Effects of montmorillonite clay on growth performance, nutrient digestibility, vulva size, faecal microflora, and oxidative stress in weaning gilts challenged with zearalenone

Two experiments were conducted to evaluate the effects of montmorillonite clay (MC) on performance and nutrient digestibility of pigs challenged with zearalenone (ZEA). In experiment 1, 144 gilts (10.07 ± 0.87 kg) were assigned to 1 of 8 treatments in 2 × 4 factorial randomized complete block design for a 28 d trial (6 pigs/pen, 3 pens/treatment). Factors included (1) ZEA levels (0, 0.2, 0.4, or 0.8 mg ZEA/kg) and (2) MC addition [Clay to ZEA ratio maintained at 2500:1 (w:w)]. These diets included: (1) control, (2) control + 2 g MC/kg, (3) control + 0.2 mg ZEA/kg, (4) control + 0.2 mg ZEA/kg + 0.5 g MC/kg, (5) control + 0.4 mg ZEA/kg, (6) control + 0.4 mg ZEA/kg + 1 g MC/kg, (7) control + 0.8 mg ZEA/kg, and (8) control + 0.8 mg ZEA/kg + 2 g MC/kg. The ZEA challenges were shown to linearly depress (P=0.03) average daily gain (ADG) and feed efficiency, but the addition of MC improved (P=0.03) feed efficiency in the overall phase. Coefficient of apparent total tract digestibility of dry matter and nitrogen decreased (linear effect, P<0.05) as the ZEA levels increased and nitrogen digestibility were improved (P<0.01) by MC supplementation. Zearalenone linearly increased (P<0.05) vulva size (width, length, and area). Addition of MC reduced (P<0.05) average vulva width and area. Faecal Lactobacillus counts were increased (P=0.01) and Escherichia coli were reduced (P=0.01) in the MC supplemented treatments at 2 and 4 wk regardless of the level of the MC. Serum malondialdehyde (MDA) concentration increased (linear effect at 2 and 4 wk, P<0.05) and total superoxide dismutase (SOD) and aspartate amino transferase (AST) activities decreased (linear effect at 4 wk, P<0.05) as dietary ZEA dosage increased; MC supplementation reversed (P<0.05) these effects. In experiment 2, 64 pigs (27.13 ± 1.39 kg) that were pre-fed ZEA treatments (0, 0.2, 0.4, or 0.8 mg ZEA/kg) for 28 d in experiment 1, were randomly divided into two halves and fed either control diet or control + 2 g MC/kg for 18 d (2 gilts/pen, 4 pens/treatment). Adding 2 g MC/kg increased (P<0.05) ADG, and decrease the vulva size and serum MAD concentration in pigs pre-fed ZEA diets throughout the 18 d period. Serum SOD concentration increased (P<0.05) in those pigs fed MC on d 9. The results suggest that feeding low levels of ZEA reduced nutrient digestibility, increased oxidative stress, and negatively affected pigs’ growth, and montmorillonite clay was beneficial for detoxification of ZEA in pigs under and after ZEA challenge.