Nitrogen Balance in Goats Fed Flemingia (Flemingia Macrophylla) and Jackfruit (Artocarpus Heterophyllus) Foliage Based Diets and Effect of a Daily Supplementation of Polyethylene Glycol (PEG) on Intake and Digestion

Diets with foliage of Flemingia (Flemingia macrophylla) or Jackfruit (Artocapus heterophyllus were fed to goats with the objective to study nitrogen (N) balance and effect of a daily supplementation of polyethylene glycol (PEG) on intake and digestion. In experiment 1, three male Alpine${\times}$Jamnapary goats with initial weights varying from 26.9 to 27.7 kg were used in a $3{\times}3$ Latin square design in the dry season. Three Alpine${\times}$Bachthao crosses, 15.3-16.7 kg, were used in the same design in the wet season. The three diets were based on chopped whole sugar cane complemented with the two green foliages, Jackfruit and Flemingia, or soybean meal (SBM). The level of dry matter (DM) offered was 4% of body weight (BW), 2.7% as foliage and 1.3% as chopped whole sugar cane. The amount of SBM offered was calculated to give the same amount of crude protein (CP) as the foliages. Each experimental period lasted 32 days (14 days for adaptation, 7 days for collection and 10 days for rest). Feed intake, apparent digestibility of DM, organic matter (OM), CP, neutral detergent fiber (NDF) and acid detergent fiber (ADF) and retained nitrogen (N) were measured by total faecal and urine collection. In experiment 2, four male goats (Alpine${\times}$Jamnapary) with initial weights from 17.1 to 23.1 kg were used in a $4{\times}4$ Latin square design. The four treatments were Jackfruit or Flemingia with or without addition of PEG, which was fed at a level of 5 g/goat and day by mixing with a small amount of rice bran. Each experimental period lasted 15 days (8 days for adaptation, 7 days for collection). Measurements were done as in experiment 1. The DM digestibility was highest (65.9-74.3%) for goats fed the SBM diet in both the dry and wet season. The DM digestibility of goats fed the Jackfruit and the Flemingia diets was similar in both the dry (58.6-59.2% respectively) and the wet season (53.9-56.1% respectively). The CP digestibility was highest (73.0-73.6%) for the SBM diet followed by the Jackfruit diet (47.0-38.5%) and was lowest (36.8-30.0%) for the Flemingia diet in both dry and wet seasons, respectively. The NDF digestibility was low for both the Jackfruit (36.4%) and Flemingia (38.0%) diets in the wet season. All diets resulted in a positive N balance. The N retention was highest (0.465-0.604 g/kg $W^{0.75}$) in the SBM diets and lowest (0.012-0.250 g/kg $W^{0.75}$) in the Flemingia diet. Addition of PEG had no effect on feed intake for any of the diets. PEG added in the Flemingia diet had a positive effect only on NDF digestibility, but the digestibility of the Jackfruit diet was significantly increased. Supplementation with PEG reduced digestibility and N retention of Flemingia, possibly because of the low tannin level, but increased digestibility and N retention for Jackfruit foliage.