Cervical mucus sialic acid content determines the ability of frozen-thawed ram sperm to migrate through the cervix.

The aim of this study was to investigate the properties and to functionally characterize the cervical mucus that modulates sperm transport through the cervix by using ewe breeds with a divergent pregnancy rate (Belclare and Suffolk; high and low, respectively) following cervical insemination using frozen-thawed semen. Sperm number, as well as sialic acid and fucose content in both the channels and in the lumen of different regions of the cervix were quantified in inseminated Belclare and Suffolk ewes. Expression of glycosyltransferase and MUC genes, glycosidase activity and sialic acid speciation in follicular phase cervical tissue and mucus were assessed. More spermatozoa were found in the cervical channels in the region closest to the cervical os in Belclare than Suffolk ewes (P < 0.05) and Suffolk ewes had a higher sialic acid content in the cervical channels than Belclare ewes (P < 0.05) in all regions of cervix. Suffolk ewes had significantly higher expression of FUT1, ST6GAL1 and MUC5AC than Belclare ewes. There was no difference between the breeds in glycosidase activity (P > 0.05). Levels of Neu5Ac were higher in Belclare than Suffolk ewes (P < 0.05) and levels of Neu5Gc was higher in Suffolk than Belclare ewes (P < 0.05). Competitive sperm penetration assays demonstrated that frozen-thawed sperm progression increased when cervical mucus was incubated with sialyllactose prior to a sperm penetration test (P < 0.05). These results suggest that the difference between Belclare and Suffolk ewes in sperm transport with frozen-thawed semen is due to the higher concentration of sialic acid within channels, which binds to spermatozoa and reduces their ability to traverse the cervix.

An independent validation study of loci associated with nematode resistance in sheep.

Gastrointestinal nematode infection is a constraint on sheep production worldwide. Selective breeding programmes to enhance resistance to nematode infection are currently being implemented in a number of countries. Identification of loci associated with resistance to infection or causative mutations for resistance would enable more effective selection. Loci associated with indicator traits for nematode resistance has been identified in previous studies. In this study, Scottish Blackface, Texel and Suffolk lambs were used to validate the effects at eight genomic regions previously associated with nematode resistance (OAR3, 4, 5, 7, 12, 13, 14, 21). No SNP was significantly associated with nematode resistance at the region-wide level but seven SNPs in three of the regions (OAR4, 12, 14) were nominally associated with trichostrongyle egg count in this study and six of these were also significant when fitted as single SNP effects. Nematodirus egg count was nominally associated with SNPs on OAR3, 4, 7 and 12.

Immunogenomics of gastrointestinal nematode infection in ruminants - breeding for resistance to produce food sustainably and safely.

Gastrointestinal nematode (GIN) infection of ruminants represents a major health and welfare challenge for livestock producers worldwide. The emergence of anthelmintic resistance in important GIN species and the associated animal welfare concerns have stimulated interest in the development of alternative and more sustainable strategies aimed at the effective management of the impact of GINs. These integrative strategies include selective breeding using genetic/genomic tools, grazing management, biological control, nutritional supplementation, vaccination and targeted selective treatment. In this review, the logic of selecting for "resistance" to GIN infection as opposed to "resilience" or "tolerance" is discussed. This is followed by a review of the potential application of immunogenomics to genetic selection for animals that have the capacity to withstand the impact of GIN infection. Advances in relevant genomic technologies are highlighted together with how these tools can be advanced to support the integration of immunogenomic information into ruminant breeding programmes.

A genome-wide association study of bronchodilator response in asthmatics.

Reversibility of airway obstruction in response to ß2-agonists is highly variable among asthmatics, which is partially attributed to genetic factors. In a genome-wide association study of acute bronchodilator response (BDR) to inhaled albuterol, 534 290 single-nucleotide polymorphisms (SNPs) were tested in 403 white trios from the Childhood Asthma Management Program using five statistical models to determine the most robust genetic associations. The primary replication phase included 1397 polymorphisms in three asthma trials (pooled n=764). The second replication phase tested 13 SNPs in three additional asthma populations (n=241, n=215 and n=592). An intergenic SNP on chromosome 10, rs11252394, proximal to several excellent biological candidates, significantly replicated (P=1.98 × 10(-7)) in the primary replication trials. An intronic SNP (rs6988229) in the collagen (COL22A1) locus also provided strong replication signals (P=8.51 × 10(-6)). This study applied a robust approach for testing the genetic basis of BDR and identified novel loci associated with this drug response in asthmatics.

A polymorphism in the thyroid hormone receptor gene is associated with bronchodilator response in asthmatics.

A pro-asthmatic culture milieu and ß2-agonist (isoproterenol) were previously shown to regulate the expression of select transcription factors (TFs) within human airway epithelial and smooth muscle cells. This study tests 1116 single-nucleotide polymorphisms (SNPs) across 98 of these TF genes for association with bronchodilator response (BDR) in asthma patients. Genotyping was conducted using the Illumina HumanHap550v3 Beadchip in 403 non-Hispanic White asthmatic children and their parents. SNPs were evaluated for association with BDR using family and population-based analyses. Forty-two SNPs providing P-values <0.1 in both analyses were then genotyped in three adult asthma trials. One SNP 5' of the thyroid hormone receptor-ß gene was associated with BDR in the childhood population and two adult populations (P-value=0.0012). This investigation identified a novel locus for inter-individual variability in BDR and represents a translation of a cellular drug-response study to potential personalization of clinical asthma management.

Effects of reseeding with perennial ryegrass, chicory or tyfon in pure stands or mixtures on lamb performance postweaning.

Many producers reseed old pasture (OP) with the objective of improving lamb performance. Old pasture was reseeded with perennial ryegrass plus white clover (RGC), RGC plus chicory (CG), RGC plus tyfon (TG), chicory (C), or tyfon (T) to generate five treatments. In addition, a contiguous block of OP was included in the study for comparative purposes. Lambs (n = 286) were assigned to one of the five treatments plus the section of OP from just after weaning until slaughter. Grazing commenced 45 days after the desiccation of OP for reseeding. All lambs were managed by rotational grazing and drafted for slaughter at a specified target BW. No concentrate supplement was offered during the study. For the RGC, CG, TG, C and T treatments and the OP section, the average herbage NDF concentrations were 524, 473, 402, 352, 256 and 565 (SE 15.4) g/kg DM; total grazing days were 5 213, 4 005, 4 466, 2 262, 3 496 and 3 677 (SE 629.3); BW gain to slaughter was 211, 175, 205, 211, 199 and 203 (SE 9.5) g/day; days to slaughter were 91, 100, 84, 86, 78 and 88 (SE 4.8). Compared to RGC, the C, T, CG and TG treatments had lower herbage NDF concentrations (P < 0.05), and there was no difference (P > 0.05) for BW gain or days to slaughter. Chicory yielded significantly fewer (P < 0.05) grazing days, but tended to give a higher (P < 0.06) carcass weight than RGC. It is concluded that neither reseeding OP with RGC, including either C or T with RGC as a multispecies sward, nor growing pure stands of C or T increased (P < 0.05) lamb BW gain from weaning to slaughter or reduced days to slaughter.

Effects of joining at 7 months, and ewe genotype, on the performance of ewes to 19 months of age and that of their progeny to slaughter.

Two ways of reducing the cost of replacements are increasing litter size and number of litters produced; thus, the total weight of lamb carcass output per ewe lifetime. The effects of ewe genotype on the performance of ewes lambing at 1 year and of their progeny to slaughter, and the effect of age at first joining (7 or 19 months) on BW at ~19 months and survival to joining at 19 months were evaluated over two consecutive years, using 460 ewe lambs from three genotypes: Belclare (Bel), Suffolk × Belclare (Suf × Bel) and ≥ 75% Suffolk ancestry (Suf75). Lambs from the three genotypes were at a similar proportion of mature BW and half of the lambs, within genotype, were allocated to be joined for the first time at 7 or 19 months. The ewe lambs were managed in a grass-based rotational-grazing system, except when housed from December to March on a grass silage-based diet. Belclare ewes had larger litters (P < 0.001), reared more lambs per ewe joined (P < 0.01), were lighter at lambing and at 19 months (P < 0.01), were of smaller body size at 19 months (P < 0.001) and their progeny were lighter at weaning (P < 0.05) relative to Suf75 genotype; the Suf × Bel ewes were intermediate for most traits but had a significantly lower litter size (P < 0.05) than Bel ewes. Progeny from Suf × Bel ewes were 17 days younger at slaughter (P < 0.01) relative to those from Bel ewes. Ewe genotype had no effect (P > 0.05) on lamb mortality (born dead, total mortality to weaning), lambing assistance, number of ewes that failed to lamb, or on ewe survival to 19 months of age. Increasing ewe BW at joining increased the probability (P < 0.001) of rearing at least one lamb and this effect was consistent across genotypes. There were significant relationships (P < 0.001) between ewe BW at lambing and lamb BW at birth and at weaning of 0.053 (SE 0.0089) kg and 0.29 (SE 0.049) kg, respectively. Ewes that lambed at 1 year were 2 kg lighter (P < 0.001) at 19 months of age and had a smaller body size (P < 0.01) relative to those not joined. It is concluded that ewe genotype had a significant effect on number of lambs reared, and thus lamb carcass output. Whilst lambing at 1 year reduced BW by 2 kg when joined at 19 months, it did not affect ewe survival to that stage.

Effects of grass and maize silage feed value, offering soybean meal with maize silage, and concentrate feed level in late pregnancy, on ewe and lamb performance.

In many countries, daily herbage accumulation on pasture declines towards zero during the winter period; thus, many pregnant ewes are housed and offered conserved forages supplemented with concentrate prior to parturition. The effects of forage type and feed value (FV), offering soybean meal with maize silage during mid and late pregnancy, and concentrate feed level in late pregnancy on the performance of ewes and their progeny (to slaughter) were evaluated. Ewes (n = 151) were assigned to one of nine treatments from mid-pregnancy until lambing. Medium FV and high FV grass silages (metabolisable energy concentrations of 10.7 and 12.0 MJ/kg DM) were offered ad libitum supplemented with either 15 or 25 kg concentrate/ewe during late pregnancy. Low and high DM maize silages (starch concentrations of 80 and 315 g/kg DM) were offered ad libitum either alone or with soybean meal (200 g/d) and supplemented with 15 kg concentrate during late pregnancy. A final treatment consisted of high FV grass silage supplemented with 5 kg soybean/ewe over the final 4 weeks of pregnancy. Ewes and lambs were put to pasture in a rotational-grazing system within 3 days of lambing. There were no interactions (P > 0.05) between grass silage FV and concentrate feed level for ewe or lamb traits. Increasing grass silage FV increased food intake (P < 0.001) during late pregnancy, ewe BW and body condition score (BCS) at lambing (P < 0.001), lamb BW at birth (P < 0.001) and weaning (P < 0.05), and reduced age at slaughter (P = 0.06). Increasing concentrate feed level increased metabolisable energy (P < 0.05) intake during late pregnancy but had no effect (P > 0.05) on ewe or lamb performance. Increasing maize DM at harvest and offering soybean meal with maize silage increased food intake (P < 0.001) and ewe BW and BCS at lambing (P < 0.05 or P < 0.01). Offering soybean meal with maize silage increased lamb BW at birth (P < 0.01) and reduced age at slaughter (P < 0.05). Reducing supplementation of high FV grass silage to 5 kg of soybean meal had no effect (P > 0.05) on animal performance. Replacing grass silage with maize silage did not affect (P > 0.05) BW gain of lambs. It is concluded that increasing the FV of the grass silage offered during pregnancy had the greatest positive impact on ewe and lamb performance.

Comparative Study of Dissolution for Cannabidiol in EU and US Hemp Oil Products by HPLC.

For the first time, a simple and robust HPLC method has been developed for dissolution studies for cannabidiol (CBD) in hemp oil products. An isocratic elution of samples performed on SOLAS™ C18 150 mm x 4.6 mm, 5 µm column with a mobile phase consisting of 75:25 acetonitrile-water v/v, delivered at a flow rate 1.5 mL/minutes to variable wavelength detector using 214 nm. An in-house validated assay test was executed for calculating the purity of hemp oil products and also for considering the dissolution medium to be used. For dissolution studies, equivalent of 5 mg and/or 10 mg of the active was introduced into 500 mL of simulated gastric and intestinal fluids separately, and dissolution was performed at 50 rpm using paddles for 180 min. Dissolution profiles for hemp oil products purchased from the United States and Europe were compared. Additionally, dissolution testing was conducted to study the effect of percentage CBD release on increased agitation speed of 75 and 100 rpm and also, on extended dissolution runtime of 240 min.

The safety and efficacy of arformoterol and formoterol in COPD.

This study evaluated the safety and efficacy of arformoterol and formoterol over 6-months in subjects with COPD. In a multi-center, 6-month randomized, double-blind, double-dummy trial, subjects with COPD (mean FEV(1) 1.21 L, approximately 41.0% predicted) were randomized to receive either nebulized arformoterol (15 microg BID [n = 149][ARF 15], 25 microg BID [n = 147][ARF 25]), or racemic formoterol (12 microg BID [n = 147][FORM]) delivered by DPI. The proportion of subjects with any post-treatment adverse event for ARF 15, ARF 25 microg, and FORM was 67.8%, 76.2% and 66.7%, respectively, and those with at least one COPD exacerbation was 32.2%, 30.6%, and 22.4%, respectively. Pulmonary function improved for all treatment groups and was maintained throughout the study. Mean change from baseline at 6-months for ARF 15, ARF 25 and FORM in peak FEV(1) was 0.30L, and 0.34L, and 0.26L, respectively, in 24-hour trough FEV(1) was, 0.10L, 0.14L, and 0.09L, and in inspiratory capacity was, 0.20L, 0.37L, and 0.23L. Dyspnea, (mean Transition Dypsnea Index (TDI) focal score) improved in all treatment arms (ARF 15: 1.4, ARF 25: 1.5, and FORM: 1.4) at 6 months, as did rescue short-acting beta(2)-agonists use (mean range: -1.1 to -1.3 actuations/day) and ipratropium bromide (mean range: -0.3 to -0.8 actuations/day). Health status, measured by St George's Respiratory Questionnaire, improved from baseline at 6-months in all treatment groups (mean change: -3.7 to -6.8). In this 6-month study, arformoterol and formoterol were well-tolerated, and their use was associated with improvement in pulmonary function and health status in subjects with COPD with no apparent development of tolerance.

Natural Distribution of the Ixodes dammini spirochete.

Spirochetes believed to be the cause of Lyme disease were isolated from white-footed mice and white-tailed deer, the preferred natural hosts of Ixodes dammini, the tick vector. Evidence suggests that deer act as a reservoir of the disease and provide an overwintering mechanism for both spirochetes and adult ticks. Some tick larvae may acquire the spirochete by transovarial passage and the nymphal stage may transmit the disease to humans.

Relationship between in vitro sperm functional tests and in vivo fertility of rams following cervical artificial insemination of ewes with frozen-thawed semen.

Several procedures have been proposed to assess structural and functional characteristics of cryopreserved ram semen but none so far have yielded consistent relationships with in vivo fertility. The objectives of this study were to evaluate several sperm function tests as potential markers of in vivo ram fertility (determined by pregnancy rate in ewes) using frozen-thawed semen. In experiment 1, frozen-thawed straws (n=3 per ram) of semen from three high and three low fertility rams were assessed using fluorescent microscopy for (1) progressive motility, (2) viability and, (3) acrosomal status. In experiment 2, frozen-thawed straws (n=3 per ram) of semen from 18 rams of known fertility were analysed using either computer-assisted sperm analysis (CASA) for eight motion characteristics or flow cytometric staining for: (1) viability and acrosomal status, (2) plasma membrane status and capacitation-like changes, and (3) live cells following an osmotic resistance test (ORT). In experiment 3, platelet-activating factor (PAF) was isolated from straws (n=2 per ram) of semen using high-pressure liquid chromatography (HPLC) and quantified using HPLC-tandem mass spectrometry for 18 rams. In experiment 1, no association was found between motility, viability (% live) or acrosomal status (% damaged, % intact and % reacted) and in vivo fertility. In experiment 2, no correlation was found between motility (CASA), viability (% live), acrosomal status (% live, % live intact and % reacted), capacitation status (% capacitated, % non-capacitated), plasma membrane stability (% dead) and % live cells following ORT and ram in vivo fertility. In experiment 3, there was no relationship between PAF content in spermatozoa and ram fertility. In conclusion, we were unable to relate the in vivo fertility of rams with in vitro functional tests of their frozen-thawed semen and suggest that the fertility of a given semen sample cannot easily be quantified using available in vitro tests.

Plane of nutrition during the rearing phase for replacement ewes of four genotypes: II - effects on performance during first pregnancy and to weaning, and of their progeny.

Plane of nutrition (PN) offered to ewe replacements during the rearing phase (8 to 17 months) and first pregnancy may affect reproductive and progeny performance when replacements are joined at ~19 months. The effects of PN offered to spring-born ewe replacements during their first winter (winter_1), second summer (summer_2) and subsequent winter (mid and late pregnancy; winter_2) were evaluated, over 3 consecutive years, using 287 ewe lambs of four genotypes: Charmoise×Scottish Blackface (C×SBF), Belclare×SBF (Bel×SBF), Belclare (Bel) and Belclare×SBF (heterozygous for a gene, either FecGH or FecXG mutations, that increases ovulation rate: BelMG×SBF). Ewe lambs were offered, daily, a deferred-grazed herbage allowance (HA) of either 0.75 or 1.75 kg dry matter during winter_1. During summer_2 the replacements were set-stocked to maintain sward heights of 4 or 6 cm. Ewes were housed during mid and late pregnancy (winter_2) and offered either medium or high-feed-value grass silage, thus yielding a 2×2×2 factorial design. Increasing HA during winter_1 and residual sward height during summer_2 increased ewe BW post joining (P0.05) on number of lambs reared. Increasing HA during winter_1 increased lamb BW at birth (P<0.05) and reduced carcass fat score (P<0.05). There was a significant interaction between PN offered during winter_1 and summer_2 for average daily gain (ADG) from birth to 5 weeks (P<0.01) and from 5 to 10 weeks (P<0.05): progeny of replacements that experienced either a high or low PN throughout the rearing phase had lower ADG than lambs born to the replacements that experienced a low PN only during winter_1 or summer_2. Increasing PN during winter_2 increased ewe BW (P<0.001), lamb BW at birth (P<0.001) and weaning (P<0.05) and reduced the proportion of ewes that failed to lamb (P<0.01). Ewe genotype had a significant (P<0.001) effect on litter size (1.48 to 2.45), number of lambs reared, lamb BW at birth and weaning, lamb ADG and age at slaughter. It is concluded that, among the nutrition treatments examined, increasing PN during mid and late pregnancy had the greatest effect on ewe and progeny performance. Although increasing PN offered during winter_1 increased lamb birth BW, PN offered during summer_2 had no effect on lamb performance. There were no significant interactions between PN and ewe genotype.

Plane of nutrition during the rearing phase for replacement ewes of four genotypes: I - effects on growth and development, and on ovulation rate at first joining.

Plane of nutrition (PN) offered to ewe replacements during the rearing phase (8 to 17 months) affects BW at joining and may affect reproductive performance when joined at ~19 months. The effects of PN offered to ewe replacements during their first winter (winter_1) and second summer (summer_2) were evaluated over 3 consecutive years, using 287 spring-born ewe lambs, representing four genotypes (Belclare (Bel), Charmoise×Scottish Blackface (C×SBF), Bel×SBF (Bel×SBF), Bel×SBF that were heterozygous either FecGH or FecXG mutations that increase ovulation rate (OR) (BelMG×SBF)). During extended (deferred) grazing in winter_1 (November to March) the lambs were offered herbage DM allowances (HA) of 0.75 (L) or 1.75 (H) kg/day. During summer_2 (March to August) the replacements were set stocked to maintain sward heights of 4 (L) or 6 (H) cm, thus yielding a 2×2 factorial design for the nutrition treatments (71 to 73 animals/treatment). Increasing HA during winter_1, and residual sward height during summer_2, increased (P0.05) on OR. Mean BW at joining was 53.3, 56.8, 56.6 and 61.7 (SEM 0.74) kg for ewes offered the LL, LH, HL and HH treatments, respectively. Mean OR of C×SBF and BelMG×SBF differed (P<0.001) from that of Bel×SBF by -0.58 and +0.47, respectively. Correlations between linear measurements (LMs) of body size and BW at 7, 12 and 17 months were all positive and significant (P<0.001). The precision of the set of LMs as a predictor of BW at joining improved with age (R 2 0.46, 0.54 and 0.74 at 7, 12 and 17 months) but BW at a given age was a better predictor at all age time points. Chest girth was the best predictor, among the LMs, of BW at joining and its explanatory power increased with age. Equations developed using LMs at 7, 12 or 17 months, to predict BW at joining exhibited biases of -2.1, -1.5 and +0.9 kg, respectively. It is concluded that whilst altering PN during the rearing phase changed BW by 16% it had no effect on OR. There was no interaction (P>0.05) between the PN offered during winter_1 and summer_2, or PN and ewe genotype for BW at joining or OR. LMs, either at 7, 12 or 17 months of age, are useful predictors of BW at joining.

Preoperative gastric residual volumes in fasted patients measured by bedside ultrasound: a prospective observational study.

The purpose of this prospective observational study was to measure gastric volumes in fasted patients using bedside gastric ultrasound. Patients presenting for non-emergency surgery underwent a gastric antrum assessment, using the two-diameter and free-trace methods to determine antral cross-sectional area (CSA). Gastric residual volume (GRV) was calculated using a validated formula. Univariate and multivariable analyses were performed to examine any potential relationships between 'at risk' GRVs (>100 ml) and patient factors. Two hundred and twenty-two successful scans were performed; of these 110 patients (49.5%) had an empty stomach, nine patients (4.1%) had a GRV >100 ml, and a further six patients (2.7%) had a GRV >1.5 ml/kg. There was no significant relationship between at risk GRV and obesity, diabetes mellitus, gastro-oesophageal reflux disease or opioid use, although our study had insufficient power to exclude an influence of one or more of these factors. Our results indicate that despite compliance with fasting guidelines, a small percentage of patients still have GRVs that pose a pulmonary aspiration risk. Anaesthetists should consider this background incidence when choosing anaesthesia techniques for their patients. While future observational studies are required to determine the role of preoperative bedside gastric ultrasound, it is possible that this technique may assist anaesthetists in identifying patients with 'at risk' GRVs.

Is there a relationship between prion protein genotype and ovulation rate and litter size in sheep?

The identification of an association between polymorphisms of the prion protein (PrP) gene and susceptibility to scrapie has enabled the development of breeding programmes to increase natural resistance to scrapie. It is, however, imperative to identify if such selection would affect important reproduction and production traits. The objective of this study was to determine if there is a relationship between polymorphisms at codons 136, 154 and 171 of the PrP gene and ovulation rate or litter size in sheep. Data were collected from a mixed-aged flock of Belclare ewes, over a 9-year period. Ovulation rate was determined annually using laparoscopy by counting the number of corpora lutea at each of two consecutive oestrous cycles, one immediately before and one after mating (2418 records from 366 ewes). Litter size was recorded at parturition (875 records from 353 ewes). The five common PrP alleles were present in the population and 14 PrP genotypes were represented among the animals studied. There was no significant overall effect of PrP genotype on ovulation rate or litter size and pairwise comparisons among genotypes did not reveal any significant differences for either trait. These data suggest that breeding programmes based on selection for specific polymorphisms of the PrP gene will not influence ovulation rate or litter size, at least in the breed studied.

Hormonal relationships during the periovulatory period among ewe breeds known to differ in fertility after cervical artificial insemination with frozen thawed semen.

Our previous work indicates that ewe breed differences in fertility following cervical AI with frozen-thawed semen are due to failure of normal sperm transport and/or early embryo development. Here we examined differences in hormone concentrations about the time of ovulation among more (Finnish Landrace and Belclare) and less (Suffolk and Texel) fertile ewes after AI with frozen thawed semen. In Experiment 1, oestradiol concentrations were measured in samples collected frequently from 12h before to 18h after the LH surge and progesterone was measured in samples collected from 9 to 27h after the LH surge in Suffolk (n=24), Texel (n=20) and Finnish Landrace (n=27) ewes. In Experiment 2, oestradiol concentrations were measured in samples collected frequently from 24h before to 6h after the LH surge and progesterone was measured in samples collected from 6h to 6 days after the LH surge in Suffolk (n=35) and Belclare (n=30) ewes. In Experiment 1, there was an effect of breed, time and their interaction (P<0.001) on oestradiol concentrations between -12 and +6h but only breed differences at +12 and +18h (P<0.01). Progesterone concentrations increased over time (P<0.001) and the rate of increase was significantly greater in Finnish Landrace than in the other two breeds. In Experiment 2, oestradiol concentrations were unaffected by breed. There was an interaction between breed and time with the rate of increase of progesterone being greater in Belclare than Suffolk ewes (P<0.001). In conclusion, differences in hormone concentrations in the periovulatory period are not consistent with ewe breed differences in fertility; however, we have showed that progesterone concentrations rise earlier in the more prolific breeds and suggest that this may explain reported ewe breed differences in embryo development.

Resuspending ram spermatozoa in seminal plasma after cryopreservation does not improve pregnancy rate in cervically inseminated ewes.

The role of seminal plasma (SP) components on the maintenance of motility, viability and fertilising ability of frozen-thawed spermatozoa is of considerable interest. However, differences observed in constituents of SP among males could explain differences in fertility obtained in vivo. Two experiments were designed to examine the effects of seminal plasma on fertility from cervically inseminated frozen-thawed semen. The objective of Experiment 1 was to investigate if source or type of SP influences pregnancy rate. Seminal plasma was collected from rams previously classified as having either High (HSP; n=3) or Low (LSP; n=3) fertility in vivo. Artificial SP (fructose/sodium solution with 10% BSA; ASP) was made. Frozen semen from the same 6 rams was thawed and inseminated (Control) or resuspended either in HSP, LSP or ASP (20% in semen) prior to insemination of ewes (n=284, over 2 farms). The overall pregnancy rate was 28.1%. Treatments (Control, ASP, HSP and LSP) were not significantly different (P>0.3). There was no difference between HSP and LSP (P>0.5), and no effect of using ASP compared to ram SP (P>0.7), on pregnancy rate. As there was no effect of SP on pregnancy rate a repeat experiment (Experiment 2) was designed to test the effect of washing and selecting motile sperm prior to resuspending in phosphate-buffered saline (PBS) containing SP on pregnancy rate. Frozen-thawed semen from each of 2 rams was centrifuged through a density gradient, pellets were centrifuged through a wash medium and the sperm concentration/ram was counted. Sperm cells were resuspended in: (1) control PBS, (2) PBS containing 30% HSP or (3) PBS containing 30% LSP to give 100 x 10(6) motile sperm in 0.25 mL. Control straws were thawed and inseminated directly. Ewes (n=223 over 2 farms) were inseminated 57 h post-sponge withdrawal and those not returning to oestrus were slaughtered 29-50 days post-insemination for pregnancy determination. In Experiment 2, the pregnancy rate for Control, PBS, HSP and LSP were 15.4%, 2.3%, 0% and 0%, respectively, for Farm 1 (P>0.05) and 17.8%, 11.0%, 3.9% and 12.4%, respectively, for Farm 2. Under the conditions of the current study, addition of SP from different donors of either High or Low fertility status to frozen-thawed ram semen post-thawing did not improve pregnancy rate in ewes. ASP had no effect on pregnancy rate in ewes when added to frozen-thawed semen. Washing and selection of motile sperm prior to resuspension in PBS with or without SP (30%) before insemination had a negative effect on pregnancy rate in cervically inseminated ewes. Hence, the addition of seminal plasma or some of its constituents to semen does not appear to improve pregnancy rate in cervically inseminated ewes.

Cobalt supplementation, alone or in combination with vitamin B and selenium: Effects on lamb performance and mineral status.

The effects of supplementing lambs with Co, either alone or in combination with vitamin B and Se, were evaluated over the period from weaning to selection for slaughter. Two hundred and five recently weaned (at 14 wk [SD 0.44] of age), spring-born lambs of various crossbred genotypes were stratified, within genotype, by BW and gender and allocated to 3 groups, which were then allocated at random to one of the following treatments: no supplement (Control), a supplement containing Co only (Co-only), or a supplement containing Co, vitamin B, and Se (VitMin). The concentration of Co in the Co-only supplement was 2.1 mg/mL (as cobalt sulfate); the VitMin supplement contained Co (10 mg/mL, as cobalt acetate), vitamin B (200 µg/mL), and Se (0.25 mg/mL, as sodium selenite). Lambs on the Co-only and VitMin treatments received, every 14 d, 10 and 2.1 mL, respectively, of oral drench. Lambs were managed in a rotational-grazing system from 12 July (swards predominantly ) and selected for slaughter, on the basis of BW, after 45, 73, or 115 d; all remaining lambs were slaughtered on d 157. Supplementation, with Co-only or VitMin, increased BW at slaughter ( < 0.01), ADG ( < 0.001), carcass weight ( < 0.001), dressing percentage ( < 0.001), carcass fat score ( < 0.05), and the proportion selected for slaughter by d 73 ( < 0.05) and 115 ( < 0.01). Relative to the Control, the benefit to ADG from supplementation increased as the season advanced. Therefore, supplementation did not alter ( = 0.82) ADG between d 1 and 45 but increased ADG over the intervals d 45 to 73 ( < 0.01), d 73 to 115 ( < 0.001), and d 115 to 157 ( < 0.001). There was no difference ( > 0.05) between the Co-only and the VitMin treatments for ADG, carcass weight, fat score, or dressing percentage. Supplementation with Co increased liver Co concentration ( < 0.001), and lambs supplemented with VitMin had greater liver Co concentration than lambs supplemented with Co-only ( < 0.05); the concentrations were 0.18, 0.85, and 1.18 µmol/L for the Control, Co-only, and VitMin treatments, respectively. Treatment had no effect ( = 0.65) on the concentration of Se in kidney tissue. It is concluded that supplementation with Co increased lamb performance after weaning, that response to supplementation increased as the grazing season progressed, and that no extra benefit in performance resulted from augmenting supplementary Co with B and Se.

Texel sheep are more resistant to natural nematode challenge than Suffolk sheep based on faecal egg count and nematode burden.

Limited information is available on differences between sheep breeds with respect to helminth resistance under temperate conditions. The present study was designed to confirm and extend preliminary findings on observed breed differences in resistance to naturally acquired gastrointestinal nematodes in Suffolk and Texel sheep. Three trials were carried out. In trial 1 (1999-2003) lambs co-grazed from birth were faecal sampled at various time points up to 17 weeks of age. Worm burden was assessed at 17 weeks of age from a minimum of six lambs per breed in each of the 3 years. In trial 2, faecal egg count (FEC) was determined on six farms with co-grazed Suffolk and Texel purebred lambs. In trial 3 (2001-2003), ewes were faecal sampled at winter housing. In all three trials, an influence of breed on resistance to naturally acquired trichostrongyle infection was demonstrated. In trial 1, significantly higher FEC and worm burden was observed in Suffolk compared with Texel lambs following natural challenge. In trial 2, FEC recorded in lambs from six farms confirmed the breed differences previously observed. A breed difference in resistance to GI parasites was also observed in older ewes. In both breeds, an age effect on the FEC was observed with younger ewes having greater FEC than older ewes.