The aim of this study was to investigate effects of L-threonine (L-Thr) supplementation on the growth performance, immunity, antioxidant status, and intestinal health of broilers at the early age. One hundred and forty-four 1-day-old male broiler chicks (Arbor Acres Plus) were allocated into 3 treatments with 6 replicates of 8 birds each, and fed a basal diet (analyzed Thr content, 7.87 g/kg) supplemented with 0 (control diet), 1 and 3 g/kg L-Thr for 21 d, respectively. Treatments did not alter growth performance of broilers. Compared with control, 1 g/kg Thr supplementation increased relative weight of spleen (P = 0.013). A higher level of Thr (3 g/kg) increased relative weight of thymus (P = 0.003). The supplementation of 3 g/kg Thr reduced Escherichia coli (P = 0.040) and Salmonella colonies (P = 0.015), whereas increased Lactobacillus colonies (P < 0.001) in the cecal contents. Thr supplementation increased intestinal villus height (P < 0.05), and the ratio of villus height to crypt depth (P < 0.001), and the values for these parameters were intermediate with 1 g/kg Thr. Goblet cell density was increased by Thr supplementation (P < 0.001). The jejunal immunoglobulin G content was increased by the inclusion of Thr (P = 0.002). Broilers fed diet supplemented with 1 g/kg Thr exhibited increased concentrations of jejunal immunoglobulin M (P = 0.037) and secretory immunoglobulin A (P = 0.018). Likewise, 3 g/kg Thr inclusion increased ileal secretory immunoglobulin A content (P = 0.023). The jejunal malondialdehyde accumulation was reduced by Thr inclusion (P = 0.012). A higher level of Thr inclusion also reduced malondialdehyde content in the serum (P = 0.029). The high level of Thr inclusion (3 g/kg) upregulated mucin-2 mRNA expression (P = 0.034), whereas downregulated the mRNA abundances of interferon-γ (P = 0.036) and interleukin-1β (P = 0.031) in the ileum. In conclusion, L-Thr supplementation can improve immunity, antioxidant capacity, and intestinal health of broilers at an early age.

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The current study was conducted to investigate the effect of zinc (Zn) bearing palygorskite (ZnPal) inclusion on the growth performance, mineral content, meat quality, and antioxidant status of broilers. A total of 240 one-day-old Arbor Acres broiler chicks were randomly allocated into 5 dietary treatments with 6 replicates of 8 chicks. Broilers in the 5 treatments were fed a basal diet supplemented with 0, 20, 40, 60, and 80 mg/kg Zn diet in the form of ZnPal for 42 d, respectively. Birds exhibited similar average daily gain (ADG), average daily feed intake (ADFI), and feed/gain ratio (F:G) among groups during the 42-day study (P>0.05). ZnPal supplementation linearly increased iron (Fe) (P=0.031) and magnesium (Mg) (P=0.002) content in the pectoralis major muscle. Similarly, the inclusion of ZnPal tended to increase Zn content in the thigh (P=0.072) and linearly increase Zn content in the pectoralis major muscle (P=0.055). The concentration of copper (Cu) in the thigh was linearly decreased by ZnPal inclusion (P=0.011). Meanwhile, a quadratic trend for reduced Cu content was observed in the pectoralis major muscle (P=0.074) and thigh (P=0.082), respectively. The supplementation of ZnPal linearly reduced cooking loss in the pectoralis major muscle (P=0.013), and linearly (P=0.029) and quadratically (P=0.034) decreased cooking loss in the thigh. Malondialdehyde (MDA) concentration in the thigh was linearly (P=0.020) and quadratically (P=0.017) reduced by ZnPal inclusion. Additionally, ZnPal supplementation tended to linearly enhance total antioxidant capacity (T-AOC) activity of the pectoralis major muscle (P=0.083). The results obtained in the current study indicated that ZnPal inclusion could alter muscular mineral accumulation, improve meat quality, and enhance the muscular antioxidant capacity of broilers, and Zn supplementation in the form of ZnPal at the dosage of 20 mg/kg would be sufficient in improving meat quality and muscular oxidative status.

The present study was conducted to investigate different levels of palygorskite supplementation on the growth performance, meat quality, muscular oxidative status, and mineral element accumulation of broilers. One hundred ninety-two 1-day-old Arbor Acres broiler chicks were allocated to four dietary treatments with six replicates of eight chicks per replicate. Birds in the four treatments were given a basal diet supplemented with 0, 5, 10 and 20 g/kg palygorskite for 42 days, respectively. Compared with the control group, neither 5 g/kg nor 10 g/kg palygorskite inclusion affected growth performance of broilers during the 42-day study (P > 0.05). However, the highest level of palygorskite supplementation at 20 g/kg increased feed/gain ratio (F/G) of broilers (P < 0.001). Yellowness (P < 0.001) and redness (P = 0.003) of breast muscle and yellowness of leg muscle (P = 0.001) were decreased by palygorskite supplementation at the levels of 10 g/kg and especially 20 g/kg. In addition, redness of leg muscle was also reduced by the inclusion of 20 g/kg palygorskite (P = 0.009). In contrast, malonaldehyde (MDA) accumulation in the breast muscle was significantly increased by 20 g/kg palygorskite supplementation (P < 0.001). Supplementation of palygorskite at either 10 or 20 g/kg significantly decreased lead (Pb) accumulation in the breast (P = 0.001) or thigh (P = 0.045) and copper (Cu) accumulation in the breast (P = 0.022). In conclusion, growth performance, meat color, and antioxidant capacity of meat would reduce with the increasing level of palygorskite supplementation, whereas a higher level of palygorskite (10 or 20 g/kg) can alter mineral element accumulations in muscles as evidenced by reduced muscular Cu and Pb contents.