Forage legumes as feed for pigs in smallholder production systems in the North of Lao PDR
Sammanfattning: This thesis sought to characterise and understand existing smallholder pig production systems in the North of Lao PDR and to investigate the role of forage legumes as alternative protein sources for pigs in smallholder production systems. A survey found that there were three main pig rearing systems, free-scavenging, semi-scavenging and confinement (enclosures and pens), in the study areas. These systems were managed differently depending on intensity of crop production, farmer ethnicity and reason for keeping pigs. Farmers fed their pigs mainly rice bran, distiller's waste, maize, cassava and green plant materials. The growth performance was poor, with an average daily gain (ADG) of around 100 g. The reproductive performance of sows was low, with an average litter size of 8.3 piglets and piglet mortality around 50%. Other constraints in smallholder systems were disease outbreaks. An agronomy trial showed that the forage legumes Stylo composite and porcupine joint vetch produced high DM yields, had high contents of crude protein (CP) and had potential to be used as protein sources for pigs in smallholder systems. Harvesting every 45 days produced higher DM yields than other harvesting intervals. The CP content was highest with the shortest harvesting interval, while the opposite was true for the fibre content (CF, ADF and NDF). Growth trials on the CP requirements of growing local Moo Lath pigs showed that final body weight (BW), ADG, feed intake and feed conversion ratio (FCR) did not improve above a dietary CP level of 181 g kg-1 DM for weaner pigs, 132 g kg-1 DM for grower pigs and 111 g kg-1 DM for finisher pigs. Additional growth trials with Moo Lath pigs showed that replacing soybean CP with forage leaf CP reduced DM and energy intake and ADG, but had no effect on FCR. Increasing the replacement of soybean CP with legume leaf CP had a negative linear effect on DM and energy intake, final BW and ADG, and on all carcass traits except lean meat percentage. Supplementing a traditional diet with soybean meal resulted in higher DM and energy intake, lower FCR and higher final BW and ADG.
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