Characteristics of repeat-breeding female pigs on southern EU commercial farms

A repeat-breeding (RB) occurrence increases non-productive days of female pigs (NPD), and consequently decreases herd productivity. However, characteristics of RB female pigs are not well defined or studied in swine. Also, few studies have compared lifetime reproductive performance between RB and non-RB female pigs. Our objectives were 1) to define and characterize RB occurrences using data from commercial farms in southern EU, 2) to examine factors associated with the RB risk, and 3) to assess the reproductive performances of the RB or non-RB females.

The data included 121,103 lifetime records and 645,103 service records of female pigs on 125 farms between 2008 and 2013. Applying the definition of RB in cattle to female pigs, an RB female pig was defined as a pig that had had three or more returns, or a pig that was culled due to reproductive failure after its second return within the same parity. The farms were classified into high-, intermediate- and low-performing farms on the basis of the upper and lower 10th percentile of the farm means of annualized lifetime pigs weaned per sow. Multilevel generalized linear models with random intercept were applied to the data. A chi-square test was also used to compare the frequency distributions (%).

Mean RB risks per service for female pigs (± SEM) was 0.5 ± 0.01%. Risks of RB in parities 0, 1 and 2 female pigs were 0.8, 0.5 and 0.4%, respectively, whereas risks of RB in parity 3 or later were only 0.2-0.3%. The RB female pigs had more regular returns, of 18-24 days post service, than non-RB female pigs (P < 0.05). Of 3,497 first re-service records of RB female pigs, 47% had regular returns. They also had increased lifetime NPD, ranging from 171 to 206 days, compared with only 78-84 days for non-RB females. Risk factors for RB pigs were low parity (i.e., 0 and 1), summer servicing, farrowing fewer number of pigs born alive and being in low-performing herds. However, gilt age at-first-mating (P=0.13), nor number of stillborn piglets (P=0.64), nor farm size for females (P = 0.08) were associated with RB. For instance, risk of RB in gilts and in summer were 1.5 and 0.8%, respectively, compared to only 0.3 and 0.6% in parity 6 or more and in winter. The RB risks on high-performing and lowperforming farms were 0.2 and 2.6%, respectively. The RB females had 55.2-92.5 more lifetime NPD, 1.5-3.3 lower parity at culling and 19.4-39.2 fewer lifetime pigs born alive across parities than non-RB females (P < 0.05).

We recommended that producers, especially on low-performing farms, should closely monitor the identified female pig groups at a greater risk of a having RB.

Disclosure of Interest: None Declared.