Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Animal Science

First Advisor

M. P. Hoffman


The objectives of this experiment were to evaluate the use of functional oils (FO) mixture and EssentialTM, with and without ionophores on feedlot performance, carcass characteristics and economic analysis of cattle drylot finishing programs. The FO, natural products composed of cashew nut shell oil and castor oil, have been introduced into the United States because they are thought to offer similar benefits as ionophores without the drawbacks of being synthetic products. A two-trial study was conducted using 120 (322 y 10 kg) Angus and Angus crossbred steer calves in each trial. Calves were weighed and assigned to five treatment groups by weight and color pattern, with four replications and six cattle per replication in each trial. Treatments were: control, no additives (CON); monensin, 223 mg·hd<-l/super>·d<-l/super> (MON); monensin, 223 mg·hd<-l/super>·d<-l/super> + functional oils, 250 mg·kg<-l/super> DMI (MON+FL); functional oils low, 250 mg·kg<-l/super> DMI (FL); and functional oils high, 500 mg·kg<-l/super> DMI (FH). All steers were fed the same diet (0.29 Mcal of NEg/kg DM, 0.41 Mcal of NEm/kg DM) on an ad libitum basis. In the first trial, steers were fed on average for 169 days, and in the second trial, 161 days. The daily DMI was not affected by FO. The MON treatment improved cattle ADG and FE when compared with FL and FH treatments (P < 0.05). The FH treated cattle had a higher percentage of liver abscesses compared with the MON treatment cattle (P < 0.05) and cattle in other treatments. The FH cattle had the highest dressing percentages (DP) among treatments and differed from MON and FL (P < 0.05), but not from CON and MON+FL treatments (P > 0.05). The FH cattle had the largest REA and differed from MON (P < 0.05). However, BF thickness was not different among treatments (P > 0.05). Although, YG for all treatments were YG 2, MON+FL treatment cattle had the best cutability and differed from MON treatment cattle (P < 0.05), but not from CON, FL and FH treatments (P > 0.05). Quality grade was not different (P > 0.05) among treatments. The percentage of Choice and Prime carcasses, however, tended to increase with levels of FO in the diets. The FH cattle had the most Prime grade carcasses and differed from CON and MON+FL treatments (P < 0.05), but not from MON and FL treatments (P > 0.05). Using actual costs and prices, profitability was numerically highest for the MON+FL treatment cattle. The MON treatment cattle tended to have the lowest profitability. Carcass price provided the greatest impact on profitability, followed by feeder price and then corn price when using actual costs and prices. Plus and minus 5% sensitivity analyses for corn, feeder and fed cattle price followed the same trend. When using annual and seasonal price scenarios, profitability favored the FH treatment cattle, presumably a result of their higher percentage of Prime and Choice carcasses. From these results, it is suggested that steer calves provided FO in their diet showed tolerable and similar ADG and FE, and produced carcasses with acceptable and similar YG and QG. The use of FO with an ionophore, such as monensin, in a cattle drylot finishing system is the most profitable compared with other dietary treatments when using actual price; however, when annual and/or seasonal average prices are used, inclusion of FH creates more profitable feeding programs. Thus, the use of FO may provide a viable alternative to ionophores for feedlot cattle.


Copyright Owner

Tsengeg Purevjav



Date Available


File Format


File Size

105 pages