Impact of Non-Confinement Accommodation on Farrowing Performance: A Systematic Review and Meta-Analysis of Farrowing Crates Versus Pens

Abstract

There are conflicting reports regarding the effect of farrowing house accommodation on piglet performance. The aim of this investigation was to use a systematic review and meta-analyses to summarise the results of publications that focused on direct comparisons between full confinement conventional crates and various designs of loose-housed farrowing pens from loading until weaning. Literature searches in Scopus, BIOSIS Previews, Cab Abstracts, and Web of Science identified 6695 articles. Twenty-two publications were retained for the systematic review and individual meta-analyses after screening for inclusion criteria. The random effects meta-analyses were performed on crate versus pen for number of piglets born alive, number of stillborn piglets, pre-weaning mortality, and number of piglets weaned. Additionally, the modifiers of confinement length (no confinement from loading until weaning or partial confinement for shorter periods of time in the early stages post parturition), enrichment (no enrichment or enrichment provided), and pen size (small, medium, or large) were examined. There was a 14% increase in the relative risk of piglet mortality in farrowing pens when they were compared with crates (p = 0.0015). The number of stillborns per litter was not different between the pen and crate. However, when providing enrichment in the pens, there was an increase in stillborns within farrowing crates versus pens (p = 0.009). There was no overall effect on piglets that were born alive or number weaned. As there is no difference between piglets born alive and mortality is significantly higher in farrowing pens, a reduction in the number of piglets weaned was expected but not observed, which was possibly due to the lack of weaning details provided in the publications. This was the first systematic review and meta-analysis conducted on the performance of farrowing accommodation and identified that farrowing pens do compromise post-natal piglet survival. Future efforts should focus on improving sow comfort in the farrowing crate to maximize both piglet and sow welfare.

Keywords: farrowing accommodation; farrowing pen design; meta-analysis; non-confinement; piglet mortality; sow; stillborn; systematic review.

Figure 1

A flow diagram documenting the process of identification and screening of eligible publications for inclusion in the systematic review and meta-analysis of non-confinement farrowing accommodation design. The flow chart was adapted from [16].

Figure 2

Forest plot of piglet mortality displaying relative risk for all articles are presented with 95% confidence interval. Each line represents an article or individual comparison between a farrowing crate and a farrowing pen alternative. A relative risk greater than 1 indicates increased likelihood of the piglet mortality being achieved in a farrowing crate relative to farrowing pen.

Figure 3

Funnel plot for all publications included in meta-analysis of total piglet mortality (n = 30). Grey areas indicate publications of significance, the dotted line represents the relative risk of 1 shown by a line of no-effect and white areas show non-significance. If no publication bias is present, the data-points will be organized symmetrically.

Figure 4

Forest plot of number of stillborn piglets displaying relative risk for all articles is presented with 95% confidence interval. Each line represents an article or individual comparison between a farrowing crate and a farrowing pen alternative. A relative risk greater than 1 indicates increased likelihood of stillborn piglets being achieved in farrowing crates relative to farrowing pens.

Figure 5

Funnel plot for all publications included in meta-analysis of number of stillborn piglets (n = 27). Grey areas indicate publications of significance, the dotted line represents the relative risk of 1 shown by a line of no-effect and white areas show non-significance. If no publication bias is present, the data-points will be organized symmetrically.

Figure 6

Standardized mean difference (SMD) for all articles are presented with 95% confidence interval. Each line represents an article or individual comparison between a farrowing crate and a farrowing pen alternative. A SMD greater than 1 indicates increased likelihood of born alive piglets being achieved in farrowing pens when compared to farrowing crates.

Figure 7

Standardised mean difference (SMD) for all articles are presented with 95% confidence interval. Each line represents an article or individual comparison between a farrowing crate and a farrowing pen alternative. A SMD greater than 1 indicates increased likelihood of wean number being achieved in farrowing pens when compared to farrowing crates.