Abstract
The present study was carried out to evaluate the performance potential of three
genetic groups as G1 (50% Brahman x Indigenous local), G2 (75% Brahman x
Indigenous local) and Indigenous local genotypes of cows under farm and rural
conditions. Pure Brahman frozen semen (100% ) were used for grading up local
cows. The study was conducted during the period of January 2014 to November
2018 in 80 upazilas of 38 districts of the country under the control of Department
of Livestock Services and Department of Animal Breeding and Genetics,
Bangladesh Agricultural University, Mymensingh with the financial support of
the Government project entitled "Beef Breed Development project " in
Bangladesh. A total of 5662 records for three genetic groups were analysed
statistically. The overall birth weight of Indigenous local, G1 and G2 graded
calves were 14.24±0.96, 23.39±0.07 and 31.62±0.72kg, respectively having
significant difference (p<0.001) from each other. All other body weights were
found highest for G2 followed by G1 and lowest for local genotypes. The highest
growth rate observed from 6-month to 12-month of age for G2 (1529.63±94.21g),
medium for G₁ (800.54± 4.75g) and lowest for Indigenous Local (333.50c±56.81g),
respectively with significant differences (p<0.01). As different agro climatic zone
Rajshahi had the highest average daily gain for Gi genotypе (414.40±8.46 g) for
the period of bwt-wt3 with significant variation (p<0.01) from Barisal
(361.39±11.65 g), Rangpur (380.81±6.28 g) and Sylhet (360.53±14.97g). The
mature live weight of G1, G2 and Indigenous Local bulls were 689.37±28.19,
889.16±32.55 and 211.71±21.31 kg, respectively with significant variation
(p<0.01). The weight just before slaughter for three genotypes were
675.12±31.19, 884.08±36.02, 209.50±23.58 kg, respectively and had same trend of
variation (p<0.01). The results were same for warm carcass (385.87±19.07,
541.00±22.03 and 102.92±14.42 kg) as well and dressing percentage (57.00±0.72,
60.94±0.83 and 49.03±0.54 percent).The heritability of G₁ was highest at wt24
(0.43±0.02) and lowest at wt3 (0.25±0.02). The highest h2 of G2 were 0.40±0.17 at
wt6 and lowest at wwt (0.34±0.02). Again the highest and lowest h2 of local
genotype were 0.34±0.02 and 0.25±0.10 at wt12 and wt6, respectively. It was
revealed that the estimation of individual heterosis for birth weight, wt12, wt24
and carcass weight were 2.84, 1.90, 0.24 and 9.44 respectively. Strong genetic and
phenotypic correlations for G1, G2 and Indigenous Local genotypes were found
at wt6, wt9 and wt12 respectively. Significant difference (p<0.01) were found in
for weight at first heat 343.19±5.44 kg and 166.31±18.24 kg as well as postpartum heat period 73.63±1.51 days and 51.37±5.09 days between G1 and local
genotypes, respectively. The highest breeding values were 43.5, 10.7, 19.5 and
44.0 for bull ID 7BR524, 14BR41, 7BR522 and 7BR527 at bwt, wwt, yearling and
mature weight, respectively. The overall results on productive and reproductive
performance of three genetic groups showed that introduction of Brahman meat
type breed could be an alternative authentic approach for increasing meat production in the rural areas of Bangladesh.