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.
Partitioning nitrogen and amino acids for pregnancy and lactation in swine: a review.
Nitrogen and amino acid requirements for maintenance, maternal growth, mammary growth and products of conception were partitioned on the basis of data from numerous sources. These data were compared with N retention values obtained from balance trials conducted during pregnancy. Carefully conducted N balance trials will yield N retention data that are reasonably comparable with N deposition data determined from tissue analyses. Based on indispensable amino acid (IAA) requirements for maintenance and pregnancy, the IAA were partitioned among maintenance, maternal growth, and products of conception including mammary growth. The nonspecific N requirement also was estimated in these calculations. Results indicate that the pregnancy requirements for total N and nonspecific N could be reduced considerably from present recommendations (NRC, 1988). Nitrogen and IAA requirements for lactation were partitioned between maintenance and milk production. Estimates of total N and nonspecific N that were derived factorially also were substantially less than present recommendations (NRC, 1988).
Spray drying of dairy products: state of the art
Milk is extremely perishable, and yet, for a number of reasons, it has to be preserved for later consumption. The removal of water prevents the growth of micro-organisms and facilitates pres- ervation and storage of milk constituents. Spray drying is one of the most convenient techniques for producing milk powders and for stabilizing milk constituents. Before spray drying, the milk under- goes several processes (such as heat treatment, cream separation, membrane processes, vacuum evap- oration and homogenization). The chemical, physical, technological, nutritional, functional and microbiological properties of final products are influenced by a number of factors such as operating conditions, properties of the dairy products and storage conditions. The aim of this review is to de- scribe the process of spray drying of dairy products and to review the present and recent advance- ments of knowledge on the properties of spray-dried milk products, on modelling and water transfer simulation (drying and rehydration), dairy powders and the spray drying equipment and energy con- sumption.