Efficacy of fermented carrot by-product diets on blood profiles, immune responses, and faecal characteristics in fattening pigs

Context The agro-industrial by-products are known to be effective in improving the profitability of livestock industry because of the reduction of feed cost due to low supply price and the nutritional characteristics of by-products. Carrots are widely used as food and, thus, produce remarkable amounts of carrot by-products, such as peels and discarded and uncommercialised carrots. Aims This study was conducted to investigate the effect of substituting fermented carrot by-product diets on the blood profiles, immune responses, and faecal characteristics of fattening pigs. Methods Crossed pigs (n = 96, 75.8 kg initial average BW) were divided into eight heads per pen, four diets, and three replications, and were fed an experimental diet for 45 days. Basal diet (C) was substituted with 3% (T1), 6% (T2), and 9% (T3) fermented carrot by-product diets. Key results Although crude protein content in the fermented diet increased at the end of fermentation period (Day 13) compared with the start of the fermentation period (Day 0), the crude fibre content in the fermented diet decreased. Substitution of fermented carrot by-product diet improved the haematic functions of blood due to decreased concentrations of aspartate transaminase, alanine transaminase, and γ-glutamyl transpeptidase, while positively affecting the immunoglobulin G level of serum. Substitution of 6% and 9% fermented carrot by-product diets decreased the emissions of faecal noxious gases such as ammonia, methane, and amine, possibly due to increases in the counts of faecal anaerobic total bacteria, lactic acid bacteria, and yeast. Conclusion Substitution with fermented carrot by-product diets improved the hepatic function of blood and faecal beneficial microflora, while decreasing noxious gas emission and faecal harmful microflora in fattening pigs. Moreover, fermented carrot by-product diets may protect against infection due to increased serum immunoglobulin G (IgG) concentrations of fattening pigs. Implication Substitution with fermented carrot by-product diets is expected to decrease swine odour by enhancing the feeding environment of fattening pigs and carrot by-products are secure feed ingredients or materials in pig diets.