Treffer: Reproductive performance, removal patterns, and retention of gilts with different first-litter size in hyperprolific Danish Landrace × Yorkshire sows under tropical conditions.

This study evaluated the litter size potential of Danish Landrace × Yorkshire sows under tropical conditions, analyzed removal patterns, and assessed the impact of first-parity litter size on the incidence of second-parity syndrome and gilts retention in hyperprolific sows. This retrospective analysis used data from a commercial swine herd in western Thailand, comprising 41288 litters from 11301 Danish Landrace × Yorkshire sows farrowing between January 2020 and December 2022. Removal data were collected from 7211 gilts and sows. Stayability was assessed based on the average parity at removal and the proportion of animals removed at parity ≥4. Sows were categorized into three groups based on the total number of piglets born per litter (TB) in their first parity: small (7-13), moderate (14-19), and large (≥20). Litter size and the incidence of second-parity syndrome were compared across these groups. On average, each litter had 16.5 ± 4.5 TB, with 14.6 ± 4.2 born alive. The rates of stillbirths and mummified fetuses per litter were 7.7 % and 3.2 %, respectively. TB increased from parity 1 to parity 3 (P < 0.001), followed by a decline from parity 4 onward. The average removal parity was 4.5 ± 3.0, with 59.9 % of animals removed at parity ≥4. Reproductive problems (36.0 %) and old age (35.7 %) were the most common reasons for removal. Among sows, the most frequent reproductive issues included vaginal discharge syndrome (36.3 %), anestrus (30.3 %), and failure to conceive (20.2 %). In gilts, reproductive problems accounted for 73.9 % of removals, primarily due to anestrus (38.1 %), failure to conceive (29.0 %), and vaginal discharge syndrome (28.0 %). Second-parity syndrome was observed in 34.9 % of sows, with an average decline of 3.4 ± 2.3 piglets in affected sows. The prevalence of second-parity syndrome ranged from 8.8 % in sows with small first litters to 58.4 % in those with large first litters (P < 0.001). However, when defined as an absolute number of piglets (≤13 TB), small second-parity litters were most frequent in sows with small first litters (16.5 %) compared with moderate (10.0 %) and large (6.0 %) litters (P < 0.001). Regression analysis showed that each additional piglet in the first litter increased the second-litter size by 0.35 piglets (R ²  = 0.085; P < 0.001). In conclusion, Danish Landrace × Yorkshire sows in tropical conditions showed high litter size potential but faced major challenges from reproductive disorders and early removal. First-parity litter size strongly affected second-parity syndrome and sow stayability, highlighting the need for careful management of gilts with extreme first litters to improve retention and long-term productivity.
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Conflict of interest statement The authors have no conflicts of interest.