Leslie J. Johnson

Tympanic temperature in confined beef cattle exposed to excessive heat load.

Angus crossbred yearling steers (n = 168) were used to evaluate effects on performance and tympanic temperature (TT) of feeding additional potassium and sodium to steers exposed to excessive heat load (maximum daily ambient temperature exceeded 32°C for three consecutive days) during seasonal summer conditions. Steers were assigned one of four treatments: (1) control; (2) potassium supplemented (diet containing 2.10% KHCO3); (3) sodium supplemented (diet containing 1.10% NaCl); or (4) potassium and sodium supplemented (diet containing 2.10% KHCO3 and 1.10% NaCl). Overall, additional KHCO3 at the 2% level or NaCl at the 1% level did not improve performance or heat stress tolerance with these diet formulations. However, the addition of KHCO3 did enhance water intake. Independent of treatment effects, TT of cattle displaying high, moderate, or low levels of stress suggest that cattle that do not adequately cool down at night are prone to achieving greater body temperatures during a subsequent hot day. Cattle that are prone to get hot but can cool at night can keep average tympanic temperatures at or near those of cattle that tend to consistently maintain lower peak and mean body temperatures. In addition, during cooler and moderately hot periods, cattle change TT in a stair-step or incremental pattern, while under hot conditions, average TT of group-fed cattle moves in conjunction with ambient conditions, indicating that thermoregulatory mechanisms are at or near maximum physiological capacity.

Effect of composting on the fate of steroids in beef cattle manure.

In this study, the fate of steroid hormones in beef cattle manure composting is evaluated. The fate of 16 steroids and metabolites was evaluated in composted manure from beef cattle administered growth promotants and from beef cattle with no steroid hormone implants. The fate of estrogens (primary detected as estrone), androgens, progesterone, and the fusarium metabolite and implant α-zearalanol was monitored in manure compost piles. First-order decay rates were calculated for steroid half-lives in compost and ranged from 8 d for androsterone to 69 d for 4-androstenedione. Other steroid concentration data could not be fit to first-order decay models, which may indicate that microbial processes may result in steroid production or synthesis in composting systems. We demonstrate that composting is an effective strategy to remove steroid hormones from manure. Total steroid hormone removal in composted beef cattle manure ranged from 79 to 87%.

Climate Conditions in Bedded Confinement Buildings

Confinement buildings are utilized for finishing cattle to allow more efficient collection of animal waste and to buffer animals against adverse climatic conditions. Environmental data were obtained from a 29 m wide x 318 m long, solid floor, bedded confinement building with the long axis oriented east to west. The south side (front) was approximately 8.5 m high and the north (back) side is approximately 5.0 m high with 3.7 m being open (at the top). The opening was closed to within 1.0 m of the top in the winter. In general, low wind speed and/or decreased air movement associated with the building tends to allow for greater relative humidity (RH) especially at the front of the building (south facing) in the summer and winter. The use of the buildings did not lessen heat stress in the summer, as measured by the temperature humidity index (THI) but acted as a shade to decrease the solar heat load on the animal. During the summer season, temperatures were generally greatest at the front of the building. However, in the winter, 2 to 4oC greater temperatures were maintained in the building when compared to outside conditions, by decreasing air flow through the building and from heat generated by the cattle. Bedded barn facilities appear to be useful for buffering cattle against the adverse effects of the environment under hot and cold conditions even though less airflow and greater RH can be found inside the barn when compared to outside conditions.