The use of polyethylene glycol to reduce the anti-nutritional effects of tannins in goats fed woody species

Abstract

The effect of polyethylene glycol (PEG) on intake and digestibility in Sarda goats either fed in metabolic crates or browsing a Mediterranean scrubland, featured by tannin-rich species, was studied. In metabolic cages (Experiment 1) nine dry goats were fed ad libitum with foliage of lentisk ( Pistacia lentiscus L.) supplemented with 200 g per day of a concentrate and either 0, 25 or 50 g per day of PEG. In the scrubland (Experiment 2), with lentisk as main species, 20 goats at the end of lactation, were supplemented with hay and concentrate, receiving 0 or 50 g per day of PEG. In both experiments the PEG did not affect the diet intake. The in vivo CP digestibility of the diet raised from 37% without PEG to 71% with 50 g of PEG in Experiment 1 ( P<0.05) and from 40 to 53% in Experiment 2 ( P<0.01). In the latter experiment the PEG supplemented goats had a higher proportion of lentisk in the diet than the controls ( P<0.05). The milk production and the milk urea content increased as a consequence of PEG supplementation. The PEG showed its capacity to neutralize the tannins allowing a better utilisation of tanniferous species.