The basic track for the John Lennon composition "Good Morning Good Morning" was pulled off the EMI tape storage shelf on March 13 1967 in order to complete a horn overdub consisting of saxes, trombones and a French horn played by members of the 1960s band Sounds Incorporated who were acquaintances of The Beatles. In addition, on March 29 1967, John Lennon overdubbed his lead vocal and harmonizing with himself as well as the addition of backing vocals by the band and the lead guitar solo played by Paul McCartney (very phased on the mono mix, by the way !!).
It was decided to begin and end the song with an array of animal sounds. You can hear a rooster or crow at the beginning and then there is a variety of animal noises at the end which some researchers contest that they follow one another in the order of which animal devours the next animal (not quite). Sounds includes birds (similar to the beginning of "Across the Universe"), cats, dogs, horses, lions, elephants, chickens, etc.
The isolated animal effects tape can be heard unedited on the bootleg CD "The Lost Pepperland Reel" as well as the youtube post below. The tape was assembled by the EMI staff on either March 28 or 29 1967 and mixed into the song at the same time. The stereo mix has a very slight length difference with a few seconds added compared to the mono mix.