Authors
1
Assistant Professor, Department of Animal Science, Faculty of Agriculture and natural resource, University of Gonbad kavoos, Gonbad kavoos, Islamic Republic of Iran.
2
Professor, Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Islamic Republic of Iran
3
Associate Professor, Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Islamic Republic of Iran
4
Associate Professor, Department of Animal Science, Agriculture and Natural Resources Research Center, Shahrekord, Islamic Republic of Iran.
Abstract
Information about mortality of 6426 lambs which were born from 223 rams and 1769 ewes from years 1991 to 2015 in Sarakhs’ Karakul sheep breeding station was used. The trait under study was lambs’ monthly cumulative survival rate from time of birth to one year of age. Frequency of mortality causes and survival distribution function were analyzed using Freq and Lifetest procedures of the SAS statistical software, respectively. The overall lambs' mortality from birth to yearling age was 14.57 percent. The most important mortality reasons were starvation, digestive and respiratory illnesses. The lambs’ cumulative survival rate was 85.4 percent in their first year of life. Regression coefficient of survival from lamb age showed that lamb's survival decreased 0.037% per day. Lambs’ mortality rates were 7.8, 4.06, 1.23 and 1.48 percent in the first, second, third and fourth triplet months of lambs’ life, respectively. The lambs’ highest mortality occurred in 1st, 2nd, 6th and 10th month of age. As mortality rate was highest in the first 3 months of lambs' life, it is suggested to apply better care and nutritional management for the ewes and lambs in this period to increase survival rate of lambs.
Keywords