Primiparous sow behaviour on the day of farrowing as one of the primary contributors to the growth of piglets in early lactation

Large White and Meishan sows differ in maternal ability and early piglet growth. We investigated the relationships between 100 maternal traits, grouped into 11 blocks according to the biological function they describe and litter growth over three successive periods after birth (D0-D1, D1-D3 and D3-D7; D0 starting at the onset of farrowing), as a measure of sow investment in early piglet production. Within- and between-breed variation was exploited to cover a maximum of the variability existing in pig maternal populations. The objective was to quantify the contribution of maternal traits, including functional traits and behavioural traits, to early litter growth. Multivariate analyses were used to depict correlations among traits. A partial least square multiblock analysis allowed quantifying the effect of maternal traits on early growth traits. Partial triadic analyses highlighted how sow behaviour changed with days, and whether it resulted in changes in litter growth. Several behavioural traits (standing activity, reactivity to different stimuli, postural activity) and functional traits (body reserves, udder quality) at farrowing contributed substantially to litter growth from D0 to D7. Sow aggression towards piglets and time spent standing at D0 were unfavourably correlated to D1-D3 litter growth. Time spent lying with udder exposed at D0 was favourably correlated to D1-D3 litter growth. The farrowing duration was negatively correlated to D0-D1 and D1-D3 litter growth. Furthermore, D3-D7 litter growth was positively correlated to feed intake in the same period. Several behavioural traits and some functional traits influence early litter growth. The contribution of sow behaviour was greater in the critical period around farrowing than in later days.

Parity affects mammary development in late-pregnant swine

The goal of this project was to determine whether various measures of mammary development differed between gilts and multiparous sows at the end of gestation. During gestation, Yorkshire × Landrace gilts (n = 19) and sows (second and third gestations, n = 17) were fed one daily meal of a conventional corn-based diet, where the amount fed was based on body weight (BW) and backfat thickness (BF) at mating. On day 110 ± 1 of gestation, a jugular blood sample was obtained from all gilts and sows to measure insulin-like growth factor-1 (IGF-1), glucose, free fatty acids, and urea. On that same day, BW and BF were measured and animals were euthanized. Mammary glands from one side of the udder were dissected for compositional analyses. The fifth gland of the contralateral row of mammary glands was sampled for histology and immunohistochemical localization of Ki67. There was less total parenchyma (1,437.4 vs. 2,004.7 ± 127.1 g; P < 0.001) and total extraparenchymal tissue (1,691.0 vs. 2,407.0 ± 125.3 g; P < 0.001) in mammary glands of gilts compared to those from sows. When these values were expressed per kg BW (226.0 and 284.0 ± 2.7 kg for gilts and sows, respectively), parenchymal mass did not differ (P > 0.10), while extraparenchymal tissue weight tended to be less in gilts than sows (P = 0.07). All components within the parenchyma differed by parity (P < 0.001). Specifically, parenchymal tissue from gilts contained a greater proportion of fat and dry matter (DM), a lower proportion of protein, and lower concentrations of DNA (6.59 vs. 9.35 ± 0.53 mg/g DM) and RNA (7.76 vs. 12.33 ± 0.70 mg/g DM) than that from sows. On the other hand, the circumference of alveolar lumens was greater in gilts than sows (P < 0.001), while the percentage of epithelial cells that were positive for Ki67, a marker of cell proliferation, was greater in sows than gilts (P < 0.05). Circulating concentrations of IGF-1 were greater in gilts than in multiparous sows (45.0 vs. 27.3 ± 2.8 ng/mL, P < 0.001). None of the other blood variables were changed by parity. Results show a marked effect of parity on mammary gland development in swine. At the end of gestation, the mammary glands of gilts had less parenchyma with lower epithelial proliferation than glands from multiparous sows. These differences could alter the response of mammary tissue to various nutritional or endocrine signals. This information is crucial for the development of management strategies designed to maximize sow milk yield.

Supplementation of dietary semen vaccariae extracts to lactating sow diets: effects on the production performance, milk components, and gene expression related to mammogenesis

This study aimed to investigate the effects of dietary semen vaccariae extracts (SVE) on the production performance, colostrum components, and relative gene expression related to mammogenesis of lactating sows. 48 pregnant sows were selected and randomly allocated into four groups, with six replicates and two sows per replicate. The first group was the control (CON), while the other groups received the same diet further supplemented with 1.5, 3.0 and 4.5 g SVE per kg (SV1, SV2 and SV3, respectively). Compared with the control group, (1) the average daily gain was increased (p < 0.05) in SV1, SV2, and SV3 during the 11-21 days and 1-21 days of lactation; (2) the serum insulin-like growth factor-1, insulin, prolactin, and estrogen contents in SV1, SV2, and SV3 were increased (p < 0.05) on the 1st and 21st day of lactation; (3) The plasma Lysine, Threonine, and Tryptophan concentrations were also higher (p < 0.05) in SV1, SV2, and SV3 on the 1st and 21st day of lactation; (4) The milk Lysine, Methionine, Threonine, and Tryptophan concentrations were higher (p < 0.05) in SV1, SV2, and SV3 on the 1st and 21st day of lactation; (5) The milk lactose ratio and milk protein content were increased (p < 0.05) in the groups treated with semen vaccariae on the 1st day of lactation, while the milkfat ratio and milk protein content were increased (p < 0.05) in SV2 and SV3 on the 21st day of lactation; (6) the immunoglobulin M, A, and G contents were increased (p < 0.05) in the groups treated with the semen vaccariae on the first day of lactation; and (7) the relative PRLR, STAT5a, FcRn, CSN2, and LALBA expressions were higher (p < 0.05) in the groups treated with the semen vaccariae on the 1st and 21st day of lactation. In this study, the optimum dosage was 3.0 g/kg semen vaccariae, which increased the average daily gain of piglets, total lactation yield, and serum hormone levels, improved the amino acid levels in plasma, and facilitated the milk quality, up-regulated the relative gene expressions in the mammogenesis.

Review: Physiology and nutrition of late gestating and transition sows

The physiology during late gestation and the transition period to lactation changes dramatically in the sow, especially during the latter period. Understanding the physiological processes and how they change dynamically as the sow approaches farrowing, nest building, giving birth to piglets, and producing colostrum is important because these processes greatly affect sow productivity. Glucose originating from assimilated starch accounts for the majority of dietary energy, and around farrowing, various organs and peripheral tissues compete for plasma glucose, which may become depleted. Indeed, physical activity increases shortly prior to farrowing, leading to glucose use by muscles. Approximately ½ to 1 d later, glucose is also needed for uterine contractions to expel the piglets and for the mammary gland to produce lactose and fat for colostrum. At farrowing, the sow appears to prioritize glucose to the mammary gland above the uterus, whereby insufficient dietary energy may compromise the farrowing process. At this time, energy metabolism in the uterus shifts dramatically from relying mainly on the oxidation of glucogenic energy substrates (primarily glucose) to ketogenic energy supplied from triglycerides. The rapid growth of mammary tissue occurs in the last third of gestation, and it accelerates as the sow approaches farrowing. In the last 1 to 2 wk prepartum, some fat may be produced in the mammary glands and stored to be secreted in either colostrum or transient milk. During the first 6 h after the onset of farrowing, the uptake of glucose and lactate by the mammary glands roughly doubles. Lactate is supplying approximately 15% of the glucogenic carbon taken up by the mammary glands and originates from the strong uterine contractions. Thereafter, the mammary uptake of glucose and lactate declines, which suggests that the amount of colostrum secreted starts to decrease at that time. Optimal nutrition of sows during late gestation and the transition period should focus on mammary development, farrowing performance, and colostrum production. The birth weight of piglets seems to be only slightly responsive to maternal nutrition in gilts; on the other hand, sows will counterbalance insufficient feed or nutrient intake by increasing mobilization of their body reserves. Ensuring sufficient energy to sows around farrowing is crucial and may be achieved via adequate feed supply, at least three daily meals, high dietary fiber content, and extra supplementation of energy.

Review: Improving the performance of neonatal piglets

Newborn piglets have a high incidence of preweaning mortality that is not only associated with low birth weights but also with the presence of intra-uterine growth-restricted (IUGR) piglets. Such IUGR piglets are commonly seen in litters from hyperprolific sows as a result of insufficient placental transfer of nutrients. Nutritional strategies can be used prior to and during gestation to enhance foetal development and can also be implemented in the transition period to reduce the duration of farrowing and increase colostrum yield. Recent findings showed that the energy status of sows at the onset of farrowing is crucial to diminish stillbirth rate. Newborn piglets often fail to consume enough colostrum to promote thermostability and subsequent growth, and this is particularly problematic in very large litters when there are fewer available teats than the number of suckling piglets. One injection of 75 IU of oxytocin approximately 14 h after farrowing can prolong the colostral phase, hence increasing the supply of immunoglobulins to piglets. Nevertheless, assistance must be provided to piglets after birth in order to increase their chance of survival. Various approaches can be used, such as: (1) optimising the farrowing environment, (2) supervising farrowing and assisting newborn piglets, (3) using cross-fostering techniques, (4) providing nurse sows, and 5) providing artificial milk. Although research advances have been made in developing feeding and management strategies for sows that increase performance of their newborn piglets, much work still remains to be done to ensure that maximal outcomes are achieved.

Hyperprolactinemia using domperidone in prepubertal gilts: Effects on hormonal status, mammary development and mammary and pituitary gene expression

Objectives of this experiment were to determine if the domperidone protocol previously used for gestating gilts can also lead to hyperprolactinemia in growing gilts, and to assess the effects of such a protocol on hormonal status, mammary development and gene expression in mammary and pituitary tissue of gilts at puberty. The impact on future lactation performance was also determined. At 75 ± 3 kg body weight (BW), gilts were divided between: 1) controls (CTL), receiving daily intramuscular (IM) injections of canola oil (1.1 mL) for 29 d (n = 41), and 2) treated (DOMP), receiving daily IM injections with 0.5 mg/kg BW of the dopamine receptor antagonist domperidone for 29 d (n = 40). In addition to that daily injection, treated gilts also received twice daily IM injections with 0.5 mg/kg BW of domperidone over the first 3 d of treatment. Fifteen gilts per treatment were sacrificed at 210 ± 5 d of age to collect mammary glands (for compositional analysis and gene expression) and the anterior pituitary (for gene expression). Remaining gilts were bred and allowed to farrow. Blood was sampled at the onset of treatment and on days 14 and 30. Gilts that farrowed were also blood sampled on days 3 and 20 of lactation. Blood was assayed for prolactin (PRL), leptin, insulin-like growth factor 1 (IGF-1), urea, free fatty acids and glucose. Concentrations of PRL increased after 14 d and 30 d of treatment (P < 0.01) and were lesser on day 3 of lactation in DOMP than CTL gilts (P < 0.01). At puberty, there were tendencies (P < 0.10) for total parenchymal protein and DNA to be greater in DOMP than CTL gilts. Treatment did not affect mRNA abundance of PRL or the long form of the PRL receptor genes in the pituitary gland at puberty but expression level of the dopamine receptor D2 and PRL genes was much lower in pubertal than late-pregnant gilts (P < 0.001). Furthermore, many genes related with PRL had a much greater expression level in late pregnancy than at puberty. On day 20 of lactation, CTL sows had greater concentrations of urea than DOMP sows (P < 0.01). The growth rate of litters was not affected by treatment nor was milk composition (P > 0.10). Even though PRL concentrations were increased with treatment, the absence of effect on mammary development was either due to timing relative to developmental stage, whereby treatment was initiated when gilts were too young, or was because all PRL receptors may have been saturated thereby preventing biological action of additional PRL.

Modern, exogenous exposures associated with altered mammary gland development: A systematic review

BACKGROUND

Many women report low milk supply as the reason for premature breastfeeding cessation. Altered mammary gland development may impact a woman's lactation ability.

OBJECTIVE

This review identifies modern exogenous exposures which alter mammary gland development during embryonic life, puberty and pregnancy.

METHODS

A systematic review was undertaken whereby Medline, CINAHL and Embase articles published from January 1, 2005 to November 20, 2020 were searched using the keywords puberty or embry* or fetal or foetal or foetus or fetus or pregnan* or gestation* AND "mammary gland development" or "breast development" or "mammary development" or "mammary gland function" or "mammary function" or "insufficient glandular tissue" or "mammary hypoplasia" or "breast hypoplasia" or "mammary gland hypoplasia" or "tubular breast*" or "tuberous breast*" or "glandular tissue" or "breast composition" or "mammary composition" or "mammary gland composition". After initial screening of 1207 records, 60 full texts were assessed for eligibility; 6 were excluded due to lack of information about exposure or outcome, leaving 54 studies.

RESULTS

The review included results from 52 animal (rats and mice, monkeys, rabbits, sheep, goats pigs and cows) and 2 human studies. Various endocrine disrupting chemicals and an obesogenic diet were found to be associated with altered mammary gland morphology during key development stages.

CONCLUSIONS

To improve lactation outcomes, future studies need to focus on lactation as the endpoint and be conducted in a standardised manner to allow for a more significant contribution to the literature that allows for better comparison across studies.

Review: Mammary gland development in swine: embryo to early lactation

Milk production by the sow is a major factor limiting the growth and survival of her litter. Understanding the process of morphogenesis of the sow's mammary gland and the factors that regulate mammary development are important for designing successful management tools that may enhance milk production. Primordia of the mammary glands are first observable in the porcine embryo at approximately 23 days of gestation. The glands then progress through a series of morphologically distinct developmental stages such that, at birth, each mammary gland is composed of the teat, an organized fat pad and two separate lactiferous ducts each with a few ducts branching into the fat pad. The glands continue to grow slowly until about 90 days of age when the rate of growth increases significantly. The increased rate of mammary gland growth coincides with the appearance of large ovarian follicles and an increase in circulating estrogen. After puberty, the continued growth of the gland and elongation and branching of the duct system into the fat pad takes place in response to the elevated levels of estrogen occurring as part of the estrous cycles. After conception, parenchymal mass of each gland increases slowly during early pregnancy and then grows increasingly rapidly during the final trimester. This growth is in response to estrogen, progesterone, prolactin and relaxin. Lobuloalveolar development occurs primarily during late pregnancy. By parturition, the fat pad of the mammary gland has been replaced by colostrum-secreting epithelial cells that line the lumen of the alveoli, lobules and small ducts. All mammary glands develop during pregnancy, however, the extent of development is dependent on the location of the mammary gland on the sow's underline. The mammary glands undergo significant functional differentiation immediately before and after farrowing with the formation of colostrum and the transition through the stages of lactogenesis. Further growth of the glands during lactation is stimulated by milk removal. Individual glands may grow or transiently regress in response to the intensity of suckling during the initial days postpartum. Attempts to enhance milk production by manipulation of mammary development at stages before lactation generally have met with limited success. A more in depth understanding of the processes regulating porcine mammary gland morphogenesis at all stages of development is needed to make further progress.

Body condition of late pregnant gilts affects the expression of selected adipokines and their receptors in mammary fat and backfat tissues

The impact of body condition in late gestating gilts on gene expression of selected adipokines and their receptors in backfat and mammary fat tissues was studied. The presence of associations between mammary gland composition variables and the mRNA abundance of selected genes and serum concentrations of adiponectin and leptin was also investigated. A total of 45 gilts were selected at mating based on their backfat depth and were allocated to three groups: (1) low backfat (LBF; 12-15 mm; n = 14), (2) medium backfat (MBF; 17-19 mm; n = 15), and (3) high backfat (HBF; 22-26 mm; n = 16). Gilts were fed different amounts of a conventional diet to maintain differences in backfat depth throughout the gestation period. Blood samples were collected at day 109 of gestation to measure adiponectin and leptin serum concentrations. Gilts were slaughtered on day 110 of gestation, and mammary glands were collected to determine mammary composition. Mammary fat and backfat tissues were also sampled to measure the mRNA abundance of selected genes. In mammary fat tissue, there was an effect of body condition on the prolactin (PRL; P = 0.01), adiponutrin (PNPLA3; P < 0.10), and prolactin receptor long form (PRLR-LF; P < 0.10) genes. There was a greater PRL mRNA abundance in mammary fat tissue from HBF than LBF or MBF gilts (P < 0.05). The PNPLA3 mRNA abundance was lower in HBF than in MBF gilts (P < 0.05), and that of PRLR-LF was lower in LBF than in HBF gilts (P < 0.05). In backfat, body condition affected the mRNA abundance of leptin (P < 0.05) and PNPLA3 (P < 0.01), with the greatest expression levels being observed in HBF gilts for both genes. Association analyses suggest a detrimental effect of high circulating leptin concentrations on gilts mammary development, as reflected by the negative correlations between serum leptin and protein percent (r = -0.66, P < 0.01), and concentrations of DNA (r = -0.62, P < 0.01) and RNA (r = -0.60, P < 0.01) in mammary parenchyma. Current results show that body condition of gilts at the end of gestation can affect the expression of adipokines in mammary fat and backfat tissues, with a different regulation of transcript abundance being observed in these two fat depots. Results also suggest that circulating leptin is strongly associated with mammary gland composition of late pregnant gilts, whereas locally synthesized leptin from mammary fat tissue is not.

Nutritional impact on mammary development in pigs: a review

Milk yield is a crucial component of a sow operation because it is a limiting factor for piglet growth rate. Stimulating mammary development is one avenue that could be used to improve sow milk production. A number of studies have shown that nutrition of gilts or sows during the periods of rapid mammary accretion occurring during prepuberty, gestation, and lactation can affect mammary development. The present review provides an overview of all the information currently published on the subject. Various nutritional treatments can bring about increases in mammary tissue weight ranging from 27% to 52%. It was clearly established that feed restriction from 90 d of age (but not before 90 d) until puberty has detrimental effects on mammary development in pigs. Ad libitum feeding during that period increased mammary parenchymal weight by 36% to 52%. Body condition is also important because gilts that were obese (36-mm backfat) or too lean (12- to 15-mm backfat) in late gestation had less developed mammary tissue. Furthermore, overfeeding energy in late gestation seems to be detrimental. On the other hand, increasing energy and protein intakes of sows during lactation was beneficial for development of mammary tissue. Feeding certain plant extracts with estrogenic or hyperprolactinemic properties may also prove beneficial in stimulating mammary development at specific physiological periods. For example, feeding genistein to prepubertal gilts increased parenchymal DNA by 44%. Even though research was carried out on the nutritional control of mammogenesis in pigs, it is evident that much remains to be learned before the best nutritional strategy to enhance mammary development can be developed.

TRIENNIAL LACTATION SYMPOSIUM/BOLFA: Adipokines affect mammary growth and function in farm animals

The essential role of mammary fat pads in mammary growth and morphogenesis was the first indication that biologically active molecules, secreted from adipocytes or other stromal cells, could regulate endocrine cues for growth and function of the mammary gland. The presence of leptin and adiponectin receptors in mammary tissues suggested that locally produced or circulating adipokines could affect mammary growth and function. Herein, we present the current knowledge on the role of adipokines in mammary cell proliferation and differentiation and in lactogenesis and galactopoiesis in farm animals. We also address the role of milk adipokines in the neonate. Accumulating evidence suggests that adipokines could act as metabolic sensors, regulating mammary growth and function in periods of metabolic adaptations such as late pregnancy and early lactation. Indeed, different experiments reported that adiponectin and leptin expression varies according to physiological stages and nutritional status of the animal. The current review also demonstrates that adipokines, such as leptin and adiponectin, are important regulators of the action of lactogenic hormones in the mammary gland. Findings also suggest important roles for adipokines in growth and intestinal maturation of the neonate.

Mammary nutrient uptake in multiparous sows fed supplementary arginine during gestation and lactation

Arginine is the precursor for the synthesis of nitric oxide and may increase mammary plasma flow (MPF), which may in turn increase mammary nutrient uptake. Quantifying mammary nutrient uptake improves our understanding of mammary nutrient metabolism and may potentially allow identification of limiting nutrients for colostrum and milk production. Thus, the objectives of the present study were 1) to study the impact of 25 g/d of crystalline Arg (ARG) on MPF and uptake of nutrients by the mammary glands compared with an isonitrogenous supply of Ala (51 g/d; control [CON]) fed to a total of 8 sows from d 30 of gestation until weaning on d 28 of lactation and 2) to quantify mammary nutrient uptake in late gestation and in early and at peak lactation. Sows were surgically fitted with indwelling catheters on d 76 ± 2 SEM of gestation. -amino hippuric acid (AH) was infused (3.0 mmol/h) in the infusion catheter inserted in the mammary vein, initiated 1 h before the first blood sample at -10, -3, 3, and 17 d in milk (DIM). Blood samples were simultaneously drawn from catheters inserted in the femoral artery and the mammary vein, and the samples were collected in hourly intervals from 0.5 h before to 6.5 h after feeding. Sow milk production was assessed at 3 and 17 DIM. Arterial plasma concentrations of Arg and Ala were increased in ARG and CON sows, respectively ( < 0.01), whereas we did not succeed in detecting a greater MPF in ARG sows ( = 0.30). Arterial-venous differences ( = 0.03) and net mammary flux ( = 0.01) of Ala were increased in CON sows, while the net flux of most other metabolites ( > 0.05) was unaffected by treatment. The mammary extraction of all essential AA was below 13% in late gestation. The average mammary extraction of essential AA at peak lactation was greatest for Leu (51%), while the preprandial extraction was greatest for Lys (57%). The mammary carbon balance (input-output) was negative (-39 ± 12 mol C/d) in early lactation but almost balanced at peak lactation (-13 ± 14 mol C/d), suggesting that mammary fat depots contributed to milk synthesis. In conclusion, we failed to observe an increased MPF and mammary uptake of AA and energy metabolites in ARG-supplemented sows. The mammary extraction rate of essential AA indicated that AA were not limiting for the mammary glands in late gestation, while Lys and Leu appeared to be the 2 most limiting essential AA for milk production at peak lactation.

In vivo measures of mammary development in gestating gilts

Potential links between measures of udder morphology obtained in live pregnant gilts and mammary gland development and composition measured in mammary tissue collected at slaughter were studied. Thirty-three gilts were used. In vivo measures of gland morphology using a tape or ultrasound imaging (parenchymal area measured by ultrasound [AREA]) were obtained on d 108 ± 1 of gestation. Gilts were then slaughtered on d 110 ± 1 of gestation to collect mammary glands for dissection and compositional analyses. The various tape measures were the distance between each teat on one side of the udder (DIST-TEAT), the distance between each teat pair (DIST-PAIR), the length of the udder (sum of all DIST-TEAT), the distance between the base of the teat and the ventral midline section of the udder (MID), and the distance between the base of the teat and the exterior junction of the udder with the abdomen (EXT). The variables MID, DIST-TEAT, DIST-PAIR, and length had very poor correlations with parenchymal weight, extraparenchymal weight, or any of the measured compositional variables. On the other hand, both AREA and EXT were correlated ( < 0.01) with the weight of parenchymal tissue, total parenchymal protein, total DNA, and total RNA. The ultrasound measure AREA and the tape measure EXT were also correlated with each other ( < 0.05). These measures could, therefore, be helpful to estimate mammary development in studies where animals cannot be slaughtered. The tape measure EXT seemed to better reflect the volume of the gland than MID, and it provided as reliable an estimate of parenchymal weight as the measure of parenchymal area using ultrasound while being much easier and cheaper to obtain.

Comparative study on the relations between backfat thickness in late-pregnant gilts, mammary development and piglet growth

The potential relation between body condition of gilts in late-pregnancy and litter BW gain as well as mammary development was studied using 2 sets of data. Gilts either from a commercial herd (Part 1, n = 182) or from a series of trials looking at mammary development (Part 2, n = 172) were separated in 3 groups according to backfat thickness (BF) on d 110 of gestation. Group categorization was similar for Parts 1 and 2 of the study and was: low (LOW), 13.6 ± 1.6 mm (mean ± SD); medium (MED), 17.6 ± 1.0 mm (mean ± SD); and high BF (HIGH), 21.8 ± 1.8 mm (mean ± SD) for Part 1, and LOW, 14.2 ± 1.3 mm (mean ± SD); MED, 18.1 ± 1.0 mm (mean ± SD), and HIGH 23.4 ± 2.6 mm (mean ± SD) for Part 2. The effects of BF group on piglet BW gain (Part 1) or on various mammary gland characteristics (Part 2) were determined using ANOVA. Litters from HIGH sows tended to have a greater lactation BW gain than those from LOW sows (P < 0.10). Sows with HIGH BF had more mammary parenchymal tissue and more total protein and total DNA than MED and LOW sows (P < 0.05), which led to greater total protein and total DNA contents (P < 0.05). There were strong positive correlations (P < 0.0001) between parenchymal weight and total protein, total DNA, and total RNA. Results suggest that it is beneficial for primiparous sows to have greater BF (i.e., 20 to 26 mm) at the end of gestation to achieve optimal mammary development and greater litter BW gain in the subsequent lactation.