Resumo

MENJURA, R. M.; PENUELA, L. M.  e  CASTANEDA, R. D.. Influence of density of Leucaena trees on milk production and urea nitrogen in F1 Gyr x Holstein cows. Rev. Med. Vet. Zoot. [online]. 2018, vol.65, n.1, pp.36-. ISSN 0120-2952.  https://doi.org/10.15446/rfmvz.v65n1.72022.

The objective of this research was to evaluate the chemical composition, selectivity, partial intake, milk production and concentration of urea nitrogen in blood and milk in F1 (Gyr x Holstein) dairy cows on silvopastoral systems with different densities of Leucaena leucocephala trees. The study was carried out in the Chaco Farm, Tolima (Colombia). The treatments were: T1: Cynodon nlemfluensis pasture without trees; T2: C. nlemfluensis + 1264 trees/ha of L. leucocephala; T3: C. nlemfluensis + 4255 trees/ha of L. leucocephala and T4: C. nlemfluensis + 9899 trees/ha of L. leucocephala. Four experimental periods of 32 days each were evaluated and 16 F1 (Gyr x Holstein) cows were used. Differences (P < 0.05) were observed in the dry matter content between C. nlemfluensis and L. leucocephala. Further, there was high selectivity of the cows for the grass (P < 0.05). Dry matter intake decreased with the increase in density of L. leucocephala trees in period 3 only (P < 0.05). As the density of L. leucocephala trees increased, the values of urea nitrogen in blood and milk increased (P < 0.05). Milk production was not different among any of the treatments. It is concluded that F1 (Gyr X Holstein) cows in silvopastoral systems show high selectivity and partial intake of grass, and higher levels of blood and milk urea nitrogen.

Palavras-chave : Cynodon nlemfluensis; Leucaena leucocephala; silvopastoral system; tropical dry forest..

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