Economic and genetic evaluations of different dairy cattle breeds under rural conditions in Bangladesh

M K I Khan, G Miah, K S Huque*, M J Khatun and A Das

Chittagong Veterinary and Animal Sciences University, Khushi, Chittagong-4202, Bangladesh.
kkhan1567@yahoo.co.uk,
* Bangladesh Livestock Research Institute, Savar, Dhaka-1341, Bangladesh.

Abstract

The study was conducted for the economic and genetic evaluations of Red Chittagong Cows (RCC), Local and Holstein × Local crossbred cows under the rural area in the Chittagong district of Bangladesh. For economic evaluation, profitability per cow per year of RCC, Local and Holstein × Local crossbred was estimated using a deterministic linear model. The economic values of different traits (milk yield, live weight and calving interval) were calculated from this model after re-running with changes one unit of each trait and maintaining the other traits in the model as constant.

 

For one-year operation, the RCC showed intermediate profit, but in consideration of life-time yield and calving interval, it was found that RCC generated higher profit than the Holstein × Local crossbred and Local cows. The economic value of milk yield was found positive but for live weight and calving interval was found to be negative value for different genotypes and that varied among them. Best linear unbiased prediction (BLUP) estimated breeding values (EBV’s) of milk yield, live weight and calving interval were obtained from a   univariate  animal model and the economic selection index or total merit was constructed as the sum of the product of estimated breeding values with the economic values of each trait. It was found that the BLUP estimated breeding values (EBV’s) of different traits were differed with the differences of genotype. The economic selection index, there were a favorable combination between of genetics and economics.

Keywords: Breeding values, economic values, genotypes, profitability, total merit

Introduction

The majority of studies on dairy cattle breeding in the tropics, including Bangladesh have been biological involving comparisons of productive and reproductive performances. Some economic evaluations of dairy cattle crossbreeding strategies have been conducted under temperate conditions (Lopez-Villalobos et al 2000; Steine et al 2006). These studies showed that crossbreeding results sufficient heterosis to provide greater economic return than the best of the existing breeds. Although there were some economic evaluation studies have been conducted under tropical conditions which were incomplete or including with missing information (Gunjal et al 1997) or sometimes involved a single breed (Kahi et al 2000; Khan et al 2010), they considered only returns from sales of milk and manure, and the costs associated with milk production, in their economic evaluation. Within genotypes, profit function was used to estimate economic values (Kahi and Nitter 2004) which are required to define breeding objectives and to predict revenues from breeding programmes. Unfortunately, detailed economic assessments of costs (C) and revenues (R) of dairy cattle breeding for tropical areas including Bangladesh are rare.

 

Genetic evaluation studies have been used to select sires and elite cows for the genetic improvement of dairy cattle. For selection of the best individual an effective approach is the selection index method (Hazel et al 1994), which is a weighted linear function of selection criteria and breeding value for each trait in the breeding objective with weights reflecting their relative importance. It is crucial to estimate the breeding values and economic values for the traits in the breeding objective. The genetic merit of an animal has been undertaken based on different models (e.g. sire model/ individual animal model). Parameters in a model can be estimated by several ways such as least square methods (LSM), restricted maximum likelihood (REML) and best linear unbiased predictions (BLUP). Both the single and multiple trait, BLUP method are used to evaluate the animals. Compared to other methods, BLUP estimated breeding value (EBV) is more accepted approach, which increases the accuracy of estimation and enables simultaneous estimation of genetic and environmental effects (Cilek and Kaygisiz 2008).

 

In Bangladesh, dairy cattle genetic improvement programmes have been conducted since 1970. However, these genetic improvement programmes were not successful or satisfactory due to ill-defined breeding objectives, inefficient artificial breeding programme, small population size, improper recording, lack of necessary infrastructures and skilled personnel. To run a structured genetic improvement programme it is essential to undertake the economic and genetic evaluation studies on the available genotypes. Therefore, the present study was undertaken with the objectives (i) to estimate the profitability of different cattle breed groups (ii) to calculate the economic values for different traits in the breeding objectives (iii) to estimate the breeding values of different traits and (iv) to construct an economic selection index or total merit for individual cow.

Materials and methods

A total of 300 RCC farms consisting of 360 RCC, 150 Local and 110 Holstein ´ Local crossbred cows (genetically unrelated)  from the five Upazilla or administrative subunit (Satkania, Chandanaish, Anwara, Potia and Raowzan) in the Chittagong district (administrative unit) of Bangladesh were considered in this study. Data were collected with a structured record sheet from July 2008 to June 2010 through fortnightly farm visit physically by the data collector. From the recorded data, the average herd level production variables for all three genotypes (RCC, Local and Holstein ´ Local crossbred) were estimated using PROC GLM of SAS (2000) (Table 1).

 

Breeding, production and marketing system

 

Dairy production in Bangladesh are mostly integrated with crop farming with 1-2 cows and 0.20 hectares of land per farmer is typical and the herd consists of mixed breed but in the study area the RCC was more concentrated. The farmers breed their RCC cows with the semen of RCC bull supplied by the Central Cattle Breeding Station (CCBS) of Bangladesh and from the Bangladesh Rural Advancement Committee (BRAC) inseminators; moreover, the RCC community breeding station was formed with the RCC bulls. The farmers can use these bulls for natural service to their cows. Local cows are mostly served by natural mating with the available local bulls and the temperate crossbreds are inseminated with the semen of Holstein or available breeds. Generally, all calves are fed colostrum during the first 3 to 5 days and then approximately 0.5 to 1.0 kg or as availability of whole-milk are fed daily from approximately 2 to 3 months. Thereafter, and up to weaning they fed whole-milk with roughages, and little amount of concentrate. From weaning to age at first calving heifers are offered little amount of concentrate, roughages and grazed on the road side, fallow land etc. During monsoon the cattle are mainly fed with paddy straw. The lactating cows of RCC and Local are fed with a concentrate mix approximately 1-1.5 kg/day throughout the year. However, the Holstein x Local the amount of concentrate mix are higher approximately 2 to 3 kg/day per cow throughout the year. The concentrate mix includes rice polish, brans and oil cakes. The male calves are castrated and used for draft very few numbers of bulls are kept for breeding purpose. The culled cows and the surplus heifers are sold for slaughter or other purposes. Other management practices, such as vaccination and de-worming are undertaken on most of the RCC community farms. The household members are rears their cows therefore labourer costs is minimum. The farmer members sale their milk direct to the market or sometimes to the middle man, who pool their milk and arrange the advanced cash payment on the basis of milk volume.

 

Economic evaluations

 

A deterministic linear programming model, context using Microsoft Excel was used according to Khan (2009) and Khan et al (2010) to estimate the profitability of RCC, Local and Holstein ´ Local crossbred cows. The economic analyses were done based on average values of marketable products (milk and meat) and the expenses incurred in dairy production (feed costs, health, reproduction and fixed costs). The profit was derived as the difference between revenues (R) and costs (C). The main components considered in this model were herd structure (population dynamics), nutrition, biological and economics of the farm.

 

The input parameters of RCC, Local and Holstein ´ Local crossbred are presented in Table 1. The total metabolisable energy (ME) requirement per cow per year was the sum of ME requirement for maintenance, growth, pregnancy and production and was calculated according to AFRC (1993). The milk production per lactation was considered as milk production per calving interval and the milk yield (kg/year) was calculated as:

                      

Milk yield (kg/year) = Milk yield per lactation (kg) x 365/ Calving interval

 

The dry matter (DM) requirements were calculated by the content of ME per kg DM. It was considered that cows were consuming roughage from grazing, paddy straw, tree leaves and 1- 2 kg concentrate mix (brans, oil cakes and grains) per day for RCC and Local cows and 2- 3 kg for Holstein ´ Local crossbreds, to fulfill their energy requirements. The feed cost (roughage and concentrate mix) for different genotypes were calculated at 0.09 – 0.12 US$ per kg DM. The revenue was derived from the differences of the sale of milk and beef, and the cost of feed and fixed costs (operational cost).

 

In the model, the livestock classes were calves, heifers, steers and dairy cows. Dairy cow replacement can be reared from the calves born within the herd. Generally the heifers are mated at 2-3 years of age to calve at 3-4 years of age. The farmers keep the Local and RCC cows up to 10 years of age that is up to 7 lactations but they keep Holstein and their crossbreds up to 3 lactations only because of lower productivity due to poorer adaptability. The lifetime profitability was estimated by the product of yearly profit per cow and the lactation number of cows.

 

The individual cow income was estimated after running the base model and the economic values (EVs) of milk yield, live weight and calving interval was obtained by re-running the base model after changing one unit of each trait while maintaining the other traits in the model at a constant level. 

 

Estimated breeding values (EVBs) for different traits

The EBVs of different traits (milk yield, live weight and calving interval) were estimated from a univariate analysis by AIREML, based on Restricted Maximum Likelihood (REML) using the average information (AI) matrix as second derivatives in a quasi-Newton procedure (Johnson and Thompson 1995). The animal model for analysis of three traits was presented as:

Y= Xb + Zu +e

Where, Y is the vector of all observations;

              b is the vector of fixed effects considering the effect of location and cow age;

              u is the vector of breeding value of the animal's, random; and

              e is vector of residual effects.

 

X and Z is design matrix connecting to the fixed and random effect, respectively.

There was no sire, dam and grand sire information only the individual cow’s performance was considered in this analysis. The heritability values used in this model for different traits are shown in Table 2.

For the (co)variance of Y the assumption is:

var(u) = G

var(e) = R

and

cov(u,e) = 0

which gives

 

A univariate animal model was used to estimate the breeding values of animals and then

 

var(e) = R = Iσ²

one random effect u = a,

design matrix Z = Z_a and

variance matrix G =A.σ_a²,

where, A is the relationship matrix.

The mixed model equation (MME) thus became:

 

 Construction of economic selection index or total merit

 

The economic values of different traits can vary between breeds and place to place, depending on the variable production system. In addition, it may also vary with the fluctuations in prices and costs of input and output variables of farm. Therefore, in the present study, the economic value was estimated under the same situations and used to develop the economic selection index or total merit. Here the economic selection index or total merit value of the selection objective of milk production was calculated as the sum of the product of BLUP estimated breeding values with the economic values of all traits (milk yield, liveweight and calving interval). The economic selection index was expressed in dollar. An estimate of T (known as total merit) was calculated as:

Total merit (T) = a_MY G_MY+a_Lwt G_Lwt+a_CIG_CI

Where, G_MY, G_Lwt and G_CI are the estimated breeding values for lactation milk yield, liveweight and calving interval and

a_my, a_Lwt and a_CI are the respective economic values.

Results

Performance and unit prices of different variables for various breed groups

 

The average productive and reproductive performances and unit prices of different variables for various breed groups are presented in Table 1. From the Table 1 it can be seen that the Holstein × Local crossbred showed superior performance than RCC and Local genotypes except the survivability and calving interval. RCC was superior for these two traits. The milk, meat and feed prices were similar for all the three breed groups.

 Economic evaluations of different breed groups

 

Table 2 shows the costs, revenues and profit of RCC, Local and Holstein × Local crossbred cows under RCC community farming on a per cow per year basis. Table 2 indicates that the average net income of Holstein × Local crossbred (US$ 101) was higher than RCC (US$ 54) and Local (US$ 40) cows. Total revenue was dominated by the sale of milk (73 -78%) and beef (19-23%). Feed costs accounted about 86% of the total costs. Health costs, reproduction costs, labour costs, marketing costs and all other operational and management costs were assumed to be fixed costs. Local cattle had the lowest dry matter (DM) requirements for maintenance, growth of replacements and lactation where Holstein ´ Local had the highest total DM requirements and RCC had at intermediate level (Table 2). However, the Holstein ´ Local had the highest milk and beef revenue and that generated highest profit than other genotypes.

 The economic values of different traits under rural conditions of Bangladesh for three different genotypes also are shown in Table 2.  The economic value of milk yield for different genotypes was positive and slightly varied among different genotypes. The economic values of calving interval and mature live weight were negative and varied between genotypes.

 

Estimated breeding values for the different traits

 

The estimated breeding values for different traits (lactation milk yield, live weight and calving interval) of RCC, Local and Holstein × Local crossbred cows under rural conditions of Bangladesh are shown in Table 3. The estimated breeding values of lactation milk yield, live weight and calving interval for RCC ranged from 78.2-302.8 kg, -10.9- 41.1 kg, and -8.5-12.6 days, for Local  12.7-80.9 kg, -2.7-5.5 kg and -1.2- 0.6 days and for Holstein × Local crossbreds from -7.5-134 kg, -19.9 to -38.1 kg and -4.9 - 9.4 days, respectively (Table 3). The estimated breeding values for lactation milk yield and live weight of RCC were higher than that of Local and Holstein × Local crossbreds.

 

Economic selection index or total merit

 

The economic selection index or total merit for RCC, Local and Holstein × Local crossbreds under rural conditions of Bangladesh are presented in Table 3. As an example, only top ranked ten cow’s economic selection index or total merit is shown in the Table 3. The economic selection index or total economic merit for RCCs ranged from US$35.2 - US$100.3for Local US$ 2.28 – US$30.73 and for Holstein × Local crossbreds were from US$ 4.5 - US$66.1.