Donald E. Johnson

Estimates of animal methane emissions

The enteric methane emissions into the atmospheric annually from domestic animals total about 77 Tg. Another 10 to 14 Tg are likely released from animal manure disposal systems. About 95% of global animal enteric methane is from ruminants, a consequence of their large populations, body size and appetites combined with the extensive degree of anaerobic microbial fermentation occurring in their gut. Accurate methane estimates are particularly sensitive to cattle and buffalo census numbers and estimated diet consumption. Since consumption is largely unknown and must be predicted, accuracy is limited often by the information required, i.e., distribution of animals by class, weight and productivity. Fraction of the diet lost as enteric methane mostly falls into the range of 5.5–6.5% of gross energy intake for the worlds cattle, sheep and goats. Manure methane emissions are heavily influenced by fraction of disposal by anaerobic lagoon. Non-ruminants, i.e., swine, become major contributors to these emissions.

Metabolic rate, organ mass, and mitochondrial proton leak variations in lean and obese rats

The purpose of this study was to determine if differences in metabolic rate between lean and obese strains of rats were associated with differences in proton leak across the inner mitochondrial membrane. Metabolic rates were determined for each of five obese Zucker, Sprague-Dawley, and Fisher 344 rats and three lean Zucker rats by 24-hour indirect respiration calorimetry measurements. Feed intakes were different (P < 0.05) among all strains, with the obese Zucker rats having the greatest intakes. Adjusted to a common dietary intake, the obese Zucker rats had at least 21% lower heat productions than the lean strains of rats. Following the calorimetry measurements, the rats were sacrificed, internal organs were removed and weighed and mitochondria were isolated from the liver. Internal organs composed a larger proportion of lean body mass in obese compared to lean rats. Respiration rates and membrane potentials of the mitochondria were then determined. Proton leak kinetics were visualized by plotting proton leak (calculated from respiration rate) against membrane potential. The lean rats had a 2-3-fold higher proton leak rate than the obese Zucker rats at the same membrane potential. A low mitochondrial proton leak rate may explain part of the abnormal heat productions and bioenergetic efficiencies in the obese Zucker rat.

Equine Industries Manure Disposal Practices, Variations and Magnitude

ABSTRACT The American Horse Council reported that there are 5.2 million horses in the U.S. with 192,000 in the state of Colorado. Each year one horse produces about 10 tons of manure. The objective of this survey was to look at the manure handling systems of 1.5% of Colorado horse ranches, estimate the possible methane production from horse manure, and examine the potential for pollution as an effect of the manure handling practices. The survey consisted of 2960 horses from 24 ranches. The survey indicated there are two management systems for horses, pasture-range (55.6%) and confinement (44.4%). Within the confinement systems, there are two manure handling systems; compost (decomposing stock pilings) (31.6%) and fresh spread (12.7%). Estimated total manure methane production for the state of Colorado is 3320 tons/yr; and for the U.S. horse population 89,900 tons/yr.