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Total tract digestibility and nitrogen retention of three diets containing different levels of fibre [200, 260 and 320 g/kg neutral detergent fibre (NDF) in dry matter] were determined in three breeds of growing pig at an initial age of approximately 3.5 months. The breeds were local (Mong Cai, MC), F1 crossbred (MC × Yorkshire) and exotic (Landrace × Yorkshire, LY), allocated at random within breed (block) to double 3 × 3 Latin squares. The main fibrous ingredients of the experimental diets were rice bran, cassava residue meal and non-dehulled groundnut cake meal. Digestibility of organic matter (OM), crude protein (CP), NDF, crude fibre, gross energy (GE) and ether extract (EE) decreased as the level of dietary NDF increased (p < 0.001). The r2 values for the relationship between NDF level and digestibility of OM, CP, GE and EE were 83%, 83%, 80% and 82% respectively. On average, an increase in NDF content of 1% unit resulted in a decrease in OM, CP, GE and EE digestibility of 0.67%, 0.75%, 0.50% and 0.42% units respectively. Digestibility of energy and nutrients was the highest for MC and the lowest for LY (p < 0.01), with intermediate values for F1. There was a negative effect of NDF level on nitrogen (N) retained as a proportion of intake (p < 0.05). Nitrogen retention and utilization were significantly higher (p < 0.001) for LY than for MC and F1 pigs. [ABSTRACT FROM AUTHOR]

A cross-sectional survey on the prevalence of diarrhoea in pre-weaning piglets, and on management and feeding systems under farm conditions was carried out in Thua Thien Hue Province. Faecal samples were collected from 63 piglets without, and 90 piglets with diarrhoea to determine the occurrence of Salmonella, Escherichia coli (E. coli) and different E. coli antigens (K88, K99 and 987P). The prevalence of diarrhoea was higher in the rainy season than in the dry season (33% vs 18%) and the results indicated differences in prevalence between areas. Salmonella and E. coli were found to the same extent in faeces from piglets without and with diarrhoea. All E. coli antigens were isolated from piglets without and with diarrhoea. However, the frequency was much higher in piglets suffering from diarrhoea. In piglets with diarrhoea antigen K88 was found in 26% and 20% of the samples, antigen K99 in 37% and 24% of the samples, and antigen 987P in 31% and 32% of the samples collected in the dry and rainy seasons, respectively. Nutrient supply for sows and for piglets was low in comparison with feeding standards, which may be a contributory factor to the high incidence of diarrhoea in piglets. Thus, the nutrition of sows as well as piglets could be important components in the aetiology of the disease and needs to be studied further.

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.

Four diets were formulated with protein from fishmeal (FM), groundnut cake (GC), ensiled sweet potato (Ipomoea batatas L. (Lam.)) leaves (SP) or ensiled sweet potato leaves with lysine (SPL). In experiment 1, 24 crossbred (Large White x Mong Cai) growing pigs were allocated randomly by sex into four groups of six pigs and given one of four diets. Experiment 2 was conducted using 16 crossbred pigs (Large White x Mong Cai) at four farms. On each farm, pigs were allocated to two experimental groups. One group was fed the FM diet and the other group the SPL diet. In experiment 1, the daily live weight gains (DLWG) were significantly higher (p < 0.05) for the FM and SPL treatments (542 and 536 g/day, respectively) than for the GC and SP treatments (464 and 482 g/day, respectively). Feed intake was highest (2.0 kg/day) for the SPL and lowest (1.7 kg/day) for the GC treatment (p < 0.05) and feed conversion ratio (FCR) was highest (3.8 kg/kg gain) for SP and lowest (3.5 kg/kg gain) for FM (p < 0.05). There were no significant differences for carcase measurements among diets (p > 0.05). The feed cost per kg live weight gain was lowest for the SP and SPL diets compared to the FM and GC diets. The results of experiment 2 show that there were no significant differences in feed intake, DLWG and FCR between the two diets (p > 0.05). In conclusion, sweet potato leaves can replace fishmeal and groundnut cake in traditional Vietnamese diets for growing pigs.