|Mader, T - UNIV NEBRASKA|
|Dahlquist, J - UNIV OF ILLINOIS|
|Hahn, G - MARC (COLLABORATOR)|
|Gaughan, J - UNIV QUEENSLAND|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 16, 1999
Publication Date: N/A
Interpretive Summary: Three summer trials were conducted to compare the performance of feedlot cattle in facilities with or without shade and with or without shelterbelt wind barriers for wintertime protection. Results indicate shade improves natural summertime performance of cattle fed in pens having shelterbelts which restrict natural airflow. Shade in pens without shelterbelts improves performance when cattle have not yet acclimatized to hot conditions and/or are nearing market weight and condition. However, benefits of shade may be short-term and not observed every summer.
Technical Abstract: In each of three summertime trials conducted over consecutive years, Bos taurus steers were blocked by weight and randomly allotted to one of sixteen pens in a 2 x 2 factorial arrangement of treatments (facilities with or without wind barriers and with or without shade). Corn based diets (1.43 Mcal/kg, NEg) were fed. Mean starting date and days on feed were June e26 and 79, respectively. Each of four 6.1 m x 6.1 m shade structures were placed over the center of the mound providing shade (2.65 sq. m/steer) for two pens. For cattle fed in facilities with wind barriers, airflow was reduced from the north and northwest by a 20 m wide shelterbelt. Greater (P<.10) gains and lower dry matter intake (DMI) gain were obtained by providing shade for cattle fed in open areas only during the early (0-28 d) part of the summer. For cattle fed in pens with wind barriers, shade increased 0-56 d (P<.05) gain and decreased 0-28 d (P<.05) and 0-56 d (P<.10), and 57-final (P<.10) DMI/gain. The shade response in the protecte area appeared to be greater the first year compared to subsequent years, partially explained by differences in weather patterns among years and possibly by a greater fat thickness at finish in the first than in the second and third years. Correlations between blackglobe-humidity index (BGHI) and DMI tended to be greater during the early portion of the trial (0 to 28 d) vs over the entire trial. Correlations between the difference in BGHI under shade vs no shade and % shade use had the greatest magnitude (+/-) and were significant only in the first 28 d vs over the entire feeding period. Results of this study suggest shade improves performance of cattle fed in protected area, when the animals have not become acclimatized to hot conditions and/or have a higher level of body condition.