivery of the fetus and milk ejection during suckling. Vasopressin secretion is maintained in pregnancy and lactation despite reduced osmolality (the principal stimulus for vasopressin secretion) to increase water retention to cope with the cardiovascular demands of pregnancy and lactation. Oxytocin and vasopressin secretion are determined by the action potential (spike) firing of magnocellular neurosecretory neurons of the hypothalamic supraoptic and paraventricular nuclei. In addition to synaptic input activity, spike firing depends on intrinsic excitability conferred by the suite of channels expressed by the neurons. Therefore, we analysed oxytocin and vasopressin neuron activity in anaesthetised non-pregnant, late-pregnant, and lactating rats to test the hypothesis that intrinsic excitability of oxytocin and vasopressin neurons is increased in late pregnancy and lactation to promote oxytocin and vasopressin secretion required for successful pregnancy and lactation. Hazard analysis of spike firing revealed a higher incidence of post-spike hyperexcitability immediately following each spike in oxytocin neurons, but not in vasopressin neurons, in late pregnancy and lactation, which is expected to facilitate high frequency firing during bursts. Despite lower osmolality in late-pregnant and lactating rats, vasopressin neuron activity was not different between non-pregnant, late-pregnant, and lactating rats, and blockade of osmosensitive ΔN-TRPV1 channels inhibited vasopressin neurons to a similar extent in non-pregnant, late-pregnant, and lactating rats. Furthermore, supraoptic nucleus ΔN-TRPV1 mRNA expression was not different between non-pregnant and late-pregnant rats, suggesting that sustained activity of ΔN-TRPV1 channels might maintain vasopressin neuron activity to increase water retention during pregnancy and lactation.

Vacuum Dynamics as an Alternative Method for Detection of Bimodal Milk Ejection in Dairy Cows

Simple SummaryWe investigated the relationship between vacuum dynamics and milk flow curve characteristics using portable vacuum and milk flow recording devices, respectively, for the assessment of bimodal milk flow curves in dairy cows. For this purpose, we analyzed 241 vacuum and milk flow curve recordings that we collected concomitantly during eight milking center evaluations on five New York dairy farms. We found that vacuum dynamics could be a suitable measure to assess bimodal milk flow curves in dairy cows.The primary objective of our study was to assess the ability of a vacuum recorder to detect the presence of bimodal milk flow curves in dairy cows compared with a portable milk flow meter. In a cross-sectional study, 241 individual cow milking observations were analyzed. We simultaneously collected (1) individual cow vacuum events during milking using portable vacuum recorders, and (2) individual cow milk flow curves by attaching a portable milk flow meter to the same milking unit. Presence of bimodality was assessed with the vacuum recorder visually (BIMVA) and with the gold standard method of a milk flow meter through automatic detection (BIMLA). Kappa statistics revealed moderate agreement between BIMVA and BIMLA [κ, 95% confidence intervals (95% CI) = 0.59 (0.46–0.71)]. Diagnostic test statistics for BIMVA for detection of bimodality indicated moderate performance for sensitivity [0.65 (0.52–0.76)] and positive predictive value [0.71 (0.58–0.82)] and high values for specificity [0.92 (0.87–0.95)] and negative predictive value [0.93 (0.84–0.93)]. We conclude that milking vacuum dynamics are a suitable measure to assess bimodal milk flow curves in dairy cows.

Oxytocin Involvement in Body Composition Unveils the True Identity of Oxytocin.

The origin of the Oxytocin/Vasopressin system dates back about 600 million years. Oxytocin (Oxt) together with Vasopressin (VP) regulate a diversity of physiological functions that are important for osmoregulation, reproduction, metabolism, and social behavior. Oxt/VP-like peptides have been identified in several invertebrate species and they are functionally related across the entire animal kingdom. Functional conservation enables future exploitation of invertebrate models to study Oxt’s functions not related to pregnancy and the basic mechanisms of central Oxt/VP signaling. Specifically, Oxt is well known for its effects on uteri contractility and milk ejection as well as on metabolism and energy homeostasis. Moreover, the striking evidence that Oxt is linked to energy regulation is that Oxt- and Oxytocin receptor (Oxtr)-deficient mice show late onset obesity. Interestingly Oxt−/− or Oxtr−/− mice develop weight gain without increasing food intake, suggesting that a lack of Oxt reduce metabolic rate. Oxt is expressed in a diversity of skeletal muscle phenotypes and regulates thermogenesis and bone mass. Oxt may increases skeletal muscle tonicity and/or increases body temperature. In this review, the author compared the three most recent theories on the effects of Oxt on body composition.

Local administration of bicuculline into the ventrolateral and medial preoptic nuclei modifies sleep and maternal behavior in lactating rats.

The preoptic area (POA) is a brain structure classically involved in a wide variety of animal behavior including sleep and maternal care. In the current study, we evaluate the specific effect of disinhibition of two specific regions of the POA, the medial POA nucleus (mPOA) and the ventrolateral POA area (VLPO) on sleep and maternal behavior in lactating rats. For this purpose, mother rats on postpartum day 1 (PPD1) were implanted for polysomnographic recordings and with bilateral cannulae either in the mPOA or in the VLPO. The rats were tested for sleep and maternal behavior on PPD4–8 after the infusion of the GABA-A antagonist, bicuculline (0, 10 or 30 ng/0.2 µl/side). Infusion of bicuculline into the mPOA augmented retrieving and nest building behaviors and reduced both nursing and milk ejections but had almost no effect on sleep. When bicuculine was microinjected into the VLPO, the rats significantly increase the number of retrievings and mouthings and reduced the nursing time without changes in milk ejections, which was associated with an increase in wakefulness and a reduction in light sleep.Our results show that disinhibition of the mPOA, a key area in the control of maternal behavior, increased active maternal behaviors and reduced nursing without affecting wakefulness or sleep time. In contrast, the enhancement of some active maternal behaviors when the drug was infused into the VLPO, a sleep-promoting area, with a concomitant increase in wakefulness suggests that mother rats devote this additional waking time in the active maternal care of the pups. We hypothesize that maternal behavior changes after bicuculine microinjection into the VLPO are caused by a reduction in the sleep drive, rather than a direct effect on maternal behavior.

Oxytocin receptor induces mammary tumorigenesis through prolactin/p-STAT5 pathway

Oxytocin receptor (OXTR) is involved in social behaviors, thermoregulation, and milk ejection, yet little is known about its role in breast cancer. To investigate the role of OXTR in mammary gland development and tumorigenesis, a transgenic mouse model of OXTR overexpression (++Oxtr) was used. Overexpression of OXTR-induced progressive mammary hyperplasia, unexpected milk production, and tumorigenesis in females. OXTR-induced mammary tumors showed ERBB2 upregulation and mixed histological subtypes with predomination of papillary and medullary carcinomas. OXTR overexpression led to an activation of prolactin (PRL)/p-STAT5 pathway and created a microenvironment that promotes mammary-specific tumorigenesis. PRL inhibitor bromocriptine (Br) could mitigate OXTR-driven mammary tumor growth. The study demonstrates Oxtr is an oncogene and a potential drug target for HER2-type breast cancer.

Milk production process, quality and technological properties of milk for the use of various types of milking machines

Studies have been carried out to evaluate the efficiency of using easy-assembled cow houses in modern milk production technologies for the use of high-productive milking plants of the type ‘Parallel’ and ‘Carousel’ with 32 machines each. It has been established that new types of premises not only provide comfortable conditions for the maintenance of highly productive cows, but also reduce the labor costs for their maintenance and, most importantly, allow the use of modern high-productive milking installations of the type ‘Parallel’ and ‘Carousel’. It has been established that the technology of preparation of cows for milking and milking technology provides more complete display of the milk ejection reflex at the installation of the ‘Parallel’ type. The average intensity of cows’ milk flows at this plant is 30% higher compared to those of the installation of ‘Carousel’ type, which is confirmed by the intensity of milk flow production at the first minute of milking, which is at the level of 2.97 against 1.85 kg min.-1 per installation of ‘Carousel’ type. Milk obtained using a milking installation of the ‘Parallel’ type has higher values of the mass fraction of fat and protein that is associated with the genetic potential of animals. According to physical, chemical and technological properties, milk obtained from milking installations such as ‘Parallel’ and ‘Carousel’ is within the limits of the standards in force. Milk obtained from the use of milking equipment such as ‘Carousel’ has higher electrical conductivity at the level of 4.6 mS cm-3, which is confirmed by a higher level of mastitis disease of cows. Due to bacterial contamination, reductase test and milk clot characteristic, milk obtained using a milk installation of ‘Parallel’ type also has higher quality indicators than the installation of ‘Carousel’ type. But according to the complex of indicators, milk obtained from various technologies of milking refers to the desired cheese-making class.

Pathogen dependent effects of high amounts of oxytocin on the bloodmilk barrier integrity during mastitis in dairy cows.

The reduction of antibiotic use in food producing animals becomes increasingly important. Therefore, suitable alternatives for mastitis treatment in dairy cows have to be considered. Oxytocin (OT) induces milk ejection and hence supports milk removal from infected mammary quarters. Beyond udder emptying, the injection of very high dosages of OT causes increased somatic cell counts (SCC) in milk and enables the transfer of immunoglobulins (Ig) from blood into milk through a reduced blood-milk barrier integrity. The aim of the present study was to investigate pathogen-specific changes of SCC, the blood derived milk components lactate dehydrogenase (LDH), serum albumin (SA), and IgG in milk of cows suffering from mastitis caused by different pathogens treated with two intravenous injections of high dosages of OT (100 IU). Milk samples from 184 dairy cows from different farms were collected on day1 (day of clinical examination and mastitis diagnosis) and on days2, 3, 14, and 28. Bacteriological examination (day1) identified involved pathogens. Cows were randomly assigned to treatment (OT injections on days1 and 2) or control group (no OT). Independently of the assigned experimental group, cows received the common therapy protocol of the veterinary practice after sample collection if the general condition was affected. Milk SCC, LDH, SA, and IgG changed specifically depending on involved pathogens. Highest values of all three parameters were measured in mastitis caused by Streptococcus uberis. Changes were less pronounced with other Streptococci spp., Staphylococci spp. or Corynebacterium bovis. Oxytocin treatment did not affect any of the studied parameters independent of the involved pathogen. Only in quarters infected with Staphylococci other than Staphylococcus aureus a decreased SCC and increased IgG concentrations in quarters, where no pathogens were detected, were observed. Thus, high dosage OT administration is obviously not suitable as a stand-alone mastitis treatment in dairy cows.

ON THE MILK EJECTION MECHANISM IN COWS UPON AN INCREASE IN ONE-TIME MILK YIELD

Sympathetic nervous system regulates milk flow through the udder duct system. However, the mechanisms of contraction of the alveoli upon accumulation of different amounts of milk in the udder have not been studied. In the paper, it is found for the first time that the excretion of an increased amount of milk is accompanied by a change in the parameters of the udder blood supply caused by an increase in the contractile response of the alveolar complex. Thus, the goal of the paper is to investigate the contractile reaction of the alveolar complex and lactation in cows with an increased single-milking yield. Nine black-and-white dairy cows of the 2-5th calving were tested, 7 times each, in the first half of lactation (All-Russian Scientific Research Institute of Physiology, Biochemistry and Nutrition of Farm Animals, Kaluga Province). A serial ADU-1 milking machine and a counter sensor (Latvia) were used to record milking parameters. The single-milking yield ranged from 3.4 to 6.7 kg in the control period and was 24.5 % higher (p < 0.001) in the test period. The volumetric blood flow velocity (VBFV) in the udder was assessed by the electromagnetic flowmetry method. A blood flow sensor (Nihon Kohden, Japan) was fixed on the external pudendal artery of the udder. The average VBFV values were recorded for 3 minutes prior to milking (initial period) and in milking. The points characterizing udder blood supply were marked on the VBFV curve, i.e., the beginning of udder irritation, a sharp increase in the blood supply, its maximum and the baseline restoration. The time intervals until a sharp increase in VBFV and an increased blood supply period were calculated. The average and maximum VBFV values and an increase in volumetric blood flow velocity during milking in relation to the initial indicators were determined. The parameters of the udder blood supply were used to assess the contractile response of the alveolar complex. The latent period until milk secretion was determined based on the time from the beginning of udder irritation to a sharp increase in udder blood supply. It was established that the single-milking yield affects the parameters of milking and the udder blood supply. The increased single-milking yield led to a shorter period for removal of the first portion of milk (p < 0.001), an increase in the average intensity (p < 0.001) and maximum intensity (p < 0.001) of milk removal as well as an increase in the machine-milking period (p <0.001). The increased milk secretion was also accompanied by an increase in the udder blood supply. I.e., the period before the udder VBFV increased sharply shortened (p < 0.05), while the average (p < 0.05) and maximum (p < 0.05) VBFV values during milking, as well as period of intensive blood supply to the udder (p < 0.001) increased. The increased blood flow during the test period resulted from an increased contractile response of the myoepithelium and alveoli. The intensive contraction of the alveoli, with the increased contraction amplitude and duration, leads to a shorter latent period. The milk let-down and secretion are under regulation of the sympathetic nervous system. Probably, the excitation of the udder sympathetic nervous system depends on the amount of accumulated milk. The udder tone during milk ejection determines both the alveoli contraction and the rate of milk movement through the milk ducts and its removal through the nipple. The increased udder tone when low filling with milk resulted in a delayed let-down, delayed first portion of milk, low contractile response of the alveoli, and low milk removal. With an increase in the amount of milk in the udder, its tone decreases, resulting in a shorter latent period and faster removal of the first portion of milk, strengthening the contractile response of the alveoli and increasing the intensity of milk removal. Therefore, the latent period of secretion of the first portion of milk can be proposed to characterize the tone of the udder sympathetic nervous system.

О МЕХАНИЗМЕ МОЛОКООТДАЧИ У КОРОВ ПРИ ПОВЫШЕНИИ РАЗОВОГО УДОЯ

Sympathetic nervous system regulates milk flow through the udder duct system. However, the mechanisms of contraction of the alveoli upon accumulation of different amounts of milk in the udder have not been studied. In the paper, it is found for the first time that the excretion of an increased amount of milk is accompanied by a change in the parameters of the udder blood supply caused by an increase in the contractile response of the alveolar complex. Thus, the goal of the paper is to investigate the contractile reaction of the alveolar complex and lactation in cows with an increased single-milking yield. Nine black-and-white dairy cows of the 2-5th calving were tested, 7 times each, in the first half of lactation (All-Russian Scientific Research Institute of Physiology, Biochemistry and Nutrition of Farm Animals, Kaluga Province). A serial ADU-1 milking machine and a counter sensor (Latvia) were used to record milking parameters. The single-milking yield ranged from 3.4 to 6.7 kg in the control period and was 24.5 % higher (p < 0.001) in the test period. The volumetric blood flow velocity (VBFV) in the udder was assessed by the electromagnetic flowmetry method. A blood flow sensor (Nihon Kohden, Japan) was fixed on the external pudendal artery of the udder. The average VBFV values were recorded for 3 minutes prior to milking (initial period) and in milking. The points characterizing udder blood supply were marked on the VBFV curve, i.e., the beginning of udder irritation, a sharp increase in the blood supply, its maximum and the baseline restoration. The time intervals until a sharp increase in VBFV and an increased blood supply period were calculated. The average and maximum VBFV values and an increase in volumetric blood flow velocity during milking in relation to the initial indicators were determined. The parameters of the udder blood supply were used to assess the contractile response of the alveolar complex. The latent period until milk secretion was determined based on the time from the beginning of udder irritation to a sharp increase in udder blood supply. It was established that the single-milking yield affects the parameters of milking and the udder blood supply. The increased single-milking yield led to a shorter period for removal of the first portion of milk (p < 0.001), an increase in the average intensity (p < 0.001) and maximum intensity (p < 0.001) of milk removal as well as an increase in the machine-milking period (p <0.001). The increased milk secretion was also accompanied by an increase in the udder blood supply. I.e., the period before the udder VBFV increased sharply shortened (p < 0.05), while the average (p < 0.05) and maximum (p < 0.05) VBFV values during milking, as well as period of intensive blood supply to the udder (p < 0.001) increased. The increased blood flow during the test period resulted from an increased contractile response of the myoepithelium and alveoli. The intensive contraction of the alveoli, with the increased contraction amplitude and duration, leads to a shorter latent period. The milk let-down and secretion are under regulation of the sympathetic nervous system. Probably, the excitation of the udder sympathetic nervous system depends on the amount of accumulated milk. The udder tone during milk ejection determines both the alveoli contraction and the rate of milk movement through the milk ducts and its removal through the nipple. The increased udder tone when low filling with milk resulted in a delayed let-down, delayed first portion of milk, low contractile response of the alveoli, and low milk removal. With an increase in the amount of milk in the udder, its tone decreases, resulting in a shorter latent period and faster removal of the first portion of milk, strengthening the contractile response of the alveoli and increasing the intensity of milk removal. Therefore, the latent period of secretion of the first portion of milk can be proposed to characterize the tone of the udder sympathetic nervous system.