Lifetime sow productivity is influenced by both body protein and body fat reserves after first-litter weaning

Sow longevity and lifetime productivity is a key factor in determining herd productivity and lowering production costs. Sow replacement rates are high in Australia, with an average of 59% sow turnover (Benchmarking Report 2015, R. Campbell, pers. comm.) and the trends do not indicate any improvement. The main cause of sow turnover includes low litter size and reproductive failure, with many sows being culled prematurely. Hughes et al. (2010) suggested management practices that reduce sows entering the herd with excessive body reserves and are too heavy, would promote sow longevity. This study tested the hypothesis that sow longevity and lifetime performance is affected by body reserves in young sows.

In a study herd of 1637 weaned, Parity 1, first-cross sows (Large White × Landrace, PrimeGro Genetics™, Corowa, NSW, Australia), body reserves of protein and fat at mating following first litter weaning (Parity 1) were determined based on predictive equations (Smits et al. 2017). Sows were ranked independently for body protein and fat at Parity 1 mating as the lowest 25%, (LOW, n = 409), median 50% (MED, n = 819), and the highest 25% (HIGH, n = 409) cohort. The effects (mean ± s.e.) of body protein or fat cohort at mating on lifetime performance were determined by one-way GLM univariate ANOVA (SPSS v21.0, IBM, Armonk, NY, USA) using body fat or body protein mass, respectively, as a linear covariate. Data excludes any sow culled or removed before mating as a Parity 1 sow. Sows ranked with a HIGH body protein mass, adjusted to a constant body fatness, produced fewer litters and less piglets (P < 0.05) in their lifetime compared to sows with LOW or MED body protein reserves (Table 1). There was a minimal level of body fat reserves associated with lifetime performance, with MED or HIGH fat reserves, adjusted to a constant body protein, producing more piglets and lasting longer in the herd (LOW fat v. HIGH fat; P = 0.053). These results differ to other publications (Clowes et al. 2003), and this could be due to different genetics and feeding regimens resulting in sows with different protein and fat masses between studies.

Table 1.  The effect of sow body protein and fat mass at Parity 1 mating on lifetime sow performance

In conclusion, our data provides evidence that sows with body protein not exceeding 26 kg, and body fat mass no less than 41 kg, last longer and are more productive than large lean sows. Furthermore, we suggest that breeding sows need to be individually fed throughout life so that body reserves, particularly fat levels, can be maintained as suggested by Bunter et al. (2010).