Effect of Phosphorylated Tocopherol Mixture on Growth Performance and Meat Quality in Broiler Chickens

This study investigated the effect of a novel phosphorylated tocopherol mixture (TPM) on the growth performance and meat quality in broiler chickens reared in normal temperatures (NT) or cyclical high temperatures (CHT). Three hundred and sixty Ross 308-day old broilers were housed in groups of 5 in cages (n = 12/treatment). From day of placement until d 35, broilers were assigned to 1 of 3 vitamin E-adequate, wheat and soybean meal-based diets containing TPM at 0 (Control; 20ppm of Vit E), 10 or 20 mg/kg diet. Experimental diets were formulated by commercial nutritionists (ACE Livestock Consulting, Australia) to reflect industry norms. From 21-35 d of age, birds were exposed to either normal temperatures (NT; 22±1°C; 60% RH) or cyclical high temperature (CHT; 32±1°C; 8 h; 80-90% RH and 16 h at 22±1°C; 60% RH).

There was no interaction between CHT and TPM on growth performance. The body weight (BW) of birds assigned to the CHT treatment was lower on d 35 when compared with the birds assigned to the NT treatment. There was an effect of TPM inclusion on final (d 35) BW. Birds offered the CD + TPM 10 had an increased BW (2511 g/b) when compared with the CD group (2454 g/b; P = 0.016). There was significant effect of CHT on average daily feed intake (ADFI), average daily gain (ADG) and feed conversion ratio (FCR). Birds assigned to the CHT treatment had decreased ADFI (163 vs 167 g; 21-35 d; P = 0.015), decreased ADG (105 vs 110 g; 21-35 d; P < 0.001 and overall; 68.6 vs 70.1 g; P = 0.021) and increased FCR (1.55 vs 1.51; 21-35 d; P = 0.002 and overall; 1.47 vs 1.45; P = 0.001) when compared with the CD group. There was an effect of TPM inclusion on growth performance. Birds offered the CD + TPM 10 diet had increased ADG (110 vs 107 g; 21-35 d; P = 0.027 and overall; 71 vs 69 g; P = 0.010) when compared with the CD group, and decreased FCR (1.33 vs 1.36; 0-21 d; P = 0.024) when compared with the TPM 20 diet. The growth performance of birds offered the CD + TPM 20 was not different when compared with the CD group. Meat quality was determined on 1 bird per cage (d 35). Birds assigned to the CHT treatment had increased core breast muscle temperature at 24 h (11.1 vs 10.0 °C; P < 0.001), decreased pH at 24 h (5.98 vs 6.07; P = 0.003) and decreased drip loss after 5 days (4.0 vs 5.3%; P < 0.001) when compared with birds assigned to the NT treatment. The shear force value of cooked breast meat from the birds assigned to the CHT treatment was higher (tougher; 3545 vs 2827 g; P < 0.001) than birds assigned to the NT treatment. There was no effect of CHT or diet on breast colour at d 0 or d 7. There was a non-significant decrease (P = 0.057) in drip loss of birds assigned to the CD + TPM 10 diet when compared with the CD group.

In conclusion, CHT suppressed growth performance and reduced tenderness value of breast meat in broiler chickens. Broilers offered a diet containing TPM at 10 ppm improved growth performance over the whole growing periods in both NT and CHT regimes and tended to reduce drip loss following storage of breast muscle.