Effects of alpha-lipoic acid on the growth performance and serum biochemical index values of puppies

We investigated the effects of alpha-lipoic acid (α-LA) on the growth performance and health level of puppies. A total of 16 healthy Chinese rural dogs aged 30–45 days were randomly divided into four groups: control group (CG), low-dose group (LDG), middle-dose group (MDG) and high-dose group (HDG). The puppies were fed fresh food supplemented with 0, 0.2, 0.4 and 0.6 g/kg of α-LA, respectively. Average daily feed intake (ADFI), average daily gain (ADG), feed-to-gain ratio (F/G), faecal score, intestinal absorption function and serological indices on days 1, 14 and 28 were determined and analysed. The trial period was 28 days. The following results were obtained: (1) α-LA supplementation at 0.4 and 0.6 g/kg significantly increased the ADFI and ADG of the puppies (P < 0.05) but had no significant effect on the faecal score (P > 0.05); (2) α-LA in the fresh diet significantly increased crude fat (EE) digestibility (P< 0.05) but significantly decreased calcium (Ca) digestibility (P< 0.05), without significant impacts on the digestibility of nutrients such as crude protein (CP) and total phosphorus (P); (3) with increasing α-LA inclusion levels, the content of D-xylose in the blood serum increased, but there was no significant difference among groups (P = 0.097). Adding 0.6 mg/kg α-LA to the fresh diet significantly increased the content of IgG in the serum after 14 and 28 days (P < 0.05). At 28 days, adding 0.4 and 0.6 g/kg α-LA to the fresh diet could significantly increase the contents of albumin (ALB) and total protein (TP) in the blood serum (P < 0.05), and the addition of 0.6 g/kg α-LA could significantly increase the serum levels of IgA and IgG (P < 0.05). The addition of α-LA significantly increased the activities of total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) (P < 0.05), decreased the content of malondialdehyde (MDA) (P < 0.05), decreased the levels of interleukin-1β (IL-1β) and interleukin-6 (IL-6) (P< 0.05) and increased the content of interleukin-10 (IL-10) in the blood serum (P < 0.05). In conclusion, the addition of α-LA at 0.6 g/kg to the fresh diet of puppies can improve the ADFI, ADG, serum immune capacity, antioxidant capacity and anti-inflammatory capacity of puppies.