An improved grazed class method to estimate species selection and dry matter intake by cows at pasture

Mauro Coppa (1, 2) , Anne A. Farruggia (1) , Philippe Pradel (3) , Giampiero Lombardi (2) , Bruno Martin (1)

1 URH - Unité de Recherches sur les Herbivores
2 Universita di Torino
3 Unité Expérimentale des Monts d'Auvergne

Research has recently focused on pasture species intake by ruminants due to their influence on animal product quality. A field-applicable method which investigates species intake and selection, was tested on two dairy cow grazing systems: continuous grazing on a highly-biodiverse pasture (C) and rotational grazing on a moderately-diverse sward (R). In addition to the grazed class method, which evaluates the percentage of grazed dry matter (DM) per species according to the residual height of the plant grazed, further measurements were introduced to quantify DM consumption and selection index per species. Six and four representative species were studied in the C and R systems respectively. We found an exponential regression between the presence of a species and its contribution to the cattle's daily intake (P<0.01). On the C plot, Festuca nigrescens showed the highest intake (6.2 kg DM/cow d), even if avoided. On the R plot, Taraxacum officinale was intensively consumed (6.1 kg DM/cow d), even cows do not express positive selection for the species, while Poaceae were avoided. Giving details on species consumption, the improved grazed class method may prove especially useful in non-experimental conditions in biodiverse sward to address grazing management to the consumption of species able to give specific characteristics to dairy products.

Mots clés: Species intake; Selection; Dairy cow; Grazed class method; CHAIN FATTY ALCOHOLS; DIET SELECTION; N-ALKANES; MILK-FAT; BOTANICAL COMPOSITION; MOUNTAIN PASTURE; MIXED DIETS; CATTLE; MARKERS

Mots clés: Pasture; ACID-COMPOSITION

Domaines: Sciences du Vivant [q-bio]; Informatique [cs]; Sciences de l'Homme et Société

Mauro Coppa, Anne A. Farruggia, Philippe Pradel, Giampiero Lombardi, Bruno Martin. An improved grazed class method to estimate species selection and dry matter intake by cows at pasture. Italian Journal of Animal Science, 2011, 10 (1), ⟨10.4081/ijas.2011.e13⟩. ⟨hal-02644989⟩