Longevity, lifetime pig production and productivity, and age at first conception in a cohort of gilts observed over six years on commercial farms

An observational cohort study was conducted using a producer group of 33 fa rms selected based on their completeness of reproduction data, including da tes of birth, entry to a herd, and removal. Average lifetime pig production and parity at removal in a cohort of 2,265 females born in 1990 were 67.2 pigs born alive and 5.6 parities, respectively. Approximately 90% of farrow ings occurred from the second through the fourth year from birth. Farrowing rates between parities of 2 and 4 were higher than other parities, and pig s born alive from parities 3 to 5 were the greatest among parities. The 10t h and 90th percentiles of age at first conception were 227 and 322 days. In creasing the age at first mating was associated with low farrowing rate (P< 0.01) in parity 0. Older age at first conception was associated with lower parity at removal, shorter reproductive herd life, and fewer lifetime pigs born alive (P< 0.01). Of the 2,265 breeding females, 253 (11.2%) were re-m ated at parity 0 and farrowed. These sows with a record re-mating at parity 0 had lower parity at removal, less lifetime pig production and lower life time productivity than those with no re-mating at parity 0 (P<0.01). It is recommended that unbred gilts 230 days of age or older should be mated soon .