Suckling behavior in captive plains zebra (Equus burchellii): Sex differences in foal behavior1

Abstract

We predicted that the proportion of suckling attempts rejected and terminated by the mother would be greater for female foals than male foals, based on parent offspring conflict theory and on the assumption that throughout the study, all zebra mothers were in good condition because of captivity. We presumed that an increasing rate of suckling terminated or rejected by a mother would indicate a decreasing effort by the mother to invest in her offspring. We observed foals of captive plains zebras at the Dvůr Králové Zoo, Czech Republic. We found that the probability of successful suckling tended (slope = 0.0016; Z = 1.78; P = 0.074) to increase with increasing age of the female foals, but decreased (slope = -0.0018; Z = -2.51; P = 0.012) with increasing age of the male foals. The proportion of suckling bouts terminated by the mother decreased (slope = -0.0077; Z = -4.27; P < 0.0001) with increasing age of the female foals, but not the male foals (slope = -0.0005; Z = -0.34; P = 0.732). Our results indicate that conflict between mothers and female foals was less than that between mothers and male foals. The observed sex differences in termination and rejection of suckling bouts could be explained by the different behavior of the male and female foals, or by the selective maternal investment. Finally, we revealed no significant effect of herdmates on suckling behavior.

Further evidence for sex differences in suckling behaviour of captive plains zebra foals

“…We have previously found evidence of sex differences in rejection and termination of suckling bouts in captive plains zebras (Equus burchellii, Pluháček et al 2010a). We found that the probability of successful suckling tended to increase with increasing age of female foals but decreased with increasing age of male foals and that the proportion of suckling bouts terminated by the mother decreased with increasing age of female foals, but not male foals (Pluháček et al 2010a). In the present study, we performed further analyses showing other sex differences in suckling behaviour and supporting one of the hypotheses.…”

“…1 The length of interruption within suckling bouts in captive plains zebra a according to the initiator of interruption and b according to the sex of the foal. The values are adjusted means±SE with our previous findings, showing that with increasing age of the foal, the mother rejected suckling attempts and terminated suckling bouts more often in male foals than in female foals (Pluháček et al 2010a).…”

“…In the first season (1999/2000), the herds contained six, five and four breeding mares, and in the second season (2001/ 2002), they contained two, five and four breeding mares, respectively. For details of herd observations and housing, see Pluháček et al (2007Pluháček et al ( , 2010a. In total, the three herds were observed for 315, 318 and 198 h, respectively.…”

Strategy of goitered gazelle suckling behavior

“…In these cases, however, it was not made clear why suckles were not recorded and calculated as they were demonstrated naturally by the animal-taking into account all intervals-instead of producing artificial rules for recording this behavior. Fifth, many authors (Shackleton and Haywood 1985;Gauthier and Barrette 1985;Habibi 1987;Lavigueur and Barrette 1992;Cameron et al 1999;Mauget and Mauget 2009;Pluhacek et al 2010Pluhacek et al , 2014 make the assumption that suckles shorter than 5 s are not really suckling, but rather unsuccessful attempts to suckle, while other researchers define different thresholds for nutritive suckles: 3 s for Oryx dammah (Drews 1991) and 8 s for Ovis canadensis (Festa-Bianchet 1988a, b). Certainly, offspring do not typically receive milk at the moment they begin suckling, but a 5-s interval (3 or 8 s in other versions) has not been determined to be a real threshold for milk transfer and is actually an arbitrary cutoff.…”

Concurrent Lactation and Pregnancy: Pregnant Domestic Horse Mares Do Not Increase Mother-Offspring Conflict during Intensive Lactation

“…Although suckling behaviour was not found a reliable indicator of milk or energy intake [16], even in foals [17], it can be considered as the behavioural measure associated with parent-offspring conflict over maternal resources [16], [17] and as the measure of the level of maternal care provided by the mother in contrast with foal's needs [10], [18], [19]. Termination of suckling seems to be of great importance.…”