The genetic foundation of fitness and reproduction traits in Australian pig populations. 2. Relationships between weaning to conception interval, farrowing interval, stayability, and other common reproduction and production traits.

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: 93%

Section: Discussionsupporting

confidence: 74%

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

“…In this study, there was some support for such a relationship, but the estimates were imprecise (r g LW-WSI7 = 0.43, PSD = 0.23; r g LW-WSI50 = 0.33, PSD = 0.21). Tholen et al (1996) estimated the genetic correlation between litter weight at 21 days and weaning-toconception interval for 1st-parity sows to −0.09. Bergsma et al (2008) found an unfavourable but not significant genetic correlation (0.15) and a phenotypic correlation close to zero between litter weight gain and prolonged interval.…”

Section: Correlationsmentioning

confidence: 99%

Genetic parameters for feed intake, litter weight, body condition and rebreeding success in primiparous Norwegian Landrace sows

Lundgren

Fikse

Grandinson

et al. 2014

The aim of this study was to estimate genetic parameters for feed intake recorded as farmers' perception of young sows' appetite for the first 3 weeks of lactation (APP) and feed intake recorded for one day in the 3rd week of lactation (FEED), litter weight (LW) at 3 weeks, sow body condition at weaning (BC) and the following five reproduction traits: weaning-to-service interval of 1 to 7 days (WSI7), weaning-to-service interval of 1 to 50 days (WSI50), delayed service or not (DELAYED), pregnant on first service or not (PREGNANT) and litter size in 2nd parity (NBT2). The analyses included data on 4606 Norwegian Landrace 1st-parity sows and their litters. The Gibbs sampling method was used. The traits DELAYED and PREGNANT were analysed as threshold traits and APP, FEED, LW, BC, WSI7, WSI50 and NBT2 were analysed as linear traits. The heritability estimates for APP and FEED were low (<0.1), whereas the estimates for DELAYED and PREGNANT were rather high (0.4 and 0.3). The heritability estimate for BC was 0.2. The genetic correlations confirmed the complexity of breeding for sow performance; selection for heavy 1st litters may lead to lower body condition at weaning, which in turn leads to lower reproductive performance and smaller litters in 2nd parity. Selection for higher sow feed intake would improve body condition, but the simple way of measuring feed intake tested in this study (APP and FEED) cannot be recommended because of the low heritability obtained for these traits.

“…Considering that pre-farrowing body composition is thought to be an important factor for both sow longevity (Tholen et al, 1996b) and piglet mortality (Grandinson et al, 2005), and sow condition before mating can have a significant effect on condition before parturition (Guillemet et al, 2006), it is important that these associations are explored.…”

Section: Discussionmentioning

confidence: 99%

“…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.