Breeding Ewes Research Articles

The economic optimum mob size at lambing for triplet-bearing Maternal and Merino ewes across southern Australia

Context Lambing triplet-bearing ewes in smaller mobs significantly increases lamb survival. Aims This paper reports economic analysis to assess the optimum mob size for triplet-bearing ewes during lambing. Methods The analyses considered scenarios for Merino and non-Merino (Maternal) flocks where producers subdivided lambing paddocks using permanent fencing or where ewes were re-allocated within existing paddocks on the basis of pregnancy status. Key results The optimum mob sizes for triplet-bearing ewes during lambing were affected by ewe breed, stocking rate, lamb price and the target return-on-investment if subdividing paddocks. The optimum mob size for triplet-bearing Maternal and Merino ewes was between 27% and 40% of the optimum for twin-bearing ewes and this was similar for scenarios where paddocks were subdivided, or where ewes were re-allocated within existing paddocks. At the standard lamb price of AUD$7/kg carcass weight, the economic return from adjusting the relative mob size of triplet-bearing ewes was AUD$2.05 per multiple-bearing or AUD$14.20 per triplet-bearing Maternal ewe and AUD$0.54 per multiple-bearing ewe or AUD$5.70 per triplet-bearing Merino ewe. Conclusions Overall, these analyses demonstrated that reducing mob size at lambing can be a profitable strategy for improving survival of triplet-born lambs, depending on the current size of lambing mobs. Implications As reported previously for single- and twin-bearing ewes, it is difficult to provide generic recommendations to producers for the optimum mob size of triplet-bearing ewes at lambing because optimum mob size was dependent on several enterprise-specific factors.

CHARACTERIZATION OF THE LACTATION CURVE OF RAMBOUILLET EWES IN MEXICO

Sheep (Ovis aries L.) in Mexico are mainly used for meat production, especially for the Mexican dish known as ‘barbacoa’. There is a growing interest in genetically improving ewe breeds with a focus on milk production for cheese, which is increasing in demand internationally. Among other things, this highlights the importance of understanding the lactation curve (LC) in ewes. The objectives of the present study were: a) to characterize the LC of Rambouillet ewes using Wood’s model (Yt = atb e-ct + εi), estimating its three parameters (a, b, c) and other measures of interest: lactation peak (LP), lactation peak day (DLP), and lactation persistency (PER); b) assess the effects of the number of lambs (NL), the type of lambing (TL), and the weaning time of the offspring (WT) on Wood’s model parameters and those of the LC; and c) estimate phenotypic correlations between Wood’s model and the LC parameters. The results showed that the LC obtained was a ‘typical’ curve with parameters a = 901.2 mL, b = 0.1206, c = -0.01299, LP = 1045.1 mL, DLP = 9.2 d, and PER = 2.1. There were significant effects (p ≤ 0.05) of WT on a and of WT and TL on PER; the highest mean of a (957.4) was obtained with weaning at eight weeks. On the other hand, the largest PER averages were found in single lambs and at six of weeks weaning. Phenotypic correlations (p ≤ 0.05) were estimated between and within Wood’s model and the LC parameters. The results of the present study support the recommendation of a milk production system for Rambouillet ewes to make cheese.

Sex preselection of sheep using mineral solution injection via subcutaneous

The injection on Calcium (Ca) and Magnesium (Mg) solution is regarded as a method that have been conducted for sex preselection in sheep. Therefore, this trail was aimed to examine the effect of macro minerals such CaMg subcutaneous injected to Kurdish breed ewes during pre and post mating on lamb sex ratio skewing toward female. Thirty ewes at cycling multiparous period (based on their age and live weight (LW)) were randomly divided into two groups (15 ewes per group). Weekly (for four weeks) from four weeks’ days pre- to one week post-mating, each ewe (CaMg group) were subcutaneous injected by 30 ml of CaMg solution or sterile water (control group). Ewes live weigh at the end of the study were numerically higher (2.55 kg) in ewes injected with CaMg compared to control group. The serum ca and Mg were higher (P<0.05) in ewes administrated with CaMg solution than those not administrated. The level of total protein, urea, glucose, and cholesterol at blood serum were not affected (P>0.05) by CaMg injection. Reproductive hormone such estrogen was not different between control and injected ewes (P>0.05). Although, progesterone (at CIDR removal period) were increased (P<0.05) in injected ewes than control ewes. The new female born lambs were 2 times higher (P<0.05) in CaMg group compared to control group. The results of current study confirm that increasing the mineral proportion (Ca and Mg) in the ewes around mating via subcutaneous injection could skew sex ratio toward female in sheep. Thus, the findings of this trial might assist farmers in managing their breeding toward female lambs (which are going to be born in fattening enterprises and male milk production). More research is required to test different methods of altering mineral concentration and investigate the link between minerals in the diet and human sex pre-selection.

Stage of lactation, parity, breed, milk composition and minerals affect the non-enzymatic antioxidant activity of sheep milk

The aims of this study were to i) characterize sheep milk for non-enzymatic antioxidant activity via 2 different assays, namely the ferric reducing antioxidant power (FRAP) and the 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), and ii) investigate the effect of milk composition and animal-related parameters on these 2 assays by using Generalized Additive Mixed Model (GAMM) approach. A total of 740 ewes belonging to Massese and Comisana breeds were sampled once during the morning milking across 11 sampling sessions. All milk samples were analyzed for fat, protein, casein, and lactose, somatic cell score (SCS) and minerals (Ca, Mg, Na and Cl). The FRAP and DPPH assays were tested to measure the non-enzymatic antioxidant activity of milk, expressed as μM eq. ascorbic acid/mL of milk and % of inhibition, respectively. The GAMM model included the effect of parity and breed as parametric terms, and the effect of days in milk (DIM), milk yield and the interactions protein × fat, casein × SCS, Ca × Mg and Na × Cl as smooth terms. The sampling day was included in the model as random effect. Results revealed that the non-enzymatic antioxidant capacity of sheep milk, expressed as FRAP, was affected by DIM, potentially because of changes in milk composition over time. Conversely, parity and breed of ewes affected DPPH, suggesting that age- and breed-specific factors are related to specific components in milk acting as hydrogen donors. Milk fat and high casein percentages were found to significantly affect FRAP, while protein content was crucial for high DPPH levels. Additionally, Ca and Mg emerged as important non-enzymatic antioxidants for both FRAP and DPPH, highlighting their important role in antioxidant activity of sheep milk. On the other side, combinations of Na and Cl were particularly influential for FRAP, revealing the complex relationship between these minerals and non-enzymatic antioxidant activity of milk. These findings offer valuable insights into the factors affecting the antioxidative properties of sheep milk, highlighting the need for further exploration of other non-enzymatic antioxidants and their contribution to the total antioxidant activity.

Perinatal behavioral patterns during and after human-animal interactions in rangeland breeding ewes

Perinatal behavioral patterns during and after human-animal interactions in rangeland breeding ewes

Selection and genetic parameters of productivity of sheep (<i>ovis aries</i>) of the Trans-Baikal breed of the Khangil type

The study was conducted to investigate the selection and genetic parameters of productivity of fine-wool sheep of the Trans-Baikal breed of the Khangil typein order to increase the efficiency of the selection process. The relationships between the selected traits (live weight, wool yield) and the exterior and constitutional features were determined using the method of correlation and regression analysis. Of the assessed parameters, the greatest variability was observed for body weight (11.9…19.4 %), wool yield (9.9…11.1 %) and latitudinal linear measurements (8.2…12.4 %). According to the constitution indices, rams differed from ewes by greater leg length, better chest development, stronger skeleton, while ewes were characterized by a more stretched, compact and massive body with a better developed back part. Live weight and wool yield of rams were more closely associated with linear measurements than those of ewes. Live weight of both males and females correlated more strongly with chest girth (respectively +0.916, p 0.001 and +0.740, p 0.001), wool yield – with chest depth in rams (+0.737, p 0.001) and hip width in ewes (+0.469, p 0.001). In Trans-Baikal breed of the Khangil type rams, with an increase in the hip width measurement by 1 cm, it is possible to predict an increase in live weight by 5.50 kg (r = 0.839; p 0.001), in ewes with an increase in chest girth by 1 cm – by 1.04 kg (r = 0.740; p 0.001). The analysis of paired regression equations shows that the live weight of Trans-Baikal breed of the Khangil type ewes is largely determined by the linear measurement of the chest girth: in rams – 83.9 %, in ewes – 54.7 %, the influence of other factors accounts for 16.1 and 45.3 %, respectively. At the same time, in the multivariate regression models, 94.3 and 74.7 % of the change in body weight is explained by the effect of a complex of linear measurements, and the remaining share is attributed to the influence of other factors.

Effect of Different Protocols of Estrus Synchronization on Vaginal Microflora with Antibiotic Susceptibility to Bacteria

To investigate the effect of different protocols for estrus synchronization in ewes on the vaginal tract bacteria and evaluate the sensitivity of bacteria to different antibiotics. Sixteen local breed ewes were allocated to four groups, each containing four. Group A: ewes treated with sponges for 10 days; Group B ewes treated with CIDR for 10 days; Group C ewes treated with sponges for 14 days and finally Group D ewes treated with CIDR for 14 days. Sterile swaps were taken from the vaginaʼs mucous before insertion of sponge or CIDR and after removing it for each group. Vaginal swabs from synchronized ewes were obtained from the vaginaʼs mucous before insertion of sponge or CIDR and after removing it for each group to use in different bacteriological tests. The results showed that the most dominant bacteria were E-Coli 7/7 (100%), and Staphylococcus aureus (71%) before insertion, while in group A, the percentage was 75% and 100% for E-Coli only in group B and group C respectively. According to E-coli, the results showed that it was more sensitive to Doxycycline (3.36±0.3), Enrofloxacin (3.23±0.2), and Ciprofloxacin (3.18±0.3) figure (2). Also, Staphylococcus aureus was sensitive to Doxycycline (3.32±0.4), Enrofloxacin (3.17±0.3), and Ciprofloxacin (3.12±0.3). It was concluded that the E-coli was the most prominent microflora in the vagina in ewes before and after insertion of sponges. Doxycycline, Enrofloxacin, and Ciprofloxacin are the most effective antibiotics against E-coli and Staphylococcus aureus.

Behavioral responses during and after a postpartum human-animal interaction in rangeland breeding ewes

Lamb welfare, performance and survival on rangeland is partially determined by the quality of maternal care received (i.e., high durations of sniffing/grooming, allowing udder access, and staying close to the lamb). Previous studies have explored maternal behavior scores (MBSs), as a tool to select ewes based on their proximity to the lamb and the shepherd, finding variable evidence towards sensitivity and robustness in scores in ability to gauge lamb outcome (birth weight and weaning weight), survival, and maternal care throughout the lambing season. Though this scoring system is convenient, there may be another behavioral attribute related to fear of human or relationship to the human handler may be elicited during lamb collection and processing. This longitudinal study investigated the presence of a trait in response to the human handler employing a Lamb Handling (during processing) and a Lamb Tie Down (after processing) test with N= 42 total ewes and n=26 ewes consistently present across both years of the study. The current study also set out to investigate the relationship between proximity to the shepherd and lamb outcome. Attempts to perform principal component analysis revealed that variables from the Lamb Handling and Lamb Tie down test were not suitable for factor analysis. In the Lamb Handling test, proportion of ‘pacing’ was a nearly significant, negative predictor (P=0.07) term in the binary ‘investigating human’ model, improved model fit and explained more variance compared to the null model [(cumulative weight: 90 vs 10 %); (R2adjusted: 30.8 vs 15.2 %; deviance= 31 vs 18.5 %)]. A random term for individual also improved fit in this model, indicating a potential behavioral trait driven by the ewe related to fear or perception of the human. The occurrence of grazing (0 or 1) was a nearly significant, positive predictor (P=0.06), improved model fit and explained more variance in the ‘investigating human’ model compared to the null model [(cumulative weight: 76 vs 24 %); (R2adjusted: 21 vs 15.2 %; deviance= 26.8 vs 18.5 %)]. Individual did not improve model fit in the relationship between ‘investigation human’ and ‘grazing’. Weaning weights were a nearly significant positive predictor in the model for ‘close proximity’ at lamb collection (P=0.07) and a significant positive predictor for ‘close proximity’ during processing (P<0.001), however, did not improve model fit over the null. Birth weights improved model fit for behaviours including ‘sniffing/grooming’ and ‘pawing’ in the Lamb Tie Down test and these behaviours may have been moderated by maternal investment in heavier lambs. Behavioural responses, expanding beyond proximity measures, can be useful for gauging maternal attachment and investment in the lamb during and after processing. Fear or perception of humans should also be considered as contributors to the response to the shepherd during human-animal interactions in the lambing season.

Breeding Perspective and Analysis of Utility Parameters of the Suffolk Sheep Breed

Abstract Due to insufficient appreciation for the breeding of dairy sheep, breeds of sheep without market milk production have started to gain popularity in Slovakia. Particularly, meat breeds are coming to the forefront, with their breeding being less demanding and more efficient, reflected mainly in the daily weight gains of growing lambs. Study aimed to analyse the utility and reproductive parameters of breeding the meat breeds Suffolk, located in central Slovakia, in the Rimavská Sobota district. Analysis is supplemented by a detailed description of the breed standard and devotes attention to all the tasks carried out on the farm during the sheep farming year. It focuses mainly on a simple year-round grazing system without housing, utilizing only shelters for protection against adverse weather conditions. Analysed utility and reproductive parameters such as average daily gains, loin muscle thickness, backfat thickness, and fertility were compared and evaluated over the last seven years. Results indicate that the evaluated parameters are mainly influenced by the size of the flock, the number of ewes put to ram, the individual approach to each breeding ewe, and environmental factors. Number of offspring is mainly influenced by the nutrition of the dam in the last third of pregnancy. Despite the simplicity of the breeding system, monitored breeding can achieve above-average results with proper management and innovative approaches.

Isolation of Aerobic Bacterial Species Associated with Palpable Udder Defects in Non-Dairy Ewes.

The objectives of these studies were to identify associations between udder half defects (hard or lump) and bacteria isolated from milk or mammary tissue swabs, to compare with samples from normal udder halves at different physiological time points and to compare bacterial species isolated via milk and swabs of mammary tissue from within the same udder halves. A total of 1054 samples were aseptically collected from each udder half of 199 non-dairy breed (Romney) ewes from three different studies (Study A, n = 77; Study B, n = 74; and Study C, n = 48). Conventional bacterial culture and MALDI-ToF mass spectrometry were used for bacterial identification. Of the 225 samples from which bacteria were isolated, Mannheimia haemolytica and Streptococcus uberis were the dominantly identified species from defective udder halves, whereas coagulase-negative staphylococcus (CNS) species, mostly Staphylococcus simulans and Staphylococcus chromogenes, were more frequently isolated from normal udder halves. The ongoing presence of bacterial species over time was variable, although less frequently identified species showed less stability over time. A very high agreement (91.5%) of bacterial species identified was observed between the mammary tissue swab and udder half milk samples during post-weaning. In summary, palpable udder half defects were associated with bacterial positivity, and the ongoing presence of the bacteria over time was dependent on the species involved. Hence, culling ewes with palpable udder half defects that had more stable bacterial species could contribute to reducing the recurrence of palpable defects or mastitis.

Evaluation of enzymatic antioxidant activity and reproductive hormones near and after lambing in pregnant ewes

The current study examined the levels of antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione (GSH), and Malondialdehyde (MDA) and repro ductive hormones (progesterone, estrogen, and cortisol) in pregnant local breed ewes and after lambing in the Basrah governorate. Twenty ewes were used in this study from several fields in the Basrah gov ernorate. Blood sample collection was done in three different periods, pre-lambing, immediately after lambing, and two weeks after lambing. The result showed a significant decrease (p&lt;0.05) in SOD, CAT, and GSH-px activity before and during lambing compared to after lambing. The results also con firmed a significant increase (p&lt;0.05) in the level of GSH pre and during lambing compared to after lambing. While evaluating, the level of MDA revealed a significant increase (p&lt;0.05) in its level dur ing lambing compared to two weeks after lambing. Hormonal analysis showed a significant increase (p&lt;0.05) in the levels of cortisol and estradiol pre and during lambing compared to after lambing, with a significant decrease (p&lt;0.05) in the levels of progesterone after lambing compared to before lambing. This study concluded that during lambing, ewes were under stress factors, and an internal mechanism represented by enzymatic antioxidants like SOD, CAT, and GSH-Px acted actively during this period to neutralize the side effects of stress.

Estimation of the genetic parameters of sheep growth traits based on machine vision acquisition

In the realm of animal phenotyping, manual measurements are frequently utilised. While machine-generated data show potential for enhancing high-throughput breeding, additional research and validation are imperative before incorporating them into genetic evaluation processes. This research presents a method for managing meat sheep and collecting data, utilising the Sheep Data Recorder system for data input and the Sheep Body Size Collector system for image capture. The study aimed to investigate the genetic parameter changes of growth traits in Ujumqin sheep by comparing machine-generated measurements with manual measurements. The dataset consisted of 552 data points from the offspring of 75 breeding rams and 399 breeding ewes. Six distinct random regression models were assessed to pinpoint the most suitable model for estimating genetic parameters linked to growth traits. These models were distinguished based on the inclusion or exclusion of maternal genetic effects, maternal permanent environmental effects, and covariance between maternal and direct genetic effects. Fixed factors such as individual age, individual sex, and ewe age were taken into account in the analysis. The genetic parameters for the yearling growth traits of Ujumqin sheep were calculated using ASReml software. The Akaike information criterion, the Bayesian information criterion, and fivefold cross-validation were employed to identify the optimal model. Research findings indicate that the most accurate models for manually measured data revealed heritability estimates of 0.12 ± 0.15 for BW, 0.05 ± 0.07 for body slanting length, 0.03 ± 0.07 for withers height, 0.15 ± 0.12 for hip height, 0.11 ± 0.11 for chest depth, 0.13 ± 0.13 for shoulder width, and 0.53 ± 0.15 for chest circumference. The optimal models for machine-predicted data showed heritability estimates of 0.1 ± 0.09 for body slanting length, 0.14 ± 0.12 for withers height, 0.55 ± 0.15 for hip height, 0.34 ± 0.15 for chest depth, 0.26 ± 0.15 for shoulder width, and 0.47 ± 0.16 for chest circumference. In manually measured data, genetic correlations ranged from 0.35 to 0.99, while phenotypic correlations ranged from 0.07 to 0.90. In machine data, genetic correlations ranged from −0.05 to 0.99, while phenotypic correlations ranged from 0.03 to 0.84. The results suggest that machine-based estimations may lead to an overestimation of heritability, but this discrepancy does not impact the selection of breeding models.

Varying degrees of human-animal interaction elicit weak evidence of a temporally stable behavioral trait in rangeland breeding ewes.

Coherent patterns of inter-related behaviors that occur across time and contexts, also known as personality or consistent individual differences (CIDs), are important to identify among livestock as they carry valuable information for selective breeding purposes. Repeated testing is necessary to reveal behavioral patterns, yet temporal stability of behavioral traits is often assumed. In this study, three human-animal interaction (HAI) tests were employed within a flock of sheep maintained in the Sierra-Nevada foothills to assess intra-individual consistency and inter- relatedness of behavioral responses. Groups of five (four or six when needed) ewes were placed in three HAI tests (restrained Human Contact, unrestrained Human Presence and unrestrained Human Approach) at the time of post-breeding, gestation and weaning (3 x per year; over 2 years). PCs were created using principal component analysis (PCA) of behaviors from the unrestrained Human Presence test and were compared to the behaviors from the two other HAI tests to evaluate cross-contextual relationships. Frequency of ‘environmental vigilance’ (EV), ‘investigating fence’ (IF) and duration of ‘head down’ (HD) were the only variables to achieve a moderate repeatability estimate [EV: 0.32 ± 0.09, [CI (0.21, 0.48])]; IF: 0.29 ± 0.13, [CI (0.14, 0.48)]; HD: 0.44 ± 0.15, [CI (0.22, 0.68)]. PCA revealed a single component in all Human Presence tests that was characterized by loadings (>0.45) for duration of ‘grazing’ and ‘environmental vigilance’. Spearman’s rank order analysis revealed no significant correlations between PC1 of each replicate. There was also no significant inter-relatedness identified between behaviors of each HAI test. Taken together, it is suggested that the rangeland ewes of this study exhibited consistency of some individual behaviors within the Human Contact and Human Presence test, however, did not demonstrate a temporally stable trait that can be generalized across multiple contexts. Future work should evaluate the influence of extensive versus intensive management styles on the development and maintenance of human-oriented behavioral traits.

Exploratory Study on the Relationship Between Age, Reproductive Stage, Body Condition Score, and Liver Biochemical Profiles in Rembi Breed Ewes

Background: The Rembi sheep breed is renowned for its exceptional meat quality and significant economic profit. Nevertheless, there is a gap in research on the hepatic parameters of this breed in Algeria despite the considerable value of the liver in the Algerian population’s diet. Objectives: The research aimed to determine the impact of physiological factors (age, physiological stage, and body condition score) on biochemical sheep liver parameters. Methods: Sixty clinically healthy female Rembi breed sheep, aged between 3 months and 7 years, raised at the Technical Institute of Livestock (ITELV) Ksar Chellala Farm in Tiaret Province, Algeria, were selected for biochemical analysis and assessing aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), total bilirubin (TBIL), direct bilirubin (DBIL), albumin (ALB), and total protein (TP). Results: The concentrations of AST, ALP, and GGT increased significantly (P≤0.001) in young sheep, while ALT and TP levels decreased (P≤0.05). However, a high level of GGT (P&lt;0.001) was also observed in lactating ewes, and during pregnancy, females have a low level of ALP (P&lt;0.001). Furthermore, the body condition score does not affect any of the measurements. Conclusion: Considering the animal’s age and physiological stage is critical before interpreting the results.

Lipidomic profiling of cervical mucus reveals the potential role of pro-inflammatory derived metabolites on sperm transport across the ovine cervix

Internationally, cervical artificial insemination (AI) in sheep yields low pregnancy rates when frozen-thawed semen is used. An exception to this is in Norway where vaginal AI of frozen-thawed semen to a natural oestrus yields non-return rates in excess of 60%, which has been attributed to the ewe breed used in Norway. This study used both metabolomics and an RNA-sequencing approach to assess the lipid production and composition from cervical mucus and tissue of four European ewe breeds (n = 28–30 ewes per breed) with previously reported differences in pregnancy rates following cervical AI with frozen-thawed semen. These breeds included Suffolk (exhibiting low fertility), Belclare (medium fertility) as well as Norwegian White Sheep and Fur (both with high fertility and pregnancy rates > 60%) at both a synchronised and natural oestrous cycle. The aim was to explore the differences between ewe breeds in the lipidomic profile and to identify candidate biomarkers associated with an optimal environment for cervical sperm transport. The results revealed the identification of 255 lipids, of which 170, 102 and 83 were different between ewe breeds, types of cycle and affected by their interaction, respectively (P < 0.05). Reduced levels of lipids involved in the resolution of inflammation (i.e. 14-HDoHE,17-HDoHE, 15-HETE) were identified in the low-fertility Suffolk breed compared to high-fertility ewe breeds. However, there was an up-regulation of the COX pathway accompanied by increased levels of prostaglandins in the Suffolk breed. These findings indicated a sub-optimal and pro-inflammatory environment that could have a negative effect on cervical sperm transport.

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

BackgroundEwe 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.MethodsFour 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.ResultsIn 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.ConclusionsThis 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.

36 Beyond Environmentally Adapted, Towards Ecologically Purposed: Sheep Production in the Us West

Abstract Consumer demand for sheep products is robust, the annual consumption of U.S. lamb is steadily rising, and the number of U.S. sheep farms is increasing. Nevertheless, the U.S. sheep industry continues to lose market share to foreign competitors and the breeding ewe inventory has declined 30% since 2002. This decline has been more drastic in the upper U.S. Mountain West states, where ewe inventories have declined 37% compared with the national average decline of 26%. This is problematic given the Mountain West generates one-third and one-half of the total U.S. lamb crop and wool revenue, respectively. This depopulation trend indicates obstacles unique to the Mountain West, which are not experienced elsewhere in the nation. Mountain West sheep production systems depend on both private and public rangelands for grazing, which must co-exist with many other goals for public lands, including species conservation and critical wildlife habitat. Extensive conversion of native rangeland to croplands, rural housing, and degraded grasslands has simultaneously resulted in a substantial loss of wildlife habitat, thus creating competing ideologies for how remaining rangelands should be managed. Accordingly, public land management agencies are constantly pressured to change land management plans to accommodate public agendas aimed at restricting or halting livestock grazing on public lands with the assumption wildlife habitat will automatically improve. Such exclusion of grazing from public lands has negatively impacted operational capacity of sheep ranches, thus posing serious threats to the U.S. sheep industry and its contributions towards national food security, rural communities, and rangeland conservation. Therefore, to maintain grazing access to public lands, sheep producers and land managers urgently need tools (e.g., management, genetic) to optimize both conservation and production outcomes synergistically. However, ecological and sheep genetic outcomes have thus far been considered separate rather than integrated goals. Traditional genetic improvements in sheep production are focused strictly on the sheep without regard to the ecological outcome. In other words, the “ecosystem” is only considered to achieve profitable production within that environment. With this in mind, can sheep research move beyond the traditional focus of “environmentally adapted” flocks to “ecologically purposed” flocks? We propose that heritable ecologically focused traits can be identified and used to complement the overall sheep genetic improvement goals of the industry while creating precision-based solutions for sustainable habitat management, such as mitigating catastrophic wildfire risk, halting noxious weed invasion, and shaping vegetative structure of native plant communities towards desirable rangeland and conservation goals. We believe such outcomes extend beyond shaping public opinion about sheep grazing but also towards introducing novel value-based marketable products from the sheep industry.

Defining optimal thresholds for digital Brix refractometry to determine IgG concentration in ewe colostrum and lamb serum in Scottish lowland sheep flocks.

This research aimed to define thresholds for ewe colostrum and lamb serum Brix refractometer measurements in lowland Scottish sheep. This would facilitate the use of this convenient, sheep-side test, enabling quick and accurate identification of poor quality colostrum and prevention of failure of transfer of passive immunity (FTPI) in lambs. Secondary aims were to identify risk factors for poor colostrum quality and FTPI in lambs. Serum samples (n=233) were collected from lambs between 24 and 48hrs after birth, from four lowland Scottish meat sheep farms. Pre-suckle colostrum samples (n=112) were also collected from ewes on two of these farms. Farmers provided information on litter size, ewe body condition score, ewe breed and dystocia. Duplicate digital Brix refractometer measurements were compared with immunoglobulin G (IgG) radial immunodiffusion (RID) testing for all colostrum and serum samples. Receiver operating characteristic (ROC) curves were used to redefine thresholds for Brix testing in colostrum and serum. Linear regression models were constructed with colostrum and serum IgG concentration as the outcomes of interest. Colostrum and serum IgG concentrations were highly variable. The prevalence of inadequate colostrum quality (using <50g/L IgG on RID) was 4.5% (95% CI = 1.5 - 10.1) and the prevalence of FTPI (using <15g/L IgG in serum on RID) was 7.73% (95% CI = 4.64-11.93). A ewe's colostrum IgG concentration was significantly and positively associated with the serum IgG concentration of her lamb(s) (p=0.02). ROC analysis defined a Brix threshold for adequate colostrum quality of >22.10% (sensitivity 80% (95%CI=28.4-99.5), specificity 90% (95%CI=82.3-94.8)). ROC analysis defined a Brix threshold for serum of >8.65% for adequate passive transfer of immunity in Scottish lambs (sensitivity 94% (95%CI=72.7-99.8), specificity 82% (95%CI=76.6-87.2)). To optimise passive transfer of immunity in lambs, we suggest that ewe colostrum Brix measurements be defined as 'poor' (<22%); 'fair' (22-26%) and 'good' (>26%); and lamb serum as 'poor' (<8%); 'fair' (8-9%) and 'good' (>9%). It is recommended that these tests are used as for flock screening, using samples from multiple animals.

Effect of ewe birth litter size and estimation of genetic parameters on ewe reproductive life traits.

Ewe lifetime productivity has economic implications for producers because shorter lifetime productivity results in less profit. Productive years of ewes from extensive, range-based systems of the United States West are generally less than ewes from more temperate regions of the United States. Accordingly, ewes from range-based systems, especially those employing shed-lambing strategies, have been selected for increased litter size to offset decreased lifetime productivity. However, the relationship of the ewe's birth litter size (ELSB) has not been considered a potential contributor to lifetime productivity. Longevity (number of productive years, n=1 per population) and stayability (probability to survive to the next age; ages 2-7years, n=6 per population) were investigated to understand ELSB effects on productive life. Columbia, Polypay, Rambouillet, and Targhee breeds were used in this study. Across-breed (n=11550) and within-breed (Columbia, n=4398; Polypay, n=4534; Rambouillet, n=5922; Targhee, n=6482) analyses were used. Depending on the population, records spanned from 1950 to 2008, where ewe's birth year was included as a fixed effect in the animal model using restricted maximum likelihood estimation procedures. Fixed effects investigated included ELSB (single-, twin-, or triplet-born) and ewe breed (across-breed analyses only). Regardless of trait or population used, heritability ranged from 0.06±0.02 to 0.34±0.03, where stayability at younger ages had the highest estimates. The breed effect was significant in all across-breed analyses (0.0001≤P≤0.038; n=7), where Polypay, a breed selected for accelerated lambing and increased fertility, averaged shorter productive life or had a lower probability of survival to the next age compared with other breeds (longevity: 0.009≤P≤0.223; stayability: 0.000≤P≤0.842). The ELSB was significant in 60% (n=5) and 37% (n=30) of longevity and stayability analyses, respectively. Except for Targhee, all analyses showed ewes born in smaller litter sizes were associated with longer productive lives or higher probability of surviving to the next age, particularly in across-breed analyses (e.g., longevity: single- vs twin-born ewes, P=0.004; vs triplet-born ewes, P=0.003). This study provides evidence that increasing prolificacy in ewes from extensive, range-based production systems may impact productive life. Due to the low heritability of these traits, additional investigation into modeling these traits with dominance effects and litter size needs to be conducted.

Metabolic signature of cervical mucus in ewe breeds with divergent cervical sperm transport: a focus on metabolites involved in amino acid metabolism

IntroductionCervical artificial insemination (AI) with frozen-thawed semen in sheep has yielded unacceptably low pregnancy rates. The exception is in Norway where vaginal AI yields non-return rates in excess of 60%, which has been attributed to the ewe breed used.Objectives and methodsThis study aimed to characterise, for the first time, the ovine follicular phase cervical mucus metabolome, with a focus on the amino acid profile. Cervical mucus was collected from four European ewe breeds with known differences in pregnancy rates following cervical AI with frozen-thawed semen. These were Suffolk (low fertility), Belclare (medium fertility), Norwegian White Sheep (NWS) and Fur (both high fertility).ResultsA total of 689 metabolites were identified in the cervical mucus of all the four ewe breeds. Of these, 458 metabolites were altered by ewe breed, which had the greatest effect in the dataset (P < 0.05). We detected 194 metabolites involved in the amino acid pathway, of which 133, 56 and 63 were affected by ewe breed, type of cycle and their interaction, respectively (P < 0.05). N-methylhydantoin and N-carbamoylsarcosine (degradation products of creatinine pathway) exhibited the greatest fold change decrease in the Suffolk breed compared to Fur and NWS (P < 0.001). Oxidized metabolites were also decreased in Suffolk compared to high fertility breeds (P < 0.05). In contrast, other metabolites such as 3-indoxyl-sulfate, putrescine, cadaverine were significantly increased in Suffolk at the synchronised cycle.ConclusionThe suboptimal amino acid profile in the cervical mucus of the low fertility Suffolk breed may have negative consequences for sperm transport.