Growing Beef Newsletter
October 2024, Volume 15, Issue 4
Optimizing Performance: The Benefits of Zinc Pre- and Post-Transit
Ally Baumhover, animal science graduate student, Iowa State University
Transportation is an unavoidable aspect of the segmented beef industry, and if poorly managed, can have serious consequences for newly received feedlot cattle. Preconditioning and minimizing transit duration are effective strategies for reducing transit stress. Yet, nutritional management during pre-conditioning - especially mineral supplementation - remains underutilized.
Our research is focused on zinc (Zn) supplementation as it is the second most prevalent trace mineral in the body and supports growth, metabolism, and immune function. Unlike other minerals, Zn is not well-stored in the body and must be constantly supplemented. Its cost-effectiveness and low risk of toxicity makes it an ideal candidate for increased supplementation.
Recently, our group of researchers from Iowa State University (Stephanie Hansen, Dan Thomson, Brock Ortner, Ally Baumhover) and AgriFood Canada (Karen Schwartzkopf-Genswein) set out to explore this question. We assessed the impact of Zn supplementation during preconditioning by feeding cattle either a base diet containing 40 mg Zn/kg dry matter (Zn0) or a diet with an additional 100 mg/kg DM of supplemental Zn (Zn100) for 42 days before transit. Zinc sulfate was used for supplementation. It is important to note that our base diet meets Zn recommendations for beef cattle, so these cattle were not deficient. After 42 days of preconditioning, cattle were transported for either 8 hours (8H) or 18 hours (18H). Upon returning to the feedlot, all cattle received the Zn100 diet to simulate a typical receiving diet for the remainder of the trial.
During the preconditioning period, Zn supplemented cattle surpassed the non-supplemented cattle in all performance parameters. They had greater dry matter intake (DMI), especially in the first two weeks, maintaining this advantage throughout preconditioning (see Figure 1). They also achieved greater average daily gains (ADG) and feed efficiency (gain to feed; G:F), culminating in an additional 13 lbs. of bodyweight (BW) at the end of preconditioning.
Post-transit, Zn-supplemented cattle demonstrated better DMI recovery (as a percentage of pre-transit DMI) when returning to the feedlot in both the 8H and 18H groups, despite all groups receiving the Zn100 diet immediately upon arrival and throughout the rest of the trial.
During the 56 days of the post-transit or receiving period, the previously non-supplemented cattle ‘caught up’ with the performance of the supplemented cattle. The Zn100 cattle had greater DMI on the first week post-transit (week 7), but by week 8 the Zn0 group (previously not supplemented) matched their DMI and generally maintained it for the remainder of the trial (see Figure 1). Additionally, the Zn0 group showed greater feed efficiency (G:F), leading to no difference in BW between the two groups after 28 days on the supplemental Zn diet. By the end of the study, there was no overall difference in DMI, G:F, or BW.
These results indicate that Zn supplementation enhances cattle performance and welfare during the preconditioning and receiving period. Not only does it boost feed intake and growth rates, but also aids in quicker recovery post-transit, particularly after shorter journeys. Given current calf prices, this approach during preconditioning can improve profitability by maximizing growth potential. For feedlot owners, who often have no control over trace mineral status, ensuring adequate zinc levels can enhance cattle performance during the receiving period. By investing in proper trace mineral nutrition, producers can better achieve optimal growth and health for their cattle, leading to greater profitability. Our research on this topic continues, with an upcoming study this fall examining the timing of Zn supplementation, which will be replicated in Canada.
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