Effects of grazing conditions on alpine pastures on muscle growth, meat quality and fatty acid profile

Gangnat, Isabelle Diane Marie (2015). Effects of grazing conditions on alpine pastures on muscle growth, meat quality and fatty acid profile (Dissertation, ETH Zürich)

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Seasonal alpine pastures are an essential part of the traditional mountain dairy production in Switzerland, and they also arouse interest for extensive beef production. The characteristic pedoclimatical conditions on seasonal alpine pastures generate unique features in dairy products, which could also be expected in meat produced under these conditions. However, knowledge about performances and meat quality of beef cattle on alpine pastures is lacking. In the present project, the separate effects of the vegetation on seasonal alpine pastures on the one hand, and of their characteristic topography on the other hand, were studied in comparison with typical conditions of lowland grass fattening. The latter was represented by a cultivated lay to study the effect of vegetation or by a flat terrain to study the effect of topography, respectively. The effects of the alpine vegetation were tested on beef heifers whereas the effects of the alpine topography were tested on suckling beef calves. As a finishing period is often practiced by commercial farms after a stay on seasonal alpine pastures, the effect of a finishing period in barn was tested following the period where the effects of the alpine vegetation had been investigated. Additionally, different beef calf systems (suckling, weaned and mentored by experienced adults, or weaned and kept among themselves) on alpine pastures were compared. If growth performance was not affected by the native alpine vegetation, in comparison with performances obtained from a cultivated lay in the lowland, meat colour was found to be less yellow and less red with the alpine vegetation, and some of the expected fatty acid characteristics found in dairy products were retrieved in the meat. Finishing positively influenced growth performance due to the compensatory growth of the animals, but no effect of the alpine vegetation could be maintained concerning meat quality characteristics, including the effect on the fatty acid profile. Physical activity, as influenced by the characteristic inclination on seasonal alpine pastures, had limited consequences on growth performances and positively influenced meat quality of suckling beef calves. Meat brightness, juiciness and tenderness were higher in beef calves kept on pastures with a high inclination, with a muscle-dependent response. Muscle contractile metabolism differed according to the topography of the pasture. However, the post mortem proteolytic metabolism was limitedly and inconsistently affected by physical activity. In the system comparison, suckling calves had a reduced physical activity and a better growth performance than weaned calves. Among weaned calves, the mentored calves showed more physical activity but similar growth performances compared with calves kept 12 among themselves. This suggests a positive effect of the presence of mentoring adults. Differences in physical activity were not retrieved in meat quality due to large slaughter weight differences. The present results showed that both the alpine vegetation and the alpine topography influenced meat quality but that a poor growth or a finishing period in barn could also counteract these effects. In the present experiments, satisfactory slaughter performances and meat quality were obtained also without finishing. The key factor to obtain animals ready to slaughter at the end of their stay on seasonal alpine pastures seems to be the balance between the quality of the diet available and the growth stage of the animals.

Item Type:	Doctoral Thesis (Dissertation)
Division/Institute:	School of Agricultural, Forest and Food Sciences HAFL School of Agricultural, Forest and Food Sciences HAFL > Agriculture School of Agricultural, Forest and Food Sciences HAFL > Agriculture > Livestock and Horses
Name:	Gangnat, Isabelle Diane Marie
Subjects:	S Agriculture > SF Animal culture
Language:	English
Submitter:	Isabelle Diane Marie Gangnat
Date Deposited:	04 Jan 2022 11:15
Last Modified:	04 Jan 2022 11:15
ARBOR DOI:	10.24451/arbor.16065
URI:	https://arbor.bfh.ch/id/eprint/16065