Suckling behavior of ewes in early lactation

Previous studies have described the basic suckling behavior of ewe/lamb pairs during daylight hours, but no information is available for the hours of darkness. In this study, the natural pattern of suckling was recorded over a 24-h period once a week for the first 7 weeks of lactation in 7 free-ranging Merino ewes with single lambs. Both the mean suckling frequency per 24 hours and the mean duration of individual suckling bouts declined with increasing age of the lamb. Suckling frequencies fell from 36 +/- 5.5 sucks/24 h at 1-2 weeks of age to 14.3 +/- 2.78 sucks/24 h at 6-7 weeks of age. Individual suckling bout duration fell from 41.1 +/- 9.9 s at 1-2 weeks of age to 11.9 +/- 1.2 s by 6-7 weeks. Suckling frequencies per hour were significantly greater during daylight as compared to darkness (p less than 0.05). We suggest that the declining frequency and duration of suckling bouts with age probably accounts for the waning influence of lactation on the reproductive state of the ewe, and that the maintenance of a critical interbout interval may first break down at night.