The Influence of Temperature on the Protein Requirement of Cage Reared Replacement Pullets

Abstract

Two experiments were conducted to determine the influence of environmental temperature from 6 to 20 weeks of age on the protein requirement of cage reared Hyline egg type replacement pullets. The influence of temperature during the laying cycle on performance was also determined. Pullets reared at 29.4° C. weighed less at 20 weeks of age, consumed less feed, were more efficient in the utilization of feed and required more days to reach 50% egg production compared to birds reared at 18.3° C. or under ambient temperature conditions. There was no difference in the performance of replacement pullets due to protein level sequence fed when they were reared at 18.3° C. or under ambient temperature conditions, but birds reared at 29.4° C. were heavier, more efficient in the utilization of feed and required fewer days to reach 50% egg production when they were fed a 20–20.8–18.2–15.6 percent protein level sequence compared to a 20–16–14–12 sequence. The data indicate that the protein requirement of birds reared at 29.4° C. is greater than that for birds reared at 18.3° C. or under ambient temperature conditions. The egg production and egg weight of birds reared at 29.4° C. tended to be reduced compared to that of birds reared under ambient temperature conditions or 18.3° C., but birds reared at 29.4° C. consumed significantly less feed and required less feed/dozen eggs. Rearing temperature did not influence the shell thickness, shell deformation or Haugh units of the eggs. Even though birds reared at 29.4° C. required higher levels of protein to maximize performance to 20 weeks, there was no effect of rearing protein level on subsequent performance during the laying cycle. Birds maintained at 29.4° C. during the laying cycle produced fewer and smaller eggs with thinner shells and higher shell deformation score compared to birds maintained at 18.3° C. or ambient temperature conditions, but birds maintained at 29.4° C. consumed significantly less feed and required less feed/dozen eggs.