Sophie Goethals

High litter sizes in pigs are associated with lower birth weights and increased within‐litter variation, which poses challenges to pig farming. Improving piglet uniformity and survival via genetic selection of terminal boars could be a strategy to enhance these traits. This study evaluated how well estimated breeding values for uniformity and survival of terminal Piétrain sires predict within‐litter uniformity and mortality rates in their crossbred offspring from birth until slaughter. We selected six Piétrain boars with contrasting estimated breeding values for uniformity and survival (3 high vs. 3 low) and mated these with 93 hybrid sows, which produced 1421 liveborn piglets. Moderate correlations were observed between crossbred piglets' within‐litter uniformity and the paternal estimated breeding values ( r = 0.17 to 0.28), indicating that the used estimated breeding values for uniformity and survival of terminal sires have a low predictive value for within‐litter uniformity. Nonetheless, significant associations were found between these estimated breeding values and specific survival‐ and uniformity‐related traits, such as pre‐weaning survival and uniformity of growth, supporting their potential for selection. When analysing piglets' weights over time, low correlations were observed between the coefficient of variation at birth and later in life ( r = 0.05 to 0.24). On the other hand, moderate to high correlations were found between coefficients of variation at weaning and later in life ( r = 0.34 to 0.88), indicating stability of the within‐litter body weight uniformity after weaning. These findings suggest that pre‐ and post‐weaning within‐litter body weight uniformity should be considered as two distinct traits.

Scope: The consumption of red and processed meat, and not white meat, associates with the development of various Western diseases such as colorectal cancer and type 2 diabetes. This work aims at unraveling novel meat‐associated mechanisms that are involved in disease development.Methods and Results: A non‐hypothesis driven strategy of untargeted metabolomics is applied to assess colon tissue from rats (fed a high dose of beef vs. white meat) and from pigs (fed red/processed meat vs. white meat), receiving a realistic human background diet. An increased carnitine metabolism is observed, which is reflected by higher levels of acylcarnitines and 3‐dehydroxycarnitine (rats and pigs) and trimethylamine‐N‐oxide (rats). While 3‐dehydroxycarnitine is higher in HT29 cells, incubated with colonic beef digests, acylcarnitine levels are reduced. This suggests an altered response from colon cancer cell line towards meat‐induced oxidative stress. Moreover, metabolic differences between rat and pigs are observed in N‐glycolylneuraminic acid incorporation, prostaglandin, and fatty acid synthesis.Conclusion: This study demonstrates elevated (acyl)carnitine metabolism in colon tissue of animals that follow a red meat‐based diet, providing mechanistic insights that may aid in explaining the nutritional‐physiological correlation between red/processed meat and Western diseases.

Scope: To improve understanding of the epidemiological link between red and processed meat consumption and chronic diseases, more insight into the formation of metabolites during meat digestion is warranted.Methods and results: Untargeted mass‐spectrometry‐based metabolomics is applied to explore the impact of red and processed meat consumption (compared to chicken), combined with a prudent or Western dietary pattern. A pig feeding study (n = 32), as a sentinel for humans, is conducted in a 2 × 2 factorial design for 4 weeks. The luminal content of the small intestine and colon are collected to determine their metabolic fingerprints. Seventy‐six metabolites (38 in the small intestine, 32 in the colon, and 6 in both intestinal compartments) contributing to the distinct gut metabolic profiles of pigs fed either chicken or red and processed meat are (tentatively) identified. Consumption of red and processed meat results in higher levels of short‐ and medium‐chain acylcarnitines and 3‐dehydroxycarnitine, irrespective of dietary context, whereas long‐chain acylcarnitines and monoacylglycerols are associated with the red and processed Western diet.Conclusion: The identification of red and processed meat–associated gut metabolites in this study contributes to the understanding of meat digestion in a complex but controlled dietary context and its potential health effects.

Red meat has been associated with an increased cardiovascular disease (CVD) risk, possibly through gut microbial-derived trimethylamine-N-oxide (TMAO). However, previous reports are conflicting, and influences from the background diet may modulate the impact of meat consumption. This study investigated the effect of red and white meat intake combined with two different background diets on urinary TMAO concentration and its association with the colon microbiome in addition to apparent hepatic TMAO-related activity. For 4 weeks, 32 pigs were fed chicken or red and processed meat combined with a prudent or western background diet. ¹H NMR-based metabolomics analysis was conducted on urine samples and hepatic Mrna expression of TMAO-related genes determined. Lower urinary TMAO concentrations were observed after intake of red and processed meat when consumed with a prudent compared to a western background diet. In addition, correlation analyses between urinary TMAO concentrations and relative abundance of colon bacterial groups suggested an association between TMAO and specific bacterial taxa. Diet did not affect the hepatic Mrna expression of genes related to TMAO formation. The results suggest that meat-induced TMAO formation is regulated by mechanisms other than alterations at the hepatic gene expression level, possibly involving modulations of the gut microbiota.

Human diets contain a complex mixture of antioxidants and pro-oxidants that contribute to the body’s oxidative status. In this study, 32 pigs were fed chicken versus red & processed meat in the context of a prudent or Western dietary pattern for four weeks, to investigate their oxidative status. Lipid oxidation products (malondialdehyde, 4-hydroxy-2-nonenal and hexanal) were higher in the chicken versus red & processed meat diets (1.7- to 8.3-fold) and subsequent in vitro (1.3- to 1.9-fold) and in vivo (1.4 to 3-fold) digests (P < 0.001), which was presumably related to the higher polyunsaturated fatty acid content in chicken meat and/or the added antioxidants in processed meat. However, diet only had a marginal or no effect on the systemic oxidative status as determined by plasma oxygen radical absorbance capacity, malondialdehyde, glutathione and glutathione peroxidase activity in blood and organs, except for α-tocopherol, which was higher after the consumption of the chicken-Western diet. In conclusion, in contrast to the hypothesis, the consumption of chicken compared to red & processed meat resulted in higher concentrations of lipid oxidation products in the pig intestinal contents, however, this was not reflected in the body’s oxidative status.