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Background: Neonatal mortality is a significant multifactorial problem that affects flock productivity. Different infectious and non-infectious factors have been attributed to lamb losses. The objective of the present study was to identify the major causes of neonatal mortality. Methods: In a 3-months period, 114 Lacaune breed lambs died of which 52 animals were lost with clinical signs of infection. Heart and lung samples were collected and transmitted to the laboratory. Microbiological cultures following biochemical tests were conducted to identify bacterial infection of the lambs. Results: A total of 52 out of 114 lambs (45.6%) were infected with bacteria. The bacteria including Escherichia coli (30.8%), Proteus mirabilis (19.2%), Pasteurella multocida (1.5%), Corynebacterium pseudotuberculosis (7.7%), Mannheimia haemolytica (3.9%), Staphylococcus epidermidis (1.9%) were isolated. The role of the identified pathogens was more significant in lamb death compared to noninfection causes. Diarrhea was the most euoitcefni disease followed by septicemia and pneumonia. Escherichia coli was isolated significantly more than other bacterial agents (30.8%). Conclusion: The present findings showed Escherichia coli as the most common pathogen leading to lamb losses in the first two weeks of life. ciieigyeiuet practice which encompasses both environment and milking equipment, periodical flaming, and providing dry and clean bedding can dramatically decrease the infection among uiobfeu animals. Reduction of the birth density and avoiding synchronization until the expert and labor capacity has reached the optimal level are necessary actions to reduce infectious diseases. [ABSTRACT FROM AUTHOR]

Background: Neonatal mortality is a significant multifactorial problem that affects flock productivity. Different infectious and non-infectious factors have been attributed to lamb losses. The objective of the present study was to identify the major causes of neonatal mortality. Methods: In a 3-months period, 114 Lacaune breed lambs died of which 52 animals were lost with clinical signs of infection. Heart and lung samples were collected and transmitted to the laboratory. Microbiological cultures following biochemical tests were conducted to identify bacterial infection of the lambs. Results: A total of 52 out of 114 lambs (45.6%) were infected with bacteria. The bacteria including Escherichia coli (30.8%), Proteus mirabilis (19.2%), Pasteurella multocida (1.5%), Corynebacterium pseudotuberculosis (7.7%), Mannheimia haemolytica (3.9%), Staphylococcus epidermidis (1.9%) were isolated. The role of the identified pathogens was more significant in lamb death compared to non-infection causes. Diarrhea was the most infectious disease followed by septicemia and pneumonia. Escherichia coli was isolated significantly more than other bacterial agents (30.8%). Conclusion: The present findings showed Escherichia coli as the most common pathogen leading to lamb losses in the first two weeks of life. The hygienic practice which encompasses both environment and milking equipment, periodical flaming, and providing dry and clean bedding can dramatically decrease the infection among newborn animals. Reduction of the birth density and avoiding synchronization until the expert and labor capacity has reached the optimal level are necessary actions to reduce infectious diseases.

Sheep are important for food and livelihood security in sub-Saharan Africa, and maximizing lamb weight gain while minimizing mortality is essential to improve production. Using the Menz sheep breeding villages of Amhara region in Ethiopia as a case study, the weight gain and mortality rate of 208 lambs were monitored during their first 5 months of life. The study was conducted in intervention and control villages, where the intervention villages were part of community-based breeding programmes and had participated in various projects aiming to improve sheep production and management. Multivariable linear regression analysis was conducted to detect associations between weight gain from birth to 1 month, and birth to 5 months, and different lamb and ewe characteristics, farmer education, application of management routines, and presence of village level sheep management interventions. In general, lambs from intervention villages, without certain signs of diseases, whose mothers were 2 years or older, had a body condition score of more than 2 on a 5-point scale, and who originated from flocks where disease prevention strategies had been implemented, had gained more weight. Overall lamb mortality was 6.8% with most deaths occurring before 1 month of age. This study highlights that health interventions in ewes improve lamb survival and weight gain and that the care of lambs during the first month of life is crucial for overall herd productivity. [ABSTRACT FROM AUTHOR]

Context: Proven strategies to address lamb mortality include pregnancy scanning and the differential management of single- and twin-bearing ewes. However, current adoption rates of this best-practice management by Australian producers remain low at ~20%. Aims: We explored producer perceptions about lamb mortality and the adoption of pregnancy scanning, and analysed whether producer characteristics, demographics, beliefs or management practices have an influence on perceptions towards pregnancy scanning or lamb survival. Methods: Data were collected through an on-line self-administered survey of lamb producers in New South Wales, Australia. Descriptive and inferential statistics were used to summarise the data and test for interdependence of variables. Key results: The survey results revealed that New South Wales sheep producers have low participation rates in extension programs and low engagement in record-keeping practices. Only 4% of respondents considered current lamb mortality rates acceptable and the majority agreed that lamb mortality poses a threat to Australia's sheep industry. Findings identified numerous significant relationships between producer characteristics, demographics, beliefs, management practices, non-participation in extension programs, and perceptions towards pregnancy scanning, lamb mortality and sheep welfare. Survey participants were more likely to have adopted pregnancy scanning if they had participated in extension programs. Conclusions: Further extension efforts should be focused on producers who have not adopted any record-keeping practices or previously participated in extension programs. Extension should be tailored to different enterprises, owing to the influence of enterprise focus on beliefs, while also considering producer demographics. Implications: A strong case exists for continued investment in future marketing, education, and research, development and extension to increase the capacity of Australia's sheep industry and, in particular, to increase the adoption of pregnancy scanning. Negative consumer perceptions of animal welfare associated with high lamb mortality rates pose a threat to Australia's sheep industry. Strategies to address lamb mortality include pregnancy scanning; however, current adoption rates by Australian producers are low. Key results related to producers' beliefs towards lamb survival revealed that non-participation in extension programs is a significant barrier to the adoption of pregnancy scanning, and a strong case exists for continued investment in future extension tailored to different types of sheep enterprises. [ABSTRACT FROM AUTHOR]

According to previous studies, lamb mortality is high in the Ethiopian highlands. The present study aims to evaluate the execution of preventive sheep herd health management practices with respect to if, and how, such practices are linked to occurrence of lamb mortality. Interviews were performed with 74 sheep-owning households participating in a capacity development program on livestock and 69 households not participating in such program. To evaluate the impact of combinations of performed practices, a scoring system was developed—the households retrieved a higher score the more desired routines were accomplished. To identify which practices had the highest impact on lamb mortality, a similar score was calculated for each phase of the sheep reproductive year, creating sub-scores for each phase. The results showed a significant (p < 0.05) negative correlation between the total number of performed practices and occurrence of lamb mortality, indicating a lower occurrence of lamb mortality the more desired practices implemented. Further analysis of sub-scores showed significant (p < 0.05) negative correlations between a higher number of performed desired practices during gestation period and during lambing. Conclusively, the study indicates that preventive herd management routines are beneficial for lamb survival, foremost when enforced during the gestation period and around lambing—hence, this is where to focus future interventions. [ABSTRACT FROM AUTHOR]

Abstract Background Toxoplasma gondii causes reproductive losses in sheep worldwide, including Australia. The reproductive performance of primiparous ewes is typically lower than for mature, multiparous ewes, and younger ewes are more likely to be immunologically naïve and therefore more susceptible to reproductive disease if T. gondii infection occurs during pregnancy. The aim of this study was to assess the impact of infection with T. gondii on the reproductive performance of primiparous ewes in southern Australia using a prospective cohort study. This will inform the need for targeted control strategies for T. gondii in Australian sheep. Results Toxoplasma gondii seropositivity using indirect ELISA was detected at 16/28 farms located across southern Australia. Apparent seropositivity to T. gondii was lower in primiparous ewes (1.1, 95% confidence interval (CI) 0.6, 1.8) compared to mature, multiparous ewes (8.1, 95% CI 6.0, 10.5; P

Background: There is a high lamb mortality rate during the first three days of life, resulting in sheep flock economic losses and neonate welfare concerns. A significant number of neonatal deaths could be avoided by preventive management, early diagnosis, and consequently well-timed intervention. The aim of the study was to evaluate the use of umbilical artery Doppler to predict the vitality score (APGAR) of lambs at birth, and its use as a screening tool for detecting high-risk neonatal cases in the last week of gestation, describing changes in the resistivity and pulsatility index in singletons and twins. Materials, Methods & Results: A total of 27 White Dorper pregnant ewes were studied: 19 multiparous (ewes, 2 to 4-yearsold) and 8 primiparous (yearling, up to 1-year-old). From 130 days of pregnancy, gestational ultrasound was performed weekly until delivery, but only data from the last pre-partum scan for each ewe was included. The inclusion criteria for the analysis of the umbilical arteries Doppler were the positioning of the fetus and the quality of the images obtained. Identification of each of the twin fetuses after birth was performed by reference to ultrasound fetometry and its correlation with birth weight. The vitality score at birth (APGAR) was used to classify each group, regardless of the characteristic of eutocic or dystocic delivery, with Group 1 lambs having normal vitality (APGAR = 7) and Group 2 lambs having low vitality (APGAR < 7). A transabdominal Doppler ultrasound of 28 fetal umbilical arteries was performed in the last week before delivery (146 ± 2.4 days of gestation), and the results were compared with the vitality scores of lambs at birth. There were 53.6% of lambs (15/28) with normal vitality scores (Group 1), and 46.4% of lambs (13/28) had low vitality scores (Group 2). The umbilical artery Doppler ultrasound analyzes of the resistance index (RI), the pulsatility index (PI), and the RI and PI oscillations determined by the resistivity index gradient (RIgrad), the resistivity index variations (RIvar%), the pulsatility index gradient (PIgrad) and the pulsatility index variation (PIvar%) were established for each fetus. Pearson's correlation was performed for each umbilical artery Doppler ultrasound variable and vitality score of each lamb, and the T Student's test was performed between Groups 1 and 2. There were no statistically significant differences between groups. Furthermore, the RI values or oscillations did not correlate with the lambs' vitality score, and mildly increased PI values need to be interpreted with caution. Neonatal vitality in lambs was correlated with pulsatility index oscillations: PIgrad (r = 0.4005; P = 0.0346) and PIvar% (r = 007; P = 0.0299). Discussion: Measurement of umbilical artery RI and PI is possible in ewes with singleton and twin pregnancies in the last week of gestation. High PI of the umbilical artery did not correlate with a low lamb vitality score at birth, as previously described in human fetal medicine. The PI alone cannot be correlated with APGAR in lambs, but the PIgrad and PIvar% analyzes should be performed. In conclusion, the RI and PI values, if analyzed in isolation, show no correlation with the vitality scores of lambs at birth. However, making multiple measurements to derive associations between maximum and minimum values of PI such as PIgrad and PIvar% in the same fetus, could help to screen for high-risk neonates. [ABSTRACT FROM AUTHOR]

The objective was to determine the effect of grazing fodder beet versus ryegrass-dominant pasture from mid-to-late gestation on dam and offspring performance under practical farming conditions. Twin-bearing ewes were randomly allocated to grazing regimes of either fodder beet plus ad libitum ryegrass/clover hay (FB; n = 100) or ryegrass-dominant pasture plus ad libitum ryegrass/clover hay (RG; n = 100) with three replicates per group, from pregnancy day (P) 100–110 to birth. At P135, 10 ewes per treatment were randomly selected from each replicate, slaughtered and back fat and eye muscle depth and fetal body weight and composition were measured. Samples were evaluated for selected blood metabolites. Ewe BW and BCS change and lamb growth were measured, and lamb survival from birth to weaning calculated. Compared with RG, FB ewes had lower ADG and overall lower BCS resulting from increased mobilisation of both fat and muscle. Lambs born to FB-ewes had lower BW and postnatal growth rates and increased mortality from birth to weaning (29% versus 12%). Body composition and blood parameters indicated that FB compared to RG ewes were subject to undernutrition. This study provides new insights into the consequences of FB grazing regimes, as an alternative to ryegrass pasture, on animal performance. [ABSTRACT FROM AUTHOR]

Background: Toxoplasma gondii causes reproductive losses in sheep worldwide, including Australia. The reproductive performance of primiparous ewes is typically lower than for mature, multiparous ewes, and younger ewes are more likely to be immunologically naïve and therefore more susceptible to reproductive disease if T. gondii infection occurs during pregnancy. The aim of this study was to assess the impact of infection with T. gondii on the reproductive performance of primiparous ewes in southern Australia using a prospective cohort study. This will inform the need for targeted control strategies for T. gondii in Australian sheep. Results: Toxoplasma gondii seropositivity using indirect ELISA was detected at 16/28 farms located across southern Australia. Apparent seropositivity to T. gondii was lower in primiparous ewes (1.1, 95% confidence interval (CI) 0.6, 1.8) compared to mature, multiparous ewes (8.1, 95% CI 6.0, 10.5; P < 0.001). Toxoplasma gondii seroconversion during the gestation and lambing period was confirmed for 11/1097 (1.0, 95% CI 0.5, 1.7) of pregnant primiparous ewes that failed to raise a lamb, and 1/161 (0.6, 95% CI 0.1, 2.9) primiparous ewes with confirmed mid-pregnancy abortion. Conclusions: Low frequency of detection of T. gondii seroconversion during gestation and low frequency of seropositivity to T. gondii suggests that toxoplasmosis was not an important contributor to reproductive losses in primiparous ewes on farms located over a wide geographical area in southern Australia. [ABSTRACT FROM AUTHOR]

Neospora caninum has been implicated as a sporadic cause of abortion and perinatal deaths in sheep flocks globally. However, its significance as a reproductive pathogen for sheep in Australia remains unknown. The aims of this study were to (i) determine the seroprevalence of N. caninum in Australian breeding ewes and (ii) examine if natural exposure to N. caninum is associated with poor reproductive performance of primiparous ewes in southern Australia. Thirty flocks of primiparous ewes (aged 1–2 years old at lambing) from 28 farms in three states (Western Australia, South Australia and Victoria) were monitored between mating and lamb marking. Blood samples were also collected from multiparous mature ewes (aged 3 years or older) at each farm. Seroprevalence for anti-N. caninum IgG using indirect ELISA was determined for a subset of primiparous ewes that were predominantly determined to be pregnant and subsequently failed to rear a lamb (n = 1279) and randomly selected mature multiparous ewes with unknown reproductive status (n = 558). Neopsora caninum apparent seroprevalence was 0.16% (95% confidence interval 0.03%, 0.5%) in primiparous ewes, with seropositivity identified in two ewes from farms located in South Australia and Victoria. There was no evidence of seropositivity in mature ewes with apparent seroprevalence 0% (0%, 0.45%). These findings suggest that N. caninum infection was not widespread in primiparous ewes or mature multiparous ewes on these farms, and exposure to N. caninum infection was unlikely to explain abortion and perinatal mortalities observed for primiparous ewes. [ABSTRACT FROM AUTHOR]

A cross-sectional study was conducted to assess incidences of lamb mortality in low input farming systems in the Eastern Cape province. Four villages (Ndakana, Kwa-Masele, Qhugqwala and Ndindwa) and 18 households were selected. Data was collected from 399 lambing records from June 2017 to May 2018 whereby an analysis of factors affecting lamb mortalities (i.e. sex of lamb, season of birth, age of ewe and village) were investigated. With the exception of age of ewe, the variables had a significant (P <0.001) effect on lamb mortality. Qhugqwala had the highest lamb mortality (28.8%) compared to the other villages. Mortality rate was higher in the male lambs (61%) compared to female lambs (39%). Lambs born in spring had higher mortality rate (58%) compared to 42.4% in lambs born in winter. This study confirmed that overall mortality rate averaged 33% from birth to yearly weaning. Season of birth, sex of a lamb and location were the major contributing factors to lamb mortality under low input farming systems. [ABSTRACT FROM AUTHOR]

• In the present study, survival analysis was performed using of time-dependent variable and censored data via gibbs sampling method. • The non-genetic effects had a significant effect on lamb survival from birth to the last recording date. • Estimated direct heritability for survival ranged 0.097 to 0.157. The contribution of maternal permanent environmental variance ratio was estimated higher than maternal heritability. • Improvement of survival for Sangsari breed could be possible through management practice as well as genetic selection. The aim of this study was to investigate the genetic and non-genetic effects on survival traits of Sangsari sheep from birth to the last recording date. Data base with 35,470 sheep survival records was collected during 1988 to 2010 in 11 flocks by the Animal Breeding Center of Iran. The non-genetic effects were evaluated on hazard rate of sheep in different times with survival and cmprsk packages. Exponential distribution based on censored data was used to estimate the genetic parameters of the survival from birth to the last recording date. The linear animal models were fitted using Bayesian method via Gibbs sampling of the MCMCglmm package. The overall mortality rate for Sangsari lambs was 2.00 and 25.72% for birth to 100 and 500 day of age, respectively, and its value increased upto 90.54% till 3400 day of age. The results indicated that the year and month of birth, sex of lamb, birth weight, age of ewe, flock (P < 0.001), and type of birth (P < 0.01) had a significant effect on sheep survival. Estimated direct heritability for survival from birth to the last recording date by different linear models ranged 0.097 to 0.157. The contribution of maternal permanent environmental variance ratio was estimated higher than maternal heritability, thus this effect must be considered in the evaluation models for improving sheep survival. The present findings suggest that sheep survival improvement could be possible through management practice as well as genetic selection. [ABSTRACT FROM AUTHOR]

In a previous study we investigated the association between two single nucleotide polymorphism (SNP) genotypes, namely steroid 17-alpha-hydroxylase/17,20 lyase (CYP17) SNP628 and dopamine receptor D2 (DRD2) SNP939, with two temperaments (calm and nervous) in Australian Merino sheep and concluded that the DRD2 SNP939 T/T genotype combined with the CYP17 SNP628 G/G genotype is associated with a calm temperament and could be used as a potential marker for calm sheep, whereas the DRD2 SNP939 C allele combined with the CYP17 SNP628 A/A genotype is associated with a nervous temperament and could be used as a potential marker for nervous sheep. In sheep, the association between temperament and reproductive performance has been determined, but the association of these two SNP genotypes with sheep reproduction has not been investigated. Therefore, using Chinese Sinkiang Merino sheep, the present study investigated the association of the two CYP17 SNP628 and DRD2 SNP939 genotypes with sheep reproductive performance. Sheep with the DRD2 SNP939 T/T genotype combined with the CYP17 SNP628 G/G genotype had a higher ovulation rate, multiple gestation rate, better maternal behaviour and lower lamb mortality. Thus, the results of this study contribute to our knowledge of the association between genotypes and reproduction in sheep, which is beneficial for sheep genetics and breeding. In sheep, the association between temperament associated with two single nucleotide polymorphism (SNP) genotypes and sheep reproduction has not yet been studied. This study investigated the association between steroid 17-alpha-hydroxylase/17,20 lyase (CYP17) SNP628 and dopamine receptor D2 (DRD2) SNP939 genotypes and concluded that sheep with the DRD2 SNP939 T/T genotype combined with the CYP17 SNP628 G/G genotype had better reproductive performance and maternal behaviour. The findings may be beneficial for sheep genetics and breeding. [ABSTRACT FROM AUTHOR]

An investigation of stillbirth and early neonatal lamb mortality was conducted in sheep flocks in Norway. Knowledge of actual causes of death are important to aid the interpretation of results obtained during studies assessing the risk factors for lamb mortality, and when tailoring preventive measures at the flock, ewe and individual lamb level. This paper reports on the postmortem findings in 270 liveborn lambs that died during the first 5 days after birth. The lambs were from 17 flocks in six counties. A total of 27% died within 3 h after birth, 41% within 24 h and 80% within 2 days. Most lambs (62%) were from triplet or higher order litters. In 81% of twin and larger litters, only one lamb died. The most frequently identified cause of neonatal death was infectious disease (n=97, 36%); 48% (n=47) of these died from septicaemia, 25% (n=24) from pneumonia, 22% (n=21) from gastrointestinal infections and 5% (n=5) from other infections. Escherichia coli accounted for 65% of the septicaemic cases, and were the most common causal agent obtained from all cases of infection (41%). In total, 14% of neonatal deaths resulted from infection by this bacterium. Traumatic lesions were the primary cause of death in 20% (n=53) of the lambs. A total of 46% of these died within 3 h after birth and 66% within 24 h. Severe congenital malformations were found in 10% (n=27) of the lambs, whereas starvation with no concurrent lesions was the cause of death in 6% (n=17). In 16% (n=43) of the lambs, no specific cause of death was identified, lambs from triplet and higher order litters being overrepresented among these cases. In this study, the main causes of neonatal lamb mortality were infection and traumatic lesions. Most neonatal deaths occurred shortly after birth, suggesting that events related to lambing and the immediate post-lambing period are critical for lamb survival.

Introduction Lamb production is the largest part of income in sheep industry. Therefore, the mortality rate of lambs is a key factor in profit of the sheep breeding. Mortality rate of lambs (or Lamb mortality rate) in different breeds of sheep under different climatic conditions is varying from 15% to 50% and an average of 9% to 20% has been reported. Survival rate is a combination trait that is influenced by various factors such as management, weather condition, and behavior of dam and lamb, as well as genetic effects. Quantification of non-genetic effects on mortality rate can be useful in controlling lamb survival rate and increasing profitability of sheep breeding. Therefore, identification of genetic and environmental factors affecting the productive capacity of indigenous breeds in different area is the main priority that should be considered in breeding programmes. Therefore, the objective of this study was to estimate genetic and environmental factors of growth traits and mortality in Karakul lambs. To estimate the genetic and environmental parameters of Karakul lambs before weaning growth and mortality records of 4929 lambs from 207 rams and 1856 ewes at Sarakhs Karakul sheep breeding station, from 1994 to 2009 were used. Materials and Methods The data were used in this study included a total of 4929 record of lamb birth weight, 1 and 3 months of age, average daily gain from birth to weaning (growth traits before weaning) and mortality rate of lambs from birth to 1, 2, 4, 8 and 14 weeks (mortality rate of lambs before weaning). Data were collected during the years 1994 to 2010 in karakul breeding station in Sarakhs. The data were edited and pedigree file and data file were prepared. Uni-variate animal model was used to estimate the genetic parameters as following: where is the vector of record, b is the vector of fixed effects (year, sex, type of birth, age of dam), a is the vector of direct additive genetic effects, m the vector of maternal additive genetic effects, X, Z1 and Z2 are the matrix of coefficients (0 and 1) that relate b, a and m to records and e is the vector of residuals. Analysis of each trait was performed considering the significant factors in the model including sex, birth-type, birth-year, dam-age and ewe weight at birth. In the analysis of maternal effect model for growth traits and Cox regression for mortality traits were used. Cox Regression in SPSS software was also used to calculating the survival function. (Co) variance components were estimated by Restricted Maximum Likelihood (REML) with uni-variate animal model. The genetic, phenotypic and environmental trends were estimated as regression of average breeding values on year of birth, regression of average phenotypic values on year of birth and, difference between genetic and phenotypic trends, respectively. Results and discussion The results showed that year of birth had a significant effect on all traits (P

Using climatic data from 1991 to 2016 recorded at Avikanagar, wind chill index (WCI) was calculated for each day during winter (December-February) coinciding with major lambing season. The WCI (kcal/m2/h) was categorized as no chill (<300.0), low (<300.1-350.0), moderate (350.1-400.0), high (400.1-450.0) and extreme (>450.1) and the neonatal lambs death (857) in a total of 2257 days (December-February of each year) were considered to observe the effect of WCI. The overall annual neonatal lamb mortality was 5.85%. Over the years daily WCI revealed a significant increase in number of extreme chill days (WCI > 400.1 kcal/m2/h) since December 2003. The overall proportion of neonatal death ranged from 2.10% (WCI < 300 kcal/m2/h) to 69.34% ((WCI > 400.1 kcal/m2/h). The climatic data showed that out of total days, majority of days (64.99%) covered were of high to extreme chill in nature (WCI > 400.1 kcal/m2/h). The daily rate of neonatal mortality found to possess a positive and linear relation with WCI and ranged from 0.25 lamb death/day (WCI < 300 kcal/m2/h) to 0.46 lamb death/day (WCI > 450.1 kcal/m2/h). The entities responsible for exposure-inanition syndrome (EIS, debility, exposure, inanition) had positive relation with WCI. The contribution of EIS in overall neonatal mortality ranged from 29.08 (WCI 300.1-350.0 kcal/m2/h) to 42.00% (WCI > 450.1 kcal/m2/h). The analysis suggested requirement of proper shelter management for neonatal lambs during extreme climate. [ABSTRACT FROM AUTHOR]

The genetic parameters for maternal rearing-ability of ewes were investigated by ignoring or defining the rearing ability trait separately by litter-size class (singles versus multiples) using multi-generational data from three, fully pedigreed Merino flocks differing in prolificacy, production level and environment. Genetic correlations (ra) between litter size (LSIZE) and the percentage of lambs surviving (PLSURV) were more negative with an increasing mean flock litter size (ra: -0.21 ± 0.17 to -0.73 ± 0.08), while the corresponding range in phenotypic correlations (rp) was substantially lower (rp: -0.15±0.01 to -0.33±0.01). Rearing-ability traits defined separately by litter-size class were highly correlated (ra: 0.49± 0.19 to 0.64±0.38), but not genetically identical traits in the most prolific flock. Defining rearing-ability traits separately by litter-size class reduced the antagonistic genetic correlations between LSIZE and PLSURV to between -0.39±0.14 and 0.14 ±0.28, through accommodating the change in mean and variance of PLSURV with LSIZE. Similarly, linear transformation (TSURV) of PLSURV within each litter size to a common mean and variance reduced the antagonistic trend in genetic correlations between LSIZE and TSURV to range between -0.05±0.17 and -0.43±0.13. Since genetic correlations are low to moderate between TSURV and LSIZE, it is possible to select for improvements in both the number of lambs born and lamb survival simultaneously. Defining rearing-ability traits separately by litter-size class and the role of transformation will be investigated further for improving the accuracy of genetic evaluation for rearing ability across a range of flocks, breeds and environmental conditions using more extensive industry data. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine factors affecting lamb birth weight (BWT) and differences between BWT of the largest and smallest littermates (BWTD) and to assess the relative importance of BWT and BWTD on lamb survival and growth to weaning. Records from twin (n = 5369) or triplet (n = 1664) litters born on pasture were utilised. Breeds included Coopworth, Romney, Perendale, composite and Texel. Ewe and sire breed, age and weight of the dam, sex, and number of lambs born (NLB) affected BWT. Neither embryo loss nor ovulation pattern (i.e. all ova released from one ovary or some from each) were associated with BWT. Dam weight and NLB affected BWTD but dam age, sire or dam breed did not. Loss of an embryo reduced BWTD, and BWTD was lower when the ewe ovulated from both ovaries versus only one ovary for twins, but not triplets. Whereas BWT was moderately heritable (h 2  = 0.20), BWTD was not heritable (h 2  = 0.003). Lamb survival was positively associated with BWT. Lambs with BWTD > 1.3 kg were less likely to survive (73.3%) than those from litters of smaller BWTD (range 82.8–85.7% survival). Growth rate of twin and triplet lambs was positively associated with BWT. Surprisingly, lambs from litters with moderately high BWTD had slightly greater (approximately 3%) growth rate than those from lambs of low to intermediate BWTD. Thus, while large BWTD were negatively associated with survival, BWT itself, which was moderately heritable, appeared to be a stronger driver of lamb survival and average daily gain. [ABSTRACT FROM AUTHOR]

Lamb survival is essential for successful rearing of lambs for sale and replacement of breeding stock given a profitable sheep enterprise. The present study was conducted using the data on 4694 Avikalin, 5015 Chokla and 5718 Malpura sheep recorded from 1991 to 2016 for studying the neonatal mortality in lambs. The effect of influential factors on neonatal mortality of lambs was ascertained and the genetic parameters for lamb survival till first 28 days of life using Gibbs sampling were estimated. Incidence of neonatal mortality was 4.29%, 5.17% and 4.07% in Avikalin, Chokla and Malpura sheep, respectively. Logistic regression analysis revealed significant impact of year of birth and lamb's birth weight on neonatal mortality for all the breeds. Year (1997, 2011–12) negatively affected the survival due to sudden shift in policy decision. Dams with low body weight and in their first parity were also found to affect the lamb survival negatively. Due care of the lambs born with low birth weight (< 2.00 kg) and for primi-parous dams with low weight (< 20.00 kg) can improve the chances of lamb survival. Genetic analysis revealed that the direct heritability for Avikalin sheep was 0.17 ± 0.02, indicating scope for genetic improvement through selection. However, for Chokla and Malpura sheep the direct heritability were 0.05 ± 0.00 and 0.06 ± 0.01, respectively. Maternal permanent environmental effect was important in Avikalin and Chokla sheep with maternal heritability estimates of 0.10 and 0.11, respectively. However, for Malpura sheep, with little genetic variance, only direct genetic effect was important. Apart from care and management, accounting for both direct and maternal effects in breeding program can improve the lamb survival. [ABSTRACT FROM AUTHOR]

This study was aimed to recognize the reproductive performance and herd composition of sheep and goat in six studied area located in east and west river Nile at Assiut governorate. A set of semi-structured questionnaire was used to collect information from 300 sheep owners based on single-visit-interviews. The study revealed that farmers keep mixed livestock species. Sheep and goat production are the major livestock activity in located study area. The average farm size of households surveyed in Assiut Governorate was 8.2 feddan. The farmers cultivated 50.74% and 50.86 % of their lands for green fodder and field crops in winter and summer, respectively. About 50.89 % of the total farm size area cultivated with animal fodder around the year. In summer 25.37%. Of the area was cultivated with field crops. The reproductive and productive performance of sheep and goats were discussed and data showed that, no significant differences were observed in lambing interval and age at first lambing between sheep and goats, while goats were significantly higher in litter size (P<0.01), lambing mortality (p<0.05) weaning weight (p<0.01) and age at marketing (p<0.05) than sheep. Generally, Sheep and goat production in the studied areas was constrained by different problems; where the major ones are availability and cost of feeds, limitation of land for the expansion of production and poor extension services. Sheep and goats are very important smallholder producers due to their biological factors such as short generation interval, twinning, short growth periods, do not require much space and low food requirements. In this domain, reasons of high lamb mortality rates should be identified and reduced in order to make sheep and goat production profitable and sustainable. [ABSTRACT FROM AUTHOR]

Neonatal lamb mortality is a major economic and welfare issue for Australian sheep producers. The contribution of udder and teat traits of the dam to the survival and subsequent growth of the lamb is relatively unknown. This study aimed to estimate phenotypic and genetic parameters associated with objectively measured and visually scored udder and teat traits in Australian Merino sheep, and to evaluate the impacts of udder and teat traits of the dam on survival and growth of their lambs to weaning. Ewes from the New England Merino Lifetime Productivity flock (n = 1341 ewes) were assessed for udder and teat traits, and phenotypic and genetic parameters for individual traits and relationships among them were estimated using linear mixed models. Odds ratios were calculated to investigate the influence of udder soundness on lamb mortality. Further, the influence of udder traits on variation in lamb weaning weight was explored. Measured udder and teat size traits were estimated to have moderate to high heritabilities (0.32 (0.09) to 0.56 (0.10)), while the heritabilities of visually scored traits were lower (0.09 (0.05) to 0.17 (0.07)). Measured traits were highly correlated genetically with their equivalent visually scored traits. The odds ratio of mortality for lambs born to ewes with unsound versus sound udders was 1.54 (95 %CI 1.1–2.2, P < 0.05). The odds ratio of lamb mortality from starvation compared to all other causes of death for lambs born to ewes with unsound versus sound udders was 4.62 (95 %CI 2.4–8.9, P < 0.001). Dam udder and teat traits collectively contributed 8 % of the variation in lamb weaning weight observed. Results suggest that targeting optimal ewe udder and teat characteristics in sheep breeding programs has the potential to significantly improve lamb survival and growth in extensive production systems. • Udder and teat traits are moderately heritable in Australian Merinos. • Genetic relationships among udder and teat traits are generally favourable. • Lambs born to ewes with unsound udders are at increased risk of neonatal mortality. • Including ewe udder traits in breeding programs could improve lamb survival and growth. [ABSTRACT FROM AUTHOR]

Aim: To identify the Clostridium perfringens toxin genotypes prevailing in enterotoxemia suspected sheep flocks in Andhra Pradesh by using multiplex PCR. Materials and Methods: Intestinal scrapings were collected from lambs below three months of age from flocks with similar management from different Districts of Andhra Pradesh, in India. A total of 208 samples were collected with 140 from enterotoxemia suspected flocks and 68 from healthy flocks. Following processing and culture of the samples, colonies were identified by morphological and biochemical tests. All the clostridial isolates were analyzed by multiplex PCR. Results: C. pefringens were isolated from 97 out of 140 enterotoxemia suspected flocks (69.29%) and 27 out of 68 healthy flocks (39.71 %). Genotyping of the 97 iolates by multiplex PCR from enterotoxemia suspected flocks indicated C. perfringens type A, C and D 67.01% (65 out of 97); 11.34% (11 out of 97) and 21.65% (21 out of 97) respectively. Isolates from healthy flocks indicated the presence of type A and D 92.59% (25 out of 27) and 7.40% (2 out of 27) respectively. Number of isolates from enterotoxaemia suspected flocks were significantly high (P

This study was carried out using 94 ewes at Erbil plain - Kurdistan region-Iraq, during the period from May 2016 to April 2017. The overall mean mortality rates from birth to 7 days and from 8 days to weaning age were 8.6 and 6.6%, respectively. Age of dam, type of birth, weight of the dam at matting, Body Condition Score (BCS) and birth weight had an important significant (P<0.05) impact on lamb mortality from birth to 7 days and from 8 days to weaning age. This research revealed that a higher lamb mortality (4.2%) was registered for dams aged 2 years, while a lower mortality(6.6%) was found in dams aged 5-6 years, no significant differences in mortality among males and females were appeared, male lambs showed a higher mortality than females, type of birth showed an important impact (P<0.05) on lamb mortality. Single born lamb mortality was 5.5%, whereas that of the twin born lamb was significant (13.6%). Ewes with the (BCS) of 2-3 showed a higher mortality (14.2%), while those ewes with (BCS) more than 3 recorded the lowest lamb mortality (5.4%). Lambs weighting less than 3 kg at birth registered a higher mortality compared with lambs weighing 3 kg, or more which showed the lowest mortality. It has appeared from the results of this study that most of the non-genetic factors studied involve: Age of dam, type of birth, birth weight, and weight of the dam, and body condition score showed a substantial significant influence on lamb mortality between birth and weaning of Kurdi sheep. [ABSTRACT FROM AUTHOR]

Perinatal lamb mortality is a major challenge for sheep producers worldwide. Lamb losses from ultrasound pregnancy scanning to lamb marking were assessed in 125 mobs of ewes sourced predominantly from sheep flocks in southern New South Wales. In total, 103 086 lambs were marked from100 165 ewes present at joining. Despite the majority of producers undertaking best-practice ewe management, including ultrasound scanning for pregnancy and preferential feeding of multiple bearing ewes, losses were similar to those reported previously (11% and 29% for singles and twins respectively). Non-Merino ewes had significantly lower losses than did Merino ewes, irrespective of ram type (13% versus 21%, P < 0.001). There was a tendency for mob size in twin-bearing ewes to influence survival, with a lower mob size (<200) having lower losses (29% versus 33%, P = 0.07). These results are discussed in the context of existing extension advice about ewe management and perinatal lamb mortality. [ABSTRACT FROM AUTHOR]

Neonatal lamb mortality constitutes a significant economic cost and is an important welfare challenge. Despite compelling evidence for reduction strategies and cost benefits associated with them, there has been no documented reduction in mortalitysince the 1970’s. We aimed to evaluate whether a knowledge exchange solution could be used to define farm specific loss risks accurately. This was done by training farmers how to examine neonatal lambs post-mortem to record and interpret common causes of mortality by following a basic framework. We used participatory rural appraisal to assess some of the existing challenges to reducing lamb mortality. When considering outcomes for specific post mortem questions, there was 87.5% agreement between veterinary and farmer answers and 82.3% of farmer diagnoses ( n = 96) agreed with the veterinary conclusions. When merged with farmer performed post-mortems, farm specific mortality pie-charts were developed to highlight the variation between flocks and the necessity for flock specific advice. Common challenges to reducing lamb loss included level of labour, skill set of labour, communication within teams and whether farmers generally considered post-mortems to be a valuable tool. We consider that farmer post-mortems of lambs could be a tool for the veterinary-farmer team, facilitating the communication of farm specific advice and empowering farmers to effect positive change. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the pre-weaning survival rates of Awassi lambs and identify the causes of death in extensive and semi-extensive production systems. The study was designed to collect data under field conditions. Data were recorded on 29,290 lambs born alive during lambing seasons from 2011 to 2015. Postmortem autopsy findings were collected from 5448 lambs died during the pre-weaning period. About 63.5% of losses occurred during the first 7 days of life. The overall pre-weaning mortality rates were 19.7% and 16.9% in the extensive and semi-extensive production systems, respectively. Lamb birth weight had a strong effect (P<0.0001) on the pre-weaning mortality rate. The mean mortality rate in lambs weighed <2 kg at birth was 45.1%. The proportion of autopsied lambs dying by category was starvation (28.6%), respiratory infections (19.2%), gastrointestinal infections (16.2%), birth injuries (10.2%), hypothermia (8.6%), enterotoxaemia (8.2%), dystocia (4.4%) and predation (2.1%). Explanatory variables best used by Weibull model to estimate the hazard ratio (HR) of lambs falling into a certain death category were production system, lamb sex, birth type, and lamb birth weight. Lambs born in extensive production system were more (P<0.0001) likely to die from starvation (HR=4.6), gastrointestinal infections (HR=3.2), and hypothermia (HR=2.2), compared with semi-extensive system. Lambs weighed <2 kg at birth were more (P<0.0001) likely to die from starvation (HR=5.5), hypothermia (HR=3.6), gastrointestinal infections (HR=2.4) and respiratory infections (HR=2.2), compared with lambs weighed 3–4 kg. Triplet lambs were 4.6 more (P<0.0001) likely to die from hypothermia and 4.3 more (P<0.0001) likely to die from starvation. Survival rates of Awassi lambs can be improved by applying appropriate management practices that target intermediate birth weights and minimize the infectious diseases, starvation and cold stress. [ABSTRACT FROM AUTHOR]

Lamb output from the ewe flock is a key determinant of the profitability of sheep farming. Here, we assessed the association between various factors (ewe breed, month of birth, year of birth, birth type, lamb sex and lamb birth weight) on lamb mortality (within the first 60 days of life) using data collected in northern Turkey between 2006 and 2014. The study included a total of 1958 lambs, including the Romanov (R), Awassi (I), Kivircik (K), Tuj (T), Anarom (AN), R×I (Romanov×Awassi), R×K (Romanov×Kivircik), R×A (Romanov×Akkaraman), R×M (Romanov×Morkaraman) and F1 Romanov (Romanov× Turkish native) breeds. CHAID (Chi-Square Automatic Interaction Detector) analysis correctly classified 99.2% of surviving lambs and 12.4% of dying lambs, while 100% of surviving lambs and no dying lambs were correctly classified by logistic regression analysis. CHAID and logistic regression analyses correctly determined 91.5% and 91.1% of lamb mortality, respectively. The most important variables for the estimation of lamb mortality in the CHAID and logistic regression models were month of birth and lamb breed. Based on our findings, we propose that the CHAID algorithm (AUC of 0.843) is better to classify lamb mortality than a logistic regression analysis approach (AUC of 0.613). [ABSTRACT FROM AUTHOR]

An investigation of stillbirth and early neonatal lamb mortality was conducted in sheep flocks in Norway. Knowledge of actual causes of death are important to aid the interpretation of results obtained during studies assessing the risk factors for lamb mortality, and when tailoring preventive measures at the flock, ewe and individual lamb level. This paper reports on the postmortem findings in 270 liveborn lambs that died during the first 5 days after birth. The lambs were from 17 flocks in six counties. A total of 27% died within 3 h after birth, 41% within 24 h and 80% within 2 days. Most lambs (62%) were from triplet or higher order litters. In 81% of twin and larger litters, only one lamb died. The most frequently identified cause of neonatal death was infectious disease (n = 97, 36%); 48% (n = 47) of these died from septicaemia, 25% (n = 24) from pneumonia, 22% (n = 21) from gastrointestinal infections and 5% (n = 5) from other infections. Escherichia coli accounted for 65% of the septicaemic cases, and were the most common causal agent obtained from all cases of infection (41%). In total, 14% of neonatal deaths resulted from infection by this bacterium. Traumatic lesions were the primary cause of death in 20% (n = 53) of the lambs. A total of 46% of these died within 3 h after birth and 66% within 24 h. Severe congenital malformations were found in 10% (n = 27) of the lambs, whereas starvation with no concurrent lesions was the cause of death in 6% (n = 17). In 16% (n = 43) of the lambs, no specific cause of death was identified, lambs from triplet and higher order litters being overrepresented among these cases. In this study, the main causes of neonatal lamb mortality were infection and traumatic lesions. Most neonatal deaths occurred shortly after birth, suggesting that events related to lambing and the immediate post-lambing period are critical for lamb survival. [ABSTRACT FROM AUTHOR]

O presente trabalho objetiva relatar os principais tipos de distocias em ovelhas, no Agreste e Sertão de Pernambuco, e avaliar alguns fatores relacionados com sua ocorrência, bem como determinar a eficiência dos tratamentos utilizados. A maior incidência de partos distócicos ocorreu na estação chuvosa, com 61,7% dos casos. Os resultados mostraram predominância de distocias de origem materna (71,6%) sobre a fetal (29,4%), com maior incidência em ovelhas primíparas da raça Santa Inês, com gestações gemelares. A principal distocia materna foi a ausência ou dilatação cervical insuficiente, e fetal, a má disposição na apresentação anterior. A taxa de sobrevivência das mães correspondeu a 100 e 88,6%, enquanto das crias alcançou 41,2 e 46,7%, após manobra obstétrica e cesariana, respectivamente, com predominância de cordeiros inviáveis em ambos os procedimentos. As manobras obstétricas e a cesariana pelo flanco esquerdo permanecem opções seguras para o tratamento de distocias em ovelhas, sendo ainda importantes coadjuvantes, minimizando o impacto econômico causado por essa enfermidade em Pernambuco.The aim of the present study was to report the main dystocia causes in sheep in Agreste and semiarid region of Pernambuco and to evaluate some factors related to their occurrence, besides of determining the efficiency of the treatment choices. The higher incidence of dystocia occurred in rainy season corresponding to 61.7%. Results showed a major predominance of maternal dystocia (71.6%) over fetal dystocia (29.4%) with higher incidence in primiparous and gemelar pregnant Santa Inês ewes. The main maternal dystocia was ringwomb while fetal dystocia was maldisposition in anterior presentation. Maternal survival rate correspond to 100% and 88.6%, while lambs achieved 41.2% and 46.7% after obstetrical maneuver and caesarean section, respectively, with predominance of unviable lambs in both procedures. Obstetrical maneuver and left flank cesarean section remain as safe options for the treatment of sheep dystocia and are also important coadjutants in minimizing the economical impact that this disease causes in Pernambuco.

Neonatal lamb mortality represents both a welfare issue (due to the considerable suffering and distress) and an important production inefficiency. In lambs, approximately 80% of mortality can be attributed to the starvation–mismothering–exposure complex and occurs in the first 3 days after birth. It was the object of this review to determine the micronutrient(s) most likely to have a positive effect on neonatal lamb survival when included above the requirement for that micronutrient. Micronutrients discussed were Co, Cu, I, Fe, Mn, Se, Zn, vitamins A and E and n-3 fatty acids. For Co, Fe, Mn and Zn, there was no evidence of positive responses to supplementation. Cu and I had toxicity thresholds that were sufficiently close to requirement that supplementing above requirement presented a risk of inducing toxicity. In the case of vitamin A, while serum concentrations indicated that sub-optimal status did exist, long-term buffering from liver stores (from grazing) makes experimentation difficult and practical benefits to supplementation unlikely. Therefore, the most likely candidates for supplementation were Se, vitamin E and fatty acids. Fatty acid supplementation with fish oils or docosahexaenoic acid-containing algal biomass consistently improved lamb vigour but it is unlikely that supplementation will be economic. Positive responses to Se supplementation throughout gestation were recorded. However, in many studies the Se status of control ewes was marginal and there is a need for more studies where control ewes are clearly adequate in Se. Positive responses to vitamin E supplementation above requirement in the last-third of gestation were observed but the optimum dietary inclusion of vitamin E and period of feeding during pregnancy still require clarification.

A significant number of lambs born each yr in Australia die within 72 h of birth. Periods of high wind, combined with rain and low temperatures, can lead to marked increases in the level of mortality. Under these weather conditions mortality levels may be reduced with the provision of shelter, provided it is utilized by lambs. This study used GPS collars to determine the use of shelter by ewes and lambs, to compare the movement of ewes with twin lambs across 2 types of shelter (hedgerows and shrubs), while also comparing ewes with single and twin lambs in a single shelter type (hedgerows). Additionally, the birth sites of 364 lambs and death sites of 252 lambs were recorded across the 3 shelter type and litter size combinations (Twins in shrubs, Twins in hedgerows, Singles in hedgerows) plus an unsheltered group (Singles in unsheltered). A higher (P < 0.001) than randomly expected percentage of ewes lambed in the areas closest to both shelter types; in the shrub shelter 42% of ewes lambed within 2.5 m of shrub rows compared to an expected 11% based on the proportion of the paddock this area constituted. Despite the higher than expected percentage of ewes lambing close to the shelter rows, ewes in both twin lamb shelter types avoided the areas close to the shelter before and after lambing (Hedgerows-2.5 m; Shrubs- 6.25 m) and single bearing ewes showed no preference for or against these areas. With a high proportion of twin bearing ewes lambing close to the shelter, a design that reduces the potential for ewe and offspring separation while providing good shelter will offer the greatest potential reduction in newborn twin lamb mortality arising from exposure. [ABSTRACT FROM AUTHOR]

This experiment was conducted to investigate the effect of pre-pubertal plane of nutrition on the skeletal growth, lamb mortality, insulin-like growth factor 1 (IGF-1) concentrations, quantity and quality of colostrum produced in ewe lambs. A total of 40 clinically health Kurdish female lambs (30±8.6 d and weighing 10.2±3.4 kg) were randomly allocated to one of two experimental diets in pre-weaning period: high quality diet (HQD, 2.50 Mcal ME/kg dry matter (DM) and 148 g CP/kg DM) or low quality diet (LQD, 2.02 Mcal ME/kg DM and 87 g CP/kg DM). At weaning, one half of lambs from each group was randomly separated and assigned to HQD or LQD. So there were four treatment groups in post-weaning period: H-H (HQD preand post-weaning); H-L (HQD pre-weaning and LQD post-weaning); L-H (LQD pre-weaning and HQD post-weaning) and L-L (LQD pre and post-weaning, control group). Weekly DM intake was determined. Serum IGF-1 concentrations was determined by ELISA method. The HQD treatment increased DM intake and BW (body Weight) compared with the LQD treatment during pre-weaning period (P<0.01). At 210 d of age, animals fed LQD during the pre-weaning period and HQD during the post-weaning period (L-H sequence) had greater body length (BL), wither height (WH), hip height (HH) and hip width (HW) than animals on the H-L sequence. No interaction of the two periods was detected for heart girth, HW, WH, BL at 210 d of age (P>0.05). HW at weaning time was not affected by quality of diet. However, lambs of H-H and L-H sequences had a higher increase in HW during post-weaning period compared with lambs of H-L and L-L sequences. Quantity and quality of colostrum was not influenced by pre-pubertal plane of nutrition (P>0.05). Based on the results of current study the authors' suggestion is that skeletal compensatory growth during post-weaning period can compensate losses caused by poor nutrition during pre-weaning period. And also, the results indicated that skeletal size is a better indication for first-lactation colostrum yield than body weight (BW). [ABSTRACT FROM AUTHOR]

Local fat-tailed and imported thin-tailed sheep breeds are used for lamb production in hot arid zones. These animals are exposed to an extended summer (seven months) and shorter autumn, winter and spring seasons. The present study examined relative reproductive and lamb crop yields of low and high prolific Naeemi (N) and Border Leicester Merino (BLM) ewes under the intensive management system respectively. Mating systems used were N × N pure breeding and BLM × N rams in three-way crossing. The BLM ewes gave birth to 1.48 lambs per ewe per year as compared to 0.78 lambs per ewe per year for N. The weight of lambs born per ewe was 35% higher and weight weaned 45% higher for BLM ewes compared to N ewes. The lamb mortality was 10% with no significant differences between breeds. The parity significantly ( P ≤ 0.05) affected all reproductive traits in both the BLM and the N ewes, except the litter size in N, which was unaffected by parity. The N showed maximum reproduction at second parity (1.08 lambs/ewes) and BLM at third parity (1.63 lambs per ewe). While the lambs from BLM ewes’ first parity showed the highest mortality (21%), lambs from fifth parity showed the lowest mortality (4.5%). The weight of lambs born and weaned was significantly higher ( P ≤ 0.05) in autumn-mated than summer-mated BLM ewes. For BLM ewes, mortality was significantly higher ( P ≤ 0.05) in summer-born lambs than the lambs born in autumn, winter or spring. This study has demonstrated a moderate lifetime productivity of local N ewes and marked superiority of BLM to N for ewe reproduction and lamb crop yields under the intensive management system. [ABSTRACT FROM AUTHOR]

Lamb survival is an issue of high relevance to the Australian sheep industry, as lamb-survival rates have direct bearing on overall reproductive performance of the sheep, and also constitute a main concern from an animal welfare perspective (Mellor and Stafford 2004). Both genetic and management factors play an important role in this complex issue (Hinch and Brien 2014). Ewe nutrition is of particular relevance as the intrauterine growth conditions prepare the lamb for the crucial transition to life outside the uterus. Effects of body condition of the ewe during various stages of the pregnancy have been investigated in detail, yet much less is known about the critical role of micronutrient provision to the ewe. Although several risk factors for selenium (Se) and iodine (I) subclinical deficiencies exist for sheep on pasture in Australia, determining micronutrient status in sheep or pasture is not straightforward. Several studies have separately found effects of Se and I supplementation on lamb survival. Studies investigating the interaction of Se and I supplementation have been few but results have demonstrated an interaction between Se and I. With increased twinning rates as a result of increased selection of numbers of lambs weaned, nutritional demands during pregnancy across flocks are increasing, and effects of micronutrients on lamb health and survival have greater impact. New opportunities in nutritional research are encouraging new studies into the effects of Se and I supplementation on lamb survival. [ABSTRACT FROM AUTHOR]

Within triplet litters, light-born lambs are at greater risk of dying than heavier lambs in the first week of life. However, the implications of within-litter differences in sucking behaviour for milk intake and growth beyond the first week are unclear. We hypothesized that within litter, triplets born lightest would still be lightest at one to three weeks of age, that these lambs would have lower milk intake than heavier lambs, and that differences among lamb ranks (heaviest, medium, or lightest-born in litter) would be exacerbated in a competitive situation. Triplets in 10 litters were ranked according to birth weight and their sucking behaviour measured in two situations when they were 8–17 days old. In the morning session, undisturbed behaviour was recorded for 100 min, after which the lambs were separated from the ewe for four hours. They were then returned to the ewe and competitive sucking behaviour was recorded for 15 min. Measures of live weight and abdominal girth were taken before and after each observation period to estimate milk intake. At 8–17 days of age, the lightest-born lambs were still lightest but the medium and heavy born lambs no longer differed in live weight (P = 0.002). During the undisturbed period, heavy-born lambs sucked less often (P = 0.026) and for less time overall (P = 0.007) but gained similar live weight to their lighter siblings (P = 0.299), indicating that they were more efficient at extracting milk. In the competitive session, light-born lambs tended to gain less live weight (P = 0.086) and competed with the medium-born lambs for the teat not preferred by the heavy lambs (P = 0.0005). These observations indicate that heavy-born lambs are efficient feeders, that medium-born lambs work harder to achieve the same milk intake, and that light-born lambs achieve lower milk intakes, contributing to their persistently lower weight. Thus, management strategies such as fostering or supplemental feeding should be focussed on the lightest-born triplets. [ABSTRACT FROM AUTHOR]

Lamb mortality represents reproductive wastage and an animal welfare concern. While lambs are thought to be at a thermogenic advantage following birth in comparison to other species, death from exposure can still be a major contributor to lamb mortality, largely because of the inclement conditions often prevailing at lambing. For this reason, thermogenesis has been studied extensively in neonatal lambs. Heat is produced in the neonatal lamb by shivering and nonshivering thermogenesis. The latter is heat generated by metabolism of brown adipose tissue (BAT) found largely in the thorax and peri-renal areas of the newborn lamb. Brown adipose tissue differs from normal adipose tissue in that it contains densely packed mitochondria, a high cytochrome c content and a vast vascular network. Heat is generated in BAT by uncoupling of the proton conductance mechanism from ATP production, resulting in heat production instead of stored energy. The ability of lambs to resist cooling differs among individuals and this is likely to be due to both genetic and phenotypic factors. The heritability of cold resistance is moderate-to-high and polymorphic gene markers associated with energy homeostasis and cold-related mortality have been identified. Additionally, several aspects of the phenotype of the lamb have been associated with cold resistance. Most relate to properties of the coat, skin and bodyweight, the latter being particularly important, presumably through effects on surface area to volume ratios and subsequent heat loss. The ability of the neonate to achieve the transition from intra- to extra-uterine life has been termed physiological maturity and is associated with the ability to activate appropriate neuro-endocrinological and behavioural changes that are consistent with homeostasis of energy metabolism. Ways to alter physiological maturity of the lamb, such as nutrition, pharmacology and genetic selection, have been identified, and while these show promising results with regards to thermoregulation, a key limitation of their application has been the lack of a repeatable, representative model of neonatal cold stress. An estimation of the non-shivering component potential of a lamb's ability to thermoregulate can be derived from norepinephrine challenges, but more useful models of real-world cold stress are climate chambers or controlled water bath tests. Further use of repeatable test models such as these with appropriate neuroendocrine and metabolic metrics will identify key components and markers of physiological maturity associated with lamb thermogenesis and survival. [ABSTRACT FROM AUTHOR]

The objective of the present study was to examine the factors associated with the death of neonatal lambs. Postmortem autopsy data were collected from 3198 newborn lambs in the Sheep CRCs Information Nucleus Flock situated in various environments throughout southern Australia. The proportion dying by category from highest to lowest was starvation-mismothering (25%), stillbirth (21%), birth injury (18%), dystocia (9%), death in utero-prematurity (10%), predation (7%), cold exposure (5%), undiagnosed (4%), infection (1%) or misadventure (1%). Factors best explaining the probability of lambs falling into a death category included both birth type and birthweight for dystocia, stillbirth, starvation-mismothering and death in utero-prematurity. The probability of a lamb falling into any category was predicted at the mean birthweight, within birth type. Single-born lambs were more likely to die from dystocia and stillbirth, while twin lambs were more likely to die from birth injury, starvation-mismothering or from undiagnosed causes. Triplet lambs were more likely to die from starvation-mismothering or death in utero-prematurity. Sire type (Merino, maternal or terminal) did not affect the proportions of lambs within any category. The proportions lost to each cause of death were largely consistent among locations, despite the rate of death varying. Dystocia, stillbirth and birth injury, as evidenced by the presence of oedema around the head and neck or by lesions of the central nervous system, accounted for 48% of autopsied lambs. We conclude that for improvements to occur in the rates of lamb survival, the Australian sheep industry must focus on minimising losses due to dystocia, stillbirth, birth injury and starvation. [ABSTRACT FROM AUTHOR]

As causas de mortalidade perinatal em ovinos foram estudadas de março de 2002 a outubro 2004 em 27 fazendas da região semi-árida da Paraíba. De 90 cordeiros necropsiados, 41,1% morreram de infecções neonatais, 23,3% por malformações, 10% por inanição/hipotermia, 10% por distocia, 2,2% por predação e 4,4% foram abortos sem causa identificada. Em relação ao momento da morte, 4,4% dos cordeiros morreram antes do parto, 10% durante o parto, 30% no primeiro dia de vida, 20% entre o 2º e 5º dia e 35,6% entre o 4º e 28º dia após o parto. A assistência das ovelhas durante o parto, a desinfecção do umbigo dos cordeiros, a ingestão de colostro 2 a 6 horas após o parto, e a manutenção das ovelhas em locais adequados durante e após o parto contribuiriam para diminuir as mortes perinatais por distocia e infecções neonatais. A alta freqüência de malformações, em diferentes raças, sugere que esses defeitos sejam causados por uma planta tóxica. Os principais defeitos observados foram a flexão permanente dos membros anteriores, braquignatismo, fenda palatina e outras alterações dos ossos da cabeça. Recentemente foi demonstrado o efeito teratogênico de Mimosa tenuiflora ("jurema-preta"), uma planta muito comum na região semi-árida, nas áreas de caatinga, que aparentemente é responsável pelas malformações. Os cordeiros mortos por inanição/hipotermia tiveram baixo peso ao nascimento (1,37 ± 0,7kg) o que sugere que a principal causa dessas mortes é a deficiente nutrição da mãe durante o último terço da gestação. Considerando-se que na região nordeste, na maioria das fazendas, os carneiros permanecem com as ovelhas durante todo o ano, a adoção de uma estação de monta definida contribuiria para a diminuição da mortalidade perinatal.The causes of perinatal lamb mortality were studied, from March 2002 to October 2004, on 27 farms in the semiarid region of Paraíba, northeastern Brazil. In 90 lambs necropsied the following frequency of different causes of death was found: neonatal infections (41.1%), malformations (23.3%), dystocia (10%), starvation/hypothermia (10%), abortion (4.4%), and predation (2.2%). Regarding the time of death, 4.4% of the lambs died before parturition, 10% during parturition, 30% on the first day after parturition, 20% between the second and the third day, and 35.6% between the 4th and the 28th day after parturition. The assistance during parturition, umbilical disinfection of the neonates, colostrum ingestion between 2 and 6 hours after parturition, and keeping the ewes in healthy environmental conditions during and after parturition could improve lamb surviving. The high frequency of malformations in different breeds suggests that malformations are due to a toxic plant. The main defects were permanent flexure of the front legs, brachygnathia, cleft palate, and other head malformations. In a recent report the authors demonstrated the teratogenic effects of Mimosa tenuiflora, a very common plant in the semiarid region, which is probably the cause of those malformations. Lambs which died due to starvation/hypothermia and had low birth weight (1.37 ± 0.70kg), suggesting that a better nutrition of the ewe during the last trimester of gestation is a way to control this cause of lamb mortality. Considering that in the northeastern region, in most farms, the rams stay with the ewes during the whole year, the adoption of a breeding season would help to control the different causes of perinatal lamb mortality.