Veterinary session

The Italian ryegrass is a potential possibility for the cattle feeding by ensuring the supply of the so called structural fibre, in increasing the quantity of energy and protein in the forage, by improving the carotene supply of the cows, by reducing the losses and problems of hay-making. Structural fibre is important because rations based on maize silage and 45-50% concentrate result in several metabolic problems (risk of acidosis). Presently the application of the silages from the co-called sweet grasses, due to the lack of digestibility coefficients, is limited by the fact that accurate data on the energy content are not available. Recently estimated values (5.5-6.0 MJ/kg DM) are used for NEl.

The objective of my study was to determine the digestibility coefficients (crude protein, ether extract, crude fibre, nitrogen free extract (NFE)) and degradability (dg) values of the varieties perennial „Bahial” and the annual „Suxyl”, still lacking in the nutrient tables and basing on these data to calculate their true nutrient value (energy, MPE, MPN)

Except ether extract, the nutrient contents of Bahial and Suxyl silages exceeded those of the good quality grass silage, including hemicellulose, cellulose and acid-detergent lignine. Digestibility parameters of Bahial exceeded in each case those of a good quality grass silage. Digestibility parameters of crude protein and NFE in wethers fed Suxyl were higher, that of crude fibre similar, and with ether extract slightly lower, than those of a traditional grass silage. The rumen degradability of the Bahial Italian ryegrass protein is the same as that of a good quality grass silage, but the rumen degradation rate of protein in the Suxyl is higher rendering more ammonia for the bacterial growth in the rumen.

Energy content (NEl) of Bahial and Suxyl ryegrass silage was higher than that of a good quality grass silage, 6.61, 6.16 and 5.51 MJ/kg DM, respectively. Metabolizable protein contents in Bahial and Suxyl silages were higher than those of a good quality grass silage, except MPE.

On the basis of digestibilty and degradability data, energy and protein contents (NEl, MPN, MPE) of ryegrass were calculated. These values may render a great help for the dairy farms using Italian ryegrass silage, enabling them to fit these forages with excellent nutrient content and nutritive value into the daily ration realistically.