Richard Barnes denied doing anything deliberately to harm baby Grace and said their heads collided as he went to put her over his shoulder to prevent her from choking on her own vomit.
Barnes, who had drunk four miniature bottles of spirits and a bottle of lager on the day Grace was injured, told Leeds Crown Court he also fell on top of the baby as he carried her.
The 27-year-old was left on his own to look after his daughter for around 20 minutes while his partner, Stephanie Rudd, drove her mother home in November 2011.
He said he was feeding Grace her bottle when she was sick.
He went to move her to put her over his shoulder because he was worried she might choke on her vomit but as he lifted her towards his shoulder the pair clashed heads so hard it made his “ears ring”, he told the court.
He stood up, still holding the baby, and the next thing he remembered was being on the floor with Grace underneath him, he said.
Barnes, of Crowther Street, Castleford, West Yorkshire, said he did not know how or why he had fallen.
The Haribo machine operator said he then put Grace into her crib without looking at her and went to a shop 100 metres away to buy two miniature bottles of vodka.
He said he drank the vodka immediately after returning home and then noticed the baby looked “really white, really pale” when he picked her up.
Barnes said: “I didn’t know what to do. I can remember running around looking for my phone. I couldn’t remember where I put it, I was running around in a panic.”
Miss Rudd returned home and he told her he and Grace had clashed heads. An ambulance was called and the baby was taken to hospital with head injuries. She died four days later.
Barnes did not tell his partner, paramedics or doctors at the hospital about the fall but, before he was arrested on suspicion of murder, he told his father: “I’ve fallen on her dad.”
He told the court today that he felt “totally ashamed” for not telling anyone about the fall and he said he hated himself for going to the shop to buy alcohol after Grace had been injured.
Paul Greaney QC, defending, asked Barnes why he tried to harm himself after his daughter’s death.
The defendant answered: “I didn’t feel my life was worth living without Grace.”
When asked if he had done anything to deliberately harm his daughter at any stage on November 19, he said: “No.”
Barnes told the court he cried when Miss Rudd told him she was pregnant and was “over-the-moon”.
He said it was a pleasure to look after Grace, who he described as “good as gold”, and said he was the happiest he had ever felt before the baby’s death.
In cross-examination, Richard Mansell QC, prosecuting, said Barnes had made up the story about the clash of heads and had lied to the police.
Mr Mansell said: “You knew you were responsible for physically assaulting your daughter and it was dawning on you how serious it was.”
He added: “The truth was you had assaulted her violently, either by stamping on her or doing something similarly forceful.”
Barnes replied: “No, I didn’t.”
The trial continues.