Efeito do substrato, revolvimento e cal sobre características físicas e microbiológicas da cama na produção de frangos de corte.

Abstract

To evaluate the effects of substrates, stirring (rotation of the litter with a pitchfork) and quicklime on productive variables and physic-chemical properties of the bed a total of 216 male Cobb broilers were randomly allotted to 18 pens with new litter (experimental unit). A split-plot design with six treatments allocated to main plots were used: T1 - wood shavings (WS) + WDR; T2 - WS without revolving up to 14 days (WODR); T3 - rice hulls (RH) + WDR; T4 - RH + WODR; T5 - mixture of 50% RH and WS + WDR; T6 - mixture of 50% RH and WS + WODR. Two treatments were allocated to subplots: 0 and 300g CaO m-2 litter. Weight gain, body weight, mortality and footpad dermatitis were evaluated. Weekly physic-chemical analysis was performed in the poultry litter. Data were analyzed by two-way ANOVA. The treatment means were compared by LSMeans. To achieve homogeneity of variance, the colony-forming units were logarithmically log10(var+1) transformed. The correlations between poultry litter parameters were evaluated by Pearson correlation procedures. The comparisons of least square means for the stirring and not stirring treatment and for the use of rice hulls or wood shaving substrates were conducted by orthogonal contrasts. A probability of P≤ 0.05 was required for statements of significance. Parallel to this trial a survey data collection was performed in a poultry industry integrator located in Southern Brazil to evaluate performance of producer regarding to different management practices of the poultry litter. This data were analyzed using stepwise regression. The stirring for the first 14 days of a bird’s life affected pH and ammonia in poultry litter. Neither the type of substrate nor the act of stirring affected the CFU. The incorporation of 300 g CaO m-2 litter efficiently reduced the CFU observed on BHI, CN and MC media by 57.2, 66.9% and 92.1%, respectively, compared to control (6.4%, 17.9 and 46.1) (P<0.001). In the data collection was observed a relationship between slaughter age with daily weight gain and production factor of the producer. According to this study, between 42 and 49 days of birds age, delaying one day to slaughter, reduces 0.07 the Production Efficacy Factor (P=0.025) bringing economical losses for the producer. It was observed that stirring at final week of rearing (35-42 days of age) reduces condemnation and carcass lesions at slaughter house.