Digestion and N metabolism in Mong Cai and Large White pigs having free access to sugar cane juice or ensiled cassava root supplemented with duckweed or ensiled cassava leaves
It is envisaged that traits which facilitate more efficient use of byproduct and vegetative feeds will become increasingly important as the role of livestock in farming system changes from that of a specialized producer of animal protein to a more synergistic one of optimizing total resource utilization. The following experiment, which measured digestibility and N retention parameters in Mong Cai and Large White pigs given diets based on local feed resources, is part of a long term study to define more precisely the role of livestock as components of the overall farming system. Four male piglets of Mong Cai breed (mean weight±SD = 8.65±2.3 kg) and four Large White piglets (8.03±1.49 kg) were housed in metabolism cages made of bamboo for four consecutive periods of 10 days during which they received, according to a Latin Square arrangement, dietary combinations of: sugar cane juice or ensiled cassava root in each case with either fresh duckweed or ensiled cassava leaves as the protein supplement. In each 10 day period the first five days were for adaptation to the diet and the last five for determination of digestibility and nitrogen retention. There were no significant interactions among dietary treatments. Apparent digestibility of the nitrogenous fraction was higher (67%) when duckweed, rather than ensiled cassava leaves (59%), was the protein source (P=0.001). Nitrogen retention as a percent of nitrogen intake was high for both protein sources with higher values (P = 0.004) for the duckweed diets (52%) than for diets with ensiled cassava leaves (44%). The efficient use of the dietary nitrogen on all diets implies that both duckweed and ensiled cassava leaves have a good array of the essential amino acids needed for growth, with the advantage slightly in favour of the duckweed because of its superior digestibility.
The Prospect of Duckweed in Pig Nutrition: A Review
The demand for meat and its products has always exceeded supply. To match the ever-increasing demand, more animal products should be produced. Pig production could be a livestock enterprise of choice since pigs grow rapidly and are ready for marketing in a short time. With the escalating costs of feeds, it is worthwhile to use cheaper alternatives such as duckweed. Duckweed has a potential for full utilisation in the nutrition of the different classes of pigs. Researches have been conducted with different classes of pigs. The aim of this review is to consolidate work that has been conducted on duckweed in the nutrition of all classes of pigs, giving recommendations where necessary. In addition, areas requiring research have also been highlighted.
The toxicity of cassava
is a high-carbohydrate, low-protein staple food in many tropical countries. It grows well in tropical climates - as much as 2.5 kcal of food value can be produced from each hec- tare per day, compared with 1.76 kcal for rice. Against this undoubted advantage must be set a major drawback - cassava is poisonous. Although the local populations have developed ways of reducing the toxic effects of cassava, deaths and illnesses can still be attributed to the consumption of this plant. The ill effects of eating cassava can be a result of either the harmful components of the plant (most notably linamarin, a cyanogenic glycoside) or they can be caused by toxins produced by organisms that have infected the food during prepara- tion. Preparation of cassava Both the tuber and the leaves of cassava are eaten, although the tuber is considered the more palatable. There are two major methods for preparing the tuber for food. In the first method, mainly used in rural areas of Nigeria, the tuber is fermented in a large quantity of water and then reduced to a pulp, known as 'akpu'. The akpu is usually wet when prepared and it provides good conditions for the growth of organ- isms, some of which may be toxic. Thus, in addition to the food's inherent toxicity a number of sudden deaths in Nsukka vil- lages in Nigeria have been attributed to the consumption of infected akpu. The second method of preparing cassava tubers, more popular in urban Nigeria, involves fermentation and frying to pro- duce cassava flour or 'garri'. Garri may contain as much as 35 mg of HCN in the average daily consumption of 750 g - almost half the lethal dose of HCN. Con- centrations of this magnitude are said to occur only in the bitter strains of cassava, but unfortunately there is no clear differen- tiation between 'bitter' and 'sweet' strains. As garri is produced in a dry form, the growth of toxic microorganisms is not the problem as it is with akpu. Cassava leaves are also used as food in West Africa, New Guinea and Central Java. As well as the cyanogenic glycosides, the leaves contain hydrogen sulphide. The fresh leaves contain between 491 and 624