Mark East

Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Animal Science


The objective was to evaluate effects of cow breed rotation (Angus-Hereford, Simmental-Hereford, Tarentaise-Hereford), and environment (moderate versus restricted feed intake) on efficiency of beef production. Cows were assigned randomly, by breed, to either a low or moderate pre- (150 and 197 Kcal*Bw-·75 ME) and post (200 and 260 Kcal *BW 75ME) calving intake level. Calves were allowed to nurse two times daily and had ad libitum access to creep feed. Cumulative milk yields were estimated from nonlinear regression based on weigh-suckle-weigh measurements. Data (n = 184 cow-calf pairs) were analyzed by least squares accounting for cow breed, phase of rotation (% Hereford), calf ire type (rotational versus terminal), year, sex, and treatment as fixed effects. Cow weight and condition score were significantly affected by breed rotation (P=.05) and treatment (P=.0001). At weaning, Tarentaise-Hereford calves weighed 7 (P=.07) and 12 (P=.05) kg less than calves from Angus-Hereford and Simmental-Hereford dams, respectively. Calves of moderate-intake cows were 22 kg (P=.0001) heavier at weaning than calve of restricted-intake cows. Low-intake cows were 14% (P=.0001) more efficient in calf production (calf weaning weight/ME intake) and 13% (P=.0001) more efficient in producing milk energy (milk ME/ME intake) but maintained lower weights and body condition than moderate-intake cows. When ME intake was adjusted for difference in cow weight change, low-intake cows were 4% (P=.03) more efficient than moderate intake cows and there was no significant difference in milk efficiency. Cow breed rotation did not significantly affect milk or weaning efficiency, although cows of low percentage Hereford were more efficient for both endpoints than cows of high percentage Hereford. Calves of moderate intake cows had 12 and 8 kg heavier final and carcass weights respectively, than low intake counterparts. However, calves of low intake cows gained more weight per day postweaning. Furthermore, calves of low intake cows were leaner at slaughter and produced more beef per pound of live/carcass weight. Calves of Angus Hereford dams had more marbling than Simmental and Tarentaise Hereford counterparts; however, Angus-Hereford calves had higher percentages of KPH and more fat. The main effect of phase of rotation was non significant for calf carcass traits. The interaction of treatment with cow rotation or phase of rotation was not highly significant for any of the traits evaluated.

Library of Congress Subject Headings

Beef cattle
Beef cattle -- Feed utilization efficiency
Beef cattle -- Cow-calf system



Number of Pages



South Dakota State University