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The study was conducted to determine the effects of chitosan on the concentrations of GH and IGF-I in serum and small intestinal morphological structure of piglets, in order to evaluate the regulating action of chitosan on weaned pig growth through endocrine and intestinal morphological approaches. A total of 180 weaned pigs (35 d of age; 11.56±1.61 kg of body weight) were selected and assigned randomly to 5 dietary treatments, including 1 basal diet (control) and 4 diets with chitosan supplementation (100, 500, 1,000 and 2,000 mg/kg, respectively). Each treatment contained six replicate pens with six pigs per pen. The experiment lasted for 28 d. The results showed that the average body weight gain (BWG) of pigs was improved quadratically by dietary chitosan during the former 14 d and the later 14 d after weaned (p<0.05). Furthermore, dietary supplementation of chitosan tended to quadratically increase the concentration of serum GH on d 14 (p = 0.082) and 28 (p = 0.087). Diets supplemented with increasing levels of chitosan increased quadratically the villus height of jejunum and ileum on d 14 (p = 0.089, p<0.01) and 28 (p = 0.074, p<0.01), meanwhile, chitosan increased quadratically the ratio of villus height to crypt depth in duodenum, jejunum and ileum on d 14 (p<0.05, p = 0.055, p<0.01) and 28 (p<0.01, p<0.01, p<0.01), however, it decreased quadratically crypt depth in ileum on d 14 (p<0.05) and that in duodenum, jejunum and ileum on d 28 (p<0.01, p<0.05, p<0.05). In conclusion, these results indicated that chitosan could quadratically improve growth in weaned pigs, and the underlying mechanism may due to the increase of the serum GH concentration and improvement of the small intestines morphological structure.

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ABSTRACT:The present experiments were conducted to investigate the effects of dietary chitosan on growth performance, nutrient digestibility, and digestive enzyme activities in weaned pigs. A total of 180 weaned pigs (35 days of age, 11.56 ± 1.61 kg of body weight (BW)) were selected and assigned randomly to 5 treatments containing 0, 100, 500, 1000, and 2000 mg chitosan per kg feed, respectively. Each treatment involved six replicate pens and six pigs per pen. On days 14 and 28, all pigs were weighed and six from each treatment (one from each replicate pen) were killed, and the contents of the stomach, jejunum, and rectum were collected and used for determining nutrient digestibility and digestive enzyme activity. The results showed that supplementation of chitosan improved quadratically average daily gain (ADG) (P < 0.05). Moreover, dietary chitosan quadratically (P < 0.05) increased apparent digestibility of crude protein (CP) on days 14 and 28, and quadratically increased apparent digestibility of dry matter (DM) on day 14 and of Ca and P on day 28, whereas decreased (P < 0.05) apparent digestibility of ether extract in comparison with the control diet. In addition, dietary chitosan quadratically increased (P = 0.062) amylase activity of proximal jejunum and decreased (P < 0.05) lipase activity of distal jejunum compared with the control. These data indicated that diets supplemented with increasing levels of chitosan (0, 100, 500, 1000, and 2000 mg chitosan per kg) quadratically improved ADG of weaned pigs. The growth-promoting action was achieved probably by improved digestibility of major nutrients (DM, CP, Ca, and P) and increased amylase activity of jejunum.

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The present experiment was conducted to study the effects of chitosan (CHI) on immune and antioxidative function in beef cattle. A total of 24 fattening Simmental cattle with similar body weight and age were divided randomly into three dietary groups, and the three diets contained 0, 500, and 1000 mg/kg CHI, respectively. The feeding trial lasted for 84 days. It was found that: (1) the addition of CHI in diets improved (P < 0.05) the levels of IgA and interleukin-1, and decreased (P < 0.1) the levels of soluble cluster of differentiation 4 receptor in serum at middle stage except that IgA remained unchanged in 1000 mg/kg CHI group. The levels of IgM and IgA tended to be increased (P < 0.1) by dietary CHI at later stage of the experiment; (2) the addition of 500 mg/kg CHI in diets increased (P < 0.1) total superoxide dismutase activity and decreased (P < 0.05) malondialdehyde content in serum at early and later stages, respectively. In conclusion, these results indicated that addition of 500 mg/kg CHI affected humoral and cellular immune responses, and improved the antioxidative function of beef cattle.

Due to a series of problems, such as drug resistance and tissue residue caused by adding antibiotics to feed, this research aimed to study the effects of Artemisia annua L. aqueous extract (AAE) as an alternative to antibiotics on growth performance and antioxidant capacity of broilers. A total of 240 one-day-old mixed-sex Arbour Acres broilers were randomly allotted into six groups with five replicates of eight birds each. These six diets were formulated by adding 0, 500, 1000, 1500, 2000 mg/kg AAE and 50 mg/kg chlortetracycline (CTC) to the basal diet, respectively. Average daily body weight gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were measured. Total antioxidant capacity (T-AOC), the activity of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the concentrations of malondialdehyde (MDA) were determined, and the relative gene expression in tissues was measured. The polyphenol flavonoid contents and in vitro antioxidative results showed that: the total phenolic and flavonoid contents were 39.58 ± 6.01 mg GAE/g, 7.04 ± 0.55 mg RE/g, respectively. The inclusion of AAE increased ADG, the activities of T-AOC, CAT, SOD and GSH-Px, and the gene expression of antioxidant enzymes, the concentrations of MDA decreased in serum and tissues. In conclusion, AAE can be used as a feed additive due to its capability to improve growth performance, antioxidant function in broilers. Dietary inclusion of 1000-1500 mg/kg AAE can be used as an alternative for antibiotic growth promoter replacement without negative effect on broiler performance. HIGHLIGHTS Artemisia annua L. aqueous extract can promote growth performance and antioxidant function of Broilers. Artemisia annua L. aqueous extract is expected to become the substitute for antibiotics and promote the growth of the body. The optimal dose range of Artemisia annua L. aqueous extract in diet of broilers was 1000-1500 mg/kg.