Envases de polietilentereftalato molidos y su función como sustituto de fibra en la dieta de borregos

the methods used for recycling polyethylene terephthalate (pet) bottles are insufficient and have caused a serious problem of environmental contamination in several countries. an alternative for recycling these bottles is to include them as a source of fiber or inert material in diets for ruminants. with the objective of testing this alternative, 30 lambs (average live weight 23.4 kg; 10 per treatment) were fed diets without (t1 = pet-0) and with 100 (t2=pet-100) and 200 g (t3=pet-200) of ground pet bottles kg-1 dm in substitution of corn stalks. the diets were formulated to cover the nutritional requirements of growing lambs with an average weight gain of 200 g-1. the variables feed intake, weight gain and feed conversion were similar (p>0.05) during the experiment (60 d). the concentration of acetate and ruminal propionate was similar (p>0.05) among treatments, whereas the concentration of butyrate was higher (p≤0.05) in the ruminal fluid of the lambs of the treatment pet-200. the ruminal ph varied from 6.54 to 7.2 without differences (p>0.05) among treatments. the concentration of total bacteria had an interval of 2.84x1010 and 2.97x1010 ml-1 and that of cellulolytic bacteria of 1.32x108 to 1.66x108 ml-1 of ruminal fluid, without differences (p>0.05) among treatments. the concentration of protozoa decreased (p≤0.05) after 45 d in the lambs of treatment pet-200 with respect to treatment pet-0 (1.64 vs 2.49 x 105 ml-1), although these values are normal in ruminants (104 to 106 protozoa ml-1 of ruminal fluid). it is concluded that ground pet bottles can substitute corn stalks as a fiber source, without any negative effect on productive efficiency, ruminal fermentation or concentration of ruminal bacteria and protozoa.