Effect of leg conformation on survivability of Duroc, Landrace, and Large White sows

Sow longevity influences farm economy and can be considered an important indicator of animal welfare. Body features such as leg conformation can play a key role in sow longevity, although little is known about its effect on culling decisions. Within this context, longevity data from 587 Duroc, 239 Landrace, and 217 Large White sows were analyzed with special emphasis on the effect of leg conformation. Sow longevity was analyzed twice for each breed, testing the effect of a subjective overall score for leg conformation, or the presence or absence of 6 specific leg conformation defects. Each preliminary model also included a teat conformation score with 3 levels, farm or origin, backfat thickness at 6 mo of age, and 2 continuous sources of variation, namely the age at the first farrowing and the number of piglets born alive at each farrowing. Overall leg conformation score influenced (P < 0.01) sow longevity in Duroc, Landrace, and Large White sows, with a greater hazard ratio (HR) for poorly conformed sows (1.56, 2.16, and 1.79, respectively) than for well-conformed sows (0.32, 0.66, and 0.68, respectively). Abnormal hoof growth reduced survivability in Duroc (HR = 2.78; P < 0.001) and Landrace sows (HR = 1.88; P < 0.01); the presence of splayed feet (P < 0.05) or bumps and injuries (P < 0.001) increased the risk of culling in Duroc sows (HR = 2.08 and 3.57, respectively), whereas the incidence of straight pastern increased the HR in Large White sows (HR = 2.49; P < 0.01). In all 3 breeds, longevity decreased for plantigrade sows, with a greater HR in Duroc (HR = 3.38; P < 0.001) than in Landrace (HR = 1.53; P < 0.10) and Large White sows (HR = 1.73; P < 0.05). Teat conformation did not influence sow longevity (P > 0.10). Estimates of heritability for longevity in Duroc sows ranged from 0.05 to 0.07 depending on the algorithm applied. Leg conformation had a substantial effect on sow longevity, where an accurate removal of poorly leg-conformed candidate gilts before first mating could improve sow survival and reduce culling costs. These moderate estimates of heritability indicated that survivability of Duroc sows could be genetically improved by direct selection for leg conformation.     

Identification of mutations of zona pellucida glycoprotein (ZP3) and its association with pig reproductive traits

Reproduction is a complex trait, controlled by genetic and environmental factors. Genetic improvement of this trait is important for animal breeders to improve the animal's production efficiency. Apart from genetic factors, animal production can be affected by environmental factors, i.e. the nursing ability of the sow, which is in turn affected directly by effective teat number (teats producing milk normally, TN) and number of piglets born alive (NBA). The objective of this study was to find new mutations, such as single nucleotide polymorphisms (SNPs) from the Zona Pellucida glycoprotein gene (ZP3) using Single Strand Chain Polymorphism (SSCP) and nucleotide sequencing and to investigate association between genetic variations and sow reproductive traits. We identified 13 new SNPs from exon 1, two new SNPs from intron 2, one SNP from intron 6 and a 18 bp (GCACGTGGTCCTCCTGG)‐deletion/insertion from intron 2 of the ZP3 gene. Five out of these mutations were selected to genotype in five different breeds (Small Meishan, Qingping, Duroc, Landrace and Large White) and association with reproductive traits in European breeds (Duroc, Landrace and Large White). The sows with genotype AA had more 1.11 piglets NBA than of the sows with genotype AB (p < 0.05) in the 18 bp deletion/insertion of intron 2, while non‐significant associations between the other mutations and reproductive traits (NBA and TN) were found.     

梅山猪CD14基因多态性及其对部分免疫指标和繁殖性能的关联分析

试验旨在研究梅山猪白细胞分化抗原14（cluster of differentiation antigen 14，CD14）基因多态性及其对部分免疫指标和繁殖性能的遗传效应。采用PCR-RFLP方法对梅山猪CD14基因-61 bp处多态性进行分析，同时对部分重要细胞因子（IL-1β、IL-4、IL-6、IL-8、IL-10、IFN-γ、TNF-α和TGF-β1）水平及繁殖性能（总产仔数、断奶仔猪数、初生窝重和断奶窝重）进行测定，并分析CD14基因多态性与部分免疫指标和繁殖性能的相关性。结果显示，梅山猪CD14基因-61 bp处经BamHⅠ酶切后共检测到3种基因型，分别定义为：AA、AG和GG；χ²适合性检验显示，梅山猪处于Hardy-Weinberg平衡状态（P>0.05）；多态信息含量（PIC）分析显示，梅山猪群体处于中度多态。关联分析结果表明，AA和AG基因型个体的IL-10水平显著高于GG基因型个体（P<0.05）；在初产母猪中，3种基因型间的繁殖性能均无显著差异（P>0.05），而在经产母猪中，AA和AG基因型个体的断奶窝重显著高于GG基因型个体（P<0.05）。本试验结果表明，基于CD14基因-61 bp处多态性对梅山猪进行分子选育时，无论是一般抗病力还是繁殖性能，GG基因型可能均为不利基因型，可以将CD14基因-61 bp处作为一个潜在的遗传标记进行深入系统的验证和分析。     

母猪断配间隔的影响因素分析及其对下一胎繁殖性能的影响

分析影响母猪断配间隔（Weaning-Estrous Interval,WEI）的因素,并分析不同WEI对母猪下一胎繁殖性能的影响。根据新疆某场繁殖母猪2019-2020年12个月的生产分娩记录情况进行统计整理,采用单因素方差分析月份、胎次、品种和哺乳天数对母猪WEI的影响和WEI对母猪下一胎繁殖机能的影响。结果表明：月份间WEI差异显著（P < 0.05）;胎次间WEI差异显著（P < 0.05）;大白初产母猪WEI=4 d发情数最多,而杜洛克与长白猪初产母猪WEI=5 d时最多;3个品种经产母猪均在WEI=4 d时最多;不同哺乳天数下的母猪WEI差异显著（P < 0.05）;大白、长白和杜洛克初产母猪最早可在哺乳20 d、17 d和20 d断奶,经产母猪最早可在哺乳17 d、17 d和16 d断奶而不影响WEI;断奶后第4天和第5天配种,母猪繁殖性能表现最稳定,配种分娩率最高,死胎数最少。     

Farrowing hut design and sow genotype (Camborough-15 vs 25% Meishan) effects on outdoor sow and litter productivity

Performance measures were evaluated for 125 outdoor sows and litters of two crossbred genotypes (Camborough-15 and 25% Meishan) and in two farrowing hut designs (American-style and English-style hut). Contemporary breeding groups of second-parity sows were evaluated in an intensive, outdoor research unit. Sow genotype and hut designs were arranged factorially. Seven complete blocks were evaluated over a 21-wk period. No interactions between environment and genotype were identified for sow and litter productivity. Litters farrowing in the English-style huts weaned 1.5 more (P < .05) piglets per sow (because of a lower preweaning mortality, P = .05) than did litters in the American-style huts. The 25% Meishan weaned 1.7 more (P < .01) pigs per sow than Camborough-15, because of a greater number of piglets born alive. The effects of hut style and genotype were additive and 25% Meishan sows in English-style huts weaned an average (+/- SEM) of 11.1 +/- .83 piglets per sow. The English-style arc hut design may improve outdoor pig production and increase competitiveness of the intensive, outdoor system. The 25% Meishan genotype has potential for increased pigs weaned per litter that must be considered in light of other features of this genotype such as body composition.     

Polymorphism of Mx1 Gene Exon 14 and its Relationship with Reproductive Performance in Meishan Pigs

To analyze the effect of different genotypes in Mx1 gene exon 14 on the reproductive performance in Meishan pigs,PCR-RFLP method was used to amplify DNA and detect the polymorphisms of Mx1 gene exon 14, and the relationship between different genotypes and the reproductive performance was further analyzed by generalized linear model (GLM) in this study.The results of PCR-RFLP showed that there was a G36T mutation on Hin6 Ⅰ restriction site in Mx1 gene exon 14 and three genotypes were detected named as AA,AB and BB,in which BB was a dominant genotype.The results of correlation analysis showed that the reproductive performance of three genotypes in Mx1 gene presented the increasing tendency of BB >AB >AA in total number born (TNB),number born alive (NBA),little size at weaning (LBW),birth weight (BW) and weaning weight (WW) in gilts sows on the whole.Moreover,there was significant difference in TNB,NBA,LBW and WW in gilts sows (P< 0.05).However,there was no significant difference among all reproductive performance in multiparous sows (P >0.05).The results of this study indicated that the polymorphisms of Mx1 gene exon 14 had significantly genetic effects on production performance in Meishan gilts sows instead of multiparous sows.     

梅山猪Mx1基因第14外显子多态性及其与繁殖性能的关联分析

为了探讨梅山猪Mx1基因第14外显子的多态性及其对梅山猪繁殖性能的影响,本研究采用PCR-RFLP方法对所采个体Mx1基因第14外显子进行DNA扩增并检测其多态性,同时利用广义线性模型(GLM)分析不同基因型与繁殖性能间的关系。PCR-RFLP结果表明,梅山猪Mx1基因第14外显子Hin6Ⅰ酶切位点存在G36T突变,共检测到2种等位基因,分别定义为:A、B,其中B基因为优势等位基因;共检测到3种基因型,分别定义为:AA、AB、BB,其中BB基因型为优势基因型;关联分析结果表明,在初产母猪中,总产仔数(TNB)、产活仔数(NBA)、断奶仔猪数(LBW)、初生重(BW)及断奶重(WW)这5个繁殖性状在Mx1基因的3种基因型中的差异均存在BB >AB >AA的趋势,BB基因型为有利基因型;且在总产仔数、产活仔数、断奶仔猪数和断奶重中表现出显著差异性(P<0.05);但在经产母猪中均没有显著差异(P>0.05)。本研究结果提示,Mx1基因第14外显子多态性对梅山猪初产母猪的繁殖性能有显著的遗传效应,而对经产母猪的繁殖性能没有显著的影响。     

Effects of genetic line and supplemental dietary fat on lactation performance of Duroc and Landrace sows.

A total of 124 Duroc and 99 Landrace primiparous and multiparous sows were assigned, within breed and contemporary group, to control (N) or 10% added fat (F) diets on d 105 of gestation based on parity and genetic line (control or selected for improved sow productivity), to determine the effects of genetic line and fat addition to the lactation diet on sow and litter performance. Weekly feed intake was not affected (P greater than .10) by genetic line for Duroc and Landrace sows but feed intake was reduced (P = .08) during wk 1 to 4 for Duroc sows and during wk 1 and 4 for Landrace sows (P less than .05) when they were fed diet F compared with diet N. Select (S)-line Duroc and Landrace sows lost more weight during lactation (P less than .01) than did control (C)-line sows. Select-line Landrace sows lost more backfat during lactation (P less than .05) than did C-line sows. Landrace sows lost less weight during lactation (P less than .05) when fed diet F than when fed diet N. The total number of pigs born, born alive, and alive at 21 d and at weaning were higher (P less than .01) for S-line Duroc sows, and litter size at 21 d and at weaning was higher (P less than .01) for S-line Landrace sows than for C-line litters within each breed. Pig survival from birth to weaning was increased (P = .07) for Duroc sows fed diet F but not for Landrace sows.(ABSTRACT TRUNCATED AT 250 WORDS)     

Between-breed variability of stillbirth and its relationship with sow and piglet characteristics

Litter characteristics at birth were recorded in 4 genetic types of sows with differing maternal abilities. Eighty-two litters from F(1) Duroc x Large White sows, 651 litters from Large White sows, 63 litters from Meishan sows, and 173 litters from Laconie sows were considered. Statistical models included random effects of sow, litter, or both; fixed effects of sow genetic type, parity, birth assistance, and piglet sex, as well as gestation length, farrowing duration, piglet birth weight, and litter size as linear covariates. The quadratic components of the last 2 factors were also considered. For statistical analyses, GLM were first considered, assuming a binomial distribution of stillbirth. Hierarchical models were also fitted to the data to take into account correlations among piglets from the same litter. Model selection was performed based on deviance and deviance information criterion. Finally, standard and robust generalized estimating equations (GEE) procedures were applied to quantify the importance of each effect on a piglet's probability of stillbirth. The 5 most important factors involved were, in decreasing order (contribution of each effect to variance reduction): difference between piglet birth weight and the litter mean (2.36%), individual birth weight (2.25%), piglet sex (1.01%), farrowing duration (0.99%), and sow genetic type (0.94%). Probability of stillbirth was greater for lighter piglets, for male piglets, and for piglets from small or very large litters. Probability of stillbirth increased with sow parity number and with farrowing duration. Piglets born from Meishan sows had a lower risk of stillbirth (P < 0.0001) and were little affected by the sources of variation mentioned above compared with the 3 other sow genetic types. Standard and robust GEE approaches gave similar results despite some disequilibrium in the data set structure highlighted with the robust GEE approach.     

Effects of different gestation housing types on reproductive performance of sows

This study evaluated the effects of different gestation housing types on reproductive performance of sows. A total of 60 sows (218 ± 24 kg body weight) with mixed parity were used. During gestation, 28 sows were housed in groups with electronic sow feeders (space allowance = 1.26 m²/sow) and 32 sows were housed in individual stalls (space allowance = 1.20 m²/sow). Sows from both housing types were moved to farrowing crates on day 109 of gestation and stayed until weaning (18 days post‐farrowing). Typical corn‐soybean meal diets were provided to sows during gestation and lactation. Measurements were reproductive performance of sows at farrowing as well as performance of sows and their litter during lactation. Similar total numbers of piglets born at farrowing were observed for sows gestated in both housing types. However, group‐housed gestation sows had more mummies (0.321 vs. 0.064; P < 0.05) and stillbirths (0.893 vs. 0.469; P = 0.073) at farrowing than individual‐housed gestation sows. Consequently, individual‐housing type had higher percentage of piglets born alive (95.5 vs. 90.4%; P < 0.05) than the group‐housing type. Therefore, improved reproductive performance of sows from individual gestating housing was confirmed in this study.     

Reproductive Performance of Purebred Swedish Landrace and Swedish Yorkshire Sows: I. Seasonal Variation and Parity Influence

The objective of this retrospective study was to investigate the causes of variation in the reproductive performance of purebred Swedish Landrace (L) and Swedish Yorkshire (Y) sows. Data analysed comprised farrowings from 1994 through 1997 from 19 Swedish nucleus herds and included 20 275 litters from 6989 purebred sows (3598 L and 3491 Y). The main traits analysed were litter size, weaning-to-first-service interval (WSI), farrowing rate, remating rate and age at first farrowing. Analysis of variance was used for the statistical analysis of quantitative data. Logistic regression analysis was applied for binary data using the GLIMMIX macro in the SAS program. Factors included in the analyses were breed of sow, breed of boar, parity number, herd-year combination within breed, mating type (natural mating or artificial insemination), lactation length and month of the year. L sows, compared with Y sows, produced larger litters [11.61 vs 11.54 total born/litter (ns) and 10.94 vs 10.58 born alive/litter (P<0.001)] and had a longer WSI (5.5 vs 5.4 days, P<0.001), a higher farrowing rate (82.8 vs 80.9% units, P<0.05) and a lower remating rate (6.2 vs 8.8% units, P<0.001). On average, L sows were younger at first farrowing than Y sows (355.6 vs 368.6 days, P<0.001). The seasonal influence on WSI was greater for primiparous sows than for multiparous sows. Primiparous sows weaned from June to October had a longer WSI than those weaned from January to May or in November (P<0.05). Mating in August resulted in the lowest farrowing rate and the highest remating rate. The seasonal influence on farrowing rate and WSI was more pronounced in Y sows than in L sows. However, season had no significant influence on litter size in either L or Y sows.     

Bioeconomic evaluation of sow longevity and profitability

Sow production indicators, including litter size, litter weight, and the length of time that sows remained in the herd (sow longevity), were used to characterize sow performance and profitability. Sow longevity and production records from 148,568 sows in 32 commercial herds from Central Illinois from January 1995 to May 2001 were analyzed using survival and repeatability models, respectively. The factors studied included sow genetics (32 genetic lines), with eight major lines present in multiple herds, and the combination of herd and year of entry in the herd. The largest difference in longevity between the major genetic lines was approximately one parity. There were differences (P < 0.05) in the instantaneous sow removal rate or hazard from the major lines. These differences constitute evidence that sow longevity could be improved by using replacements from specific genetic lines. The net present value per sow (present value of future cash flows and the present value of the sow) was used to evaluate the effect of sow longevity and production traits on economic returns. Assuming a zero discount rate per parity, genetic lines with longer herd life resulted in greater profit than genetic lines with shorter herd life. This difference was reduced with increasing discount rates and was reversed with high discount rates and low net income per litter. These results suggest that the magnitude of the economic improvement attained through the use of sow genetic lines with longer longevity depends on the economic context under which the evaluation is made.     

Short or Long Day Light Regimes May Not Affect Reproductive Performance in the Sow

The objective of this study was to evaluate the effect of short or long day light regimes on the reproductive performance in the sow. The study comprised approximately 1300 sows and their 3400 breedings in three commercial sow pools, in which a batch farrowing of 40 sows was employed. Each batch remained in the farrowing unit for 8 weeks under either a short day (10 h light, 14 h dark) or a long day (14 h light, 10 h dark) light regime. After weaning and transportation to the central unit, all sows were kept under the long day regime until they were moved back to the farrowing unit. Production results for each individual sow were recorded. The effect of the two different light regimes on the farrowing rate (FR) and on the weaning‐to‐oestrous interval was evaluated using logistic and Poisson regression models, respectively. The light regime affected none of the parameters significantly. The FR in June, July and August did, however, drop below that in December, January and February (OR 0.7, p < 0.05). The FR was affected by the sow pool (p < 0.01). Parity two sows exhibited a lower FR (OR 0.5, p = 0.05) and higher incidence of delayed first oestrus (IRR 2.7, p < 0.01) than did older sows. This study indicates that despite an artificial light regime, sows may still react to changes in season. In conclusion, use of simple light regime to obtain complete control over reproductive performance appears to be difficult.     

Long-term effects of dietary organic and inorganic selenium sources and levels on reproducing sows and their progeny

An experiment evaluated the effects of feeding either a basal non-Se-fortified diet, two Se sources (organic or inorganic) each providing 0.15 and 0.30 ppm Se, or their combination (each providing 0.15 ppm Se) on gilt growth and sow reproductive performance. The experiment was a 2 x 2 + 2 factorial conducted in a randomized complete block design in three replicates. One hundred twenty-six crossbred gilts were started on one of the six treatment diets at 27.6 kg BW. During the grower phase, animals were bled at 30-d intervals with three gilts killed per treatment at 115 kg BW for tissue Se analysis. Fifteen gilts per treatment were bred at 8 mo of age and were continued on their treatment diets for four parities. Sow serum collected within parity was analyzed for Se and glutathione peroxidase (GSH-Px) activity. Tissue Se was determined from five 0-d-old pigs per treatment from fourth-parity sows. Three sows per treatment were killed after the fourth parity for tissue Se analysis. Similar treatment performance responses occurred from 27 to 115 kg BW. Serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased for both Se sources to 0.30 ppm Se during the grower and reproductive periods. Serum Se and GSH-Px activity decreased from 70 to 110 d postcoitum in all treatment groups, but increased at weaning (P < 0.01) in the Se-fortified groups. The number of pigs born (total, live) increased (P < 0.05) with the 0.15 ppm Se level for both Se sources. Tissue and total body Se content of 0-d-old pigs increased with Se level (P < 0.01) and also when the organic Se source (P < 0.01) was fed to the sow. When sows were fed either Se source, pig serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased at weaning. Colostrum and milk Se concentrations increased (P < 0.01) with Se level for both Se sources, but were substantially greater (P < 0.01) when sows were fed organic Se. The combination of Se sources had sow milk and tissue Se values that were similar to those of sows milk and fed 0.15 ppm organic Se. The fourth-parity sows had greater tissue Se concentrations when organic Se level was increased (P < 0.01), more so than when sows were fed inorganic Se. These results suggest that both Se sources resulted in similar sow reproductive performances at 0.15 ppm Se, but sows fed the organic Se source had a greater transfer of Se to the neonate, colostrum, milk, weaned pig, and sow tissues than sows fed inorganic Se.     

胎次对杜洛克、长白和大白母猪繁殖性能的影响

为了研究胎次对杜洛克、长白和大白母猪繁殖性能的影响,根据江苏省某国家级生猪核心育种场2009-2011年出生的繁殖母猪资料,分别选取128头杜洛克、681头长白和610头大白母猪共7280窝生产数据,统计分析不同胎次母猪的总产仔数、产活仔数、断奶仔猪数、初生窝重及校正21日龄窝重。此外,依据胎次将母猪分为3个繁殖阶段（1～2胎、3～6胎及7～8胎）来探究品种差异对母猪繁殖性能的影响。结果表明：胎次对母猪繁殖性能有显著影响（P<0.05）,母猪1～4胎的总产仔数、产活仔数、断奶仔猪数及初生窝重随胎次呈增加趋势,第4胎达到高峰,且显著高于其他胎次（P<0.05）;3～6胎繁殖性能较好,7胎之后出现迅速下降趋势;除在第4胎略有下降外,其他胎次的校正21日龄窝重随胎次递增。品种对母猪繁殖性能的影响显著（P<0.05）,长白和大白母猪的繁殖性能均极显著高于杜洛克母猪（P<0.01）;长白母猪的产活仔数和校正21日龄窝重显著高于大白母猪（P<0.05）,2个品种其他繁殖性能无显著差异（P＞0.05）。综上所述,杜洛克、长白和大白母猪的最佳繁殖胎次为3～6胎,长白猪的繁殖性能总体上优于大白猪,就本试验所在的育种场而言,长白猪可能更适合作为二元母猪生产中的母本。     

Probiotic supplementation improves reproductive performance of unvaccinated farmed sows infected with porcine epidemic diarrhea virus

We investigated if probiotic supplementation could improve the health and reproductive performance of unvaccinated lactating sows infected with porcine epidemic diarrhea (PED) virus. Twenty unvaccinated pregnant sows were equally allocated to probiotic‐supplemented (P) and control (C) groups. For the experiment, 15 g/day of probiotic compound BIO‐THREE PZ was given to P sows. Reproductive performance was checked daily. The number of neonates fostered by each sow was maintained at eight throughout the experiment. Individual milk production post‐parturition was measured twice. Milk protein and fat ratios were determined by a milk analyzer. Total immunoglobulin (Ig) A and G concentrations were measured by ELISA. At day 7 post‐parturition, the body weight of P sows was 10 kg higher than that of C sows, and at day 3 post‐parturition, P sows produced more milk (+2 kg) and had a higher IgA concentration in whey than did C sows (p < .05). Finally, unlike C sows, P sows tended to return to estrus faster, and had larger piglets at birth with a lower mortality percentage during early days of suckling. In conclusion, probiotic compound BIO‐THREE PZ helped strengthen the immune system of unvaccinated, PED‐infected sows and improved their reproductive performance.     

Sow and litter response to supplemental dietary fat in lactation diets during high ambient temperatures

The objective of this experiment was to determine the impact of supplemental dietary fat on total lactation energy intake and sow and litter performance during high ambient temperatures (27 ± 3°C). Data were collected from 337 mixed-parity sows from July to September in a 2,600-sow commercial unit in Oklahoma. Diets were corn-soybean meal-based with 7.5% corn distillers dried grains with solubles and 6.0% wheat middlings and contained 3.24 g of standardized ileal digestible Lys/Mcal of ME. Animal-vegetable fat blend (A-V) was supplemented at 0, 2, 4, or 6%. Sows were balanced by parity, with 113, 109, and 115 sows representing parity 1, 2, and 3 to 7 (P3+), respectively. Feed disappearance (subset of 190 sows; 4.08, 4.18, 4.44, and 4.34 kg/d, for 0, 2, 4, and 6%, respectively; P < 0.05) and apparent caloric intake (12.83, 13.54, 14.78, and 14.89 Mcal of ME/d, respectively; P < 0.001) increased linearly with increasing dietary fat. Gain:feed (sow and litter BW gain relative to feed intake) was not affected (P = 0.56), but gain:Mcal ME declined linearly with the addition of A-V (0.16, 0.15, 0.15, and 0.14 for 0, 2, 4, and 6%, respectively; P < 0.01). Parity 1 sows (3.95 kg/d) had less (P < 0.05) feed disappearance than P2 (4.48 kg/d) and P3+ (4.34 kg/d) sows. Body weight change in P1 sows was greater (P < 0.01) than either P2 or P3+ sows (-0.32 vs. -0.07 and 0.12 kg/d), whereas backfat loss was less (P < 0.05) and loin depth gain was greater (P < 0.05) in P3+ sows compared with P1 and P2 sows. Dietary A-V improved litter ADG (P < 0.05; 1.95, 2.13, 2.07, and 2.31 kg/d for 0, 2, 4, and 6% fat, respectively) only in P3+ sows. Sows bred within 8 d after weaning (58.3, 72.0, 70.2, and 74.7% for 0, 2, 4, and 6%, respectively); conception rate (78.5, 89.5, 89.2, and 85.7%) and farrowing rate (71.4, 81.4, 85.5, and 78.6%) were improved (P < 0.01) by additional A-V, but weaning-to-breeding interval was not affected. Rectal and skin temperature and respiration rate of sows were greater (P < 0.002) when measured at wk 3 compared with wk 1 of lactation, but were not affected by A-V addition. Parity 3+ sows had lower (P < 0.05) rectal temperature than P1 and P2 sows, and respiration rate was reduced (P < 0.001) in P1 sows compared with P2 and P3+ sows. In conclusion, A-V improved feed disappearance and caloric intake, resulting in improved litter weight gain and subsequent reproductive performance of sows; however, feed and caloric efficiency were negatively affected.     

Immune status of PIC Camborough-15 sows, 25% Meishan sows, and their offspring kept indoors and outdoors

Newer genetic lines of pigs are being used in indoor and outdoor production systems. The objectives of Exp. 1 were to describe the effects of the maternal sow line genotype, environment (indoor vs outdoor), and the genotype x environment interactions on blood hemoglobin (Hb), immunoglobulin G (IgG) concentrations, white blood cell (WBC) numbers, lymphocyte transformation/blastogenesis (LTA), natural killer (NK) cell activity, neutrophil chemotaxis, cortisol concentrations, and leukocyte differentials. Studies were performed using two genotypes: PIC Experimental-94 (Exp-94, an experimental line containing 25% Meishan) and PIC Camborough-15 (C-15). The Exp-94 sows had lower LTA at 0.2 microg/mL mitogen than the C-15 sows, whereas Exp-94 sows had higher NK cytotoxicity than the C-15 sows. When indoors, the two genotypes showed similar neutrophil chemotaxis. When outdoors, the C-15 genotype had higher (P < .01) neutrophil chemotaxis than the Exp-94 sows. The other immune measures were statistically similar for the two genotypes for each environment and for the genotype x environment interaction of sows. Experiment 2 sought to determine the effects of genotype on the immune system of nursery-age offspring of the experimental lines. Each sow line was bred to a common PIC 405 boar line. The Exp-94 x 405 pigs had elevated WBC numbers than C-15 x 405 pigs. The social status of the Exp-94 x 405 or the C-15 x 405 pigs showed no effect on any of the immune measures studied. The other immune measures were statistically similar for the two lines of pigs. The Exp-94 line had marginally increased NK activity but reduced lymphocyte blastogenesis and neutrophil chemotaxis compared with the C-15 line.     

Endocrine relationships of Meishan and White composite females after weaning and during the luteal phase of the estrous cycle

Endocrine differences between European crossbred and Chinese Meishan females have been somewhat modest. Indwelling jugular cannulas were placed in Meishan (n = 7) and White composite (n = 6) multiparous sows before weaning, and blood was sampled from 4 h before to 240 h after removal of litters. Temporal changes in FSH, triiodothyronine (T3), and tetraiodothyronine (T4) after weaning differed between Meishan and White composite sows. Plasma cortisol concentrations were higher in Meishan sows than in White composite sows (P < 0.01), but there were no temporal differences between breeds after weaning. Other hormones monitored (prolactin, GH, IGF-I, and inhibin) were not different between breeds. In the second experiment, Meishan gilts (n = 7) and sows (n = 7) and White composite sows (n = 9) were cannulated during the luteal phase of the estrous cycle and sampled after treatments consisting of GnRH (15 and 150 ng/kg BW), ovariectomy, estradiol cypionate challenge after ovariectomy (10 microg/kg BW), and GnRH antagonist. In response to GnRH challenge, White composite sows had elevated (P < 0.05) concentrations of gonadotropins compared with Meishan. Cortisol concentrations were elevated in Meishan as compared with White composite females (P < 0.01) but unaffected by GnRH treatment. After ovariectomy, LH concentrations increased 3 h sooner in White composite than in Meishan females. After GnRH antagonist, declines in gonadotropins were comparable in both breeds, but LH increased in Meishan females by 20 h but not until after 54 h in White composite females. White composite females demonstrated only a short decline in FSH in response to the GnRH antagonist, but Meishan females had a prolonged decline in FSH concentrations. Consistently elevated cortisol concentrations in Meishan females may positively impact ovarian function; thus, the assumption that high plasma cortisol concentration as an index of stress that impairs reproductive function should be reevaluated in swine. There were few endocrine differences that would relate to or explain increased ovulation rates found in the Meishan breed; thus, other mechanisms must exist to explain the increase in ovarian function in the Meishan breed.     

Effects of Inulin Supplementation in Low‐ or High‐Fat Diets on Reproductive Performance of Sows and Antioxidant Defence Capacity in Sows and Offspring

This experiment was conducted to investigate the effects of inulin supplementation in low‐ or high‐fat diets on both the reproductive performance of sow and the antioxidant defence capacity in sows and offspring. Sixty Landrace × Yorkshire sows were randomly allocated to four treatments with low‐fat diet (L), low‐fat diet containing 1.5% inulin (LI), high‐fat diet (H) and high‐fat diet containing 1.5% inulin (HI). Inulin‐rich diets lowered the within‐litter birth weight coefficient of variation (CV, p = 0.05) of piglets, increased the proportion of piglets weighing 1.0–1.5 kg at farrowing (p < 0.01), reduced the loss of body weight (BW) and backfat thickness (BF) during lactation (p < 0.05) and decreased the duration of farrowing as well as improved sow constipation (p < 0.05). Sows fed fat‐rich diets gained more BW during gestation (p < 0.01), farrowed a greater number of total (+1.65 pigs, p < 0.05) and alive (+1.52 pigs p < 0.05) piglets and had a heavier (+2.06 kg, p < 0.05) litter weight at birth as well as a decreased weaning‐to‐oestrous interval (WEI, p < 0.01) compared with sows fed low‐fat diets. However, it is worth noting that the H diet significantly decreased the serum activities of superoxide dismutase (T‐SOD) and glutathione peroxidase (GSH‐Px) and increased the serum malondialdehyde (MDA) levels in sows and piglets (p < 0.05). In contrast, HI diet enhanced the activities of T‐SOD and GSH‐Px and decreased the serum MDA concentrations (p < 0.05) in sows and piglets. In summary, the fat‐rich diets fed to sows during gestation had beneficial effects on reproductive performance, but aggravated the oxidative stress in sow and piglets. Inulin‐rich diets fed to sow during gestation had beneficial effects on within‐litter uniformity of piglet birthweight and enhanced the antioxidant defence capacity of sows and piglets.