Diurnal distribution of lambing in sheep and its relation with behaviour and survival of the neonate lamb

Abstract

A total of 348 Finnish Landrace – Rahmani crossbred ewes were used in this study to show the diurnal distribution of lambing and its relation with behaviour and survival of the neonate lamb. At birth, based on lambing distribution at twelve-hour periods, ewes were allotted into either day light time group which included ewes that lambed during the day light hours (from 6.00 am to 6.00 pm) or night time group which included ewes that lambed during night hours (from 6.00 pm to 6.00 am). Data recorded included time of birth, neonatal behavioural progress, body temperature of neonatal lambs over the first 3 days of life and lamb mortality rates from birth to weaning. Significantly more ewes lambed during the night time than throughout the day light hours. Neither litter size nor birth weight of lambs had a significant effect on time of parturition. However, ewe parity had a significant effect on lambing time. With respect to neonate lambs, night time born lambs were less active at birth and denoted a decrease in their body temperature over the first 3 days of life with higher mortality rates from birth until weaning specifically during the first week of birth compared to day light born lambs. It could be concluded that, more lambing occurred during the night time than during the day light time. Litter size and birth weight of lambs did not appear to affect the time of parturition, whereas significant differences in lambing time were observed with regard to parity. Moreover, exposure to cold disrupted the behavioural patterns of the neonate lambs, decreased their ability to maintain body temperatures and increased mortality rates.