Feeding oxidized chicken by-product meal impacts digestibility more than performance and oxidative status in nursery pigs

Authors: FRAME, CARL - 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: 2/1/2021
Publication Date: 2/1/2021
Citation: Frame, C.A., Huff-Lonergan, E., Kerr, B.J., Serao, M.R. 2021. Feeding oxidized chicken by-product meal impacts digestibility more than performance and oxidative status in nursery pigs. Journal of Animal Science. 99(2). Article eskab029. https://doi.org/10.1093/jas/skab029.
DOI: https://doi.org/10.1093/jas/skab029

Interpretive Summary: Oxidative stress refers to the imbalance between oxidants and antioxidants in the body which has implications for the health of both animals and humans. From a nutritional aspect, the consumption of heat damaged (i.e., oxidized) proteins or lipids by farm or companion animals could further damage lipids, proteins, or DNA in their body, resulting in an increase of oxidative stress. While protein sources are believed to be relatively stable to oxidation, exposure of processed animal protein meals to additional heat can cause further protein oxidation, which when consumed by an animal, may cause oxidation of lipids, protein, or DNA in their body. The current study was conducted to determine if nursery pigs consuming oxidizing chicken byproduct meal would affect growth performance and induce oxidative stress. Data from this experiment indicated that heating chicken byproduct meal increased carbonyl production in the feed ingredient, and that pigs consuming this oxidized protein had decreased in body weight gain, decreased diet energy and nutrient digestibility, but the consumption of this feedstuff did not induce oxidative stress. 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 proteins in the feedstuff, that short-term feeding appears to depress pig growth due to a decrease in energy and nutrient digestibility, but the decrease in pig growth does not appear to be 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 from the meat industry provide quality proteins in diets for companion animals. These proteins are exposed to extreme temperatures during processing leading to the potential for decreased diet digestibility and subsequent growth performance. While this would impact production efficiency in livestock species, oxidized ingredients in companion animal diets may impact health and longevity. The objective of this study was to determine the extent to which a feedstuff containing oxidized protein and lipid affect diet digestibility, growth performance, and oxidative stress in nursery pigs. Fifty-six male pigs (21 d of age, initial body weight 5.51 ± 0.65) were randomly assigned to 1 of 4 dietary treatments in a 2 × 2 factorial arrangement with two levels of heat and two levels of antioxidant (AOX). Diets were fed for 35 d and growth performance was measured, while total tract digestibility and nitrogen (N) balance was determined during the trial on d 18 to 20. Blood plasma was collected on d 34 and jejunum, colon, and liver tissues were collected on d 35 to analyze for markers of oxidative stress. Average daily feed intake (ADFI) was reduced in pigs fed diets without antioxidants (P = 0.02). Additionally, pigs consuming diets containing heated chicken by-product meal (CBP) had decreased gain:feed (GF; P = 0.02). There was an interaction between heat and AOX (P = 0.02) where heating CBP reduced N digestibility in the presence of an AOX but did not have an impact when AOX was not present. The removal of AOX resulted in reduced GE digestibility (P < 0.01). Dry matter (P < 0.01), ash (P < 0.01), and protein (P < 0.01) digestibility were reduced (P < 0.01) as a result of heating. Furthermore, heating (P =0.01) as well as absence of antioxidant (P =0.01) resulted in reduced digestible energy. No difference was detected in N retention suggesting that oxidation reduces digestibility but has no impact on N utilization. This is supported by the fact that systemic oxidative stress was not consistently affected by heating or AOX inclusion. These results suggest that feeding pigs CBP containing oxidized proteins and lipids did not induce oxidative stress. However, feeding young pigs CBP containing oxidized proteins and lipids did result in reduced energy and nutrient digestibility as well as negatively affected feed efficiency. Because CBP is commonly used in companion animal diets, it is reasonable to revisit their impacts on those species.