The effect of feed restriction duration on growth performance, physico-chemical characteristics and fatty acid composition of meat from broilers.

Abstract

The main objective of the study was to determine the effect of feed restriction duration on growth performance, physico-chemical characteristics (colour, ultimate pH, tenderness and cooking loss) and fatty acid composition of meat from broilers. A total of 144 day-old broiler chicks were reared in a deep litter system until slaughter at 42 days. All the chicks were managed in one brooding house for the first 21days. On day 22, the chicks were randomly allocated to three treatments; the control (T1), one week of feed restriction (T2), and two weeks of feed restriction (T3). Three broiler houses with uniform conditions were sub-divided into three compartments. The birds were randomly allocated to each of the nine compartments. Each treatment was replicated three times with 16 birds per compartment being fed as a group and each bird was regarded as the experimental units. The average daily gain (ADG), average daily feed intake (ADFI) and the feed conversion ratio (FCR) were computed for each chick each week. Chickens were all slaughtered at 42 days of age and the slaughter weight, carcass weight, and internal organs weights were recorded. Physico-chemical qualities of chicken breast meat such as colour (L*-lightness, b*-yellowness, a* redness, saturation index and hue angle) and meat ultimate pH (pHu) measurements were taken over a 10 days shelf-life period. Breast muscle was also sampled for cooking loss, tenderness and fatty acid profiles. There were treatment effects on the growth performance of broiler chickens. There was no significant effect (P > 0.05) on the relative weights of the chicken heart, liver, gizzard, feet and heads among the treatment groups except for intestine weight. Treatment 1 had higher live weight than treatment 2 and 3. There was significant effect (P < 0.05) on the cooking loss breast muscle, with treatment 1 having highest values. However, feed restriction had no effect (P > 0.05) on the WBSF of breast muscle, although it was highest in T 3. Feed restriction had no effect (P > 0.05) on hue angle, significant difference (P < 0.05) was observed on meat pHu, L *, a*, b* and saturation index after 24 hours of storage. Birds that were exposed to two weeks of feed restriction had the highest ultimate pH (5.99) followed by one week restriction (6.01) and the broilers which were fed ad libitum (5.89). The pHu values in all the treatments were constant from day 1 to day 6 and then T 2 peaked up at day (6.16) before declining at day 8 (5.91). The L* values in all treatments were constant from day 1 to day 7 and then at day 8, treatment 2 reached its peak L* (58.49) and then declined on day 9 (44.38) with T 3 having similar values. The b* values started to decrease from day 3 to day 6 then peaked up again at day 7 except for T 1. There was no significant treatment effects (P > 0.05) on the SI and Hue angle on breast muscle. There was no treatment effect on the major fatty acids of breast muscle. It was concluded that a one week feed restriction had similar effects on growth performance and meat quality of broiler chickens as non-restriction broilers. The meat quality of the broiler muscle was within the normal range, feed restriction did not affect meat quality of broiler meat. Feed restriction had a minimal effect on physicochemical shelf-life indicators of broiler chickens during storage over 10 days. The observation from this study showed that all the treatment had a minimal effect on the fatty acids of the broiler chicken.