Romney Ewes Research Articles

Should lambs born to one-year-old ewes and grown to heavy live weights be retained as replacements and mated at seven months of age?

ABSTRACT The lifetime productivity and efficiency of singleton- and twin-born ewe lambs born to one-year-old ewes were compared with twin-born ewe lambs born to mixed-age ewes. Romney ewe lambs either born as twins to mixed-age ewes (Heavier n = 135 and Control n = 135), or to one-year-old ewes as singletons (L1; n = 135) or twins (L2; n = 88) were included. The Heavier ewes weighed 47.9 ± 0.36 kg at ewe lamb breeding while Control ewes weighed 44.9 ± 0.38 kg. The lifetime number of lambs born and weaned, and the lifetime weight of lambs weaned were used to calculate both feed and ewe efficiency. Heavier ewes had greater lamb production as one-year-old ewes than L1, L2 and Control ewes, after which the yearly lamb production and efficiency did not differ between treatments. Heavier ewes had a greater lifetime number and weight of lambs weaned than L1 and L2 ewes but did not differ from Control ewes. The lower lifetime production of L1 and L2 ewes was driven by their low production as one-year-old ewes. Farmers, therefore, could select their replacements from ewes born to one-year-old ewes and have similar lamb production to ewes born to mixed-age ewes, providing they reach recommended pre-breeding live weights.

Combined Growth Factor Hydrogel Enhances Rotator Cuff Enthesis Healing in Rat But Not Sheep Model.

We hypothesized that a combined growth factor hydrogel would improve chronic rotator cuff tear healing in a rat and sheep model. Insulin-like growth factor 1, transforming growth factor β1, and parathyroid hormone were combined into a tyraminated poly-vinyl-alcohol (PVA-Tyr) hydrogel and applied directly at the enthesis. In total, 30 Sprague-Dawley rats and 16 Romney ewes underwent unilateral rotator cuff tenotomy and then delayed repairs were performed after 3-4 weeks. The animals were divided into a control group (repair alone) and treatment group. The rotator cuffs were harvested at 12 weeks after surgery for biomechanical and histological analyses of the repair site. In the rat model, the stress at failure and Young's modulus were higher in the treatment group in comparison with the control group (73% improvement, p = 0.010 and 56% improvement, p = 0.028, respectively). Histologically, the repaired entheses in the treatment group demonstrated improved healing with higher semi-quantitative scores (10.1 vs. 6.55 of 15, p = 0.032). In the large animal model, there was no observable treatment effect. This PVA-Tyr bound growth factor system holds promise for improving rotator cuff healing. However, our approach was not scalable from a small to a large animal model. Further tailoring of this growth factor delivery system is still required. Level of Evidence: Basic Science Study; Biomechanics and Histology; Animal Model Impact Statement Previous studies using single-growth factor treatment to improve enthesis healing after rotator cuff repair have reported promising, but inconsistent results. A novel approach is to combine multiple growth factors using controlled-release hydrogels that mimic the normal healing process. In this study, we report that a combined growth factor hydrogel can improve the histological quality and strength of rotator cuff repair in a rat chronic tear model. This novel hydrogel growth factor treatment has the potential to be used in human clinical applications to improve healing after rotator cuff repair.

The Behaviour of Sheep around a Natural Waterway and Impact on Water Quality during Winter in New Zealand.

Access of livestock, such as cattle, to waterways has been shown to be a cause of poor water quality due to pugging damage and excretion entering the water. In New Zealand, regulations require that cattle, deer, and pigs are excluded from accessing waterways, but there are no such requirements for sheep. The current study utilised 24 h video cameras, global positioning system units, and triaxial accelerometers to observe the interaction of Romney ewes (n = 40) with a natural waterway. Ewes were either restricted (week 1) or given access to a reticulated water trough (week 2). Proximity data showed that ewes spent more time within 3 m of the waterway when the trough was unrestricted than when restricted (14.1 ± 5.7 and 10.8 ± 5.1 min/ewe/day, respectively; p < 0.05). Ewes travelled shorter distances on the steeper areas of paddock than flatter areas. Similarly, ewes showed a spatial preference for the flat and low sloped areas of the paddock. Concentrations of suspended sediment and total phosphorus were higher during access to a reticulated water trough which coincided with the week with more rainy days. Phosphorus and E. coli concentrations in the stream water samples were the above recommended Australian and New Zealand Environment and Conservation Council water quality guidelines, especially after rainy days, but did not appear to be directly related to sheep activity. Overall, the results suggest that during winter, ewes interacted very little with the waterway and were thus unlikely to influence the levels of nutrient and pathogens in the waterway.

Genome-Wide Association Studies of Live Weight at First Breeding at Eight Months of Age and Pregnancy Status of Ewe Lambs.

This study estimated genetic parameters and identified candidate genes associated with live weight, and the occurrence of pregnancy in 1327 Romney ewe lambs using genome-wide association studies. Phenotypic traits considered were the occurrence of pregnancy in ewe lambs and live weight at eight months of age. Genetic parameters were estimated, and genomic variation was assessed using 13,500 single-nucleotide polymorphic markers (SNPs). Ewe lamb live weight had medium genomic heritability and was positively genetically correlated with occurrence of pregnancy. This suggests that selection for heavier ewe lambs is possible and would likely improve the occurrence of pregnancy in ewe lambs. No SNPs were associated with the occurrence of pregnancy; however, three candidate genes were associated with ewe lamb live weight. Tenascin C (TNC), TNF superfamily member 8 (TNFSF8) and Collagen type XXVIII alpha 1 chain (COL28A1) are involved in extracellular matrix organization and regulation of cell fate in the immune system. TNC may be involved in ewe lamb growth, and therefore, could be of interest for selection of ewe lamb replacements. The association between ewe lamb live weight and TNFSF8 and COL28A1 is unclear. Further research is needed using a larger population to determine whether the genes identified can be used for genomic selection of replacement ewe lambs.

Longitudinal study of the effect of sporidesmin toxicity on lamb production and serum biochemistry in a flock of 46 Romney ewes using a standardised measure of liver damage

ABSTRACT Aims To evaluate the effect of sporidesmin toxicity on production outcomes and serum biochemistry analytes in mixed age Romney ewes, using a standardised measure of liver damage. Methods This was a prospective longitudinal study following 46 mixed age Romney ewes from sporidesmin intoxication in April 2019, to slaughter 8 months later. The ewes were blood-sampled up to eight times, with a panel of serum biochemistry tests performed on the final six samples. However, only gamma-glutamyl transferase (GGT) activity was measured in the first two samples collected at the end of sporidesmin intoxication and 2 weeks later. Body condition score, ewe weight and production data were also recorded. Using a standardised liver score, based on histology of liver samples collected at slaughter, ewes were assigned to one of three liver disease categories (LDC); low, middle, and high. These were then used as the outcome or predictor variables for statistical analyses. Finally, two separate decision tree models, using recursive partitioning (RP), were fitted to the biochemistry data and to the GGT data collected at FE outbreak, to predict ewes in the low LDC. Results There was no evidence of a difference for the effect of LDC on ewe weight (p = 0.86) with ewes, on average, gaining weight to weaning. Weaning percent, lamb rearing percent and ewe flock efficiency were lower in ewes with high LDC, and scanning-to-weaning lamb loss was significantly higher in sheep with high LDC (p = 0.02). Serum activities of GGT and glutamate dehydrogenase and concentration of globulin were significantly lower in sheep with low LDC than in sheep with middle or high LDC (p < 0.05). However, there was no evidence of a difference for the effect of LDC on other biochemistry variables (p > 0.05). The final RP model for the biochemistry data categorised ewes as low LDC if their GGT was <122 IU/L, 3 months after sporidesmin intoxication, or if their GGT was <514 IU/L, <18 days after sporidesmin intoxication. Conclusions and clinical relevance Sheep with gross and histological evidence of severe sporidesmin-induced liver damage were able to maintain or gain body weight, suggesting that sporidesmin intoxication alone is not causative of poor body condition. Similarly, many of the serum biochemistry tests were not associated with evidence of liver damage. Lamb production was reduced in ewes with evidence of severe liver damage and the decision tree model showed promise as a basis to select ewes for culling.

Effect of Breeding Heavier Romney Ewe Lambs at Seven Months of Age on Lamb Production and Efficiency over Their First Three Breeding Seasons.

Simple SummaryThis experiment examined the impact of breeding heavier ewe lambs on lamb production and the ability of a ewe to produce a high number and heavier lambs (i.e., efficiency) over the first three breeding seasons. Two groups of ewe lambs were bred at seven months of age at an average live weight of either 47.9 ± 0.36 kg (n = 135) or 44.9 ± 0.49 kg (n = 135). Ewe live weight, number of lambs born and weaned, and lamb live weights were recorded, and ewe efficiency was calculated for each ewe. The weight and number of lambs at weaning over the three-year period did not differ between treatments, however, when data were pooled, heavier ewe lambs at breeding had a greater number and lamb weaning weight over the three-year period. Breeding heavier ewe lambs had no effect on ewe efficiency. There was a positive relationship between ewe lamb breeding live weight and their mature weight. These results suggest that breeding heavier ewe lambs increased the total lamb production over the three-year period, however, it had no effect on ewe efficiency. Before final recommendations can be made, ewe lifetime performance and longevity of heavier ewe lambs at breeding are required.This experiment examined the effect of breeding heavier ewe lambs on lamb production and their efficiency over their first three breeding seasons. Two groups of ewe lambs were bred at seven months of age at an average pre-breeding live weight of either 47.9 ± 0.36 kg (heavy; n = 135) or 44.9 ± 0.49 kg (control; n = 135). Ewe live weight, number of lambs born and weaned, and lamb live weight were recorded until 39 months of age, and efficiency was calculated for each ewe. Although the number and lamb weaning weight did not differ between treatments over three years, when data were pooled, heavier ewe lambs at breeding weaned a greater number of lambs over the three-year period. The total lamb weaning weight over the three-year period increased by 2% for each additional kilogram at ewe lamb breeding. Breeding heavier ewe lambs had no effect on efficiency. These results suggest that although breeding heavier ewe lambs had a positive effect on lamb production over the three-year period, it had no effect on efficiency. Before final recommendations can be made, lifetime performance and longevity to five years of age of heavier ewe lambs at breeding are required.

Effect of Palpable Udder Defects on Milk Yield, Somatic Cell Count, and Milk Composition in Non-Dairy Ewes.

Simple SummaryThe occurrence of udder defects in ewes impacts the productive lifespan of the affected ewe and reduces their lamb production. This study investigated the effects of palpable udder defects on milk yield and milk composition in Romney ewes. The findings showed that the effect of udder-half defects on udder-half milk yield was substantial; however, there was no difference in individual (whole udder) ewe milk production between ewes with one udder-half defective and both normal udder-halves. This was due to a compensatory increase in milk production of the normal udder half when the other udder half was defective, with the exception being ewes that retained the defects for several weeks. No notable difference in milk composition was observed between defective and normal udder halves, except for solids non-fat (SNF). This study shows that udder defects affect milk production in non-dairy ewes, highlighting the potential effects on lamb production.In non-dairy ewes, udder defects hinder the survival and weight gain of their pre-weaned lambs. The objectives of this study were to determine the effects of palpable udder defects on milk yield, somatic cell count (SCC), and milk composition in non-dairy Romney ewes. Ewes with a history of udder defects or normal udders were selected for the study. Of a total of 48 ewes that lambed, 30 ewes reared at least one lamb, and were milked six times, once weekly, for the first six weeks of lactation. Udder halves were palpated and scored at each milking event. Multivariate linear mixed models examined the impacts of udder defects on udder-half and whole-udder milk yield, SCC, and milk composition (fat, protein, lactose, total solids, and solids non-fat (SNF)). Across the six examinations, 24.7% of the total 352 udder-half examinations were observed to be defective. Udder halves that were defective at least once produced on average 57.9% less (p < 0.05) milk than normal udder halves, while normal udder halves with a contralateral defective half yielded 33.5% more (p < 0.05) milk than normal udder halves. Successive occurrence of both hard and lump udder defect categories in an udder-half, udder defect detection early in lactation, and a high frequency of udder defect detection were all associated with udder-half milk yield loss (p < 0.05). At the whole-udder level, no differences in milk yield (p > 0.05) were observed between those with one udder-half defective and both normal udder-halves. However, udders in which one udder half was categorised as hard but progressed to lump and remained as lump until 42 days of lactation produced less (p < 0.05) milk compared with normal udders. With the exception of SNF, there were no significant associations (p > 0.05) between milk composition parameters and udder defect. Overall, these findings emphasise the importance of udder health in non-dairy ewes and the potential effect of udder defects on their lambs.

Application of Machine Learning Algorithms to Predict Body Condition Score from Liveweight Records of Mature Romney Ewes

Body condition score (BCS) in sheep (Ovis aries) is a widely used subjective measure of the degree of soft tissue coverage. Body condition score and liveweight are statistically related in ewes; therefore, it was hypothesized that BCS could be accurately predicted from liveweight using machine learning models. Individual ewe liveweight and body condition score data at each stage of the annual cycle (pre-breeding, pregnancy diagnosis, pre-lambing and weaning) at 43 to 54 months of age were used. Nine machine learning (ML) algorithms (ordinal logistic regression, multinomial regression, linear discriminant analysis, classification and regression tree, random forest, k-nearest neighbors, support vector machine, neural networks and gradient boosting decision trees) were applied to predict BCS from a ewe’s current and previous liveweight record. A three class BCS (1.0–2.0, 2.5–3.5, &gt;3.5) scale was used due to high-class imbalance in the five-scale BCS data. The results showed that using ML to predict ewe BCS at 43 to 54 months of age from current and previous liveweight could be achieved with high accuracy (&gt;85%) across all stages of the annual cycle. The gradient boosting decision tree algorithm (XGB) was the most efficient for BCS prediction regardless of season. All models had balanced specificity and sensitivity. The findings suggest that there is potential for predicting ewe BCS from liveweight using classification machine learning algorithms.

Modelling a Transition from Purebred Romney to Fully Shedding Wiltshire-Romney Crossbred.

Simple SummaryA flock of full-fleeced ewes could be bred to shed all their fleece through the repeated crossbreeding of ewes with shedding rams. This shedding flock would then not need to have their low value wool removed, thus reducing the associated expenses. This study used a simulation model to explore changes in the sheep numbers of different crosses, production, cashflow, and profit during the crossbreeding period. It took 12–15 years of crossbreeding to achieve a fully-shedding third or fourth cross flock. Economically, crossbreeding to a shedding flock compared favourably with farming a full-fleeced flock. More data on the performance of shedding sheep in New Zealand would improve the accuracy of model predictions.Considering the current low prices for coarse wool (fibre diameter > 30 µm), a grading up transition to a shedding flock may eliminate wool harvesting costs and increase sheep farm profit. This transition could be achieved by breeding non-shedding ewes with Wiltshire rams. A bio-economic system-dynamics model of a pastoral sheep farming enterprise was used to simulate this grading up transition from 2580 Romney ewes to a similarly-sized flock of fully shedding third or fourth cross Wiltshire–Romney ewes. The total annual sheep feed demand was constrained within a ±5% range to minimise disruption to the on-farm beef cattle enterprise. Wool harvesting expenses were eliminated after seven years of transition, and with reduced feed demand for wool growth, the post-transition shedding flocks had more ewes producing more lambs and achieving greater annual profit compared with the base Romney flock. The net present values of transition were 7% higher than the maintenance of the base Romney flock with a farmgate wool price of $2.15/kg. Results suggest that coarse wool-producing farmers should consider a grading up transition to a shedding flock, and the collection of data on the production of Wiltshire–Romney sheep in New Zealand would improve the accuracy of model predictions.

Palpable udder defects are associated with decreased lamb production in commercial ewes

In pasture-based sheep production systems total weight of lamb weaned impacts flock profitability. Udder defects have been associated with poor lamb survival and lower lamb growth rates to weaning in non-dairy breed sheep. However, it is the combination of these two factors that influences ewe flock productivity and value to the farmer. The objective of this study was to describe associations between ewe udder palpation (normal vs. abnormal; where abnormal is diffuse udder hardness, or palpable lumps(s), on one or both udder halves), and total kilograms of lamb weaned. Mixed-age Romney ewes were enrolled from a commercial sheep flock located near Masterton, Wairarapa, New Zealand, in a two-year prospective observational study; 981 ewes in 2017 and 790 ewes in 2018. In each year, ewes had their udders palpated at four key management times (pre-mating, pre-lambing, tailing and weaning). During the lambing period, twice daily lambing observations were undertaken to match lambs with their dams, while at weaning in each year total weight of lamb weaned per ewe was calculated (where kilograms of lamb weaned equalled the sum of the weight(s) of live offspring at weaning). Analyses used matched methods for each time udder palpation occurred. Each ewe with an abnormal udder was matched to four ewes with normal udders, based on: parturition date, number of lambs born in the litter, and ewe weight and body condition score prior to lambing. The prevalence of ewes with abnormal udder palpations ranged from 2.7% - 7.7% at each of the measurement times. At all management times, ewes that had abnormal udder palpation weaned significantly less total kilograms of lamb compared to ewes that had normal udder palpation. Importantly, pre-mating udder palpations were predictive of total weight of lamb weaned. Ewes with normal udders pre-mating weaned an estimated mean of 42.2 kg and 45.4 kg in 2017 and 2018 respectively, while ewes with abnormal udders weaned 25.8% less lamb (p<0.0001) in 2017 and 33.2% less lamb (p<0.0001) in 2018. These results suggest commercial farmers could use udder palpation prior to mating as a tool to identify and prioritise culling of ewes with palpable udder defects, as these ewes are predicted to have lower lamb production.

Chronic facial eczema in sheep: description of gross and histological changes in the liver and association with serum gamma-glutamyltransferase activity at the time of sporidesmin intoxication

ABSTRACT Aims To determine the gross and histological changes developing in the liver of sheep 8 months after a single period of exposure to sporidesmin and to examine associations between the severity of gross and histological changes to the liver and the activity of gamma-glutamyltransferase (GGT) measured in serum in the sheep at the time of intoxication. Methods A group of 50 Romney ewes grazing a mixed ryegrass/white clover pasture were accidentally exposed to sporidesmin for up to 5 weeks. Seventeen sheep showed photosensitisation and four were subject to euthanasia. The remaining sheep were moved to safer pasture and a blood sample collected and analysed for serum GGT activity. The sheep were slaughtered 8 months later. Livers were classified into grossly normal, moderately affected, or severely affected and histology performed to assess portal fibrosis, biliary hyperplasia, portal inflammation, and hepatocellular necrosis. Results Serum GGT activity ranged from 59 to 1571 IU/L (reference range 32–70 IU/L). Thirteen of the 46 sheep developed clinical signs of facial eczema. However, at slaughter all except four sheep had grossly detectable changes to the shape of the liver including atrophy of the left lobe and the lateral part of the right lobe. Hypertrophy was typically limited to the medial part of the right lobe. In severely affected sheep the liver hypertrophy formed a nodular bulging mass. Changes in the liver shape were classified as severe in 25 and moderate in 17 sheep. Severely affected livers contained significantly more fibrosis than moderately affected livers (p = 0.001, Cliff’s delta (d) = 0.68). While there was significantly greater fibrosis and biliary hyperplasia in the left than right lobes, histological changes were present throughout all samples taken of affected livers. Serum GGT activity taken during acute intoxication were correlated to subsequent fibrosis and biliary hyperplasia. Conclusions Hepatic fibrosis develops in sheep after a single episode of sporidesmin intoxication, even in sheep with only mildly elevated GGT activity at the time of intoxication. Furthermore, the severity of the subsequent hepatic fibrosis was predicted by the degree of elevation of serum GGT activity during intoxication. Clinical relevance More research is required to determine how the presence and severity of hepatic fibrosis affect animal production. However, if hepatic fibrosis does decrease production, the consistent development of fibrosis after sporidesmin ingestion reinforces the importance of avoiding exposure of livestock to sporidesmin. Abbreviations GGT: Gamma-glutamyltransferase; d: Cliff’s delta

Producing higher value wool through a transition from Romney to Merino crossbred ii: Cashflow and profit

• Bio-economic system-dynamics modelling of a Romney flock bred with Merino sires for whole flock breed transition. • Profit decreased during transition, but was greater post-transition than for Romney flock. • Economic benefit of transition ranged from zero to an increase of up to 26 %. • Greatest economic benefit with higher lamb selection intensity and longer transition. • With higher selection intensity, post-transition wool had lower fibre diameter and higher value. Data suggests crossbreeding a Romney ewe flock with Merino sires to achieve a second cross ¾ Merino ¼ Romney (¾M¼R) flock would reduce wool fibre diameter and increase income from wool sales. It is not known how cashflow would vary during such a breed transition and which factors would affect the profitability of such a strategy. A bio-economic system-dynamics modelling study was conducted to simulate the breed transition with low or high selection intensity (24 % vs. 35 % of crossbred ewe lambs not retained at each of two selection events) and either consistent lambing rate (132 % for all flocks) or breed specific lambing rate (lower for Merino-Romney crossbred flocks). Although sheep enterprise profit was always greater post-transition compared with the base Romney flock, during transition annual profit was reduced below that of the base Romney flock. The total cashflow of the breed transition (i.e. twelve years) ranged from relatively small or no economic benefit, to up to 26 % greater than maintenance of the base Romney flock. The most profitable breed transition strategies modelled had higher Merino-Romney ewe lamb selection intensity, achieved greater wool fibre diameter reductions, and occurred over a longer breed transition period.

Producing higher value wool through a transition from Romney to Merino crossbred i: Flock dynamics, feed demand, and production of lambs and wool

Abstract Data suggests crossbreeding a Romney ewe flock with Merino sires to achieve a second-cross ¾ Merino ¼ Romney (¾M¼R) flock could reduce wool fibre diameter to take advantage of increasing medium wool (fibre diameter > 24 μm and

The effect of serum 25-hydroxyvitamin D concentration on fecundity of ewes on a New Zealand sheep farm

Abstract Research on Soay Island sheep showed a positive association of serum 25(OH)D concentration and fecundity, while similar research on Scottish sheep didn’t show an association with fecundity but did show an association with weaned lamb weight. Therefore the aim of this study was to determine if serum 25-hydroxyvitamin D (25(OH)D) concentrations of ewes at mating, on a commercial sheep farm, was associated with subsequent prolificacy. On a sheep and beef farm in the North Island of New Zealand 200 mixed-age Romney ewes (Ovis aries) had weights recorded and blood was collected by jugular venepuncture in April (autumn) at mating. Pregnancy testing was conducted 12 weeks after mating, using real time ultrasound to confirm pregnancy and determine whether the dams were carrying singletons, twins or triplets. Serum 25(OH)D2 and D3 concentrations, total calcium, and phosphorus concentrations were measured in the 200 pregnant ewes. A multinomial logistic regression model was fitted to the data in order to determine significant predictors of the ultrasound scanning result. The mean serum total 25(OH)D concentrations of single, twin and triplet bearing ewes were 102.0 ± 3.4, 101.0 ± 2.4 and 83.0 ± 4.5, respectively. In a multinomial logistic regression model serum total 25(OH)D and 25(OH)D3 concentrations were also negatively correlated with ewes pregnant with triplets (P = 0.015), while weight was significantly associated with both twin and triplet bearing ewes (P The reason for the lower serum 25(OH)D concentration in sheep bearing triplets is unclear, and further research is required in order to determine the mechanisms behind this. The results suggest that an effect on ewe fecundity may only be seen when serum 25(OH)D concentrations are marginal.

Evaluation of infrared thermography as a non-invasive method of measuring the autonomic nervous response in sheep.

Eye temperature measured using infrared thermography (IRT) can be used as a non-invasive measure of autonomic nervous system (ANS) activity in cattle. The objective of this study was to evaluate if changes in eye temperature (measured using IRT) can be used to non-invasively measure ANS activity in sheep. Twenty, 2 to 4-year-old, Romney ewes were randomly assigned to receive either epinephrine (EPI) or physiological saline (SAL) for 5 min administered via jugular catheter (n = 10 ewes/treatment). Eye temperature (°C) was recorded continuously using IRT for approximately 25 min before and 20 min after the start of infusion. Heart rate and heart rate variability, measured using the root mean square of successive differences (RMSSD) and the standard deviation of all inter-beat intervals (SDNN), were recorded for 5 min before and up to 10 min after the start of infusion. Blood samples were taken before and after the infusion period to measure plasma epinephrine, norepinephrine, cortisol and packed cell volume (PCV) concentrations. During the infusion period, maximum eye temperature was on average higher (P<0.05) in sheep that received epinephrine than those that received saline. On average, heart rate was higher (SAL: 87.5 beats/min, EPI: 123.2 beats/min, SED = 7.07 beats/min; P<0.05), and RMSSD (SAL: 55.3 ms, EPI: 17.3 ms, SED = 14.18 ms) and SDNN (SAL: 54.3 ms, EPI: 21.5 ms, SED = 10.00 ms) lower (P<0.05) in ewes during the 5 min post-infusion period compared with ewes that received saline. An infusion of epinephrine resulted in higher geometric mean epinephrine (P<0.05) and cortisol (P<0.05) but not norepinephrine (P>0.05) concentrations in ewes compared to an infusion of saline. PCV concentrations were higher (P<0.001) by 7 ± 1.0% (mean±SED) in ewes after an epinephrine infusion. These results suggest that heart rate variability is a sensitive, non-invasive method that can be used to measure ANS activity in sheep, whereas change in eye temperature measured using IRT is a less sensitive method.

The Effect of Age, Stage of the Annual Production Cycle and Pregnancy-Rank on the Relationship between Liveweight and Body Condition Score in Extensively Managed Romney Ewes.

Simple SummaryLiveweight and body condition score (BCS)) are related, indicating that it may be possible to predict one from the other. The magnitude of this relationship can be altered by animal and environmental factors. The aim of the present study was to determine the nature of the association between liveweight and BCS over time, and the effect of the interaction between the stage of the annual cycle and the age of the ewe, using individual animal records. The association between liveweight and BCS was found to be linear and was affected by the interaction between ewe age, stage of the annual cycle and pregnancy-rank of the ewe. The results highlight the substantial contribution of BCS to the differences in liveweight of the ewe. The findings suggest that when predicting BCS from the liveweight, consideration of these factors is required, and different prediction equations are needed.This study determined the nature of the relationship between liveweight and body condition score (BCS) and assessed the influence of the stage of the annual cycle and pregnancy-rank on the relationship between liveweight and BCS in Romney ewes. Data were collected from the same ewes at different ages (8–18, 19–30, 31–42, 43–54, 55–66 and ≥67 months), stages of the annual cycle (pre-breeding, at pregnancy diagnosis, pre-lambing and weaning) and pregnancy-rank (non-pregnant, single or twin). Linear regression was determined as being sufficient to accurately describe the relationship between liveweight and BCS. Across all data, a one-unit change in BCS was associated with 6.2 ± 0.05 kg liveweight, however, this differed by stage of the cycle, pregnancy-rank and ewe age (p <0.05). The average liveweight per unit change in body condition score increased with the age of the ewe and was greatest at weaning and lowest pre-lambing. Among pregnancy-ranks, the average liveweight per unit change was also greater during pregnancy diagnosis than pre-lambing and was greatest among single and lowest in non-pregnant ewes. The results support the hypothesis that the relationship between liveweight and BCS is affected by the interaction between stage of the annual cycle, pregnancy-rank and ewe age.

Detection and Diagnostic Methods of Multiple Influential Points in Binary Logistic Regression Model in Animal Breeding

Multiple influential points adversely affect parameter estimation in binary logistic regression models and lead to misinterpretation of results. An influential point is a data point that does not follow the overall slope of remaining data and has extreme value in terms of x. Since the presence of approximately 10% of influential points in a dataset affects parameter estimates, detection and diagnosis of these points greatly matter. Graphical (such as scatter graph and box graph) and analytical methods are adopted in the detection and diagnosis of multiple influential points. Among the commonly used diagnostic methods are Pearson residuals, Standardized Pearson Residuals (SPR), Cook Distance (CD), Hat matrix, DFFITS, and DFBETA. However, these methods mask problems and fail to diagnose if there are multiple influential points. Many statisticians have developed and proposed new diagnostic methods, such as Generalized Standardized Pearson Residual (GSPR) and Generalized Weights (GW), to overcome this problem. This study exploited a dataset containing multiple influential points (15%) for weaning weight (WW), yearling weight (YW), fleece weight (FW), and fertility rate (FR) of Romney ewes and modelled the effects of WW, TW and FW variables on FR by binary logistic regression model. This study is intended to determine the multiple influential points by graphical methods and to examine the performance of commonly used and newly developed methods in the diagnosis of these data points. As a result, it was observed that the commonly used methods mask multiple influential points and the new proposed methods competently identify these points.

SCIDOT-35. A NOVEL MODEL FOR THE OPTIMIZATION OF DRUG-DEVICE COMBINATIONS FOR THE TREATMENT OF BRAIN TUMORS

Abstract BACKGROUND Failure of many brain tumor treatments has been attributed to the inability of a compound to cross the blood-brain barrier. Convection-enhanced delivery (CED) offers a method to administer drugs directly to the tumor site, thereby mitigating this limitation. CED has been used in several preclinical and clinical studies, though an approved treatment is yet to come to fruition. A medical device suitable for repeated intraparenchymal delivery is valuable for brain tumor treatment strategies, but a lack of appropriate preclinical models capable of infusing clinically relevant volumes has hindered progress in clinical translation. Currently utilized preclinical models include porcine, which have limited use due to their growth rates and canine and non-human primates, which are restricted by ethical considerations. This study investigates the functional characteristics and stability of the Renishaw clinical Neuroinfuse™ drug delivery system in an ovine model. METHODS A head fixation frame was refined for ovine stereotactic surgery. Eight Romney ewes were implanted with the drug delivery system, comprising of four catheters and a transcutaneous port allowing chronic re-access infusions without repeated surgery. A maximum of four infusions were performed per subject, at four to eight-week intervals. RESULTS The implantation of the Neuroinfuse™ drug delivery system was well-tolerated in all subjects, without serious device related adverse events. Artificial CSF/gadolinium infusions were performed on five subjects. Three subjects were maintained for a follow-up study. Putaminal and thalamic distribution volumes remained stable over the re-access period of up to six months post-implantation. CONCLUSION Romney ewes are suitable for the stereotactic implantation of the Neuroinfuse™ chronic drug delivery system. Transcutaneous ports remained integrated for the study duration, allowing repeated intraparenchymal delivery. This novel preclinical model provides a stable platform for infusion regime optimization of drug-device combinations for chronic CED, which will undoubtably de-risk clinical translation in the neuro-oncology CED field.

Variation in KRTAP6-1 affects wool fibre diameter in New Zealand Romney ewes.

Variation in KRTAP6-1 has been reported to affect wool fibre traits in Merino cross-breed sheep and Chinese Tan sheep, but little is known about whether these effects persist in other breeds. In this study, variation in KRTAP6-1 was investigated in 290 New Zealand (NZ) Romney ewes sired by 16 different rams. Polymerase chain reaction single-stranded conformational polymorphism (PCR-SSCP) analysis revealed four variants (, , and of KRTAP6-1, and nine genotypes (AA, AB, AE, AF, BB, BE, BF, EE and FF) in these ewes. Among the 243 ewes that had genotypes with a frequency of over 5 % (i.e. AA, AB and BB), the presence of was found to be associated with reduced mean fibre diameter (MFD) and increased coefficient of variation in fibre diameter (CVFD), whereas the presence of had a trend of association with decreased coarse edge measurement (CEM). A genotype effect was also detected for MFD and CVFD. No associations were detected for fibre diameter standard deviation (FDSD), mean fibre curvature (MFC) and medulation. These results suggest that variation in KRTAP6-1 affects wool fibre diameter in NZ Romney ewes, confirming the finding in Merino cross-breed sheep.

Evaluation of fetal exposure to external loud noise using a sheep model: quantification of in utero acoustic transmission across the human audio range

There is mounting evidence that neural memory traces are formed by auditory learning in utero and that premature newborns are particularly sensitive to the intense, sustained noises or impulses sounds associated with the use of intensive care equipment. One area of critical importance is the determination of sound level exposure in utero associated with maternal occupation. The attenuation factors provided by the abdomen and tissue as well as the routes by which the inner ear receives stimulation need careful consideration and investigation to provide prenatal protection from external sound levels and frequencies that may cause harm. To measure how sound from external sound sources is transmitted to the fetus inside the uterus of a pregnant sheep in 6 Hz frequency steps between 100 Hz and 20 kHz (ie, across most of the human audio range). We measured acoustic transfer characteristics invivo in 6 time-mated singleton pregnant Romney ewes (gestational age, 103-130 days, weight, 54-74 kg). Under general anesthesia and at hysterotomy, a calibrated hydrophone was attached to the occiput of the fetal head within the amniotic sac. Two calibrated microphones were positioned in the operating theater, close to the head and to the body of each ewe. Initial experiments were carried out on 3 pregnant ewes 3 days after transport recovery to inform the data acquisition protocol. This was followed by detailed data acquisition of 3 pregnant ewes under general anesthesia, using external white noise signals. Voltage signals were acquired with 2 calibrated microphones, located near the head and the body of each ewe and with a calibrated hydrophone located in the amniotic fluid. Measurement of acoustic transmission through the maternal abdominal and uterine walls indicates that frequency contents above 10 kHz are transmitted into the amniotic sac and that some frequencies are attenuated by as little as 3 dB. This study provides new data about in utero sound transmission of external noise sources beyond physiological noise (cardiovascular, respiratory, and intestinal sounds), which help quantity the potential for fetal physiological damage resulting from exposure to high levels of noise during pregnancy. Fine-frequency acoustic attenuation characteristics are essential to inform standards and clinical recommendations on exposure of pregnant women to noise. Such transfer functions may also inform the design of filters to produce an optimal acoustic setting for maternal occupational noise exposure, use of magnetic resonance imaging during pregnancy, and for neonatal incubators.