Effect of season and location on the crop contents of local and improved scavenging hens in northern Vietnam

An experiment was carried out to determine the effects of season (dry and rainy), location (lowland and highland villages) and breed (local and improved) on the amount and physical and chemical composition of the scavenged feed. This was done by crop content analysis of a total of 192 Ri (local) and 192 Luongphuong (LP, improved) hens at 20 weeks of age. The mean fresh weights of the crop contents were 16.9 and 33.3 g, for the dry and rainy seasons, respectively (p < 0.001), 24.3 and 25.9 g, for the Ri and LP breeds, respectively (p < 0.001), and 25.0 and 25.3 g, for the lowland and highland village, respectively (p > 0.05). The proportions of contents were human food leftovers 38.4% and 24.3%, grains 20.9% and 33.7%, insects and worms 9.6% and 11.2%, and green materials 8.8% and 13.8%, for the dry and rainy seasons, respectively (p < 0.05). The proportion of green materials was higher in the LP hens and highland villages, while the proportion of grains was higher in the Ri hens and lowland village (p < 0.05). The dry matter, crude protein (CP), ether extract (EE), total ash (Ash), calcium (Ca), phosphorus, and metabolizable energy (ME) contents were significantly higher for the rainy season (p < 0.01), and CP, Ash, Ca and ME were higher for the LP hens. The crude fibre content was higher in the dry season, and in the Ri hens and highland village (p < 0.001). The total and essential amino acid concentrations were significantly higher in the rainy season, and in the LP hens (p < 0.05), but were not different between locations (p > 0.05). Nutrient intakes from scavenging were estimated at between 20% and 30% of requirements.