EFFECT OF AGE OF STAR GRASS (CYNODON-NLEMFUENSIS) ON THE DIGESTIBILITY AND CONSUMPTION OF PIG DIETS

Fifty two hybrid pigs of a commercial line of approximately 93 kg live weight were used in two experiments to evaluate the effect of regrowth age of star grass (Cynodon nlemfuensis) on the digestibility and cons umption of pig diets. In experiment 1, 4 male pigs were used to evalua te the digestibility of star grass (SG) of 3 and 9 weeks of age. Treat ments of SG of 3 weeks/9 weeks were as follows: A) 100/0; B) 67/33; C) 33/67 and D) 0/100. A 4 x 4 Latin square design was used. There were no significant differences (P > 0.05) in dry matter (DM) digestibility , crude protein (CP), crude fibre (CF), organic matter (OM) and gross energy (GE) of the treatments. In experiment 2, SG consumption of 3 an d 9 weeks were evaluated in four inclusion levels (0, 12, 24 and 36%), in a random block design with a 2 x 4 factorial arrangement. The DM, OM and CP consumption showed a trend to decrease as the pasture level (P < 0.05) was increased; the CF consumption in both forages presented a quadratic response (P < 0.05). There was no effect of pasture I age (P > 0.05) and of the pasture age x inclusion level interaction (P > 0.05). In a third experiment the water retention capacity of the pastu res used in experiment 1 was measured in two hydration times (2 and 4 hours). There was a trend toward decreasing the water retention as SG age (P < 0.05). increased at both times. Results suggest that there wa s no effect of age of the SG used on digestibility and consumption and that probably its hygroscopic capacity could influence these results.