Identification of risk factors for ewe mortality during the pregnancy and lambing period in extensively managed flocks.

BACKGROUND: Ewe mortality during pregnancy and lambing is an issue for sheep producers globally, resulting in reduced productivity and profitability, compromised ewe welfare, and poor consumer perception. Despite these negative consequences, there was little investigation into factors associated with ewe death during this time. Therefore, this study aimed to assess associations between ewe body condition score (BCS), weight, reproductive parameters, and risk of mortality during pregnancy and lambing. METHODS: Four cohorts from three commercial New Zealand farms participated, with 13,142 ewe lambs enrolled and followed over time. Data were collected for five consecutive lambings. Visits aligned with key on-farm management times, specifically: prior to breeding, at pregnancy diagnosis (PD), prior to lambing (set-stocking), and, at weaning of their lambs. At each visit, ewes were weighed, BCS assessed and reproductive status was recorded when relevant (litter size at PD and lactation status after lambing). Ewes that died or were culled were recorded, and any ewes that were absent from consecutive visits were presumed dead. Logistic regressions were developed to assess the relationship between weight and BCS at each visit, PD result (single or multiple-bearing) and lactation status (wet or dry) in each year, and, risk of mortality during the pregnancy and lambing period in each year. RESULTS: In the PD to weaning period, mortality incidence ranged from 6.3 to 6.9% for two-tooth (18-months-old at breeding) to mixed-age (54-months-old at breeding) ewes. For ewe lambs (7 to 8-months-old at breeding), mortality was 7.3% from set-stocking to weaning. Heavier ewe lambs at PD were less likely to die during lambing (OR: 0.978, p = 0.013), as were those with greater set-stocking BCS. In subsequent years, BCS was a predictor of ewe death, with odds of mortality greatest for ewes < BCS 2.5. Additionally, for poorer BCS ewes, increasing weight reduced risk of mortality, but there was no impact of increasing weight in greater BCS ewes. CONCLUSIONS: This study identified risk factors associated with ewe mortality during the pregnancy and lambing period. Flock owners can use these to either cull at-risk ewes or proactively intervene to reduce likelihood of mortality, thereby improving flock productivity, profitability and welfare.

Ewe wastage in commercial sheep flocks: a review of current knowledge.

Ewe wastage encompasses ewes that do not reach the end of their potential productive lives and is the combination of premature culling and on-farm mortality. Increased ewe wastage results in reduced flock productivity and profitability, primarily driven by the need for increased replacement ewe lambs to maintain flock numbers and the costs associated with these additional replacements (e.g. reduced sale lambs, reduced flock age resulting in lower lamb production, and reduced ability to utilise terminal sires). Annual ewe mortality rates are reported to range from 2.8 to 40.2% in New Zealand commercial flocks, while wastage over a ewe's productive lifespan (i.e. mortality and premature culling combined to 6-7 years-of-age) is reported to be up to 90%. To date, ewe wastage has received relatively little attention in the published literature. This article reviews published studies describing wastage in non-dairy ewes, focusing on New Zealand commercial flocks, although overseas pasture-based data is also considered. The relevance of, and challenges associated with, investigating ewe wastage are discussed. Ewe culling and mortality data is outlined, and causes are described. Known key risk factors for wastage, namely, reproductive performance, udder health, dental health, body condition score and breeding of ewe lambs, are reviewed. Finally, current knowledge gaps and future areas of research are identified and evaluated.

Behaviour of twin- and triplet-born lambs and their dam 3 to 18 hours after birth is not a useful predictor of lamb survival to weaning.

OBJECTIVE: An experiment was designed to determine if behaviour traits expressed by twinand triplet-bearing lambs and their dams at 3 to 18 hours of age (after the immediate ewelamb bonding had occurred) were associated with lamb survival to weaning. METHODS: The behaviour of twin and triplet lambs and their dams was assessed in the paddock at 3 to 18 hours after birth. Observations were made of the number of high- and low-pitched bleats, time to stand, make contact with dam, suck from dam and follow dam were recorded for each lamb. The maternal behaviour score of each dam was assessed. A random sub-sample of lambs were assessed during a maternal-recognition test at 12 or 24 hours of age. Traits included time spent standing, sitting, walking, time taken to reach the ewes and time spent with the ewes as well as the number of high- and low-pitched bleats emitted by the lamb. RESULTS: In the paddock, for each additional second required for twin-born lambs to follow their dam, lambs were 1.004 (95% confidence interval [CI] 1.000 to 1.008) times more likely to survive to weaning (p<0.05). The opposite relationship, however, was seen in triplet lambs. For each additional second required for triplet-born lambs to follow their dam, lambs were 0.996 (95% CI 0.993 to 0.999) times as likely to survive to weaning (p<0.05). During the maternal recognition test, twin-born lambs were 0.989 (95% CI 0.979 to 1.000) times as likely to survive to weaning for every additional second they took to reach the contact zone (p<0.05). Similarly, triplet-born lambs were 0.994 (95% CI 0.989 to 0.999) as likely to survive for every additional second they took to reach their dam (p<0.05). CONCLUSION: All ewe behaviours and the majority of lamb paddock and test behaviours were not associated with the survival of twin- or triplet-born lambs and, therefore, are of little use as indicators of lamb survival to weaning.

Investigating associations between lamb survival to weaning and dam udder and teat scores.

Aims: To examine a range of udder and teat traits in Romney ewes and to describe the frequency with which different scores occur, and to investigate associations between lamb survival to weaning and ewe udder and teat scores. Methods: Mixed-age, mature Romney ewes (n = 1,009) were enrolled from a commercial sheep flock located in the Wellington region of New Zealand in January 2017. A range of udder and teat traits were scored in all ewes, using visual assessment and palpation, at pre-mating (February), pre-lambing (October), docking (November) and weaning (January 2018). During the lambing period each newborn lamb was matched to its dam, with lamb mortalities recorded until weaning. Associations between udder and teat scores and lamb survival to weaning were examined using multivariable models for each udder-scoring time. Results: Records from 981 ewes and 1,822 live-born lambs were included in analyses, with 252 (13.8%) lambs recorded dead between birth and weaning. Lambs born to ewes with pre-mating udder scores of lump or hard had 4.9 (95% CI = 2.6-9.6, p = 0.003) and 3.0 (95% CI = 1.5-6.1, p < 0.001) increased odds of failure to survive to weaning, respectively, compared with lambs whose dams had normal udder scores. Lambs born to ewes with mastitis at docking or weaning had 3.0 (95% CI = 1.5-5.9, p = 0.001) and 3.9 (95% CI = 1.3-11.6, p = 0.013) increased odds of failure to survive to weaning, respectively, compared with lambs whose dams did not have mastitis. Offspring of dams with asymmetrical udders at docking or weaning had 3.3 (95% CI = 2.2-4.9, p < 0.001) and 2.5 (95% CI = 1.5-4.0, p < 0.001) increased odds of failure to survive, respectively, compared with lambs whose dams had symmetrical udders. Conclusion and Clinical Relevance: Pre-mating udder palpation scores of hard or lump were associated with increased odds of lambs not surviving to weaning compared with normal scores, and could be used to identify ewes that are likely to be unsuitable for retaining in the breeding flock. Farmers could also use clinical mastitis scores and udder symmetry scores at docking or weaning to identify ewes whose lambs had greater odds of failure to survive to weaning. However these scores do not provide an indication of future performance, therefore further investigation into the impact of the present season's score on future seasons' lamb survival is required.

Associations between lamb growth to weaning and dam udder and teat scores.

Aims: To investigate associations between lamb growth to weaning and dam udder and teat scores measured at pre-mating, pre-lambing, docking and weaning. Methods: Mature Romney ewes (n = 1,009) were enrolled from a commercial sheep flock located near Masterton, in the Wellington region of New Zealand in 2017. A range of udder and teat traits were scored in all ewes, using visual assessment and palpation, at pre-mating, pre-lambing, docking and weaning. During the lambing period, each newborn lamb was matched to its dam and lamb sex, birthweight and birth-rank were recorded. A rearing rank was allocated to each live-lamb at weaning, when all lambs were weighed (n = 1,570), allowing calculation of daily growth rates (g/day). Associations between udder and teat scores and lamb growth rates to weaning were examined using multivariable models for each udder-scoring time. Results: Growth rates of lambs whose dams had udder palpation scores of hard, or both teats recorded as abnormal, pre-mating were lower than lambs whose dams had normal scores (229.9 (95% CI = 213.2-246.6) vs. 254.5 (95% CI = 245.6-263.5) g/day; p = 0.011) and (227.4 (95% CI = 208.3-246.6) vs. 247.9 (95% CI = 235.7-260.2) g/day; p = 0.024), respectively. Growth rates of lambs whose dams had clinical mastitis at docking or weaning were lower than those without mastitis (215.8 (95% CI = 199.9-231.7) vs. 235.4 (95% CI = 225.4-255.0) g/day; p = 0.007) and (220.0 (95% CI = 205.2-234.8) vs. 254.7 (95% CI = 248.9-260.5) g/day; p < 0.001), respectively. Growth rates of lambs whose dams had asymmetrical udders at docking or weaning were lower than lambs whose dams had symmetrical udders (204.6 (95% CI = 189.7-219.5) vs. 240.2 (95% CI = 225.4-255.0) g/day; p < 0.001) and (223.3 (95% CI = 213.9-232.7) vs. 242.2 (95% CI = 229.4-255.0) g/day; p = 0.014), respectively. Conclusions and Clinical Relevance: Pre-mating udder palpation and teat palpation scores can be used to identify ewes whose lambs are predicted to have lower growth to weaning. Assuming a mean lamb age at weaning of 84.4 days, lambs born to ewes with a pre-mating score of hard would be expected to have a mean weaning weight that was 2.1 kg less than those whose dams had normal scores. Udder palpation, udder symmetry and clinical mastitis scores during lactation were also associated with lamb growth rates. Abbreviation: CALW: Conceptus-adjusted liveweight.

A comparison of liveweight gain of lambs weaned early onto a herb-clover mixed sward and weaned conventionally onto a ryegrass-clover pasture and herb-clover mixed sward.

OBJECTIVE: The aim of the present study was to identify the impact of early weaning of lambs at approximately seven weeks of age onto a herb-clover mix on the liveweight gain of lambs and their dams. METHODS: In 2015, twin-born lambs that weighed a minimum of 16 kg (n = 134) were randomly allocated to one of three treatments: i) Early-weaned (58 days after the midpoint of lambing) onto an unrestricted allowance (>1,200 kg dry matter/ha) of herb-clover mix (HerbEW); ii) Lambs+dams unweaned onto an unrestricted allowance of herb-clover mix until conventional weaning (95 days after the midpoint of lambing) (HerbCW); iii) Lambs+ dams unweaned onto an unrestricted allowance of grass-clover pasture until conventional weaning (GrassCW). In 2016, twin-born lambs that weighed a minimum of 16 kg (n = 170) were randomly allocated to one of four treatments: i), ii), iii) (similar to 2015) and iv) Lambs+ dams unweaned onto a restricted allowance (<1,200 kg dry matter/ha) of grass-clover pasture until conventional weaning (93 days after the midpoint of lambing) (Restricted-GrassCW). RESULTS: In 2015, liveweight gain from L58 to L95 of HerbCW and GrassCW lambs did not differ (p>0.05), but were greater than HerbEW lambs. In 2016, HerbCW lambs had greater (p<0.05) liveweight gains from L51 to L93 than GrassCW followed by HerbEW and Restricted-GrassCW lambs. In 2015, liveweight gain from L58 to L95 of HerbEW ewes were greater than both GrassCW and HerbCW ewes while in 2016, liveweight gain of from L51 to L93 GrassCW and HerbCW ewes did not differ (p>0.05) but were greater (p<0.05) than those of HerbEW and Restricted-GrassCW ewes. CONCLUSION: These results indicate that when grass-clover pasture supply can be maintained at unrestricted intake level, there may be no benefit of weaning lambs early. However, at restricted pasture conditions lambs can achieve greater liveweight gains when weaned early onto a herb-clover mix.

Associations between liveweight, body condition score and previous reproductive outcomes, and the risk of ewes bred at 18-months of age being dry at docking.

AIMS Firstly, to investigate associations between liveweight and body condition score (BCS) of two-tooth ewes (18-months-old at breeding) at breeding, pregnancy diagnosis (PD) and pre-lambing and the risk of being dry at docking, on commercial New Zealand sheep farms. Secondly, to investigate the association between previous reproductive outcomes as ewe lambs, and risk of being dry at docking as two-tooth ewes. METHODS Two-tooth ewes (n=9,006) were enrolled in four cohorts from three commercial sheep farms between 2010-14. Ewes were weighed and BCS assessed immediately pre-breeding, at PD (mid-pregnancy) and pre-lambing. At PD, ewes were identified as either non-pregnant, or having single or multiple fetuses. Palpation and examination of udders at docking was used to classify each ewe as either lactating or dry at docking. RESULTS Overall, 437/8,025 (5.4%) of ewes that were diagnosed pregnant at PD were dry at docking. The risk of being dry at docking decreased with increasing pre-lambing conceptus adjusted liveweight (CALW) on all farms (p≤0.002); for 2010-born ewes from Farm A the OR=0.87 (95% CI=0.81-0.92); for Farm B the OR=0.88 (95% CI=0.83-0.92) and for Farm C the OR=0.86 (95% CI=0.79-0.95). The risk of being dry at docking also decreased with increasing CALW gain from PD to pre-lambing for all farms (p≤0.003); for 2010-born ewes from Farm A the OR=0.89 (95% CI=0.84-0.94); for Farm B the OR=0.85 (95% CI=0.81-0.89) and for Farm C the OR=0.88 (95% CI=0.80-0.96). There was no association between BCS at breeding, PD or pre-lambing and the risk of being dry at docking for 2010-born ewes from Farm A, Farm B or Farm C (p>0.05). For 2010-born ewes on Farm A, the risk of being dry at docking was greater for two-tooth ewes that were previously dry at docking as ewe lambs than those that were lactating at docking as ewe lambs (OR=1.7 (95% CI=1.1-2.8); p=0.018), but this difference was not observed for ewes on Farm B or Farm C (p>0.5). CONCLUSIONS There were negative associations between ewe CALW pre-lambing, and CALW gain between PD and pre-lambing, and risk of being dry at docking. For all cohorts, heavier ewes and those that gained CALW were less likely to be dry at docking than lighter ewes or those that lost CALW, however these relationships varied between cohorts.

Investigation of fetal loss in ewe lambs in relation to liveweight changes and progesterone concentrations in early to mid gestation.

AIMS: To investigate associations between changes in liveweight and fetal loss in ewe lambs and to determine whether fetal loss was associated with concentrations of progesterone in early and mid-gestation. METHODS: Ewe lambs on two commercial sheep farms (Flock A; n=504 and Flock B; n=460) in the southern North Island of New Zealand were weighed, and body condition score was assessed, prior to breeding and throughout pregnancy. Pregnancy diagnosis was undertaken approximately 56 (PD1), 80 (PD2) and 110 (PD3) days after the start of breeding and fetal loss determined. Blood samples were collected from a cohort of 407 ewe lambs between 45-54 and 73-84 days of gestation. Those that subsequently were diagnosed with fetal loss (n=16) were matched with ewe lambs that maintained pregnancy (n=16), and concentrations of progesterone were measured in the plasma samples from these animals. RESULTS: Fetal loss was diagnosed in 55/472 (11.7%) pregnant ewes from Flock A and 14/378 (3.7%) from Flock B. In both flocks the change in conceptus-free liveweight (CFLW) between PD1 and PD2 differed between ewe lambs with and without fetal loss; in Flock A the mean change was -59.9 (95% CI=-80.1 to -39.7) g/day vs. -3.43 (95% CI=-9.8 to 3.0) g/day (p<0.001), and in Flock B the change was -38.5 (95% CI=-78.9 to 1.94) g/day vs. 79.5 (95% CI=72.6-86.4) g/day (p<0.001). Similarly in Flock A the mean increase in CFLW between PD2 and PD3 was lower in ewe lambs with fetal loss than in those that maintained pregnancy (25.8 (95% CI=-13.8 to 65.4) g/day vs. 181.9 (95% CI=175.1-188.7) g/day) (p<0.001). There was no difference (p>0.05) in early and mid-gestation mean concentrations of progesterone in plasma between ewe lambs that had fetal loss compared with those that maintained pregnancy. CONCLUSIONS: Ewe lambs with fetal loss had a marked reduction in CFLW in the 24-30 days leading up to the identification of the fetal loss compared with those that maintained pregnancy. Early and mid-gestation concentrations of progesterone in plasma were similar between ewe lambs who went on to have fetal loss and those that maintained pregnancy.

The potential interaction between ewe body condition score and nutrition during very late pregnancy and lactation on the performance of twin-bearing ewes and their lambs.

OBJECTIVE: The present study aimed to determine the impact of ewe body condition score (BCS) (over a range of 2.0 to 3.0) and nutritional treatments (consisting of differing herbage masses) during very late pregnancy and lactation and their potential interaction on the performance of twin-bearing ewes and their lambs to weaning. METHODS: On day 142 of pregnancy, twin-bearing ewes with a BCS of 2.0, 2.5, or 3.0 were allocated to a "Moderate' or 'Unrestricted' nutritional treatment until day 95 of lactation (weaning). The nutritional treatments aimed to achieve average herbage masses of 1,200 to 1,300 kg dry matter (DM)/ha (Moderate) and 1,500 to 1,800 kg DM/ha (Unrestricted). RESULTS: There were no three-way interactions between ewe BCS group, nutritional treatment and time for any ewe or lamb parameter. The nutritional treatments had no effect (p>0.05) on lamb birth or weaning weight. Lambs born to Moderate ewes had greater survival and total litter weight at weaning (p<0.05). Regardless of BCS group, Unrestricted treatment ewes had greater body condition and back-fat depth at weaning than Moderate treatment ewes (p<0.05). Ewes of BCS 2.0 group reared lighter lambs to weaning (p<0.05) and tended to have a lower total litter weight (p = 0.06) than BCS 3.0 group ewes. CONCLUSION: This study suggests farmers should aim to have all ewes with a BCS of 2.5 or 3 in late pregnancy for optimal lamb weaning performance. Furthermore, there is no benefit to lamb production of offering ewes pasture masses >1,200 kg DM/ha during very late pregnancy and lactation.

Little appetite for obesity: meta-analysis of the effects of maternal obesogenic diets on offspring food intake and body mass in rodents.

BACKGROUND: There is increasing recognition that maternal effects contribute to variation in individual food intake and metabolism. For example, many experimental studies on model animals have reported the effect of a maternal obesogenic diet during pregnancy on the appetite of offspring. However, the consistency of effects and the causes of variation among studies remain poorly understood. METHODS: After a systematic search for relevant publications, we selected 53 studies on rats and mice for a meta-analysis. We extracted and analysed data on the differences in food intake and body weight between offspring of dams fed obesogenic diets and dams fed standard diets during gestation. We used meta-regression to study predictors of the strength and direction of the effect sizes. RESULTS: We found that experimental offspring tended to eat more than control offspring but this difference was small and not statistically significant (0.198, 95% highest posterior density (HPD)=-0.118-0.627). However, offspring from dams on obesogenic diets were significantly heavier than offspring of control dams (0.591, 95% HPD=0.052-1.056). Meta-regression analysis revealed no significant influences of tested predictor variables (for example, use of choice vs no-choice maternal diet, offspring sex) on differences in offspring appetite. Dietary manipulations that extended into lactation had the largest effect on body weight. Subgroup analysis revealed that high protein to non-protein ratio of the maternal diet may promote increased body weight in experimental offspring in comparison with control offspring; low protein content in the maternal chow can have opposite effect. CONCLUSIONS: Exposure to maternal obesogenic diets in early life is not likely to result in a substantial change in offspring appetite. Nevertheless, we found an effect on offspring body weight, consistent with permanent alterations of offspring metabolism in response to maternal diet. Additionally, it appears that protein content of the obesogenic diet and timing of manipulation modulate the effects on offspring body weight in later life.

Ad libitum Pasture Feeding in Late Pregnancy Does Not Improve the Performance of Twin-bearing Ewes and Their Lambs.

The present study evaluated the effect of controlled ryegrass-white clover herbage availability from day 128 until day 142 of pregnancy in comparison to unrestricted availability, on the performance of twin-bearing ewes of varying body condition score (BCS; 2.0, 2.5, or 3.0) and their lambs. It was hypothesised that under conditions of controlled herbage availability, the performance of lambs born to ewes with a greater BCS would be greater than those born to ewes with a lower BCS. During the period that the nutritional regimens were imposed, the pre- and post-grazing herbage masses of the Control regimen (1,070±69 and 801±30 kg dry matter [DM]/ha) were lower than the ad libitum regimen (1,784±69 and 1,333±33 kg DM/ha; p<0.05). The average herbage masses during lactation were 1,410±31 kg DM/ha. Nutritional regimen had no effect on ewe live weight, BCS and back fat depth or on lamb live weight, indices of colostrum uptake, maximal heat production, total litter weight weaned or survival to weaning (p>0.05). The difference in ewe BCSs and back fats observed among body condition groups was maintained throughout pregnancy (p<0.05). At weaning, ewes from the BCS2.0 group had lower BCS and live weight (2.4±0.2, 74.3±2.6 kg) than both the BCS2.5 (2.6±0.2, 78.6±2.4 kg) and BCS3.0 ewes (2.7±0.2, 79.0±2.6 kg; p<0.05), which did not differ (p>0.05). Ewe BCS group had no effect on lamb live weight at birth or weaning or on maximal heat production (p>0.05). Serum gamma glutamyl transferase concentrations of lambs born to BCS3.0 ewes were higher within 36 hours of birth than lambs born to BCS2.0 ewes and BCS2.5 ewes (51.8±1.9 vs 46.5±1.9 and 45.6±1.9 IU/mL, respectively [p<0.05]). There was, however, no effect of ewe body condition on lamb plasma glucose concentration (p>0.05). Lamb survival was the only lamb parameter that showed an interaction between ewe nutritional regimen and ewe BCS whereby survival of lambs born to BCS2.5 and BCS3.0 ewes differed but only within the Control nutritional regimen ewes (p<0.05). These results indicate farmers can provide twin-bearing ewes with pre- and post-grazing ryegrass-white clover herbage covers of approximately 1,100 and 800 kg DM/ha in late pregnancy, provided that herbage covers are 1400 in lactation, without affecting lamb performance to weaning. The present results also indicate that under these grazing conditions, there is little difference in ewe performance within the BCS range of 2.0 to 3.0 and therefore they do not need to be managed separately.

Identification of reference genes for RT-qPCR in ovine mammary tissue during late pregnancy and lactation and in response to maternal nutritional programming.

The mammary gland is a complex tissue consisting of multiple cell types which, over the lifetime of an animal, go through repeated cycles of development associated with pregnancy, lactation and involution. The mammary gland is also known to be sensitive to maternal programming by environmental stimuli such as nutrition. The molecular basis of these adaptations is of significant interest, but requires robust methods to measure gene expression. Reverse-transcription quantitative PCR (RT-qPCR) is commonly used to measure gene expression, and is currently the method of choice for validating genome-wide expression studies. RT-qPCR requires the selection of reference genes that are stably expressed over physiological states and treatments. In this study we identify suitable reference genes to normalize RT-qPCR data for the ovine mammary gland in two physiological states; late pregnancy and lactation. Biopsies were collected from offspring of ewes that had been subjected to different nutritional paradigms during pregnancy to examine effects of maternal programming on the mammary gland of the offspring. We evaluated eight candidate reference genes and found that two reference genes (PRPF3 and CUL1) are required for normalising RT-qPCR data from pooled RNA samples, but five reference genes are required for analyzing gene expression in individual animals (SENP2, EIF6, MRPL39, ATP1A1, CUL1). Using these stable reference genes, we showed that TET1, a key regulator of DNA methylation, is responsive to maternal programming and physiological state. The identification of these novel reference genes will be of utility to future studies of gene expression in the ovine mammary gland.

Using weather data to predict the presence of Lucilia spp. on sheep farms in New Zealand.

Flystrike remains an important animal health issue on New Zealand sheep farms. To date no useful predictive tool to assist farmers to develop control options has been available. The aim of this study was to use National Institute of Water and Atmospheric Research (NIWA) virtual climate station data in New Zealand to develop a weather-based model to accurately predict the presence of Lucilia spp. on sheep farms throughout New Zealand. Three LuciTrap® baited fly traps were positioned on each of eight sheep farms throughout New Zealand (5 in the North Island and 3 in the South Island). The traps were put out for both the 2018-2019 and 2019-2020 seasons. They were emptied each week and the flies morphologically identified; with the counts of Lucilia cuprina and L. sericata combined as Lucilia spp. The count data for Lucilia spp. for each week of trapping was transformed into a binary outcome and a generalised linear mixed effects models fitted to the data, with farm as a random effect. The dependent variable was Lucilia spp. flies caught, yes or no, and the independent variables were mean weekly climate variables from the nearest NIWA virtual climate station to that farm. The model was trained on the 2018-2019 catch data and tested on the 2019-2020 catch data. A cut point was identified which maximised the model's ability to correctly predict whether Lucilia spp. were present or not for the 2019-2020 catch data, and the sensitivity, specificity, accuracy, and area under the curve (AUC) of the model calculated. The final model included just 3 significant variables, mean weekly 10 cm soil temperature, mean weekly soil moisture index, and mean weekly wind speed at 10 m. Mean weekly 10 cm soil temperature accounted for 64.7% of the variance explained by the model, mean weekly soil moisture index 34.7% and mean weekly wind speed at 10 m only 0.6%. The results showed that the predictive model had a sensitivity of 0.93 (95% CI = 0.80-0.98) and a specificity of 0.75 (95% CI = 0.62-0.85), using a cut point for the probability of Lucilia spp. being present on farm = 0.383. This model provides New Zealand farmers with a tool which will allow them to know when Lucilia spp. flies will likely be present and thus more accurately plan their interventions to prevent flystrike.

Non-targeted analyses of animal plasma: betaine and choline represent the nutritional and metabolic status.

Simple liquid chromatography-mass spectrometry (LC-MS) was applied to non-targeted metabolic analyses to discover new metabolic markers in animal plasma. Principle component analysis (PCA) and partial least squares-discriminate analysis (PLS-DA) were used to analyse LC-MS multivariate data. PCA clearly generated two separate clusters for artificially induced diabetic mice and healthy control mice. PLS-DA of time-course changes in plasma metabolites of chicks after feeding generated three clusters (pre- and immediately after feeding, 0.5-3 h after feeding and 4 h after feeding). Two separate clusters were also generated for plasma metabolites of pregnant Angus heifers with differing live-weight change profiles (gaining or losing). The accompanying PLS-DA loading plot detailed the metabolites that contribute the most to the cluster separation. In each case, the same highly hydrophilic metabolite was strongly correlated to the group separation. The metabolite was identified as betaine by LC-MS/MS. This result indicates that betaine and its metabolic precursor, choline, may be useful biomarkers to evaluate the nutritional and metabolic status of animals.

Effect of early shearing during gestation on the productive and reproductive behavior of female sheep offspring in their first 18 months of age.

The research has shown the interesting contributions of shearing in mid-gestation on the performance of lambs from birth to weaning. Other studies have reported that shearing at early pregnancy influences the development of the placenta and lamb live weight at birth. However, there was a lack of information on the effect of early-prepartum shearing on the behavior of the offspring from weaning onward. This study evaluated the effect of shearing ewes at 50 days of gestation on the growth, reproductive behavior and response to a gastrointestinal parasite challenge in the female offspring from weaning to 18 months old. Fifty-seven Polwarth female lambs were used, 22 being singles and 35 twins born to ewes either shorn at 50 days of pregnancy (PS, n = 23) or shorn at 62 days postpartum (U, control, n = 34) resulting in four subgroups: single lambs born to PS ewes (n = 8), born to U ewes (n = 14), twin lambs born to PS ewes (n = 15) or born to U ewes (n = 20). All progeny were managed together under improved pasture with a minimum forage allowance of 6% live weight on dry basis. Body weight, body condition score and fecal eggs count were recorded every 14 days from weaning to 18 months of age. Concentrations of progesterone were measured weekly (from 4 to 10 months of age and from 14 to 18 months of age) to establish the onset of puberty. Ovulation rate at an induced and a natural heat (545 ± 1.0 and 562 ± 1.0 day old) was recorded. Prepartum shearing did not affect the age at puberty or the ovulation rate of female offspring, but those born as singles were more precocious ( P = 0.03) and heavier ( P = 0.02) at puberty than twin born lambs. Both the average value of parasite egg count ( P = 0.0 7) and the Famacha index ( P = 0.02) for the entire study period were lower in lambs born to prepartum shorn ewes than those born to postpartum shorn ewes. In conclusion, shearing at 50 days of gestation did not affect the growth or the reproductive behavior of female offspring. However, female lambs born from ewe shorn during gestation showed a better response to the parasitic challenge, and further research is required to confirm this.

The effects of birth rank (single or twin) and dam age on the lifetime productive performance of female dual purpose sheep (Ovis aries) offspring in New Zealand.

Greater rates of genetic gain can be achieved by selecting animals born to younger parents. However, little is known about the lifetime performance of dual purpose ewes (Ovis aries) that are born to primiparous ewe lambs (8 to 9 months old at breeding). This experiment investigated the effect of being born from either a ewe lamb or mixed age dam as either a single or twin on the lifetime performance of ewe progeny. Lifetime performance was measured in terms of the life time live weights of the ewes, the weight and number of lambs born and weaned, the efficiency of production (kilograms of lamb weaned / predicted pasture intake (kgDM) of the ewes), and ewe survival. The study followed the lifetime production of 17 single and 41 twin female lambs born to mature ewes (M1 and M2, respectively), and 28 single and 29 twin lambs born to ewe lambs (L1 and L2, respectively). Over their lifetime L2 ewes were lighter (P<0.05) but had similar body condition scores to the other three ewe groups. There was no difference in average progeny weaning weight or total progeny litter weaning weights between groups. The M1 ewes had the greatest longevity (P<0.05) of the four groups. Even though L2 ewes were lighter than the other three groups, this was insufficient to increase their lifetime efficiency of production (kg lamb weaned/predicted pasture consumption), relative to the other groups. These results suggest farmers could select replacements born to ewe lambs without sacrificing animal production.

Induced seasonal reproductive performance in two breeds of sheep.

The objective of the present experiment was to determine whether failure to become pregnant through out-of-season reproductive management regimes is attributable to a failure to stimulate normal corpora lutea (CL) production. Romney ewes and East Friesian Composite (EF) ewes were mated in summer, autumn, winter, and early and late spring after administration of intravaginal progesterone inserts (plus eCG in spring and summer) in a factorial (two breedsxfive mating periods) experimental design. Oestrus rate was determined from mating data, and the numbers of CL were determined by laparoscopy 9 days after ram introduction. Conception rate, pregnancy rate and litter size were determined by transabdominal ultrasonography 62 days after ram introduction. Proportions of ewes displaying oestrus did not differ significantly (75-100%) between seasons or breeds, except for the Romney ewes in summer (67%; P<0.05). Numbers of CL on Day 9 for EF ewes was lowest in autumn (1.5) and winter (1.5), and highest in late spring (2.1; P<0.05). In contrast, Romney ewes had the lowest CL count in summer (1.3), and the highest in autumn (1.8) and winter (1.6; P<0.05). Only in summer was there a difference between breeds (EF 1.8; Romney 1.3; P<0.01). The proportion of ewes that failed to conceive despite having one or more CL present was highest in late spring (EF 41%, Romney 43%), and lowest in autumn (EF 9%, Romney 4%) and winter (EF 14%, Romney 4%; P<0.05). Conception and pregnancy rates followed similar patterns with values for autumn (EF 91%, 91%; Romney 96%, 96%) and June (EF 86%, 82%; Romney 91%, 83%) being significantly (P<0.05) higher than in early (EF 50%, 40%; Romney 54%, 50%) and late spring (EF 44%, 36%; Romney 42%, 36%). Pregnancy rate in summer was higher for EF ewes (60%) than for Romney ewes (39%) but conception rates were not statistically different (EF 68%; Romney 60%). Numbers of foetuses identified at scanning was highest in autumn (1.5) and lowest in late spring (0.5 P<0.001): Litter size in pregnant EF ewes was highest in early spring and lowest in winter (1.8 versus 1.2; P<0.01), but for pregnant Romney ewes was highest in winter and lowest in early spring (1.9 versus 1.3; P<0.001). It was concluded that seasonal differences in the ability of ewes to conceive are not the consequence of failure to display oestrus or to ovulate, but probably are a result of failure of fertilisation or the establishment of pregnancy.

Plasma metabolite concentrations and hepatic enzyme activities in pregnant Romney ewes with restricted feeding.

Plasma metabolite concentrations and activities of enzymes related to energy metabolism in plasma, peripheral leukocytes and liver of pregnant Romney ewes with restricted feeding were measured to assess those metabolites and enzymes as indicators for evaluating metabolic conditions in the ewes. The body weights and plasma lactate concentrations of the low-feeding ewes (about 1.0 times maintenance) were significantly lower than those of the high-feeding ewes (about 1.5 times maintenance). There were no significant differences in plasma protein, glucose, triglyceride, cholesterol, pyruvate and immunoreactive insulin concentrations and plasma and leukocyte enzyme activities between both groups. Hepatic malate dehydrogenase activities were significantly higher and hexokinase activities were significantly lower in the low-feeding ewes than in the high-feeding ewes. Restricted feeding could maintain pregnancy and some plasma metabolites and peripheral leukocyte enzymes may be useful indicators for evaluating metabolic changes in ewes.

Changes in metabolite, energy metabolism related enzyme activities and peripheral blood mononuclear cell (PBMC) populations in beef heifers with two differing liveweight change profiles in New Zealand.

Metabolite and immunoreactive insulin (IRI) concentrations, energy metabolism related enzymes activities and peripheral blood mononuclear cell (PBMC) populations were measured in blood of pregnant Angus heifers with differing liveweight change profiles (gaining or losing), in New Zealand to investigate the meanings of those parameters in the restricted feeding beef heifers. Beef heifers losing liveweight (-412 g/day) showed significantly lower concentrations of plasma IRI, and higher concentrations of plasma free fatty acid (FFA) than heifers gaining liveweight (483 g/day). The cytosolic and mitochondrial malate dehydrogenase (MDH) activities and MDH/lactate dehydrogenase (M/L) ratio in leukocytes of the liveweight losing heifers were significantly higher than those the liveweight gaining heifers. Percentages of cluster of differentiation (CD) 3 positive cells and natural killer (NK) cells in PBMC decreased significantly in the liveweight losing heifers compared to those in the liveweight gaining heifers. Plasma IRI and FFA concentrations, leukocyte cytosolic and mitochondrial MDH activities and CD3 positive and NK cell populations may be useful markers to evaluate metabolic conditions and immunity in the restricted feeding beef heifers.

Can motivations for studying dentistry inform us about gender and BME differences in dental academic careers?

There are various motivators that prompt people to study dentistry but there is evidence that the salience of each varies according to gender and black and minority ethnic (BME) group. Given the current focus on inequality within the science, technology, engineering, medicine and mathematics (STEMM) academic disciplines where dentistry sits, it is important to understand the relevance of different motivators to different social groups if inequality is to be overcome. We carried out a survey of dental students from 11 out of the 18 dental schools in the UK to find out what prompted them to study dentistry. Our findings showed that most people make a personal choice to study dentistry and follow a patient-focused career while the prospect of an academic career was important for less than half of our sample. Differences according to gender and BME group were apparent but did not follow these trends. In order to continue to improve the diversity within dental academia dental schools should consider the different preferences of the workforce and work to broaden its potential.