Number Born Alive Research Articles

Effect of polymorphism in the leukemia inhibitory factor gene on litter size in Large White pigs

DNA polymorphism of the porcine leukemia inhibitory factory (LIF) was investigated and used to study the effects on litter size in Large White pigs. A total of 2,167 litter records from 420 sows genotyped at two SNP loci (LIF1 and LIF2) within LIF gene were analyzed to determine whether LIF influenced total number born (TNB) and number born alive (NBA). The results indicated that B allele at LIF1 locus and A allele at LIF2 locus seem to have advantageous effects on litter size. However, the combined analyzed results demonstrated that genotype AAAA, ABBB, and BBBB are better than genotype AAAB, AABB, and ABAB for TNB and NBA in either third to eighth parity or all parities. In all parities, the sows with AAAA genotype had an advantage of 1.76 piglets (P < 0.001) for TNB and 1.44 piglets (P < 0.01) for NBA per litter over the AAAB sows, respectively. The results in this study demonstrated that LIF gene was significantly associated with litter size in pigs.

Growth Hormone–releasing Hormone Plasmid Treatment by Electroporation Decreases Offspring Mortality Over Three Pregnancies

LifeTideSW5 is a growth hormone-releasing hormone (GHRH)-expressing plasmid delivered by intramuscular (IM) electroporation (EP), and the first therapeutic plasmid delivered by this physical method to be approved for use in food animals. Gestating sows (n = 997) were treated once with a single 5-mg GHRH-plasmid by EP or served as controls. Data on offspring from three parities subsequent to treatment were collected. No adverse effects related to treatment were noted. First parity post-treatment offspring from treated sows displayed a 2.93 kg (P < 0.0001) increase in carcass weight (CW), 1.0 mm (P < 0.0001) less back-fat (P2), and a 27.0 g CW/day (P < 0.0001) increase in rate of gain (ROG) compared with controls. An increase of 21.6% was recorded in the number of offspring surviving. In the second and third parities post-treatment, offspring from treated females displayed higher number of born alive and total born number, and lower stillborn rates. Third parity offspring from treated sows displayed a 1.6 kg advantage in CW (P < 0.05), 1.0 mm less P2 (P < 0.05), and a 10.0 g CW/day benefit in ROG. Furthermore, offspring from treated females had a 19.04% lower post-wean loss rate. Overall, plasmid GHRH administration decreased morbidity and mortality in treated females and their offspring over three consecutive pregnancies.

Selection for litter size at day five to improve litter size at weaning and piglet survival rate1

Selection for total number of piglets born (TNB) since 1992 has led to a significant increase in this trait in Danish Landrace and Danish Yorkshire but has also been accompanied by an increase in piglet mortality. The objective of this study was to estimate the genetic and phenotypic parameters for litter size and survival to find alternative selection criteria to improve litter size at weaning. Data from Landrace (9,300 litters) and Yorkshire (6,861 litters) were analyzed using REML based on a linear model including genetic effects of sow and service-sire. The estimates of heritability (based on the sow component) for TNB, number born alive (NBA), and number alive at d 5 after birth (N5D) and at weaning (about 3 wk, N3W) ranged from 0.066 to 0.090 in Landrace and 0.050 to 0.070 in Yorkshire. Genetic correlations between TNB and N3W were 0.289 in Landrace and 0.561 in Yorkshire, but between N5D and N3W the estimated genetic correlation was 0.995 in both populations. The approximate estimates of heritability for survival rate per litter at birth (SVB = NBA/TNB), from birth to d 5 (SV5 = N5D/NBA), and from d 5 to weaning (SVW = N3W/N5D) were 0.130, 0.131, and 0.023, respectively, in Landrace, and 0.095, 0.043, and 0.009, respectively, in Yorkshire. Genetic correlations between TNB and survival rates at different stages were negative. On the other hand, genetic correlations between N5D and survival rates and between N3W and survival rates were strongly or moderately positive, except for the correlations with SVW in Yorkshire. The results suggest that selection for N5D could be an interesting alternative to improve litter size at weaning and piglet survival for Danish Landrace and Danish Yorkshire.

Genetic variation of farrowing kinetics traits and their relationships with litter size and perinatal mortality in French Large White sows

Genetic parameters of litter traits and their relationships with farrowing kinetics traits were estimated in a Large White population to examine the impact of selection for litter size on perinatal mortality and one of its main determinants, farrowing kinetics. Data were collected on 2,947 farrowings from 1,267 sows between 1996 and 2004. Litter traits included the number born in total (NBT), number born alive (NBA), and the number (NSB) and proportion (PSB) of stillborn piglets. Four farrowing kinetics traits were considered: farrowing duration (FD), birth interval (BI = FD/NBT), heterogeneity of birth intervals (SDNB = SD of the number of piglets born each one-half hour), and birth assistance (BA) during the farrowing process. Genetic parameters were estimated using restricted maximum likelihood methodology. All traits were analyzed using a mixed linear animal model including year x month and parity as fixed effects; the additive genetic value of each animal and the sow permanent environment were treated as random effects. To normalize their distribution, kinetics traits were Box-Cox-transformed. Low heritability estimates were obtained for litter size and mortality traits, which was in agreement with literature results (i.e., 0.10 +/- 0.02, 0.08 +/- 0.02, 0.19 +/- 0.02, and 0.14 +/- 0.02 for NBT, NBA, NSB, and PSB, respectively). Heritability values were also low for kinetics traits: 0.10 +/- 0.02, 0.08 +/- 0.02, 0.01 +/- 0.01, and 0.05 +/- 0.03 for FD, BI, SDNB, and BA, respectively. The genetic correlation between NBT and NBA was strongly positive (ra = 0.90). On both phenotypic and genetic scales, NBT was positively associated with stillbirth (ra = 0.45 +/- 0.11, rp = 0.38 for NSB; ra = 0.46 +/- 0.13, rp = 0.17 for PSB). Conversely, NBA had low correlations with SB and PSB. Number born in total was moderately correlated to FD (ra = 0.34 +/- 0.15) and BI (ra = -0.37 +/- 0.15). A stronger relationship was found between NBA and BI (ra = -0.49 +/- 0.13), whereas the relationship with FD was lower (ra = 0.16 +/- 0.17). Moreover, FD was strongly correlated with stillbirth (ra = 0.42 +/- 0.12 with NSB), whereas BI was nearly independent of stillbirth. Contrary to selection on NBT, selection on NBA appears to be a good way to limit the negative side effects on stillbirth. Moreover, selection on NBA would lead to a small increase in FD and a faster and more regular birth process than would be obtained by selecting on NBT.

Optimal Multiple Trait Selection for Multiple Linked Quantitative Trait Loci

Abstract A method was developed to optimize selection on multiple traits with multiple quantitative trait loci (QTLs) over multiple generations. The basis of the method was to replace in the objective function the genotypic value of a single trait with an aggregate genotypic value of multiple traits weighted by their corresponding economic weight, and to maximize the weighted sum of the selection response in the planning horizon. The optimization was formulated as a multiple stage optimal control problem and solved by a forward and backward iteration cycle. The practical utility of this method was illustrated in an example of pig breeding population, in which the number born alive (NBA) and days to 100 kg (D100) were used as parameters. The selection response of this method was compared with standard QTL selection and regular best linear unbiased prediction (BLUP) selection. Results showed that optimal selection achieved greater selection response than either standard QTL or regular BLUP selections. The influence of economic weight to optimal selection was significant, and the optimization was better as the economic weight of D100 increased. Optimal selection increased the total selection response by two ways: 1) it sacrificed some QTL responses during early generations and 2) it put more emphasis on D100. Optimal cumulative discounted selection gave more weight to D100 than optimal terminal selection in the longer generations.

Genetic variation and responses in reproductive performance of sows in lines selected for growth rate under restricted feeding

AbstractThe objective of this study was to examine genetic changes in reproduction traits in sows (total number born (TNB), number born alive (NBA), average piglet birth weight (ABW) and number of piglets weaned (NW), body weight prior to mating (MW), gestation length (GL) and daily food intake during lactation (DFI)) in lines of Large White pigs divergently selected over 4 years for high and low post-weaning growth rate on a restricted ration. Heritabilities and repeatabilities of the reproduction traits were also determined. The analyses were carried out on 913 litter records using average information-restricted maximum likelihood method applied to single trait animal models. Estimates of heritability for most traits were small, except for ABW (0·33) and MW (0·35). Estimates of repeatability were slightly higher than those of heritability for TNB, NBA and NW, but they were almost identical for ABW, MW, GL and DFI. After 4 years of selection, the high growth line sows had significantly heavier body weight prior to mating and produced significantly more piglets born alive with heavier average birth weight than the low line sows. There were, however, no statistical differences between the selected lines in TNB or NW. The lower food intake of high relative to low line sows during lactation was not significant, indicating that daily food intake differences found between grower pigs in the high and low lines (2·71 v. 2·76 kg/day, s.e.d. 0·024) on ad libitum feeding were not fully expressed in lactating sows. It is concluded that selection for growth rate on the restricted ration resulted in beneficial effects on important measures of reproductive performance of thea sows.

豚の一腹総産子数および生存産子数の選抜による産子数の改良効果

豚の一腹総産子数および生存産子数の選抜による産子数の改良効果

Genotype by mating type interaction for litter size in Landrace and Large White sows

AbstractData obtained from a detailed base from a commercial breeding company of Landrace and Large White purebred nucleus sows were used to estimate genetic parameters of piglet number born alive (NBA) following artificial insemination and natural service. Heritabilities were small but significantly different from zero, and similar to literature estimates. The genetic correlation (rG) of NBA after AI or natural service using pooled data was 0·71 and was significantly different from one (P&lt;0·01) but not significantly different between breeds (P&gt;0·1). It is concluded that mating type may result in a re-ranking of sow genetic merit for NBA.

Divergent selection for uterine capacity in rabbits. III. Responses in uterine capacity and its components estimated with a cryopreserved control population1

This work evaluated the response to 10 generations of divergent selection for uterine capacity (UC) in rabbits to determine whether this response was symmetric by contrasting both lines against a cryopreserved control population. Animals came from the 13th generation of an experiment of divergent selection for UC and from a cryopreserved control population. The two UC lines were divergently selected for 10 generations, and selection was relaxed from the 11th generation until the 13th generation. Uterine capacity was estimated as litter size (LS) in unilaterally ovariectomized (ULO) does. To create the control population, embryos from the base generation were vitrified and stored in liquid N2 for 10 generations. Data from 461 pregnancies produced by 134 ULO does were used: 62 does from the high UC line, 55 females from the low UC line, and 17 females from the control line. The following traits were analyzed: ovulation rate (OR); number of implanted embryos (IE); (UC), estimated as total number of rabbits born; number born alive (NBA); prenatal survival (PS), estimated as UC/OR; embryo survival (ES), estimated as IE/OR; and fetal survival (FS), estimated as UC/IE. Ovulation rate, IE, PS, ES, and FS were measured by laparoscopy only in the second parity. Uterine capacity and NBA were measured over four parities. Responses in UC and its components were estimated as differences between the selected lines and the control line using a Bayesian approach. Selection for UC led to differences of 1.01 kits between the high and low lines, but this response was asymmetric. No differences were found between the high and control lines (high - control = -0.08), whereas the low and control lines differed by 1.08 kits, with a probability of the difference being greater than zero of 0.98. Difference between the high and low lines and between the control and low lines was one-half of the difference reported for correlated response in LS in previous studies. No differences in OR were detected among lines. The control and low lines differed by 1.06 IE, with a probability of the difference being higher than zero of 0.84. Prenatal survival for the low line was less than that of the control line. In summary, selection for UC was asymmetric, which was mainly due to a correlated response in PS. Response in UC was one-half of the difference reported for correlated response in LS in previous studies.

Divergent selection for uterine capacity in rabbits. II. Correlated response in litter size and its components estimated with a cryopreserved control population1

Our objective was to evaluate the correlated responses to selection for litter size and its components after 10 generations of divergent selection for uterine capacity (UC). A total of 294 intact females from the 11th and 12th generations of divergent selection for high and low UC and from a cryopreserved control population was used (139, 112, and 43 females, respectively). Uterine capacity was assessed as litter size in unilaterally ovariectomized females. Traits recorded on females for up to five parities were litter size (LS) and number born alive (NBA). Laparoscopy was performed in all females at d 12 of their second parity, and the ovulation rate (OR) and number of implanted embryos (IE) were recorded in these females. Embryo survival (ES = IE/OR), fetal survival (FS = LS/IE), and prenatal survival (PS = LS/OR) were computed. Correlated responses in LS and in its components were inferred using Bayesian methods. Correlated responses in LS were asymmetric. The divergence between high and low lines was 2.35 kits, mainly because of a higher correlated response in the low line (1.88 kits). The lower LS in the low line was associated with a lower PS (control - low = 0.14), because of decreases in ES and FS.

Oestrogen receptor genotypes and litter size in Hungarian Large White pigs

A total of 869 litter records of 226 Hungarian Large White sows have been analysed to investigate the possible use of the oestrogen receptor gene (ESR) as marker to improve litter size. First, second and later parities have been evaluated separately. Frequencies of A = 0.55 and B = 0.45 have been calculated for the two ESR alleles and the observed/ expected number of the three genotypes were as follows: AA: 71/69.1, AB: 108/111.8 and BB: 47/45.1. BB type first and later parity sows were superior to AB and AA sows for number born alive (NBA), total number of born (TNB) and the corrected number of weaned piglets (CNW), respectively.

An investigation into the genetic relationship of reproduction traits of sows under different mating method (artificial insemination versus natural service)

Falconer and MacKay (1996) note that the measurement of a trait in two different environments may be considered as two traits rather than one. In this way it is possible, through the calculation of genetic correlations, to estimate to what extent the two measurements under different conditions are in fact the same characteristic and are determined by the same genes. The widespread use of AI in pig production has faltered due to problems with dilution and cryopreservation of semen and yet an industry split, where breeders and nucleus herds use AI extensively but multipliers and commercial producers do not, is becoming apparent. Reproductive traits are increasingly seen as an important component of overall pig production and while the genetic correlation between reproductive and production traits has been explored, little work has focused on the genotype by environment interaction of such fertility traits. The present study reports the genetic relationship of number born alive (NBA) in litters conceived naturally and by AI, and in rate of weaning to first service (WTFS-1).

FSHR Gene Mutation and Its Effect on Litter Size in Pigs

The polymorphism of the locus FSHRB in intron6-Exon7 of FSHR gene was investigated by PCR-RFLPs in Erhualian, Large White and Landrace×Large White; The association of polymorphism and litter size was analyzed by using SAS. The results showed that 1) the polymorphism of the locus FSHRB was significantly associated with litter size; 2) the total born number (TBN) and number born alive (NBA) of the sows with BB genotype were increased (p<0.05) with additive effects of 1.02-1.42 and 1.04- 1.27 pigs per litter, respectively; 3) among the sows with genotype AA, AB or BB, there was an insignificant difference in born weight and weaning weight. This gene may be an effective potential tool used in conjunction with traditional selection methods. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 2 : 179-182)

Candidate gene markers for reproductive traits in polish 990 pig line

SummaryThe follicle‐stimulating hormone (FSHB), the prolactin (PRL) and prolactin receptor (PRLR) genes were examined as candidate genes for swine reproductive traits. The experimental material included 444 sows of the Polish synthetic line 990. The following traits were included in the study: total number born (TNB), number born alive (NBA) number of piglets at 21 days of age (NP21), number of weaned piglets, litter weight at 21 days of age, litter weight at weaning. The PRL locus genotype was found to have a significant effect (p ≤ 0.01) on the TNB, NBA and NP21 based on analysis of sows records from second and later parities. The effect of PRLR genotype was significant (p &lt; 0.05) for the NBA for sows during first parity. No significant effects of the FSHB sow genotype were found in part because of a low frequency of one of the homozygous genotypes at this locus observed in the tested material.

Estrogen receptor polymorphism in Landrace pigs and its association with litter size performance

Polymorphism at the estrogen receptor locus (ESR) and its association with reproductive performance in Landrace pig is reported. A total of 124 sows from a control line, and 163 sows from a line selected for litter size were genotyped. The traits studied were number born alive (NBA) and total number born (TNB). Prolificacy in first, second and third or later parities were considered as three different traits. A mixed model considering the ESR genotype as a fixed effect and polygenic background as a random effect, was carried out using Bayesian inference, implemented via the Gibbs sampling procedure. Two alternative statistical models, with and without ESR genotype by line interaction, were considered. Association of an additive ESR effect with NBA and TNB was not detected. Moreover, in third and further parities, a line by ESR genotype interaction was observed for both NBA and TNB. For third and further parities, allele B was associated with increasing litter size in selected animals, whereas the opposite was observed in control animals. These results suggest that a background genotype by ESR interaction exists, although a spurious association due to sampling or the possibility of different linkage phases between the ESR polymorphism and a putative QTL close by cannot be ruled out.

Genetic parameters and trends for litter traits in U.S. Yorkshire, Duroc, Hampshire, and Landrace pigs.

Records on 251,296 Yorkshire, 75,262 Duroc, 83,338 Hampshire, and 53,234 Landrace litters born between 1984 and April of 1999 in herds on the National Swine Registry Swine Testing and Genetic Evaluation System were analyzed. Animal model and restricted maximum likelihood procedures were used to estimate variances of animal genetic (a), maternal genetic (m), permanent environmental, and service sire, and the covariances between a and m for number born alive (NBA), litter weight at 21 d (L21WT), and number weaned (NW). Fixed effects of contemporary groups were included in the analysis. Based on a single-trait model, estimates of heritabilities were 0.10, 0.09, 0.08, and 0.08 for NBA; 0.08, 0.07, 0.08, and 0.09 for L21WT; and 0.05, 0.07, 0.05, and 0.05 for NW in the Yorkshire, Duroc, Hampshire, and Landrace breeds, respectively. Estimates of maternal genetic effects were low and ranged from 0.00 to 0.02 for all traits and all breeds. Estimates of permanent environmental effects ranged from 0.03 to 0.08. Estimates of service sire effects ranged from 0.02 to 0.05. A bivariate analysis was used to estimate the genetic correlations among traits. Average genetic correlations over the four breeds were 0.13, 0.15, and 0.71 for NBA with L21WT, NBA with NW, and L21WT with NW, respectively. Average genetic trends were 0.018 pigs/yr, 0.114 kg/yr, and 0.004 pigs/yr for NBA, L21WT, and NW, respectively. Although estimates of heritabilities for litter traits were low and similar across breeds, genetic variances for litter traits were sufficiently large to indicate that litter traits could be improved through selection. This study presents the first set of breed-specific estimates of genetic parameters available from large numbers of field records. It provides information for use in national genetic evaluations.

Selection for maternal behavior in mice—direct and correlated responses

Three generations of divergent selection for a maternal care index (MCI) in mice were practiced in each of three replicates. MCI was recorded for 29–32 dams and litters in each replicate/line subclass. Pups of the top (or bottom) 6–10 dams in each replicate, depending on number of females in the litters, were selected in high (H) and low (L) MCI lines. At birth, litters with more than 10 pups were standardized to 10 pups whereas litters with no more than 10 pups remained intact. On day 4, 8, 12, and 16 of lactation, time budgets during a 30-min session were recorded by real-time video camera. The times spent in the activities of nursing pups, licking pups, retrieving pups, resting with pups, and building a nest were summed, and MCI was the percentage of the total time devoted to these activities. Number born alive (NBA), number weaned (NW), litter weaning weight (LWW), and mating weight (MW) were recorded. The difference between H and L in cumulative selection differential (CSD) of MCI was 59.8%. Regressions of differences in H and L on generation and on cumulative selection differential were 4.878±0.414 and 0.239±0.011 (realized heritability), respectively ( P<0.01). Means for MCI in Generation 3 for H and L, respectively, were 80.7 and 63.7% ( P<0.01). Variances and covariances among traits were estimated with multiple-trait, derivative-free, restricted maximum likelihood procedures. Estimates of heritabilities of MCI, NBA, NW, LWW, and MW were 0.20, 0.31, 0.12, 0.39, and 0.49, respectively. Genetic correlations of MCI with most traits were low; however, a correlation of 0.78 with number weaned was found indicating selection for MCI may increase pre-weaning survival rate. Selection for MCI was effective because it was heritable (0.24) and highly variable (CV=24.8%), but changes in MCI were not strongly associated with litter size at birth, litter weaning weight, or dam mating weight.

Frequencies, Inheritance of Porcine FSH-β Retroposon and its Association with Reproductive Traits

The fragment in intron I of FSH-β gene was amplified by PCR. According to the polymorphism, we analyzed the distribution of FSH-β retroposon in different pig breeds; its inheritance pattern in Large White×Meishan reference family; and the association of FSH-β retroposon with litter size, female reproductive organs measurement, ultrasonic backfat and other traits. The results showed that almost each Chinese indigenous pig had the retroposon, while foreign pig breeds rarely had; the frequencies of porcine FSH-β retroposon were strongly associated with breeds (p<0.01); the pattern of inheritance was consistent with Mendelian fashion; total number born (TNB) and number born alive (NBA) were increased per FSH-β retroposon (p<0.01) with additive effects of 1.2-1.8 and 1.4-1.8 pigs/litter, respectively; between the FSH-β retroposon carriers and non-carriers, there was an insignificant difference in the measurement of female reproductive organs, body weight at birth, backfat thickness, loin meat height, lean meat percentage, teat number, days to 100 kg, and average daily gain. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 2 : 179-183)

The combined genotypes effect of ESR and FSHβ genes on litter size traits in five different pig breeds

Estrogen receptor (ESR) and Follicular-stimulating hormone beta subunit (FSHβ) genes were chosen as candidates to determine whether they control litter size and some other reproductive traits in swine. 269 sows from five different pig breeds were genotyped by an established PCR-RFLPs protocol at both ESR and FSHβ loci. The effects of both ESR and FSHβ on pig reproductive traits, including total number born (TNB) and number born alive (NBA), are analyzed by SAS software (version 6.12). These computation results demonstrated that both ESR locus and FSHβ locus are the major genes influencing litter size in pigs. The sows of BBBB combined genotype of ESR and FSHβ loci generally produce 1.85–3.01 TNB and 2.0–3.0 NBA more than those of ABAA combined genotype. The notable effect of ESR locus and FSHβ locus on litter size of pigs have made it possible to inprove the pig reproduction by Marker-assisted selection (MAS). Moreover, introgression of the beneficial alleles into commercial pig breeding lines, in which the alleles were not present, will improve greatly the economically important reproductive traits and efficiency of pig production.

Genetic parameters for lean meat yield, meat quality, reproduction and feed efficiency traits for Australian pigs: 3. Genetic parameters for reproduction traits and genetic correlations with production, carcase and meat quality traits

Genetic parameters were obtained using REML procedures applied to a multiple trait animal model for number born alive (NBA), litter birth weight (LBW), average piglet weight at birth (ABW) recorded in the first, second and third parity (NBA 1,2,3, LBW 1,2,3, ABW 1,2,3) and 21-day litter weight (LW21 1) for 6050 Large White and Landrace sows. Heritability estimates ranged from 0.06 to 0.22 for these reproductive traits, with lowest estimates for NBA 1,2,3 and LW21 1. Reproductive performance in the first parity should be regarded as a different trait than reproductive performance in later parities (range of genetic correlations (rg): 0.52–0.78, ±0.16–0.30). NBA 1,2,3 was unfavourably related with LBW 1, ABW 1,2,3 and LW21 1. In addition, NBA 1,2,3 was negatively correlated with growth rate traits, feed intake and weight of the back leg and ham (BLW, LMW) (rg range: −0.45 to −0.01, ±0.13–0.15). In contrast, genetic correlations were favourable between LBW 1,2,3, ABW 1,2,3 and growth rate, BLW and LMW (rg values: 0.08–0.55, ±0.12–0.25). NBA 1,2,3 and ABW 1,2,3 were not genetically related with backfat measurements, while a low backfat was associated with a high LBW 1,2,3 (rg: −0.54 to −0.08, ±0.09–0.36). Genetic correlations between reproduction traits and meat quality traits were inconsistent between traits and parities. A lower intramuscular fat content was associated with a higher LBW 1,2,3 and ABW 1,2,3 (rg: −0.37 to −0.12, ±0.12–0.18). In summary, genetic correlations between reproduction traits and performance traits were only unfavourable between litter size and growth rate and feed intake. Genetic correlations between litter birth weight and average piglet weight at birth indicate that selection for leanness will also improve litter weight traits.