Abstract:
The study was conducted with the aim of performance evaluation and developing live
weight prediction equation for Gumuz sheep under on-station management. The data
collected at Metema Gumuz sheep station from 2016 to 2021 was used to evaluate
growth, reproductive performance, survival rate and to develop prediction equations
from linear measurements for Gumuz sheep. A general linear model (GLM) procedure
of the Statistical Analysis System (SAS, version, 9.4) was used to analyzed growth,
reproductive performance and linear body measurements. Survival rate was analyzed
using GENMOD procedure of SAS with logit link function and the live weight
prediction equations were developed using stepwise regression procedure of SAS. The
overall least squares mean for birth (BW), one-month (OMW), three-month (WMW),
six-month (SMW), nine-month (NMW) and yearling weight (YW) of Gumuz sheep were
2.40±0.04, 5.80±0.10, 9.29±0.21, 13.33±0.38, 15.62±0.50, and 18.40±0.62kg,
respectively. Sex, dam parity, ewe postpartum weight, birth type, season, and year of
birth were sources of variation that affect lamb growth performance at various stages.
The overall least-squares means of body weight gain from birth to one month, one month to three-month, three-month to nine-month, nine-month to twelve-month and
birth to yearling were 100.50±3.33,75.78±2.05, 48.02±1.6, 40.72±1.32, 39.63±1.53,
and 42.22±1.72 g/day, respectively. The average age at first service and lambing of
Gumuz sheep were 293.94±20.34 and 442.02±21.20 days, respectively. Birth year, ewe
postpartum weight, and dam parity were important factors that affected age at first
service and lambing. The mean lambing interval (LI) for Gumuz sheep was
289.59±10.92 days whereas; liter size (LS) and annual reproductive rate (ARR) were
1.21±0.03, and 1.59±0.11, respectively. The least-squares mean of survival rate from
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birth to one, one to three, three to six, six to nine, nine to twelve and birth twelve
months of ages were 87.11± 0.41, 79.81±0.35, 74.78±0.32, 68.78±0.34 and
54.85±0.32%, respectively. Season of birth, year of birth, birth type, lamb's birth
weight, and dam parity had a considerable influence on the survival rate of lambs. Age
was a highly significant (P<0.001) source of variation for all body measurements while
sex significantly affected (P<0.01) some traits (WH, FCL, and HL) only. Most body
measurements were positively and highly (P<0.001) correlated with body weight. The
stepwise multiple regression analysis revealed that HG and BL were the utmost
important variables to predict live body weight for one month male and female,
respectively; BL and WH were important variables to predict live body weight for
three-month male and female, respectively; PH was important variables to predict live
body weight for six-month male and female, WH was an important predictors for nine month male and female, HG were important predictors for yearling male and female
lambs. Thus, where there is no access to weighing balance and in the field, the
producers could use these traits to predict live weight. To improve the growth
performance and survival rate of lambs, better management should be given especially
for lambs born in dry season, twin birth and for those lambs born with light weight