Issue Date
1987-09-01Keywords
intakefree range husbandry
urine
digestible energy
liveweight gain
energy balance
feces
nitrogen
heifers
metabolizable energy
Colorado
Metadata
Show full item recordCitation
Senft, R. L., Stillwell, M. A., & Rittenhouse, L. R. (1987). Nitrogen and energy budgets of free-roaming cattle. Journal of Range Management, 40(5), 421-424.Publisher
Society for Range ManagementJournal
Journal of Range ManagementDOI
10.2307/3899602Additional Links
https://rangelands.org/Abstract
Energy and nitrogen (N) budgets of free-roaming yearling heifers were quantified. Energy and N retention were estimated from liveweight gains. Intake and excretion of N and energy were measured directly. Dry matter intake per unit metabolic body weight (MBW = Bwkg.75) varied seasonally, peaking in late growing season. Fecal dry matter output, which was related to dry matter intake, also peaked late in the growing season. Urine volume, however, peaked early in the growing season. Urinary N excretion per MBW was correlated with dietary N concentration (r = .79). Fecal N excretion per MBW was relatively constant while fecal N concentration varied. Partitioning of N losses between feces and urine varied seasonally, with 54% excreted in urine during the growing season (April through October) and 45% in urine during the dormant season (November through March). On a year-round basis, 8% of ingested N was incorporated into body tissue. Fecal energy excretion trend followed that of gross energy intake. Digestible energy intake per MBW was relatively high throughout the growing season and steadily declined after onset of the dormant season. Urinary energy output was closely related to urinary N output and peaked early in the growing season. Metabolizable energy (ME) followed dynamics similar to those of digestible energy. Net energy for liveweight gain accounted for about 8% of gross energy intake on a year-round basis. ME and crude protein intake were above maintenance requirements during the growing season, but were inadequate during the dormant season. ME intake apparently limited growth early in the growing season; protein intake was limiting late in the growing season.Type
textArticle
Language
enISSN
0022-409Xae974a485f413a2113503eed53cd6c53
10.2307/3899602