Pasture feeding

Weide,/. willow pasture, pasturage, weiden, v.t.. pasture, feed. 

In a recent study of range cattle, the overall prevalence of serotype 0157 H7 from fecal samples was 1 % and this parameter was only 0.6% in animals that were on cow-calf pasture (Renter et al., 2003). New Zealand is a major cattle producing country that relies mostly on pasture feeding, but epidemiological evidence and cattle surveys suggested that the prevalence of E. coli 0157 H7 appears to be extremely low in that country (Cook, personal communication). Other researchers reported only two 0157-positive animals in a study that included 531 cattle in 55 dairy farms (Buncic and Avery, 1997). In studies conducted by New Zealand s Ministry of Agriculture and Forestry, E. coli 0157 H7 was never detected from a total of 3000 bovine and 500 ovine carcasses (Cook, personal communication). Based on these reports, it is apparent that cattle fed pasture had a lower 0157 H7 prevalence, but further work is needed to determine if the effect is due to the pasture feed itself or to the physical separation of the animals. 

Ayres, J.F. (1991) Sources of error with in vitro digestibility assay of pasture feeds. Crass and Forage Science 46, 89-97. 

Van den Hoek, J., Kirchmann, R.J., Colard, J. Sprietsma, J.E. (1969) Importance of some methods of pasture feeding, of pasture type and of seasonal factors on85 Sr and 134Cs transfer from grass to milk. Health Physics, 17, 691-700. 

Precht and Molkentin (1997) have identified and quantified a number of /rans-octadecadienoic acids in milk fat, containing one or two trans-double bonds (Table 1.4). Most of these acids are present in small amounts, with only lit, 15c-18 2 (0.33%) and 9c, 11/-18 2 (0.85%) having average concentrations above 0.30%. These /rans-octadecadienoic acids show considerable variation for instance, 9c, lit 18 2 ranges from 0.25 to 1.95%. Similar to /ra/tv-octadecenoic acids, pasture feeding produces higher levels of tram-octadecadienoic acids compared to the feeding of mixed rations. 

The principal factor that influences the a-tocopherol content of milk is the feed of the cow, as influenced by the season of the year. Kanno et al. (1968) reported that summer milk produced on green pasture feed averaged 33.8 pg a-tocopherol/g fat, while winter milk produced on dry-lot feeding averaged 21.6 pg a-tocopherol/g fat. Similar findings have been reported by King et al. (1967) and Seerless and Armstrong (1970). 

The milk fat composition is the most variable among natural edible fats. It is influenced by feeding and animal factors such as breed, stage of lactation, health, and age of the cow. The feed has the highest influence on the FA composition. Milk fat from pasture feeding has considerably more Cjg FA and less C16 0, C14 0, and C12 0 acids than fat from indoor feeding. Short-chain FA (C4 0 to C8 0) are characterized by the smallest seasonal variation (Table 13.4). 

In summary, pasture feeding seems to be an effective tool to produce raw materials of outstanding biological value. However, with respect to CLA, its efficiency seems to... 

Cassar-Malek, 1., C. Jurie, C. Bernard, 1. Bamola, D. Micol and J.E Hocquette, 2009. Pasture-feeding of Charolais sleets influences skeletal muscle metabolism and gene expression. J Physiol Pharmacol. Suppl 3, 83-90. 

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