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Selectivity of ewes grazing on wheat stubble.

Germán KleeG. 1, Rubén Pulido F. y Jorge Chavarría R.

A study was carried out for 61 days in order to evaluate the selectivity of ewes grazing on wheat stubble with and without a supplement to correct nutritional deficiency. The supplement was offered at a rate of 0.45 kg per ewe per day, composed of: 46.5% oats, 6% fishmeal, 47% rape meal and 0.5 % of minerals. A field of 17.14 hectares of wheat stubble, and 120 Romney Marsh ewes were used. The experimental design was a randomized block, with 60 ewes per treatment. Feces of six ewes per treatment, at the beginning, middle and the end of the experiment were collected in order to make a histological analysis of the relative presence (%) of vegetal species of the stubble consumed by the ewes. Chemical analysis of the stubble was made in order to determine content of total protein (PT), ADF , lignine, ash, N, P, K, Mg, Ca, Mn and Fe. The ewes showed a high selectivity to the species in order to balance the daily ration and great ability to encounter Echium vulgare and Rubus ulmifolius, species with high protein and mineral content. There was no significant difference of selectivity between treatments (P> 0.05), but there was a significant difference between periods (P<0.05). The protein content rate of vegetal species ranged between 4.3 and 22.6 % on a dry matter basis. The following percentages were found in feces: wheat stubble 29.65 % and 26.76 %; Echium 23.62 % and 23.38 %; and Rubus 21.55 % and 28.99% on treatments with and without supplementation, respectively.

Key words: sheep, selectivity, stubble, feeding.

1 Instituto de Investigaciones Agropecuarias, (INIA), Centro Regional de Investigaciones Quilamapu, Casilla 426, Chillán, Chile. E-mail: gklee@inia.cl.

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