Survival Rate Of Lambs Research Articles

Genome-wide selection reveals candidate genes associated with multiple teats in Hu sheep

Increasing the number of teats in sheep helps to improve the survival rate of sheep lambs after birth. In order to analyze the candidate genes related to the formation of multiple teats in Hu sheep, the present study was conducted to investigate the genetic pattern of multiple teats in Hu sheep. In this study, based on genome-wide data from 157 Hu sheep, Fst, xp-EHH, Pi and iHS signaling were performed, and the top 5% signal regions of each analyzed result were annotated based on the Oar_v4.0 for sheep. The results show that a total of 142 SNP loci were selected. We found that PTPRG, TMEM117 and LRP1B genes were closely associated with polypodium formation in Hu sheep, in addition, among the candidate genes related to polypodium we found genes such as TMEM117, SLC25A21 and NCKAP5 related to milk traits. The present study screened out candidate genes for the formation of multiple teats at the genomic level in Hu sheep.

On-farm performance evaluation of indigenous sheep in the Gedeo zone, Southern Ethiopia

ABSTRACT This study was conducted to identify the productive and reproductive performance of sheep in the Gedeo zone. Flock of 50 households was randomly selected for a household survey. A total of 189 lambs’ growth data and reproductive traits from 125 ewes were collected. A general linear model was employed for the analysis. Sheep flock size shows (8.6 ± 0.11) a significant difference (P < 0.05) among age categories. Weight at birth (3.01 ± 0.3 kg), weaning (14.2 ± 0.9 kg) and six months (22.4 ± 1.1) of lambs were significant (P < 0.01) among parties, birth type, lamb sex and birth season. Body size and growth rate were important traits for breeding sheep selection. The average age at first lambing and lambing interval was 12.3 ± 0.12 and 7.7 ± 0.06, respectively. Other reproductive traits, such as fertility rate (76.7%), litter size (1.51), weaning percentage (81.6%) and lamb survival rate (86.2%), were observed. In conclusion: parity, birth type, lamb sex and birth season are important sources of variation in sheep growth performance that were considered fixed effects during the analysis. Thus, as policy direction, genetic improvement combined with nutrition, health and participatory breeding would contribute to sheep genetic improvement that should be given proper attention.

FecB Was Associated with Litter Size and Follows Mendel's Laws of Inheritance When It Transited to Next Generation in Suhu Meat Sheep Breeding Population.

In order to investigate the effect of FecB on litter size and growth and development traits of Suhu meat sheep and the inheritance patterns of FecB between parents and offspring in the population. In this experiment, 2241 sheep from the Suhu meat sheep population were tested for FecB using capillary electrophoresis. We combined the lambing records of 473 ewes, the growth trait records of 881 sheep at both the birth and weaning (2-month-old) stages, and the complete genealogical records of 643 lambs to analysis the distribution of FecB in the Suhu meat sheep breeding population, its effect on litter size of ewes, growth and development of lambs, and the inheritance patterns of FecB. The results showed that there were three genotypes of FecB in the Suhu meat sheep population, namely the AA genotype, AG genotype, and GG genotype. FecB in this population has a moderate polymorphism (0.25 < PIC < 0.5), and deviates from Hardy-Weinberg disequilibrium (p < 0.05). The litter size of GG genotype ewes was significantly higher than that with the AG and AA genotypes (p < 0.01). A Chi-square test showed that the inheritance patterns of FecB follows Mendel's Laws of Inheritance (p > 0.05). An association analysis of different genotypes of FecB with body weight and body size of Suhu meat sheep at birth and weaning revealed that FecB adversely affects the early growth and development of Suhu meat sheep. In summary, FecB can improve the litter size of ewes but it has negative effects on the early growth and survival rate of lambs in sheep. Therefore, FecB test results and feeding management measures should be comprehensively applied to improve the reproductive performance of ewes, the survival rate and production performance of lambs in sheep production, and thus improve the economic benefits of sheep farms.

Growth performance and survival rates of Desert lambs under grazing condition in North Kordofan State, Sudan

Growth performance and survival rates of Desert lambs under grazing condition in North Kordofan State, Sudan

The effects of maternal calcium status during late gestation on lamb growth and survival in twin-bearing Merino ewes grazing pasture.

Our project aimed to investigate whether low maternal calcium status during late gestation decreased weight, growth and survival of lambs born to twin-bearing Merino ewes grazing pasture. On day 130 of gestation, approximately a 10 mL blood sample was collected from 108 twin-bearing Merino ewes. Blood pH and calcium ion concentration were measured in whole blood and serum was analysed for calcium, magnesium, phosphate, beta hydroxy butyrate, non-esterified fatty acids and cholesterol. Six to 18 h after birth and at 49 days of age, lamb live weight was recorded. Ewe serum calcium level at day 130 of gestation were divided into tertiles (1.58-2.13, 2.14-2.30, and 2.31-2.99 mmol/L) with ewes classified as either Low, Med or High (n = 36 per group). A general linear mixed model was used to analyse the data. Survival to 1, 2, 3 and 7 days of age was lower for lambs born to ewes in the Low calcium group compared with those born in the Med and High calcium groups (P < 0.05). At day 49 of age, lamb survival tended to be lower for lambs in the Low (73.6%) compared with Med (86.8%) and High (85.3%) calcium groups (P < 0.1). There were no differences in lamb body weight (P > 0.05). Calcium levels of ewes in the Low calcium group were, on average, indicative of subclinical hypocalcaemia, with this group of ewes also having the lowest lamb survival rate, suggesting that maternal subclinical hypocalcaemia reduces lamb survival. Further studies, particularly on improving maternal calcium levels, are warranted.

A Survey of the Current Farming Practices and Perceptions on Adopting Orphan Lambs in the United Kingdom: How Do “Ewe” Do It?

Fostering orphan lambs is common in the United Kingdom and therefore it is important to understand more about these practices to support sustainable sheep farming. Data were collected on current approaches to adopting lambs and the perceived success of these methods using an online survey. Of the 543 responses, 93.7% reported that they attempt to foster lambs with the most common reasons reported as high litter size and ewes with little to no milk production. Although respondents reported that the best method was wet, non-tethering techniques, the most commonly used methods were tethered (restraint of the ewe) followed by untethered (birth fluids and skins from dead lambs). Other techniques included disguising the smell of the lamb. There was a significant association between increased flock size and using tethered methods as well as increased numbers of methods used and orphan lambs (p ≤ 0.001). However, larger flocks were also associated with decreased lamb survival rates (p ≤ 0.001). Time and patience were mentioned as important tips for fostering and could be a factor in which method is chosen. Research on the impacts of these methods is warranted as some may be stressful, affecting long-term flock performance, survival, welfare and health.

Are alpacas especially protective of lambs? An insight into alpaca guardian behaviour towards sheep using an arena preference test

Alpacas are increasingly used as a guardian species in Australian sheep flocks in an effort to improve lamb survival rates. Yet little is documented about the role and mechanisms of alpaca guarding behaviours within this environment. The first phase of this study, evaluated the temperament of 44 alpacas by assessing their behaviour when individuals were separated from herd mates. Tests included agitation while in an isolation enclosure, flight speed and behaviour in observation arena tests. The second phase of the study evaluated alpaca responses to different auditory, olfactory and visual cues representative of young lambs, adult sheep (ewes) and other novel stimuli. Alpacas (n = 24) which had not previously been exposed to sheep were individually presented with stimuli in a test arena. Behavioural responses were recorded over 2 min and analysed to compare differences between stimuli type (lamb/ewe/other) and stimuli cue form (live animal/auditory only/olfactory only/visual only). In phase one of this study alpacas exhibited little agitation while retained in an isolation enclosure with 67% of animals demonstrating a low agitation score. Females appeared to have a more ‘reactive’ temperament than males, exhibiting significantly faster flight speeds (P < 0.01) and more frequent pacing behaviour (P < 0.01) in the observational pen. In the arena test both male (n = 12) and female (n = 12) alpacas consistently exhibited greater attraction towards the lamb stimuli type (for all cue forms) compared to the ewe and other atypical stimuli (P < 0.05 for all comparisons). Alpacas showed the greatest attraction towards the live lamb compared to visual (P < 0.01), auditory (P < 0.01) and olfactory lamb cues (P < 0.001). Both male and female alpacas demonstrated similar response times and there were no significant differences between alpaca sex in the total time spent reacting to the lamb and ewe stimuli. This study demonstrates that alpacas exhibit a greater attraction towards or interest in young vulnerable animals such as lambs and supports the available anecdotal evidence that the use of alpacas as livestock guardians may be useful in improving lamb survival rates.

Mitigating the impacts of weather on lamb survival in Southern New Zealand

Increased fecundity and improved feed management have doubled the number of lambs born in any threeday period in spring since 1990. Four farmer catchment groups were engaged to investigate options that farmers may use to reduce the impacts of weather at lambingtime. After workshops identified potential mitigations, a lamb survival model was developed using data from the literature. This was applied at daily time steps to weather data over a 20-year period from 1980-1999, with chosen mitigations added to investigate their impact. Direct intervention by improving pre-lambing ewe nutrition increased live lambs by 7-8% (P&lt;0.05). Policy development strategies to provide shelter increased live lambs by 8 and 17% with reductions in wind speed of 50 and 100% respectively (P&lt;0.05). These results were consistent across all environments tested. Increasing fecundity increased the net number of lambs at docking, though also resulted in a greater number of lamb losses. Spreading risk by spreading lambing did not alter the net long-term lamb survival rate. Provision of shelter, both before and during lambing, and ensuring adequate pre-laming ewe nutrition were most effective at consistently improving lamb survival in all the environments tested.

Effects of non-genetic factors on growth traits and survival rate in Karacabey Merino lambs.

This study was conducted with the aim of determining the growth characteristics and survival rate of Karacabey Merino lambs, as well as the non-genetic factors affecting these traits. The study included data from a total of 17659 lambs and 12263 ewes raised in 30 herds between the years 2011 and 2016 as part of the National Sheep and Goat Improvement Project. The average birth weight of the lambs was determined as 3.73±0.05 kg, the average 45th day live weight was 18.43±0.58 kg, the average weaning (average 91.8 days) weight was 31.83±0.24 kg, and the average daily live weight gain until weaning was 289.1±3.91 g. The average survival rate of lambs at weaning was calculated to be 95.67% ± 1.15. The effects of the factors herd, birth year, birth type, birth season and sex were found significant for all traits (p<0.01). It was established that the mortality rate in lambs in large herds was higher during 6 years in which the project was carried out. Due to the high twinning rate in large herds, the number of lambs per worker is increased, and as a result, they cannot be adequately cared for. For this reason, large farms may be encouraged to increase workmanship services in addition to being provided with protective health practices for lambs throughout the birth period. On the other hand, it was determined that the twinning rate was low in small farms. On farms with fewer sheep populations, it may be advised to flush or administer exogenous hormone treatments to ewes in order to increase fertility and help them bear twins.

Rupture of the Prepubic Tendon in a Quadruplet Pregnant Romanov Ewe

A case of prepubic tendon rupture in a Romanov ewe in which four live lambs were removed by cesarean section is presented. A three-year-old ewe, on the 142±3 days of the second gestation was brought to the Siirt University Animal Health Application and Research Center with a sudden downward expansion of the abdomen during the last one day. When ewe was examined reluctance to locomotion, mild depression, tachycardia, tachypnea and abdominal peculiar enlargement on the left side more than right side were noticed. Because of this case was detected early the general condition was not so bad and clinical examination revealed that swelling was non-painful and non-edematous. Ultrasonography was performed to detect viability of the fetuses, and to eliminate possibility of hernia of the abdominal muscles. Based on anamnesis, abdominal palpation, and clinical examination, this case was diagnosed with prepubic tendon rupture. The prognosis of saving the lives of ewe and fetuses depends on successfully handling all aspects of the case in the last period of pregnancy. Although it is not possible to repair the abdominal integrity surgically in cases of prepubic tendon rupture in the ewe, a planned cesarean operation is indicated to increase the survival rates of both ewe and lambs.

Ewes with higher embryo survival rear lambs that grow faster.

A key economic driver of a meat producing sheep flock is the total kilograms of lamb liveweight at weaning per ewe exposed to the ram. Optimization of key reproductive steps is required to achieve peak performance of a sheep flock. The goal of this paper was to use more than 56,000 records from a commercial flock to investigate the key reproductive steps affecting flock reproductive performance. We also applied a maximum-likelihood based technique to predict the embryo survival and ovulation rate for daughters of individual sires based on measurements of the number of fetuses at midpregnancy (detected by ultrasound-scanning). The model was used to determine how changes in premating liveweight, age, predicted ovulation rate, embryo survival, number of fetuses at midpregnancy, lamb survival, and lamb growth rate affect the total lamb liveweight at weaning per ewe exposed to the ram in the flock. The data from the commercial flock was also used to investigate the role of ewe age and premating liveweight on each reproductive step. Sensitivity analyses were performed to identify the key reproductive steps affecting flock reproductive performance. The elasticity for embryo survival was 80% of that for lamb survival. There was also significant between sire variance in the estimates of ovulation rate and embryo survival. The reproductive performance of daughters of sires with high (top 50%) and low (bottom 50%) embryo survival was investigated. Embryo survival was 0.88 in the high group and 0.82 in the low group (a 6% reduction in embryo survival). The expected total weight of lambs weaned per ewe exposed to the ram was 42 kg in the high embryo survival group and 37 kg in the low embryo survival group (a 12% reduction in the total weight of lambs weaned per ewe exposed to the ram). The proportion of twin litters was 70% in the high group and 60% in the low group, highlighting the potential importance of embryo survival for the rate of twinning in flocks with ovulation rates greater than two ova. Although lamb survival was similar between the high and low embryo survival groups, lamb growth was reduced by 10% in the low embryo survival group for the same litter size (P < 0.001). This novel positive phenotypic association between embryo survival and lamb growth rate can potentially be exploited to improve flock performance.

Litter size, litter weight, and lamb survivability of Doyogena sheep managed under community-based breeding program in Ethiopia

Increasing litter size and weight during the marketing time by decreasing mortality among lambs per ewe is the objective of the community-based breeding program (CBBP). This study aims to find out litter size, litter weight per ewe, and preweaning lamb mortality of Doyogena sheep managed under CBBP. The study analyzed the data records of 4530 animals for 8 years from 2013 to 2020. A logistic regression procedure was used to analyze pre-weaning lamb survival rates. Results showed that the overall least-squares means of litter size at birth (LSB), litter size at weaning (LSW), total litter weight at birth (TLWB), and total litter weight at weaning (TLWW) were 1.57 ± 0.02 lambs, 1.50 ± 0.02 lambs, 5.24 ± 0.09 kg, and 24.14 ± 0.69 kg respectively. The incidence of pre-weaning lamb mortality was 4.72%. Year and breeder cooperative vary were observed for pre-weaning lamb losses. Females had lower odds of survival as compared to males. Odds of survival were low for triplets, quadruplets, and low birth weight (≤2 kg) born lambs. The ongoing selection program which aims to improve reproductive and growth performance had a positive influence on the survival rate of lambs. Improvement of the environment in the flock, special care for multiple-born and care for small lambs would lead to further lamb survival improvements.

Lower Reproductive Rate and Lamb Survival Contribute to Lower Lamb Marking Rate in Maiden Ewes Compared to Multiparous Ewes.

Simple SummaryThe reproductive performance of ewes in their first breeding season (maiden ewes) can be poorer and more variable than at subsequent breeding seasons. However, the extent and causes of the poorer reproductive performance of maiden ewes on Australian sheep farms are not well understood. We used a survey of Australian sheep farmers to compare the reproductive performance of maiden ewes in their first breeding season to multiparous ewes (ewes that have been bred two or more times) on the same farms. We found that the difference in lamb marking rate between non-Merino ewe lambs and multiparous ewes on the same farm was 58%, and for maiden Merino two-tooth ewes, the difference in marking rate compared to multiparous ewes was 22% lower. Poorer reproduction in maiden ewes was due to a combination of poorer reproductive success to mid-pregnancy (reproductive rate), plus poorer survival of lambs between mid-pregnancy and lamb marking. Reproductive performance for maiden Merino two-tooth ewes was correlated with multiparous ewes on the same farm, whereas the reproductive performance of non-Merino ewe lambs was more variable and not associated with the reproductive performance of their multiparous counterparts. The reproductive efficiency of maiden ewes could be improved by addressing factors that improve the reproductive rate and lamb survival between scanning and lamb marking.Suboptimal reproductive performance of maiden (primiparous) ewes remains a source of inefficiency for the Australian sheep industry. However, the extent and causes of the poorer reproductive performance of maiden ewes on Australian sheep farms are not well understood. Here, we show the reproductive performance of maiden ewes relative to their multiparous counterparts on the same farms across Australia using a cohort survey. The difference in marking rate for non-Merino maiden ewe lambs compared to multiparous ewes was 58% (74 vs. 132%; p < 0.001), and this was attributable to a 50% difference in reproductive rate (109 vs. 159%; p < 0.001) and 16% difference in lamb survival to marking (67 vs. 83%; p < 0.001). The difference in marking rate for maiden Merino two-tooth ewes lambing at approximately 2 years-of-age compared to mature multiparous ewes was 22% (80 vs. 102%; p < 0.001) and this was attributable to a 24% difference in reproductive rate (108 vs. 132%; p < 0.001) and 3% difference for lamb survival (75 vs. 78%; p < 0.05). Positive correlations for reproduction traits (reproductive rate, lamb survival and marking rate) between maidens and multiparous ewes were observed for maiden Merino two-tooth ewes (p < 0.001), but these correlations were weak or non-existent for non-Merino ewe lambs. Strategies to improve both reproductive rate and lamb survival can address the poorer and more variable reproductive performance of maiden ewes.

Evaluation of genotype and nongenetic effects on some production traits: Comparison of Akkaraman and Bafra × Akkaraman B&lt;sub&gt;1&lt;/sub&gt; sheep genotypes

The purposes of this study were to evaluate genotype and some environmental effects on the reproductive and milk yield traits of sheep, and vitality and growth traits of lambs, and to compare the difference between Akkaraman (AKK) and Bafra × AKK B$_{1}$ (BA B$_{1}$: Bafra sires crossed BA F$_{1}$ ewes) genotypes in terms of these characters. Data were collected from 71 ewes for fertility traits and 37 ewes for milk yields in each genotype. Growth traits and survival rates of lambs were evaluated using 55 AKK and 56 BA B$_{1}$ lambs. AKK and BA B$_{1}$ ewes had 87.32% and 92.96% for lambing rate (p > 0.05), 125.35% and 161.97% for lamb production (p = 0.005), 1.45 and 1.74 for litter size (p = 0.072), respectively. Lactation milk yields and lactation lengths of those were determined as 109.46 ± 6.61 and 124.55 ± 7.26 kg (p > 0.05), and 155.76 ± 2.36 and 161.51 ± 2.43 days (p > 0.05), respectively. The survival rates and body weights of their lambs at weaning (90$^{th}$ day) were 87.27% and 87.50% (p > 0.05), and 27.77 ± 0.59 and 21.97 ± 0.59 kg (p = 0.000), respectively. In conclusion, the age of the dam affected the reproductive and milk yield traits, birth type affected the growth, and sex affected the survival rate and growth traits. Regarding the genotype effect, the BA BH$_{1}$ genotype had better reproductive and lactation milk yield, lower growth performance than those of the AKK genotype, and a similar survival rate to the AKK genotype.

Melatonin treatment during late gestation of undernourished ewes: lamb body temperature and mother–young behaviours after birth

Context In extensive grazing sheep systems, pregnant ewes undergo periods of undernutrition because gestation coincides with winter when natural pasture is of lowest quantity and poorest quality. The lamb’s weight and thermoregulatory capacity, and the ewe–lamb bond at birth, may be compromised. Maternal melatonin treatment during gestation may reverse these effects. Aim The aim was to determine the effects of melatonin treatment of single-lambing, undernourished ewes during the last third of gestation on lamb birthweights and body temperatures, and on ewe–lamb interactive behaviour after birth. Methods At Day 100 of gestation, 39 single-bearing ewes received a subcutaneous melatonin implant, and 54 ewes served as controls with no implant. Throughout gestation, the ewes remained under extensive conditions grazing on natural pasture. Measurements were made of lamb birthweight, body temperatures (surface temperature by infrared thermography and rectal temperature), and ewe–lamb behaviours during a handling test at 6–17 h after lambing. Key results There was no effect of melatonin treatment on lamb birthweight or rectal temperature, or on ewe–lamb interaction behaviours. Hip minimum surface temperature was greater in lambs from melatonin-treated ewes than lambs from control ewes (21.2°C ± 0.9°C vs 18.8°C ± 0.8°C; P = 0.05), and there was a similar trend for hip mean surface temperature (24.6°C ± 0.9°C vs 22.3°C ± 0.7°C; P = 0.06). Rump surface temperatures were greater in male than female lambs: maximum (27.9°C ± 1.2°C vs 22.9°C ± 1.2°C; P = 0.01), minimum (22.2°C ± 1.5°C vs 16.7°C ± 1.5°C; P = 0.02) and mean (25.4°C ± 1.3°C vs 20.5°C ± 1.3°C; P = 0.02). Conclusion Melatonin treatment during the last third of ewe pregnancy slightly enhanced the surface temperature of lambs at birth but did not influence ewe–lamb interaction behaviour after birth (i.e. after establishment of the ewe–lamb bond). Implications Further study in more depth is warranted into the possible effects of maternal supplementation with commercial melatonin implants on lamb development, thermoregulatory capacity, behaviour and survival rates in extensive grazing systems, including the effect on ewe–lamb behaviours immediately after birth for both singletons and twins.

The Number of Offspring Weaned from Ewe Lambs Is Affected Differently by Liveweight and Age at Breeding.

Simple SummaryEwe lambs can reach puberty and conceive at 7 to 10 months of age and those that are heavier at breeding are consistently more fertile. The aim of this research was to quantify the separate effects of age and liveweight at the start of breeding on the components of weaning rate. The analysis of data from more than 11,500 maternal composite ewe lambs indicated that ewe lambs that were heavier at the start of the breeding period weaned more offspring than lighter ewes, but if ewe lambs reached 45 kg their weaning rate was within 5% of their maximum for a given age. By contrast, the effects of age at breeding on weaning rate was linear and increased by 0.4% per day. Within the range from 35 to 45 kg liveweight and 6 to 9 months of age, a 1-kg increase in the liveweight at the start of breeding had the equivalent effect on weaning rate as an extra 7 days of age at the start of breeding. This understanding of the trade-off between age and liveweight at breeding will assist farmers to optimize the management and reproductive performance of ewe lambs.In this paper, we tested the hypothesis that ewe lambs that are heavier and older at breeding will wean more offspring, due to increased reproductive rate and offspring survival and lower maternal mortality. To test this hypothesis, we analyzed data from more than 11,500 maternal composite ewe lambs collected over eight years. The ewe lambs had full pedigree records including birth type, age and liveweight at breeding plus records of the birthweight and survival of their offspring and the dam. The average liveweight and age at breeding was 40.2 kg and 228 days. The reproductive rate and weaning rate responses to liveweight at breeding were curvilinear (p < 0.001), and if ewe lambs achieved 45 kg by the start of breeding, their reproductive rate and weaning rate were within 5% of their maximum. By contrast, the effects of age at breeding on weaning rate was linear and increased by 0.4% per day, despite a quadratic (p < 0.01) effect of age at breeding on reproductive rate which increased only marginally when ewe lambs were older than 8 months at breeding. Increasing liveweight (p < 0.05) or age (p < 0.001) at breeding increased survival of their offspring, however an extra 10 kg of liveweight or 30 days of age at breeding increased offspring survival by less than 5%. Both liveweight (p < 0.001) and age (p < 0.01) at breeding also influenced survival of the ewe lamb dam but survival rates exceeded 95% across the range in liveweights from 30 to 55 kg and ages from 6 to 9 months. This understanding of the trade-off between age and liveweight at breeding will assist farmers to optimize the management of their ewe lambs, given the earlier they can be bred successfully the easier they can be integrated with the breeding of the adult ewe flock the following year.

Effects of parity, litter size and lamb sex on maternal behavior of small Tail Han sheep and their neuroendocrine mechanisms

• Parity, litter size, and lamb sex affect the maternal behavior of Small-tailed Han sheep. • Multiparous ewes, twin-lamb ewes, ewes with female lambs seemed to have better maternal behavior. • Our findings provide a theoretical basis for the further improving the survival rate and welfare of lambs. The high mortality of lambs has always restricted the development of Small-tailed Han sheep breeding, causing serious economic losses and welfare problems in the sheep breeding industry. Stable and good-quality maternal behavior is critical for the survival of offspring, and given the importance of maternal behavior on early lamb survival, improving maternal behavior in ewes seems to be an effective way to improve lamb survival rates. Thus, exploring the factors that influence maternal behavior is a good place to begin. Therefore, in this study, we investigated the effects of parity, litter size, and lamb sex on the maternal behavior of Small-tailed Han sheep. The neuroendocrine mechanism involved in regulating maternal behavior were also analyzed. Primiparous and multiparous ewes, ewes with different litter sizes, and ewes with different lamb sexes were selected, and their maternal behaviors, including lactating, grooming, following, looking, and udder refusal, were observed and analyzed using scanning and sampling methods during the first 7 days after parturition. The lambs’ body weights were recorded for the first 35 days after birth. The concentrations of estradiol, oxytocin, norepinephrine, dopamine, NO, and γ-aminobutyric acid (GABA) of ewes were measured with ELISA kits for 35 days after parturition. The results showed that the looking and udder refusal behavior of multiparous ewes was significantly lower than primiparous ewes (P = 0.004 and P = 0.036). The grooming behavior was significantly higher in both primiparous and multiparous ewes at Day 0 than at Day 1∼7 after parturition (P < 0.05). Ewes with two offspring expressed significantly more lactating behavior than ewes with single lambs in the first 3 days after parturition (P < 0.05). The looking behavior was significantly lower in twin-lambing ewes than in single-lambing ewes at Day 7 postpartum (P = 0.031). The grooming behavior was significantly higher in both single and twin lambing ewes at Day 0 post parturition than at Day 1∼7 post parturition (P < 0.05). Lactation behavior was significantly higher in ewes producing female lambs than in ewes producing male lambs at Day 2 after parturition (P = 0.018). When a female lamb was born, the looking behavior of ewes was significantly higher than ewes with male lambs on Day 3 after parturition (P = 0.01). The grooming behavior and the udder refusal behavior of male lambing ewes were significantly higher at the Day 0 after parturition than at the Day1∼7 after parturition, similar temporal trend was observed in female lambing ewes (P < 0.05). The body weight of lambs was higher in the multiparous ewes group. This was especially significant at Day 0 and Day3 after birth (P = 0.045 and P = 0.007). Single lambs seemed to have higher birth weights than twin lambs; however, the differences were not significant (P > 0.05). Male lambs were significantly heavier than female lambs at Day 0 and Day 7 after birth (P = 0.044 and P = 0.048); thereafter, the lambs of the two groups showed no significant difference in body weight. The level of oxytocin in multiparous ewes was significantly higher than that of primiparous ewes (P < 0.05). The levels of oxytocin, norepinephrine, dopamine, NO, and GABA in ewes with twin lambs were significantly higher than those of ewes with single lambs (P < 0.05). Ewes with female lambs had a significantly higher level of oxytocin than ewes with male lambs at Day 0 (P = 0.024). In conclusion, multiparous ewes exhibited better quality maternal behavior than primiparous ewes, and this was associated with the level of oxytocin in the serum. Ewes with twin lambs exhibited better quality maternal behaviors than the single lamb group, and this was related to the levels of oxytocin, norepinephrine, dopamine, NO, and GABA. Oxytocin was also found to be associated with the improved ewe maternal behavior with female lambs. Altogether, ewes with better maternal behavior have a higher level of oxytocin and noradrenaline. Moreover, the expression of maternal behavior in ewes is positively correlated with lamb weight. Our findings contribute the understanding of the neuroendocrine mechanisms of maternal behavior in Small-tailed Han sheep and provide a theoretical basis for the further exploration of artificial methods to improve ewe maternal behavior, and ultimately improve the survival rate and welfare of lambs.

The role of reproductive loss on flock performance: a comparison of nine industry flocks.

The reproductive performance of a sheep flock is dependent on a multitude of complex interacting factors. Attaining optimal flock performance requires information about how the reproductive steps are linked and relate to readily available measurements of the state of the flock. The goal was to use data from nine commercial flocks (greater than 300,000 records) to investigate and model the key reproductive steps affecting flock reproductive performance. We also developed a maximum-likelihood based methodology to predict flock ovulation rate based on measurements of the number of fetuses at mid-pregnancy (detected by ultrasound-scanning). The model was used to determine how changes in premating liveweight, age, predicted ovulation rate, number of fetuses at mid-pregnancy, lamb survival and lamb growth rate affect the total lamb liveweight at weaning per ewe exposed to the ram in each flock. The data from the commercial flocks were also used to investigate the role of ewe age and premating liveweight on each reproductive step. Sensitivity analyses were conducted to identify the key reproductive steps affecting flock reproductive performance, with a focus on understanding how these steps vary between flocks. The elasticity for embryo survival was 60% of that for lamb survival for these flocks and the elasticities for ovulation rate were highly variable between flocks (0.16 to 0.50 for mature ewes). This indicates that ovulation rate was near-optimal for some flocks, whereas there was potential to significantly improve flock performance in suboptimal flocks. The elasticity for ewe premating liveweight was highly variable between flocks (−0.03 to 0.84 for mature ewes and −0.18 to 1.39 for ewe lambs), indicating that premating liveweight ranged from optimal to suboptimal between flocks. For these suboptimal farms, the opportunity exists to increase flock performance through improved management of ewe premating liveweight. Reproductive loss was significantly greater in ewe lambs than mature ewes, although the difference is dependent on the stage of reproduction and flock. Predicted ovulation rate was 25% lower for ewe lambs and there was a 30% relative decrease in the predicted embryo survival probability from ovulation to scanning for ewe lambs. There was a 10% relative decrease in lamb survival probability from birth to weaning for ewe lambs and lamb growth rate was 25% lower for ewe lambs.

PSXI-13 Effect of performance indicators, food expenses and interest rate on lamb production cost

Abstract This study aimed at comparing the influence of zootechnical performance and main cost items over the total production cost of lambs. A representative production system of São José do Rio Preto region, Brazil, designed in a panel meeting, was used as a study basis. We calculated lamb production costs, including variable costs, fixed costs, and income of factors, using the data from December 2019. We then estimated elasticities for the variables: feed expense, interest rate, carcass yield, lamb survival rate, and fertility rate. This way we compared the variation in total cost per year and per carcass caused by increases of 1% in each of the considered variables. In the base scenario, production costs per year and unit were, respectively, US$ 33,367.34 and US$ 4.81. Feed expenses, annual interest rate, mean carcass yield, lamb survival rate, and fertility rate were, respectively, US$ 22,316.74, 4.50%, 48.00%, 88.00%, and 85.00%. Regarding annual cost, changing each variable caused variations of +0.67%, +0.05%, 0.00%, +0.33% and +0.33%. Concerning cost per unit, the variations were +0.76%, +0.07%, -0.98%, -0.61% and -0.64%, respectively. Increasing lamb survival and fertility rates were also effective strategies to lower unitary cost. The cost component with feed represented 66.88% of the total production cost, but measures to reduce feed costs must be well conducted to not affect the zootechnical performance of the animals. Farmers must consider cost per unit when thinking about lowering production costs, instead of the annual cost. Increasing lamb carcass yield had a greater impact on reducing unitary cost than cutting feed expenses. Improving performance indicators demand good nutritional status for lambs and ewes, and cutting off feed expenses may have deleterious effects on animal performance, therefore increasing cost. Elasticity analysis is a useful tool to calculate such trade-offs at the farm level.

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

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