Reflections on the causes and the diagnosis of peri-parturient losses of ewes

Variations of blood metabolites in single- and multiple-bearing Ossimi ewes during the transition period

Evaluation of the metabolic profile indices allows early detection and treatment of various metabolic disorders during the transition period in ewes. This study aimed to determine the variations in the blood metabolites around lambing in Ossimi ewes. The blood metabolites were investigated in ewes with single (n = 27) and multiple (n = 9) lambs at 3- and 1-week pre-lambing and 3-week post-lambing. The plasma concentrations of glucose were higher in single-bearing ewes than those in multiple-bearing ewes (p < .05), moreover, its lowest value was measured at 1-week prepartum in both groups. Throughout the study period, the serum concentrations of non-esterified fatty acids (NEFA) were significantly increased in ewes with multiple lambs compared to ewes with single lambs (p < .05), and the highest value was found at 1-week before parturition in both groups. In addition, the serum level of beta-hydroxybutyric acid (BHBA) was higher at 3-week postpartum, and it was significantly increased in multiple-bearing ewes than that in single-bearing ones (p < .05) at 3-week pre-lambing. In both groups, the lowest values of total proteins were determined 1-week before lambing, and its concentrations, at 3- and 1-week prepartum, were higher in ewes with single lambs than those with multiple lambs (p < .05). In contrast, the serum concentrations of albumin were significantly lowered 1-week postpartum (p < .05), and without significant differences between both groups (p > .05). The serum activities of aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT) were significantly increased at 1-week after parturition in both groups (p < .05). Furthermore, the serum activities of AST were higher in multiple-bearing ewes than those in single-bearing ones at 3-week pre-lambing and 3-week post-lambing (p < .05). Variable positive and negative correlations were determined among the blood metabolites. In conclusion, physiological adaptations are associated with the fluctuation of the blood metabolites around lambing. The higher the number of foetuses the higher the metabolic variations in Ossimi ewes. Therefore, regular metabolic profiling for health monitoring may be necessary to avoid disease development during the transition period.

Management of Body Condition Score between Pregnancy Scanning and Lamb Marking Impacts the Survival of Triplet-Bearing Ewes and Their Lambs

This study evaluated the impacts of management of body condition score (BCS) between pregnancy scanning and lamb marking on the mortality of triplet-bearing ewes and their lambs at 19 research sites across Southern Australia. Triplet-bearing ewes of Maternal (crossbred or composite) or Merino breed were randomly allocated to treatment at pregnancy scanning at an average of 97 days from the start of joining: High or Low BCS. The BCS of individual ewes was assessed at pregnancy scanning, pre-lambing (average of 137 days from the start of joining) and marking (average of 165 days from the end of joining), and ewe and lamb mortality to marking, recorded for each mob. The average BCS at pregnancy scanning was 3.4 for Maternal ewes and 3.3 for Merino ewes. There were no breed by BCS treatment effects on the BCS of ewes at pregnancy scanning or lamb marking or on the change in BCS between pregnancy scanning and pre-lambing or between pre-lambing and marking. The change in BCS differed between the High and Low BCS treatments, between pregnancy scanning and pre-lambing (0.12 vs. -0.33; p < 0.001) and between pre-lambing and marking (-0.39 vs. 0.07; p < 0.001) but did not differ between breeds. The average BCS at marking for ewes managed at the High and Low BCS treatments was 3.1 and 3.0 for Maternals and 3.0 and 2.8 for Merinos. Survival of triplet-bearing Merino ewes (p < 0.01) and their lambs (p < 0.001) was greater when ewes were managed at the High BCS compared to the Low BCS. The BCS treatment did not impact the survival of Maternal ewes or their lambs. The survival of Merino but not Maternal lambs was higher when ewes were in greater BCS pre-lambing (p < 0.01) and when ewes gained BCS between pregnancy scanning and pre-lambing (p < 0.01). Ewe mortality was lower when ewes gained BCS between pregnancy scanning and pre-lambing (p < 0.05). Merino ewes were more likely to die than Maternal ewes for a given change in BCS between pregnancy scanning and pre-lambing (p = 0.065). Overall, our findings demonstrate that producers should manage the nutrition of triplet-bearing Merino ewes so that ewes are in greater BCS at lambing and/or to gain BCS between pregnancy scanning and lambing to improve ewe and lamb survival. Triplet-bearing Maternal ewes should be managed to gain BCS between pregnancy scanning and lambing to improve ewe survival.

Reproductive Performance of Triplet-Bearing Ewes on Commercial Farms and Research Priorities Identified by Sheep Producers to Improve the Survival of Triplet-Bearing Ewes and Their Lambs

Consultation with sheep producers was used to quantify the mortality of triplet-bearing ewes and their lambs, identify management practices adopted by producers to reduce these losses and prioritise future research needs to improve the survival of triplet-bearing ewes and their lambs. Surveys were completed by 64 producers across Australia who identified and separated triplet-bearing ewes from twin-bearing ewes in 2017 and/or 2018. On average, 5.9% of all ewes mated were identified as carrying triplets (6.6% of non-Merino ewes and 2.9% of Merino ewes). The average mortality of triplet-bearing ewes was 6.4%, and ewe mortality did not differ significantly between ewe breeds. The average survival of triplet-born lambs was 59%, and survival was significantly higher for lambs from non-Merino compared to Merino ewes (60.1 vs. 52.9%, p < 0.05). The key strategies adopted to reduce the mortality of triplet-bearing ewes and their lambs included management of condition score, feed-on-offer, mob size at lambing and use of shelter. There were no differences (p > 0.05) in the average mortality of triplet-bearing ewes or their lambs between producers that prioritised the adoption of certain management practices. However, significant variation existed between producers in their targets at lambing for ewe condition score (2.8 to 3.5), mob size (10 to 150 ewes) and feed-on-offer (800 to 2500 kg dry matter/ha). Overwhelmingly, the highest priorities for further research identified by producers from surveys, workshops and a webinar were ewe condition score, mob size, feed-on-offer at lambing and mineral supplementation. This study informs benchmarks for mortality of triplet-bearing ewes and their lambs under extensive grazing conditions in Australia, and the priorities for future research to reduce these losses.

The impact of lamb and ewe mortality associated with dystocia on Australian and New Zealand sheep farms: A systematic review, meta-analysis and bio-economic model

Dystocia contributes to lamb and ewe mortality in the periparturient period but impacts for extensive sheep production systems remain poorly understood. Here we show that lamb and ewe mortality associated with dystocia has important impacts on sheep production in Australia and New Zealand, and quantify financial impacts for the Australian sheep industry. A systematic review of the literature identified 11 publications published since 1990 that reported sheep mortality due to dystocia in Australia or New Zealand. Assumptions for ewe breeding flock structure and reproductive performance were based on Australian sheep industry data. The proportion of lamb mortality attributable to dystocia (including stillbirths and perinatal deaths with evidence of hypoxic injury) pooled across all studies (pooled proportional mortality ratio) was 47 % (95 % Confidence Interval (CI): 38, 55). Pooled proportional mortality ratio for Australian studies was 53 % (95 %CI: 47, 60), and for New Zealand studies was 35 % (95 %CI: 19, 51). Pooled proportional mortality ratio was similar for lambs born to Merino and non-Merino ewes, although more data are needed to determine effects of ewe breed independent of other factors. Pooled proportional mortality ratio was higher for single lambs (59 %; 95 % CI: 55, 63) than twin (47 %; 41, 54) or triplet (49 %; 46, 52) lambs. However, the number of dystocia-associated mortalities is higher for twin-born lambs than for singles because total mortality is higher for twin-born lambs. It is estimated that approximately 7.7 million lamb deaths and 297,500 ewe deaths per year are attributable to dystocia in Australia for the national flock of 38 million breeding ewes. The whole-farm bio-economic Model of an Integrated Dryland Agricultural System (MIDAS) was used to determine the impacts of dystocia-associated ewe and lamb mortality on Australian farm profit. Dystocia is estimated to reduce Australian national farm profit by AU$780 million or $23.00 per ewe mated based on an assumed lamb sale price of AU$6.50 per kg carcass weight. These estimates do not include the costs of reduced productivity for surviving ewes and lambs, intervention, post-farmgate impacts, delayed genetic progress, or impacts on animal welfare and access into sheep meat and wool markets. Reducing dystocia through improved genetics and sheep management will improve animal welfare and farm profit.

Mortality of Dairy Sheep during the Peri-Parturient Period: Results of a Field Investigation in Greece

Simple Summary

The paper presents a field investigation into the death of ewes around the peri-parturient (lambing) period. The problem is financially important because, in such cases, the capital (i.e., the ewes) is lost along with the increased expenses incurred by farmers during gestation. The problem was found to occur sporadically. Most cases of death occurred before lambing. Pregnancy toxaemia, an important metabolic disease, was the clinical problem most often associated with peri-parturient death. Factors found to be significantly associated with occurrence of the problem included the average lambing rate, the season of the year during which the lambing period took place, and the number of animals in the flock.

Abstract

Objectives of the study were (a) to investigate the incidence risk of peri-parturient mortality in dairy flocks in Greece, (b) to study when such mortality occurs in relation to lambing, (c) to identify clinical problems associated with the deaths, and (d) to evaluate potentially associated factors. The deaths of ewes during the peri-parturient period (10 days before to 7 days after lambing) were monitored in 60 flocks over two years. In the ewes that died, detailed post-mortems were performed. The incidence risk of peri-parturient deaths was 0.7%. The daily incidence rate of deaths before, at, and after lambing was 0.05, 0.04, and 0.03%, respectively. Clinical problems most frequently associated with peri-parturient deaths were pregnancy toxaemia, ruminal acidosis and post-partum genital problems. For the occurrence of peri-parturient deaths in flocks, the average lambing rate in the flocks was the only significant factor. Regarding deaths before or after lambing, the season during which lambing took place and the number of animals in the flock, respectively, were found to be significant. Most ewes (54.5%) that died at lambing (dystocia) were primigravidae.

Utilising dual-purpose crops in an Australian high-rainfall livestock production system to increase meat and wool production. 2. Production from breeding-ewe flocks

Context The use of dual-purpose crops (for grazing and grain) has increased in the high-rainfall zone in southern Australia. Aim A systems experiment examined the impact on livestock production and supplementary feeding when dual-purpose crops were incorporated into a production system based on Merino ewes producing yearling lambs for sale. Methods The experimental site near Canberra, ACT, was subdivided into nine experimental units (‘farmlets’) with three replicate farmlets for each of three production-system treatments. Each farmlet was managed as a self-contained unit with six Merino ewes and their progeny during 2013–16 (4 years). Ewes were joined in February, lambed in July and shorn in spring; the original cohort of ewes (born 2009) was replaced by a new cohort (born 2012) at the midpoint of the experiment. Six weaners were retained after weaning in each farmlet and sold as yearlings. Control farmlets were sown to pasture based on phalaris (Phalaris aquatica L.) and subterranean clover (Trifolium subterraneum L.) and comprised sub-paddocks to allow rotational grazing. Farmlets in treatments that included dual-purpose crops comprised six sub-paddocks (0.231 ha), with two sown to permanent pasture, and four supporting a rotation of pasture–pasture–dual-purpose canola (Brassica napus L.)–dual-purpose wheat (Triticum aestivum L.). In one of the crop–pasture production system treatments, crop-grazing was prioritised for ewes (ECG treatment); in the other, crop-grazing was prioritised for their progeny weaners (WCG treatment). Key results Greasy fleece weight from ECG (5.3 kg) and WCG (5.1 kg) ewes was higher (P &lt; 0.001) than from control ewes (4.7 kg) averaged over the 4 years. The final sale weight of yearling weaners from the WCG system (44.3 kg) was higher (P &lt; 0.001) than from the control (39.2 kg) or ECG (39.1 kg) systems when averaged over the 4 years. The benefit was predominantly due to greater weight gain during the period when weaners grazed the crop during late autumn and winter. Sale weight of lamb per hectare was higher (P = 0.003) in the WCG treatment (216 kg) compared with the ECG treatment (186 kg) when averaged over the 4 years of the experiment but did not differ (P &gt; 0.05) to the control (201 kg). Meat production over the 4 years was higher (P &lt; 0.001) in the WCG system (226 kg/ha) than other treatments when weight gain from wethers in 2014 was included. The impact of including dual-purpose crops on supplementary feeding was variable and depended on seasonal conditions. Conclusions Incorporation of dual-purpose crops into the high-rainfall production system can increase meat and wool production, with the highest meat production being obtained when crop grazing was prioritised for young carry-over livestock. Implications Prioritising dual-purpose crops for young growing livestock can increase meat production from the system while allowing other livestock classes (wethers or ewes) to graze the crops in better seasons when there was excess forage that would otherwise have been under-utilised.

The effect of parity number on the metabolism, inflammation, and oxidative status of dairy sheep during the transition period

The objective of this study was to evaluate whether dairy sheep during the transition period are affected by their parity numbers with regard to (1) body weight (BW), body condition score (BCS), and production performance (milk yield and composition) and (2) metabolic, inflammation, and stress biomarkers. For this purpose, 30 Sarda dairy ewes [15 primiparous (PRP) and 15 multiparous (MUP) ewes] were recruited on d 90 of gestation. Each group was homogeneous according to age, BW, and BCS. Sampling was carried out at -60, -30, -7, 0, +30, and +60 d from lambing. The MUP ewes showed a higher BW (46.32 vs. 38.71 kg) and larger litter size (1.45 vs. 1.06 kg) but a lower BCS (2.47 vs. 2.70) than the PRP ewes. Furthermore, the MUP ewes had lower concentrations of glucose (3.49 vs. 4.27 mol/L), cholesterol (1.63 vs. 1.81 mmol/L), free fatty acids (0.47 vs. 0.62 mmol/L), and triglycerides (0.22 vs. 0.25 mmol/L) compared with PRP ewes. With regard to inflammation and oxidative stress parameters, the PRP group had higher haptoglobin (0.48 vs. 0.18 g/L) and paraoxonase (187.90 vs. 152.11 U/L) activity than the MUP group. Overall, the MUP ewes were characterized by greater milk production performance and greater feed intake, resulting in a better energy balance, than the PRP ewes. Interestingly, these findings highlighted a different metabolic and inflammatory response over the transition period between PRP and MUP ewes, with the latter displaying lower concentrations of inflammatory-related biomarkers.

Clinical, Ultrasonographic, Bacteriological, Cytological and Histopathological Findings of Uterine Involution in Ewes with Uterine Infection

The objectives of the study were (a) to study the characteristics of uterine involution in ewes that had developed subclinical uterine infection in the immediately post-partum period and (b) to evaluate effects of the infection in the subsequent reproductive performance of ewes. Uterine infection was induced in ewes (I, n = 10) by intrauterine inoculation of Escherichia coli; uninoculated controls were included (C, n = 12). Animals were examined at regular intervals before and post-inoculation. Clinical and ultrasonographic examinations were performed. Vaginal swab samples and biopsy uterine tissue samples were collected for bacteriological, cytological and histological examination. Finally, ewes were put to rams and reproductive performance was monitored. After challenge, it was ultrasonographically found that caruncular dimensions, myometrial thickness and diameter of uterine lumen were greater in I ewes. In these ewes, particular reduction of dimensions occurred during the second week post-partum, whilst in C ewes during the first week. The uterine artery diameter and the blood flow into the uterus were also greater in I than in C ewes. E. coli infection was more frequent and of longer duration in I than in C ewes: in 68.1% and 50.0% of ewes and 19.5 and 14 days, respectively. There was lower proportion of neutrophils and higher of lymphocytes in group I than in C. In inoculated ewes, there was histological evidence of uterine epithelial destruction, increased cellular infiltration, hyperaemia and extracasation, which persisted up to 42 days post-partum. During the subsequent reproductive season, all ewes in group I lambed normally and produced healthy and viable lambs. No significant difference in reproductive performance parameters were seen in I comparison to C ewes. It is concluded that the innate immunity of the uterus sufficed to counteract the bacterial infection, although the process of involution took longer than in healthy animals; moreover, the ultrasonographic examination is a useful means for assessment of the genital tract of ewes post-partum; finally, no adverse effects were noted in the subsequent reproductive performance of ewes.

Do calcium and magnesium deficiencies in reproducing ewes contribute to high lamb mortality?

High lamb mortality continues to be a significant economic and welfare problem within the Australian sheep industry, with 20–30% of lambs born in commercial flocks dying mostly within 3 days of birth. Clinical hypocalcaemia and hypomagnesaemia cause ewe mortality, and, subsequently, either fetal or lamb death, but it is not known whether subclinical deficiencies of calcium (Ca) and magnesium (Mg) compromise lamb survival. This review considers the potential mechanisms through which Ca and Mg deficiencies may influence lamb survival, and factors influencing the risk of deficiency. Pastures grazed by lambing ewes may be marginal in calcium (Ca; &lt;4 g/kg DM) and magnesium (Mg; &lt;0.9 g/kg DM) but also have a high dietary cation–anion difference (&gt;12 meq/100 g DM) and high concentrations of potassium (K; &gt;30 g/kg DM) and nitrogen. In young cereal crops, sodium concentrations are also often low (&lt;0.9 g/kg DM). This combination of minerals and other nutrients creates an imbalance in supply and increases susceptibility to acute Ca (hypocalcaemia) and Mg (hypomagnesaemia) deficiency. Calcium is required for smooth muscle function and has a direct role in uterine contraction, so may influence the duration of parturition. Low Ca and Mg intake both influence insulin release and sensitivity, low Mg results in poor glycaemic control and insulin resistance by impairing both insulin secretion and its action on peripheral tissues, also potentially altering the duration of parturition as well as risk of metabolic disease. Magnesium is also a neuroprotectant that slows the neuronal damage during hypoxia and has been linked with thermogenesis in offspring and increased immunoglobulins in colostrum. These functions indicate potential importance in improving the ease of parturition and improved ability of the newborn lamb to thermoregulate and survive after birth. Subclinical Ca and Mg deficiencies commonly occur in 20% of lambing ewes grazing temperate pastures, so further studies are warranted to investigate whether correction of these deficiencies can improve lamb survival.

Glucose related endocrine and metabolic responses following bolus intravenous hypertonic dextrose administration in Iranian fat-tailed ewes at different pre and post parturition periods

Providing glucose as primary metabolic fuel for maintenance, foetal growth and milk production may be considered necessary for protection against negative energy balance and metabolic disorders. Five adult Ghezel ewes were selected 4 weeks before their parturition and followed at 2 weeks before, 2 and 4 weeks and 2, 3 and 4 months after parturition. Dextrose 50% was administered at 500 mg/kg, 10 mL/kg/hour, and blood samples were collected from all ewes prior to and 1, 2, 3 and 4 hours after 50% dextrose infusion. Serum levels of glucose, beta-hydroxybutyric acid, non-esterified fatty acids, cholesterol, triglyceride, high, low and very low density lipoproteins, insulin, triiodothyronine, thyroxine, prolactin, cortisol and insulin like growth factor-1 were evaluated. Glucose and insulin were increased significantly and immediately following intravenous dextrose administration at all studied periods. The levels of beta-hydroxybutyric acid and non-esterified fatty acids were significantly decreased following dextrose infusion at all periods. Triiodothyronine was decreased in pregnant ewes and increased in non-pregnant, lactating ones. The significant increasing cortisol patterns were detected at 2 and 4 weeks before and 2 and 4 weeks after parturition following dextrose administrations. The decreasing patterns of insulin like growth factor-1 were seen in all studied periods. Prolactin was significantly increased following dextrose administration at 4 and 2 weeks before and 2 weeks after parturition. Bolus intravenous hypertonic dextrose administration could induce the obvious endocrine and metabolic responses in Ghezel ewes via providing a source of energy and the glucose is an important direct controller of metabolic interactions in Ghezel ewes.

Use of bootstrapped, regularised regression to identify factors associated with lamb-derived revenue on commercial sheep farms

The profitability of UK sheep farms is variable with many farms making a net loss. For economic sustainability, farms have to be profitable, therefore it is important to maximise income whilst controlling costs. The most important source of income in sheep flocks is from lamb production but there is little information on factors that explain variability between farms in revenue from lamb sales. The aim of this research was to identify farm, farmer and management factors likely to have the largest, most reliable associations with lamb-derived revenue. From a population of 830 sheep farms, 408 farmers completed an online questionnaire comprising over 300 variables. Total lamb-derived revenue was calculated for each farm using abattoir information including carcass classification. The median flock size was 560 ewes, median land size 265 acres, median revenue per acre from lambs sold was £197 (IQR = 120-296) and median revenue per ewe £95 (IQR = 72-123). A robust analytic approach using regularised (elastic net) regression with bootstrapping was implemented to account for multicollinearity in the data and to reduce the likelihood of model over-fitting. To provide model inference and allow ranking of variables in terms of relevance, covariate stability and coefficient distributions were evaluated. Factors with high stability and relatively large positive associations with revenue per acre were (median effect size (£); 95 % bootstrap probability interval); an increased stocking rate of 0.2 ewe/acre (13; 6-17), fertilizer being used on most of the grazing land (18; 0.1-37), the use of rotational grazing (13; 0.3-34), decreased proportion of ewes with prolapses (4; 0.3-9), separation of lame sheep from the rest of the flock (16; 0.9-37), selecting ewes for culling based on prolapses (20; 0.2-55) and infertility (20; 2-46), conducting body condition scoring of ewes at lambing (28; 3-58), early lactation (21; 1-54) or weaning (25; 2-70), increased farmer education (20; 2-54) and farmers with a positive business attitude (15; 0.2-38). Additional factors with a high stability and relatively large associations with increased revenue per ewe were; never trimming diseased feet of lame ewes (9; 0.8-22) and making use of farm records (5; 0.3-12). This is the first study in animal health epidemiology to use bootstrapped regularised regression to evaluate a wide dataset to provide a ranking of the importance of explanatory covariates. We conclude that the relatively small set of variables identified, with a potentially large influence on lamb-derived revenue, should be considered prime candidates for future intervention studies.

Evaluation of the Nova Vet Meter for sheep-side monitoring of β-hydroxybutyric acid (BHBA) and description of ewe BHBA during late gestation in three flocks from the Northeastern U.S

Prevention of metabolic diseases in small ruminants may improve production efficiency and profitability, yet ewes carrying multiples or who are in poor body condition are at increased susceptibility to develop ketosis. This study evaluated the hand-held Nova Vet Meter to accurately detect β-hydroxybutyric acid (BHBA) concentrations in ewes and determined the percentage of ewes at moderate (0.8 to 1.5 mmol/L BHBA) and greatest (≥1.6 mmol/L BHBA) risk to develop ketosis during late gestation. To validate the Nova Vet Meter, BHBA concentrations of 104 paired blood samples were measured using the Nova Vet Meter and gold-standard laboratory analysis. Receiver operating characteristics were calculated. The accuracy and sensitivity of detecting BHBA concentrations at 0.8 to 1.5 mmol/L were 94.2% and 97.3%, respectively. The accuracy and sensitivity of detecting BHBA concentrations ≥ 1.6 mmol/L were 98.0% and 50.0%, respectively. Ewe body weight (BW), body condition score (BCS), and BHBA of 117 ewes from three flocks were determined weekly during the four weeks before parturition. During the last three weeks of gestation >20% of ewes were identified with moderate risk to develop ketosis. During the last four weeks of gestation, ewes carrying triplets had reduced BCS (P = 0.0002) and increased BHBA concentrations (P < 0.0001) compared with singleton and twin pregnancies. Ewe BHBA did not correlate with lamb birth weight (R² = 0.003; P = 0.41). In conclusion, the Nova Vet Meter is suitable for sheep-side BHBA monitoring between 0.8 and 1.5 mmol/L, but further testing is necessary to evaluate BHBA readings ≥1.6 mmol/L.

The association of serum β-hydroxybutyrate concentration with fetal number and health indicators in late-gestation ewes in commercial meat flocks in Prince Edward Island

Late-gestation ewes are susceptible to ketonemia resulting from high energy requirement for fetal growth during the last few weeks of pregnancy. High lamb mortality is a possible consequence of effects of ketonemia on both ewes and lambs. Determining risk factors to ketonemia is a fundamental step to identify ewes at risk, in order to avoid losses caused by ketonemia. Serum β-hydroxybutyrate (BHBA) concentrations of 384 late-gestation ewe samples were determined. Physical examinations, including body condition, FAMACHA^© and hygiene scoring, were performed. Udders and teeth were also examined. Fecal floatation was performed to detect gastrointestinal helminth eggs of the ewe fecal samples. General feeding management practices and season at sampling were recorded. Litter sizes were retrieved from lambing records. Factors associated with log serum BHBA concentration were determined using a linear mixed model, with flock and lambing groups as random effects. The mean serum BHBA concentration was 545.8 (±453.3) μmol/l. Ewes with a body condition score (BCS) of 2.5-3.5 had significantly lower log BHBA concentrations than ewes with a BCS of ≤2.0, by 19.7% (p = 0.035). Ewes with a BCS of >3.5 had a trend toward higher log BHBA concentrations compared to ewes with a BCS of 2.5-3.5. Ewes with a FAMACHA^© score of 3 had significantly higher log BHBA concentrations than ewes with a FAMACHA^© score of 1 or 2, by 12.1% (p = 0.049). Ewes in which gastrointestinal helminth eggs were detected had significantly higher log BHBA concentrations than ewes in which helminth eggs were not detected, by 12.3% (p = 0.040). An increased litter size was associated with higher log BHBA concentration (p ≤ 0.003), with the log BHBA concentrations of ewes having twins, triplets, and quadruplets or quintuplets were higher than those of ewes having singleton by 19.2%, 30.4%, and 85.2%, respectively. Season at sampling confounded the association between log BHBA concentration and FAMACHA^© score, and therefore was retained in the final model even though it was not statistically significant. Intra-class correlation coefficients at the flock and lambing group levels were 0.14 and 0.32, respectively.

RNA interference-based technology: what role in animal agriculture?

Animal agriculture faces a broad array of challenges, ranging from disease threats to adverse environmental conditions, while attempting to increase productivity using fewer resources. RNA interference (RNAi) is a biological phenomenon with the potential to provide novel solutions to some of these challenges. Discovered just 20 years ago, the mechanisms underlying RNAi are now well described in plants and animals. Intracellular double-stranded RNA triggers a conserved response that leads to cleavage and degradation of complementary mRNA strands, thereby preventing production of the corresponding protein product. RNAi can be naturally induced by expression of endogenous microRNA, which are critical in the regulation of protein synthesis, providing a mechanism for rapid adaptation of physiological function. This endogenous pathway can be co-opted for targeted RNAi either through delivery of exogenous small interfering RNA (siRNA) into target cells or by transgenic expression of short hairpin RNA (shRNA). Potentially valuable RNAi targets for livestock include endogenous genes such as developmental regulators, transcripts involved in adaptations to new physiological states, immune response mediators, and also exogenous genes such as those encoded by viruses. RNAi approaches have shown promise in cell culture and rodent models as well as some livestock studies, but technical and market barriers still need to be addressed before commercial applications of RNAi in animal agriculture can be realised. Key challenges for exogenous delivery of siRNA include appropriate formulation for physical delivery, internal transport and eventual cellular uptake of the siRNA; additionally, rigorous safety and residue studies in target species will be necessary for siRNA delivery nanoparticles currently under evaluation. However, genomic incorporation of shRNA can overcome these issues, but optimal promoters to drive shRNA expression are needed, and genetic engineering may attract more resistance from consumers than the use of exogenous siRNA. Despite these hurdles, the convergence of greater understanding of RNAi mechanisms, detailed descriptions of regulatory processes in animal development and disease, and breakthroughs in synthetic chemistry and genome engineering has created exciting possibilities for using RNAi to enhance the sustainability of animal agriculture.

Ultrasonographic findings in the ovine udder during lactogenesis in healthy ewes or ewes with pregnancy toxaemia

Objective of the study was to record, by means of ultrasonographic examination, changes occurring during lactogenesis in the udder of healthy ewes and of ewes with pregnancy toxaemia. The work was carried out in 28 ewes, 16 with pregnancy toxaemia (group A) and 12 healthy controls (group B). B-mode and Doppler ultrasonographic examination of the udder of ewes was performed. During the last month of pregnancy, grey-scale intensity values of mammary parenchyma in group A were significantly greater than in group B (P = 0.007), as was also the progressive increase in grey-scale intensity values in both groups (P < 0.001). Blood mammary input was significantly greater in ewes of group B than in ewes of group A (P < 0.05), as was also the progressive increase in blood input in both groups (P < 0.001). Further, differences between the two groups were identified in pulsatility index (P = 0.007) and in mean blood velocity (P = 0.036), but only during the last fortnight of pregnancy. After lambing, grey-scale values decreased sharply compared to those in pregnancy (P < 0.01), whilst blood input, pulsatility index and mean blood velocity continued the same trend as at the last stage of pregnancy, with differences between the two groups still prevalent (P < 0.05). There was a reverse correlation between grey-scale intensity values and milk quantities (P < 0.035) and a correlation between blood input and milk quantities (P < 0.07). The progressive increase in the diameter of the external pudendal artery was significant (P < 0.001), but no significant differences were evident between the two groups (P > 0.35). Differences between group A and group B in all other haemodynamic parameters studied were not significant, neither throughout the last month of pregnancy (P > 0.25), nor during the first week of lactation (P > 0.06). However, their progressive changes during the last month of pregnancy were significant (P < 0.02).

Evaluation of 2 electronic handheld devices for diagnosis of ketonemia and glycemia in dairy goats

The objective of this study was to evaluate the suitability of the electronic handheld devices FreeStyle Precision (FSP; Abbott Germany, Wiesbaden, Germany) and GlucoMen LX Plus (GML; A. Menarini GmbH, Vienna, Austria) for the measurement of β-hydroxybutyrate (BHBA) in whole blood in dairy goats. Additionally, glucose concentration was analyzed with the FSP device. For method comparison, the samples were also analyzed in the laboratory by standard methods, which served as the gold standard in our study. A further objective was to evaluate the agreement between samples obtained by minimal invasive venipuncture of an ear vein and measurements of whole blood samples from the jugular vein (vena jugularis). In total, 173 blood sample pairs collected from 28 goats were obtained from an ear vein and from the jugular vein. The Spearman correlation coefficients (rsp) for BHBA concentrations determined with the FSP or GML and the gold standard were 0.95 and 0.85 for the ear vein and 0.98 and 0.88 for the jugular vein, respectively. Bland-Altman plots of differences showed a positive bias of 0.12 (ear vein) and 0.21 (jugular vein) when determination was performed with the FSP and a negative bias of 0.21 (ear vein) and 0.24 (jugular vein) when using the GML. For the FSP, applying the adjusted thresholds determined by ROC analysis of 0.9 (ear vein) and 1.0 mmol/L (jugular vein) allowed to distinguish between healthy goats and animals with hyperketonemia with sensitivities (Se) and specificities (Sp) for samples from the ear vein of 0.98 and 0.85, and from the jugular vein of 0.99 and 0.94, respectively. For the GML, adjusted thresholds were 0.5 mmol/L for the ear vein (Se=0.94, Sp=0.75) and 0.6 mmol/L for the jugular vein (Se=0.88, Sp=0.91). Repeated analyses of defined whole blood samples showed average inter- and intraassay coefficients of variation of 6.6 and 7.3% for FSP, and of 35.6 and 35.4% for GML, respectively. Test characteristics for determining glucose concentration with the FSP compared with the gold standard were poor (ear vein: rsp=0.41; jugular vein: rsp=0.51), with low validity to distinguish between hypo- and normoglycemia (Se=0.71, Sp=0.66). The present study showed good test characteristics for the FSP and moderate for the GML device for determining BHBA concentrations in whole blood. Additionally the results demonstrate the suitability of testing BHBA concentration in a blood drop obtained from an ear vein. Based on the results of this study, the FSP device is not suitable to differentiate normo- from hypoglycemia in goats.

Trematode infections in pregnant ewes can predispose to mastitis during the subsequent lactation period

Objective was to investigate if trematode infections predispose ewes to mastitis and/or metritis. We used 80 trematode-infected ewes: primigravidae in group P-A and multigravidae in M-A remained untreated, primigravidae in P-B and multigravidae in M-B were drenched with netobimin and multigravidae in M-C were given rafoxanide. We collected faecal samples for parasitological examination, blood samples for β-hydroxybutyrate concentration measurement and uterine content, teat duct material and milk samples for bacteriological examination. We found significant differences in blood β-hydroxybutyrate concentrations between M-A, M-B and M-C during pregnancy (P ⩽ 0.002). We did not observe significant differences between groups regarding development of metritis (P>0.83). We found that for M-A, M-B and M-C ewes, respectively, median time to first case of mastitis was 5.75, 21 and 6.75 days after lambing (P = 0.003) and incidence risk of mastitis was 0.308, 0.069 and 0.222 (P = 0.047). We postulate that trematode infections predispose ewes to mastitis; perhaps, increased β-hydroxybutyrate blood concentrations adversely affect mammary cellular defences. This is the first report associating parasitic infections with mastitis in sheep.

Scientific Opinion on the public health hazards to be covered by inspection of meat from sheep and goats

A risk ranking process identified Toxoplasma gondii and pathogenic verocytotoxin-producing Escherichia coli (VTEC) as the most relevant biological hazards for meat inspection of sheep and goats. As these are not detected by traditional meat inspection, a meat safety assurance system using risk-based interventions was proposed. Further studies are required on T. gondii and pathogenic VTEC. If new information confirms these hazards as a high risk to public health from meat from sheep or goats, setting targets at carcass level should be considered. Other elements of the system are risk-categorisation of flocks/herds based on improved Food Chain Information (FCI), classification of abattoirs according to their capability to reduce faecal contamination, and use of improved process hygiene criteria. It is proposed to omit palpation and incision from post-mortem inspection in animals subjected to routine slaughter. For chemical hazards, dioxins and dioxin-like polychlorinated biphenyls were ranked as being of high potential concern. Monitoring programmes for chemical hazards should be more flexible and based on the risk of occurrence, taking into account FCI, which should be expanded to reflect the extensive production systems used, and the ranking of chemical substances, which should be regularly updated and include new hazards. Control programmes across the food chain, national residue control plans, feed control and monitoring of environmental contaminants should be better integrated. Meat inspection is a valuable tool for surveillance and monitoring of animal health and welfare conditions. Omission of palpation and incision would reduce detection effectiveness for tuberculosis and fasciolosis at animal level. Surveillance of tuberculosis at the slaughterhouse in small ruminants should be improved and encouraged, as this is in practice the only surveillance system available. Extended use of FCI could compensate for some, but not all, the information on animal health and welfare lost if only visual post-mortem inspection is applied.

Factors involved in high ewe losses in winter lambing flocks grazing dual-purpose wheat in southern New South Wales: a producer survey

A comparative survey was undertaken with 43 sheep producers in southern New South Wales using a semi-structured interview to investigate factors associated with high ewe mortality rates in winter lambing flocks grazing dual-purpose wheat. Participants were classified as either control (n = 23), who had not observed abnormally high ewe deaths, or case (n = 20), who had observed abnormally high ewe mortality rates when sheep grazed dual-purpose wheat. Ewe losses associated with grazing wheat were higher in the case group compared with the control group (8.6 vs 1.8%; P < 0.001) and there was also more deaths attributed to metabolic disease (3.4 vs 0.6%; P < 0.05). A higher proportion of control respondents had provided magnesium or sodium supplementation to ewes grazing wheat (P < 0.05). The body condition score of ewes entering the grazing period was significantly higher in the control group (3.2 vs 2.8; P < 0.05). The proportion of respondents who fed roughage to ewes grazing wheat did not differ significantly between control and case groups (48 vs 35%). A higher proportion of respondents in the case group had supplied grain to ewes (25 vs 0%; P < 0.05), which may have been associated with the lower body condition of sheep in these flocks compared with the control group. It was concluded that supplying ad libitum access to mineral supplements that include magnesium, sodium and possibly calcium, and maintaining adequate body condition score can reduce the risk of high ewe mortality rates when reproducing ewes graze dual-purpose wheat.

Health management of ewes during pregnancy

The objectives of health management of ewes during pregnancy are as follows: (i) successful completion of pregnancy at term, (ii) birth of healthy and viable lambs, with optimal birth and potential weaning bodyweight, (iii) optimum milk production during the subsequent lactation and (iv) improved management in relation to drug residues in animal products. Knowledge of the physiological background of pregnancy in ewes: changes, mechanisms and interactions, during pregnancy is important for the overall health management of ewes during pregnancy. Health management of pregnant ewes includes diagnosis of pregnancy and evaluation of the number of foetuses borne, which will support strategies for subsequent management of the flock. Nutritional management of ewes depends upon the stage of lactation and specifically aims to (i) prevention of pregnancy toxaemia and other metabolic diseases during the peri-partum period, (ii) formation of colostrum in appropriate quantity and quality, (iii) production of lambs with normal future birth bodyweight and (iv) support of increased milk yield during the subsequent lactation. At the end of lactation, udder management of pregnant ewes includes its clinical examination, culling of ewes considered unsuitable for lactation and, possibly, the intramammary administration of antibiotics; objectives of that procedure are (i) to cure infections which have occurred during the previous lactation and (ii) to prevent development of new mammary infection during the dry period. Management of abortions includes the correct and timely diagnosis of the causative agent of the disorder, as well as the strategic administrations of chemotherapeutic agents, aiming to prevent abortions in flocks with confirmed infection with an abortifacient agent, especially if no appropriate vaccinations had been carried out before the mating season. During the final stage of pregnancy, health management of ewes includes administration of appropriate anthelmintic drugs, aiming to eliminate gastrointestinal helminthes (thus, increasing production output of ewes) and preventing the built-up of parasitic burdens in the environment (thus, reducing infection of lambs during their neonatal period). Vaccinations of pregnant ewes aim to protect these animals, as well as their offspring, especially against diseases which are a frequent cause of neonatal mortality (e.g., clostridial infections). Health management also aims to prevent the main metabolic disorders of pregnant ewes (i.e., pregnancy toxaemia and hypocalcaemia), as well as to monitor flocks for development of these disorders. Health management of pregnant ewes is completed with application of husbandry practices before the start of the lambing season. Finally, in some cases, health management may include induction and synchronisation of lambings, which is a management or therapeutic procedure.