The relationship between ewe post-natal behaviours and other ewe and lamb traits
Ewe MBS has been reported to be related to lamb neonatal progression, particularly to the time it takes for the lamb to reach the udder and begin to suck (Parker and Nicol 1993). Lambs born to ewes with a greater MBS progress more quickly through early neonatal behaviours than those whose dams have a low MBS. Parker and Nicol (1993) showed that lambs born to ewes with a MBS of four and five located the udder in 30% less time than lambs born to ewes with a MBS of three. In addition Corner et al. (2010) showed that ewe MBS was negatively correlated with the latency of the lamb to make contact with its dam (Table 1.8). Murphy et al. (1994) reported a negative correlation between the total time the ewe spent licking her lambs and her box test score. There was, however, a positive correlation between MBS and the score from the
‘box test’ (Murphy et al. 1994). Similar results were reported by Plush et al. (2011) where MBS was also positively correlated with the score from the ‘box test’.
The MBS was designed by O’Conner et al (1985) to be determined at 24-48 hours after birth, however in the studies by Parker and Nicol (1993), Corner et al. (2010) and Plush et al. (2011) MBS was recorded around 12-24 hours. Disturbing the ewe and her lambs too close to birth could jeopardize the formation of the ewe-lamb bond (Fisher and Mellor 2002). However, in the study by Murphy et al. (1994) MBS was recorded immediately after birth. Nevertheless, the temperament of the ewe and her MBS, regardless if recorded immediately after birth or at 24 hours, appear to be related (Parker and Nicol 1993; Murphy et al. 1994; Corner et al. 2010; Plush et al. 2011).
Table 1.8. Correlations of post-tagging ewe and lamb behaviours (from Corner et al. 2010). 1. Ewe weight 2. Lamb birth weight 3. Ewe MBS 4. High bleats 5. Low bleats 6. Lamb bleats 7. Time to bleat 8. Time to stand 9 .Time to contact 10. Time to suck 11. Time to move 12. Time to follow 1. Ewe weight (P130) - 0.17** -0.19** -0.20** -0.20** -0.21*
2. Lamb birth weight 267 - -0.16+
3. Ewe MBS 265 265 - -0.29*** -0.36***
4. Ewe high bleats 266 266 265 - 0.16** 0.58*** 0.20* -0.13*
5. Ewe low bleats 267 267 265 266 - 0.29**
6. Lamb bleats 263 263 261 262 263 - -0.14* -0.12+ 0.15*
7. Lamb time to bleat 239 239 237 238 239 235 - 0.56*** 0.19** 0.24* 0.25* 0.16*
8. Lamb time to stand 240 240 238 239 240 236 222 - 0.40*** 0.21* 0.31** 0.16*
9 .Lamb time to contact 238 238 236 237 238 234 219 222 - 0.32** 0.20*
10. Lamb time to suck 89 89 89 89 89 89 84 89 88 - 0.27*
11. Lamb time to move 108 108 107 108 108 106 98 106 104 28 -
12. Lamb time to follow 267 105 265 266 267 263 239 240 238 89 108 -
MBS= maternal behaviour score.
Correlation coefficients and P-values are presented above the diagonal and number of animals included below. Blank cells indicate non-significant correlations (P>0.1); +P<0.1, *P<0.05, **P<0.001 and ***P<0.0001.
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O’Connor et al. (1996) reported that there was a positive correlation between the frequency of ewe bleats and ewe MBS over a 14 week period between birth and weaning. Murphy et al. (1994) reported a weak negative relationship between ewe maternal behaviour and the number of high-pitched bleats emitted by the ewe. A negative correlation between ewe MBS and the number of ewe high-pitched bleats at tagging were reported by Everett-Hincks et al. (2005a; 2007). Further a positive correlation between ewe MBS and ewe low-pitched bleats was reported by Everett- Hincks et al. (2007). Corner et al. (2010) reported that the MBS of the ewe was negatively correlated with the number of ewe high-pitched distress bleats that were emitted by the ewe. Ewe high-pitched bleats were also negatively correlated with the time required for the lamb to follow its mother (Corner et al. 2010). They further found that the number of ewe high-pitched bleats was positively correlated with: the number of total lamb bleats, the time required for the lamb to make contact with ewe and the time to suck from the dam.
The ewe’s grooming behaviour and reaction to sucking attempts appear to be related to vocalisation of the newborn lamb (Dwyer et al. 1999). As previously mentioned, lamb vocalisation has been suggested to indicate the need of the lamb, and may thus elicit increased maternal attention (Dwyer et al. 1999). Conversely, Dwyer (1999) stated that the number of low-pitched bleats emitted by the ewe is correlated
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are more stimulating to their mothers. The dam will thus respond with increased maternal care and stimuli, each stimulus reinforcing the ability of the ewe and the lamb to recognise each other.
It has further been suggested that a vigorous lamb is better at discriminating its dam from an alien ewe and reaches her more quickly during a pen test than a less vigorous lamb (Nowak et al. 1989). Nowak et al. (1997) found that lambs that were prevented from sucking during the first six hours after birth were significantly worse in discriminating their dams during a separation test, when compared to lambs that had free access to suck. A vigorous lamb is likely to have had more opportunity to suck and interact with the ewe, and hence have learnt the mother’s features better than a non- vigorous lamb (Nowak et al. 1997).
Lamb neo-natal behaviours with lamb traits
Many neonatal behaviours expressed at 12 to 24 hours after birth are inter- related (Corner et al. 2010; Dodd et al. 2012). Corner et al. (2010; Table 1.8) showed that the number of lamb bleats was negatively correlated with the latency of the lamb to bleat at 12 to 24 hours after birth. The time it took for the lambs to bleat was found to be positively correlated with: time to stand, make contact, suck, move and follow their dam at 12 to 24 hours after birth (Corner et al. 2010). Corner et al. (2010) also reported a positive relationship between the latency for the lamb to make contact with the dam and latency to suck and move, also at 12 to 24 hours after birth.
Nowak (1990) showed a positive correlation between the number of lamb bleats emitted at birth and the time it subsequently spent with its dam during a triangle test at 12 hours. This indicate that lambs that showed higher bleating at birth were more likely to successfully discriminate their mothers from alien ewes, compared with those that have low bleating rates (Nowak 1990).
Even though a number of studies report on behavioural correlations many inconsistencies exist. A possible reason for these inconsistencies may be the breed of sheep, the external environment and the timing of the behavioural observations in relation to birth.
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