Assessment of input and energy consumption in dairy farms with different housing systems

Today, responding to the growing demand to food for increasing the world’s population and providing adequate food is one of the main causes of energy requirements in agriculture operations. Effective use of energy is an important condition for sustainable agricultural production which saves the cost, preserving fossil fuels and reduces air pollution. The animal husbandry sector plays an important role in providing the food security to the community by producing livestock products. Dairy farms play a significant role as the consumers and producers of energy. The livestock production is the poor converter of energy, because it is based on a double energy transformation. First, solar energy and soil nutrients are converted into biomass by green plants. Second, when crops are fed to livestock, a major share of energy intake is spent on keeping up body metabolism and only a small portion is used to produce meat and milk. Increased energy efficiency and utilization of non-renewable energy are effective to improve the air quality and also to reduce the greenhouse emissions. The aim of this study was to compare the input and consumed energy in dairy farms with different housing Systems. To carry out this research, the required information was collected from 42 dairy farms in the west of Tehran province. The studied dairy farms had an average milk yield of 31.94± 3.2 kg per day for milking cows and 195.42± 10.18 days in milk. The information included the unit consumption inputs over a one-year period aimed at comparing energy consumption and energy production between dairy farms with different housing Systems. The consumed energy included the non-renewable energy such as fuel and electricity and renewable energy such as forage, concentrate, machines, human labor, and water. Output energy included milk, meat, and manure. In order to compare energy efficiency between dairy farms, energy indices (energy ratio, net energy, energy productivity and specific energy) were used. The data were analyzed by SAS software. In this study, the average non-renewable consumed energy in dairy farms with freestall and open shed facilities per kg fat and protein corrected milk (FPCM) was 3.34 and 5.01 MJ, respectively (P=0.08). The highest share of the consumed energy in all dairy farms was related to feed energy, which had a share of 86.69% and 81.91% in the freestall and open shed, respectively. Also, the water input with consumption of 0.009 m3 per kg FPCM in freestall showed significant difference with open shed with consumption of 0.011 m3 per kg FPCM (P=0.04). Electricity consumption per kg FPCM in freestall and open shed was calculated to be 0.92 and 0.13 kWh, respectively (P=0.11). The rate of indirect energy was greater than that of direct energy consumption in both types of farms. The calculated output energy was 3.33 and 3.34 MJ per kg FPCM in freestall and open shed, respectively. The energy ratio for freestall and open shed were calculated to be 0.15 and 0.14, respectively. In addition, the energy productivity for freestall and open shed were 0.046 and 0.041, respectively. Energy indices can be improved by increasing the inputs efficiency, by reducing losses of inputs per cow or by optimizing inputs. In freestall farms, losses of inputs are lower than open shed farms. These results indicate better management of inputs in freestall farms. In freestall farms, because of the high density per unit area, consumption of inputs per head and per kilogram of FPCM was lower, indicating less waste of input and energy consumption. Considering the non-renewable consumed energy per kg FPCM, dairy farms with different housing systems (freestall vs open shed) tended to have difference. Among energy inputs, the energy of concentrate and forage (feed) consumption had the largest share of dairy farms. Also, considering the energy content of consumed feed as the main source of energy intake, special attention should be paid to prevention of energy waste throughout the suitable feed management as well as correct animal grouping. The use of proper feeding management, animal grouping, using several indicators (production, days in milk, body condition score, etc.) and breeding programs (according to production efficiency and yield traits) can improve feed consumption as the main source of energy consumption in dairy farms. Furthermore, the consumption of inputs per kg FPCM in freestall units was lower than open shed units.