Heat stress exposure changed liver lipid metabolism and abdominal fat deposition in broilers

Figures & data

Table 1. Ingredient composition and nutrient content of diets.

Item^a	Starter (day 1–21)	Grower (day 22–42)
Ingredients, %
Corn	43.42	49.12
Wheat	20.00	20.00
Soybean meal, 44% CP	21.75	18.33
Corn gluten meal, 65% CP	5.00	3.72
Meal and bone meal, 50% CP	2.83	2.40
Tallow	4.44	4.42
Limestone	1.10	1.11
Salt	0.16	0.15
L-Lys·HCl (78.4%)	0.30	0.24
DL-Met, 88%	0.20	0.18
Thr, 98.5%	0.05	0.03
Vitamin premix^b	0.20	0.20
Mineral premix^c	0.10	0.10
Calculated composition
ME, Kcal/kg	3190	3210
Analysed composition, %
CP	21.12	19.79
Lys	1.19	1.02
Met + Lys	0.93	0.82
Ca	0.90	0.85
Total P	0.52	0.49

^a CP, crude protein; HCl, hydrochloric acid; DL-Met, DL-methionine; Thr, threonine; ME, metabolic energy; Lys, lysine; Ca, calcium; Total P, total phosphorus.

^b Provided per kilogram of complete diet: 12,8000 IU vitamin A, 1,600 IU vitamin D₃, 60 IU vitamin E, 1.6 mg vitamin K₃, 0.12 mg biotin, 50 mg choline, 1.2 mg folic acid, 32 mg Nicotinic acid, 16 mg pantothenic acid, 4.8 mg riboflavin, 2.4 mg thiamine (B₁), 3.2 mg vitamin B₆, and 0.03 mg vitamin B₁₂.

^cProvided per kilogram of diet: Mg, 79 mg as manganese oxide; Zn, 60 mg as zinc oxide; Cu,100mg as copper sulphate; Fe, 120 mg as iron sulphate; I, 0.96 mg as potassium iodine; Co, 0.16 mg as cobalt sulphate and Se, 0.24 mg as sodium selenite.

Table 2. Primers for real-time PCR.

Gene^a	ACCession NO.	Primer sequence (5’ to 3’)	Product size (bp)
β-actin	NM_205518.1	F: ATCCGGACCCTCCATTGTC R: AGCCATGCCAATCTCGTCTT	120
ChREBP	NM_001110841	F: CTGACGTGGCTCTTCGAGTG 1 R: TCCAGATGGCATTGTTGAGG	127
SREBP-1c	XM_015294109	F: AGGCGGAGGTGATGGAGAT R: TCGGAGTCACTGCTGCTGTT	112
FAS	NM_205155	F: TTTGGTGGTTCGAGGTGGTA R: CAAAGGTTGTATTTCGGGAGC	215
ACC	J03541	F: GCTTCCCATTTGCCGTCCTA R: GCCATTCTCACCACCTGATTACTG	185
PPARα	AF163809	F: TTT AAC GGA GTT CCA ATC GC R: AAC CCT TAC AAC CTT CAC AAG C	224
MTTP	NM001109784	F: GCAGATGGACAGAGTTGGCT R: ACACCAAAAGTGCAAGGTGC	224
LPL	NM205282	F: CCGATCCCGAAGCTGAGATG R: ACATTCCTGTCACCGTCCAC	186
CPT1	AY675193	F: TAGAGGGCGTGGACCAATAA R: TGGGATGCGGGAGGTATT	229
PPARγ	NM001001460	F: CCAAGGCAGCGGCAAAATAA R: GTGCCCATAAATGATGGCCTAA	188
C/EBPα	NM001031459	F: GACATCTGCGAGAACGAGCA R: GCATGCCGTGGAAATCGAAA	154
C/EBPβ	NM_205253.2	F: GCCGCCCGCCTTTAAA R: CCAAACAGTCCGCCTCGTAA	188

^a β-actin, beta-actin; ChREBP, carbohydrate response element-binding protein; SREBP-1c, sterol regulatory element‐binding transcription factor-1c; FAS, fatty acid synthase; ACC, acetyl-coenzyme A carboxylase; PPAR, peroxisome proliferator–activated receptor; MTP, microsomal triglyceride transfer protein; LPL, lipoprotein lipase; CPT1, carnitine palmitoyl transferase 1; C/EBP, CCAAT/enhancer-binding protein.

Table 3. Effects of heat stress exposure on growth performance of broilers.

Items^a	Control	Heat stress	P-value
Initial body weight, g	740 ± 15.0	742 ± 10.2	0.769
Final body weight, g	2186 ± 46.1	1839 ± 29.5	<0.001
ADG, g	68. 9 ± 1.84	52.2 ± 1.61	<0.001
ADFI, g	146 ± 1.75	118.2 ± 1.94	<0.001
FCR	2.12 ± 0.06	2.26 ± 0.07	0.002

^aADG, average daily gain; ADFI, average daily feed intake; FCR, feed conversation ratio. 

Figure 1. Effects of heat stress exposure on the rectal temperature of broilers. CON, control group; HS, heat stress exposure. The pound key (#) indicated significant difference (P < 0.05).

Figure 2. Effects of heat stress exposure on the relative weight of abdominal adipose and liver of broilers. CON, control group; HS, heat stress exposure. The pound key (#) indicated significant difference (P < 0.05).

Figure 3. Effects of heat stress exposure on the lipid metabolism parameters in serum of broilers. CON, control group; HS, heat stress exposure; TC, total cholesterol; TG, triglyceride; VLDL, very low-density lipoprotein; LDL, low-density lipoprotein; HDL, high-density lipoprotein. The pound key (#) indicated significant difference (P < 0.05).

Figure 4. Effects of heat stress exposure on the lipid metabolism parameters in liver of broilers. CON, control group; HS, heat stress exposure; TC, total cholesterol; TG, triglyceride; VLDL, very low-density lipoprotein; LDL, low-density lipoprotein; HDL, high-density lipoprotein. The pound key (#) indicated significant difference (P < 0.05).

Figure 5. Effects of heat stress exposure on gene expression related to lipid metabolism in the liver and abdominal adipose of broilers. CON, control group; HS, heat stress exposure; ChREBP, carbohydrate response element-binding protein; SREBP-1c, sterol regulatory element–binding transcription factor-1c; FAS, fatty acid synthase; ACC, acetyl-coenzyme A carboxylase; PPAR, peroxisome proliferator–activated receptor; MTTP, microsomal triglyceride transfer protein; LPL, lipoprotein lipase; CPT1, carnitine palmitoyl transferase 1; C/EBP, CCAAT/enhancer-bindingprotein. The pound key (#) indicated significant difference (P < 0.05).

Data availability statement

The original data of the paper are available upon request from the corresponding author.