عنوان مقاله [English]
Introduction The best way to maximize the profitability through breeding is using economical coefficients of characteristics with genetic assessment. One of the effective ways to increase profitability in animal husbandry is using livestock breeding. It is not possible to utilize breeding optimized method without considering relative importance of characteristics economically. On the other hand, the best way to determine the relative importance of characteristics is to calculate the economic coefficients. Economic Value of characteristic is the profit obtained from one unit genetic improvement of the average of a characteristic when other characteristics are held in their constant values. Bio-economic model is a set of equations which define the incomes and costs of the production system as a function of different characteristics. Simulation is a process in which a set of examinations are carried out by using a designed method on the basis of a real system in order to find out the system behavior and various approaches are assessed for its operation in a defined range.
Materials and Methods The aim of the present study is to estimate the economic value of production and reproduction characteristics of dairy cows of Mohan cultivation, industry and animal husbandry based on collected data from 13000 dairy cows and market conditions in 2014 and by using a determined bio-economic model. The income factor included obtained incomes from milk sale, additional heifer sale, male calf, removed cows and fertilizer sale and the costs included nutrition, management and capital costs. The management costs included health and care, human forces and reproduction. Five different stages defined in animal life cycle. These stages including from birth to weaning, from weaning to the age calf sale (12th month), from weaning to the first insemination of female calf (18th month), from first insemination to first birth (alternative heifers) and productive cows more than two years old. The calculation of cost and revenue of the heifer per 18 months is carried out. The breeding period of calf, young cow and productive cow considered 12 months. In these herds, nutrition was done completely manually and in the place. Nutrition cost was calculated using energy requirements estimation equations AFRC (1991) by considering the consumed concentrate constant for productive cows, growing male and female calf and alternative heifers separately. In this system, artificial insemination is used for cows impregnate and reproduction cost considered as a function of interval of two births which indicates the number of insemination which resulted in impregnation. Health program included vaccination, deparasitation and quarantine. Male calf was sold based on each kilogram weight per each calf at a constant price. In present study, dairy cows in production system were categorized in seven different age groups of 2, 3, 4, 5, 6, 7, 8 and then revenues, costs, final profit and economic value of characteristics calculated for every age group separately. The studied characteristics include milk production, fat milk production, age of the first birth, calf birth interval, increasing daily weight before and after weaning, birth weight, matured calf weight and live rate before and after weaning. The bio-economic model designed based on breeding and information system of herd and economic coefficients calculated by matlab software. Economic value of each characteristic estimated based on the changes in annual profit of production system per one unit increase in the average of the considered characteristic while other characteristics are kept constant. First, all of the revenues and costs and profit and herd combination determined and the input files saved and the program ran.
Results and Discussion Annual revenues and costs calculated based on different age groups and the annual profit was 15966572/69 Rials for each productive cow. Among revenue resources, 71% was for milk sale and its components, 10% for removed cow sale, 11% for male calf sale, 6% for additional heifer sale and 2% for fertilizer sale. Among variable costs 68% was for nutrition costs, 17% for work force cost and livestock sale and 10% for health and reproduction costs. Economic values of production and reproduction characteristics including milk production, milk fat production, age of first birth, calf birth interval, daily weight increase after and before weaning, birth weight, matured calf weight and live rate before and after weaning estimated 4718/59, 144757/8, -30756/52, -86789/17, 1284/45, 34/57, 9894/16, -1900/13, 5808 and 107521/9 Rials per each cow respectively. The highest relative importance related to production characteristics (54/37%) and after that reproduction (21.98%), durability (20/56%) and the least amount estimated for growth (3/07%). Characteristics can be divided into several groups based on the impact on revenues and costs. Economic values of production and reproduction characteristics including milk production, milk fat production, age of first birth, calf birth interval, daily weight increase after and before weaning, birth weight, matured calf weight and live rate before and after weaning estimated 4718/59, 144757/8, -30756/52, -86789/17, 1284/45, 34/57, 9894/16, -1900/13, 5808 and 107521/9 Rials per each cow respectively. The highest relative importance related to production characteristics (54/37%) and after that reproduction (21.98%), durability (20/56%) and the least amount estimated for growth (3/07%). Characteristics can be divided into several groups based on the impact on revenues and costs. A group of characteristics increase the revenue and cost of production system and also increase the profit compared with the initial state (initial value). Most of the production characteristics such as milk production, fat, increase of weight before and after weaning, birth weight and live rate before and after weaning are placed in these groups. However, by increasing one unit of matured cow weight, the revenue and costs are increased and but the obtained profit is decreased. Characteristics of the second group do not impact the revenue but the costs of production system increased by increasing its average which include the age of the first birth. The third group includes the characteristic of interval between two births and the revenue decreased, system costs increased and profit decreased by increasing its average.
Conclusion Increase in the average unit production and reproduction traits have different effects on revenue, cost and profitability of production systems.