Suckling Episodes Research Articles

Suckling behavior, performance, and Kleiber index in calves of different genetic groups under shaded and unshaded environments.

The aim of this study was to evaluate the effect of heat stress on the suckling behavior and performance of Nelore (NE), ½ Nelore × ½ Angus (NA), and ½ Nelore × ½ Pantaneiro (NP) crossbred calves, in environments shaded or unshaded, using the temperature-humidity index (THI) and Kleiber index (KI) equations. Twenty-five animals were evaluated, from 30days of age distributed as follows: 9 NE, 8 NA, and 8 NP calves, from 7:00 A.M. to 5:00 P.M., under shaded and unshaded environments. Data were collected on number of suckling episodes per day (NS), mean suckling duration (MSD), surface body temperature (SBT), THI, weight gain, and KI. THI showed difference (P < 0.05) between environments, being lower in the shaded area. NA cattle had higher SBT (33.00 ± 2.31), differing (P < 0.05) from NE (31.71 ± 1.65) and NP (31.38 ± 1.99), and lower (P < 0.05) suckling activity, suggesting reduced thermal comfort. However, their weight gain and KI were higher, differing (P < 0.05) from the other genetic groups. NE and NP cattle did not differ (P > 0.05) in weight gain and KI. Thus, the results suggest that NA calves, despite the greater thermal discomfort, used thermolysis mechanisms to maintain higher weight gain and feed efficiency (KI) than the other groups. NP showed greater thermal adaptability, in addition to weight gain and KI similar to NE cattle.

Effect of switching sows’ positions during lactation on suckling behaviour and performance of co-mingling piglets

Under natural conditions, piglets have the opportunity to interact with non-littermates before weaning. Nevertheless, in intensive production systems, piglets only have contact with penmates during lactation. Social interactions can be encouraged by removing the barrier between litters whilst the sows are kept in their own crates. However, when piglets are co-mingled at the first days of lactation, studies have shown that a high percentage of them suck with their own mother during all the suckling period, regardless of nipples availability. This study aimed to investigate the effect of switching sows’ positions between early co-mingled litters on suckling episodes, durations and maternal suckling. Eight sows’ pairs were housed in adjacent pens before farrowing. Piglets were socialized by removing the separating barriers between two adjacent pens on day 2 post-farrowing. The position of four sows’ pairs was switched at day 14 post-farrowing (Switched group), while the remaining four sows’ pairs remained in their original crates (Control group). The suckling behaviour of piglets was video recorded during the whole experiment (day 2–23). After sows were switched, a decrease suckling duration was observed in Switched group (P = 0.015), a situation that was also observed when analysing one day before and after the change in position. (P = 0.018). The number of suckling episodes decreased in both groups (P < 0.001) after sows were switched. However, when analysing one day before and after switching the number of suckling episodes increased (P < 0.001). Maternal suckling decrease in both groups after sows were switched (P = 0.013). However, no differences were observed one day before and after the switching of sows. No effect of switching sows’ position was observed on productive parameters of piglets (P > 0.05). The suckling behaviour in early co-mingled piglets slightly change after the sows’ position was switched at an intermediate stage of lactation. A decrease in the suckling duration and an increase in the number of episodes one day after sows were switched probably reflect a momentary confusion of the animals. However, although there may have been operant conditioning at the site of consumption, this was not enough to significantly reduce maternal suckling in contrast with previous literature that separated barriers at the middle of the suckling period, reinforcing the operant conditioning through a greater period of conditioning experience.

Automatic detection of suckling events in lamb through accelerometer data classification

We report on an experimental study aimed at establishing a framework for automated detection of suckling episodes in lamb. Suckling turns out to be an important element of the animal’s behavior, because it occurs early in its development cycle and is directly linked to the fundamental predictors of its success. Our objective was to build an inexpensive, unobtrusive, maintenance-free, and energy-efficient device easily attachable to the lamb that would reliably detect suckling episodes and report them wirelessly to a data collection point. We demonstrate that suckling is characterized by a rather simple and distinguished acceleration signature which makes it possible to detect the event with relatively simple techniques easily implementable within low-end microcontrollers. We propose an algorithm to this end and assess its performance on acceleration data obtained from animals in a farm environment. Our algorithm has been able to detect 95% of all (actual) suckling episodes with less that 10% false indications.

Glycaemic behaviour during breastfeeding in women with Type 1 diabetes.

To describe glycaemia in both breastfeeding women and artificially feeding women with Type 1 diabetes, and the changes in glycaemia induced by suckling. A blinded continuous glucose monitor was applied for up to 6 days in eight breastfeeding and eight artificially feeding women with Type 1 diabetes 2-4 months postpartum. Women recorded glucose levels, insulin dosages, oral intake and breastfeeding episodes. A standardized breakfast was consumed on 2 days. A third group (clinic controls) were identified from a historical database. Carbohydrate intake tended to be higher in breastfeeding than artificially feeding women (P = 0.09) despite similar insulin requirements. Compared with breastfeeding women, the high blood glucose index and standard deviation of glucose were higher in artificially feeding women (P = 0.02 and 0.06, respectively) and in the clinical control group (P = 0.02 and 0.05, respectively). The low blood glucose index and hypoglycaemia were similar. After suckling, the low blood glucose index increased compared with before (P < 0.01) and during (P < 0.01) suckling. Hypoglycaemia (blood glucose < 4.0 mmol/l) occurred within 3 h of suckling in 14% of suckling episodes, and was associated with time from last oral intake (P = 0.04) and last rapid-acting insulin (P = 0.03). After a standardized breakfast, the area under the glucose curve was positive. In breastfeeding women the area under the glucose curve was positive if suckling was avoided for 1 h after eating and negative if suckling occurred within 30 min of eating. Breastfeeding women with Type 1 diabetes had similar hypoglycaemia but lower glucose variability than artificially feeding women. Suckling reduced maternal glucose levels but did not cause hypoglycaemia in most episodes.

Maternal offspring behaviour in Curraleiro Pé Duro naturalized cattle in Brazil

The objective of the present study consisted of describing dam and calf suckling behaviour of Curraleiro Pé Duro cattle. In this study, 38 mother-offspring pairs and one mother-offspring-orphan trio were observed for 10 hours daily during three consecutive days spaced every four months over a period of one year. After identification, the animals were observed under field conditions where calf posture and the number of suckling episodes (NS), mean suckling duration (MSD), total suckling duration per day (TSD) as well as natural weaning of these animals were recorded. The model assessed the effects of calf sex and age as well as feeding time. Suckling episodes (70.6%) had a duration of one to five minutes and the calf that suckled in the inverted parallel position had greater chances of success during suckling (99.5%); the younger animals had a shorter mean suckling duration (4.0±0.6 minutes) than the older ones (7.5±1.2 minutes) but they showed a higher number of suckling episodes (6.29±1.00 vs. 1.33±0.04 feeds in 10 hours for young and older calves). Only the factor age in the first three months was significant for NS, MSD, and TSD; males and females had similar suckling episode length and distribution. While these animals show some traits similar to other cattle breeds such as feeding their calves early in the morning and late in the afternoon, the dams spend large periods of the day away from their calves and suckling is more frequent but for shorter periods of time compared with other breeds. Other unique features such as allo-suckling and formation of day-long crèches are observed in this breed.

Mother–Young Relationships in Sheep: A Model for a Multidisciplinary Approach of the Study of Attachment in Mammals

The onset of maternal responsiveness and the development of mother-young attachment in sheep are under the combined influence of hormonal and sensory stimulations. In the mother, the prepartum rise in oestrogen and vaginocervical stimulation caused by expulsion of the foetus act on the main olfactory system and on hypothalamic regions. This induces maternal care through the central release of oxytocin, modulated by opiates and corticotrophin-releasing hormone. In parallel, activation of the main olfactory network enables the learning of individual lamb odour and maternal attachment. In the neonate, the first suckling episodes and the concomitant activation of the cholecystokinin, opioids and oxytocin systems facilitate the development of a preference for the mother. Gastrointestinal signals activate the brain stem, the hypothalamus and the amygdala. Within 72 h of parturition, the mother-young attachment shifts from proximal to distal recognition based on visual and auditory cues after which vocal cues become more salient. Although olfaction remains a key element in the display of selective maternal nursing, maternal attachment relies on a multisensory mental image of the lamb. These findings support the view that sheep are amongst the most appropriate animal models for the study of maternal and filial attachment in mammals.

Perinatal visceral events and brain mechanisms involved in the development of mother–young bonding in sheep

In sheep the onset of maternal responsiveness and the development of the mutual mother–young bond are under the combined influence of hormonal and visceral somatosensory stimulations. These stimuli are provided in the mother by parturition (via steroids and vaginocervical stimulation) and in the neonate by the first suckling episodes (via cholecystokinin and oro-gastro-intestinal stimulation). In addition, each partner relies on specific chemosensory stimulation for reciprocal attraction: amniotic fluids for the mother, colostrum for the young. In the ewe parturition activates several brain structures to respond specifically to sensory cues emanating from the young. The main olfactory bulbs undergo profound neurophysiological changes when exposed to offspring odors at parturition. Additional activations in the hypothalamus – preoptic area – and the amygdala – medial and cortical nuclei – also contribute to maternal responsiveness and memorization of lamb odors. In the neonate, post-ingestive stimulations activate the brain stem via vagal afferents. Like in the ewe, several regions of the hypothalamus and the amygdala respond to colostrum ingestion suggesting common ground for the integrative neural processes involved in early learning and bonding. This leads to rapid visual and auditory recognition in both partners although olfaction remains important in the ewe to display selective nursing. It is concluded that the biological basis for the development of maternal and filial bonding in sheep presents striking similarities.

Lactation and mother–pup behaviour in the Mediterranean monk seal Monachus monachus: an unusual pattern for a phocid

This paper presents baseline information on maternal behaviour and lactation in the Mediterranean monk seal, with particular focus on the age at which pups are weaned. The study was conducted in the western Saharan population, the only surviving colony of the species. The first moult finished at a mean pup age of 72.3±17 d (N=17) and, in contrast to other taxonomically-related phocids, this process was not associated with weaning. Lactation lasted a mean of 119.4 d (N=9; range: 103–149 d) in the pups that could be monitored until full weaning had taken place. This period almost doubles the maximum lactation length reported in other phocid species. During the first week after birth the mother–pup bond was well developed and mothers always remained with their pups. The time invested in nursing (17%, SD: ±36) and in mother–pup interactions (14%, SD: ±32) was higher during this period than afterwards (8%, SD: ±23 and 4%, SD: ±19, respectively). After the first week, nursing continued but mothers started to leave their pups in order to feed at sea. Weaning occurred gradually. Already since birth, pups were active and mobile, and swam frequently before moulting or weaning occurred. Fostering and milk stealing were common patterns of behaviour for both lactating females and pups. In 26.6% of the suckling episodes observed in mother–pup pairs of known identity, pups suckled from females other than their mothers. Some females nursed more than one pup, at least occasionally, and in some cases a pup was fostered long-term by an alien female. The Mediterranean monk seal exhibits maternal-care characteristics that are more like otarids than phocids. This observation contradicts previous proposals that a short lactation period is a phylogenetic characteristic of phocids. Several of the unusual maternal traits observed may be favoured by year-round access to abundant food supply, availability of breeding sites, and mild climatic conditions. This information should be taken into account when designing conservation strategies for the species and, very particularly, in the implementation of pup rehabilitation programmes.

Nursing and feeding behaviour of confined red deer (cervus elaphus scoticus) in the Mexican highlands*

Red deer (Cervus elaphus scoticus) hinds were confined before parturition in 20 × 30 m earth‐floored pens and offered freshly cut legume‐grass mixed pasture (Experiment 1) or lucerne hay (Experiment 2). In Experiment 1, four hinds were placed in a single pen; all parturitions took place within 24 h. Animals were monitored by a single observer for 24‐h periods twice weekly for 10 weeks. Number of daily suckling episodes increased with age while their duration decreased. Consumption of forage started around the fourth week and, by weaning, calves had spent an average of 105.5 min eating forage and 44.2 min ruminating daily, compared with hinds, which consumed forage for 6.05 h and ruminated for 1.77 h per day. In Experiment 2, 24 hinds and their calves were confined in four pens for 12 weeks. Four observers each monitored the activities of a randomly chosen calf from 0800 to 1330 h and from 1430 to 2000 h. Activities were analysed as proportions of total activity using linear and quadratic regressions. Time spent suckling increased until Day 26 (110 seconds, in a total of three bouts), decreasing to 13 seconds (in a total of eight bouts) by Day 73. Most of the hinds (70%) allonursed (nursing a calf other than its own), some as soon as 2 days post‐partum. Forage consumption by the calves decreased from 37.1 s at 8 days to 12.6 and 17.1 s at 59 and 73 days, respectively. The regression equation for time spent suckling (proportion of total activity) against calf age (days) showed a quadratic effect: y = 0.76 ‐ 0.026 day + 0.00023 day2 (R2 = 0.797), whilst time spent eating forage showed an opposite quadratic trend: y = ‐0.17 + 0.28 day ‐ 0.0002 day2 (R2 = 0.761).

Endocrine profiles during doe-litter separation and the subsequent pregnancy in rabbits

This study was carried out to determine the effects of a transient doe-litter separation on plasma prolactin, LH, FSH, estradiol-17beta and progesterone concentrations before artificial insemination and during the subsequent pregnancy. Control does (n=12) had free access to nursing, whereas separated does (n=12) were kept away from their litters for 48 hours before artificial insemination. Both groups were inseminated on day 11 after parturition. Teat stimulation by suckling caused a high increase in prolactin concentrations in separated does (p < 0.0001). Basal prolactin concentrations were observed in both groups on days 8 and 18 of pregnancy. No effect of the treatment was detected on LH and FSH concentrations during the sampling period. A rise of estradiol-17beta concentrations was observed 48 hours after doe-litter separation, compared to control does and to previous values (p < 0.003). Both groups showed low progesterone concentrations before artificial insemination. Pregnant rabbits in both groups showed increased progesterone concentrations on days 8 and 18 of pregnancy. Lower estradiol-17beta concentrations were observed in control does on day 18 of pregnancy compared with separated rabbits (p < 0.003). The results suggest that a transient separation of nursing does from their litters before artificial insemination may promote high follicular steroidogenesis activity leading to increased estradiol-17beta concentrations. This hormonal change could be a result of several stimulatory actions probably triggered by the absence of suckling episodes and may affect the luteotrophic function during the subsequent pregnancy.

Effects of doe–litter separation on endocrinological and productivity variables in lactating rabbits

The objective of this study was to explore the effects of a doe–litter separation for 48 h before artificial insemination (AI) on various endocrinological and productivity variables determined in 24 doe rabbits. The control group (C) ( n=12) had free access to nursing and the separated group (S) ( n=12) were kept apart form their litters for 48 h prior to AI on day 11 of the lactation period. Lower plasma prolactin (PRL) concentrations were observed 24 h after the doe–litter separation ( P<0.04). The S does had increased plasma oestradiol (E 2) concentrations 48 h after the doe–litter separation, compared with preseparation values of the same group and with C does ( P<0.0001). A higher proportion of does showing high sexual receptivity was observed among the S group compared with the C group ( P<0.05). The suckling episode ranged from 3 to 5 min in S does. Teat stimulation by suckling caused an immediate increase in PRL in S does ( P<0.0001). PRL remained high until 7 h after suckling in S does, compared with C does ( P<0.04). The doe–litter separation resulted in a mean (±S.E.M.) reduction in litter weight of 217 (±22.1) g ( P<0.02). No kits died in either group during the separation period. The litter weight on day 21 after parturition and milk production/doe were not affected by treatment. When analysing the subsequent litters, no differences were observed between S and C does in kindling rate, litter size at birth, number of dead kits/litter, litter size at weaning and number of kits dead from birth to weaning. The results suggest that a transient doe–litter separation causes an increase in the proportion of does showing signs of oestrus and may have a major influence on fertility. These effects may be induced by the absence of suckling episodes together with the higher plasma E 2 and lower PRL concentrations seen in the S does prior to AI.

Pituitary and ovarian response to transient doe-litter separation in nursing rabbits

The effects of a transient doe-litter separation on plasma prolactin, FSH and oestradiol concentrations, as well as the effect on LH response to exogenous GnRH administered at the time of artificial insemination, were determined in nursing rabbits. The effects on fertility, and litter size after parturition, as well as litter survival after doe-litter separation, were also studied. Control does (n = 12) had free access to nursing, whereas biostimulated does (n = 12) were separated from their litters for 48 h before artificial insemination. Plasma prolactin concentrations were decreased 24 h after the doe-litter separation (P < 0.05). The response of prolactin to suckling reached 10 times the basal values measured on day 10 after parturition (P < 0.0001). Increased oestradiol concentrations were found during the 48 h after the doe-litter separation: at 0 h, before artificial insemination (P< 0. 0001), 1.0-2.0 h after artificial insemination (P < 0.001), at 2.5 h (P < 0.05), 3.0 h (P < 0.01), and at 3.5 h (P < 0.05) after artificial insemination. Exogenous GnRH administered at the time of artificial insemination caused a greater LH response in does previously separated from their litters during 48 h (P < 0.01). The transient doe-litter separation did not affect plasma FSH concentrations, fertility, litter size or litter survival. These results suggest that a transient separation of nursing does from their litters before artificial insemination results in a decrease in plasma prolactin concentrations that could promote growth of follicular waves, and high steroidogenesis activity, leading to increased oestradiol concentrations and inducing higher sensitivity of the pituitary gland to exogenous GnRH. These findings associated to the absence of suckling episodes would lead to higher LH response and, therefore, exert a major effect on fertility.

Pituitary and ovarian response to transient doe-litter separation in nursing rabbits

The effects of a transient doe-litter separation on plasma prolactin, FSH and oestradiol concentrations, as well as the effect on LH response to exogenous GnRH administered at the time of artificial insemination, were determined in nursing rabbits. The effects on fertility, and litter size after parturition, as well as litter survival after doe-litter separation, were also studied. Control does (n = 12) had free access to nursing, whereas biostimulated does (n = 12) were separated from their litters for 48 h before artificial insemination. Plasma prolactin concentrations were decreased 24 h after the doe-litter separation (P < 0.05). The response of prolactin to suckling reached 10 times the basal values measured on day 10 after parturition (P < 0.0001). Increased oestradiol concentrations were found during the 48 h after the doe-litter separation: at 0 h, before artificial insemination (P< 0. 0001), 1.0-2.0 h after artificial insemination (P < 0.001), at 2.5 h (P < 0.05), 3.0 h (P < 0.01), and at 3.5 h (P < 0.05) after artificial insemination. Exogenous GnRH administered at the time of artificial insemination caused a greater LH response in does previously separated from their litters during 48 h (P < 0.01). The transient doe-litter separation did not affect plasma FSH concentrations, fertility, litter size or litter survival. These results suggest that a transient separation of nursing does from their litters before artificial insemination results in a decrease in plasma prolactin concentrations that could promote growth of follicular waves, and high steroidogenesis activity, leading to increased oestradiol concentrations and inducing higher sensitivity of the pituitary gland to exogenous GnRH. These findings associated to the absence of suckling episodes would lead to higher LH response and, therefore, exert a major effect on fertility.

Effects of time of suckling during the solar day on duration of the postpartum anovulatory interval in Brahman x Hereford (F1) cows.

Previously published reports have indicated that postpartum anovulatory intervals can be markedly reduced and rebreeding performance enhanced in Bos taurus cows by eliminating nighttime suckling. We sought to confirm this hypothesis by examining the effects of day, nighttime, and ad libitum suckling on suckling behavior of calves, duration of the postpartum anovulatory interval, and pregnancy rates in 45 fall-calving Brahman x Hereford (F1) cows. Beginning on d 9 to 12 postpartum, calves were removed from lactating cows from 0700 to 1900 (Night-Suckled, n = 15) or from 1900 to 0700 (Day-Suckled, n = 15), or remained with their dams continuously (Ad Libitum-Suckled, n = 15). Cows in each group were maintained with fertile Angus bulls from d 10 postpartum until the first normal luteal phase or 100 d postpartum, whichever occurred first. Cows were observed for estrous behavior twice daily, and jugular blood samples were collected twice weekly for the determination of serum progesterone concentration. Mean number of suckling episodes per 24 h was greater (P < .0001) for the Ad Libitum-Suckled group than either Night- or Day-Suckled groups (5.9+/-.42 vs 3.8+/-.14, and 3.9+/-.32, respectively). Hourly analysis of suckling episodes in the Ad Libitum group indicated that they were not skewed toward a particular period, with suckling occurring at a periodicity of 4 to 6 h. Intervals to the first rise in progesterone > or = 1 ng/mL (32+/-2.5, 32+/-4.5, and 31+/-1.7 d, respectively), first normal luteal phase (38+/-3.1, 38+/-3.8, and 37+/-2.5 d, respectively), and first estrus (43+/-3.5, 40+/-3.9, and 36+/-1.1 d, respectively) did not differ (P > .05) among the three groups. Similarly, cumulative pregnancy rates within 100 d after calving did not differ (P > .05). These results in Bos indicus x Bos taurus (F1) cattle do not support the previous conclusions in Bos taurus that eliminating nighttime suckling reduces the postpartum anovulatory interval.

Twenty-four hour patterns of prolactin secretion during lactation and the relationship to suckling and the resumption of fertility hi breast-feeding women

In breast-feeding women prolactin released in response to suckling is essential for the maintenance of lactation. This physiological hyperprolactinaemia is also associated with lactational infertility. However, it is not clear whether there is any direct relationship between changes in prolactin per se and the duration of infertility. To address this question, our study determined the pattern of prolactin secretion in relation to suckling and the return of ovarian activity in the same cohort of breast-feeding women. Blood samples were withdrawn at 10 min intervals for 24 h from 09:00 to 09:00 h at either 4 (n = 9) or 8 weeks (n = 11) post-partum when the women had completely suppressed ovarian activity, at the time of the introduction of supplements to the baby (n = 17), a time associated with reduction of suckling activity, at first menses while still breast-feeding (n = 13) and in the follicular phase (n = 9) of the first menstrual cycle after weaning. During sampling, mothers and babies continued their normal pattern of suckling activity. The pattern of prolactin release was very variable at each stage of lactation, depending on the pattern of suckling. Frequent suckling was associated with elevated prolactin concentrations during the 24 h period throughout lactation. When suckling was less frequent, prolactin concentrations fell to baseline values between breast-feeds, but prolactin was released in response to all suckling episodes. An increase in prolactin concentrations at night, independent of suckling, was only evident once breast-feeding had ceased. The prolactin response to suckling declined significantly only after the return of menses at 33.6 +/- 3.5 weeks post-partum. There was no relationship between the duration of amenorrhoea and the plasma concentrations of prolactin over 24 h, or day or night separately, throughout lactation. However, there was a strong correlation (r = 0.843; P < 0.01) between the timing of the introduction of dietary supplements to the baby and the duration of amenorrhoea. These results suggest that there may be no precise link between the release of prolactin during lactation and the duration of lactational infertility in breast-feeding women.

Experience with milk and an artificial nipple promotes conditioned opioid activity in the rat fetus

Milk promotes activity in the kappa opioid system of the rat fetus and reduced responsiveness in a behavioral bioassay of cutaneous sensitivity. In this study, E20 rat fetuses were presented with an artificial nipple (CS) and intraoral infusions of milk (US) to condition opioid activity. Paired presentations of the CS and US resulted in conditioned changes in perioral cutaneous sensitivity, which was not evident in groups exposed to the CS alone, US alone, or explicitly unpaired presentations of US and CS. Selective opioid antagonists administered between conditioning and testing revealed that reexposure to the nipple resulted in activation of the endogenous opioid system. The nipple promoted activity at mu, not kappa, opioid receptors. Conditioned opioid activity to an artificial nipple in the fetus, which lacks experience with milk or other suckling stimuli, implies that conditioned changes in the endogenous opioid system of the newborn rat may develop quickly during the first suckling episodes.

Effect of antagonists of dopamine and opiates on the basal and GnRH-induced secretion of luteinizing hormone, follicle stimulating hormone and prolactin during lactational amenorrhoea in breastfeeding women

The role of dopamine and opiates in the suckling-induced suppression of gonadotrophin secretion and prolactin release was investigated during lactational amenorrhoea in fully breastfeeding women at 12 weeks post-partum. A total of 26 women, 20 using non-steroidal methods of contraception and six using the progestogen-only pill, Noriday (POP), breastfed their babies on demand at a frequency of 3.6 +/- 0.2 suckling episodes during the 8 h study period while blood samples were collected at 10-min intervals. Five hours after the start of sampling six women were given the dopamine antagonist metoclopramide (10 mg, i.m.) while four women received saline. In a second experiment, six women using nonsteroidal contraception and three women on the POP received an i.v. infusion of the opiate antagonist naloxone (1.6 mg/h) for 2 h, while four women using non-steroidal contraception and three women on the POP were infused with saline. Two hours after the i.m. injection or start of infusion all women were given an i.v. injection of 10 micrograms gonadotrophin releasing hormone (GnRH) and samples were collected for a further 1 h. All samples were assayed for luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin. Plasma concentrations of oestradiol were < 60 pmol/l in all women and they remained amenorrhoeic for at least 10 weeks after the study. Pulsatile release of LH was only observed over the 5 h pre-treatment period in 10 of the 20 non-steroid taking women (1-3 pulses/5 h), and in one of the six women (1 pulse/5 h) on POP.(ABSTRACT TRUNCATED AT 250 WORDS)

The feasibility of suppressing ovarian activity following the end of amenorrhoea by increasing the frequency of suckling

OBJECTIVE: To determine the feasibility of suppressing ovarian activity by increasing the frequency of suckling episodes. METHOD: Prospective study was carried out with 19 exclusively breastfeeding volunteers. Ten subjects (experimental group) increased the suckling episodes by minimum 50% per day from the beginning of the first postpartum menses. Nine controls continued breastfeeding as before. Estradiol, progesterone, LH, FSH and prolactin were measured in blood samples, drawn twice a week up to the second postpartum menses or for 60 days, by RIA. Student's t-test was employed. RESULT: The higher suckling frequency prevented ovulation in 7 of 10 cases examined according to the plasma progesterone concentration (<9.5 nmol/l). Significantly higher average prolactin value could also be found in the experimental group (1038 (527) munits/l vs. 518 (245) munits/l; P < 0.05). CONCLUSION: Results suggest that an earlier initiation of the increase in breastfeeding frequency may delay the resumption of ovulation. Frequent, full time lactation may reduce the risk of pregnancy.

Thyrotrophin‐releasing hormone—a lactation‐promoting agent?

To study the lactational and hormonal responses to nasal administration of thyrotrophin-releasing hormone (TRH) in puerperal women with inadequate lactation. Prospective randomized double-blind placebo-controlled study. 19 puerperal women with inadequate lactation (less than 50% of normal milk yield) on the 5th day postpartum. 10 women were allocated to receive TRH administered by a nasal spray of 1 mg, four times daily, between suckling episodes, for 10 consecutive days starting on day 6 postpartum. Nine women were allocated to receive placebo sprays. Daily milk yield, serum levels of prolactin and thyroid hormones. Before treatment all the women had significant prolactin responses to TRH and suckling stimuli. At the end of 10 days of treatment, milk yield increased significantly in the TRH group from a mean of 142.0 (SD 33.9) to 253.0 (SD 105.3) g/day (P = 0.014). There was no significant change in the placebo group. Basal prolactin levels increased from a mean of 117.4 micrograms/l (SD 45.2) to 173.3 micrograms/l (SD 55.5) (P less than 0.001) in the TRH group whereas in the placebo group prolactin levels decreased from 137.2 (SD 69.5) to 82.0 (SD 37.7) micrograms/l. A further rise in prolactin levels and milk yield was seen in seven women in the TRH group who received a second 10-day course of TRH treatment at their own request. There was no significant change in levels of thyroid stimulating hormone, thyroxine and triiodothyronine during treatment in either of the two treatment groups and no signs of hyperthyroidism. Repeated nasal TRH administration between suckling episodes may improve defective lactation.

Breast-feeding and weaning practices in India

Despite the importance of breastfeeding (BF), there are surprisingly few studies on the subject in India. However, the literature that is available reveals that this practice is almost universal, but many customs surrounding BF and weaning are not conducive to the health of the child. Initiation of BF is generally quite late and colostrum is discarded. Moveover, prelactation feeding is generally unhygienic. Although BF is universal, there are signs that in certain population segments, such as the urban and the educated, the duration of BF is becoming shorter. It is recommended that the infant start to breastfeed preferably within 6 hours of birth. Generally, newborn Indians are breastfed for the 1st time 48 to 72 hours after birth. Successful lactation can be started at this time in India. Prelactation goods include boiled water, tea, sugar, honey, jaggery (a course brown sugar made from palm sap) or glucose with plain water and diluted animal milk. Often the mode of feeding is not hygienic. It is generally good for babies to be exclusively breastfed for 4 months after birth. However, in India, particularly out of the cities, women breastfeed exclusively for up to 8 months and in some cases for 12 months. This delay is a major cause of infant malnutrition. When Indian children are very young (0-3 months) they are usually fed on demand. For children aged 3-6 months, frequency of suckling episodes does not go down significantly among nonworking women; however, it drops considerably among those working women who do not take their children to work. The mean age at which children are given solid supplemental food varies considerably across India. The common solid foods include rice, rice with milk and ghee, biscuits, roti (unleavened bread), and boiled potatoes. 99% of women in urban areas; and 89% of those in rural areas believe that human milk is better than commercial milk or animal milk. It is nutritional and has antibodies. About 1/5 of the rural women said that it is good because it does not coast anything. women are generally unaware of contraceptive properties of breast milk. The duration of lactation foes down to almost 1/2 if the women goes back to work and leaves the child home.