title: Effects of dietary DL-2-hydroxy-4(methylthio)butanoic acid supplementation on growth performance, indices of ascites syndrome, and antioxidant capacity of broilers reared at low ambient temperature.
abstract: This study examined the effects of dietary DL-2-hydroxy-4(methylthio)butanoic acid (DL-HMTBA) supplementation on growth performance, antioxidant capacity, and ascites syndrome (AS) in broilers reared at low ambient temperature (LAT) from 7 to 28 days of age. Eight hundred 7-day-old broilers were randomly assigned to two ambient temperatures (LAT and normal ambient temperature [NAT]), four supplemental DL-HMTBA levels (0.17, 0.34, 0.51, and 0.68 %) of the basal diet in a 2 × 4 factorial arrangement (ten replicate pens; ten birds/pen). LAT and NAT indicate temperatures of 12-14 and 24-26 °C in two chambers, respectively, and broilers were reared at these temperatures from 7 to 28 days of age. LAT significantly decreased body weight gain (P < 0.001), serum glutathione (GSH) content (day 14, P = 0.02; day 28, P = 0.045), glutathione peroxidase (GSH-Px) activity, and total antioxidant capacity (T-AOC) at 21 days (P = 0.001, 0.015) and 28 days (P = 0.017, 0.010) and increased feed conversion ratio (FCR) (P < 0.001), serum malondialdehyde (day 21, P = 0.000) and protein carbonyl Level (day 14, P = 0.003; day 21, P = 0.035). As for incidence of AS, there were significant effects of LAT on red blood cell (RBC) count (P < 0.05), hematocrit (HCT) (P < 0.05), and the right to total ventricular weight ratio (RV/TV) at 21 days (P = 0.012) and 28 days (P = 0.046). Supplementation of DL-HMTBA markedly decreased RV/TV at day 28 (P = 0.021), RBC (day 21, P = 0.008), HCT (day 21, P < 0.001), mean cell hemoglobin (day 14, P = 0.035; day 21, P = 0.003), and serum protein carbonyl level (day 21, P = 0.009), while significantly increased serum GSH content (day 14, P = 0.022; day 28, P = 0.001), SOD and GSH-Px activities at 21 days of age (P < 0.001 and P = 0.037). The optimal supplemental DL-HMTBA levels in basal diet of broilers aged from 7 to 28 days under low or normal temperatures were similar, so the authors recommended supplemental of DL-HMTBA level was 0.46 %.
authors.affiliation: Institute of Animal Nutrition, Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
authors.forename: G L
authors.initials: GL
authors.lastname: Yang
authors.affiliation: Institute of Animal Nutrition, Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
authors.forename: K Y
authors.initials: KY
authors.lastname: Zhang
authors.affiliation: Institute of Animal Nutrition, Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
authors.forename: X M
authors.initials: XM
authors.lastname: Ding
authors.affiliation: Institute of Animal Nutrition, Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
authors.forename: P
authors.initials: P
authors.lastname: Zheng
authors.affiliation: Institute of Animal Nutrition, Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
authors.forename: Y H
authors.initials: YH
authors.lastname: Luo
authors.affiliation: Institute of Animal Nutrition, Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
authors.forename: S P
authors.initials: SP
authors.lastname: Bai
authors.affiliation: Institute of Animal Nutrition, Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
authors.forename: J P
authors.initials: JP
authors.lastname: Wang
authors.affiliation: Institute of Animal Nutrition, Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Xuan
authors.affiliation: Institute of Animal Nutrition, Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
authors.forename: Z W
authors.initials: ZW
authors.lastname: Su
authors.affiliation: Institute of Animal Nutrition, Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China. zqf@sicau.edu.cn.
authors.forename: Q F
authors.initials: QF
authors.lastname: Zeng
mesh_terms: D000818:Animals; D001201:Ascites; D002645:Chickens / Q000097:blood / Q000254:growth & development; D019587:Dietary Supplements; D005978:Glutathione / Q000097:blood; D005979:Glutathione Peroxidase / Q000097:blood; D006403:Hematologic Tests; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D008715:Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013696:Temperature
chemical_list: D008315:Malondialdehyde; C008391:alpha-hydroxy-gamma-methylmercaptobutyric acid; D008715:Methionine; D005979:Glutathione Peroxidase; D005978:Glutathione
keywords: Antioxidant capacity; Ascites syndrome; Broiler; DL-2-Hydroxy-4(methylthio)butanoic acid; Low ambient temperature