One hundred sixty English-cross steers (244 kg, SD=23 kg) were used in each yr of a 2-yr study to determine effects of sorting on performance, carcass characteristics, variability, and profitability in a long yearling system utilizing ranch-source calves. Steers were backgrounded during winter then grazed smooth bromegrass pastures followed by warm season native range prior to entering the feed...

Strategies to control bovine respiratory disease depend on accurate classification of disease risk. An objective method to refine the risk classification of beef calves could be economically beneficial, improve welfare by preventing unexpected disease occurrences, refine and reduce the use of antibiotics in beef production, and facilitate alternative methods of disease control. The objective of...

Angus×Simmental crossbred heifers (n=150) and steers (n=100) were used to evaluate 1 of 5 growing diets: 1) a corn-based growing diet (CRN); 2) a high-fat, high-protein coproduct blend; 3) a high-fat, low-protein coproduct blend; 4) a low-fat, high-protein coproduct blend; and 5) a low-fat, low-protein coproduct blend in a 2×2+1 factorial arrangement. Low-protein and low-fat diets were formulat...

Concerns are growing over the impact of livestock farming on environment and public health. The livestock industry is faced with the double constraint of limiting its use of natural resources and antimicrobials while ensuring its economic sustainability. In this context, reliable methods are needed to evaluate the effect of the prevention of endemic animal diseases on the productivity of livest...

Computer models were used to simulate the feedlot segment of an integrated beef production system. Five breeds, Angus (A), Charolais (C), Hereford (H), Limousin (L), and Simmental (S), in three mating systems, pure-breeding and two- and three-breed rotational crossbreeding, were evaluated for feedlot and carcass performance. Breed data were taken from the literature. Feeder calves (steers and n...

Coccidiosis, caused by protozoa of the genus Eimeria, results in health and economic problems to several classes of livestock. The disease reduces feed consumption, body weight, and feed efficiency and may cause mortality of 24% in some cases (Fitzgerald, 1975). An estimated 77 million young cattle in the United States could be infected by coccidia during the first year of their life. Of these,...

Studies were conducted to evaluate the effect of early weaning steer calves on BW gain, feedlot performance, and carcass characteristics in two herds located in the Northern Great Plains, USA. Steer calves from predominantly Angus Hereford dams were stratified within dam age and calving date (Fort Keogh Livestock and Range Research Laboratory (LARRL), Miles City, MT, USA; n1⁄4354) and randomly ...

The prevalence of bovine respiratory disease (BRD) was assessed in a population of 10,142 beef calves representing nine pure breeds and three composite populations born in 1983 through 1988. Twenty-four percent of the calves experienced at least one episode of respiratory disease during the 1st yr of life; frequencies over the six birth years ranged from 14 to 38%. The timing of respiratory dis...

Recently weaned calves transported to the feedlot are at risk of infection, illness and even death from Histophilus somni and other pathogens associated with bovine respiratory disease (BRD) throughout the feeding period. Gamithromycin is an azalide 15-membered semi-synthetic macrolide antimicrobial that is licensed in the European Union and Canada for therapeutic and preventative treatment of ...

An experiment using 40 Angus or Brahman x Angus preconditioned feeder calves was conducted to evaluate the influence of shipping on cellular immune reactivity. Steers were allotted on the basis of weight and breed to a control or shipped group. Shipped steers were trucked 700 km to a feedlot; control steers remained at the ranch of origin. Total and differential leukocyte counts, phytohemagglut...