First parity productivity of selected commercial sows

Abstract

This study analysed first parity productivity records over a determined time period of three years from two selected commercial pig production units on the Highveld, and determined whether seasonal differences in productivity occur in relation to seasonal temperature fluctuations, and whether there is a difference in seasonal productivity between farms. The total pool of records used in various models corresponded to first parity breeding records from two farms for 2600 sows born between 1 March 2004 and 28 February 2007. Parameters of performance taken from the records included 1) Date of birth (DoB), 2) Year of Birth (YoB) of gilt, 3) Season of Birth (SB) of gilt, 4) Age at first service (AFS), 5) Season of First Service (SS), 6) Year of First Service (YoS), 7) Number of Services (NoS), 8) Farrowing date (FD), 9) Year of Farrowing (YoF), 10) Season of Farrowing (SF), 11) Total number of piglets born (TB), 12) Number of piglets born alive (BA), 13) Number of stillborn piglets (BD), 14) Number of mummified piglets (GA), 15) Weaning date (WD), 16) Backfat thickness (BF) of the gilts at farrowing (BFF), 17) BF at weaning (BFW) and 18) Weaning to service interval (WSI). The gilts from both farms were of the same synthetic genetic line and originated from one of three Farms of Birth (FoB). Daily maximum and minimum outdoor temperature data for the period between 1 January 2005 and 31 December 2007 were obtained from the South African Weather Service for the areas in which the production farms are situated. There were seasonal differences in productivity between years, within years and between farms but were not necessarily directly linked to the seasonal temperature fluctuations in all cases. The FoB influenced AFS significantly (P<0.0001). For farms pooled there was no seasonal difference in AFS between gilts born in summer and gilts born in autumn, winter and spring. However, gilts born in autumn were younger at AFS than gilts born in winter (P < 0.0001) and spring (P=0.0008), but differences in AFS of gilts born in winter and spring were not significant. There was no difference in TB or BA from sows receiving either one or two services before successful conception. There was no seasonal difference of TB or BA between gilts first served in summer, autumn, winter or spring. There were, however, fewer TB from gilts served during 2006 than from gilts served during either 2005 (P=0.0007) or 2007 (P=0.0002) but differences in TB from gilts served during 2005 and 2007 were NS. There was no difference in BA between years. For farms pooled, there was no seasonal difference in WSI between gilts farrowed in summer, autumn, winter or spring. There was a tendency for the sows to return to service during the summer months more than in any other season. There was a seasonal difference in number of piglets born per litter between farms between years.