A review of factors influencing litter size in Irish sows

The impact of herd age structure on the performance of commercial sow-breeding farms

BACKGROUND

The herd age structure, i.e., distribution of sows within a farm based on their parity number, and its management are essential to optimizing farm reproductive efficiency. The objective of this study is to define different types of herd age structure using data from 623 Spanish commercial sow farms. Additionally, this study aims to determine which type of herd age structure can enhance reproductive efficiency at the farm level.

RESULTS

Farms are classified into three groups according to the quadratic function fitted to the percentage of sows by parities. This classification unveils three types of herd structures: type 1 (HS1) exhibits a concave-downward trend, with a higher percentage of sows in intermediate parities (mean of 45.5% sows between the 3rd to 5th parity); type 2 (HS2) presents a trend curve that is close to a straight line, with a gradual decrease in the percentage of sows per parity (approximately 2% loss of sows census per parity); and type 3 (HS3) shows an upward concave trend curve, with an increase in the percentage of sows in later parities (19.0% of sows between 7th and ≥ 8th parity). Parametric tests assess productivity differences between the three types of herd structures (p < 0.01). HS1 farms have the best productive outcomes over a year, with 31.2 piglets weaned per sow and year (PWSY) and a farrowing rate of 87%, surpassing HS2 and HS3 farms (30.1 and 28.7 PWSY; 85.3% and 83.4% farrowing rates, respectively). HS1 also have the lowest percentage of sows returning to oestrus (11.8%) and the highest number of weaned piglets per litter (12.8), compared to HS2 (13.2% and 12.4 piglets weaned) and HS3 (15.1%, 11.9 piglets weaned). These differences show a medium effect size (η2 between 0.06 to < 0.14).

CONCLUSIONS

This study shows the importance of herd age structure on sow-breeding farms as a factor of reproductive efficiency. The results endorse the proposed classification based on the curvature of the trend parabola obtained with the quadratic function to categorize herd structures into three groups. Additionally, these findings highlight the importance of considering the herd age structure in farm decision-making.

Comparative developmental competence of in vitro embryos recovered from Bali cattle with normal and poor sperm motility

Background and Aim

Fertility is crucial for enhancing the efficiency of livestock production, as it directly impacts the reproductive rates. A comprehensive understanding of the relationship between sperm quality and embryo development is key to optimizing reproductive outcomes and improving the quality of livestock. This study analyzed the developmental competence of in vitro embryos recovered from Bali cattle with normal or poor sperm motility.

Materials and Methods

Nine bulls with normal fresh semen (NFS) or poor fresh semen (PFS) motility were ejaculated for semen. Semen ejaculates, including volume, motility, and sperm concentration, were evaluated immediately after collection to measure the quality of the fresh semen. Frozen semen was evaluated using computer-assisted semen analysis (CASA) for motility, progressive sperm motility, distance curve path, distance curve linear, distance straight line, average path velocity, curvilinear velocity, linear velocity, straightness (STR), linearity of forward progression (LIN), wobble, and average lateral head displacement (ALH). Bull groups were used to determine in vitro embryo cleavage ability after fertilization of Bali cattle. Ovaries of Bali cattle were collected by slicing, and only cytoplasmic oocytes with compact cumulus cells were used in this study. The oocytes were matured, and in vitro fertilization was performed using fertilization media with a final sperm concentration of 1.5 × 106 spermatozoa/mL. After 48 h, the embryo cleavage ability of the cultured oocytes was evaluated.

Results

There were significant differences in motility values between the NFS and PFS groups; however, there were no significant differences in the volume or sperm concentration. There was a significant difference in the LIN value between the groups but no significant differences in other CASA parameters. There were no significant differences in the cleavage rate and morula between the groups, but a positive correlation was observed between the cleavage rate and the morula and between the morula and ALH. A significant negative correlation was observed between the cleavage rate and STR and between the morula and STR; no significant differences were observed for other variables.

Conclusion

Despite variations in sperm characteristics, both normal and poor sperm motility demonstrated comparable in vitro embryonic development competence. These findings provide important insights into the fertility potential of Bali bulls, providing valuable information that can enhance selection strategies to improve the quality of livestock production.

Preweaning piglet survival on commercial farms

Preweaning piglet mortality (PWM), a trait highly related to litter size, is one of the main concerns associated with productive efficiency and animal welfare in commercial pig farms. The objectives of this work were to study piglet survival at the farm level, to establish a survival rate (SR) as a target indicator to be improved, and to model it based on other reproductive parameters. Analyzed data corresponded to 580 Spanish commercial farms with a total inventory of 809,768 sows. These farms showed a mean SR of 85.70% piglets born alive (BA), which decreased to 81.81% when total piglets born (TB) were considered. The SR was strongly associated with prolificacy (P < 0.01), the parities with the highest prolificacy being those that had the lowest SR. Thus, the highest correlations were for the SR of piglets BA in the third and fourth parities (r = -0.460 and r = -0.452, respectively, P < 0.01), and for the SR of piglets TB in the fourth parity (r = -0.546, P < 0.01), which was the one with the highest prolificacy. The values corresponding to the quartile of farms with the highest SR within the most productive farms were established as targets to be improved, which were ≥88.5% of piglets BA and 83.2% of piglets TB. Nevertheless, the direct associations shown between the piglet's survival and prolificacy and other productive factors, such as the age of piglets at weaning, the farrowings per sow and year and the farrowing interval, suggest the convenience of modeling the risk of PWM on farms to have its own target of survival index to be improved.

Genetic parameters for linear conformation, stayability, performance and reproduction traits in German local Swabian-Hall landrace sows

Improvements of longevity in sows are of overriding importance from an animal welfare as well as from an economic perspective, also in the local Swabian-Hall Landrace (SHL) breed. Consequently, the aim of the present study was a detailed assessment of linear conformation traits in the context of early predictions of sow stayability and to infer genetic (co)variance components between conformation traits with reproduction and performance traits. In this regard, we implemented a linear 9-point scoring system for conformation traits reflecting the body morphology and feet and leg characteristics in gilts. Linear conformation trait scoring included body length (BLEN), body height (BHEI), hind leg angularity (HLANG), hind leg pastern (HLPAS), hind cannon bone strength (HCBS), hind leg position (HLPOS), front leg position (FLPOS), claw length (CLEN) and muscling (MUSC) from 6042 SHL gilts before first insemination at the age of 180-200 days. For the same gilts, performance traits included average daily gain (ADG) and back fat thickness (BF) measured via ultrasound, reproduction traits included the number of piglets born alive (NBA) and the number of piglets weaned (NWEAN), and stayability was a binary trait reflecting sow survival after parity 2 (STAY_12), 3 (STAY_13) and 4 (STAY_14). For the estimation of variance components and heritabilities, single-trait linear animal models were defined for conformation, performance and reproduction traits, and single-trait generalized linear mixed models with a logit link function for binary stayability traits. Genetic covariances and correlations were inferred in series of bivariate runs for all combinations of conformation and remaining traits. The distribution of the assigned conformation scores reflected a Gaussian distribution, but a large fraction of records was assigned to the intermediate score classes 4, 5 and 6. Accordingly, the restricted utilization of the 9-point scale might explain the small genetic variances and small heritabilities for feet and leg traits in the range from 0.06 to 0.17. Heritabilities were larger for the linear traits reflecting body morphology, i.e., for BLEN (0.21) and BHEI (0.20). For conformation traits, the common litter environment explained up to 17% of the phenotypic trait variation. Genetic and especially phenotypic correlations between linear conformation traits with the reproduction traits NBA and NWEAN were close to zero. Heritabilities for STAY_12, STAY_13 and STAY_14 were 0.08, 0.07 and 0.05, respectively. Moderate genetic relationships were estimated between STAY_14 with some conformation traits. Especially high scores for BHEI and BLEN (i.e., long and large gilts) implied a decline in STAY_14 genetically (r_g  = -0.24 and -0.53, respectively). Moderate genetic correlations were estimated between HLANG with STAY_14 (0.28), and between HCBS with STAY_12 (0.23). For most of the conformation traits with intermediate optimum, genetic correlations with STAY were close to zero, indicating improved longevity for gilts representing the population average with scores 4, 5 or 6, and suggesting the development of appropriate selection indices in this regard.

Second litter syndrome in Iberian pig breed: factors influencing the performance

Second litter syndrome (SLS) consists of a loss of prolificacy in the second parity (P2), when a sow presents the same or lower results for litter size than in the first parity (P1). This syndrome has been reported for modern prolific breeds but has not been studied for rustic breeds. The objectives of this study are to determine how and to what degree Iberian sows (a low productivity breed recently raised on intensive farms) are affected by SLS; to establish a target and reference levels; and to assess the factors influencing the performance. Analysed data correspond to 66 Spanish farms with a total of 126 140 Iberian sows. The average Iberian sow prolificacy in P1 was 8.91 total born (TB) and 8.47 born alive (BA) piglets, whereas in P2, it decreased by -0.05 TB and -0.01 BA piglets, suggesting some general incidence of SLS. At the sow level, 56.63% did not improve prolificacy in terms of BA piglets in P2, and 16.98% had a clear decrease in prolificacy, losing ≥3 BA piglets in P2. Within herds, a mean of 57.75% of sows showed SLS, with an evident decrease in the number of BA piglets in P2. The plausible target for the Iberian farm's prolificacy comes from the quartile of farms with the lowest percentage of SLS sows within the farms with the highest prolificacy between P1 and P2 (mean of 8.77 BA). So, in this subset of farms (N = 17), 47.3% of sows improved their prolificacy in P2 (i.e. did not show SLS). Hence, half the sows could be expected to show SLS even on farms with a good performance. Finally, this study brings out the main factors reducing P2 prolificacy through SLS in the Iberian breed: later age at first farrowing, long first lactation length, medium weaning to conception interval and large litter size in P1. In conclusion, improving the reproductive performance of Iberian farms requires reducing the percentage of sows with SLS, paying special attention to those risk factors. The knowledge derived from this study can provide references for comparing and establishing objectives of performance on Iberian sow farms which can be used for other robust breeds.

Predicting fertility from sperm motility landscapes

Understanding the organisational principles of sperm motility has both evolutionary and applied impact. The emergence of computer aided systems in this field came with the promise of automated quantification and classification, potentially improving our understanding of the determinants of reproductive success. Yet, nowadays the relationship between sperm variability and fertility remains unclear. Here, we characterize pig sperm motility using t-SNE, an embedding method adequate to study behavioural variability. T-SNE reveals a hierarchical organization of sperm motility across ejaculates and individuals, enabling accurate fertility predictions by means of Bayesian logistic regression. Our results show that sperm motility features, like high-speed and straight-lined motion, correlate positively with fertility and are more relevant than other sources of variability. We propose the combined use of embedding methods with Bayesian inference frameworks in order to achieve a better understanding of the relationship between fertility and sperm motility in animals, including humans.

Dimension reduction methods on porcine sperm motility landscapes reveal heterogeneity and hierarchy in sperm movement behavior and show high-speed and straight-lined motion as predictive features of fertility.

Traits Defining Sow Lifetime Maternal Performance

Declining sow performance with increasing parity or an increase in the number of poor- quality pigs potentially impacts on farm productivity. This study investigated the phenotypic and genetic background of the sow's influence on (i) the number of pigs not meeting the industry standards (tail-enders) and (ii) changes in performance with parity. Data were available for 3592 sows and their litters (13,976 litters) from a pig production system in NSW, Australia. The mean, standard deviation (SD), and slope for trait values over time were estimated for the sow characteristic traits: number of born-alive (NBA) and stillborn (SB) piglets and body condition of sow recorded with a caliper (CAL), along with maternal effects on piglet performance, represented by: average piglet birth weight (APBW), number of weaned piglets (WEAN), and tail-enders (TEND). Traits were analyzed in ASReml 4.2, by using an animal model. The number of tail-enders produced by a sow is a heritable trait, with a heritability estimate of 0.14 ± 0.04. Sow characteristics and maternal effects on piglet performance expressed by mean and slope had similar heritability estimates, ranging from 0.10 ± 0.03 to 0.38 ± 0.05, whereas estimates for SD traits were generally not different from zero. The latter suggests individual variability in sow characteristics or maternal performance between parities is largely not genetic in origin. This study demonstrated that more attention is required to identify contributions to the problem of tail-enders, and that slope traits could potentially be useful in the breeding program to maximize lifetime performance.

Productive and biological features of breeding Irish pigs of various genotypes in Western Siberia

The present work studies the productive and biological characteristics of breeding Irish pigs of different genotypes in the conditions of Western Siberia. Pure-bred selection of Large White pigs (WP) was used in the first control group and intra-breed selection of Landrace pigs (LP) was used in the second control group. The following patterns of interbreeding were used in the experimental groups: ♀WP × ♂LP (third group), ♀LP × ♂WP (fourth group). In terms of reproductive qualities, the best combination should be considered the selection of ♀WP × ♂LP, in which 8.1% (p <0.05) more piglets were obtained at 30 days, with a 10.0% (p <0.05) higher weight of the nest at 30 days and 3.6% (p <0.05) greater safety than in the first control group. The combination of breeds according to the ♀LP × ♂WP scheme contributed to an increase in the average daily 13.7% (p <0.05) gain in live weight of the resulting offspring. At the age of 4 months, piglets of the LP × WP genotype had a 10.9% (p <0.05) higher content of total protein in the blood serum than in animals of the Large White breed. The muscle tissue of Large White pigs was characterized by a 5.2% (p <0.05) higher moisture binding capacity in relation to Landrace pigs. The melting point of fatty tissue was lower in Large White pigs by 14.3% (p <0.05). The fatty tissue of LP × WP hybrids has a 10.0% higher melting point (p <0.05) in contrast to Large White pigs.

Establishment of a multilevel linear model to analyse the factors affecting piglet litter performance at birth

This study aimed to establish a feasible model for analysing factors affecting piglet litter performance at birth. Data of 61,984 litters were collected from 16 herds, and general linear model (GLM), multilevel Poisson regression model (MPM) and multilevel linear model (MLM) were established to compare their goodness of fit for these data. Influencing factors of piglet litter performance at birth were analysed using the established optimal model. Results showed the intraclass correlation coefficients of total born piglets (TBP), piglets born alive (PBA), low-birth-weight piglets (LBW), and average birth weight of piglets (ABW) reached 27.89%, 23.88%, 24.66% and 22.27%, respectively (p < .05). Akaike's information criterion and Bayesian information criterion in MLM of TBP, PBA, LBW and ABW were lower than those in GLM. Pearson residuals in MPM increased to nearly 1 after introduction of a discrete scale factor, and the p values in MPM were similar to those in MLM. Analyses of MLM indicated crossbred sows with good management supplemented with oregano essential oil and farrowing at warm season had higher TBA, PBA and ABW, but lower LBW than other sows (p < .05). In conclusion, MLM is superior to GLM and can replace MPM in analysing discrete data with hierarchical structure in pig production. More importantly, other potential influencing factors of litter performance at birth can be analysed using the established MLM in the future.

Duration of immunity against heterologous porcine parvovirus 1 challenge in gilts immunized with a novel subunit vaccine based on the viral protein 2

BACKGROUND

Porcine parvovirus 1 (PPV1) is widespread in commercial pig farms worldwide and has a significant impact to the swine industry. Long-lasting immunity achieved by means of vaccination is the main tool to prevent PPV1 infection and its associated clinical signs. Here we evaluated the duration of immunity (DOI) conferred by a novel subunit vaccine based on the viral protein (VP) 2 of PPV1, named ReproCyc® ParvoFLEX. The DOI was assessed at 6 months post-vaccination following the standard vaccination scheme (phase I) or after re-vaccination (phase II) with a single injection administered 24 weeks after the basic vaccination scheme. A total of 46, five to six-month-old gilts, free of PPV1 and porcine reproductive and respiratory syndrome virus (PRRSV), were randomly assigned to 6 groups (three in each phase): the negative control groups were inoculated with sodium chloride (NaCl), the vaccinated groups were immunized with the PPV1 subunit vaccine and the strict controls were neither treated nor challenged. Subsequently, the negative control and vaccinated groups from each phase were challenged with a heterologous PPV1 strain. Infection of fetuses was the primary outcome parameter for efficacy, though other supportive parameters were PPV1 viremia and serological status of the gilts and the condition of their fetuses (i.e. normal, autolytic, or mummified).

RESULTS

All gilts vaccinated against PPV1 tested seropositive at challenge and viremia after challenge was detectable only in the non-vaccinated animals. In this regard, fetuses positive to PPV1 by PCR were only found in litters from non-vaccinated sows.

CONCLUSIONS

These results point out that the immunity developed by the PPV1 subunit vaccine is effective in terms of preventing viremia, transplacental infection of fetuses and fetal death caused by PPV1 infection. ReproCyc® ParvoFLEX was demonstrated to protect fetuses against heterologous PPV1 challenge with a DOI of 6 months after vaccination.

Genetic Association between Swine Leukocyte Antigen Class II Haplotypes and Reproduction Traits in Microminipigs

The effects of swine leukocyte antigen (SLA) molecules on numerous production and reproduction performance traits have been mainly reported as associations with specific SLA haplotypes that were assigned using serological typing methods. In this study, we intended to clarify the association between SLA class II genes and reproductive traits in a highly inbred population of 187 Microminipigs (MMP), that have eight different types of SLA class II haplotypes. In doing so, we compared the reproductive performances, such as fertility index, gestation period, litter size, and number of stillbirth among SLA class II low resolution haplotypes (Lrs) that were assigned by a polymerase chain reaction-sequence specific primers (PCR-SSP) typing method. Only low resolution haplotypes were used in this study because the eight SLA class II high-resolution haplotypes had been assigned to the 14 parents or the progenitors of the highly inbred MMP herd in a previous publication. The fertility index of dams with Lr-0.13 was significantly lower than that of dams with Lr-0.16, Lr-0.17, Lr-0.18, or Lr-0.37. Dams with Lr-0.23 had significantly smaller litter size at birth than those with Lr-0.17, Lr-0.18, or Lr-0.37. Furthermore, litter size at weaning of dams with Lr-0.23 was also significantly smaller than those dams with Lr-0.16, Lr-0.17, Lr-0.18, or Lr-0.37. The small litter size of dams with Lr-0.23 correlated with the smaller body sizes of these MMPs. These results suggest that SLA class II haplotypes are useful differential genetic markers for further haplotypic and epistatic studies of reproductive traits, selective breeding programs, and improvements in the production and reproduction performances of MMPs.

Reducing BW loss during lactation in sows: a meta-analysis on the use of a nonstarch polysaccharide-hydrolyzing enzyme supplement

A meta-analysis was performed on eight trials, which included a total of 992 parity 1 to 8 lactating sows, to evaluate the effects of feeding xylanase which is the main enzyme activity present in the enzymatic complex (Rovabio Excel, Adisseo, France) supplement throughout lactation on the following sow performance factors: BW loss, feed intake, backfat depth, and piglet growth. Even a short period of enzyme supplementation during lactation led to a reduction in BW loss of approximately 3 kg per sow (P = 0.003). This reduction represented 1-2% of the BW of sows. This effect could be explained by an increase in feed energy intake and enhanced feed digestibility. Sows fed enzyme-supplemented diets exhibited greater DM, OM, and GE digestibilities (3.4, 3.9, and 4.2% increases, respectively; P < 0.001) than sows fed control diets. During lactation, sows lost from 19 to 25 kg of BW (i.e., approximately 10% of their BW), with a difference between parity groups (P < 0.001). Body reserve mobilization was decreased in sows fed enzyme-supplemented diets (-2.9 kg, P = 0.003), with a more pronounced effect in primiparous than multiparous sows when BW loss is expressed relative to total BW (-2.27 vs. -0.59%, respectively; P = 0.058). Enzyme supplementation also increased litter weight gain up to weaning, with a greater effect in litters from multiparous sows than those from primiparous sows (5.4 vs. 0.6 kg, respectively; P = 0.009). These results could be explained in part by the relationship between their NE intake and either variations in BW or litter weight gain (R2 = 0.51 and 0.49, respectively; P < 0.001). Finally, the meta-analysis suggests that there are differences in the partitioning of the NE intake between growth and milk production and in relation to the sow's parity or physiological status. Extra energy released by enzyme is used for one of these functions (i.e., body mobilization reduction or greater milk export for litter gain).

An association analysis of sow parity, live-weight and back-fat depth as indicators of sow productivity

Understanding how critical sow live-weight and back-fat depth during gestation are in ensuring optimum sow productivity is important. The objective of this study was to quantify the association between sow parity, live-weight and back-fat depth during gestation with subsequent sow reproductive performance. Records of 1058 sows and 13 827 piglets from 10 trials on two research farms between the years 2005 and 2015 were analysed. Sows ranged from parity 1 to 6 with the number of sows per parity distributed as follows: 232, 277, 180, 131, 132 and 106, respectively. Variables that were analysed included total born (TB), born alive (BA), piglet birth weight (BtWT), pre-weaning mortality (PWM), piglet wean weight (WnWT), number of piglets weaned (Wn), wean to service interval (WSI), piglets born alive in subsequent farrowing and sow lactation feed intake. Calculated variables included the within-litter CV in birth weight (LtV), pre-weaning growth rate per litter (PWG), total litter gain (TLG), lactation efficiency and litter size reared after cross-fostering. Data were analysed using linear mixed models accounting for covariance among records. Third and fourth parity sows had more (P0.05). Heavier sow live-weight throughout gestation was associated with an increase in PWM (P0.05). In conclusion, this study showed that sow parity, live-weight and back-fat depth can be used as indicators of reproductive performance. In addition, this study also provides validation for future development of a benchmarking tool to monitor and improve the productivity of modern sow herd.

Cell-specific expression and signal transduction of C-C motif chemokine ligand 2 and atypical chemokine receptors in the porcine endometrium during early pregnancy

Chemokines and atypical chemokine receptors (ACKRs; also known as chemokine decoy receptors) play an important role in reproductive immunology by recruiting leukocytes during early pregnancy. The aim of this study was to determine the expression of C-C motif chemokine ligand 2 (CCL2) and ACKRs in the endometrium during estrous cycle and early pregnancy, and to investigate the functional effects of CCL2 on porcine uterine luminal epithelial (pLE) cells. Our results indicated that CCL2, ACKR1, ACKR3, and ACKR4 were strongly detected in the glandular and luminal epithelium of the endometrium during early pregnancy compared to that in non-pregnant pigs. Recombinant CCL2 improved pLE cell proliferation via activation of the PI3K and MAPK pathways and suppression of endoplasmic reticulum (ER) stress by reducing the expression of ER stress regulatory genes. Collectively, these results provide novel insights into CCL2-mediated signaling mechanisms in the porcine endometrium at the maternal-fetal interface during early pregnancy.

Effect of dietary chitosan oligosaccharide supplementation on the pig ovary transcriptome

Fecundity improvement is one of the most important economic traits for the swine industry. In this study, we identified 486 differentially expressed genes associated with sow prolificacy from COS administrated sow ovaries by RNA-seq.

Stimulatory effects of fibroblast growth factor 2 on proliferation and migration of uterine luminal epithelial cells during early pregnancy

Fibroblast growth factor 2 (FGF2) is a mitogen that induces proliferation, differentiation, and migration of cells, as well as angiogenesis and carcinogenesis via autocrine or paracrine actions. Fibroblast growth factor 2 expression is abundant in porcine conceptuses and endometrium during the estrous cycle and peri-implantation period of pregnancy. However, its intracellular actions in uterine epithelial cells have not been reported. The results of this study indicated abundant expression of FGFR1 and FGFR2 predominantly in uterine luminal and glandular epithelia during early pregnancy and that their expression decreased with increasing parity of the sows. Treatment of porcine uterine luminal epithelial (pLE) cells with FGF2 increased proliferation and DNA replication based on increases in proliferating cell nuclear antigen (PCNA) and initiation of G1/S phase progression. In addition, FGF2 increases phosphorylation of AKT, P70S6K, S6, ERK1/2, JNK, P38, and P90RSK in a time-dependent manner, and increases in their expression was suppressed by Wortmannin (a phosphatidylinositol 3-kinase [PI3K] inhibitor), U0126 (an ERK1/2 inhibitor), SP600125 (a JNK inhibitor), and SB203580 (a P38 inhibitor) based on western blot analyses. Also, the abundance of cytoplasmic p-AKT protein was decreased by Wortmannin and U0126, and p-ERK1/2 protein was reduced only by U0126. Furthermore, inhibition of each signal transduction protein reduced the ability of FGF2 to stimulate proliferation and migration of pLE cells. Collectively, these results indicate that activation of FGFR1 and FGFR2 by uterine- and endometrial-derived FGF2 stimulates PI3K/AKT and mitogen-activated protein kinase pathways for development of the porcine uterus and improvement of litter size.

Effects of different levels of feed intake during four short periods of gestation and housing systems on sows and litter performance

The current study investigated the effects of different levels of feed intake during 4 short periods of gestation and of housing systems on sow and litter performance. A total of 255 multiparous sows were allotted to 1-4 dietary treatments using a randomized complete block design blocking by initial body weight (BW), backfat (BF) and parity. Sows were housed either in individual stalls (n=129) or group pens (n=126) with 55 sows in each pen with electronic sow feeder during gestation. All sows were fed one common corn-soybean meal-based diet with the amount of 1.0×maintenance energy level of feed intake (106×BW^0.75) throughout gestation except 4 periods of 7 d when dietary treatments were imposed on day 27, 55, 83 and 97 of gestation. During the 4 periods, sows were fed 1 of 4 different levels of feed intake: 0.5, 1.0, 1.5 and 2.0×maintenance energy level (0.5M, 1.0M, 1.5M and 2.0M, respectively). Results showed that both BW gain and BF change during gestation for sows on 1.5M (49.7kg and 3.1mm, respectively) and 2.0M (52.5kg and 3.7mm, respectively) levels of feed intake were significantly (P<0.01) greater than sows on 0.5M (26.1kg and -0.1mm, respectively) and 1.0M (35.6kg and 0.1, respectively) levels of feed intake. In contrast, lactation weight gain for sows on 1.5M (3.3kg) and 2.0M (3.4kg) levels of feed intake during 4 short periods of gestation were significantly (P<0.01) less than sows on 0.5M (18.4kg) and 1.0M (11.4kg) levels of feed intake during 4 short periods of gestation, whereas BF loss during lactation for sows on 1.5M (-3.6mm) level of feed intake during 4 short periods of gestation were significantly (P=0.03) higher than sows on 1.0M (-2.1mm) level of feed intake during 4 short periods of gestation. Additionally, average daily feed intake during lactation for sows on 0.5M (6.6kg/d) level of feed intake during gestation tended (P=0.06) to be greater than sows on 2.0M (5.9kg/d) level of feed intake. There were no differences (P>0.1) among 4 levels of feed intake in terms of numbers of total born and weaning piglets. However, both piglet weight at birth (1.46, 1.52, 1.53 and 1.51kg for piglets from sows on 0.5M, 1.0M, 1.5M and 2.0M levels of feed intake during gestation, respectively) and at weaning (6.37, 6.55, 6.64 and 6.38kg for piglets from sows on 0.5M, 1.0M, 1.5M and 2.0M levels of feed intake during gestation, respectively) were maximized at 1.5M level of feed intake. Sows housed in group pens had greater (P<0.01) net BW gain (24.7 vs. 19.2kg) from day 27 of gestation to weaning compared with sows housed in individual stalls. However, there were no differences (P>0.1) between the 2 housing systems in terms of litter size and piglet weight at birth and at weaning. In conclusion, increasing levels of feed intake during 4 short periods of gestation increased BW and BF gain during gestation and led to less BW gain and more BF loss during lactation. Piglet weight at birth and at weaning was maximized at 1.5M level of feed intake. However, housing systems did not affect reproductive performance. Group pen housing system may be beneficial in terms of increased overall BW gain during gestation and lactation.

Effects of cellulase supplementation to corn soybean meal-based diet on the performance of sows and their piglets

A total of 15 primiparous sows (Landrace × Yorkshire) and their litters were used in the current study to evaluate the efficacy of cellulase supplementation on the production performance of sows and piglets. Pigs were randomly allocated into one of three treatments with five replicates per treatment. The dietary treatments were as follows: (i) CON (corn-soybean meal-based control); (ii) EZ1 (CON + 0.05% cellulase); and (iii) EZ2 (CON + 0.10% cellulase). The supplementation of cellulase had no effect (P > 0.05) on body weight and feed intake of lactating sows. At weaning, back fat thickness loss decreased (P = 0.04) linearly in EZ1 and EZ2 treatments. The average daily gain (ADG) of piglets increased (linear P = 0.06, quadratic P = 0.04)) during days 14 to 21 as well as at days 21 to 25 (linear P = 0.03 and quadratic P = 0.01) with the increase in the level of supplemented enzyme. Dry matter and nitrogen digestibility increased (linear P = 0.01) in lactating sows fed EZ1 and EZ2 diet compared with CON. In conclusion, it is suggested that cellulase supplementation to corn-soybean meal based diet exerts beneficial effects to sows in reducing their back fat thickness loss at weaning and also helps to improve nutrient digestibility. It also helped to improve the ADG of piglets.

The addition of a Buttiauxella sp. phytase to lactating sow diets deficient in phosphorus and calcium reduces weight loss and improves nutrient digestibility

Improving the efficiency of P use by pigs is especially important for lactating sows, whose metabolic requirements for P and Ca are high. The effect of a sp. phytase on lactating sow performance and nutrient digestibility was investigated using the combined data set for 6 studies. Treatments included a nutritionally adequate positive control diet (PC), a negative control diet (NC; with an average reduction of 0.16% available phosphorous and 0.15% Ca vs. PC), and NC supplemented with a sp. phytase at 250, 500, 1,000 or 2,000 phytase unit (FTU)/kg, respectively. Phosphorus and Ca deficiency in the NC resulted in significantly higher BW loss compared with the PC. All phytase treatments maintained BW loss at the same level as the PC. Increasing doses of phytase significantly ( < 0.05) reduced sow BW loss and increased energy intake, with improvements most apparent in sows older than parity 5. The positive effects on BW and energy intake were not observed in first-parity sows. This may be a consequence of fewer first parity sows in the data set. The apparent total tract digestibility of DM, OM, and CP were not affected by phytase supplementation. Digestible P and Ca were significantly improved (linear, < 0.0001; quadratic, < 0.0001) by increasing the dose of phytase supplementation. Significantly lower apparent total tract digestibility of energy, Ca, and P was found in the NC treatment vs. the PC treatment, whereas no significant differences were found between phytase treatment and the PC treatment. In conclusion, phytase supplementation at a level of 250 FTU/kg can replace 0.16% available phosphorous and 0.15% Ca; however, increasing the phytase dose can further reduce BW loss in sows fed P- and Ca- deficient diets.

Risk factors associated with the occurrence of the second-litter syndrome in sows in southeastern Mexico

The objective was to estimate the incidence of and to determine the effect of some risk factors on the decrease of litter size at parity 2 of sows in three commercial farms in Yucatan, Mexico. Data on 8,592 farrowing records of 4,296 sows were analyzed using a binomial logistic regression procedure. The model included the fixed effect of farm (1, 2, and 3), year of farrowing (2003–2011), season of farrowing (dry, rainy, and windy), number of pigs born alive at first parity (<9, 9-10, 11-12, and >12 piglets), lactation length (<18, 18–24, and >24 days), and weaning to conception intervals (<4, 4–11, and >11 days). Fifty-five point eight percent of all sows presented a reduced or similar litter size at parity 2. The odds of decrease in the second litter size were 1.56 and 2.01 for farms 2 and 3, respectively. Higher odds were found for sows farrowing during the rainy and dry seasons (1.20 and 1.24, resp.) and for sows with large litters at parity 1 (>12 piglets, odds = 33.2). Sows with weaning to conception intervals <4 days and between 4 and 11 days had higher odds of a decrease in the second litter (1.78 and 2.74 pigs, resp.).

The effect of a non-starch polysaccharide-hydrolysing enzyme (Rovabio® Excel) on feed intake and body condition of sows during lactation and on progeny growth performance

A total of 200 (Large White × Landrace) sows were used in a 39-day study to evaluate the effects of feeding a non-starch polysaccharide (NSP)-hydrolysing enzyme multicomplex (Rovabio(®) Excel) in conjunction with a high- or reduced nutrient-density diet during lactation on sow body condition, feed intake and progeny performance. Eight sows were selected each week for 25 weeks, blocked by parity and BW into groups of four, and within the block randomly assigned to one of the four treatments (n = 50/treatment). Treatments were: (1) LND: low energy (13.14 MJ of DE/kg), low CP (15%) diet; (2) LND + RE: LND with 50 mg/kg NSP-hydrolysing enzyme; (3) HND: high energy (14.5 MJ of DE/kg), high CP (16.5%) diet; and (4) HND + RE: HND with 50 mg/kg NSP-hydrolysing enzyme. Sows were fed treatment diets from day 109 of gestation until the day of subsequent service. Between weaning and re-service, Rovabio(®) Excel addition to LND diets resulted in an increase in energy intake; however, a reduction was observed when supplemented to the HND diet (P < 0.05). The inclusion of Rovabio(®) Excel increased feed and energy intake during week 3 (days 15 to 21) of lactation (P < 0.05). Sows fed diets supplemented with Rovabio(®) Excel had greater back-fat depth at weaning and service (P < 0.05); however, the magnitude of change in back-fat depth during lactation and from farrowing to service was not different between treatments. Feeding the HND diet increased energy intake before farrowing, throughout lactation and during the weaning to service interval (P < 0.01); however, overall, average daily feed intake tended to be reduced (P < 0.10). At service, sows fed the HND diet were heavier than sows fed the LND diet (P < 0.05); however, the magnitude of change in BW between treatments was not different. Feeding the HND diet to sows resulted in a tendency for heavier piglets at birth (P = 0.10) that tended to grow at a faster rate and be heavier at weaning than piglets from sows fed the LND diet (P = 0.06). These results indicate that NSP-degrading enzymes offer minimal benefit to sows and their progeny when fed before and during lactation; however, increasing energy intake of sows during lactation may beneficially affect progeny.

A survey of bone integrity from cull sows in Ireland

The objective of this study was to examine the differences in sow metacarpal properties through various parities and to compare the incidence of locomotory problems between stalled and loose-housed sows. Metacarpals (n = 110) of sows from six farms were collected at slaughter and stored at -20°C. Bones from one forelimb of sows in stalls (n = 36) and loose-housed (n = 20) were collected and their articular surfaces examined for Osteochondrosis Dissecans (OCD), these sows were also scored for lameness pre-slaughter. Metacarpals were CT scanned for cross sectional area and moment of inertia. Cylindrical sections from the diaphysis were used for mechanical testing and calculating bone strength indices. The results show there was little change in bone mineral status throughout the range of parities examined and overall metacarpal integrity was not compromised by multiple production cycles. There were no differences detected in the incidence of lameness or joint pathology between housing systems.