Overview of the cattle industry

Carcass weights have increased by about 100 lbs in the last 20 years primarily due to improved genetics but also from production tools such as implants, beta agonists, feed additives and feeding practices (Fig. 2). This increase has obviously reduced the number of cattle needed to produce the same number of pounds of beef for consumption. The decline in number of fed cattle harvested is depicted in Fig. 3.

Fig. 2. Steer carcass weights over time. The data for 2009 are projected to the end of the year.

Fig. 3. US steer and heifer slaughter (commercial). The data for 2009 are projected to the end of the year. Source: USDA.

It is difficult to accurately determine the cost to the industry of bovine respiratory disease (BRD) but it is estimated to be greater than US$500 million per year (NASS Cattle, 2007). Information gathered from our practice indicates that the losses from BRD have fluctuated over the last 18 years with a pattern of 5-year cycles of decreases and increases (Fig. 4). This has occurred despite indications that viral vaccine efficacy has improved during this period. In addition, antimicrobials have been developed for metaphylactic use and have been used aggressively during this same time frame. Seasonality of BRD losses has remained unchanged over the years (Fig. 5), with the fall/winter seasons continuing to be the months with the highest death loss.

Fig. 4. Percent of cattle placed dying from BRD (1991–2008). Source: VRCS, LLC Accounts.

Fig. 5. Average percent of population dying from BRD by month (1990–2008). Source: VRCS, LLC Accounts.

For lightweight cattle, treatment costs have remained virtually unchanged even though drug costs have increased. For heavier cattle, treatment costs have increased during the last 18 years (Fig. 6). We believe that one reason the costs have increased in the heavier weight category is that these cattle are heavier per day of age. Even though the weight for day of age is greater, the immune system is still immature requiring more intervention. Total death loss has been erratic in light cattle but has shown a gradual increase in heavier cattle (Fig. 7).

Fig. 6. Average treatment cost in feeder cattle (1989–2008) in relation to two weight categories (301–650 and 651–900 lbs). Source: VRCS, LLC Accounts.

Fig. 7. Death loss in feeder cattle (1989–2008) in relation to two weight categories (301–650 and 651–900 lbs). Source: VRCS, LLC Accounts.

We need to ask the question whether it is time for the cattle industry to look for alternative ways to reduce death loss instead of continuing to focus on the pathogens? It may be time to focus on the animal's response to the pathogens instead of on the organisms themselves. Work conducted by Aich et al. (Reference Aich, Potter and Griebel2009) demonstrated the effects of stress on cattle, showing that mortality doubled under stress even though the pathogen load was kept constant. An issue I would like to see elucidated is whether or not pathogens such as Mannheimia haemolytica are contagious. If it is not highly contagious then increased focus should be on the immune system and the animal's response to the pathogen. Of certainty is if we continue to do the same thing today and tomorrow as we did yesterday we can expect the same results.