Abstract
The study was carried out to investigate the phenotypic and genetic parameters of body weight and growth traits, milk
production and reproduction traits of Red Chittagong Cattle (RCC), an indigenous cattle of Bangladesh. For that
purpose accumulated data on a total of 330 animals from four different Herds (Anwara and Chandanaish Upazila in
Chittagong district, Bangladesh Agricultural University (BAU) Nucleus Herd and Char Jailkhana Community Herd in
Mymensingh district) covering a period from 2005 to 2010 were used. The genetic and environmental factors that
affected the performance of the individuals were looked at. The fixed factors considered for analysis of the traits were
herd, age, parity or lactation number, season, year, sex and sire. Data were analyzed by General Linear Model (GLM)
procedure of SPSS 11.5 version program to find out the least squares means and least significant difference for fixed
factors in every trait. The least squares means of live weight and growth traits were 15.9±0.4, 46.8±3.1, 67.6±26.2 kg
and 157.5±15.9 and 176.9±24.3 g/d, respectively for birth weight (BW), 205 day weaning weight (205dWW),
yearling weight (YW), pre-weaning daily weight gain (WDG) and post-weaning daily weight gain (PWDG). The
factors having significant effect on weight and growth traits were sex on BW, herd on 205dWW and WDG, season of
birth on BW, year of birth on BW and 205dWW and sire on WDG. Calving parity of dam had no significant effect at
all on those relevant traits. The least squares means of lactation length (LL), lactation milk yield (LMY), daily milk
yield (DMY), 305-day milk yield (305dMY) and days dry (DD) were 248.6±6.2 days, 598.6±21.8 kg, 2.3±0.1
643.1±14.9 kg and 148±10 days, respectively. The factors that affected milk production traits were herd on all milk
yield traits except DD, parity on LMY and DMY, calving season on LL, calving year on all traits except DD. The
least squares means of age at puberty (AP) and age at first calving (AFC) were 37.5±1.0 and 49.7±1.1 months,
respectively and there were no differences among herds. The least squares means of fertility traits were 1.4±0.1 no,
65.5±6.7, 81.5±3.7 and 63.1±5.7%, respectively for number of services per conception (NSC), first service conception
rate (FSCR), gross conception rate (CR) and non-return rate to first service (NRRFS). None of the environmental
factors contributed significant effect on these fertility traits. The least squares means of reproductive traits were
kg,
278.6±0.6, 131.4±6.7, 141.2±8.4 and 422.8±9.7 days and 83.6±1.4% for gestation length (GL), postpartum estrous
period (PPEP), days open (DO), calving interval (CI) and breeding efficiency (BE), respectively. The conception rates
at different services were 67.7, 23.9, 6.2, 1.3 and 0.4% for 1st, 2nd, 3rd, 4th and 5th+ services, respectively. The only
the
environmental factor that affected the reproductive trait significantly was season of conception on gestation length.
Unlike gestation length, all other reproductive traits were not affected by all factors included in this study. Milk
production of cows was found to have no significant effect on their BE. There was no seasonal influence on
estrous or reproductive behaviors in the RCC herds. The effects of screening while forming on-station nucleus herd
was highly significantly negative for milk production traits, whereas both negative and positive values (even though
not significant) for other traits studied were observed. Genetic parameters were estimated by Restricted (Residual)
Maximum Likelihood (REML) procedure using animal model. The heritability of weight and traits were
to
growth
medium to high ranging from 0.15 to 0.47 and their corresponding progeny repeatability estimates were low
medium ranging from 0.07 to 0.31. The heritability and repeatability estimates of milk yield traits were estimated
from low to high ranging from 0.02 to 0.61 and 0.03 to 0.59. The heritability of monthly test day (TD) milk yield
ranged from 0.42 to 0.66. The heritability estimates of cumulative monthly TD milk yield ranged from 0.54 to 0.79.
to
The phenotypic and genetic correlations among weight and growth traits were positive and low to high ranging from
0.04 to 0.98 and 0.12 to 0.98, respectively. The phenotypic and genetic correlations between lactation milk yield and
days dry were moderate (-0.33 and -0.42, respectively) and significant. The phenotypic and genetic correlations
among reproductive traits were very low to very high ranging from -0.36 to 0.77 and -0.36 to 0.79, respectively. The
phenotypic and genetic correlations between productive and reproductive traits were very low ranging from -0.19
0.06 and -0.27 to 0.03, respectively. Breeding values were estimated for milk yield traits only. Animals were ranked
according to their estimated breeding values (EBVs) ranging from -90.2 to 114.9 kg for 305 day milk yields and -0.8
to 0.9 kg for TD milk yields. The Pearson's product-moment, Spearman rank and Kendall's rank correlations between
EBVs for 305-day and TD milk yields were significantly (p<0.01) high (0.74 to 0.92). The expected genetic gain as a
result of one generation of selection was predicted with selection differential multiplied by heritability of the trait. The
observed or actual genetic gain due to first generation parent selection was estimated from the deviation between the
phenotypic mean of the progeny of the selected animals and parents selected for breeding. The expected response for
DMY was 0.04 kg per generation while that of observed/actual response decreased of -0.43 kg in the next generation.
Considering the performance, variation in traits within population, estimates of heritability, repeatability and
phenotypic and genetic correlations of the studied traits, it has become apparent that there is still chancе
improvement of RCC population if continual introduction of screened superior RCC bulls into the Nucleus Herd and
rigorous female selection based on their estimated breeding values is continued.