Effect of Sex, Level and Period of Feed Restriction During the Starter Stage on Productivity and Carcass Characteristics of Ross 308 Broiler Chickens in South Africa

Evaluation of apple (Malus domestica) cider vinegar and garlic (Allium sativum) extract as phytogenic substitutes for growth-promoting dietary antibiotics in sexed broiler chickens

Tightening global regulations on the use of subclinical dietary antibiotics to enhance broiler growth are in response to increasing concern about the risk of resistance and their residues in animal products. The study evaluated the potential of apple cider vinegar (ACV) and garlic extract (GAE) as safer, phytogenic alternatives. A batch of 390 mixed-sex Ross 308-d-old broiler chicks was received into an open, deep litter house, and feather sexed in the second week into 30 experimental units of 13 birds per 2.03 m2 pen. From days 1 to 22, all chicks were on a 200 g/kg crude protein, coccidiostat-treated commercial starter diet. During the grower (16 to 28 days) and finisher (29 to 42 days) phases, chick pens were assigned treatments in a 2 (sex) × 5 (additives) factorial experiment replicated three times. The GAE was a pure extract, while ACV was produced by fermenting 1,000 g fresh apple and 80 g supplementary brown cane sugar in 1.3 liters of water for 4 wk. The five treatments comprised antibiotic (15% granular zinc bacitracin and 12% valinomycin sodium, each at 500 g/tonne) grower (190 g/kg crude protein, 13.0 MJ ME/kg) and finisher (165 g/kg crude protein, 13.2 MJ ME/kg) commercial diets with untreated drinking water as positive controls (PC), antibiotic-free duplicates of the PC diets with untreated drinking water as the negative controls (NC), with 3 mL/L filtered ACV in drinking water (T1), 2 mL/L filtered GAE-treated drinking water (T2), or mixed (3 mL/L ACV + 2mL/L GAE) additive drinking water (T3). Males had higher (P < 0.05) feed intake than females in both growth phases. Birds on the PC gained more (P < 0.05) weight than others. Birds on the PC consumed more feed (P < 0.05) during the finisher phase than T1, T2, and the NC. Birds on the PC had a lower (P < 0.05) grower-phase feed convesion (feed:gain) ratio (FCR) than others, and lower (P < 0.05) FCR during the finisher phase than birds on T1 and T3. Birds on the PC had higher (P < 0.05) percent spleen weight than birds on T1, with smaller proventriculi (P < 0.05) than on NC, T1, T2, and T3, and smaller gizzard weight than birds on the T2 and T3. Birds on the NC exhibited less dressing percentage (P < 0.05) than all other treatments. Meat pH was higher (P < 0.05) in males. In conclusion, in contrast to dietary antibiotics, except for improved dressing percentage, the ACV and GAE did not express phytogenic benefit at the experimental dosage.

Improvement in broiler performance by feeding a nutrient-dense diet after a mild feed restriction

Background: The use of early nutrient-restriction programs in broilers can prevent complications such as increased body fat deposition and its consequences. However, feed restriction not always gives the expected results. Objective: To assess the effect of two levels of feed restriction followed by a re-alimentation period with five increasing nutrient levels on growth performance and immune response of broiler chickens. Methods: A total of 330 animals were used. The treatments were: 25 (T25) and 35% (T35) quantitative feed restriction during the starting period, and 0, 2.5, 5, 7.5, 10, and 15% increased energy and protein contents during the growing and finishing periods. Results: For all the T25 treatments, except for T25-0, feed intake (FI) and body weight gain (BWG) were higher, and feed conversion rate (FCR) was lower (p<0.05) compared to the control treatment. In that group, the response of FI and BWG to the increased nutrient density was mostly quadratic (p<0.001), whereas that of FCR was linear (p<0.001). The FI and BWG results were less homogeneous in the T35 treatments, but FCR was lower compared to the control treatment (p<0.05) in all of them. The FCR showed no differences (p>0.05) between treatments during the finishing period. Conclusion: Feeding a nutrient-dense diet after a period of mild feed restriction gives the best results, while increasing nutrient density after a more severe feed restriction does not improve productive results compared to a standard diet. Carcass traits and immune function were not affected by restriction level or nutrient density.

Impact of restricting feed and probiotic supplementation on growth performance, mortality and carcass traits of meat-type quails

The objective of this study was to evaluate the effects of quantitative feed restriction, along with dietary supplementation with a probiotic blend (Protexin) as a natural growth promoter, on the performance, water consumption, mortality rate and carcass traits of meat-type quails. A total of 250 1-day unsexed quails were randomly allocated to five equal groups in a completely randomized design. The first group (A) fed a basal diet without any restriction (24 hr/day); the second group (B1) fed the basal diet for 20 hr/day; the third group (B2) fed the basal diet enriched with probiotic (0.1 g/kg diet) for 20 hr/day; the fourth group (C1) fed the basal diet for 16 hr/day; and the fifth group (C2) fed the basal diet enriched with probiotic (0.1 g/kg diet) for 16 hr/day. Birds were fed ad-libitum from 0-14 days of age, and then the feed restriction regimes started from 14 till 28 days of age. Results showed that quails in the control-group consumed more feed and water than the other treatment groups (p < .01), however their body weights did not differ (p > .05) compared with the other treated groups. The best feed conversion values were achieved in quails supplemented with probiotic blend (B2 and C2) in comparison with the other groups (p < .01). Feeding probiotic had a positive effect on bird health which reduced the mortality rate. Further, mortality rate was significantly reduced (p < .05) by feed restriction, with or without probiotic supplementation. No carcass parameters were significantly affected (p > .05) by treatments. Our results show that quail could be reared under a feed restriction system, for 4-8 hr daily, along with dietary supplementation of probiotic as growth promoter for better growth performance.

Effects of the level and duration of feeding restriction on carcass components of broilers

Abstract. The effects of the restriction of the advised daily feed intake (ADFI) during 1 or 2 weeks on broiler body weight (BW) and carcass composition were studied. A total of 150 1-day-old male broilers (Ross-308) were randomly allotted to a control and four experimental treatments with three replicates per treatment. Broilers were subjected to a feeding restriction equal to 75 and 50 % of ADFI, either for a 7- or a 14-day period, between the 7th and 14th and 7th and 21th day of age, respectively. The BW and carcass composition were determined on day 42. From the findings, neither of the two levels of restriction nor the two time intervals had significant effects (P > 0.05) on the BW or breast and leg weight and proportion, liver and most of the body components. However, the feeding treatments show a tendency (P = 0.078) to influence the BW, with birds fed 75 % of ADFI for 14 day being heavier than the control group. For eviscerated carcass weight, an effect (P = 0.002) was observed, with birds fed 75 % of ADFI for 14 day having heavier carcasses (P < 0.05) than those in control group. The abdominal fat, both with regard to weight and proportion, was slightly influenced by dietary treatments (P > 0.05). From our results, it can be concluded that the applied feeding restrictions have a neutral or slightly beneficial effect on broiler growth traits and carcass composition.