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Chemical composition, nylon bag ruminal degradation and the ensiling characteristics of the biomass of 10 short rotation, intensively-cultured hardwood tree species were determined to evaluate their potential feeding value for cattle. Species examined included: ailanthus, aspen, black alder, black locust, birch, elm, green ash, honeylocust, poplar and willow. Dry matter of these species ranged from 27.5 to 31.4% during initial growth, and from 28.2 to 32.3% with regrowth. Species averaged 18.8% in crude protein; black alder, black locust, honeylocust and poplar were over 20%. Only black locust and honeylocust had crude protein percentages higher than 20% with regrowth. Gross energy averaged 4.1 kcal/g and acid detergent fiber (ADF) averaged 28.3%. Ash ranged from 5.2 to 9.0%. Lignin averaged 8.9%, and ranged from 5.5 to 12.2%. With regrowth, the trend was for a decrease in crude protein, ether extract and gross energy, and an increase in dry matter, ash, neutral detergent fiber, ADF and lignin. Ruminal dry matter loss from nylon bags averaged 37.7% with 24 h of incubation. Dry matter loss of black locust and honeylocust were higher (P<.05) than the other species. The ADF loss averaged 15.3% and N loss averaged 41.6%. Black locust and honeylocust were higher (P<.01) in N loss than the other species. With regrowth, all species showed reduced ruminal losses in dry matter, ADF and N. All of the species were adequately ensiled in laboratory silos, with the exception of elm and willow. Based on the data, short rotation, intensively-cultured hardwood tree biomass appears to have a feeding value for cattle.

Growth, nutrient balance, plasma ammonia levels and urinary p-cresol excretion were evaluated in growing pigs fed diets containing various levels of zeolite A or clinoptilolite. In one growth trial, crossbred pigs averaging 25 kg initial body weight were assigned to diets containing no zeolite, .3% zeolite A or .5% clinoptilolite for a 6-wk growing phase trial. Average daily gain (ADG), average daily feed intake (ADF) and feed/gain (F/G) were unaffected by supplementation of either zeolite in the diet, but metabolizable energy (ME) utilization was improved by feeding diets containing either zeolite. A second growth trial utilized the same crossbred pigs, which averaged 65 kg initial body weight, and were assigned to diets containing no zeolite, 1% zeolite A or 5% clinoptilolite for an 8-wk finishing phase trial. Average daily gain, ADF, and ME utilization were unaffected by feeding either zeolite diet, while F/G was increased in pigs fed the diet containing 5% clinoptilolite. In two nutrient balance trials, 16 crossbred pigs averaging 7.5 kg in initial body weight were fed diets containing 0, 1, 2 or 3% zeolite A in one trial and 16 crossbred pigs averaging 7.0 kg initial body weight were fed diets containing 0, 2.5, 5.0 or 7.5% clinoptilolite in a second trial. In both trials, digestible energy, ME, N-corrected ME and ME corrected for N balance and zeolite levels were linearly reduced as increasing amounts of either zeolite were fed. Daily fecal N increased and apparent digestibility of N was linearly reduced by feeding increasing amounts of zeolite A or clinoptilolite. Biological value of protein was improved linearly as higher levels of zeolite A were fed, indicating that there may be some ammonia binding to zeolite A in the gastrointestinal tract. Net protein utilization was reduced by feeding increasing levels of clinoptilolite in the diet. Calcium, P, Mg, Na, K and Fe retentions were linearly reduced by feeding increasing amounts of zeolite A in the diet, while increasing levels of clinoptilolite caused only P retention to be linearly reduced. Both free and conjugated forms of urinary p-cresol were linearly reduced by feeding increasing levels of clinoptilolite. Plasma ammonia levels were reduced at subsequent bleedings after a meal and by increasing levels of clinoptilolite.

Corn in corn-soybean meal starter, grower and finisher diets was replaced at 0, 10, 20 and 30% on a weight basis with standard wheat middlings. Fiber component digestibility studies were conducted with swine initially averaging 12.3 kilograms.Acid detergent fiber and cellulose values of the diets increased only slightly as the percentage of wheat middlings increased. Acid detergent fiber digestibility decreased with increasing wheat middlings with only the starter and finisher diets.Increasing wheat middlings had no effect on serum cholesterol levels; however, serum glucose levels were depressed with 10 to 20% wheat middlings in the diet of male pigs. Apparent absorption of phosphorus and calcium was depressed with added wheat middlings; however, plasma phosphorus and calcium concentrations were not depressed. Plasma zinc concentrations were not significantly different. No significant effect was seen on excreted fecal bile acids with added wheat middlings.

The physical and nutritional characteristics of live and killed brewer's yeast slurries and the possible toxicity of intraruminal administration of loading doses of these by-products were evaluated. Dry-matter (DM) percentages of live brewer's yeast slurry ranged from 10.5 to 29.0, and DM percentages of killed brewer's yeast slurry ranged from 14.6 to 18.5. Total crude protein (N × 6.25) percentages of live and killed yeast slurries (DM basis) were 44.1 and 43.1; ethanol percentages (wet basis) were 6.96 and 1.84, respectively. Phase contrast photomicrographs showed distinct differences in morphology between live and killed yeast cells. Intraruminal administration of loading doses (0, 2.3, 4.5 and 6.8 kg) of live and killed brewer's yeast slurries to bull calves induced clinical intoxication at the 4.5-kg and 6.9-kg dosages of live brewer's yeast slurry. No toxicity was induced either with the killed brewer's yeast or with the 0-kg or 2.3-kg dose levels of live brewer's yeast slurry. The clinical signs and plasma ethanol concentrations suggested ethanol intoxication. Ruminal NH3concentrations increased to over 70 mg/dl with the 4.5-kg and 6.9-kg dosages of live brewer's yeast slurry, but they did not exceed 35 mg/dl with an equivalent dosage of killed brewer's yeast slurry.