149 The second isoform of gonadotrophin-releasing hormone and its receptor affect boar semen quality

Pigs are the only livestock species encoding a functional protein for both the second isoform of gonadotrophin-releasing hormone (GnRH-II) and its cognate receptor (GnRHR-II). Unlike the classical GnRH system (GnRH-I and GnRHR-I), GnRH-II and GnRHR-II are abundantly produced in porcine testes. Moreover, GnRH-II binding its receptor on Leydig cells stimulates luteinizing hormone-independent testosterone secretion. Interestingly, GnRHR-II is also localised to the connecting piece of mature, ejaculated spermatozoa, whereas GnRH-II is detected in seminal plasma, an interaction possibly influencing the function of sperm. To examine the role of GnRH-II and its receptor in the testis, we produced a swine line with reduced endogenous GnRHR-II levels (GnRHR-II KD). The objectives of this study were to (1) compare sperm characteristics between mature GnRHR-II KD and littermate control boars on the day of collection and following semen extension and (2) determine whether a GnRHR-I and GnRHR-II antagonist alters sperm characteristics after storage of extended semen. In Experiment 1, GnRHR-II KD (n=3) and littermate control (n=3) ejaculates were collected (Day 1) and computer-assisted sperm analysis (CASA) was performed (IVOS II Animal; Hamilton Thorne) to determine measures of sperm motion (motility, progressive motility, slow, and static), morphology (normal morphology, bent tail, coiled tail, distal droplet, proximal droplet (PD), distal midpiece reflex, elongation, and area), and kinematics (length of average path (DAP), length of straight line path (DSL), length of curvilinear path (DCL), average path velocity (VAP), straight line velocity (VSL), curvilinear velocity (VCL), straightness (STR), linearity (LIN), amplitude of lateral head displacement (ALH), beat-cross frequency, and wobble (WOB)). Next, 3 billion sperm were extended with Androstar Plus (80-mL doses; Minitube) and stored at 17°C until Day 7 CASA. Data were analysed with the MIXED procedure of SAS (SAS Institute Inc.). On Day 1, semen doses from GnRHR-II KD boars had reduced DSL, VSL, STR, LIN, and WOB (P<0.05), whereas sperm from control boars possessed more PD (P<0.01). Day 7 CASA revealed that transgenic sperm had reduced DAP, DCL, VAP, and VCL, although sperm from control boars were slower (P<0.05). In Experiment 2, control ejaculates (n=3) were extended as above, treated with increasing concentrations (0, 0.0001, 0.001, 0.01, 0.1, 1, and 10μM) of a GnRH antagonist inhibiting both GnRHR-I and GnRHR-II (SB-75, cetrorelix), and stored at 17°C until Day 7 and 9 CASA. On Day 7, only sperm characteristics in doses treated with 10μM SB-75 were significantly lower (normal morphology, DAP, DCL, VAP, VCL, and ALH) or higher (PD, WOB, and area) than controls. Similar differences (except ALH; P<0.10) for the 10μM SB-75 treatment were detected on Day 9; however, motility, slow, static, STR, and LIN were also reduced (P<0.05). Thus, these data suggest that GnRH-II and its receptor are important to sperm function, representing a potential avenue to improve semen preservation. This research was funded by USDA/NIFA AFRI (2017-67015-26508; BRW).

First Limit on the Direct Detection of Lightly Ionizing Particles for Electric Charge as Low as e/1000 with the Majorana Demonstrator

The Majorana Demonstrator is an ultralow-background experiment searching for neutrinoless double-beta decay in ^{76}Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. Free, relativistic, lightly ionizing particles with an electrical charge less than e are forbidden by the standard model but predicted by some of its extensions. If such particles exist, they might be detected in the Majorana Demonstrator by searching for multiple-detector events with individual-detector energy depositions down to 1 keV. This search is background-free, and no candidate events have been found in 285 days of data taking. New direct-detection limits are set for the flux of lightly ionizing particles for charges as low as e/1000.

Search for Neutrinoless Double-β Decay in ^{76}Ge with the Majorana Demonstrator

The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in ^{76}Ge. The Majorana Demonstrator comprises 44.1 kg of Ge detectors (29.7 kg enriched in ^{76}Ge) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. Here we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5 keV FWHM at Q_{ββ} and a very low background with no observed candidate events in 9.95 kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of 1.9×10^{25}  yr (90% C.L.). This result constrains the effective Majorana neutrino mass to below 240-520 meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is 4.0_{-2.5}^{+3.1}  counts/(FWHM t yr).

Production of a gonadotropin-releasing hormone 2 receptor knockdown (GNRHR2 KD) swine line

Swine are the only livestock species that produce both the second mammalian isoform of gonadotropin-releasing hormone (GNRH2) and its receptor (GNRHR2). Previously, we reported that GNRH2 and GNRHR2 mediate LH-independent testosterone secretion from porcine testes. To further explore this ligand-receptor complex, a pig model with reduced GNRHR2 expression was developed. Small hairpin RNA sequences targeting porcine GNRHR2 were subcloned into a lentiviral-based vector, lentiviral particles were generated and microinjected into the perivitelline space of zygotes, and embryos were transferred into a recipient. One GNRHR2 knockdown (KD) female was born that subsequently produced 80 piglets from 6 litters with 46 hemizygous progeny (57% transgenic). Hemizygous GNRHR2 KD (n = 10) and littermate control (n = 7) males were monitored at 40, 100, 150, 190, 225 and 300 days of age; body weight and testis size were measured and serum was isolated and assayed for testosterone and luteinizing hormone (LH) concentrations. Body weight of GNRHR2 KD boars was not different from littermate controls (P = 0.14), but testes were smaller (P < 0.05; 331.8 vs. 374.8 cm³, respectively). Testosterone concentrations tended (P = 0.06) to be reduced in GNRHR2 KD (1.6 ng/ml) compared to littermate control (4.2 ng/ml) males, but LH levels were similar (P = 0.47). The abundance of GNRHR2 mRNA was reduced (P < 0.001) by 69% in testicular tissue from mature GNRHR2 KD (n = 5) versus littermate control (n = 4) animals. These swine represent the first genetically-engineered model to elucidate the function of GNRH2 and its receptor in mammals.

New Limits on Bosonic Dark Matter, Solar Axions, Pauli Exclusion Principle Violation, and Electron Decay from the Majorana Demonstrator

We present new limits on exotic keV-scale physics based on 478 kg d of Majorana Demonstrator commissioning data. Constraints at the 90% confidence level are derived on bosonic dark matter (DM) and solar axion couplings, Pauli exclusion principle violating (PEPV) decay, and electron decay using monoenergetic peak signal limits above our background. Our most stringent DM constraints are set for 11.8 keV mass particles, limiting g_{Ae}<4.5×10^{-13} for pseudoscalars and (α^{'}/α)<9.7×10^{-28} for vectors. We also report a 14.4 keV solar axion coupling limit of g_{AN}^{eff}×g_{Ae}<3.8×10^{-17}, a 1/2β^{2}<8.5×10^{-48} limit on the strength of PEPV electron transitions, and a lower limit on the electron lifetime of τ_{e}>1.2×10^{24}  yr for e^{-}→ invisible.

5 TESTICULAR GnRH-II RECEPTOR KNOCKDOWN IMPAIRS DIURNAL TESTOSTERONE SECRETION IN THE BOAR

The second mammalian GnRH isoform (GnRH-II) and its specific receptor (GnRHR-II) are ubiquitously expressed, with elevated levels in the testis. Gene coding errors prevent their production in many species, but both genes are functional in swine. We demonstrated that GnRHR-II localizes to porcine Leydig cells, and exogenous GnRH-II robustly stimulates testosterone production in vivo, despite minimal luteinizing hormone (LH) secretion. These data suggest that GnRH-II directly effects steroidogenesis in the boar testis. To explore this hypothesis, we produced a GnRHR-II knockdown (KD) swine line. Upon characterisation of this line, serum testosterone concentrations were reduced in GnRHR-II KD compared with littermate control males during pubertal development. However, concentrations of LH were unaffected, indicating that GnRHR-II KD impairs steroidogenesis directly at the testis rather than inhibiting gonadotropin secretion from the anterior pituitary gland. Based on these results, the objective of this study was to compare diurnal secretory patterns of testosterone in mature GnRHR-II KD (n = 5) and littermate control (n = 5) males. Boars were fit with indwelling jugular cannulae and blood was collected every 15 min for 8 h. Serum was assayed for testosterone concentration via radioimmunoassay. Next, GnRHR-II KD (n = 5) and littermate control (n = 4) boars were killed, testis weight was recorded, and testicular tissue was collected for RNA isolation. To confirm KD in these animals, digital droplet PCR was performed to quantify GnRHR-II mRNA abundance (normalized to β-actin). Data were analysed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC, USA) with line (transgenic or control) as the fixed effect and litter as a random effect. For hormone data, time and line × time interaction were included as fixed effects, with time as a repeated measure. Although there was no effect of time or line × time interaction (P > 0.05) on serum testosterone concentrations, we observed a line effect (P < 0.05). Differences between lines were dramatic; testosterone was reduced by 82% in GnRHR-II KD (0.75 ± 0.05 ng mL−1) compared with littermate control (4.09 ± 0.29 ng mL−1; P < 0.05) males. Despite divergent testosterone levels, testis weights were similar between lines (P > 0.05) indicative of altered Leydig cell function as opposed to hypertrophy/hyperplasia. Given that testicular GnRHR-II mRNA levels were reduced by 69% in transgenic animals (P < 0.001), these data demonstrate that GnRH-II and its receptor play a critical role in testosterone biosynthesis within porcine Leydig cells. Thus, this report reveals novel mediators of testicular function in the boar and challenges the central dogma of testosterone regulation. Because testosterone dictates male reproductive success, GnRH-II and its receptor represent unique targets to improve fertility in swine. This study was partially supported by NIFA Hatch (NEB-26-199; BRW) and AFRI (2011-67015; CAL) funds.

217 PRODUCTION OF A GONADOTROPIN-RELEASING HORMONE II RECEPTOR KNOCKDOWN SWINE LINE

Unlike the native form of gonadotropin-releasing hormone (GnRH-I), the second isoform of GnRH (GnRH-II) is highly conserved throughout evolution and is ubiquitously expressed. The pig represents one of the few species possessing coding sequence for a functional receptor specific to GnRH-II (GnRHR-II). Binding of GnRH-II to its receptor has been linked to regulation of cell proliferation, feed intake, and the interaction between energy balance and reproductive behaviour. The objective of this study was to develop a porcine model with reduced levels of endogenous GnRHR-II to examine the biological role of this G-protein coupled receptor. Previously, we produced lentiviral particles from a vector overexpressing both small hairpin RNA (shRNA) sequence specific to the porcine GnRHR-II and cDNA encoding the fluorescent ZsGreen1 protein (pLVX-shRNA2; Clontech). Transduction of swine testis cells with these particles (1.44 × 107 viral particles) reduced porcine GnRHR-II mRNA levels by 99% compared with control particles (P < 0.05). In the current study, pronuclear zygotes (n = 50) surgically collected from 1 white crossbred donor sow were microinjected into the perivitelline space with lentiviral particles containing the shRNA2 sequence (3.3 × 108 IU mL–1) using a Nikon diaphot inverted microscrope equipped with Eppendorf micromanipulators and FemtoJet injection system. A total of 40 microinjected zygotes were immediately transferred into the oviduct of 1 synchronized recipient female, resulting in the production of 5 healthy, live piglets (20% efficiency rate). Interestingly, 1 female exhibited green fluorescence, indicative of successful transgene integration and expression. Transgene integration was confirmed via conventional PCR using primers designed to amplify portions of the human U6 promoter driving the shRNA, the CMV promoter driving ZsGreen1 expression, and the multiple cloning site for incorporation of the shRNA sequence. Next, inverse PCR was performed to determine the location and number of integration sites. Sequencing analysis of PCR products revealed that a single integration site was present on chromosome 14, aligning with clone NW_003612067.1 with 99% identity and matching identities 448,946–448,37. The GnRHR-II knockdown (KD) female along with 2 female littermates were maintained and monitored during development. Attainment of puberty occurred at 149 days for the transgenic female and 145 and 151 days for littermate control gilts (P > 0.05). Upon exhibition of their third behavioural oestrus, females were bred and allowed to gestate to term. Litter size was similar between the GnRHR-II KD female (15 live piglets) and control littermates (15 and 16 live piglets). Of the 15 piglets produced, 5 (3 males and 2 females) were positive for green fluorescence, confirming germline transmission of the transgene and further evidence for a single integration site. The swine produced from this study represent the first animal model to examine the physiological implications of reduced GnRH-II receptor levels.

6 PRODUCTION OF GONADOTROPIN-RELEASING HORMONE II RECEPTOR KNOCKDOWN SWINE

The second mammalian isoform of GnRH (GnRH-II) is highly conserved from bony fish to humans. However, coding sequence for the receptor specific to this ligand contains reading errors in many species, suggesting the inability to produce a functional receptor. In contrast, the porcine GnRH-II receptor gene contains the appropriate sequence to produce functional protein. The objective of this study was to develop swine with reduced levels of endogenous GnRH-II receptors. Two potential target small hairpin RNA (shRNA1 and shRNA2) sequences specific to the porcine GnRH-II receptor were identified and subcloned into the lentiviral-based, pLVX-shRNA2 vector (Clontech) that provides both shRNA and fluorescent ZsGreen1 coexpression. Lentiviral particles were produced from each shRNA vector as well as a control vector using the Lenti-X HTX Packaging System (Clontech). The ability of shRNA1 and shRNA2 lentiviral particles to reduce porcine GnRH-II receptor mRNA levels was tested in a swine testis-derived (ST) cell line. The day before transduction, ST cells (2 × 106) were plated in 100-mm plates containing high-glucose DMEM supplemented with 10% FBS, 2 mM glutamine, 100 U mL–1 of penicillin and 100 mg mL–1 of streptomycin sulfate. Next, cells were transduced with 1.44 × 107 viral particles per plate for 48 h. The cells were harvested, RNA was extracted and converted to cDNA and quantitative PCR was performed to determine relative levels of GnRH-II receptor mRNA. Values were normalized using the expression levels of 18s rRNA and compared with GnRH-II receptor mRNA levels in ST cells transduced with control lentiviral particles. Lentiviral particles containing either shRNA1 or shRNA2 sequences significantly reduced GnRH-II receptor mRNA levels (95 and 99%, respectively) compared with control particles (P < 0.05). Next, lentiviral particles containing the shRNA2 sequence (1.15 × 109 infectious units mL–1) were microinjected within the perivitelline space of in vivo-derived pronuclear zygotes (n = 15) using a Nikon diaphot inverted microscrope equipped with Eppendorf micromanipulators and an Eppendorf FemtoJet injection system. Microinjected zygotes were subsequently cultured in 50-μL drops of NCSU-23 under mineral oil in a humidified 5% CO2 in air environment. Following 120 h of culture, 93% of the zygotes developed to the compact morula stage, whereas 73% formed blastocysts at 168 h. By 192 h, 80% of the microinjected embryos developed to the blastocyst or expanded blastocyst stages. Fluorescent microscopy revealed that all blastocysts expressed ZsGreen1, indicating a 100% transduction efficiency of shRNA2 lentiviral particles. Finally, embryos were surgically collected from white crossbred donor sows and transduced as described above. A total of 40, 33 and 23 microinjected zygotes were immediately transferred into 3 synchronized recipient females that will be allowed to gestate to term. The animals produced from this study will represent the first animal model to examine the physiological implications of reduced GnRH-II receptor levels.

Homologous regulation of the gonadotropin-releasing hormone receptor gene is partially mediated by protein kinase C activation of an activator protein-1 element

Homologous regulation of GnRH receptor (GnRHR) gene expression is an established mechanism for controlling the sensitivity of gonadotropes to GnRH. We have found that expression of the GnRHR gene in the gonadotrope-derived alpha T3-1 cell line is mediated by a tripartite enhancer that includes a consensus activator protein-1 (AP-1) element, a binding site for SF-1 (steroidogenic factor-1), and an element we have termed GRAS (GnRHR-activating sequence). Further, in transgenic mice, approximately 1900 b.p. of the murine GnRHR gene promoter are sufficient for tissue-specific expression and GnRH responsiveness. The present studies were designed to further delineate the molecular mechanisms underlying GnRH regulation of GnRHR gene expression. Vectors containing 600 bp of the murine GnRHR gene promoter linked to luciferase (LUC) were transiently transfected into alpha T3-1 cells and exposed to treatments for 4 or 6 h. A GnRH-induced, dose-dependent increase in LUC expression of the -600 promoter was observed with maximal induction of LUC noted at 100 nM GnRH. We next tested the ability of GnRH to stimulate expression of vectors containing mutations in each of the components of the tripartite enhancer. GnRH responsiveness was lost in vectors containing mutations in AP-1. Gel mobility shift data revealed binding of fos/jun family members to the AP-1 element of the murine GnRHR promoter. Treatment with GnRH or phorbol-12-myristate-13-acetate (PMA) (100 nM), but not forskolin (10 microM), increased LUC expression, which was blocked by the protein kinase C (PKC) inhibitor, GF109203X (100 nM), and PKC down-regulation (10 nM PMA for 20 h). In addition, a specific MEK1/MEK2 inhibitor, PD98059 (60 microM), reduced the GnRH and PMA responses whereas the L-type voltage-gated calcium channel agonist, +/- BayK 8644 (5 microM), and antagonist, nimodipine (250 nM), had no effect on GnRH responsiveness. Furthermore, treatment of alpha T3-1 cells with 100 nM GnRH stimulated phosphorylation of both p42 and p44 forms of extracellular signal-regulated kinase (ERK), which was completely blocked with 60 microM PD98059. We suggest that GnRH regulation of the GnRHR gene is partially mediated by an ERK-dependent activation of a canonical AP-1 site located in the proximal promoter of the GnRHR gene.

Production of bovine alpha-lactalbumin in the milk of transgenic pigs

High production of milk and its components are necessary to allow maximal growth of developing pigs. In this study, transgenic pigs were produced containing the alpha-lactalbumin gene, whose product is a potential limiting component in the production of milk. Two lines of transgenic pigs were produced to analyze the effects that overproduction of the milk protein alpha-lactalbumin may have on milk production and piglet growth. Transgenic pigs were produced through microinjection of the bovine alpha-lactalbumin gene. The gene construct contained 2.0 kb of 5' flanking region, the 2.0 kb coding region, and 329 bp of 3' flanking region. Sows hemizygous for the transgene produced as much as .9 g of bovine alpha-lactalbumin per liter of pig milk. The production of the bovine protein caused approximately a 50% increase in the total alpha-lactalbumin concentration of pig milk throughout a lactation. The concentration of bovine alpha-lactalbumin was highest on d 0 and 5 of lactation and decreased as lactation progressed. The ratio of bovine to porcine alpha-lactalbumin changed during the sow's lactation. This ratio was 4.3 to 1 on d 0 of lactation, but by d 20 of lactation the ratio was .43 to 1. This suggested that the bovine transgene and the endogenous porcine gene are under slightly different control mechanisms. The higher level of total alpha-lactalbumin present on d 0 of lactation was correlated with higher lactose percentage on d 0 in transgenic sows (3.8%), compared with controls (2.6%) (P < .01). Although there was also a trend for higher lactose percentage in transgenic sows on d 5 and 10 of lactation, no significant differences were observed. These data suggest that alpha-lactalbumin is limiting early in lactation of swine. Furthermore, higher concentrations of alpha-lactalbumin early in lactation may boost milk output.

Growth and body composition of Meishan and Yorkshire barrows and gilts

Five barrows and five gilts of each of two breeds (Meishan [Ms] and Yorkshire [Y]) were slaughtered at birth and at 41, 71, 123, and 171 d of age and five gilts of each breed were slaughtered at 260 d of age. Major organ and visceral weights were obtained immediately postmortem (PM), whereas carcass characteristics, carcass composition, femur measurements, and two individual muscle weights were obtained 24 h PM. Linear and quadratic regression coefficients on age differed between the two breeds, in favor of Y barrows and gilts, for live weight, carcass weight, longissimus muscle area (LMA), liver, heart, spleen, and kidney weights, and femur cross-sectional, medullary, and cortical areas (P < .001), leaf fat weight, and percentage of body fat and protein. In contrast to somatic tissue, Ms gilts had uteri and ovaries that grew faster than those of Y gilts from birth to 260 d of age (P < .05), although the uterus and ovary weights were similar for both breeds by 260 d of age (P < .05). Regression coefficients differed (P < .05) between the two sexes for live, carcass, liver, lung and trachea, stomach and esophagus and leaf fat weights, dressing percentage, percentage of body protein, 10th rib backfat (TRBF) thickness (P < .001), and small intestine, kidney (P < .01), heart, and spleen weights (P < .05). Breed differences in regression coefficients differed between the two sexes for percentage of body protein and leaf fat weights (P < .05). Yorkshire pigs were larger, later-maturing pigs that grew faster from birth to 171 d of age. Yorkshire pigs slaughtered at 171 d of age had heavier total wholesale cut (WC), trimmed cut (TC), and boneless cut (BC) weights than did Ms pigs of the same age (P < .001).

Comparison of the semen characteristics of Fengjing, Meishan and Yorkshire boars

Semen characteristics of Chinese Fengjing, CHinese Meishan and American Yorkshire boars were examined. Samples were collected from 24 boars: 6 Fengjing, 12 Meishan and 6 Yorkshire. Three semen characteristics and 6 biochemical evaluations of semen or seminal plasma were analyzed. The whole semen parameters measured were gelatinous (gel) and gel-free volume and progressive motility. Fengjing boars were higher in gel volume than Meishan (P < 0.05) but not Yorkshire boars (P > 0.25), while Yorkshire boars were higher than Meishan boars in gel volume (P < 0.10). The gel-free volume was higher in Yorkshire and Fengjing boars than Meishan boars (P < 0.10), but Fengjing gel-free volumes did not differ from Yorkshire gel-free volumes (P > 0.80). However, the only difference detected for progressive motility was between Fengjing and Meishan boars (78.5 vs 74.5%; P < 0.10). Sperm concentration was higher in Meishan than Yorkshire boars (P < 0.01) although these breeds did not differ from Fengjing boars (P > 0.18). The biochemical messurements made were fructose, galactose, inositol, total carbohydrate and total protein in seminal plasma and pH in gel-free semen. Fengjing boars had higher concentrations of galactose in seminal plasma than Meishan or Yorkshire boars (P < 0.05), while Meishan seminal plasma had higher galactose concentrations than Yorkshire seminal plasma (P < 0.10). Fructose, inositol and total carbohydrate concentrations were all higher in Fengjing and Meishan seminal plasma than Yorkshire seminal plasma (P < 0.05). Fengjing seminal plasma had higher levels of inositol than Meishan seminal plasma (769 vs 566 mg/100 ml; P < 0.10). Furthermore, Fengjing and Meishan semen had similar fructose and total carbohydrate concentrations (P > 0.80). The pH level and total protein concentration did not differ among the 3 breeds (P > 0.30). This study indicated that breed differences were detected for several seminal parameters, although no single breed had consistantly higher values for all the parameters measured.

Effects of porcine somatotropin on growth and carcass composition of Meishan and Yorkshire barrows

Effects of porcine somatotropin (pST) on growth and carcass characteristics of Meishan (Ms) and Yorkshire (Y) barrows given 3 mg of pST or saline daily were determined for two end points. First, 26 Ms and 26 Y barrows were treated from 119 d of age until the Y barrows reached 108 kg. Second, another 18 Ms barrows were treated to 108 kg BW. Age- and weight-matched treatments were analyzed. Results for both groups indicated pST effects (P < .05) for feed conversion (+) and intake (-), dressing percentage (-), percentage of carcass fat (-) and protein and water (+), leaf fat (-), backfat (BF) thickness (-), longissimus muscle area (LMA; +), skin thickness (+), muscle firmness and marbling scores (-), organ weights (+), belly (-), clear plate (-), ham (+), and total boneless cuts (BC; +). Somatotropin effects were also present for loin (-) and boneless Boston butt (BBB; +) in the age-matched group and for ADG (+), carcass weight (-), loin (-), jowl (-), and tenderloin (+) in the weight-matched group. Breed effects (P < .05), in favor of Y barrows, in both treatments existed for ADG (+) and feed intake (+), carcass weight (+), dressing percentage (+), LMA (+), skin thickness (-), muscle color and firmness scores (-), muscling score (+), all wholesale cuts (WC; +) except clear plate (age-matched), all trimmed cuts (TC; +) except picnic shoulder (weight-matched), and all BC (+). Breed effects, in favor of Y barrows, were also determined for carcass length (+), percentage of carcass ash (-), leaf fat (+), average BF thickness (+), and heart (-) and liver (-) weights in age-matched animals and percentage of carcass fat (-), protein (+), water (+), leaf fat (-), 10th rib, average, and P2 BF thicknesses (-), marbling score (-), femur length (-), and liver weights (+) in weight-matched animals. A higher response to pST (P < .05) was determined in Ms barrows than in Y barrows for percentage of carcass protein (+), liver (+), and heart (+) in the age-matched treatment and 10th rib BF thickness (-) and heart weight (+) in the weight-matched treatment. Yorkshire barrows treated with pST had more improved values for color score (+; age-matched) and BBB (+; weight-matched).

Age at puberty, ovulation rate, uterine length, prenatal survival and litter size in Chinese Meishan and Yorkshire females

Studies on the ovulation rate, prenatal survival and litter size of Chinese Meishan pigs have given widely divergent results depending on the extent of inbreeding of the animals, their original genetic diversity, the age and parity, and the conditions of management. To obtain meaningful results, it is necessary to characterize the population under study. The following report characterizes populations of Meishan and Yorkshire of a widely diverse background. First farrowing data were collected on 21 Meishan and 20 Yorkshire gilts. Meishan gilts had 12.4 fully formed piglets and Yorkshire gilts had 7.4 fully formed piglets (P < 0.01). Meishan gilts averaged 1.86 mummified fetuses per litter vs 0.05 per Yorkshire litter (P < 0.01). Yorkshire piglets averaged 1.3 kg body weight at birth vs 0.9 kg for Meishan piglets (P < 0.01). At 47 days of second gestation, 19 Meishan and 12 Yorkshire sows averaged 22.7 and 16.3 corpora lutea (CL), respectively (P < 0.01). Uterine length and number of fetuses were not different (P > 0.40) in the two breeds. Daily estrous detection of 50 Meishan and 34 Yorkshire gilts began at 60 and 120 days of age, respectively. Meishan gilts reached sexual maturity at 95 days of age, which was 105 days earlier than Yorkshire gilts (P < 0.01). Meishan gilts were in estrus nearly 1 day longer than Yorkshire gilts at first, second and third estrus (P < 0.05). No differences in cycle length between breeds were detected for the first or second estrous cycle (P > 0.60). Nineteen Meishan gilts were slaughtered at 51 days of gestation and their reproductive tracts were recovered. The mean number of dissected CL (17.0), number of fetuses (13.1), total uterine length (396 cm), spacing per fetus (29.9 cm), allantoic (124.9 ml) and amniotic (32.2 ml) volumes, crown-rump length (82.8 mm), weight (35.4 g), sex, and direction of each fetus were determined. Chinese Meishan gilts reached puberty much earlier and were in estrus longer than Yorkshire gilts and Meishan sows had more CL than Yorkshire sows.