Genetic study of litter size and litter uniformity in Landrace pigs

Abstract

Breeding and geneticsFull-length research article Genetic study of litter size and litter uniformity in Landrace pigs ABSTRACT -We aimed to estimate litter size and litter uniformity genetic parameters and genetic trends of Landrace pigs at birth and at three weeks by using multitrait analyses for 2,787 litters. The following litter traits were evaluated: number of piglets born alive (NBA), within-litter weight mean at birth (MBW), within-litter weight standard deviation at birth (SDB), within-litter weight coefficient of variation at birth (CVB), number of piglets at three weeks (NT), within-litter weight mean at three weeks (MT), within-litter weight standard deviation at three weeks (SDT), and within-litter weight coefficient of variation at three weeks (CVT). Heritability estimates for NBA, MBW, SDB, and CVB were 0.09±0.04, 0.31±0.08, 0.01±0.04, and 0.07±0.05, respectively, greater than those obtained at three weeks (0.06±0.04, 0.10±0.06, 0.01±0.04, and 0.02±0.04 for NT, MT, SDT, and CVT, respectively). The genetic correlations between NBA and MBW and between MBW and CVB (−0.73±0.20 and −0.93±0.21, respectively) were of moderate to high magnitudes, as well as the genetic correlations between CVT and SDT (0.85±0.39). Genetic correlations between MBW and MT, SDB and SDT, CVB and CVT, and NBA and NT were 0.73±0.16, 0.69±0.54, 0.36±0.80, and 0.95±0.06, respectively. The genetic trends were linear for NBA and CVB and quadratic for MBW and SDB, whereas for all traits at three weeks, they were close to zero. Within-litter weight coefficient of variation (CV) may be the most appropriate variation measure for application in breeding programs, especially at birth, due to its greater heritability estimate and high and negative genetic correlation with MBW. The genetic trends show that NT does not follow the increase in NBA, emphasizing the need to review the breeding goals.

Relationship between litter size at birth and within‐litter birth weight characteristics in laboratory mice as pilot animal for pig

“…(2006) estimated the phenotypic correlations of NBA to be 0.928 with LWB and –0.446 with MWB in mice originated from a three‐way cross of three inbred straits (Balb/c, C57BL, and CBA). Previous studies in pigs also estimated positive phenotypic correlations between NBA and LWB and negative phenotypic correlation between NBA and MWB (Banville et al., 2014; Bergsma et al., 2008; Camargo et al., 2020; Kapell et al., 2011; Matheson et al., 2018; Ogawa et al., 2019a; Wolf et al., 2008; Zhang et al., 2016). Correlations of NBA with MaxIWB and MinIWB were weakly negative and that with Range was weakly positive, in agreement with Wolf et al.…”

“…However, the standard errors were not small. Most previous studies in pig estimated the genetic correlation between NBA and SDIWB to be positive (Banville et al., 2014; Camargo et al., 2020; Damgaard et al., 2003; Kapell et al., 2011; Matheson et al., 2018; Wolf et al., 2008). Wolf et al.…”

“…Previous studies in pigs reported estimated phenotypic correlations between NBA and SDIWB with the absolute values of <0.2 (Banville et al, 2014;Bergsma et al, 2008;Camargo et al, 2020; F I G U R E 3 Standard normal quantile-quantile plots of the values of phenotypic measurements of traits. See Table 2for abbreviations of trait names.…”

“…Damgaard et al (2003) suggested using the standard deviation (SD) of within-litter BW (SDIWB) in selection as a dam trait to improve piglet growth and mortality from birth to weaning and within-litter homogeneity of weaning weight. Previous studies have estimated the genetic correlation of SDIWB with NBA, LWB, and MWB (Banville et al, 2014;Bergsma et al, 2008;Camargo et al, 2020;Canario et al, 2010;Damgaard et al, 2003;Kapell et al, 2011;Matheson et al, 2018;Wolf et al, 2008;Zhang et al, 2016). They estimated the heritabilities of these traits and their genetic and phenotypic correlations with NBA, LWB, and traits related to piglet loss until weaning, and proposed selection for higher MinIWB to reduce piglet loss at birth.…”

“…(2003) suggested using the standard deviation ( SD ) of within‐litter BW (SDIWB) in selection as a dam trait to improve piglet growth and mortality from birth to weaning and within‐litter homogeneity of weaning weight. Previous studies have estimated the genetic correlation of SDIWB with NBA, LWB, and MWB (Banville et al., 2014; Bergsma et al., 2008; Camargo et al., 2020; Canario et al., 2010; Damgaard et al., 2003; Kapell et al., 2011; Matheson et al., 2018; Wolf et al., 2008; Zhang et al., 2016).…”