Livestock production on California’s annual rangelands has adapted to the seasonality of rangeland forage dominated by annual grasses and forbs growing in a Mediterranean-type climate. Rangeland managers have learned to balance seasonal forage availability and quality with the changing physiological needs of their animals by feeding them hay and other supplements and by transporting them to other forage sources, including other vegetation types in cooler climates.

 This publication gives an overview of seasonal forage sources, nutrient requirements of grazing animals, seasonal forage quality, seasonal animal performance, supplemental feeding, water needs, livestock production systems, and animal health issues. 

Background: The use of antimicrobials in the livestock industry has been a topic of increasing concern in the last  few years. Calf scours is one of the main causes of mortality among calves younger than 1 month and affects the development of the animal, representing severe economic losses to the producers. The causes of the disease include a variety of viral, bacterial and protozoal pathogens, and other non-infectious causes. The treatment efficacy, in particular of antimicrobial therapy, depends on the type of infection. Blanket antimicrobial treatment for calf scours without identification of the pathogen may contribute to antimicrobial resistance. In this review we explore the available literature for evidence of effective methods to prevent calf scours in cow-calf operations in California through the use of vaccination.

Objectives:  The objective of this scoping review is to examine and describe the existing literature on vaccination for the prevention of calf scours that might reduce the incidence of calf scours by different causes, and therefore reduce the use of antimicrobials due to calf scours.

Design: Primary research on vaccination for pathogens that cause calf scours will be considered for inclusion, such as studies conducted in pre-weaned calves that report the efficacy of vaccines for the prevention of calf scours. The process for selection and inclusion of the studies will be reported in a flow chart according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). The results will be summarized in tables and charts describing study types, interventions and outcomes.

Monensin is known to improve feed efficiency in cattle. At higher doses, however, monensin reduces the palatability of mineral supplements, which may reduce consumption of essential minerals such as selenium. The main objective of this study was to compare weight gain, while evaluating the impact on blood selenium concentrations, among treatment and control groups of stocker calves supplemented with a self-fed mineral supplement designed to deliver different amounts of monensin, while the control group received the same mineral without monensin. A secondary objective was to compare the presence of pathogenic and total coccidia oocysts. At study end, all monensin treatment groups weighed more than the control group but were not different from each other. No effect was detected on coccidia oocysts. In sum, there is a production gain from providing monensin in a mineral supplement to weaned calves on pasture. However, too high a dose may lead to insufficient trace mineral consumption. This is a concern in areas where forage is deficient in these nutrients.