Traits Of Sows Research Articles

Factors affecting length of productive life and lifetime production traits in a commercial swine herd in Northern Thailand

The length of productive life (LPL) and lifetime production traits are economically important in commercial swine production systems. This study investigated factors that may influence the LPL and lifetime production traits of sows in a commercial swine population in Thailand. The dataset consisted of information from 2768 sows that had their first farrowing from 1989 to 2012. Three breed groups of sows were represented: 122 Duroc, 1944 Landrace and 702 Yorkshire. The traits analyzed were the LPL, lifetime piglets born alive (LBA), lifetime piglets weaned (LPW), lifetime piglets birth weight (LBW) and lifetime piglets weaning weight (LWW). The model consisted of year-season of first farrowing, breed group and age at first farrowing as fixed effects and the residual as a random effect. Year-season of first farrowing was an important source of variation for all traits (p < 0.0001). Yorkshire sows had the longest LPL (p < 0.05) and the highest LPW (p < 0.05) of all sow breed groups, whereas Duroc sows had the lowest least squares means for all traits. Landrace and Yorkshire sows had similar LBA, LBW and LWW. Thus, Yorkshire sows had the highest production efficiency (the longest LPL and highest LPW) of the three breed groups in this population. Age at first farrowing was negatively associated with LPL, LBA, LPW, LBW and LWW. The favorable association between age at first farrowing with LPL and LPW could be used to increase the efficiency of swine production in this population.

Suckling strategies in the pig: The Göttingen minipig as a model

Göttingen minipig (GMP) has gained importance as model animal in human medicine. However, little is known about the suckling behaviour of GMP. Suckling is considered as a fundamental behavioural trait in mammals, most important for development and survival of the individual. Understanding its development and changes due to artificial selection is important when planning selection on reproductive traits in sows. GMP is a highly valuable model for studying the suckling behaviour in the pig, because its key features are intermediate between commercial breeds (CB) and wild boar (WB), namely, similar teat number as CB, similar litter size as WB and balanced muscularity of extremities. We compared the suckling behaviour of GMP and CB based on measures of suckling stability (the probability of consecutive sucklings on the same suckling position), suckling ranges (number of teat pairs in the range of the outermost teat pairs that piglets occupied) and piglets’ distribution along the udder by use of the MDE-model (effect of geometric constraints, normally expressed as a hump-shaped distribution of organisms). We also incorporated published date on suckling preferences of WB piglets. Our study revealed alterations of suckling behaviour in piglets, wherein GMP showed intermediate suckling strategies (i.e. suckling ranges). However, there appeared to be a certain degree of behavioural conservatism. Domestic piglets maintained the tendency to prefer abdominal (middle) teats, which are anatomically posterior in WB and preferred by wild piglets. It can be suggested, that this general tendency seen in domestic piglets (GMP and CB), is not generated by geometric constraints (mid-domain effect), but appears to originate from the wild ancestor. Results of the present study suggest that the selection of CB for increasing litter size and higher number of teats might have led to imbalances between suckling behaviour, teat number and udder space availability.

Estimation of Genetic Parameters and Trends for Length of Productive Life and Lifetime Production Traits in a Commercial Landrace and Yorkshire Swine Population in Northern Thailand.

The objective of this research was to estimate genetic parameters and trends for length of productive life (LPL), lifetime number of piglets born alive (LBA), lifetime number of piglets weaned (LPW), lifetime litter birth weight (LBW), and lifetime litter weaning weight (LWW) in a commercial swine farm in Northern Thailand. Data were gathered during a 24-year period from July 1989 to August 2013. A total of 3,109 phenotypic records from 2,271 Landrace (L) and 838 Yorkshire sows (Y) were analyzed. Variance and covariance components, heritabilities and correlations were estimated using an Average Information Restricted Maximum Likelihood (AIREML) procedure. The 5-trait animal model contained the fixed effects of first farrowing year-season, breed group, and age at first farrowing. Random effects were sow and residual. Estimates of heritabilities were medium for all five traits (0.17±0.04 for LPL and LBA to 0.20±0.04 for LPW). Genetic correlations among these traits were high, positive, and favorable (p<0.05), ranging from 0.93±0.02 (LPL-LWW) to 0.99±0.02 (LPL-LPW). Sow genetic trends were non-significant for LPL and all lifetime production traits. Sire genetic trends were negative and significant for LPL (−2.54±0.65 d/yr; p = 0.0007), LBA (−0.12±0.04 piglets/yr; p = 0.0073), LPW (−0.14±0.04 piglets/yr; p = 0.0037), LBW (−0.13±0.06 kg/yr; p = 0.0487), and LWW (−0.69±0.31 kg/yr; p = 0.0365). Dam genetic trends were positive, small and significant for all traits (1.04±0.42 d/yr for LPL, p = 0.0217; 0.16±0.03 piglets/yr for LBA, p<0.0001; 0.12±0.03 piglets/yr for LPW, p = 0.0002; 0.29±0.04 kg/yr for LBW, p<0.0001 and 1.23±0.19 kg/yr for LWW, p<0.0001). Thus, the selection program in this commercial herd managed to improve both LPL and lifetime productive traits in sires and dams. It was ineffective to improve LPL and lifetime productive traits in sows.

Genetic association between leg conformation in young pigs and sow longevity.

Longevity is important in pig production with respect to both economic and ethical aspects. Direct selection for longevity might be ineffective because 'true' longevity can only be recorded when a sow has been culled or died. Thus, indirect selection for longevity using information from other traits that can be recorded early in life and are genetically correlated with longevity might be an alternative. Leg conformation has been included in many breeding schemes for a number of years. However, proving that leg conformation traits are good early indicators for longevity still remains. Our aim was to study genetic associations between leg conformation traits of young (5months; 100kg) Swedish Yorkshire pigs in nucleus herds and longevity traits of sows in nucleus and multiplier herds. Data included 97533 animals with information on conformation (Movement and Overall score) recorded at performance testing and 26962 sows with information on longevity. The longevity traits were as follows: stayability from 1st to 2nd parity, lifetime number of litters and lifetime number of born alive piglets. Genetic analyses were performed with both linear models using REML and linear-threshold models using Bayesian methods. Heritabilities estimated using the Bayesian method were higher than those estimated using REML, ranging from 0.10 to 0.24 and 0.07 to 0.20, respectively. All estimated genetic correlations between conformation and longevity traits were significant and favourable. Heritabilities and genetic correlations between conformation and longevity indicate that selection on leg conformation should improve sow longevity.

Genetic and environmental factors affecting reproductive traits in sows in an outdoor production system

The aim of this study was to characterize the genetic (crossbreeding and additive genetic) and environmental factors affecting reproduction of sows on an outdoor production system. Data from the Experimental Swine Unit of Facultad de Agronomía, Progreso, Uruguay, were used. The breeding herd included purebred Pampa Rocha (P) and Duroc (D), as well as hybrid (H: P×D and D×P) sows. Pampa Rocha is considered the only local swine breed of Uruguay. The dataset contained 1309 litter records from 197 sows (136 P, 22 D and 39 H) collected from 1997 to 2011. Feeding was based on grazing, restricting the use of concentrate to the breeding herd. The variables analysed were: number of piglets born alive (PBA), average piglet weight of the litter at birth (ABW), number of piglets weaned (PW), average piglet weight of the litter at weaning (AWW), survival from birth to weaning (S) and weaning-to-conception interval (WCI). The following fixed factors were included in the final model: year of farrowing, time of the year (month or season, depending on the variable analysed), inbreeding of the sow, parity number, weaning age, direct breed effects, individual heterosis, repeated measures on the sow (used to estimate the permanent environment effect), and the animal random effect. Duroc sows produced 1.1 more PBA (p=0.03) than P sows. Significant heterosis effects were found for PBA (0.88 piglets, p=0.009) and for PW (0.72 piglets, p=0.03). Hybrid sows produced 1.43 and 1.15 piglets more than P sows, and 0.33 and 0.29 piglets more than D sows, born alive and weaned, respectively. No differences in other variables between genotypes were found. Heritability values (SE) were 0.13 (0.06) for PBA, 0.31 (0.08) for ABW, 0.14 (0.06) for PW, 0.17 (0.02) for AWW, 0.10 (0.01) for S and 0.08 (0.03) for WCI. Winter and spring farrowings resulted in heavier piglets at birth (p<0.001) and at weaning (p<0.01), but no effect on PBA, P and S was observed. Weaning-to-conception interval was greater in summer months (p<0.001). The results suggest seasonal reproductive behaviour. The local breed (P) compared well with a conventional one (D). Furthermore, the crossbred dam appeared attractive due to heterosis in litter traits.

Wider stall space affects behavior, lesion scores, and productivity of gestating sows.

Limited space allowance within the standard gestation stall is an important welfare concern because it restricts the ability of the sow to make postural adjustments and hinders her ability to perform natural behaviors. Therefore, we evaluated the impacts of increasing stall space and/or providing sows the freedom to access a small pen area on sow well-being using multiple welfare metrics. A total of 96 primi- and multiparous crossbred sows were randomly assigned in groups of 4 sows/treatment across 8 replicates to 1 of 3 stall treatments (TRT): standard stall (CTL; dimensions: 61 by 216 cm), width-adjustable stall (flex stall [FLX]; dimensions: adjustable width of 56 to 79 cm by 216 cm), or an individual walk-in/lock-in stall with access to a small communal open-pen area at the rear of the stall (free-access stall [FAS]; dimensions: 69 by 226 cm). Lesion scores, behavior, and immune and productivity traits were measured at various gestational days throughout the study. Total lesion scores were greatest for sows in FAS and least for sows in FLX ( < 0.001). Higher-parity sows in FAS had the most severe lesion scores (TRT × parity, < 0.0001) and scores were greatest at all gestational days (TRT × day, < 0.05). Regardless of parity, sows in FLX had the least severe scores ( < 0.0001). As pregnancy progressed, lesion scores increased among sows in CTL ( < 0.05). Sow BW and backfat (BF) were greater for sows in FLX and FAS ( < 0.05), and BCS and BF were greater for parity 1 and 2 sows in FAS than the same parity sows in CTL (TRT × parity, < 0.05). Duration and frequency of some postural behaviors and sham chew behavior were affected by TRT ( < 0.05) and time of day (TRT × day, < 0.05). These data indicate that adequate stall space, especially late in gestation, may improve the well-being of higher-parity and heavier-bodied gestating sows as assessed by changes in postural behaviors, lesion severity scores, and other sow traits. Moreover, compromised welfare measures found among sows in various stall environments may be partly attributed to the specific constraints of each stall system such as restricted stall space in CTL, insufficient floor space in the open-pen area of the FAS system, and gate design of the FLX (e.g., direction of bars and feeder space). These results also indicate that parity and gestational day are additional factors that may exacerbate the effects of restricted stall space or insufficient pen space, further compromising sow well-being.

Leukemia Inhibitory Factor (&lt;i&gt;LIF&lt;/i&gt;) Gene Polymorphism and its Impact on Reproductive Traits of Pigs

The purpose of this study was to determine the frequencies of alleles and genotypes of the Leukemia Inhibitory Factor (LIF) gene (ID: 399503) in Landrace, Large White and Duroc pigs in Russia and to evaluate the impact on productive traits of pigs. Polymorphism was genotyped using PCR-RFLP method. In the course of studies we observed a different distribution of allele and genotype frequencies of different breeds. In all breeds under study all three genotypes AA, AB, BB were determined. The results of this study suggest that the LIF gene promotes the reproductive traits of pigs. The AA genotype sows compared to BB genotype analogues have better Total Number of Born (TNB) and Number Born Alive (NBA) by 1.4 and 1.3 (p<0.01) in Landrace sows, 1.3 and 0.9 (p<0.05) in Large White and 2.0 and 3.3 (p<0.001) in Duroc, respectively. The AB genotype sows exhibit intermediate values, which testifies the concentration of a favorable A allele in the pig genotype of animals contributing to the fertility. Our research revealed a positive effect of A allele and AA genotype that indicates the possibility to use this polymorphism in improving reproduction traits of sows.

Economic weights for maternal traits of sows, including sow longevity1

The objective of this study was to develop a transparent, comprehensive, and flexible model for each trait for the formulation of breeding objectives for sow traits in swine breeding programs. Economic values were derived from submodels considering a typical Australian pig production system. Differences in timing and expressions of traits were accounted for to derive economic weights that were compared on the basis of their relative size after multiplication by their corresponding genetic standard deviation to account for differences in scale and genetic variability present for each trait. The number of piglets born alive had the greatest contribution (27.1%) to a subindex containing only maternal traits, followed by daily gain (maternal; 22.0%) and sow mature weight (15.0%). Other traits considered in the maternal breeding objective were preweaning survival (11.8%), sow longevity (12.5%), gilt age at puberty (8.7%), and piglet survival at birth (3.1%). The economic weights for number of piglets born alive and preweaning piglet survival were found to be highly dependent on the definition of scale of enterprise, with each economic value increasing by approximately 100% when it was assumed that the value of extra output per sow could be captured, rather than assuming a consequent reduction in the number of sows to maintain a constant level of output from a farm enterprise. In the context of a full maternal line index that must account also for the expression of direct genetic traits by the growing piglet progeny of sows, the maternal traits contributed approximately half of the variation in the overall breeding objective. Deployment of more comprehensive maternal line indexes incorporating the new maternal traits described would lead to more balanced selection outcomes and improved survival of pigs. Future work could facilitate evaluation of the economic impacts of desired-gains indexes, which could further improve animal welfare through improved sow and piglet survival. The results justify further development of selection criteria and breeding value prediction systems for a wider range of maternal traits relevant to pig production systems.

Genetic Parameters and Genetic Gain for the Reproduction Traits in Latvian Landrace and Yorkshire Sows Populations

The aim of this study was to estimate genetic parameters for the reproduction traits of Landrace and Yorkshire sows and to analyze the genetic gain in these Latvian swine populations. Records of 14 577 first-parity and 27 359 later-parities Landrace sows and 6039 first-parity and 12 360 later-parities Yorkshire sows born between 2000 and 2012 were included in the analysis. The number of piglets born alive and 21-day litter weight at first and later parities, and weaning–conception interval between the first and second parity were included in the study. The genetic parameters were estimated using a single-trait animal model for the first parity and a single-trait repeatability animal model for later parities using REML procedure. Compared to heritability estimates for number born alive, heritabilities for litter weight were higher in both populations: in the first parity 0.10±0.015 vs. 0.31±0.021 for Landrace, and 0.05±0.016 vs. 0.23±0.028 for Yorkshire; in later parities 0.10±0.010 vs. 0.23±0.013 for Landrace, and 0.10±0.017 vs. 0.20±0.022 for Yorkshire. The heritability of reproduction traits was low; however, during the last ten years, reproduction traits in nucleus herds were improving. The results show that genetic progress in the last five years has been relatively low.

Discovery of two potential DAZL gene markers for sperm quality in boars by population association studies

The Deleted in AZoospermia Like (DAZL) gene is a member of the DAZ (deleted in azoospermia) gene family which are critical for successful germ cell development in diverse animals. In previous research, we discovered two SNPs (DAZL c.570+385 A>G, DAZL c.735+150 C>A) associated with litter size traits in sows. Here we selected DAZL gene as a candidate gene for boar sperm quality traits based on its function on the formation of germ cells during spermatogenesis, and then analyzed the associations of the two SNPs with sperm quality traits in Duroc (n=185), Large White (n=87) and Landrace (n=49) pig populations. The results showed DAZL c.570+385 AG boars had significantly higher motility (MOT) than GG boars (P<0.05) in Large White and Landrace pigs; Duroc DAZL c.735+150 CA boars had significantly lower MOT and lower sperm concentration (SCON) than CC and AA boars (P<0.05), respectively; Large White DAZL c.735+150 CC boars produced lower abnormal sperm rate (ASR) than CA and AA boars (P<0.05), with favorable allelic C substitution effect −0.94% (P<0.05). Our research indicated that DAZL c.570+385 A>G and DAZL c.735+150 C>A locus were the potential molecular markers for improving the sperm quality traits in pigs.

Association study between single nucleotide polymorphisms in candidate genes and reproduction traits in Italian Large White sows

In this study we evaluated the effects of candidate single nucleotide polymorphisms (SNPs) on reproduction traits of Italian Large White (ITLW) purebred sows at first parity. We genotyped DNA samples extracted from hair roots of 1,548 sows distributed across six farms located in Northern Italy. A total of 21 SNPs in 20 genes, selected from literature, were genotyped. Seventeen SNPs showed minor allele frequencies >0.05 in the ITLW breed. Association analyses were performed with the following traits: number of piglets born alive (NBA1), number of stillborn piglets (NSB1), total number born (TNB1), NBA1 estimated breeding values (EBVs) and NBA1 random residuals (RRs). SNPs in BMPR1B, FUT1, GPX5, RBP4 and TGFBR1 genes showed significant association (P nominal <0.003) with NBA1 EBVs. Additional three markers (EPOR, GDF9:c.1806T>C and STAT5B) presented suggestive effects (P nominal <0.03) on NBA1 EBVs. The BMPR1B SNP showed a trend (P nominal from 0.01 to 0.05) on NBA1, NBA1 RRs and TNB1. This gene could be a promising candidate for additional investigations aiming to confirm evidences reported in this study.

Polymorphisms of the osteopontin gene and level of its expression in the reproductive tract of sows / Polimorfizm w genie osteopontyny i poziom jej ekspresji w układzie rozrodczym loch

AbstractThe aim of the study was to find osteopontin gene (OPN) polymorphisms as potential mutations affecting the expression level of genes in the ovaries, uterus and oviduct of sows. The material consisted of 71 F1 sows (Polish Large White × Polish Landrace). In the first stage several polymorphisms in the promoter region, intron 6, exon 6 and 7 of the OPN gene were found. The parameters estimated were the frequency of alleles and genotypes, observed heterozygosity and gene diversity, PIC, and chi2 factors. Chi2 values allow for assessment of genetic equilibrium in the population. Thus, the loci OPNp3-4 and OPNe6-1 were in genetic disequilibrium while locus OPNe6-Knoll showed genetic equilibrium. Also real-time PCR analysis to determine the expression dynamics of the OPN gene in examined tissues was performed in relation to “housekeeping” genes. A comparison was made for relative expression in different tissues and different mutations. The highest expression pattern was observed in the oviduct. Based on the novel polymorphisms a significant correlation between the OPN genotype and OPN expression (mRNA) level in the ovary, oviduct, uterine body and uterine horn was observed. In the second stage, the levels of expression of the OPN gene in individual tissues, traits of reproductive performance and reproductive tract traits of sows were also compared. The expression levels in the uterine body and oviduct were related to the age of mating, cervical length, litter weight at birth, number of active nipples, age at slaughter and body weight at mating.

INFLUENCE OF THE PROLACTIN GENE POLYMORPHISM ON SELECTED REPRODUCTION TRAITS IN SOWS OF POLISH LARGE WHITE BREED

The objective of our analyses was to identify prolactin gene polymorphism and determine its effect on reproduction traits in sows. The research included 138 Polish Large White sows from four nucleus herds supervised by the Polish Pig Breeders and Producers Association “POLSUS” based in the kujawsko-pomorskie province. Molecular analyses were conducted using the PCR-RFLP method. Three PRL/TaaI genotypes and two alleles were found in the examined sows. The allele frequency was as follows: PRLIns – 0.50; PRLDel – 0.50, and the genotype frequency was at the following level: Del/Del – 0.27, Ins/Del – 0.45, Ins/Ins – 0.28. We determined the mean age at the first farrowing, and the mean number of piglets born alive and reared until 21 of their lives in two subsequent farrows. No statistically significant differences were found between the genotype variants within the analysed reproduction traits in Polish Large White pigs. The results we obtained prove that there is a need to continue research in this area using a larger group of animals.

Estimation of genetic and phenotypic parameters for sow productivity traits in South African Large White pigs

The objective of the study was to estimate genetic and phenotypic parameters for sow productivity traits of South African Large White pigs, using data from the Integrated Registration and Genetic Information Systems. The analyses were done on 29 719 records for 7 983 sows from 29 herds, which farrowed between 1990 and 2008. Data were analysed as a sow trait using a repeatability animal model. The traits analysed were number of piglets born alive (NBA), litter birth weight (LBWT), 21-day litter size (D21LS) and 21-day litter weight (D21LWT). Estimates of heritability for these traits were 0.07 ± 0.01, 0.11 ± 0.01, 0.03 ± 0.01 and 0.06 ± 0.01, respectively. The respective repeatability estimates for the traits were 0.15 ± 0.01, 0.16 ± 0.01, 0.11 ± 0.01 and 0.12 ± 0.01. Genetic correlations among the traits ranged from 0.32 ± 0.07 between NBA and D21LWT to 0.88 ± 0.04 between NBA and D21LS. The phenotypic correlations ranged from 0.35 ± 0.01 between NBA and D21LWT to 0.75 ± 0.01 between NBA and LBWT. Litter traits at birth were more heritable and repeatable than traits measured at 21 days of age. In general, all traits showed positive genetic and phenotypic trends for the period studied. The heritability of sow productivity traits was low and less repeatable, which suggests that response to selection may be slow and that the performance in the first parity may not always predict future performance. However, because of their economic importance, an attempt should always be made to keep these traits at their optimum.Keywords: Reproductive traits, pigs, genetic progress, phenotypic performance, correlations

The effect of a SNP in ESR gene on the reproductive performance traits in Polish sows

The aim of the experiment was to detect polymorphism in the ESR gene to determine associations between the genotype and litter size in Polish Large White and Landrace sows. Reproductive traits investigated were: total number of piglets born (TNB), number of piglets born alive (NBA) and number of piglets weaned (TW). The polymorphism in ESR gene was detected using the PCR-RFLP method, with specific primers and the restriction enzyme AvaI. Two different alleles of ESR gene were identified: alleles A (0.71) and B (0.29). The relationship between the ESR genotypes and TBN, NBA and NW were analyzed. The analysis showed in first parity sows statistically significant (P < 0.01) differences between sows carrying different ESR genotypes. The analysis of ESR gene showed that sows with BB genotype had the largest litter size compared to AB and BB sows, but the difference was statistically not significant.

Colostrum and milk production of sows is affected by dietary conjugated linoleic acid

The present experiment was conducted to investigate dietary effects of conjugated linoleic acid (CLA) on sow traits related to piglet survival and growth performance. A total of 23 gestating sows were fed either a standard lactation diet (control diet [CON]) or the CON supplemented with 1.3% CLA (cis-9, trans-11 and trans-10, cis-12) from day 108 of gestation until weaning (4 wk after parturition) to evaluate whether dietary CLA affects the yield and composition of colostrum, time for initiation of milk production, and sow milk yield. Sows fed CLA tended to produce more colostral fat (6.3 vs. 5.2%, respectively; P = 0.10) than CON sows whereas contents of lactose, protein, and dry matter were similar in the two groups. Sows fed CLA tended to produce less colostrum than CON sows (409 vs. 463 g/piglet, respectively; P = 0.07) as predicted by the piglet rate of gain from 0 to 24 h (58 vs. 97 g/piglet, respectively; P = 0.07). The piglet mortality during the first week of lactation tended to be higher for sows fed CLA than for CON sows (6.8 vs. 2.3%, respectively; P = 0.10), and the number of piglets that died or were moved to others sows to ensure survival during the first week was more than double in the CLA group (17.6 vs. 7.8%, respectively; P = 0.04). Copious milk production was initiated 33 h (CLA) and 34 h (CON) after parturition and was not affected by dietary treatments (P = 0.41). Sow milk yield was improved by the CLA treatment from days 7 to 14 of lactation (P = 0.03). Weight at birth (1.40 kg for both groups; P = 0.98) and at weaning [8.2 kg (CLA) and 8.0 kg (CON); P = 0.52] was not statistically different. In conclusion, colostrum yield was inhibited but milk yield was stimulated by dietary inclusion of cis-9, trans-11 and trans-10, cis-12 CLA and indicates that sow productivity may be improved by using different fatty acids for transition and lactating sows.

Genetic parameters including the service sire effect for the sow traits stillbirth and piglet losses in Czech Large White and Landrace

&amp;nbsp;Genetic parameters including the proportion of variance for the service sire effect were estimated for number of piglets stillborn (including piglets died until 24 h after birth) and number of piglets died from 24 h after birth until weaning in Czech Large White (89 231 litters) and Czech Landrace (28 320 litters) pigs. Both traits were considered to be traits of the sow. Two two-trait animal models were evaluated for each breed including or excluding the service sire effect. Estimates of genetic parameters were very similar for the two models. The heritability for number of stillborn piglets was 0.06 in both breeds and both models and the heritability for number of piglets died until weaning was 0.07 in Czech Large White and 0.05 to 0.06 in Czech Landrace. The proportion of variance due to service sire was very low (between 0.8 and 1.6%). Therefore, there is no need to include the service sire effect in models for genetic evaluation. A selection against farrowing losses is recommended though only a slow improvement of the trait can be expected. Selecting against piglets died until weaning seems to be cumbersome. Probably a selection on number of piglets weaned could be helpful in minimizing piglet losses until weaning. &amp;nbsp;

Polymorphism of the estrogen receptor 1 locus in populations of pigs of different genotypes and its association with reproductive traits of large white sows

Populations of Large White, Large Black, Poltava Meaty, Pietrian, and Meishan pigs are characterized by intron PvuII polymorphism in the estrogen receptor 1 gene (ESR1). These breeds differ in ESR1 alleles and genotypes frequencies. In the populations, there are deviations in the genotype distribution from the Hardy-Weinberg equilibrium. The established estrogen receptor 1 locus association with the reproductive traits of Large White sows indicates the possibility of using intron ESR1 PvuII polymorphism as a genetic pregnancies marker in pig selection.

Gilt development traits associated with genetic line, diet and fertility

The objective was to associate gilt development traits with genetic line, diet and fertility group (FG). Gilts (n=1225) were reared from 162 to 265 days of age at a gilt development unit (GDU) and sent to sow farms. Females were Landrace (L), Large White (LW), L and LW F1 or L and LW composite. Estrous traits included age at puberty (AGEPUB), length of estrus (LOE), maximum strength of standing reflex with (MSRBOAR) or without (MSRNOBOAR) a boar present, total strength of standing reflex with (TSRBOAR) or without (TSRNOBOAR) a boar present, vulva redness (VR), strength of vulva reddening and swelling (VISUAL VULVA) and vulva width (VW). Growth and body composition traits were puberty weight, days to 114kg and 10th rib backfat (BF) and loin muscle area (LMA) at 114kg and puberty. Structural conformation traits included muscle mass, rib width, front leg side view, rear leg side view, front legs front view, rear legs rear view and locomotion (LOC). Sow farm entry traits were age, weight, BF and LMA. Sow traits included whether or not a gilt farrowed (STAY), age at first farrowing and total number born (TNB). Fertility groups were; FG0=did not reach puberty at the GDU (NOPUB), did not farrow (DNF); FG1=reached puberty at the GDU (YESPUB), DNF; FG2=NOPUB, farrowed; FG3=YESPUB, farrowed. Genetic lines differed (P<0.05) for estrous traits LOE, TSRBOAR, MSRNOBOAR, TSRNOBOAR, VR, VISUAL VULVA and VW. Females fed restrictively vs. ad libitum had a longer (P<0.05) LOE (2.18 vs. 2.03d), higher (P<0.05) TSRBOAR (15.4 vs. 14.0) and younger (P<0.05) AGEPUB (219 vs. 225d). Fertility groups 0, 1, 2 and 3 contained 45 (4%), 255 (24%), 66 (6%) and 698 (66%) gilts, respectively. Gilts from FG3 in comparison to FG1 had a longer (P<0.05) LOE (2.16 vs. 2.06d), greater (P<0.05) MSRBOAR (7.6 vs. 7.4) and greater (P<0.05) TSRBOAR (15.4 vs. 14.6). Fertility group 0 had less (P<0.05) BF, poorer (P<0.05) LOC and was narrower (P<0.05) ribbed compared with the other FG's. Based on these results it was concluded that gilts with LOE ≤1 day or weak standing reflexes were less likely to farrow a litter.

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

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.