Duroc Gilts Research Articles

Modeling microRNA-driven post-transcriptional regulation using exon-intron split analysis in pigs.

The contribution of microRNAs (miRNAs) to mRNA post-transcriptional regulation has often been explored by the post hoc selection of downregulated genes and determining whether they harbor binding sites for miRNAs of interest. This approach, however, does not discriminate whether these mRNAs are also downregulated at the transcriptional level. Here, we have characterized the transcriptional and post-transcriptional changes in mRNA expression in two porcine tissues: gluteus medius muscle of fasted and fed Duroc gilts and adipose tissue of lean and obese Duroc-Göttingen minipigs. Exon-intron split analysis of RNA-seq data allowed us to identify downregulated mRNAs with high post-transcriptional signals in fed or obese states, and we assessed whether they harbor binding sites for upregulated miRNAs in any of these two physiological states. We found 26 downregulated mRNAs with high post-transcriptional signals in the muscle of fed gilts and 21 of these were predicted targets of miRNAs upregulated in fed pigs. For adipose tissue, 44 downregulated mRNAs in obese minipigs displayed high post-transcriptional signals, and 25 of these were predicted targets of miRNAs upregulated in the obese state. These results suggest that the contribution of miRNAs to mRNA repression is more prominent in the skeletal muscle system. Finally, we identified several genes that may play relevant roles in the energy homeostasis of the pig skeletal muscle (DKK2 and PDK4) and adipose (SESN3 and ESRRG) tissues. By differentiating transcriptional from post-transcriptional changes in mRNA expression, exon-intron split analysis provides a valuable view of the regulation of gene expression, complementary to canonical differential expression analyses.

Effects of the slaughter weight of non-lean finishing pigs on their carcass characteristics and meat quality.

The present study aimed to assess the feasibility of increasing the slaughter weight (SW) of non-lean finishing pigs to improve their meat quality. A total of 36 (Landrace × Yorkshire) × Duroc gilts and barrows were slaughtered at 115 (Av), 125 (Hi), or 135 (XHi) kg, followed by physicochemical analyses and sensory evaluation on their longissimus dorsi (LD) and Semimembranosus (SM) muscles. Backfat thickness was greater (p < 0.05) for the XHi (31.2 mm) and Hi (29.3 mm) groups than for Av (25.0 mm). Dressing percentage and yield of the belly per whole carcass were also slightly greater for XHi and Hi vs. Av. The intramuscular fat (IMF) content of SM was greater for XHi (2.64%) than for Av (1.83%) and Hi (2.04%) and also was correlated with SW (r = 0.55). The pH value, lightness, redness, drip loss, shear force, and moisture and protein contents of LD and SM, as well as IMF content of LD, were unaffected by SW. Percentages of 14:0, 16:0, and total saturated fatty acids (FA) were less for Hi and XHi vs. Av in SM, those of total unsaturated FA, 18:2, 20:4, and n-6 being opposite; FA composition of LM was not influenced by SW except for a reduced 18:0 percentage for XHi vs. Av. The sensory score was less for XHi vs. Av for odor in fresh LD and SM, and less for Hi and XHi vs. Av for aroma in fresh LM; scores for color, drip loss, marbling, and acceptability were unaffected by SW. As for cooked muscles, none of the scores for color, aroma, flavor, juiciness, tenderness, and acceptability was affected by SW, except for a greater LD color score for Hi and XHi vs. Av. Collectively, the results suggested that the increased yield of the carcass and belly due to increased SW is outbalanced negatively by excessive backfat deposition in production efficiency, whereas the SW increase exerts little influence on overall sensory quality of fresh or cooked meat. Production of non-lean market pigs overweighing 115 kg therefore will be uneconomical unless consumers pay a substantial premium for the over-fattened pork.

Estimation of Genetic Parameters for Pork Quality, Novel Carcass, Primal-Cut and Growth Traits in Duroc Pigs.

Simple SummaryThere is a growing interest in worldwide swine breeding programs to genetically select for pork quality and primal cuts in addition to the traditional growth and carcass leanness traits. Accurate population genetic parameters are needed to estimate correlated responses to selection and incorporate novel traits in the selection objective. Therefore, we estimated heritabilities and genetic correlations for 39 pork quality, growth and carcass traits in Duroc pigs. In general, moderate and favorable genetic correlations were observed between pork quality (e.g., loin color and marbling scores) and carcass traits. Additionally, moderate to low correlations were found among pork quality, growth and carcass traits. Our findings suggest that pig breeders can successfully incorporate pork quality and novel carcass traits in the selection objectives without undesirable impacts upon growth rate and carcass leanness.More recently, swine breeding programs have aimed to include pork quality and novel carcass (e.g., specific primal cuts such as the Boston butt or belly that are not commonly used in selection indexes) and belly traits together with growth, feed efficiency and carcass leanness in the selection indexes of terminal-sire lines, in order to efficiently produce pork with improved quality at a low cost to consumers. In this context, the success of genetic selection for such traits relies on accurate estimates of heritabilities and genetic correlations between traits. The objective of this study was to estimate genetic parameters for 39 traits in Duroc pigs (three growth, eight conventional carcass (commonly measured production traits; e.g., backfat depth), 10 pork quality and 18 novel carcass traits). Phenotypic measurements were collected on 2583 purebred Duroc gilts, and the variance components were estimated using both univariate and bivariate models and REML procedures. Moderate to high heritability estimates were found for most traits, while genetic correlations tended to be low to moderate overall. Moderate to high genetic correlations were found between growth, primal-cuts and novel carcass traits, while low to moderate correlations were found between pork quality and growth and carcass traits. Some genetic antagonisms were observed, but they are of low to moderate magnitude. This indicates that genetic progress can be achieved for all traits when using an adequate selection index.

Discovery and annotation of novel microRNAs in the porcine genome by using a semi-supervised transductive learning approach

Despite the broad variety of available microRNA (miRNA) prediction tools, their application to the discovery and annotation of novel miRNA genes in domestic species is still limited. In this study we designed a comprehensive pipeline (eMIRNA) for miRNA identification in the yet poorly annotated porcine genome and demonstrated the usefulness of implementing a motif search positional refinement strategy for the accurate determination of precursor miRNA boundaries. The small RNA fraction from gluteus medius skeletal muscle of 48 Duroc gilts was sequenced and used for the prediction of novel miRNA loci. Additionally, we selected the human miRNA annotation for a homology-based search of porcine miRNAs with orthologous genes in the human genome. A total of 20 novel expressed miRNAs were identified in the porcine muscle transcriptome and 27 additional novel porcine miRNAs were also detected by homology-based search using the human miRNA annotation. The existence of three selected novel miRNAs (ssc-miR-483, ssc-miR484 and ssc-miR-200a) was further confirmed by reverse transcription quantitative real-time PCR analyses in the muscle and liver tissues of Göttingen minipigs. In summary, the eMIRNA pipeline presented in the current work allowed us to expand the catalogue of porcine miRNAs and showed better performance than other commonly used miRNA prediction approaches. More importantly, the flexibility of our pipeline makes possible its application in other yet poorly annotated non-model species.

PSVIII-37 Estimation of genetic parameters for novel meat quality and carcass traits in Duroc pigs

Abstract In recent years, swine breeding programs have turned their selection attentions from focusing mostly on growth, feed efficiency and percent fat towards including meat quality and carcass traits with aims to efficiently produce nutritious and tasty meat to attend a growing demand for pork. In this context, the success of genetic selection for such traits relies on several factors, especially the heritability (h2) of the traits included in the selection indexes. Therefore, this study aimed to estimate genetic parameters for seven meat quality and carcass traits in Duroc pigs, including: meat lightness (L*), loin pH (pH), marbling (MARB), untrimmed belly weight (UBLW), untrimmed ham weight (UHW), untrimmed loin weight (ULW), and untrimmed shoulder weight (USW). Phenotypic measurements were collected on 2,857 purebred Duroc gilts from a Terminal Sire line. The pedigree-based relationship matrix included 5,316 animals and genetic parameters were estimated using univariate models under the REML approach. The traits studied here were shown to be moderately to highly heritable (h2 estimates were 0.32, 0.42, 0.47, 0.35, 0.24, 0.28, and 0.28 for L*, pH, MARB, UBLW, UHW, ULW, and USW, respectively). Our findings suggest that these traits are under genetic control, and thus, they can be genetically improved if included in selection schemes. The next step will be to estimate the genetic correlation between those traits (among themselves and with other traits), as well as alternatives to efficiently incorporate these traits in the selection indexes.

Relationships between Single Nucleotide Polymorphism Markers and Meat Quality Traits of Duroc Breeding Stocks in Korea.

This study was conducted to determine the relationships of five intragenic single nucleotide polymorphism (SNP) markers (protein kinase adenosine monophosphate-activated γ3 subunit [PRKAG3], fatty acid synthase [FASN], calpastatin [CAST], high mobility group AT-hook 1 [HMGA1], and melanocortin-4 receptor [MC4R]) and meat quality traits of Duroc breeding stocks in Korea. A total of 200 purebred Duroc gilts from 8 sires and 40 dams at 4 pig breeding farms from 2010 to 2011 reaching market weight (110 kg) were slaughtered and their carcasses were chilled overnight. Longissimus dorsi muscles were removed from the carcass after 24 h of slaughter and used to determine pork properties including carcass weight, backfat thickness, moisture, intramuscular fat, pH24h, shear force, redness, texture, and fatty acid composition. The PRKAG3, FASN, CAST, and MC4R gene SNPs were significantly associated with the meat quality traits (p<0.003). The meats of PRKAG3 (A 0.024/G 0.976) AA genotype had higher pH, redness and texture than those from PRKAG3 GG genotype. Meats of FASN (C 0.301/A 0.699) AA genotype had higher backfat thickness, texture, stearic acid, oleic acid and polyunsaturated fatty acid than FASN CC genotype. While the carcasses of CAST (A 0.373/G 0.627) AA genotype had thicker backfat, and lower shear force, palmitoleic acid and oleic acid content, they had higher stearic acid content than those from the CAST GG genotype. The MC4R (G 0.208/A 0.792) AA genotype were involved in increasing backfat thickness, carcass weight, moisture and saturated fatty acid content, and decreasing unsaturated fatty acid content in Duroc meat. These results indicated that the five SNP markers tested can be a help to select Duroc breed to improve carcass and meat quality properties in crossbred pigs.

ANTE-MORTEM FORMATION OF THE QUALITATIVE CHARACTERISTICS OF ENVIRONMENTALLY FRIENDLY MEAT RAW MATERIAL BY INTENSIFICATION OF THE MECHANISMS OF THE METABOLIC PROCESSES IN GILTS

Abstract In order to reduce the time of feeding, increase the intensity of weight gain without hormones, antibiotics, anabolic drugs, as well as to obtain high-quality meat with marble structure, the authors studied the influence of ovarioectomy on the intensification of the metabolic processes in gilts. The experiments were carried out in the FGUP “Mummovskoe” – the educational experimental enterprise of the Russian State Agrarian University - Moscow Timiryazev Agricultural Academy (RSAU – MAA named after K.A. Timiryazev), in the Atkarsky district of the Saratov region. Two groups of Duroc gilts (10 animals each) raised under the same conditions were studied. As a result of the experiment, the influence of ovariectomy on the level of insulinlike growth factor-1 (IGF-1) and indicators of metabolic processes in gilts were established. It is confirmed that stimulation of the the somatotropin/insulin-like growth factor (ST-IGF) system along with hereditary factors and the characteristics of feeding contributes to the development of muscle tissue. Stimulation of ST secretion with insulin-like growth factor facilitates the development of muscle tissue. An increase in IGF-1 level leads to the development of new muscle fibers and muscle hyperplasia. After surgery, the major factors of changes in meat and feeding indicators in gilts were the rise in the metabolic activity of muscle tissue and fat metabolism, enhancement of production of IGF-1, which has insulin-like action and ensures activation of the processes of cell proliferation and differentiation. Increase in IGF-1 level had a positive impact on meat productivity, chemical and biochemical composition of pork. Simultaneous triggering of the systemic catabolic and local anabolic reactions in gilts after ovariectomy contributed to obtaining higher nutritional value of meat.

Variance components of aggressive behavior in genetically highly connected Pietrain populations kept under two different housing conditions1

Mixing of unfamiliar pigs is a standard management procedure in commercial pig production and is often associated with a period of intense and physically damaging aggression. Aggression is considered a problem for animal welfare and production. The objective of the present paper was to investigate the genetic background of aggressive behavior traits at mixing of unfamiliar gilts under 2 different housing conditions. Therefore, a total of 543 purebred Pietrain gilts, from 2 nucleus farms (farm A: n = 302; farm B: n = 241) of 1 breeding company, were tested at an average age of 214 d (SD 12.2 d) for aggressive behavior by 1 observer. Observations included the frequencies of aggressive attack and reciprocal fighting during mixing with unfamiliar gilts. On farm A 41% of the gilts were purebred Pietrains, whereas 59% were purebred Landrace or Duroc gilts. On the farm B 42% of the gilts were purebred Pietrains, and 58% purebred Large White gilts. The average size of the newly mixed groups of gilts was 28 animals on farm A and 18 animals on farm B. The Pietrain gilts from the 2 herds were genetically closely linked. They were the offspring of 96 sires, with 64% of these sires having tested progeny in both farms. There were clear differences in the housing of the animals between the 2 farms. The test pen on farm A had a solid concrete floor littered with wooden shavings and was equipped with a dry feeder. On farm B there was a partly slatted floor, and the gilts were fed by an electronic sow feeder. Mean space allowance was 2.6 m(2)/gilt on farm A and 3.9 m(2)/gilt on farm B. Although large interindividual differences existed, gilts from farm B performed numerically more aggressive attack (mean 1.12, SD 1.42 vs. mean 0.71, SD 1.20) and reciprocal fighting (mean 0.78, SD 0.98 vs. mean 0.44, SD 0.82) when compared with gilts from farm A. The heritabilities and additive genetic variances for behavioral traits were estimated with a linear animal model and were on a low level in farm A (h(2) = 0.11, SE = 0.07, and σ(2)a = 0.12 for aggressive attack and h(2) = 0.04, SE = 0.07, and σ(2)a = 0.02 for reciprocal fighting) and on a moderate level in farm B (h(2) = 0.29, SE = 0.13, and σ(2)a = 0.44 for aggressive attack and h(2) = 0.33, SE = 0.12, and σ(2)a = 0.27 for reciprocal fighting). For both aggressive attack and reciprocal fighting, genetic correlation of the same trait between farm A and farm B was 1.0. Therefore, aggressive behavior does not seem to be influenced by genotype × environment interactions. Under these circumstances aggressions in group housing can be reduced by genetic selection against aggressive behavior. Therewith, the welfare and health of sows will ultimately increase.

Transcriptome analysis of porcine M. semimembranosus divergent in intramuscular fat as a consequence of dietary protein restriction

BackgroundIntramuscular fat (IMF) content is positively correlated with aspects of pork palatability, including flavour, juiciness and overall acceptability. The ratio of energy to protein in the finishing diet of growing pigs can impact on IMF content with consequences for pork quality. The objective of this study was to compare gene expression profiles of Musculus semimembranosus (SM) of animals divergent for IMF as a consequence of protein dietary restriction in an isocaloric diet. The animal model was derived through the imposition of low or high protein diets during the finisher stage in Duroc gilts. RNA was extracted from post mortem SM tissue, processed and hybridised to Affymetrix porcine GeneChip® arrays.ResultsIMF content of SM muscle was increased on the low protein diet (3.60 ± 0.38% versus 1.92 ± 0.35%). Backfat depth was also greater in animals on the low protein diet, and average daily gain and feed conversion ratio were lower, but muscle depth, protein content and moisture content were not affected. A total of 542 annotated genes were differentially expressed (DE) between animals on low and high protein diets, with 351 down-regulated and 191 up-regulated on the low protein diet. Transcript differences were validated for a subset of DE genes by qPCR. Alterations in functions related to cell cycle, muscle growth, extracellular matrix organisation, collagen development, lipogenesis and lipolysis, were observed. Expression of adipokines including LEP, TNFα and HIF1α were increased and the hypoxic stress response was induced. Many of the identified transcriptomic responses have also been observed in genetic and fetal programming models of differential IMF accumulation, indicating they may be robust biological indicators of IMF content.ConclusionAn extensive perturbation of overall energy metabolism in muscle occurs in response to protein restriction. A low protein diet can modulate IMF content of the SM by altering gene pathways involved in lipid biosynthesis and degradation; however this nutritional challenge negatively impacts protein synthesis pathways, with potential consequences for growth.

Excess pregnancy weight gain and early energy‐rich environment in swine program offspring for indications of metabolic syndrome

Many pregnancies in the United States result in weight gain in excess of recommendations. Few data exist on the impact of maternal weight gain on offspring despite evidence demonstrating that early life environment precipitates risks for metabolic syndrome. Excessive gestation weight gain and postnatal diet were assessed using a swine model of human health. Offspring from Landrace x Duroc gilts fed a normal (mNE) or a high energy diet (mHE) to induce a 30% increase in gestation weight gain were weaned to either a normal (wNE) or high energy (wHE) diet. At 3 months of age piglets fed wHE had increased (P &lt; 0.05) backfat compared with wNE and suppressed (P &lt; 0.05) hepatic and intestine (1.51 vs. 0.48 and 0.85 vs. 0.47, respectively for wNE vs. wHE) PEPCK‐C abundance. Intestine PGC‐1α abundance was significantly lower in offspring from mHE gilts (0.94 vs. 0.60 for mNE vs. mHE). Offspring from mHE gilts weaned onto a wHE diet had elevated (P &lt; 0.05) blood glucose (102 vs. 64 mg/dl), insulin (0.10 vs. 0.21 ng/ml) and lower NEFAs (0.62 vs. 0.31 mmol/L) compared to mHEwNE offspring. Postnatal wHE did not induce the same metabolic perturbations in the mNE offspring (GLU 70 vs. 80 mg/dl, ILN 0.16 vs. 0.13 mg/dl, NEFA 0.43 vs. 0.43 mmol/L for mNEwNE vs. mNEwHE). These data show gestational weight gain of 30% in excess of recommendations and a nutrient‐rich postnatal environment precipitate indications of metabolic syndrome.Grant Funding Source : Showalter Trust Fund

Effects of Dietary Energy Level on Growth Efficiency and Carcass Quality Traits of Finishing Pigs

ABSTRACT A total of 96 non-lean-type (Yorkshire ×Landrace) × Duroc gilts and barrows weighing approximately 80 kg were randomly allocated to 24 pens under a 2 (sex) × 3 [diet; 3.4, 3.2, and 3.0 Mcal DE/kg {‘high’-, ‘medium’-, and ‘low’-energy diets (HE, ME, and LE), respectively}] factorial arrangement of treatments. All animals were slaughtered approximately at 115 kg, after which carcass quality traits and grades and physicochemical and sensory characteristics of the loin related to meat quality were analyzed. The ADG and gain:feed were not affected by the sex or dietary treatment, whereas ADFI was greater in the ME vs HE group. Backfat thickness was greater in barrows vs gilts and also in ME and HE vs LE only in barrows. Enumerated carcass marbling and quality grade, which were highly correlated (r=0.56; P<0.01), were greater in barrows vs gilts. Physicochemical characteristics including the color, pH, drip loss and contents of moisture, protein, and fat of fresh loin, as well as sensory characteristics of fresh and cooked loin, were not affected by the sex or dietary treatment, except for shear force for cooked loin which was greater (P<0.05) in LE and ME vs HE. In conclusion, it is thought that ME is comparable to HE in terms of the effect on growth and carcass quality of finishing pigs, but that the relative effect of LE vs ME needs to be further studied. (

Cortisol-binding globulin and meat quality in five European lines of pigs1

The gene (Cbg) encoding cortisol-binding globulin (CBG) has been proposed as a candidate gene to explain genetic variation in cortisol secretion and carcass composition in pigs. The objective of this study was to evaluate the association between CBG and pork quality in 5 European breeding lines, Piétrain, Large White (LW), and Landrace purebred lines, a Duroc synthetic line, and a Meishan (MS) x LW advanced intercross. Cortisol-binding globulin maximum binding capacity (CBG-Bmax) was twice as high (P < 0.05) in MS x LW pigs compared with the other lines. There was no (P > or = 0.364) association between CBG-Bmax and carcass quality traits in Piétrain gilts, but CBG-Bmax was associated with increased loin yields in LW (P = 0.010) and Landrace (P = 0.103) gilts, decreased ham yields (P = 0.082) in Duroc gilts, and increased fat depth (P = 0.064) and leaf fat (P = 0.001) in MS x LW gilts. There was no association between CBG-Bmax and pork quality traits in Piétrain (P > or = 0.269) and Duroc (P > or = 0.114) gilts. Conversely, CBG-Bmax was associated with lighter (higher L* values; P < 0.05) pork in Land-race gilts, as well as lower (P < or = 0.055) ultimate pH in the LM and semimembranosus, and a tendency for lower (P = 0.095) L* values of pork from LW gilts. Within MS x LW pigs, CBG-Bmax was associated with increased drip loss (P = 0.001) and decreased i.m. fat in the semimembranosus (P = 0.005). Because drip loss is an economically important pork quality trait, results of this study could be used in the selection of improved water-holding capacity of pork from synthetic lines involving the MS breed.

Short communication. Lactation performance of Duroc gilts under the single farrowing production system

Twelve Duroc gilts were used in order to study production and composition of milk during the lactation period and the litter performance under the single farrowing production system. Estrus was induced using PG-600 (400 IU of pregnant mare serum gonadotrophin + 200 IU of human corionic gonadotrophin) and the females were artificially inseminated at 171 +/- 6 d and 95.1 +/- 5.6 kg live weight. Daily milk production was determined according to the weigh-suckle-weigh technique at 1, 7, 14 and 21 d of lactation and colostrum and mature milk samples were collected at farrowing and on 8, 15 and 22 d of lactation. The sows net gain during pregnancy was of 49.1 +/- 7.1 kg and during lactation their feed intake was of 3.4 +/- 0.3 kg dE–1 and their weight loss was 5.83 +/- 2.5 kg. The production of milk increased in a linear way through the lactation period and the average daily production was very low (4.29 +/- 0.7 kg). The contents of colostrum dry matter, gross energy and proteinwere higher than the mature milk but lower regarding fat and lactose. Dry matter, gross energy, protein and lactose contents in milk did not significantly vary during lactation. Nevertheless, an increase in fat content was found in the eighth day of lactation. The average daily gain in piglets was 130.4 +/- 31.5 g and the milk conversion ratio was 3.47 +/- 0.39 kg kgE–1. The protein level in lactation feed did not have a significant influence on sows and piglets performances.

Vaginal contraceptive activity of a chelated vanadocene

Bis(cyclopentadienyl) complexes of vanadium (IV) or vanadocenes are rapid and potent inhibitors of human sperm motility with potential as a new class of contraceptive agents. This study sought to determine the vaginal contraceptive activity of vanadocene dithiocarbamate (VDDTC), a stable vanadocene (IV)-chelated complex, using the standard rabbit model as well as the domestic pig as a physiologically relevant animal model for contraception. In experiment I, ovulating New Zealand White does in subgroups of eight were artificially inseminated (AI) with semen mixed with VDDTC (0.01–1 mM) or vehicle. In experiment II, ovulating does in subgroups of 18 were AI at 5 and 60 min after intravaginal application of a gel with and without 0.1% VDDTC or 2% nonoxynol-9 (N-9) (Gynol II, Ortho Pharmaceutical, Raritan, NJ), and allowed to complete term pregnancy. In experiment III, seven sexually mature Duroc gilts in standing estrus were AI with and without intravaginal application of 0.1% VDDTC gel microemulsion. Exposure of rabbit semen to VDDTC at the time of artificial insemination resulted in a dose-dependent reduction in fertility. Exposure of semen to 1 mM VDDTC led to complete inhibition of fertility as assessed by the number of embryos (control 49/94 vs. VDDTC-treated 0/117, p<.0001) or the percent embryos (52% vs. 0%, respectively) based on number of embryos to corpora lutea. Intravaginal administration of 0.1% VDDTC gel microemulsion or Gynol II prior to artificial insemination significantly inhibited term pregnancy rates (88% and 62% inhibition, respectively) when compared to control gel alone. Vanadocene dithiocarbamate gel microemulsion provided 80% inhibition of fertility even when insemination was delayed until 60 min after intravaginal application of VDDTC gel microemulsion. Rabbits that delivered litters despite intravaginal exposure of semen to VDDTC via gel microemulsion had healthy offsprings with no apparent perinatal repercussions. In domestic pigs, intravaginal applications of 0.1% VDDTC gel microemulsion prior to artificial insemination led to complete inhibition of fertility as assessed by the number of embryos (control 29/52 vs. VDDTC-treated 0/44, p<.0001) or the percent embryos (56% vs. 0%, respectively) based on the number of embryos to corpora lutea. These results suggest that VDDTC is a potent contraceptive agent in vivo. Intravaginal use of VDDTC via a gel microemulsion has clinical potential as a safe alternative to currently used detergent-type contraceptives.

Productive performance of the single farrowing system for pigs

This paper reports two experiments, the aims of which were to contribute to the development of the single farrowing production system for pigs. The first reports the induction of oestrus in three groups of 70 Duroc gilts (167 days old, body weight 93.6 kg) via the injection of either 1000, 600 or 400 IU of pregnant mare serum gonadotrophin (PMSG) plus 500, 200 or again 200 IU of human chorionic gonadotrophin (hCG) respectively. No significant differences were observed among these treatments with respect to the percentage of gilts entering oestrus, their fertility or their prolificacy. The average number of piglets weaned per farrowed gilt was 5.61, 5.66 and 6.69 (P

검정종료돈의 체중변화에 따른 일당중체량, 등지방두께 및 정육율의 반복력과 상관

Repeatabilities and Correlations among Average Daily Gain, Backfat Thickness and Lean Percent in Swine The repeatability, correlation and rank correlation coefficients among average daily gain, backfat thickness and lean percent were estimated on the basis of records tested from August 1999 to February 2000 with 695 pigs of Duroc, Landrace and Yorkshire boars and gilts tested at 2nd Korea Swine Test Station located in Ha-dong, Kyeongnam Province. The effect of the sex, breed and month of measured were estimated by the least square method. The repeatabilities were estimated from the component of variance among repeated measurements of the trait for the same animal. The results obtained are summarized as follow ; 1. The means of the major economic traits studied were 142.1 days, 173.7 days and 182.5 days for age at 1st, 2nd and 3rd measure, 57.9%, 56.2% and 55.2% for lean percent at 1st, 2nd and 3rd measure, 1.33cm, 1.61cm and 1.63cm for backfat thickness at 1st, 2nd and 3rd measure, 946.6g, 879.2g and 879.4g for average daily gain at 1st, 2nd and 3rd measure, respectively. 2. The correlation coefficients between the backfat thicknesses measured at 1st and 2nd, at 2nd and 3rd, at 1st and 3rd were 0.424, 0.700 and 1.424, respectively. The correlation coefficients between the lean percent measured at 1st and 2nd, at 2nd and 3rd, at 1st and 3rd were 0.493, 0.619 and 0.471, respectively. The correlation coefficients between the average daily gain measured at 1st and 2nd, at 2nd and 3rd, at 1st and 3rd were 0.716, 0.861 and 0.601, respectively. 3. The rank correlation coefficients between backfat thickness measured at 1st and 2nd, at 2nd and 3rd, at 1st and 3rd were 0.438, 0.693 and 0.441, respectively. The rank correlation coefficients between lean percent measured at 1st and 2nd, at 2nd and 3rd, at 1st and 3rd were 0.508, 0.593 and 0.478, respectively. The rank correlation coefficients between average daily gain measured at 1st and 2nd, at 2nd and 3rd, at 1st and 3rd were 0.704, 0.834 and 0.571, respectively. 4. The estimated repeatabilities of the traits studied were 0.428 for the lean percent, 0.374 for the backfat thickness and 0.673 for the average daily gain, respectively.

Litter size and vagina-cervix catheter penetration length in gilts.

As in other species, the reproductive tract in pigs increases in size with age and body weight, and the development of the reproductive tract depends on a balance between development of the pituitary-ovarian axis and the influence of metabolic hormones. Two experiments were conducted in prepubertal Duroc gilts, 150-180 days of age, to determine whether litter size is related to vaginal-cervix catheter penetration length during insemination. In experiment 1, oestrus was induced in 452 gilts with a combined dose of 400 IU Pregnant Mare Serum Gonadotrophine (PMSG) + 200 IU human chorionic gonadotropin (hCG). The gilts were classified into three catheter penetration length groups: Ih, < or = 21 cm; IIh, > 21 and < 28 cm, IIIh, > 28 cm. The litter size was lowest in group Ih (7.35 +/- 0.15) compared with groups IIh (7.81 +/- 0.12; p < 0.05) and IIIh (10.0 +/- 0.36; p < 0.001). In experiment 2, first oestrus was induced in 162 gilts by boar exposure. The gilts were classified into three catheter penetration length groups at insemination during their second oestrus: In, < or = 24 cm; IIn, > 24 and < 26 cm; IIIn, > 26 cm. As in experiment 1, the litter size was lowest in the group with the shortest catheter penetration length (8.32 +/- 0.19). The litter size was not different among gilts of groups IIn and IIIn (8.84 +/- 0.35 and 9.56 +/- 0.46, respectively), but litter size was lower (p < 0.05) in group In than in group IIn. Based on the combined data from both experiments, the correlation between the catheter penetration length and total number of piglets born was expressed as: y =5.346 +/- 0.104x; r = 0.361 (p < 0.05). Fertility rate was not different among the groups of gilts induced into oestrus by hormone treatment or inseminated in the second oestrus; however, the total fertility rate of boar-exposed gilts was higher (p < 0.0001) than PMSG/hCG treated animals. Thus, it is possible to conclude that litter size at first farrowing is associated with vaginal-cervix catheter penetration length during insemination of the gilt.

Reproduction of 3/4 White Composite and 1/4 Duroc, 1/4 Meishan, 1/4 Fengjing, or 1/4 Minzhu gilts and sows.

Females were either 1/4 Duroc, 1/4 Meishan, 1/4 Fengjing, or 1/4 Minzhu, and the remainder were 3/4 White Composite. A greater percentage of Fengjing crosses reached puberty than Duroc or Minzhu (P < .05), and Meishan crosses were intermediate and not different (P > .05) from other breed types. After adjusting for differences in percentage detected owing to termination of observation for estrus, breed types ranked Fengjing, Meishan, Minzhu, and Duroc from youngest to oldest at puberty with approximately 14 d between adjacent breed types. Meishan and Fengjing crosses had a greater (P < .05) ovulation rate than Minzhu or Duroc crosses. With the exception of number of fetuses at 100 d and average fetal weight at 60 d, differences among breed types were not detected (P > .05) for litter or uterine traits measured on gilts slaughtered at 60 or 100 d of gestation. Total number of pigs born was greater (P < .05) for 1/4 Fengjing than for 1/4 Duroc gilts. Gestation length, number born alive, number weaned, litter birth weight, or litter weaning weight for gilts did not differ (P > .05) among breed types. Duroc crosses were heavier (P < .01) than Chinese crosses at d 1 and 28 after farrowing, but breed types did not differ (P > .05) for backfat thickness at those times. Breed types did not differ (P > .05) for the ratio of litter gain from 0 to 28 d/total Mcal or any of the component traits in the ratio. Postweaning estrus activity, conception rate, and litter and uterine traits of sows bred for second parity were not affected (P > .05) by breed type. These analyses indicate that crossbred gilts containing 1/4 Meishan, 1/4 Fengjing, or 1/4 Minzhu will reach puberty earlier, have larger litters, and weigh less at first parity than gilts containing 1/4 Duroc, but they do not have any significant advantage in litter size at second parity.

Reproduction of F1 Meishan, Fengjing, Minzhu, and Duroc gilts and sows.

Gilts were the progeny of eight Duroc, nine Meishan, eight Fengjing, and seven Minzhu boars mated to composite (1/4 Chester White, 1/4 Landrace, 1/4 Large White, and 1/4 Yorkshire) females. Age at puberty was youngest (P < .05) for Meishan and Fengjing crosses followed by Minzhu crosses and then Duroc crosses. Fengjing crosses had a higher (P < .05) ovulation rate than Meishan or Minzhu crosses, which had a higher (P < .05) ovulation rate than Duroc crosses. Meishan and Fengjing crosses had larger (P < .05) litters than Duroc crosses at 60 and 100 d of gestation, at birth, and at weaning. Minzhu crosses also had larger (P < .05) litters than Duroc crosses at all stages but were significantly lower than Meishan and Fengjing crosses only for litter size at 100 d of gestation. Duroc crosses were heavier (P < .05) at farrowing than all three Chinese crosses. Breed groups differed (P < .05) for backfat thickness at weaning but not at farrowing. Duroc crosses were the least efficient (P < .05) in converting feed energy into litter gain from birth to weaning; Fengjing crosses were less efficient (P < .05) than Minzhu crosses but neither differed significantly from the intermediate value of the Meishan crosses. Chinese crosses returned to estrus sooner after weaning (P < .05) than Duroc crosses. Ovulation rate at second parity was highest for Fengjing crosses followed by Meishan, Duroc, and Minzhu crosses; difference among nonadjacent means were significant (P < .05). Differences among crosses were not large or significant for number of fetuses at 100 d of gestation at second parity. Results indicate Meishan and Fengjing can be used to produce crossbred gilts that have a higher level of reproductive performance than Duroc crossbred gilts; the reproductive performance of Minzhu crosses would be intermediate. However, the Chinese crosses would not be expected to have an advantage in litter size at second parity.

Flow cytometric evaluation of boar semen by the sperm chromatin structure assay as related to cryopreservation and fertility

Boar semen from a heterospermic mating trial and semen cryopreserved by various methods were evaluated by the flow cytometric sperm chromatin structure assay (SCSA), which measures the susceptibility of sperm nuclear DNA to acid-induced denaturation in situ. Spermatozoa were treated with a pH 1.4 buffer and then stained with the metachromatic dye acridine orange. Acridine orange intercalated into double-stranded DNA (native) fluoresces green while single-stranded DNA (denatured) fluoresces red when excited with 488 nm light. The ratio of red to total fluorescence provides an index of normality/abnormality. The SCSA data on neat boar semen or semen in either Kiev-Merck or Pursel-Johnson extender and frozen directly on dry ice blocks or plunged into LN 2 did not differ within individual boars. Therefore, chromatin structure, as measured by the SCSA, was not influenced differently by these 2 methods of semen cryopreservation. When semen from 6 boars was mixed in equal sperm numbers in six 3-way combinations and inseminated into at least 3 Duroc gilts per combination, 4 of the 6 combinations yielded 2 litters, while the remaining 2 combinations yielded 3 litters. The SCSA correctly predicted both the high and low fertility boars based on a ratio of offspring as deviated from the theoretical percentage. Thus, the SCSA was found to be a valuable adjunct method for evaluating boar cemen quality.