Correlated responses in sow appetite, residual feed intake, body composition, and reproduction after divergent selection for residual feed intake in the growing pig1

Abstract

Residual feed intake (RFI) has been explored as an alternative selection criterion to feed conversion ratio to capture the fraction of feed intake not explained by expected production and maintenance requirements. Selection experiments have found that low RFI in the growing pig is genetically correlated with reduced fatness and feed intake. Selection for feed conversion ratio also reduces sow appetite and fatness, which, together with increased prolificacy, has been seen as a hindrance for sow lifetime performance. The aims of our study were to derive equations for sow RFI during lactation (SRFI) and to evaluate the effect of selection for RFI during growth on sow traits during lactation. Data were obtained on 2 divergent lines selected for 7 generations for low and high RFI during growth in purebred Large Whites. The RFI was measured on candidates for selection (1,065 pigs), and sow performance data were available for 480 sows having from 1 to 3 parities (1,071 parities). Traits measured were sow daily feed intake (SDFI); sow BW and body composition before farrowing and at weaning (28.4 ± 1.7d); number of piglets born total, born alive, and surviving at weaning; and litter weight, average piglet BW, and within-litter SD of piglet BW at birth, 21 d of age (when creep feeding was available), and weaning. Sow RFI was defined as the difference between observed SDFI and SDFI predicted for sow maintenance and production. Daily production requirements were quantified by litter size and daily litter BW gain as well as daily changes in sow body reserves. The SRFI represented 24% of the phenotypic variability of SDFI. Heritability estimates for RFI and SRFI were both 0.14. The genetic correlation between RFI and SRFI was 0.29 ± 0.23. Genetic correlations of RFI with sow traits were low to moderate, consistent with responses to selection; selection for low RFI during growth reduced SDFI and increased number of piglets and litter growth, but also increased mobilization of body reserves. No effect on rebreeding performance was found. Metabolic changes previously observed during growth in response to selection might explain part of the better efficiency of the low-RFI sows, decreasing basal metabolism and favoring rapid allocation of resources to lactation. We propose to consider SRFI as an alternative to SDFI to select for efficient sows with reduced input demands during lactation.

Genetic parameters for thermoregulation and production traits in lactating sows reared in tropical climate

“…Repeatability estimates were low to high for lactating performance traits and for thermoregulation traits (>0.36) because of strong permanent environmental effect for some traits such as ADFI or RR. The heritability estimate of ADFI (0.26 ± 0.08) was in agreement with estimates obtained in studies performed in temperate conditions such as for commercial crossbred sows reared in the Netherlands (h 2 between 0.19 and 0.27; Bergsma and Hermesch, 2012), or for purebred Large White lines reared in France (h 2 = 0.26 ± 0.07; Gilbert et al, 2012). However, the estimate of heritability of ADFI of our study is greater than the weighted mean of heritability estimates of ADFI (0.08 ± 0.04) obtained in commercial mainstream breeds in the tropics from meta-analysis performed by Akanno et al (2013).…”

“…The heritability estimate of sow proportion of BW change during lactation (0.20 ± 0.07) was in accordance with the 0.20 heritability estimate of sow BW change score reported in Rydhmer's review (2000) or BW losses (in kilogram) reported by Bergsma et al (2008). These values are slightly lower than the 0.13 ± 0.05 heritability estimate of change of BW of the sow during lactation reported by Gilbert et al (2012).…”

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

“…The heritability estimated for LW in the present study (h 2 = 0.22, PSD = 0.05) is comparable to previously published reports about preweaning growth traits in other populations (Högberg and Rydhmer, 2000;Bergsma et al, 2008) and previous estimates from the studied Norwegian Landrace population Lundgren et al, 2012), but higher than the heritability for litter weight at 3 weeks (h 2 = 0.09), recently estimated by Gilbert et al (2012).…”

“…The estimated heritabilities for appetite during the first 3 weeks (APP; h 2 = 0.07, PSD = 0.03) and for feed intake at 3 weeks (FEED; h 2 = 0.06, PSD = 0.03) were, however, lower than estimates previously presented in the literature. Bergsma et al (2008) estimated the heritability for voluntary feed intake during the whole lactation period at 0.30, Gilbert et al (2012) at 0.26 and Bergsma et al (2013) at 0.23. Bunter et al (2010) reported a heritability of average lactation feed intake at 0.15, and Hermesch et al (2010) estimated the heritability at 0.10 during early lactation (5 to 14 days).…”

“…The body resources available for production and reproduction are limited and there is a trade-off between different biological processes such as investment in maintenance, own growth, reproduction or growth, and survival of offspring (Rauw, 2009). Gilbert et al (2012) selected growing pigs for low or high residual feed intake and compared sows from the two lines. In generation 7, the low RFI-sows (i.e.…”