Combined effect of short-term temperature stimulation during the hatching phase and of protein and energy concentrations in the diets on performance of laying-type cockerels of different strains

Abstract

The following described study was carried out to investigate the hypothesis that short-term warm stimulation in incubation temperature during the last days of incubation can improve hatching results and have long-lasting effect on performance, also in laying-type cockerels. The results of the incubation trial showed that a short-term increase in temperature by 1°C over the standard for 2 hours daily (38.2–38.4°C) improved the hatching results by 3.5% and in female and 7.7% in male LB chickens and by 2.0% in female and 5.5% in male LT chickens. The statistical evaluation of the feed level as single effect on performance of cockerels demonstrated a high dependence (P < 0.05) of the protein and energy concentration in the feed on the daily feed intake, the body weight, and the feed to gain ratio. The feed to gain ratio was significantly higher in the low feed groups (2.59 kg/kg) compared to the high feed groups (2.33 kg/kg) over the 70 days growing period. The origin of the cockerels was of great importance on the feed intake (LB-45.7 g/d/bird; LT-47.0 g/d/bird) over the growing phase D22–50 and on body weight at D21 (LT-256 g; LB-242 g) and D70 (LT-1404 g; LB-1380 g). The feed to gain ratio of the LT-cockerels (LT-2.24 kg/kg) was significantly higher compared to the LB- birds (LB-2.16 kg/kg) at the age of D22 to D49, but in the next growing period (D50–70) the order changed and over the total growing period (D1–70) there was no difference between the two origins of cockerels. Over the total growing period (D1–70), the combined effect of incubation temperature+origin of cockerels demonstrated dependence (P <0.05) of both parameters on the daily feed intake and daily weight gain, as well as on the final body weight. A significant interaction (P <0.05) between the origin of cockerels+feed level on daily feed intake (D1-D70) underlined the importance of both these factors on growing parameters. At slaughtering at D49 the percentage of carcass and mass of two legs were statistically different between LT (62.8%; 164.8 g) and LB (61.0%; 155.8 g) cockerels. At the end of the trial (D70) the mass and percentages of meat and organs were not different between LB and LT birds. A firm statistical difference in the percentage of liver and gizzard was calculated between low and high feed level at the age of D49 (gizzard – 2.8%, 3.1%) and D70 (gizzard – 2.6%, 2.8%). The combined effect of incubation temperature+origin of cockerels demonstrates dependence (P < 0.05) of both parameters on yield and percentage of breast meat over the total growing period (D1–70).