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.
Cassava root silage for crossbred pigs under villag e conditions in Central Vietnam
An on-farm trial in Binh dien and Xuan Loc villages in Central Vietnam compared ensiling of cassava roots (ECR) (chipped by hand or ground by machine) with sun-dried cassava root meal (CRM) with supplements of “A” molasses at levels from zero to 20%. The HCN content of the ground whole cassava root after ensiling for 60 days was reduced from 109 ppm to 64 ppm, while ensiling the chipped root reduced HCN from 111 to 71 ppm. The optimum levels of “A” molasses replacing cassava root (ensiled or dried) in pig diets with protein supply kept constant at 200 g/day was in the range of 15 to 20% for live weight gain and economic purposes. Mean live weight gains were 465 g/pig/day for the cassava root meal diet and 453 g/pig/day for the ensiled cassava root diet each with 20% of “A” molasses. Feed costs/kg gain for the 20% molasses diet with dried and ensiled cassava root were 11% and 27% less than for corresponding diets without molasses. A digestibility trial was carried out using 6 pigs of 72 kg average initial live weight. Three pigs were fed the CRM diet and 3 pigs received the ECR diet. The mean values for apparent digestibilities of dietary nutrients were not significantly different (P>0.05) except that crude fibre appeared to be digested to a greater extent (P = 0.03) in the diet with ensiled cassava root compared with the dried meal (63 vs 34 %).
Hapten inhibition of passive antidextran dextran anaphylaxis in guinea pigs. Role of molecular size in anaphylactogenicity and precipitability of dextran fractions.
High titred antidextran antisera have been raised in rabbits by prolonged immunization with soluble conjugates between isomaltose oligosaccharides or dextran mw 4,400 and bovine serum albumin in complete Freund’s adjuvant. Guinea pigs sensitized with such antisera exhibited anaphylactic shock on i.v. challenge with fractions of hydrolyzed B512 dextran. The severity of anaphylaxis depended on the amount of sensitizing antibody and the dose and molecular size of the challenging dextran fraction. In maximally sensitized animals, fractions of mw 3,600 or larger were anaphylactogenic and smaller molecular size fractions were nonanaphylactogenic. In submaximally sensitized animals, dextran fractions of mw 10,500 or less were foundnonanaphylactogenic. In addition, nonanaphylactogenic dextran fractions produced desensitization, i.e. protection from anaphylaxis due to subsequent or simultaneous injection of more high molecular and anaphylactogenic dextran fractions. When the molar ratio in a mixture of nonanaphylactogenic/anaphylactogenic fractions was about 7.6, protection was complete with reduction of mortality from 100 to 0%. A molar ratio of 1.9, corresponding to a 13-percent by weight admixture of nonanaphylactogenic dextran, still significantly reduced mortality from 100 to 50%. From the ability to form precipitates with antidextrans and to elicit anaphylaxis in sensitized guinea pigs, and from the absence of these properties, the approximate molecular size range of bivalent and monovalent dextran B512 fractions was found to correspond to mw 3,600 and mw 1,430, respectively. The practical applicability of hapten inhibition is discussed.