Angélica Terrazas

Learning of olfactory cues is not necessary for early lamb recognition by the mother

Ewes identify their young through the use of different sensory modalities. Olfactory recognition, which mediates selective acceptance at the udder, is established at 4 h postpartum (pp). Visual and auditory cues are involved in recognition at a distance, which is evident at 12 h pp. This study investigates whether anosmic ewes are able (a) to develop visual and auditory recognition and (b) to restore selective acceptance of their lamb at the udder. Visual and auditory recognition was assessed in anosmic and intact ewes at 12 h and 24 h pp by a test of two choices: their own and an alien lamb. Selectivity at allowing suckling was tested by presenting successively an alien and the familiar lamb at 4 h, 3 days, and 1 month pp. In the two-choice recognition test, at both 12 h and 24 h pp, anosmic as well as intact ewes showed a preference for their familiar lamb. Although anosmic ewes showed no difference in their acceptance of alien and familiar lambs for suckling at 4 h and 3 days pp, they nursed the alien lamb less at 1 month pp and showed more rejection behaviors toward it. Thus, visual, auditory, or both those types of recognition can be rapidly established, independent of olfactory recognition. Moreover, differential behavior of anosmic ewes toward their own versus an alien lamb at the udder at 1 month suggests that vision and audition may compensate to some extent for the loss of olfaction.

Do ewes recognize their lambs within the first day postpartum without the help of olfactory cues

Two studies were carried out to test the ability of Préalpes du Sud x Lacaune (Study 1) and Rambouillet ewes (Study 2) to recognize their lambs during the first 24 h postpartum. Ewes were given the choice between their own and an alien lamb of approximately the same age, in a triangular pen of 10 m×10 m×10 m. A lamb was placed in each of the two corners while the mother was released from the third corner. Direct access to the lambs was prevented by an open barrier located at 1 m from the pens in which the lambs were kept. Ewes were studied at 8 h (n=10, 12), 12 h (n=20, 10) and 24 h postpartum (n=29, 9; Study 1 and Study 2 respectively). Tests lasted 3 and 5 min in Study 1 and 2, respectively. Although the first choice of the ewes did not differ from random, in both studies mothers spent significantly more time near their own lamb than near the alien. In both breeds a significant preference for the own lamb was already present at 8 h (P<0.05). We conclude that ewes are very likely to recognize their lamb without the aid of olfactory cues as early as 8 h postpartum, which is much sooner than thought from previous studies.

Sensory and physiological determinants of maternal behavior in the goat (Capra hircus)

Maternal behavior in the goat appears at the time of parturition, partly under the activating influence of vaginocervical stimulation. Mothers actively lick their neonate and rapidly establish a selective bond with their kid through olfactory recognition. They also develop visual and acoustic recognition of the kid within 4 h following birth. Acoustic recognition is present at 48 h. The establishment of maternal recognition can be impaired by underfeeding during the second half of pregnancy. There is no indication that the mechanisms controlling the onset of maternal behavior and bonding are different from those reported in sheep, despite the fact that lambs start to follow their mother within a few hours after birth and kids hide for about a week. During lactation, the cues provided by the kid are necessary for the maintenance of maternal responsiveness, but suckling itself does not appear of primary importance. The presence of the kid also modulates the hormonal response to udder stimulation and influences recovery of postpartum sexual activity when kidding (i.e. birthing) takes place in autumn. Finally, the rapid establishment of mutual attachment between mother goats (does) and their kids offers the possibility to investigate an aspect of mother-young affiliation that is not present in many laboratory species.

Maternal Olfaction Differentially Modulates Oxytocin and Prolactin Release during Suckling in Goats

In postparturient goats, olfactory recognition of the young allows the establishment of a selective bond between the mother and her kids. Once this bond is formed, the mother rejects alien young that attempt to suckle. We tested whether the development of the maternal selective bond in goats modulates prolactin (PRL) and oxytocin (OT) release in response to suckling. On day 37 of lactation, serial blood samples were taken during nursing of the mothers own or alien kid(s) in 10 intact/selective goats and in 10 goats rendered anosmic/nonselective through prepartum peripheral ZnSO(4) irrigation. Spontaneous nursing behavior was also studied weekly from day 7 to 30 of lactation, at which time milk production was measured. Maternal selectivity had no effect on PRL release, in contrast to OT release, which was significantly affected by this factor. Intact mothers released OT only when nursing their own kids, but not with aliens, while anosmic/nonselective dams showed an increase in OT levels regardless of the identity of the kids. In addition to these effects on maternal selectivity, the amplitude of the response of both hormones was lower in anosmic mothers than in intact mothers. Finally, nursing behavior and milk production were not significantly affected by anosmia. We conclude that maternal selective behavior in goats, which relies on the individual olfactory signature of the kid, modulates the OT, but not the PRL, response to suckling. In addition, perception of the smell of the young appears to have a general facilitatory effect, independent of the kids identity, on the release of both hormones.

Differential effects of undernutrition during pregnancy on the behaviour of does and their kids at parturition and on the establishment of mutual recognition

We investigated whether undernutrition during the second half of pregnancy impaired the behaviour of does and their kids at parturition and early mutual recognition. Twenty-two control and 22 underfed mixed-breed, multiparous dairy goats were used, together with their respective kids (control, n = 31: nine singles, 16 twins and six triplets; underfed, n = 32: 11 singles, 18 twins and three triplets). Undernutrition involved limiting protein and energy intake at 70% of the nutritional requirements for maintenance and foetal growth from day 70 of pregnancy until birth. The behaviour of mothers and their two first-born kids was observed for 90 min from the birth of each kid. Maternal olfactory recognition of the kid was assessed at 4 h post partum by testing selective nursing behaviour. Non-olfactory recognition was assessed at 8 h in a two-choice test excluding olfactory cues. In kids, preference for the mother was assessed in a two-choice test at either 12 or 24 h post partum. Bodyweight of does and kids were lower in the underfed group up to 2 weeks post partum. At parturition, licking, maternal bleating frequency and latency to nursing did not differ between nutritional groups. Control kids were faster than underfed kids to stand, search for and reach the udder, but underfed kids bleated more and tended to spend more time at the udder. Both control and underfed does accepted their own kid and rejected the alien in the selectivity test at 4 h. In contrast, at 8 h post partum, only control goats showed a significant preference for their own kid in the non-olfactory recognition test. Both control and underfed kids showed a preference for their own mother at 12 and 24 h and undernutrition during pregnancy had little influence on the performance of kids. However, 12 h-old underfed kids tended to be less active than control kids and visited their own mothers less than control kids. There were no significant correlations between the behaviour of the mother or of the kid at parturition and their performance in the discrimination tests. Overall, undernutrition in the second half of pregnancy appears to be more detrimental for the behaviour of the mother than for the kid. Furthermore, it has more impact on the establishment of maternal non-olfactory recognition than on maternal care at parturition or the establishment of maternal selectivity.

Cortisol and pain-related behavior in disbudded goat kids with and without cornual nerve block

Plasma cortisol and behavior were measured in disbudded goat kids with and without the use of cornual nerve block. A total of 45 kids were used in 5 experimental groups (n=9, males and females). Group LidoD was infiltrated with 1 mL of 2% lidocaine locally at the cornual branches of lacrimal and infratrochlear nerves, 15 min before thermal disbudding. Group Lido was similarly infiltrated and was not disbudded. In group Sim, the disbudding procedure was simulated. A control group (CD) was disbudded without lidocaine infiltration, and group SD was infiltrated with saline before disbudding. The cornual nerve block did not prevent the short-term increase in cortisol levels during and after disbudding. LidoD, CD and SD groups showed higher cortisol concentrations than Lido and Sim (p<0.05) during the first 20 min after the procedure. Frequency of vocalizations during the procedure was significantly different between groups and was higher in SD (29.6 ± 3.1; mean±SE) and CD (28.4 ± 3.1) than in Sim (16.6 ± 3.1; p<0.05). Infiltrating lidocaine did not decrease this response to disbudding (21.1 ± 3.1; p>0.05). Struggles tended to be higher in SD (16.5 ± 2.5), CD (17.8 ± 2.5) and LidoD (15.6 ± 2.5) than Sim (10.6 ± 2.5; p=0.1). The total behavioral response was different between groups (CD, 59.6 ± 6.8; LidoD, 52 ± 6.8; SD, 62.6 ± 6.8; Sim, 36.8 ± 6.8; p=0.05), and disbudded animals showed the strongest reactions (disbudded, 58.1 ± 3.9 vs non-disbudded, 36.8 ± 6.8; p=0.01). It was concluded that cornual nerve block (lacrimal and infratrochlear) using 2% lidocaine did not prevent pain during thermal disbudding of goat kids.

Preference of 12-h-old kids for their mother goat is impaired by pre-partum-induced anosmia in the mother

We investigated whether kids were able to discriminate their own mother from an alien one in a two-choice test on the day of birth when they had access to acoustic, visual and olfactory cues from their mother, and whether this discrimination depended on the selective maternal behaviour of the mother (i.e. exclusive nursing of own kids). When given the choice between their own mother and an alien equivalent dam, 8-h-old kids did not show a significant preference for their dam, whereas 12- and 24-h-old kids did. When given the choice between their own and an alien mother that were both non-selective because they had been rendered peripherally anosmic by irrigation of the nostrils with zinc sulphate, 12-h-old kids did not show a significant preference for their mother. These results are similar to those reported in sheep and may suggest that the contrast of behaviour between their own and an alien mother existing in normosmic does is important for discrimination of dams by kids at this age. Finally, testing 8-h-old kids in a smaller enclosure resulted in some improvement of their performance, although they still failed to display a significant preference for their mother. On the whole, kids are able to discriminate between their own and an alien mother goat as early as previously reported in lambs. The impairment of this ability when mothers are anosmic and not selective suggests that acceptance behaviours displayed by the mother may serve as one of the cues orientating the choice of the kid when given the choice between intact mothers. Finally, the present results do not suggest the existence of fundamental differences in the establishment of a preference for the mother between lambs, which are followers, and kids, which are hiders.

Behavior of lambs at different ages during brief periods of increased sensorial isolation from their mothers

ABSTRACT To determine the behavior of different‐aged lambs during short periods of increased sensorial isolation from their mothers, 60 ewe‐lamb pairs were randomly assigned to one of the following groups: “C,” intact lambs that remained with their mothers; “A,” lambs with restricted auditory capacity; “A+V,” lambs with restricted auditory and visual capacities; “A+V+W,” lambs with restricted auditory and visual capacities plus separation from their mothers by an open wire mesh; and “A+V+S,” lambs with restricted auditory and visual capacities plus separation from their mothers by a solid wall. These treatments were repeated in the same animals when lambs were 3 (G3), 10 (G10), and 20 (G20) days old. The behavior of lambs was recorded during each 15‐minute separation period, and data were examined using covariance analysis to determine differences for repeated measures over time. In general, after the physical separation from the ewes (A+V+W and A+V+S groups), lambs emitted more vocalizations (3, 10, and 20 days old) and displayed more frequent urination (3 days old), exploration of objects (20 days old) and conspecifics (3 and 20 days old), escape attempts (A+V+W at 10 and 20 days of age; A+V+S at 20 days old), or walking (A+V+W at 10 and 20 days of age; A+V+S at 3, 10 and 20 days old) and lying down (10 and 20 days old for A+V+W and 3 days old for A+V+S) in comparison to the other treatments. G10 and G20 lambs of the A+V, A+V+W, and A+V+S groups also displayed greater values for walking activity (P < 0.05) in comparison with G3 lambs. In general, it is concluded that the exhibition of the examined behavioral parameters was increased with the degree of sensorial isolation, and particularly when the physical contact between the lambs and their dams was restricted. As lambs became older, they showed an increased behavioral reactivity in response to the increased sensorial isolation.