Optimizing Gilt Body Weight At First Insemination, By Graeme McDermid South West Ontario Veterinary Services

Gilts often account for 18 to 20 % or more of the breeding herd. Gilt reproductive performance therefore has a significant effect on overall sow herd productivity. Gilt management factors can affect reproductive performance and longevity in subsequent parities. Gilt age, body weight, backfat thickness, and loin muscle depth are some of the more common factors that are believed to have an effect on reproductive success. A number of researchers have looked at the effect of age and body weight at first insemination in various genetic programs. These Spanish researchers wanted to assess the effect of body weight (BW) at first service on sow performance during first parity and overall lifetime reproductive efficiency. In this particular study, a total of 360 DanBred gilts were categorized into three groups according to their BW at first insemination: (1) Small sows (< 135 kg BW; n = 108); (2) Medium sows (135-150 kg BW; n = 155); (3) Large sows (> 150 kg BW; n = 63). Gilts were studied from first insemination to first weaning and then reproductive parameters were monitored until culling. Sow body status, litter size and weight, farrowing rate, weaning-to-conception interval, and lifetime performance were recorded.

The researchers found the following:

  • Small sows had the lowest body weight, backfat thickness, and loin depth during gestation.
  • Small sows had the smallest number of total piglets born and longest weaning-to-conception interval at first parity.
  • Small sows had an average of one less piglet born during their productive life.
  • Small sows tended to have a higher culling rate over three parities. 18% of small sows were removed from the herd before reaching three parities. (Medium was 14% and Large was 5% )
  • There was no significant effect of gilt age for most of the variables that were tested.
  • Small and medium group sows in this study did not reach the optimal BW recommended by Kim et al. in a previous study. (Kim et al who showed that ensuring gilts achieve  210 kg BW at day 109 of gestation leads to the lowest culling rate and highest number of piglets born alive over six parities.)

Take Home Messages:

  • Age at first insemination was much less important than body weight at first insemination. This finding is consistent with more recent research.
  • Small sows < 135 kg body weight at first insemination had the poorest overall reproductive performance and sow herd longevity while the large sow group had the best performance.
  • The researchers warned that it may be possible that if gilts get really overweight that  there could be reproductive problems. (Excessive fat reserves (18–23 mm) or excessive body weight (>170 kg) at first farrowing may be tied with an increased risk of being culled. Body condition and body weight at first farrowing is directly correlated with those parameters at first insemination. )
  • Achieving optimal body weight at first service is essential for maximizing the sow’s lifetime performance.

Submitted by Graeme McDermid – Production Services

Source: María José Carrión-López , Juan Orengo , Josefa Madrid , Antonio Vargas , Silvia Martínez-Miró  Effect of Sow Body Weight at First Service on Body Status and Performance during First Parity and Lifetime  Animals (Basel) . 2022 Dec 2;12(23):3399. doi: 10.3390/ani12233399.