Recent research has given much attention to the use of phytogenic additives in the diets of weaning piglets. Interestingly, however, researchers turned their focus to finishing pigs in a recent study, demonstrating the potential of dietary nano-curcumin as an effective feed additive for improving their performance and health status.
Research studies emphasise the use of phytogenic compounds in the form of nanocapsules as most phytogenic materials are poorly bioavailable in biological systems. Curcumin is a polyphenolic bioactive compound extracted from the turmeric plant, Curcuma longa, which has phytotherapeutic potential owing to its antimicrobial, antioxidant, anti-inflammatory, and immunostimulatory properties.
To increase its solubility and bioavailability, nano-formulation of native curcumin is a better option in animal diets. Previous studies have shown the encapsulation of phytogenic compounds to enhance intracellular uptake and improve delivery in the target organs through surface area modification of the phytogenics.
In this study, researchers investigated the effects of nano-curcumin nanospheres on growth performance, serum biochemistry, meat quality, and gut health of finishing pigs. For the duration of the study (40 days), crossbred pigs with an average initial body weight of 73.8 kg were assigned one of 3 diets:
The results showed a positive outcome of dietary nano-curcumin through enhanced growth and feed utilisation (Table 1). Supplementation with nano-curcumin led to significant improvements in average daily gain (ADG) and feed conversion ratio (FCR), which were more pronounced as the dosage increased. The growth improvements were attributed to the observed improvements in gut health that are described below.
The neck and longissimus dorsi muscle nutrient composition was similar between the curcumin and the control group. Nano-curcumin improved the lightness, redness, and yellowness of both neck muscle and longissimus muscle. The carcass weight and backfat thickness of pigs fed the higher NC supplemented (2.0 ml/kg diet) diet were higher than those of the control and low concentration NC groups, which endorsed the beneficial effects of nano-curcumin supplementation on weight gain, following the slaughtering of pigs.
The grading percentage (1+) of pork meat also increased with dietary supplementation of NC, which was attributed to the improvement in meat quality in pigs fed nano-curcumin-incorporated diets; higher-class meat grade (1+) and lower-class meat grade (2) was 37% and 20% for the 2.0 ml/kg NC diet compared to the control diet that had 23% and 40%, respectively.
Histological measures on the intestine, the modulation of microbiota, and intestinal immune response all determine gut health and help establish the health status of pigs.
Gut morphology can serve as an important tool to evaluate the absorption and utilisation of a feed additive in the intestine, which ultimately affects the growth and health status of animals. Abnormalities or changes in GIT, especially in the small intestine as the major site for nutrient absorption, may influence the overall growth of the animals. In the current study, pigs fed the NC-supplemented diets had remarkably enhanced villus length, crypt depth, and goblet cell number in the jejunal part of the intestine, which was attributed to the higher surface area of the intestine for absorption of curcumin. The number of goblet cells per villus was significantly higher (4% and 5% higher) in pigs fed the NC-1 diet and NC-2 diet, respectively, compared to pigs fed the control diet.
Intestinal bacteria content
Researchers reported the effects of dietary supplementation with nano-curcumin on the pathogenic and beneficial bacterial contents in faecal and intestinal samples collected from finishing pigs at the end of the experimental period. The intestinal (jejunum) bacteria Lactobacillus spp., E. coli and Salmonella spp. were not altered by nano-curcumin; however, the supplementation of both levels of nano-curcumin resulted in lower faecal E. coli and Lactobacillus spp. contents than was observed with the control diet.
Intestinal immune response
Immunohistochemistry of jejunum sections of the intestine of finishing pigs demonstrated that the expression of the pro-inflammatory cytokine, tumour necrosis factor (TNF-α) is reduced in the NC-supplemented diet compared to the control diet group. On the other hand, the expression of IgA and CD3 proteins was increased in the jejunal intestine of pigs fed NC diets, which was attributed to the enhancement of gut immunity and intestinal permeability of curcumin in finishing pigs.
The GIT of animals is composed of the outermost cellular barrier and the innermost immune functional barrier systems. For the intestinal epithelial cell barrier functions, tight junction proteins such as claudins, occludin and zona occludin-1 are key proteins, which create a physiological and immunological barrier in the intestine. A similar study conducted in piglets found that dietary supplementation of curcumin improves intestinal permeability by increasing the mRNA expression of the tight junction proteins occludin, claudin-1 and zonula occludin-1.
Serological information of blood is an important tool for ascertaining the health status of animals. In this study, glutamic-pyruvic transaminase, glutamic-oxaloacetic transaminase, triglycerides, and cholesterol levels decreased significantly at the end of the finishing stage in pigs fed nano-curcumin-incorporated diets, which was attributed to the immunomodulation effects of dietary curcumin in improving the health condition of pigs.
Another benefit of supplementing nano-curcumin was a reduction in the emission of ammonia; both curcumin levels led to a 65% reduction in faecal ammonia gas emissions compared to the unsupplemented diet.
In conclusion, the results of the present study show that dietary supplementation with nano-curcumin can enhance growth performance, serological indices, immunity, meat quality, and gut health, as well as reduce the emission of ammonia in finishing pigs.
*This article is based on the publication by Mohammad Moniruzzaman, Dahye Kim, Hyunsoo Kim, Nayoung Kim, Sungyeon Chin, Adhimoolam Karthikeyan, Kyuhyuk Han and Taesun Min. 2023. Evaluation of dietary curcumin nanospheres as phytobiotics on growth performance, serum biochemistry, nutritional composition, meat quality, gastrointestinal health, and faecal condition of finishing pigs. Frontiers in Veterinary Science, 10:1127309.