121 Precision Feeding Gilts for Lifetime Performance

Abstract Gilt feeding during the rearing period may greatly impact longevity, yet gilts are often fed ad libitum with only one diet from 30 kg until first service. The objective of this abstract is to review the Danish approach to gilt feeding during rearing to maximize sow longevity and lifetime productivity. A study followed 1,341 DanBred Hybrid gilts during rearing to evaluate effects of weight and backfat at first farrowing on sow longevity. Age, weight and P2 backfat (BF) at first service were 201-279 d, 105-210 kg, and 6-22 mm, respectively. As weight at first service increased, the number of productive days (PD) in the sow’s life decreased linearly (P = 0.003), and a decrease of 16 kg at first service increased PD by 55 days. A non-linear relationship between BF and PD was identified (P = 0.003), and longevity was quite stable in the interval 13-18 mm BF, but a reduction from 14 to 11 mm BF resulted in a 47-day reduction in PD. When adjusting for weight effect, age had no direct effect on number of PD (P = 0.833). Furthermore, the effects of age at first service and sow longevity were analyzed using data from the SEGES InSight database comprising a total of 360,319 gilts from 319 different herds (2021-2024). Compared with gilts serviced at 211-230 d, those with an age at first service of 231-250 d OR = 1.09, 251-270 d OR = 1.19 or 271-400 d OR = 1.41 had significantly higher odds (P 0.001) of farrowing fewer than three times. Similarly, analyzing data from 526,608 gilts from the same herds serviced from 2021-2025 showed that longevity of sows that were serviced first time as gilts at an age of 211-230 days or earlier was significantly improved (P 0.001) compared with gilts serviced at an older age, as hazard-ratios were 1.05, 1.09 and 1.21 for gilts serviced at 231-250 d, 251-270d, and 271-400 d, respectively. Based on these results, a three-phase feeding strategy (30-60 kg, 82 g SID Lys/kg; 60-110 kg, 6.3 g SID Lys/kg and from 110 kg to first service, 4.2 g SID Lys/kg) is recommended under Danish conditions to control gilt growth rate and backfat retention. This is combined with a feeding curve reaching a plateau of 3.3 kg/d at an age of 23 wk. This provides an opportunity to breed gilts in their second heat at an age of 30-33 wk, weighing 150-165 kg and with 13-15 mm backfat. In conclusion, more attention is needed during gilt rearing. Gilts should be bred at a narrow weight range as this will increase sow longevity and thus maximize lifetime performance.