Effect of livestock management practices (organic, “low input” and conventional) on the nutritional quality and safety of foods
Results from recent surveys in some European countries suggest that differences occur between organic, “low input” and conventional livestock production systems with respect to:
- Nutritional composition and/or shelf life of livestock products and
- Pathogen transfer risk into the food chain.
Surveys into nutritional quality of livestock products (e.g. milk, meat) have indicated that there may be significant difference in nutritional composition, taste and shelf life between organic, “low input” and conventional systems. In particular, differences in livestock feeding regimes appear to affect the composition of nutritionally relevant components in milk, such as fatty acid composition, including the content of conjugated linolenic acid (CLA), which has been linked to a reduced risk of obesity in humans.
Animal products with a high content of polyunsaturated fatty acids, CLA, antioxidants such as carotenoids and vitamin E (compounds which are often increased in milk from fresh grass forage fed animals) are preferable from a nutritional point of view, but the same compounds make the food more susceptible to oxidation, resulting in a greater risk of accumulation of undesirable off-flavours.
However, there is limited information on the relative importance of specific production system components (breed, feeding and veterinary regimes, husbandry methods) for differences in quality observed between production systems. Differences in production systems (e.g. organic / conventional,) may be confounded with differences in management. These deficiencies are addressed below.
The hosting of enteric pathogens by livestock, and the subsequent shedding of pathogens at slaughter poses a significant risk for the transfer of pathogens into the food chain. Recent studies showed that the proportion of pigs from organic production systems testing positive for antibodies against Salmonella was not different from pigs reared in indoor production systems, while the proportion of antibody positive pigs tended to be higher in conventional free-range production systems. However, the methodologies (test for Salmonella antibodies) used in this and similar studies may not have accurately reflected pathogen transfer risk. For example, when livestock test positive for antibodies against specific enteric pathogens this may not be associated with high levels of pathogen shedding in the faeces (which is a more objective indicator of pathogen transfer risk). The presence of antibodies could on the contrary (i) indicate that the animal has acquired immunity through exposure to the pathogen at an early development stage and (ii) be associated with low levels of pathogen shedding.
Feeding regimes and stress associated with transport of livestock has been shown to increase pathogen shedding in pigs and is therefore a potential confounding factor in comparative studies.
Studies to be carried out
To address theses deficiencies in knowledge we will carry out the following studies (sub-workpackages):
WP2.2.1: Effect of dairy management practices (organic, “low input” and conventional), and nutritional regime on the nutritional quality and shelf life of milk
The survey-based study will focus on quantifying quality differences between and within production systems; to identify which management aspects are most important in this respect. The identified aspects will subsequently be further investigated in experimental workpackages under SP2 and SP4 (see WP2.2.2)
WP2.2.2: Effect of dairy management practices (organic, “low input” and conventional) on production efficiency, milk quality and herd health status and reproductive efficiency
This study will follow up on WP 2.2.1. by comparing the effect on animal performance of selected management practices, such as feed types (e.g. perennial ryegrass, hybrid ryegrass, high sugar cultivars, naked oat and/or white clover) and conservation methods (hay, silage) in organic and conventional production systems. It will use an existing long term comparative (organic vs conventional) dairy experiment. There will be no double funding of the work
The focus will be on specific measures to increase the nutritional quality of milk, and production efficiency and costs, and the variation of these between production systems. The final design of WP2.2.2 will depend on data/deliverables from WP2.2.1. It is therefore scheduled for after the first 18 month. An open call will be made to identify a partner for this study
WP2.2.3 Effect of pig management practices (conventional, “low input” and organic) and transport on the risk of pathogen shedding at slaughter.
This survey-based study will measure pathogen shedding. It will focus on identifying if and how production systems affect the risk of pathogen shedding. The starting point is the high frequency of exposure to enteric pathogens in free-range production systems.