Impact of dietary oxidized protein on oxidative status and performance in growing pigs

Authors: FRAME, CARL - Iowa State University; JOHNSON, ERIKA - Iowa State University; KILBURN, LOGAN - Iowa State University; HUFF-LONERGAN, ELISABETH - Iowa State University; Kerr, Brian; SERAO, MARIANA - Iowa State University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2020
Publication Date: 5/1/2020
Citation: Frame, C.A., Johnson, E., Kilburn, L., Huff-Lonergan, E., Kerr, B.J., Serao, M.R. 2020. Impact of dietary oxidized protein on oxidative status and performance in growing pigs. Journal of Animal Science. 98(5). https://doi.org/10.1093/jas/skaa097.
DOI: https://doi.org/10.1093/jas/skaa097

Interpretive Summary: Oxidative stress is defined as an imbalance between pro-oxidants and antioxidants and has implications for the health of both animals and humans. From a nutritional aspect, the consumption of oxidized products by farm or companion animals could further damage lipids, proteins, or DNA, resulting in an increase of oxidative stress. While protein sources are believed to be relatively stable to oxidation, exposure of rendered animal proteins to heat can cause oxidation and create reactive oxygen species, which when consumed, may cause oxidation of lipids, protein, or DNA in the body. The current study was conducted to determine if growing pigs consuming oxidizing spray dried bovine plasma would affect growth performance and induce oxidative stress. Data from this experiment indicated that heating spray dried bovine plasma did result in carbonyl production in the feed ingredient, and that pigs consuming this oxidized protein had slight decreased in body weight gain, decreased diet digestibility, but did not induce oxidative stress in pigs consuming this product. This information is important for rendering companies, universities, feed companies, and pig production facilities that while heating of protein feedstuffs may cause some oxidation of the feedstuff, that short-term feeding appears to depress pig growth due to a decrease in digestibility, and not due to an increase in oxidative stress; each of which is important in providing a basis from which to assess an oxidized protein’s feeding and economic value.

Technical Abstract: Rendered products of the meat industry can provide economical quality sources of proteins to the animal and feed industry. Similar to lipids, rendered proteins are susceptible to oxidation, yet the stability of these proteins is unclear. In addition, interest in understanding how oxidative stress can impact efficiency in production animals is increasing. Recent studies have shown that consumption of oxidized lipids have led to a change in oxidative status of the animal, as well as decreases in production efficiency. To date, little is known on how consumption of oxidized proteins will impact oxidative status and growth performance. The objectives of this study were to determine if feeding oxidized protein to growing pigs would: 1) impact growth performance, and 2) induce oxidative stress. Thirty pigs (42 day old initial body weight (BW; 12.49 kg) were randomly assigned to 1 of 3 dietary treatments with increasing levels of oxidized protein. Spray dried bovine plasma was used as the protein source and was either unheated upon arrival, heated at 45C for 3 days, or heated at 100C for 3 days. The experiment lasted 19 days for collection of growth performance data and collection of blood plasma, jejunum, colon, and liver tissues to analyze for markers of oxidative stress (e.g., protein oxidation, lipid oxidation, DNA damage, and glutathione peroxidase activity). Average daily gain (ADG; P < 0.01) and average daily feed intake (ADFI; P < 0.01) had a positive linear relation with increased protein oxidation, but there was no effect on gain to feed ratio (GF). Furthermore, protein (P = 0.03) and fat (P < 0.01) digestibility was reduced with increase protein oxidation in the diet. Crypt depth showed a positive linear relation with dietary protein oxidation levels (P = 0.02). A trend was observed in liver samples where pigs fed the plasma heated to 45C had increased lipid oxidation compared to pigs fed the plasma either unheated or heated to 100C (P = 0.09), while DNA damage in the jejunum tended to have a linear relation with dietary protein oxidation level (P = 0.07). Even though results suggest dietary oxidized protein did not induce oxidative stress, differences in performance, gut morphology, and digestibility are likely a result of reduced protein availability due to structural changes of proteins and oxidative modifications to amino acids.