Ground polyethylene terephthalate bottles and its function as fiber sustitute in diets for lambs

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 d(-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 2.84x10(10) and 2.97x10(10) mL(-1) and that of cellulolytic bacteria of 1.32x10(8) to 1.66 x 10(8) 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 10(5) mL(-1)), although these values are normal in ruminants (10(4) to 10(6) 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.