The ontogeny of nursing in Babyrousa babyrussa and a comparison with domestic pigs

The nursing behavior of eight babirusa (Babyrousa babyrussa) infants was studied. Four were from single births and four were from twin births. The age at weaning, the time of day and number of nursing bouts per day, the mean duration of nursing bouts, and whether the offspring or the dam ended nursing bouts were all examined. It was found that although twins are weaned earlier than single offspring, there were no other statistically significant differences in nursing behavior of single and twin offspring. The ontogeny of nursing behavior in this species is described and some comparisons are made between the nursing behavior of babirusa and nursing in the domestic pig (Sus scrofa) and selected suids. Babirusa dams take longer to wean their offspring, allow them to nurse longer, and end nursing bouts less often than domestic pigs. The differences in behavior between babirusa and domestic pig nursing behavior may be related to differences in the number of offspring produced by the two species and the amount of parental investment in each offspring. Zoo Biol 19:253–262, 2000. © 2000 Wiley‐Liss, Inc.     

When and why are babies weaned?

A prospective study was designed to investigate the weaning practices of 50 primiparous mothers whose babies were born between September 1976 and March 1978. The question whether the age of weaning influenced growth from birth to 6 months was also considered. The mothers and babies were seen in hospital and then at a follow-up clinic at 1, 2, 3, and 6 months. Details were taken of feeding practices, and measurements made of the babies'' weight, length, and subscapular and triceps skinfold thicknesses. Seventeen infants who were breastfed received their first solid food at a mean age of 13.8 weeks, compared with 8.3 weeks for the 33 bottle-fed infants. Most (38) mothers weaned because they though their babies were hungry (crying after a feed or demanding more frequent feeds, or both). The age of weaning did not influence weight gain, growth in length, or change in skinfold thicknesses. The results suggest that the "4-month rule" for weaning is unrealistic. The decision to wean should be based more on the mother''s interpretation of her baby''s needs than on age alone.     

A longitudinal study of infant faecal microbiota during weaning

For infants, the introduction of food other than breast milk is a high risk period due to diarrheal diseases, and may be corroborated with a shift in the faecal microbiota. This longitudinal study was the first undertaken to understand the effect of the supplementation on the infant's faecal microbiota and particularly the bifidobacteria. Eleven infants were enrolled. Their faecal microbiota were analysed using temporal temperature gradient gel electrophoresis (TTGE) with bacterial and bifidobacterial primers. In parallel, bifidobacterial counts were followed using competitive PCR. Three periods were distinguished: exclusive breastfeeding (Bf period), weaning (i.e. formula-milk addition, W period) and postweaning (i.e. breastfeeding cessation, Pw period). The bifidobacterial counts were not modified, reaching 10.5 (Log10 cells g(-1) wet weight). In the TTGE profiles, the main identified bands corresponded to Escherichia coli, Ruminococcus sp. and Bifidobacterium sp., more precisely Bifidobacterium longum, Bifidobacterium infantis and Bifidobacterium breve. For both TTGE profiles, the analysis of the distance suggested a maturation of the faecal microbiota but no correlation could be established with the diet. Despite a high interindividual variability, composition of the faecal microbiota appeared more homogenous after weaning and this point may be correlated with the cessation of breastfeeding.     

Incubation pattern and foraging effort in the female Water Pipit Anthus spinoletta

Incubation and foraging patterns of female Water Pipits Anthus spinoletta were studied in two breeding seasons in an Alpine valley of Switzerland. Decreased temperature reduced the length of periods spent off the nest (inattentive period), while decreased food availability led to a reduction in time spent incubating (attentiveness), shorter periods spent on the nest (attentive period), more frequent inattentive periods and higher foraging effort, measured as the product of frequency of inattentive periods and twice the flight distance to foraging sites. The negative relation between food availability and foraging effort resulted from more frequent foraging bouts and longer flight distances under poor food conditions. Feeding of the incubating female by the male did not affect foraging effort and attentiveness but did change the temporal pattern of inattentive periods from a few long to several short inattentive periods.     

Primate milk: proximate mechanisms and ultimate perspectives

To understand the evolutionary forces that have shaped primate lactation strategies, it is important to understand the proximate mechanisms of milk synthesis and their ecological and phylogenetic contexts. The lactation strategy of a species has four interrelated dimensions: the frequency and duration of nursing bouts, the period of lactation until weaning, the number and sex ratio of infants that a mother rears simultaneously, and the composition and yield of the milk that mothers synthesize. Milk synthesis, arguably the most physiologically costly component of rearing infants, remains the least studied. Energy transfer becomes energetically less efficient, transitioning from placental support to milk synthesis just as the energy requirements for infant growth, development, and behavioral activity substantially increase. Here we review primate lactation biology and milk synthesis, integrating studies from anthropology, biology, nutrition, animal science, immunology, and biochemistry, to identify the derived and ancestral features of primate milks and enhance our understanding of primate life history.     

The development of intersucking in dairy calves around weaning

Intersucking, i.e. sub-adult or adult cattle sucking at the udder of herd-members, is a problem often reported in dairy herds that leads to udder health problems. The causes of intersucking are virtually unknown, and until now all available countermeasures treat only the symptoms of this behavioural problem. We examined (I) whether intersucking occurs prior to weaning and continues thereafter, and (II) whether its establishment is related to the feeding management during weaning. On 10 dairy farms, we observed the sucking and feeding behaviour of a group of dairy calves (2-5 animals per farm, 38 in total) 1 week before and 1, 5 and 9 weeks after weaning. Calves were weaned off milk at an average age of 21 weeks (S.D. 4.7). We analysed the calves' food rations in order to estimate the adequacy of their energy density. Thirty-five (92%) of the 38 calves performed intersucking already before weaning, with the frequency being highly variable between individual calves (x(med)=5.0 bouts/day, range 0-24.7). Calves with a high intersucking activity before weaning were likely to continue intersucking after weaning (P<0.05). Before and after weaning intersucking could be observed at nearly every time of the day, but was most frequent around feeding. Calves with a long feeding duration (x(med)=260min, range 186-374) showed less frequent intersucking 1 week after weaning (P<0.05). In addition, the frequency of intersucking increased with decreasing adequacy of their rations energy density (r=-0.88, P<0.01), and the highest intersucking activity was recorded on farms with restricted availability of food. The results indicate that intersucking occurs already before weaning, and its establishment may be prevented by a ration and a feeding management that ensures an optimal transition from pre-ruminants to ruminants.     

Pup growth in the fur seals Arctocephalus tropicalis and A. gazella on Marion Island

Subantarctic fur seal Arctocephalus tropicalis and Antarctic fur seal A. gazella pups at Marion Island were weighed frequently until weaning, which occurs earlier in A. gazella (112 days) than in A. tropicalis (± 300 days). The mean birth weight of both species was the same (4·2 kg) and males grew faster than females. Arctocephalus gazella growth was linear to weaning and faster than A. tropicalis growth, which was linear to 120 days of age, slowing until 203 days of age, and thereafter losing weight but recovering perceptibly prior to weaning. Tagging had no apparent effect on pup growth. Faster growth in males than in females is part of the differential growth patterns which lead to adult sexual dimorphism. Arctocephalus gazella pup growth at Marion Island is faster than at South Georgia, indicating that conditions at this, their most northerly breeding locality, are not limiting for pup growth. The decrease in A. tropicalis pup body weight in July/August may result from either a scarcity of food in winter or weaning having been initiated. The two groups (polar and non-polar) of fur seals exhibit two strategies, which include differences in pup growth and suckling period; the polar species have a short suckling period and rapid pup growth and are predominantly pelagic over winter, while the more temperate species have a longer suckling period and slower pup growth and are less pelagic over winter.     

Coprophagy in young laboratory rat

Coprophagy (ingestion of maternal faeces) was found in young laboratory rats between the ages of 16 and 28 days. The degree of this activity during the given period was not constant; a multiple increase on about the 25th day was followed by an abrupt drop and complete cessation coincided with the time of spontaneous weaning. Coprophagy did not appear in prematurely weaned young (at 16 days) which were given faeces and was protracted in undernourished young whose weaning time was prolonged. Young weaned rats without having ingested maternal faeces displayed relative hyperphagy for solid food. This early hyperphagy had later consequences for the feeding behaviour of adult males, which looked for food and consumed it more intensively in a new environment and also hoarded it. Defensive behaviour was not affected.     

Behavioral changes during weaning in captive chimpanzees

Behavioral changes during weaning of chimpanzee infants in captive social groups were compared with those of infants in the natural habitat. Results of the weaning process were the same for the mother-infant pairs in captivity and the natural habitat, i.e., an infant independent of suckling, regular maternal transport and sleeping with the mother. The captive infants, however, did not respond to weaning with depression or regression to infantile behaviors as did infants in the natural habitat. Quite probably the social and physical environmental differences between the two habitats faciliated a less stressful weaning period for the captive mother-infant pairs.     

Comparison of Development and Life History in Pan and Cebus

We examined growth and development in capuchins and chimpanzees in relation to weaning, onset of reproduction, and reproductive life span. Striking differences are evident in neurobehavioral status at birth (more mature in capuchins), the relative duration of infancy (longer in chimpanzees), and the proportional weight of the infant at the time of weaning (greater in capuchins). Although capuchins and chimpanzees spend a similar proportion of life in a weaned but reproductively immature state, chimpanzees spend so much more of their lives as nursing infants that reproductive output per individual is much lower than in capuchins. Discussion centers around tolerated transfers of food (food-sharing) as a potential adaptation to limited foraging success by immature foragers. Perhaps food transfers from adult to infant, which is a more prominent feature of behavior in chimpanzees than in capuchins in natural environments, allow a very small weanling chimpanzee to survive.     

Allonursing in tufted capuchin monkeys (Cebus nigritus): milk or pacifier?

Allonursing, the behaviour of females nursing offspring that are not their own, is relatively frequent in capuchin monkeys. Using focal-animal sampling and ad libitum observations we describe the pattern of allonursing in a wild group of tufted capuchins, Cebus nigritus (4 cohorts, 22 infants), at Iguazú National Park, north-eastern Argentina, and test several hypotheses on the adaptive value of allonursing. During 2,351 contact hours with the group (including 4,207 focal-animal samples totalizing 329 h focused on infants) we observed 39 allonursing bouts. Infants were not allonursed more frequently by close kin than by more distant allomothers. Offspring of dominant females were allonursed more frequently than those of low-ranking females. Nursing bouts were longer than allonursing bouts. Our results suggest that allonursing in tufted capuchins has a social function and is not mainly aimed at providing milk to infants.     

Diurnal rhythms of hepatic carbohydrate metabolism during development of the rat

The ;8+16' feeding schedule (8h feeding and 16h without food in each 24h cycle) was applied to nursing mother rats to study enzyme development in neonatal rats in the absence of solid food. A ;16+8' suckling schedule (16h with the mother and 8h while the mother is fed in a separate cage) was used to show that the increases in pyruvate kinase, glucokinase and aldolase B activities that occur in the late suckling period of liver development do not require the intake of solid food at this time. Their activities may, however, be modulated by the composition of the diet at the time of weaning. Adaptation to the composition of the diet can occur within one feeding period, and to the periodicity of food provision in one or two feeding periods. In the early neonatal period, diurnal rhythms of tyrosine aminotransferase, liver glycogen and glucokinase are either greatly suppressed or absent, but develop rapidly after weaning. Food-dependent rhythms of glycogen and tyrosine aminotransferase were included in the late suckling period (day 14).     

Periodization of the early postnatal development in the rat with particular attention to the weaning period

The early postnatal period is characterized by a great plasticity with critical windows in which any inadequate insult or intervention may be able to influence both positively and adversely postnatal growth and development. After birth the rat littermates enter the presuckling period (initial 6 hours terminated by the first nursing), characterized by transition from the amniotic fluid to the air, by the changes of the ambient temperature, by the termination of placental nutrition and by oxidative stress. After this stage the suckling period initiates and the littermates start to consume milk of their mothers. Comsumption of milk culminates on day 15, then decreases and terminates on postnatal day 28. The end of the suckling period and the onset of physiological weaning is determined by the moment when the youngs for the first time consume the solid food together with milk (postnatal day 17 in rats). On day 19 the first intake of drinking water occurs. The weaning period terminates by the last consumption of maternal milk - on postnatal day 28. It is necessary to stress that the duration of early postnatal periods is independent of the changes of body weight. The precise knowledge of individual ontogenetic periods critical for further development is crucial for the prediction and explanation of reactions to various pathogenetic stimuli both under experimental conditions and in clinical medicine.     

Maternal behavior and early development of pampas deer (Ozotoceros bezoarticus) fawns in a semi-captive environment

Maternal–infant interaction and behaviors are adapted to reduce the risk of predation and increase the probability of survival of the species. We determined how mother–young encounters and communication change by the development of the fawn (locomotion and feeding) throughout lactation in pampas deer (Ozotocerus bezoarticus). We registered the behavior of mother–fawn dyads for the first 60 postnatal days. Our results revealed three main developmental stages in the fawn, hiding (~0–19 days), active (~20–39 days), and adult-like (~40–60 days). In the hiding stage, the fawn stayed hidden, closer to the mother, and spent less time active, the mothers vocalized more often than the fawn, licked the fawns intensively while nursing, and were responsible for initiating nursing. In the active stage, licking behavior and vocalizations of the mother decreased while the fawns ate solid food, initiated nursing bouts, and displayed bursts of running activity. Finally, in the adult-like stage, the fawn showed many signs of nutritional weaning, and similar patterns of activity to their mothers. However, the duration and frequency of nursing bouts were unchanged during the study. We described mother–fawn interaction in pampas deer for the first time, and found that increased running activity in fawns anticipates nutritional weaning. Our results also suggest that to adapt to the development of the fawn, mothers only modify the dynamics of interaction and encounters rather than the time invested in nursing, an activity that also plays a role in maintaining mother–young affiliation.     

Growth rates of Antarctic fur seal Arctocephalus gazella pups at South Georgia

Large numbers of pups of the Antarctic fur seal were weighed at regular intervals through their rearing period in six seasons between 1972 and 1981 at South Georgia. Growth rates and birth and weaning weights were estimated from linear regressions of mean weight on mean age. Female pups had significantly lower growth rates and weaning weights than males, but higher variances for all growth parameters. This may reflect the importance to males of polygynous species of attaining high body weight. Except for an inverse relation between growth rate and birth weight there were no systematic relationships between growth parameters. Seasonal differences in growth rates were substantial and there was no indication that the continuing rapid population increase was affecting pup growth rates. The use of these data in detecting seasonal variations in local food availability is discussed. Preliminary estimates of the energy costs of pup rearing indicate that pup existence metabolism consumes c. 80% and mass gain to weaning only c. 15% of the energy provided by the female.     

Factors affecting weaning weight in Antarctic fur seals Arctocephalus gazella at South Georgia

Summary Relationships between size, body condition, age and feeding-attendance patterns during pup rearing of female Antacrtic fur seals Arctocephalus gazella and their effects on the timing of birth and weaning, pup weight, growth and condition were studied at South Georgia in 1981–1982. Twenty-seven (6 male, 21 female) mother-pup pairs were followed from birth to weaning. The analysis of maternal effects was limited to female pups because of the small sample size of male weaners. High weaning weight was associated with those female pups whose mothers spent more time ashore attending their offspring. Weaning weight showed no relationship with perinatal duration, number of feeding trips to sea, days at sea or date of weaning. A further 63 mother-pup pairs were analysed for the effects of maternal body condition (weight/length), age and timing of birth on offspring body weight and condition. Pup weight and condition were weakly correlated with maternal age in female pups. Male pups born earlier in the season were heavier and in better condition. Maternal and offspring body weight and condition were unrelated. For the Antarctic fur seal population at South Georgia where the food supply was apparently not limiting in summer, maternal condition and foraging time were subordinate to maternal care on land (as expressed by attendance duration) in determining offspring weight at weaning.     

Protein malnutrition of the lactating female rat: effect on maternal behaviour and spontaneous weaning of young rats

Female rats were kept on a diet with a low content of animal protein (5.5%) beginning from the 2nd day after delivery. Beginning from the 10th day after delivery their body weight was persistently lower than that of control females. Also the body weight of their young was lower than that of control animals throughout the experiment, with significant differences appearing on the 17th day of life. Spontaneous termination of maternal milk intake occurred in malnourished young 10 days later than in the controls. Retention of 85Sr in malnourished females was in keeping with their milk production. Irrespective of the differences in body weight and the quality of solid food, the malnourished young began consuming solid food at the same age and in the same relative amounts as the controls. Thus in malnourished young the period of gradual weaning was prolonged by more than to 3 weeks in contrast to 2 weeks in the controls. This is probably due to the slower extinction of the oral sucking mechanism resulting from changes in the maturation of the CNS. No changes were found in maternal behaviour (nest building and efficiency of retrieving) in malnourished females during the suckling period. However, infanticide appeared in some females during the weaning period.     

Is there a link between cot death and child abuse?

Forty five babies delivered in Oxford obstetric units who subsequently died unexpectedly in infancy were compared with 134 controls matched for maternal age, social class, parity, and year of birth to see whether five factors identified in an earlier study as predictive of subsequent child abuse would also predict the sudden infant death syndrome. Epidemiological findings had suggested certain similarities between the two events. In contrast with babies who were abused, four of the five factors did not distinguish between babies who died suddenly and unexpectedly and their controls, but there was a slight increase in the proportion of mothers of babies who died suddenly and unexpectedly for whom nursing staff thought that support and advice on feeding the baby were needed. Factors predictive of child abuse did not predict sudden infant death in this study.     

Kin Recognition and Maternal Care under Restricted Feeding in House Mice (Mus domesticus)

This study tests the hypothesis that female house mice (F1 generation of wild caught Mus domesticus) should preferentially invest in own offspring if confronted with young of different degrees of relatedness. The maternal behaviour of females with litters of 4 own and 4 unrelated alien young (cross-fostered at day 1 of lactation) was analysed during a lactation period of 22 days both under ad libitum and under restricted feeding (food was restricted by 20%). Cross-fostering and restricted feeding had no effect on the amount of time spent nursing until weaning. Under both feeding conditions the females did not differ in their maternal behaviour towards own and alien young: there were no significant differences either in the amount of time spent nursing own versus alien pups or in the time spent licking own versus alien young. Weight gain of own and alien = wild littermates did not differ significantly in mixed litters and was similar both under ad libitum and under restricted feeding. Such indiscriminate behaviour might be adaptive if female house mice prefer to communally nest with a relative and thus improve their inclusive fitness by investing in own and related offspring in a communal nest. Under moderate restricted feeding females could not wean the entire litter but reduced litter size by cannibalizing on average 2.7 pups (75% of the pups were killed when they were 4–8 days old). Females with cross-fostered litters killed as many own as alien young. This suggests that females cannot discriminate between own and unrelated young if cross-fostering takes place at day 1 of lactation. Besides testing kin recognition abilities, the experiments also allow analysis of the weaning strategy of females under food shortage. Under restricted feeding, body weight of the females was significantly lower during middle lactation than under ad libitum feeding. Weaning weight of young in reduced litters under food restriction (9–10 g) did not differ significantly from weaning weight of young in litters of 7–10 young, but was lower than that of young in similar sized litters (litter size 6), under ad libitum feeding. The maternal behaviour of cannibalizing some young under food shortage can be interpreted as a weaning strategy which results in the largest number of offspring that can be raised to a minimal weaning weight of 9–10 g. Such a weaning strategy might represent a favourable trade-off between number and size of young produced.     

Nursing behavior in dam-reared Russian saiga (Saiga tatarica tatarica) at the San Diego wild animal park

This study was designed to examine the nursing patterns and related behavior of young saiga raised by their dams. Four captive born lambs were observed at weekly intervals during continuous 14 h watches for the first 7 weeks of life. One-week-old lambs were found to nurse at an average rate of 1.1 bouts per hour and nursed for an average of 14.6 seconds per bout. This high nursing frequency and the average total daily nursing time of 242 seconds decreased rapidly with age. Saiga lambs sampled solid food as early as 4 days of age and were nearly dependent on solid food by the age of 7 weeks. Communal nursing, in which one or more lambs would nurse from an unrelated adult female while she nursed her own, was common. Grooming of the lamb by the dam was never seen except immediately following birth. © 1994 Wiley-Liss, Inc.