Increasing milk yield affects sustainability of dairy cattle production in terms of cultural energy use efficiency

Abstract Text: Purpose of this study was to conduct cultural energy analyses of dairy cows having different levels of milk yield. Cultural energy (CE) is the energy other than solar energy needed to produce food and fiber and energy output/input ratios is one of the most useful methods to examine the potential long-term sustainability of various agricultural practices and this analysis is performed to quantify the energy return from products produced relative to the CE invested to produce the product. Study was conducted at a commercial dairy farm, which specialized only in dairying and had 175 heads lactating cow during a production year which covered December 15, 2010 through December 15, 2011. At the farm lactating cows were grouped into four levels according to their milk yield and were fed accordingly. Groups were classified as low (LO), low-intermediate (LI), intermediate (IM) and high (HI). At the first visit to the farm a file that recorded milk production of each cow and number of lactating cows per group was formed and these records were recorded for every day. Feed intake of cows was also recorded every day. Cultural energy used for feed and other production inputs was derived from their corresponding feed consumption and resource expenditure and their corresponding values from literature. Energy value of the milk comprised the output. Total cultural energy expenditure increased as milk yield increased (P<0.05). Cultural energy expended for feed constituted more than half of the total cultural energy expenditure and increased as milk yield increased (P<0.05). Cultural energy expended per kg milk and per Mcal protein energy decreased as milk yield increased and was lowest for HI group (P<0.05). Energy use efficiency defined as the Mcal input/Mcal output was better for HI and worse for LO and as milk yield increased energy use efficiency became better (P<0.05). Results show that higher yielding lactating cows convert cultural energy into food energy better than lower yielding cows. Thus optimum milk yield not interfering cows’ health should be sought for sustainable dairy production.

Keywords: dairy cattle, milk yield, sustainability, cultural energy