Study the Live Weight and Live Weight Gain of Black Bengal and Jamunapari Goat Breeds by Fitting the Linear Regression under Semi-intensive Conditions

MATERIALS AND METHODS

The study was conducted at two farms in Panchlaish Thana under the district of Chittagong of Bangladesh from July 2012 to January 2013.

Management of goats: The goats were kept in the dry and high placed bamboo sliced made well ventilated house with sufficient floor spaces. Fifteen goats were reared in one shed. There was no separate shed for male or female and for kids of black Bengal goat and Jamunapari goat. The goat was allowed to graze in the field about 5-6 h. Feed was provided three times in a day at morning, noon and afternoon and keep adequate water supply during feeding. In addition, some concentrates like broken rice, rice gruel, wheat bran, motor bran, gram chuni, banana residues was supplied and during the scarce period of time they fed the goats tree leaves, herbs, etc., Kids are fed milk from their dam up to weaning. All does were naturally mated. At the end of estrus the goats were allowed for natural service. A matured buck is used for 25-30 does. Regular/periodic de-worming is practiced. Goats are vaccinated against PPR. A veterinarian are regularly inspecting the farm to observe the health status of goat and treated them if the goats are suffering from any diseases or diseases condition like anorexia, diarrhea, PPR, difficulty of kidding.

Study of live weight and live weight gain: Data were collected from 72 black Bengal goats and 32 Jamunapari goats of 2 different farms. Birth weight of kids was taken within 24 h after birth. The kids birth weight and subsequent live weight at weekly interval up to sexual maturity were recorded for estimates the birth weight, weight gains and age and weight at weaning up to sexual maturity. The goats were weighted by top loading balance during the study period.

Fitting the linear regression equation: The linear regression y = a+bx (where, x is the ages of goats and a and b are the parameters that define the shape of the curve) used to fitting the observed values of birth to weaning and weaning to sexual maturity. To obtain the model parameters, a (intercept), b (slope) and fit statistics, R² (Co-efficient of determinant) the above linear model was fitted with Microsoft Office Excel 2007.

Statistical analysis: The collected data were unequal which was tabulated in Excel and edited. The collected data were analyzed by using the statistical package (SAS, 2000). The following statistical models were used to obtain the least square means with standard error of all parameters.

The model is given as:

Y_ijkl = μ+B_i+S_j+F_k+e_ijkl

where, Y_ijkl is value of the traits, μ is the overall mean, B_i is the effect of Breed and S_i is the sex effect, F_k is the effect of farm, e_ijkl is the random error.

The mean differences were compared using least significant difference that (Isd) (Steel et al., 1997) at 5% level of significance.

RESULTS AND DISCUSSION

Birth weight: The birth weight of black Bengal and Jamunapari goat’s kids in two different farms is shown in Table 1. Average birth weight of male and female black Bengal goats kids were 1.22±0.15, 1.01±0.14, 1.42±0.10 and 1.12±0.27 kg, in farm 1 and 2, respectively. From Table 1, it can be seen that the birth weight of male and female were varied in two different locations. The average birth weight of black Bengal male kids were higher than the female kids in both locations. However, the average birth weight of male and female black Bengal kids of farm 2 were higher than farm 1.

The average birth weight of Jamunapari male kids (1.51±0.07) were higher than female kids (1.42±0.09 kg). The average birth weights of both sexes of Jamunapari were higher than black Bengal goats. The birth weight depends on breed, feeding, location, care and management e.g., over all health hygiene of pregnant does.

Table 1:	Birth, Weaning and sexual maturity weight (kg) and weight gain (g day-1) from birth to sexual maturity of black Bengal goats and Jamunapari Goats under two different farm
Letter a and b in the superscript indicated 5% (p<0.05) level of significant

In this study the average birth weight of male kids at farm 2 were higher than farm 1. In case of female kid’s birth weight were higher in farm 2 than 1. Comparatively male kids birth weight showed different between two farms than female kids. There was a negative association between birth weight and Litter size. In this study the birth weight of black Bengal goat was similar with Talukder et al. (2010) but lower than Khan and Khatun (2013), they reported birth weight of kids 1.0-1.3 and 1.5-1.9 kg, respectively. Hassan et al. (2010) found the mean body weight of Jamunapari kid was 1.6 kg at birth which was similar to present study.

Weaning weight: The weaning weights of black Bengal and Jamunapari goats are presented in Table 1. The average weaning weight of male and female black Bengal goats were 5.19±0.358, 5.05±0.28, 5.63±0.61 and 5.54±0.41 kg, respectively for farm 1 and 2. From Table 1, it was found that the average weaning weight of male black Bengal goat was higher than female in both farms. The reverse results were observed for female kids. However, the average weaning weight of male and female black Bengal kids of farm 2 were higher than farm 1. The average weaning weight of male and female Jamunapari was 6.59±0.69 and 6.79±0.31 kg, respectively in farm 2. The average weaning weight of Jamunapari female was higher than Jamunapari male. Though the birth weight of Jamunapari male was higher than female kids but the weaning weight of female Jamunapari was higher than male Jamunapari goat. The average weaning weight of male and female Jamunapari was higher than male and female black Bengal for both farms. In the current study the weaning weight of black Bengal goat was similar with Chowdhury et al. (2002) but lower than Khan and Khatun, (2013). They reported weaning weight of goats 4.87-5.5 and 6.5 to 7.5 kg, respectively.

Age and weight at sexual maturity: The age and weight at sexual maturity of black Bengal and Jamunapari goats are presented in Table 1. The average weight at sexual maturity of male and female black Bengal goats were 9.82±0.75, 9.52±0.62, 9.65±0.75 and 9.138±0.70 kg in farm 1 and 2, respectively. From Table 1, it was found that the average weight at sexual maturity of male black Bengal goat was higher than female in both farms. The reverse results were observed for female kids. However, the average weight at sexual maturity of male and female black Bengal goats of farm 1 was higher than 2. Though the weaning weight of male and female black Bengal goats of farm 2 were higher than 1.The average age at sexual maturity of male and female Jamunapari goat was 9 months which was higher than black Bengal goat. But the black Bengal goat attained sexual maturity at an early age than Jamunapari goat. The average weight at sexual maturity of male and female Jamunapari goats was 13.2±0.75 and 14.1±0.82 kg, respectively in farm 2. The average weight at sexual maturity of female Jamunapari goat was higher than male. The average age and weight at sexual maturity of male and female Jamunapari goats were higher than male and female black Bengal goats.

In the current study the age at sexual maturity of black Bengal goat was 8 months which was similar with Amin et al. (2001) but higher than Khan and Khatun, (2013), Rume et al., (2011) and Hassan et al. (2007). They reported that age at sexual maturity of goats were 7.2±0.18 kg. In this study the weight at sexual maturity of black Bengal goat was 9-9.8 kg which was similar with Rume et al. (2011), Hassan et al. (2007), Hossain et al. (2004), Chowdhury et al. (2002). They reported that weight at sexual maturity was 8.89±0.33 kg. In the current study the age at sexual maturity of Jamunapari goat was 270 days, where Hassan et al. (2010) found 354.7±17.1 days which was higher than present study. The variation of results was occurred due to genetic cause. Chowdhury et al. (2002) observed that season and feeding level of were affected of age at first heat but rearing system did not affect the age of puberty. Besides genetically influence, feeding and management are important in respect of age of puberty. The management includes feeding, breeding, housing and disease control which affect the age at puberty.

Average daily live weight gain
Birth to weaning: The average daily body weight gain from birth to weaning is presented in Table 1.The average daily body weight gain from birth to weaning for male and female black Bengal goats was 33.70 and 35.11 g day^-1, respectively, in farm 1. In case of farm 1, the average daily body weight gain from birth to weaning of female black Bengal goat was higher than male black Bengal goat, although the average birth and weaning weight of female was lower than male. Therefore, it can be seen that the female goat attained more weight than male black Bengal goat in farm 1. But the average daily body weight gain from birth to weaning for male and female black Bengal goat is 35.67 and 45.94 g day^-1, respectively in farm 2. On the other hand the average daily body weight gain of female is higher than male (farm 2). But in farm 2 average daily weight gain of male and female is higher than male and female of black Bengal goat farm 1. But in farm 2 the average daily body weight gain from birth to weaning for male and female Jamunapari goat was 42.97 and 45.47 g day^-1, respectively. The average daily weight gain of female was higher than male. Therefore, female attained more weight than male black Bengal goat in farm 1. In both farm the average daily weight gain of female was higher than male for 2 different breed. But average daily weight gain of female black female black Bengal goat of farm 2 was attained highest gain than Jamunapari and also farm 1. Although, the average weaning weight of male and female Jamunapari was higher than male and female black Bengal for both farm. In the current study the average daily body weight gain from birth to weaning was 34-45 g day^-1 which was similar with Husain et al. (1997) and Khan and Singh (1989). They observed average daily body weight gain was 35-45 g day^-1.

Weaning to sexual maturity: The average daily body weight gain from weaning to sexual maturity are presented in Table 1.The average daily body weight gain for male of black Bengal goat was higher than female, although the average birth to weaning weight gain of female was higher. This difference was due to that in earlier stage the kids grew faster than the older age and was the effect of age sex and management. This result was similar with Husain et al. (1997), they reported that the average daily body weight gain weaning to sexual maturity was 44-55 g day^-1. The average live weight gain decreased significantly with increase in age (Husain et al., 1997).

Fitting the regression equation: After fitting the regression equation, with the data on birth weight to age at sexual maturity of different goat breeds the regression parameters and the value of R² are presented in Table 2. The intercept and slope of male black Bengal under farm 1 and Jamunapari goat was 0.429, 0.278, 0.966 and 0.310, respectively. The intercept and slope of Jamunapari goat was higher than black Bengal goat under farm 1. The co-efficient of determination (R²) of male black Bengal under farm 1 and Jamunapari goat was 0.992 and 0.998, respectively. The R² value of male Jamunapari goat was higher than black Bengal goat. So the value of male Jamunapari goat was more fitted. The higher R² values considered as superior (Khan et al., 2012). The intercept and slope of female black Bengal and Jamunapari goat was 0.252, 0.275, 0.603 and 0.343, respectively. The intercept and slope of female Jamunapari goat was higher than black Bengal goat under farm 1.

The co-efficient of determination (R²) of female black Bengal under farm 1 and Jamunapari goat was 0.994 and 0.956, respectively. The R² value of female was higher than Jamunapari goat. So the value of black Bengal goat was more fitted. The intercept and slope of male black Bengal and Jamunapari goat was and 0.938, 0.259, 0.966 and 0.310, respectively under farm 2. The intercept and slope of male Jamunapari goat was higher than black Bengal goat under farm 2. The co-efficient of determination (R²) of male black Bengal under farm 2 and Jamunapari goat was 0.996 and 0.956, respectively. The value of male black Bengal goat under farm 2 was higher than Jamunapari goat. So the value of male black Bengal goat was more fitted.

Table 2:	The regression parameters and R2 values after fitting the regression equation, with the birth weight to age at sexual maturity of different goat breeds

The intercept and slope of male black Bengal under farm 1 and 2 was 0.929, 0.278, 0.938 and 0.259, respectively. The intercept of male black Bengal goat under farm 1 was higher than 2. The co-efficient of determination (R²) of male black Bengal under farm 1 and 2 was 0.992 and 0.996, respectively. The R² value of male black Bengal goat Under farm 2 was higher than 1. From Table 2, it showed that the highest R² value 0.998 was observed in male Jamunapari goat. So the R² value 0.998 was more fitted and superior. In this study the R² value was higher than Khan et al. (2012). They observed the R² value was 0.93-0.95. However, the growth of goats could be influenced by sex, season, age, management. Similar factors were identified by various researchers (Najari et al., 2007; Thiruvenkadan et al., 2010).

CONCLUSION

The study reveals that the average birth weight, weaning weight, weight at sexual maturity and weight gain from birth to weaning, weaning to sexual maturity of male and female of black Bengal and Jamunapari goats were different in between farm. The study also showed that the weight gain of goat depends on birth weight, balance feeding, presence or absence of diseases, available milk from mother and management of kids. But some constraints in this study were small population size, presence of diseases, limited time and seasonal differences. However, more study with larger studied population and in different geographical region is recommended for making final comments.

ACKNOWLEDGMENTS

The authors express their sense of gratitude to the authority of Chittagong Veterinary and Animal Sciences University for their support and encouragements for this study. The authors are also grateful to the farmers of the studied farms.