Response of crickets to amount of forage in the diet.

Three replicated tests were to define the conditions needed to use house crickets (Acheta domesticus) to evaluate forages. Crickets were placed on various proportion of forage-to-concentrate mixtures to determine the relative proportions best suited for cricket survival, growth, and maturity. The concentrate portion alone was adequate to support nominal cricket performance. Forages used were timothy, alfalfa, and alfalfatimothy (1:1). Forages replaced from 0 to 100%, in increments of 10% of the concentrate portion. A diet of 40% concentrate and 60% roughage was suitable for evaluating growth and survival effects. The 28-day tests were not long enough to evaluate fully the effects of diet on maturity.

Interactions of cadmium with copper, iron, zinc, and manganese in ovine tissues.

Diets containing 0, 5, 15, 30, and 60 ppm of cadmium were fed to male lambs for 191 days to ascertain what effect cadmium might have on the tissue concentrations of copper, zinc, iron, and manganese. The cadmium content of all tissues increased with an increase in dietary cadmium. The iron concentration of the ileum tissue was significantly depressed in the cadmium-treated groups compared with that of the controls. Liver copper, iron, and manganese were significantly depressed and liver zinc significantly increased by varying levels of dietary cadmium. The copper concentrations of the spleen and testicles were significantly decreased by all levels of cadmium while the copper and zinc concentrations of the kidneys were significantly increased in the 30 and 60 mug Cd/g and 15, 30, and 60 mug Cd/g groups, respectively. In general, cadmium had no significant effect on the rumen, abomasal, heart, or lung concentrations of copper, zinc, iron, or manganese.

Effects of cadmium on the growth and uptake of cadmium by microorganisms.

Six species of microorganisms, Escherichia coli, Bacillus cereus, Lactobacillus acidophilus, Staphylococcus aureus, Streptococcus faecalis and Actinomyces niger, were grown under suitable conditions in appropriate media. Cadmium chloride was added to provide 0, 5, 10, 20, 40, and 80 mug of Cd per ml. At 40 and 80 mug of Cd per ml, E. coli and B. cereus grew well and the other species were repressed. Cd uptake patterns differed significantly among the species tested. The significance of these data with respect to Cd in food chains is discussed.

Utilization of nitrogen from soybean meal, casein, zein, and urea by mature sheep.

The utilization of nitrogen contained in soybean meal, casein, zein, and urea was studied in 12 mature wethers. Net microbial synthesis rates during the 6-hour period after feeding corresponded to ruminal ammonia concentrations, suggesting that the ruminal ammonia level in these experiments was a limiting factor in microbiol protein synthesis. Maximum conversion of dietary nitrogen to microbial nitrogen in the rumen during a 24-hour period was estimated to be 62.5, 85.3, 40.9, and 90.1%, respectively, for soybean meal, casein, zein, and urea. Estimated production rates of acetic, propionic, butyric, isovaleric, and valeric acids during the first 6 hours after feeding suggested that zein supported the lowest microbial activity in the rumen, and that urea supplementation resulted in isovaleric and valeric acids production rates equivalent to or greater than rates when the other nitrogen supplements were present in the diet. Daily endogenous urinary and metabolic fecal nitrogen determined by regression analysis utilizing soybean meal as the only nitrogen supplement were 72 mg/kg body weight0.75 and 340 mg/100 g of dry matter intake. Biological values of 84.8, 78.3, 84.3, and 76.4 were obtained for soybean meal, casein, zein, and urea, respectively.