Nouel et al., 1999. Livest. Res. Rural Dev., 11 (1), 111

Two experiments were carried out to evaluate the inclusion of a high proportion of poultry litter in the diet, mixed with citrus pulp or maize meal with or without a flavouring, and its effects on live weight (LW) gain of growing cattle grazing poor quality pastures at the end of the rainy season (E1) and during the dry season (E2). A third experiment (E3) was carried out with rumen fistulated animals to study the effect of these diets on some characteristics of rumen fermentation. In E1, 42 Bos taurus x Bos indicus males of 209 ± 33 kg were used to compare three treatments receiving in pens a mixture of 79% poultry litter, 1% common salt and 20% of citrus pulp (P) or maize meal with 0.05 % of a commercial flavouring (MF) or without it (M). All groups grazed during 16 h paddocks with standing forage of 3.72 ± 1.38 tonnes DM/ha in which Hyparrenia rufa and Trachypogon gracilis predominated. The remaining time the animals were stall-fed the experimental feeds in groups during 84 days. For P, M and MF daily intakes were 1.02, 1.45 and 1.36 kg DM/100 kg LW and LW gains were 0.51, 0.59 and 0.56 kg/day (P>0.05). The same diets were used in E2, but the paddocks were accidentally burned before the trial. The grazing periods were reduced to 8 h and 36 animals of 229 ± 26 kg were used. Standing forage of the regrowth was 1.24 ± 0.42 ton DM/ha. For treatments P, M and MF daily intakes were 2.02, 2.17 and 2.07 kg DM/ 100 kg LW and LW gains were 0.31, 0.53 and 0.48 kg/day (P<0.01). The differences between treatments observed during the dry but not at the end of the rainy season, could be related to the higher mixture intakes in the second trial and their effect on total energy consumption. The same treatments were compared in E3 and an additional treatment (L) with poultry litter as the only supplement was included. A latin square was used with 4 animals of 159 ± 16 kg and periods of 17 days. The trial was carried out during the dry season and intakes per animal were measured, being higher in M and MF than P and L, with values of 3.41, 3.35, 2.18 and 1.25 kg DM/100 kg LW. No differences in rumen ammonia nitrogen concentration were observed, with mean values of 151, 156, 164 and 130 mg/litre, respectively. Three conclusions could be derived from this study. The addition of an energy source to poultry litter in these conditions resulted in more than two-fold consumption increments. The substitution of maize meal by citrus pulp reduced LW gain during the dry season, when high levels of mixture intake were reached. And finally, the addition of a flavouring to diets based mainly on poultry litter and maize meal did not increase intake or LW gain of growing cattle.