Lactation Research Articles

Mammalian Lactation as a Framework for Teaching Development, Physiology, and Cell Biology for Social Change.

Mammalian lactation is a dynamic process that develops throughout the lifespan of an organism. Here we present a framework for a third semester core course in biology that centers course content on lactation allowing examination of the developmental process as a dynamic whole-body experience involving changes occurring at the molecular, cellular, and organ levels of organization. Inequitable economic, socio- and geopolitical systems structure social determinants of health, affecting rates of breastfeeding in human populations. By integrating content exploring the ways social and biological systems impact breastfeeding rates in human populations, students develop abilities to understand the relationship between science and society throughout the course, a critical core competency for engaging in social change. Importantly, they interrogate social systems while simultaneously learning about many canonical biological processes including how natural selection and constraint have shaped the anatomy, physiology, cell biology, and biochemistry of lactation, how proteins, lipids, and carbohydrates are synthesized, processed, and exported through the endomembrane system in eukaryotes, and how neuronal and hormonal feedback mechanisms regulate milk synthesis and secretion. The course is structured using a flipped-classroom design emphasizing revision and student-self assessment that supports development of biological knowledge, social responsibility, and metacognitive skills. Because mammalian lactation includes fascinating, nuanced, and complex components that cross interdisciplinary boundaries, it provides a wealth of opportunities for faculty to teach developmental biology for social change.

Regulation of LPS-Induced Inflammatory Responses in Bovine Mammary Epithelial Cells via TLR4-Mediated NF-κB and MAPK Signaling Pathways by Lactoferrin.

Lactoferrin (LF), a member of the transferrin family, is widely present in mammalian milk and other secretions, exhibiting anti-inflammatory, antibacterial, and anti-infective properties. Although the biological functions of LF have been extensively studied, there are few reports on its effects and molecular mechanisms concerning bovine mastitis caused by bacterial infection. This study used bovine mammary epithelial cells (BMECs) cultured in vitro as the research model. An inflammatory injury model was established by stimulating BMECs with LPS to investigate whether LF at different concentrations (10, 50, 100, and 200 μg·mL-1) could inhibit the inflammatory response before and after the onset of inflammation. The expression of inflammatory cytokines IL-1β, IL-6, IL-8, and TNF-α at both the gene and protein levels was detected using RT-qPCR and ELISA. Western blotting was employed to evaluate the phosphorylation levels in the inflammatory signaling pathways MAPK/P38/ERK and NF-κB/P65, while RT-qPCR was used to examine the impact on TLR4 receptor gene expression. The results display that pretreatment with LF prior to LPS-induced inflammation in BMECs reduced the expression of inflammatory cytokines IL-1β, IL-6, IL-8, and TNF-α at both the gene and protein levels (p < 0.05). LF also inhibited the phosphorylation of NF-κB/P65 and MAPK/P38/ERK signaling pathways and downregulated TLR4 receptor gene expression (p < 0.05). However, when LF was added after the onset of LPS-induced inflammation, inflammatory cytokine expression and phosphorylation levels in the NF-κB/P65 and MAPK/P38/ERK pathways remained elevated, along with high expression of the TLR4 receptor gene (p < 0.05). These findings show that LF can antagonize LPS-induced inflammatory responses in BMECs and reduce cytokine expression, exhibiting anti-inflammatory effects when administered before inflammation. Conversely, when LF is added post-inflammation, it appears to enhance cytokine expression, potentially promoting the recruitment of more cells or factors to resolve inflammation rapidly. Both effects are mediated through the TLR4 receptor and the NF-κB/P65 and MAPK/P38/ERK signaling pathways.

Mobilisation and replenishment of phosphorus reserves in Bos indicus cows. 2. Mature lactating cows fed diets deficient or adequate in phosphorus

Context Pastures growing on low phosphorus (P) soils are often P deficient, particularly for lactating cows. Aim To examine the effects of P-deficient diets on the performance of lactating multiparous cows. Methods From parturition, mature Bos indicus cross cows (n = 32, initially 474 kg liveweight (LW) and body condition score 3.5) were fed ad libitum for 14 weeks one of four diets: (i) high P (HP-HCa), (ii) low P with low calcium (LP-LCa), (iii) low P with high Ca (LP-HCa), or (iv) the LP-LCa diet with ammonium chloride (LP-LCa+ac). Results Voluntary feed intakes were higher for cows fed the HP-HCa than the three LP diets (23.1 vs 17.4–19.6 g DM/kg LW.day; P &lt; 0.001). The HP-HCa cows gained 0.15 kg LW/day, whereas LP cows lost 0.14–0.51 kg LW/day; P &lt; 0.05). The cows fed LP diets generally maintained milk production and calf growth comparable to that of HP-HCa cows (5.8 kg/day and 0.70 kg/day). The HP-HCa cows retained 6.0–6.4 g P/day from weeks 1–8, but P retention was negligible at week 14. The LP cows mobilised 4.9–9.1 g body P/day. Rib cortical bone shortly after parturition was 634 ± 127 (337–848) μg P/mm2 in the 12th rib, and indicated that the bone P reserves were deficient, marginal and adequate in 27, 37 and 37% of the cows, respectively. During lactation, rib bone P increased 23% in HP-HCa cows, changed little in the LP-LCa and LP-HCa cows (−4 and +7%), and decreased 13% (P &lt; 0.05) in LP-LCa+ac cows. The change in rib cortical bone P during lactation was correlated with this measurement at parturition; the P per unit surface area of rib cortical bone of cows with low bone P at parturition did not change, but in cows with high bone P it decreased up to 16%. Plasma inorganic P averaged 1.49 mmol/L in the HP-HCa cows and &lt;0.8 mmol/L in the LP cows. Plasma Ca, Ca/inorganic P ratio, 1,25-dihydroxy vitamin D3, bone alkaline phosphatase, and carboxy-terminal telepeptides of type 1 collagen increased during lactation (P &lt; 0.05 to P &lt; 0.001) in the LP cows. Conclusions When fed acutely P-deficient diets, mature cows of moderate LW and with body condition scores at parturition generally maintained milk secretion and calf growth by mobilisation of body reserves. Implications The capacity of beef cows to maintain lactation when ingesting P-deficient diets provides opportunities for improved herd management.

Incidence and awareness of dysphoric milk ejection reflex (DMER).

To determine Dysphoric Milk Ejection Reflex (DMER) incidence. Secondary objectives were to describe the symptom profiles and patient characteristics of DMER and assess DMER familiarity. A prospective observational study of people who initiated breastfeeding after delivery between December 2022 and May 2023 at two hospitals in New York. Participants filled out an Initial Survey, assessing prior DMER familiarity, and recurring DMER Symptoms Surveys, assessing symptom presence, severity, and transiency. Medical records were reviewed for patient demographics and clinical history. Descriptive and basic inferential statistics were performed. A p<0.05 was considered statistically significant. Based on the DMER definition utilized, incidence was 26.9 % (n=21), and symptom severity was mostly very mild to moderate. Those with DMER had similar baseline characteristics to those without, apart from a significantly higher rate of having delivered via cesarean section (71.4.0 vs. 33.3 %, p<0.01). Among the 55 patients who completed the initial survey, 61.8 % were unfamiliar with the condition. DMER is described as brief, abrupt, negative emotions experienced by breastfeeding individuals prior to milk letdown. We found that more than 1 in 4 participants screened positive. Future research could better define, quantify, qualify, and publicize this condition to inform clinical practices and facilitate successful breastfeeding relationships.

Production performance and milk composition of late lactation dairy goats fed diets based on silages of four different forage species

The objective of the current trial was to evaluate the effect of feeding four different forage species on milk yield and composition, including protein and fatty acid profiles, in dairy goats. Two grasses (Timothy; mown at early heading, and Italian ryegrass; mown at 25 cm height) and two legumes (Alfalfa and White clover; both mown at 10% bloom) were harvested and conserved as silage. Twelve dairy goats of three different breeds (4 Alpine, 4 Toggenburg, and 4 Saanen) in late lactation were used in a replicated 4 × 4 Latin square design. Goats were offered ad libitum access to the tested forages supplemented with 180 g/d of concentrates based on rolled barley and heat-treated soybean meal. DM intake was lower with timothy, intermediate with ryegrass and white clover, and greater with alfalfa. Milk yield was lower with timothy as compared with the other three silages. Milk fat yield was similar among treatments. Milk CP yield was lower with timothy as compared with the other three silages. Milk N efficiency (N secreted/N intake) was greater with timothy, intermediate with ryegrass, and lower with the two legume silages. The proportion of true protein as a percentage of CP was lower in milk from goats fed legume as compared with grass silages. Proportions of casein and whey protein expressed as percentages of true protein were greater with timothy, intermediate with ryegrass and white clover, and lower with alfalfa. Among grass silages, intake and milk secretion of cis-9, cis-12 cis-15 18:3 was greater with ryegrass than with timothy. As a result, the transfer efficiency from dietary intake to secretion in milk was not different between these two treatments. Fewer differences were observed regarding legume forages, as cis-9, cis-12, cis-15 18:3 intake and milk secretion were similar with alfalfa and white clover. However, the transfer of cis-9, cis-12, cis-15 18:3 from diet to milk was highest when feeding alfalfa. In conclusion, forage species fed to dairy goats influence milk composition in terms of fatty acids and protein fractions, which can potentially impact the nutritive value and technological properties of milk.

Systemic and mammary inflammation and mammary gland development of Holstein dairy cows around dry-off and calving.

This study evaluated systemic and mammary inflammation and the immune cell population and developmental pattern of the mammary gland in Holstein dairy cows transitioning from late lactation to the dry period (LTD, n = 6) and from the dry period to early lactation (DTL, n = 7). All cows were healthy and free of mastitis at enrollment. Mammary biopsies, milk or mammary secretions, and blood samples were collected on d -7, 3, 7, and 15 relative to dry-off and on d -8, 3, 7, and 21 relative to calving. After dry-off, LTD cows had increased circulating concentrations of tumor necrosis factor (TNF)-α, haptoglobin, and fibrinogen, suggesting upregulated inflammation. Protein, SCS, and SNF contents in milk or mammary secretions increased during the early dry period but decreased after calving. In contrast, lactose concentrations in mammary secretions decreased in the early dry period and increased following calving. Skim milk concentrations of TNF-α, IL-10, and haptoglobin increased following dry-off. Consistently, mammary tissue mRNA expression of IL1B and IL10 tended to increase on d 7 and 15 following dry-off, respectively. After calving, mammary alveolar and total cells had higher apoptosis rates. Mammary alveolar, stromal, and total cell proliferation rates peaked on d 7 after dry-off in mammary tissue collected from LTD cows and were greater in the late dry period than early lactation. Mammary mRNA expression of HGF increased on d 7 and 15 after dry-off. Mammary tissue collected in the late dry period had greater gene expression of IGF1, IGF2, PRLR than that collected in early lactation. Mammary tissues collected in the early dry period had greater percentages of CD20+ B lymphocytes, CD172a+ macrophages, and neutrophils than tissues collected during late lactation. Mammary tissues collected in early lactation had greater percentages of CD20+ B lymphocytes, CD3+ T lymphocytes, and CD172a+ macrophages than tissue collected in the late dry period. In conclusion, dairy cows experienced upregulated systemic and mammary inflammation during the early dry period, which warrants further research to elucidate its effect on mammary development. Our data also suggested that the increased mammary growth during the late gestation and early dry periods was mediated by different mechanisms. The concurrent increases in immune cell infiltration and mammary cell proliferation in the mammary gland following dry-off suggest an association between mammary immune responses and growth during the early dry period.

High-fat diet during lactation, as opposed to during adolescence or gestation, programs cardiometabolic and autonomic dysfunctions in adult offspring

The Developmental Origins of Health and Disease (DOHaD) concept has been established for three decades. Many studies have shown that, besides pregnancy, other plastic phases (mainly preconception, lactation, and infancy–adolescence) are also sensitive to environmental changes, including nutritional conditions, that can program health or disease later in life. This study compared the susceptibility of the gestation, lactation and adolescence to a high-fat diet (HFD) intervention to program rats into autonomic nervous system imbalance and cardiometabolic dysfunction in adulthood. Four groups of rats were studied: offspring from mothers exposed to a HFD (35% fat) or a standard chow diet (4.5% fat) during gestation (GEST and CONT groups, respectively), offspring from mothers exposed to the HFD during lactation (LAC), and adolescent rats exposed to the HFD (ADOL). Mothers treated during pregnancy exhibited a higher body mass, but nursing mothers presented the highest food energy intake and higher adiposity. Compared to the other groups, the LAC rats showed increased body mass gain, food energy intake, body fat, glucose intolerance and blood pressure. LAC group also showed increased parasympathetic activity. In contrast, LAC sympathetic nerve activity decreased compared with the other groups. The ADOL group exhibited mostly similar responses but of a smaller magnitude. This suggests that the lactation phase is the most sensitive to HFD programming for cardiometabolic dysfunction in adulthood and that early overnutrition may affect neural connections by altering the autonomic nervous system balance.

Reference intervals for serum prolactin concentrations: analytical and clinical considerations.

Prolactin is a 23kDa protein synthesised and released by lactotrophs located in the anterior pituitary gland. The main function of prolactin is the development of the mammary glands and the production and maintenance of milk secretion during pregnancy and lactation. Prolactin is present in 3 forms in the circulation monomeric, dimeric and macroprolactin which is one of the causes of variability between assay manufacturers. Although most assays have been standardised using the WHO's 3rd international standard there is still considerable variability between commercially available assays and as such laboratories need to establish their own reference intervals. Clinicians use reference intervals to distinguish between healthy and diseased individuals. Direct methods to establish reference intervals are expensive and time consuming and are impractical for most routine clinical laboratories. Indirect methods using the laboratories own data are more commonly used but also have drawbacks. Determination of reference intervals for prolactin is particularly difficult due to various physiological causes for variation in prolactin levels including age, sex and menopause. The presence of macroprolactin, its detection and methods for reporting its presence adds to reference interval determination complexity and harmonisation of these methods may improve clinical care.

Dysphoric Milk Ejection Reflex: Measurement, Prevalence, Clinical Features, Maternal Mental Health, and Mother-Infant Bonding.

Introduction: Dysphoric milk ejection reflex (D-MER) is a condition affecting lactating women, characterized by abrupt emotions of dysphoria that start shortly before or during milk let-down and progress for several minutes. Research on D-MER, especially with quantitative methodology, is minimal. This study aimed to validate an instrument for D-MER-related emotions, examine its prevalence and clinical features, and explore differences in maternal mental health and mother-infant bonding between mothers with and without D-MER. Methods: A total of 711 women up to 12 months postpartum participated in an online cross-sectional study. Participants fulfilled the D-MER Questionnaire (D-MERq), Edinburgh Postnatal Depression Scale, Depression, Anxiety, and Stress Scales, and the Postpartum Bonding Questionnaire. Results: The analysis showed that D-MERq had high reliability and good discriminant and divergent validity. The prevalence of D-MER was 5.9%. For the majority, D-MER manifested intensely, accompanied mostly by agitation- and anxiety-related emotions, and 45% of mothers discontinued breastfeeding due to D-MER. Mothers experiencing D-MER had higher levels of depression, anxiety, stress, previous psychiatric diagnoses, and more mother-infant bonding difficulties compared with mothers without D-MER. Conclusion: These findings demonstrate that D-MERq is a valuable tool with good psychometric properties and suitable for clinical and research use to facilitate early identification and better understanding of this phenomenon. D-MER affects a noteworthy number of women and is associated with impaired mental health, bonding difficulties, and breastfeeding discontinuation. This highlights the importance of health care providers recognizing D-MER to ensure better outcomes and a more positive breastfeeding experience.

Hypoprolactinemia, a neglected endocrine disorder.

This special issue of Reviews in Endocrine and Metabolic Disorders is dedicated to hypoprolactinemia. Prolactin is known for its actions on the mammary gland including development, preparation for postpartum lactation, as well as synthesis and maintenance of milk secretion. However, prolactin has many other physiological effects on reproduction, embryonic and fetal development, homeostasis, neuroprotection, behavior, and immunoregulation. In clinical practice, physiopathology and clinical consequences of increased prolactin secretion are generally well understood, and medical treatment to decrease prolactin levels is available and effective in most cases. Unlike prolactin excess, hypoprolactinemia has been a neglected endocrine disorder and nospecific replacement therapy is commercially available. Prolactin is the only anterior pituitary hormone not addressed by clinical hypopituitarism guidelines. In recent years, human studies have revealed that hypoprolactinemia is associated with metabolic, sexual and neuropsychologic alterations. Therefore, this special issue of Reviews in Endocrine and Metabolic Disorders is aimed to enhance our incomplete understanding of hypoprolactinemia. A total of 17 articles were authored by respected scientists and clinicians from a variety of disciplines including adult and pediatric endocrinology, pathology, gynecology, reproductive medicine, oncology, and neurosurgery.

Production and metabolic responses of Montbéliarde and Holstein cows during periparturient period and a sequential feed restriction challenge

The objective was to compare the production and metabolic responses of 22 Montbéliarde (MONT) and 18 Holstein (HOLS) multiparous cows during the periparturient period, and during a sequential nutritional challenge (SNC), consisting of 4 successive induced short feed restrictions each separated by a refeeding period, to explore breed differences in robustness (ability to maintain lactation function during successive challenges) and resilience (ability to recover after each challenge). Cows were studied from 4 wk before expected calving until 158 ± 9 DIM (mean ± SD). Milk and ECM yields were greater in HOLS than in MONT during both the early (i.e., from calving to wk 10) and mid-lactation (i.e., from wk 18 to 22) periods, whereas BCS was greater in MONT than HOLS. During early lactation, energy balance was lower (5 vs. 16 MJ/d), plasma NEFA (270 vs 163 µM) were greater, for HOLS than MONT, respectively. Cows in third-and-greater lactation secreted more ECM, and had delayed resumption of luteal activity compared with second lactation cows. The SNC started at 87 ± 9 DIM and consisted of a sequence of 4 4-d periods of feed restriction (FR), during which feed allowance was calculated to meet 50% of individual energy requirements (FR1, FR2, FR3, FR4), each of them being followed by an ad libitum intake period. Cows were allowed 10 d of ad libitum intake between FR1 and FR2 to study the recovery and compare it with the recovery following FR4, and 3 d of ad libitum intake between FR2, FR3 and FR4 to study responses to repeated FR. Feed allowance met 59 to 67% of energy requirements during FR1 through FR4, as milk secretion decreased with successive FR. Breed differences in milk secretion persisted throughout the nutritional challenges, but were more pronounced during the first 2 FR: Uncorrected MY was greater for HOLS throughout the entire SNC, whereas ECM and plasma NEFA concentrations and milk fat yield were greater for HOLS than MONT during FR1 and FR2, but not FR3 and FR4, suggesting a reduced ability of HOLS to mobilize and transfer fatty acids into milk with successive FRs, and indicating altered robustness of HOLS to maintain high milk yield. Resilience for ECM yield did not differ between breeds. Cows were able to respond to and recover from the SNC, by decreasing milk secretion during FR, undergoing acute metabolic adaptations to support lactation, and recovering DMI during each refeeding period. Cow rankings for ECM yield were maintained consistently from early lactation throughout the SNC periods (rs = 0.59 to 0.90), suggesting that dairy potential was a major driver of responses during the SNC for both HOLS and MONT.

Tobacco Smoke Exposure and Lactation.

Tobacco smoke exposure remains a significant public health concern, particularly for lactating women and their infants. Despite widespread awareness of the harms of smoking during pregnancy, many women continue to smoke postpartum, directly impacting lactation success and infant health. Studies have shown that nicotine, the primary component of tobacco smoke, inhibits prolactin production and the milk ejection reflex, resulting in a decreased milk supply and poor breastfeeding outcomes. Additionally, the presence of harmful chemicals in tobacco smoke, such as cadmium and lead, can accumulate in breast milk, exposing infants to toxic substances with potential long-term health implications. Maternity professionals play a crucial role in supporting smoking cessation efforts among postpartum women, providing evidence-based counseling, resources, and referrals to cessation programs. This review aims to provide an update for maternity professionals on the effects of tobacco smoke exposure on lactation and breastfeeding outcomes. In this review, we will explore the physiological mechanisms through which tobacco smoke components can interfere with lactation. Furthermore, we will discuss the challenges faced by lactating women who smoke, including increased risk of mastitis, reduced breastfeeding duration, and impaired infant growth and development. Finally, we will highlight emerging research on novel interventions to reduce the adverse effects of tobacco smoke exposure on lactation, including pharmacological treatments and behavioral interventions tailored to postpartum women.

Long-term iodine deficiency and excess inhibit β-casein and α-lactalbumin secretion of milk in lactating rats

Iodine is critical for thyroid hormone synthesis and developmental programming in the first 1000 days of life. The effect of maternal iodine on milk protein secretion remains unknown. We aimed to explore the effect of long-term maternal iodine deficiency and excess on milk protein secretion in lactating rats and its mechanisms preliminarily. Animal models of iodine deficiency and excess were generated by treating Wistar rats a low-iodine diet and deionized water with different potassium iodide concentrations from reproductive age to lactation. Under iodine deficiency, CSN2 and α-LA secretion of milk was inhibited in early and mid-lactation, respectively, and the inhibition of milk CSN2 and α-LA secretion weakened in late lactation. Under iodine excess, milk CSN2 secretion was inhibited in early lactation, and the inhibition of milk CSN2 and α-LA secretion was more pronounced in late lactation. Under iodine deficiency and excess, the concentrations of CSN2 and α-LA and protein expression levels of THRα1, THRβ1, and PRLR in the mammary gland decreased. These results demonstrate the negative impact of long-term maternal iodine malnutrition on milk protein secretion.

Turmeric Topical Application: An effective solution for reducing breast milk secretion delays in new mothers

Background: The problem of low coverage of exclusive breastfeeding is partly influenced by insufficient breast milk production. The percentage of exclusive breastfeeding in infants under six months of age in Central Kalimantan in 2020 was 52.98%. This percentage was among the lowest nationally. In 2021, the coverage of exclusive breastfeeding in infants under six months of age reached 56.8%, and in 2022 it did 60.5%. The figure in 2022 exceeded the set target, but several regencies/cities still had low coverage. Insufficient breast milk supply impacts on the nutritional status of the child. Low breast milk production also arises due to several other factors during breastfeeding, namely late initiation of breastfeeding, long breastfeeding time, sore nipples, breast pain and swelling, and inverted nipples. Aims: The study sought to measure the level of success of turmeric topical application in shortening the time it takes to initiate breast milk secretion. Methods: The study uses a true experimental posttest-only control group design. A subject of 50 mothers having full-term spontaneous deliveries and with normal breasts was used in the study. The sample was divided into two groups: control and intervention groups. The sample was selected using a matching process based on age, parity, and early initiation of breastfeeding. Subjects who met the inclusion criteria were offered whether they were willing to be given turmeric compresses after the delivery process. Subjects who were willing were included in the intervention group and those who were not willing were included in the control group. Age and parity in the intervention group were all taken, while the control group was selected to match the intervention group. The intervention group was given a treatment with a turmeric compress on the breasts for six hours. All participants were then observed for time of breast milk secretion initiation. In this experiment, we didn't perform blinding, but we managed it by having the midwife administer the turmeric compress just once during the delivery process before sending the client home. Following this, we recorded the results, specifically the initial breast milk release in both the intervention and the control group. Results: The average time periods it took to initiate breast milk secretion in the intervention and control groups were 509.96 minutes (8.5 hours) and 1573.76 minutes (26.2 hours), respectively. There was a significant difference (p = 0.023) in the time of breast milk secretion initiation of 1063.8 minutes or 17.73 hours between both groups. Conclusion: Applying a turmeric compress on the breasts of postpartum mothers may shorten the time it takes to initiate breast milk secretion. Received: 05 August 2024, Reviewed: 23 August 2024, Revised: 21 September 2024, Accepted: 13 October 2024.

Studying the relationship of the type of higher nervous activity with the milk productivity of cows

The purpose of the presented research was to study the influence of the type of higher nervous activity (HNA) on the secretion of organic components of milk in various milking conditions. The studies were carried out in 2 periods. The first period was standard, and in the second there was a conditioned stimulus - the presence of an outsider. Black-and-white cows were assigned to four types of higher nervous activity: type 1 - strong, balanced; type 2 - strong, unbalanced; 3 - strong, inert; 4 - weak, inhibitory. In the first period, type 2 cows showed a significant decrease in the amount of milk, fat and glucose, but the mass fraction of protein in milk tended to increase separately for each milking by 0.22 %. The ratio of the mass fraction of protein to the percentage of lactose for two milkings was significantly higher by 0.06, in relation to type 1. In type 3, in general, for two milkings, an increase in lactose by 13.3 g, fat - by 7.0 g was noted, in contrast to the indicators of the first type. Animals of the fourth type tended to reduce milk secretion to 18.3 %. Also, the mass fraction of fat in milk was lower to 0.53 % (P &lt; 0.05) and protein to 0.28 %, and the proportion of lactose in milk, on the contrary, was consistently higher in both milkings by 0.25-0,26 % (P &lt; 0.05). In the second period (with a conditioned stimulus), cows of the second group showed a positive trend towards an increase in the mass fraction of protein in the morning with machine milking by 0.26 % (P &lt; 0.05), and with manual milking by 0.32 % (P &lt; 0.05), in relation to the first group. The mass fraction of fat during machine and manual milking in animals of the second type tended to decrease. In the third group, the indicators of milk of the first streams in the morning were higher by 0.99 % (P &lt; 0.05) - fat, by 0.33 % - protein, by 0.09 % - lactose, in relation to the first type of higher nervous activity. In cows with a weak, inhibitory nervous system, the influence of the conditioned stimulus contributed to a decrease in the ratios of the mass fraction of fat and protein in milk to lactose to 0.14 and 0.09, compared with type 1 cows.

Lactoferrin-Based Heteroprotein Systems, From Their Formation Mechanism, Properties, To Applications.

Lactoferrin (LF) is an important iron-binding glycoprotein found in milk and mucosal secretions. The alkaline lactoferrin can interact with some acidic proteins to form heteroprotein systems with multifunctional properties and a wide range of applications. Lactoferrin can interact with animal and plant proteins mainly through the electrostatic forces, dipolar attraction, and hydrophobic interactions. In this review, the types of heteroprotein complexes formed by the complex coacervation of lactoferrin with other proteins are introduced, including the preparation, structure, and applications. The factors affecting the formation of heteroprotein complexes are described, such as pH, ionic strength, mixing ratio, total protein concentration, and temperature. The issues and challenges in the formation of heteroprotein complexes are also discussed.

Estimation of Genetic Parameters for Milk Production Rate and Its Stability in Holstein Population.

Milk production rate (MPR) refers to the rate of milk secretion per hour (kg/h), calculated from the harvested milk yield and milking interval, and it is considered an appropriate measure to evaluate the production potential of cows. The objective of this study was to estimate the phenotypic and genetic parameters of milk production rate traits. In this study, the milking records of 4760 Holstein cows were collected, and four milk yield traits and six milk production rate traits were defined. The MIXED procedure was used to detect the impacts of non-genetic effects on milk yield and milk production rate traits, including parity, measured season and lactation stage. Variance and covariance components for milk yield and milk production rate traits were estimated using a univariate linear repeatability model. Parity, measurement season and lactation stage had significant effects (p < 0.01) on milk yield, milk production rate and its stability. Milk yield and milk production traits had high heritability, and ranged from 0.25 to 0.39. The stability of milk production rate had low heritability (0.04~0.05). Milk production rate is beneficial for the devolving novel trait in dairy breeding and provides new insights for herd management and genetic selection of production performance of dairy cattle.

Forceful Milk Ejection Reflex and Tongue-Tied Neonates’ Breastfeeding Behaviour

Background: Forceful milk ejection reflex in mothers and tongue-tie in infants often cause breastfeeding difficulties. Our purpose was to observe the breastfeeding behavior of tongue-tied neonates, in the presence of forceful milk ejection of their mother versus tongue-tied infants without forceful milk ejection or in the presence of forceful milk ejection in non-tongue-tied infants. Methods: This is an observational, prospective, cohort study. The study was undertaken at the Lactation Institute, in Cluj-Napoca, Romania, between 2012 and 2018. We studied the breastfeeding behavior of neonates attending the Institute. The study includes 80 tongue-tied new-borns of mothers with forceful milk ejection (Group I), compared with the breastfeeding behavior of 40 tongue-tied neonates of mothers with normal let-down (Group II) and 29 neonates without tongue-tie in the presence of forceful let-down (Group III). Descriptive statistics, including numbers and percentages, and SAS software were utilized. Categorical data are presented as counts and percentages and analyzed with chi-square tests, utilizing R and Python software. Statistical significance was set at p-value ≤ 0.001, in some cases at p-value ≤ 0.05 using a chi-square test, sometimes validating the results with Fisher’s Exact Test. Proportional Analysis and Post-Hoc Analysis (pairwise Z-tests for proportions) were also carried out to demonstrate the frequency of cases. Results: From Group I, the majority (92.50%) were breastfed effectively in the first week, significantly different from infants in Group II (20%), where frenotomy was more frequent (92.50%) and performed mainly for suckling difficulties (86.48%). The difficult latch had a higher percentage in infants in Group II (92.50%). “Reflux-like syndrome” (93.10%), breast refusal (24.13%), and, choking (93.10%) were more frequent in infants in Group III. Conclusions: The majority of tongue-tied infants, whose mothers had early forceful milk ejection, were able to effectively breastfeed after birth. In this cohort, frenotomy might not be necessary or could be postponed. The presence of tongue-tie only, without fast milk flow, led to suckling difficulties and the need for frenotomy. Reflux-like syndrome, choking, and breast refusal were more present in infants without tongue-tie but with fast milk flow.

108 Early colostrum uptake by the newborn requires prepartum initiation of lactogenesis in ungulate species - Sponsored by EAAP

Abstract Due to anatomical characteristics of ungulate placenta types, immunoglobulins (IG) cannot be transferred via the placenta from the maternal to the fetal circulation during pregnancy. Therefore, passive immunization of the newborn ungulate immediately after birth is crucial for its survival. Colostrum, the first milk produced contains immunoglobulins (IG) as well as greater concentrations of several nutrients and bioactive components to provide specific immunity for the first weeks of life as well as an activation of the digestive tract and metabolism through colostral hormones, growth factors, vitamins, and special nutrients such as oligosaccharides. The uptake of colostrum by newborn calves, piglets, or foals within the first few hours after birth requires the availability of colostrum in a sufficiently liquid form. The formation of pre-colostrum starts days or even weeks before parturition, which allows concentrations of IG and other factors far beyond the concentrations in maternal blood circulation. Pre-colostrum components are partially secreted into the alveolar lumen and partially stored in the lactocytes of the mammary gland. These secretions are characterized by increased viscosity and density, which are difficult to harvest by the newborn. Through lactogenesis the secretion of milk components such as lactose is initiated, which causes a considerable water influx into the mammary secretion through an osmotic gradient between maternal blood and mammary secretion. The typical high concentrations of gestagens, mostly progesterone, inhibit the initiation of lactogenesis during pregnancy. A declining gestagen activity is the key signal to initiate a lactogenic prolactin increase and hence milk secretion. Mechanisms and timing of gestagen withdrawal differ considerably among mammalian species. Most species initiate both parturition and lactation through luteolysis (cattle, goat, pig, cat, dog, rabbit, mouse rat). In some species the placenta takes over the main portion of gestagen production (human, sheep, horse). In human, IG are transferred to the fetus during pregnancy, and the start of colostrum secretion only several days after parturition is no problem. In sheep and horses, gestagen secretion during late pregnancy is provided by the placenta. Both of these species are ungulates, and a delayed start of lactogenesis would be critical for the survival of the newborn. Therefore, the placental steroid secretion is subject to characteristic changes in both species towards the end of pregnancy to allow a timely availability of colostrum immediately after birth. At the end of pregnancy, the placenta of sheep produces estrogens at the expense of progesterone, and in horses the less potent dihydroprogesterone is produced instead of progesterone. A considerable variation in the resulting colostrum composition is likely due to the existing wide range of the interval between the commencement of lactogenesis and parturition or due to local regulatory effects at the level of individual glands.

The ABCG2 Transporter Affects Plasma Levels, Tissue Distribution and Milk Secretion of Lumichrome, a Natural Derivative of Riboflavin.

The ABCG2 membrane transporter affects bioavailability and milk secretion of xenobiotics and natural compounds, including vitamins such as riboflavin. We aimed to characterize the in vitro and in vivo interaction of ABCG2 with lumichrome, the main photodegradation product of riboflavin, which has proven in vitro anti-cancer activity and a therapeutical role in antibacterial photodynamic therapy as an efficient photosensitizer. Using MDCK-II polarized cells overexpressing murine Abcg2 and human ABCG2 we found that lumichrome was efficiently transported by both variants. After lumichrome administration to wild-type and Abcg2-/- mice, plasma AUC20-120 min was 1.8-fold higher in Abcg2-/- mice compared with wild-type mice. The liver and testis from Abcg2-/- mice showed significantly higher lumichrome levels compared with wild-type, whereas lumichrome accumulation in small intestine content of wild-type mice was 2.7-fold higher than in Abcg2-/- counterparts. Finally, a 4.1-fold-higher lumichrome accumulation in milk of wild-type versus Abcg2-/- mice was found. Globally, our results show that ABCG2 plays a crucial role in plasma levels, tissue distribution and milk secretion of lumichrome potentially conditioning its biological activity.