GENETIC EVALUATION OF DECCANI SHEEP
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Date
2017-03-23
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PVNR TVU AND HYDERABAD
Abstract
Present study was conducted on 301 Deccani sheep born to fourteen sires and
189 dams during October, 2012 and July, 2015 at Livestock Research Station,
Mahabubnagar. Data on growth, production and reproduction traits were subjected to
least squares analysis to study the effect of non-genetic factors and genetic parameters
were estimated based on adjusted data.
Body weight at birth and 180 days was significantly influenced by sex at birth;
by season of birth at 90 and 270 days and parity at 30, 45 and 60 days. The overall
least squares mean body weights were 2.72 ± 0.03, 4.37 ± 0.07, 5.90 ± 0.10, 7.49 ±
0.12, 9.03 ± 0.14, 10.32 ± 0.15, 11.48 ± 0.16, 15.58 ± 0.15, 19.09 ± 0.14 and 22.95 ±
0.18 kg at birth, 15, 30, 45, 60, 75, 90, 180, 270 and 360 days of age, respectively.
In general, sex of lamb and season of birth significantly influenced ADG and
Kleiber Ratio. The overall least squares mean ADG1 (0-3m), ADG2 (3-6m) and
ADG3 (0-6m) were 97.22 ± 1.71, 45.28 ± 0.85 and 70.27 ± 1.50 g and KR1 (Kleiber
ratio, 0-3m), KR2 (3-6m) and KR3 (0-6m) were 15.44 ± 0.14, 9.07 ± 0.04 and 15.67 ±
0.08, respectively. Male lambs and those born during season I were heavier and had
higher ADG and KR.
In general, significant influence of sex during certain pre-weaning periods,
season of birth at all ages, ewe weight during all post-weaning ages was observed on
height at withers and rump height. Least squares mean height at withers (HAW) and
rump height (RH) ranged from 39.47 ± 0.38 to 68.90 ± 0.38 and 39.50 ± 0.38 to 67.45
± 0.43 cm from birth to one year of age, respectively.
Body length was significantly influenced by season and ewe weight at 180,
270 and 360 days; by ewe weight and parity at 90 days. Overall least squares mean
body length ranged from 33.87 ± 0.51 to 64.58 ± 0.51 cm from birth to 360 days.
Significant effect of season of birth on heart and paunch girth during postweaning
periods was observed. The least squares mean heart and paunch girth ranged
from 39. 94 ± 0.54 to 72.69 ± 0.48 and 40.62 ± 0.58 to 73.05 ± 0.54 cm from birth to
360 days of age, respectively.
Chest depth was significantly influenced by sex during pre-weaning periods;
by season at birth, 30, 180, 270 and 360 days; by ewe weight at 180, 270 and 360
days and by parity at 75 and 90 days. Mean chest depth from birth to 360 days age
ranged from 19.15 ± 0.35 to 43.55 ± 0.36 cm.
The effect of sex of lamb on chest width at 15, 30, 45, 60, 75, 180, 270 and
360 days age; that of season of birth at 15, 30, 45, 180, 270 and 360 days was
significant. Overall least squares mean chest width from birth to 360 days age ranged
from 6.18 ± 0.19 to 25.09 ± 0.21 cm.
Significant influence of sex on fore-cannon bone length at 0, 15, 30, 45, 60, 75
and 360 days; on hip width at all ages; on thigh circumference at 30, 45 and 60 days;
that of season and ewe weight on fore cannon bone length at 180 days and on thigh
circumference at all post weaning ages studied was observed. The overall least
squares means from birth to 360 days of age ranged from 10.36 ± 0.16 to 27.64 ± 0.19
for fore-cannon bone length; 4.95 ± 0.06 to 17.23 ± 0.09 for hip width and 22.05 ±
0.45 to 43.48 ± 0.33 cm for thigh circumference.
Significant differences among sexes were observed for pre-slaughter weight,
empty body weight, hot carcass weight and weights of edible and inedible organs. The
corresponding means were 21.35 ± 0.43, 17.95 ± 0.23, 10.03 ± 0.17, 0.84 ± 0.02 and
4.89 ± 0.07 kg, respectively. Mean loin eye area was 7.53 ± 0.19 cm2.
The overall mean weights of primal cuts Viz. leg, loin, rack, neck and
shoulder, breast and fore shank were 3.31 ± 0.05, 1.07 ± 0.02, 1.44 ± 0.06, 2.43 ± 0.06
and 1.79 ± 0.02 kg, respectively with a meat content of 2.14 ± 0.03, 0.67 ± 0.01, 0.71
± 0.03, 1.43 ± 0.03 and 1.06 ± 0.01 kg, respectively.
The overall mean lactation milk yield and lactation length were 16943.26 ±
213.06 g and 81.64 ± 0.35 days with significant differences among seasons. The mean
fat and SNF per cent recorded was 3.77 ± 0.06 and 9.97 ± 0.02, respectively.
The least squares mean age at first tupping, weight at first tupping, age at first
lambing, weight at first lambing, gestation period, litter size at birth and litter size at
weaning were 338.59 ± 9.36 days, 21.89 ± 0.50 kg, 644.65 ± 11.59 days, 24.56 ± 0.33
kg, 155.53 ± 0.49 days, 1.00 ± 0.00 and 0.80 ± 0.04 respectively. All the traits were
significantly influenced by season.
The heritability estimates obtained for body weights were low during preweaning
period (0.10 ± 0.01 to 0.14 ± 0.07) and moderate during post-weaning period
(0.20 ± 0.06 to 0.30 ± 0.05). The genetic and phenotypic correlations among body
weights were all positive except that between BW0 and BW360.
The heritability estimates at different ages were very low for height at withers,
heart girth and paunch girth (0.01 ± 0.00 to 0.19 ± 0.03) while the estimates were low
to moderate for body length and chest depth (0.06 ± 0.00 to 0.33 ± 0.04).
The genetic and phenotypic correlations of different biometrical measurements
at different age periods were positive and ranged from 0.15 ± 0.04 to 0.99 ± 0.06 and
from 0.18 ± 0.06 to 0.99 ± 0.02.
The R2 values for prediction equations for determination of body weight from
biometrical measurements varied from 0.184 to 0.198, 0.147 to 0.177, 0.230 to 0.242
and 0.364 to 0.380 at 90, 180, 270 and 360 days of age. Height at withers, rump
height, body length, hip width, heart girth, Paunch girth and fore-cannon bone length
had significant influence on body weight.
The dwindling germplasm of the Deccani breed which is a native breed of
Telangana state can be conserved by selection of good animals from the results
obtained in the present study and improving the managemental and climatic
conditions.
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