Genetics of length of productive life and lifetime prolificacy in the Finnish Landrace and Large White pig populations1

Data on sow body weight (BW) and fatness (n 5 ,2250 pregnant sows) and reproductive data (including historical: n 5 ,18 000) were used to examine the genetic and phenotypic associations between body condition before and after farrowing, gestational outcomes, lactation feed intake and the gilts' ability to survive unculled to farrow in the second parity. Within-trait genetic correlations were very high between weight (0.77 6 0.06) and fat depth (0.91 6 0.04) recorded before farrowing and at weaning. Litter size traits were generally uncorrelated genetically with aspects of sow BW and body condition. However, genetic correlations indicated that sows producing heavier piglets at birth had litters with increased gain (0.36 6 0.16), and were characterised by greater weight (20.72 6 0.08) and fat change (20.19 6 0.15) during lactation, reflected to a lesser extent by lower weight (20.12 6 0.11) and fatness (20.17 6 0.10) at weaning. Genetic correlations (r a ) between reproductive traits and lactation feed intake were generally low, but favourable. However, lactation intake was positively correlated with measures of sow size (r a 5 ,0.55), such that selection for lactation feed intake would likely be accompanied by increased mature sow size. Phenotypic correlations (r p ) showed that sow survival to the second parity (FAR12) was positively influenced by litter size and fat depth at weaning, supporting attributes of increased fatness before farrowing, less weight loss during lactation and an increased lactation intake.

Section: Discussionsupporting

confidence: 69%

Body development in sows, feed intake and maternal capacity. Part 2: gilt body condition before and after lactation, reproductive performance and correlations with lactation feed intake

Lewis

Bunter

2011

“…Thus, a similar pre-mating phenotype may be arrived at in very different ways, and presumably this has implications for future gilt performance. This potentially explains the relatively poor predictive capacity of absolute finisher and post-finisher performance traits for sow longevity (Tholen et al, 1996b;Serenius and Stalder, 2004) or indeed lactation feed intake (Bunter et al, 2007b) at the phenotypic level, as there are substantial changes to individual sow phenotypes in the intervening period.…”

Section: Discussionmentioning

confidence: 99%

Body development in sows, feed intake and maternal capacity. Part 1: performance, pre-breeding and lactation feed intake traits of primiparous sows

Lewis

Bunter

2011

This study examined the genetic and phenotypic associations between finisher performance, pre-breeding body condition of the gilt, subsequent lactation feed intake and survival of the primiparous sow to farrow in the second parity. Complete data were available on ,2200 sows, along with additional cohort and historical performance data. Genetic variation was observed for average lactation feed intake (heritability: 0.18 6 0.04), with a significant proportion of observed variation in average intake attributable to variation in lactation length. Weight and body condition (fatness) at finishing were very highly correlated genetically (0.89 6 0.03 and 0.90 6 0.02) and moderately correlated phenotypically (0.58 6 0.01 and 0.58 6 0.01) with weight and body condition before mating. Estimates of genetic (r g ) and phenotypic (r p ) correlations between feed intake recorded at finishing and average lactation feed intake (LADI) were moderate (r g 5 0.26 6 0.16 and 0.42 6 0.22) and low (r p 5 0.07 6 0.02 and 0.08 6 0.03), with r g dependent on the models and data subsets used for lactation intake. Non-unity genetic correlations imply that different genetic control mechanisms regulate feed intake during growth and lactation. Moderate genetic correlations between lactation feed intake with live weight (TWT) or growth rate (TADG) recorded at selection and live weight before mating (0.42 6 0.11, 0.42 6 0.11 and 0.37 6 0.15) were considerably higher than the corresponding phenotypic correlations for LADI with TADG or 29WT (0.09 6 0.02 and 0.08 6 0.02). Correlations between fatness at selection (TFAT) or mating (29FT) and LADI were negative but not significantly different from 0. Overall, these data suggest that there is exploitable genetic variation for feed intake during lactation, and that selection is possible if lactation feed intakes are recorded. However, genetic correlations suggest that early growth seems to be related to lactation feed intake capacity. There was generally no strong evidence that selection for lean growth potential in dam lines will substantially diminish sow lactation intake capacity as a correlated response.

“…These results highlighted the underlying link between leg conformation and both sow productivity and fertility and their influence on sow survivability. It is important to note that leg-conformation scores and specific leg defects did not influence sow survival under the DE-specific competing risk analysis, although the overall influence of leg conformation on sow longevity is well established in the literature (Lopez-Serrano et al, 2000;Serenius and Stalder, 2004;Tarré s et al, 2006a;Fernà ndez Competing risk analyses in Duroc sows de Sevilla et al, 2008). It should also be considered that mobility problems would make it more difficult for sows to access resources as well as show a sow's normal behavior under the European Union directive 2001/88/EC (mandatory on European farms from January 1, 2013), which requires farmers to keep sows in group housing, from the 4th week of pregnancy until 1 week before farrowing.…”

mentioning

confidence: 95%

“…Leg and teat conformation Under the general model, overall leg-conformation score influenced sow longevity in LP and LF-specific analyses, as described by Lopez-Serrano et al (2000), Serenius andStalder (2004), Tarré s et al (2006a) and Fernà ndez de Sevilla et al (2008) for overall sow survival. Note that longevity records from sows culled due to severe leg-conformation problems were treated as censored in these analyses (less than 20% of sows showed a bad leg conformation after the first and second farrowings), and even so, leg conformation had a relevant influence on LP and LF culling.…”

mentioning

confidence: 99%

Competing risk analyses of longevity in Duroc sows with a special emphasis on leg conformation

Sevilla

Fàbrega

Tibau

et al. 2009

A competing risk approach was used to evaluate the influence of several factors on culling risk for 587 Duroc sows. Three different analyses were performed according to whether sow failure was due to death during productive life (DE) or to one of two causes for voluntary culling: low productivity (LP) and low fertility (LF). Sow survival was analyzed by the Cox model. Year at first farrowing (batch effect) significantly affected sow survival in all three analyses ( P , 0.05 for DE and P , 0.001 for LP and LF) whereas farm of origin accounted for relevant variation in the LP and LF analyses. LP culling increased with backfat thickness of more than 19 mm at the end of the growth period ( P , 0.05), bad teat condition ( P , 0.05) and reduced piglets born alive ( P , 0.001). For the LF competing risk analysis, culling increased with age at first farrowing ( P , 0.1). Special emphasis was placed on the influence of leg and teat conformation on sow survivability, although they did not affect sow failure due to DE ( P . 0.1). The overall leg-conformation score significantly influenced sow longevity in LP ( P , 0.001) and LF competing risk analyses ( P , 0.001), showing a higher hazard ratio (HR) for poorly conformed sows (1.013 and 4.366, respectively) than for well-conformed sows (0.342 and 0.246, respectively). Survival decreased with the presence of abnormal hoof growth in LP and LF analyses (HR 5 3.372 and 6.002, respectively; P , 0.001) and bumps or injuries to legs (HR 5 4.172 and 5.839, respectively; P , 0.01). Plantigradism reduced sow survival in the LP analysis ( P , 0.05), while sickle-hooked leg ( P , 0.05) impaired sow survival in the fertility-specific analysis. Estimates of heritability for longevity related to LP culling ranged from 0.008 to 0.024 depending on the estimation procedure, whereas heritability values increased to between 0.017 and 0.083 in LF analysis. These analyses highlighted substantial discrepancies in the sources of variation and genetic background of sow longevity depending on the cause of failure. The estimated heritabilities suggested that direct genetic improvement for sow longevity seemed feasible, although only a small genetic progress was expected.