Can Supplementation Early in the Feeding Period Help Correct Copper Deficiency and Improve Health Outcomes in Newly Arrived Feeder Calves?

Background

Nutritional strategies to manage bovine respiratory disease (BRD) in newly arrived feedlot calves have received less attention than metaphylaxis, vaccination and stress reduction. The Western and Canadian Cow-Calf Surveillance Networks have found that significant numbers of cows in Western Canada have inadequate levels of copper and selenium or excessive molybdenum (which makes copper deficiency worse). Trace minerals and vitamins are critical for immune function, health and vaccine responses. Plants also grow differently (and dugouts get concentrated) during droughts, which may make matters worse. This may help explain why feedlots suspect that BRD problems are worse in drought years. Previous studies have generally shown that supplementing feedlot calves with chelated or injectable trace minerals can improve health or performance but have never evaluated whether the cattle were deficient or not when they arrived at the feedlot.

Objectives

1. Examine the variation in trace mineral and vitamin status in fall-placed beef calves at feedlot arrival.
2. Compare the timeliness and effectiveness of different micronutrient supplementation strategies on changes in micronutrient status early in the feeding period when the risk of respiratory disease is highest.
3. Examine the effect of different micronutrient supplementation strategies on response to BRD vaccines in feedlot calves.
4. Evaluate the impact of calf micronutrient concentrations early in the feeding period on calf response to BRD vaccination at feedlot arrival.
5. Evaluate the impact of micronutrient concentrations and supplementation strategies on BRD risk, clinical signs and average daily gain (ADG) in calves.

What they will do

These researchers will study whether alternative mineral supplementation strategies on arrival help reduce the risk of BRD or improve calf performance. They will bring 224 auction mart calves from many different herds of origin into the Livestock and Forage Centre of Excellence (LFCE) over two years. An additional 64 calves from the LFCE herd will be challenged with bovine respiratory syncytial virus (BRSV), then mixed with the auction mart calves. The LFCE calves will have been previously vaccinated and boosted against viral BRD pathogens, so they should be protected from serious illness from the BRSV challenge. But they will serve to ensure that the auction mart calves (whose previous vaccination history is unknown) are exposed to a disease challenge in the feedlot. This will help ensure enough calves get sick with BRD to see whether the mineral supplementation strategies have a benefit.

The calves will be processed following standard industry practice and fed in 36-head pens. Half of the pens will be given an inorganic trace mineral supplement in the feed; the other pens will receive a chelated mineral (ZinPro). Within each pen, half of the calves will be given a trace mineral injection (Multimin).

Weight, body temperature and clinical BRD scores will be evaluated on days 1, 13, 27 and 45. Serum trace minerals (Cu, Mb, Se, Zn, Mn and Co) and vitamins (A and E), antibodies against BRD viruses (BVD I & II, IBR, BRSV, PI3 and BCoV) and nasal swabs for BRD viruses will be evaluated on all calves on days 1, 13 and 27. Subsets of calves will be evaluated for cell-mediated immunity and liver trace mineral levels on days 1, 13 and 27.

Implications

Knowing whether on-arrival trace mineral supplementation can help correct common micronutrient deficiencies and reduce BRD early in the feeding period will help Canada’s beef industry strengthen its science-based antimicrobial stewardship strategies.