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2018, Vol. 16, No. 2

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/5375

Sirvi

Sirvi 2018, Vol. 16, No. 2 Autor "Baptista, F.J.F." järgi

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  • Pisipilt
    Kirje
    Effect of thermal environment on body temperature of early-stage laying hens
    (2018) Andrade, R.R.; Tinôco, I.F.F.; Souza, C.F.; Oliveira, K.P.; Barbari, M.; Cruz, V.M.F.; Baptista, F.J.F.; Vilela, M.O.; Conti, L.; Rossi, G.
    The thermal comfort condition of early - stage laying hens can be verified by means of physiological variations. The mean surface temperature and cloacal temperature are important parameters to d emonstrate the effect of the thermal environment on the birds. The objective of the present study was to correlate homeostasis and stress with physiological responses (mean surface temperature and cloacal temperature) of lightweight laying hens of the Lohm ann LSL Lite line aged from one to forty - two days when submitted to different thermal environments. A total of 864 birds with the same age, origin and uniform body weight were randomly distributed in four climatic chambers. The characterization of the dif ferent environments was as follows: thermal comfort temperature (33.0 – 19.0 °C ), two cold stress levels (28.0 – 17.0 °C and 25.0 – 17.0 °C ) and one level of heat stress (38.0 °C – 22.0 °C ). The experiment was performed in a completely randomized design in the s ubdivided plots scheme, with four treatments in the plots and the evaluations (days) in the subplots. The means were compared using the Tukey test, adopting the 5% probability level. The birds maintained the physiological responses, based on cloacal and su rface temperatures, within the normal range for all evaluated treatments during the period between 01 and 42 days of life. The surface temperature of the birds varied as a function of the air temperature of each breeding environment, with lower surface temperatures for mild cold and moderate cold treatments.
  • Pisipilt
    Kirje
    Productive performance of broilers at the final stage of breeding submitted to different levels of metabolizable energy in different thermal environments
    (2018) Oliveira, K.P.; Ferreira, C.F.S.; Tinoco, I.F.F.; Andrade, R.R.; Barbari, M.; Cruz, V.M.F.; Baptista, F.J.F.; Vieira, M.F.A.; Conti, L.; Rossi, G.
    The Brazilian poultry industry is an activity in constant development due to the high indices of productive efficiency. The accelerated evolution of poultry production has allowed to obtain early and very efficient broilers able to convert different foods into animal protein. However, due to this intensive breeding system, a series of metabolic and management problems appeared, with emphasis on thermal stress. The objective of this work was to evaluate the physiological responses of broiler chickens in the final stage of breeding (21 to 42 days of life), submitted to two thermal conditions, one representative of the thermoneutrality situation (T1) and one giving a situation of cyclic stress by heat (T2). For each experimental thermal condition, the birds were submitted to different levels of metabolizable energy of 3,050, 3,125, 3,200, 3,275 kcal kg - 1 . At 28, 35 and 42 days, the birds and the feed leftovers were weighed to measure the performance variables: CR (feed intake), GP (weight gain) and CA (feed conversion), viability of the rearing (Vb), productive efficiency index (PEI). As conclusions, the GP was 13.6% higher for the birds maintained at the thermoneutrality situation T1. Th e PEI was 32.5% higher for the birds maintained in T1 condition, when compared to those kept in T2. However, both in thermoneutral and in heat stress conditions, the increase in the level of metabolizable energy in the diet did not influence the performanc e and the productive efficiency index of broiler chickens aged between 21 and 42 days of age.