Age Of Ewe Research Articles

The Effect of Ewe's Age and The First Birth On Sex Lamb , Type of Birth , Litter Size And the Lamb's Weight at Birth and some Genetic Parameters

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Characterization of a novel ovine model of hypertensive heart failure with preserved ejection fraction.

The lack of animal models that accurately represent heart failure with preserved ejection fraction (HFpEF) has been a major barrier to the mechanistic understanding and development of effective therapies for this prevalent and debilitating syndrome characterized by multisystem impairments. Herein, we describe the development and characterization of a novel large animal model of HFpEF in older, female sheep with chronic 2-kidney, 1-clip hypertension. At 6-wk post unilateral renal artery clipping, hypertensive HFpEF sheep had higher mean arterial pressure compared with similarly aged ewes without unilateral renal artery clipping (mean arterial pressure = 112.7 ± 15.9 vs. 76.0 ± 10.1 mmHg, P < 0.0001). The hypertensive HFpEF sheep were characterized by 1) echocardiographic evidence of diastolic dysfunction (lateral e' = 0.11 ± 0.02 vs. 0.14 ± 0.04 m/s, P = 0.011; lateral E/e' = 4.25 ± 0.77 vs. 3.63 ± 0.54, P = 0.028) and concentric left ventricular hypertrophy without overt systolic impairment, 2) elevated directly measured left ventricular end-diastolic pressure (13 ± 5 vs. 0.5 ± 1 mmHg, P = 2.1 × 10-6), and 3) normal directly measured cardiac output. Crucially, these hypertensive HFpEF sheep had impaired exercise capacity as demonstrated by their 1) attenuated cardiac output (P = 0.001), 2) augmented pulmonary capillary wedge pressure (P = 0.026), and 3) attenuated hindlimb blood flow (P = 3.4 × 10-4) responses, during graded treadmill exercise testing. In addition, exercise renal blood flow responses were also altered. Collectively, our data indicates that this novel ovine model of HFpEF may be a useful translational research tool because it exhibits similar and clinically relevant impairments as that of patients with HFpEF.NEW & NOTEWORTHY We show that older, female sheep with chronic 2-kidney, 1-clip hypertension have similar cardiac and noncardiac exercise hemodynamic abnormalities as patients with HFpEF. This clinically relevant, translatable, and novel large animal model of HFpEF may be useful for elucidating mechanisms and developing treatments for this increasingly common syndrome with few clinically impactful therapies.

Effect of age of Awassi ewes crossed with Naimi rams on some growth characteristics and litter size

The study focused on Awassi ewes crossed with Naimi rams. Ewes weight and age were closely related to their productivity, especially on female reproductive performance, therefore this research studied the effect of ewes age to their weight, as well as the effect of the ewes age on the weight of their lambs at birth, at one month, 4 month and to their sex and fertility. In the Awassi ewes used in this study, mature body size was attained at the age of 4 then it started to decline. At lambing, the lambs whose mothers were at the age of 5 years outperformed the rest of the age groups of their mothers, and at one month, the lambs whose mothers were at the age of 3 years outperformed (p ≤0.05) the rest of the age groups of their mothers. The weight of the lambs at weaning (4 months of age) showed the highest in the lambs whose mothers were 3 to 4 years old. The largest number of male lambs were obtained from ewes aged 2.5 and 3 years (75 and 88.9% respectively). Singleton births were 100% for all ewe ages, except for the ewes aged 2.5 and 3 years (40 and 20%, respectively). The highest number of twin births (80%) (p ≤0.05) was obtained in lambs whose mothers were 3 years old, while the highest litter size was 1.8.

Animal performance over 16 years after implementing a lucerne grazing system on Bog Roy Station - a case study

In 2023, the animal performance data for Bog Roy station show 151 t weaned lamb is being produced from 4272 ewes plus 9.0 t from hogget lambs. The ability to mate merino hoggets has resulted from increased feed supply that means mixed age ewes are now consistently averaging 65.6±1.17 kg/hd at mating (2019-2023). This has enabled an emphasis on two-tooth weight at mating, which has also increased 0.74±0.14 kg/hd/yr (R2 = 0.64) from 52 kg/hd in 2012 to 61 kg/hd in 2023. Consequently, scanning is consistently ~167±1.59% for the mixed age ewes (2012-2023) and increased from 113% (2008) to 154% (2023) in the two-tooths. Lamb wastage for the mixed age ewes has decreased 0.70±0.08%/yr (R2 = 0.88) to 15% in 2023 and, although more variable (R2 = 0.13), the wastage in two-tooths has also reduced from 32% (2014) to 21% (2023). Lamb wastage is negatively related to two-tooth weight at set-stocking, so feeding young stock is a priority. Since 2016, pre-weaning merino lamb growth rates have averaged 286±4.39 g/hd/d with weaning now at 79.3±2.56 days. This consistency coincided with the addition of 210 ha of feed under pivot irrigation that was initially sown in red and white clover and is now in lucerne/grass mixes. The additional feed has meant wool production has remained constant throughout the 15 years of pasture development. Cow numbers have been used to buffer the changes in pasture supply as the dryland and pivot development occurred. These have now increased to their highest level since the development began. The major change in farm income has resulted from the earlier sale of more lambs at a higher average price because they are heavier due to the extra feed. This unique long-term dataset of on-farm performance provides a commercial example of transformational change that has resulted from changes in the farm system, driven by direct feeding of dryland lucerne and irrigation development focused on growing young stock in this 420 mm rainfall environment.

Genetic parameters for Mycoplasma ovipneumoniae nasal DNA copy number provide progress to promote domestic and bighorn sheep coexistence on public lands

Discord between domestic sheep producers and bighorn sheep conservationists primarily involves concerns over the transmission of Mycoplasma ovipneumoniae between domestic and wild sheep. To discern if selective breeding within the Rambouillet could serve to reduce transmission, a genetic approach utilizing an existing phenotype was evaluated for additive genetic variance. The phenotype employs the measure of nasally shed bacterial DNA, or M. ovipneumoniae nasal DNA copy number (MONCN). Following estimation of the additive genetic variation associated with MONCN, the heritability and repeatability for this trait was calculated. The level of MONCN was measured at least three times per year at the U.S. Sheep Experiment Station (USSES) from ewes ranging from 1 to 7 years of age. Repeated measures animal models were evaluated from 320 ewes with a total of 1223 samples (mean = 3.8 per ewe). The MONCN values ranged from 0 (non-detected) to 71,654 copies per 2 μl of extracted nasal swab DNA. Four genetic models were evaluated with the categorical model having the highest heritability (0.12 ± 0.09) and repeatability (0.60 ± 0.05). Fixed effects included season/year (n = 9) and ewe age (n = 7). Outcomes from this research resulted in heritability estimates from which breeding values can be estimated to select USSES ewes and rams for reduced MONCN. This research provides a practical approach that can be immediately implemented to manage domestic sheep to be more compatible with bighorn sheep on public lands, providing positive welfare benefits for both species.

Peri-parturient ewe mortality in commercial, southern Australian, non-Merino ewe flocks: establishing the frequency and investigating causes.

The level and cause of ewe mortality over the peri-parturient period is poorly understood in Australia. The purpose of this study was to determine the frequency of peri-parturient ewe mortality and investigate the causes of death in commercial, non-Merino ewes over the peri-parturient period. An observational study involving 50 commercial, non-Merino farms across southern Australia during two lambing seasons was conducted. The study population was the breeding flock of ewes on each farm. Ewes were monitored by farmers from the time they were first placed in their lambing paddocks before lambing, up until lamb marking (the lambing period). The project required no change to normal practice. Veterinarians conducted postmortem (PM) examinations at three time points on each farm over the lambing period. A standard PM protocol was followed by all participating veterinarians. The mean peri-parturient mortality over the lambing period was 2.5% in Year 1 and 2.0% in Year 2, with no significant difference between years. Factors that increased the risk of peri-parturient ewe mortality included ewe age (>5 years old) and litter size (triplet-bearing ewes). The most common causes of ewe death according to farmers was dystocia and unknown causes. The three most common diagnoses on veterinary PM examination were dystocia, septicaemia and trauma. This study reveals the relative importance of each cause of ewe mortality over the peri-parturient period. Risk reduction could include identification and management of older ewes (aged above 5 years or older) and ewes carrying twins or triplets.

7395 Developmental Programming: Adverse Effects Of Prenatal Exposure To A Real-Life Environmental Chemical Mixture Via Biosolids On Ovarian Folliculogenesis In Adult Sheep

Abstract Disclosure: Y. Zhou: None. K.M. Halloran: None. M. Bellingham: None. N.P. Evans: None. R.G. Lea: None. K.D. Sinclair: None. V. Padmanabhan: None. The ovarian capacity to provide fertilizable oocytes, regulate folliculogenesis as well as activate and progress primordial follicles into preovulatory follicles are key contributing factors to female fertility and reproductive aging. In sheep, as in humans, while genetics play a role in establishing the ovarian reserve during fetal development, developmental insults such as inappropriate exposure to native steroids or environmental chemicals (ECs) can adversely impact the establishment of the ovarian reserve and, additionally can affect folliculogenesis. Considering humans are exposed to multiple ECs simultaneously which could have additive, synergistic, or antagonistic effects, real-life EC exposure models are needed to assess risks posed by EC exposure. Offspring from sheep grazed on biosolids-treated pasture offers one such real-life exposure model. Studies with day 140 fetuses found maternal exposure to a real-life EC mixture via biosolids increased the proportion of unhealthy transitory follicles (Lea et al., Sci Rep. 2016;6:22279). The present study tested if biosolids exposure during fetal life would impact folliculogenesis, follicle activation and follicle atresia during their adult life. Ovaries were derived from adult EasyCare ewes (age 31.4 ± 0.5 months) whose mothers were grazed on biosolids-treated (BTP, n=10) or inorganic fertilizer-treated (Control, n=10) pastures from preconception through to birth. Ovarian morphometry was undertaken to assess the distribution and health status of follicles. Follicular atresia was evaluated via the expression of Caspase-3, an apoptosis marker. Data analysis utilized Student's t-test for normally distributed variables and Mann-Whitney U tests for non-parametric comparisons. There were no differences in the absolute counts or the percentages of follicle classes at all stages of folliculogenesis, the density of primordial follicles in cortical tissue, or the follicular activation rate. An increase in the percentage of unhealthy activated follicles (post-primordial) was noted in the BTP group (p = 0.014), predominantly in the transitory stage (p = 0.021). Consistent with this, a higher density of Caspase-3 positive primary follicles was observed in the BTP group (p = 0.033). These findings indicate the adverse impacts of fetal exposure to an EC mixture via maternal biosolid exposure on the survival of early-stage activated follicles in adult sheep. The lack of difference in ovarian reserve between the control and BTP groups suggests compensatory mechanisms may be in place to prevent premature depletion of the ovarian reserve. Whether EC mixture exposure via biosolids also has an adverse effect on the quality of the surviving activated follicles remains to be determined. Funding source: NIH R01 ES030374. Presentation: 6/3/2024

Effect of protein polymorphisms on milk composition, coagulation properties, and protein profile in dairy sheep

The objective of this study was to quantify the effect of protein polymorphisms on milk composition, coagulation properties, and protein profile in dairy sheep from a New Zealand flock. A total of 470 test-day records, from 147 lactating ewes, were used in the statistical analyses. Protein polymorphisms observed in the RP-HPLC were self-named for purposes of the present study. Data were analyzed using a mixed linear model, including the fixed effects of ewe age, litter size, coat-colour, and stage of lactation, and, as a covariate, deviation from the median lambing date of the flock. The effects of protein polymorphisms were added to the model, one at a time. Protein polymorphisms were significantly (p < 0.05) associated with milk composition and protein profile. Polymorphisms of β-lactoglobulin were significantly associated with milk heat stability, being AB type more heat stable than AA. The other processability traits were not significantly affected by protein polymorphisms. Further studies are required to confirm the protein variants and the properties of individual protein polymorphisms.

A study on the genetic and phenotypic factors affecting specific ewe productivity traits in Sangsari sheep.

The study's objectives were to assess the genetic parameters of reproductive characteristics in Sangsari sheep. A data set of reproductive information with pedigree details from 1995 to 2016 was used. Studied traits were litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born (LMWLB), litter mean weight per lamb weaned (LMWLW), total litter weight at birth (TLWB) and total litter weight at weaning (TLWW). Test significance of the environmental factors to be included in the model was conducted using the general linear model procedure of the SAS program. All traits were significantly affected by the year of lambing and ewe age at lambing (P < 0.01). The AI-REML procedure of the Wombat program was used to evaluate genetic parameters. A series of bivariate animal models were employed to calculate genetic (rg) and phenotypic (rp) correlations between traits. The total least square means ± standard error of LSB and LSW were 1.04 ± 0.05 and 0.96 ± 0.03, while LMWLB, LMWLW, TLWB, and TLWW were 3.12 ± 0.08, 15.40 ± 0.13, 3.28 ± 0.04, and 19.31 ± 0.16kg, respectively. The estimates of h2 were relatively low (P < 0.01) and ranged from 0.063 ± 0.028 for LSW to 0.181 ± 0.063 for TLWW. Repeatability estimates varied from 0.101 for LSW to 0.241 for TLWW. The sire service effects for LMWLB, TLWB, and TLWW were 0.012 ± 0.004, 0.023 ± 0.006, and 0.039 ± 0.009, respectively. The traits studied showed a greater magnitude of genetic correlation than phenotypic correlation, with values ranging from - 0.59 (LSB-LMWLB) to 0.87 (LMWLB-TLWB). It appears that focusing on TLWW for selection could result in more significant improvements in the reproductive performance of Sangsari ewes.

ВОЗРАСТНАЯ ДИНАМИКА ПРОМЕРОВ ТЕЛА И ИНДЕКСОВ ТЕЛОСЛОЖЕНИЯ МОЛОДНЯКА ОВЕЦ ТУШИНСКОЙ ПОРОДЫ В ЗАВИСИМОСТИ ОТ ВОЗРАСТА РОДИТЕЛЕЙ

Research study of the biological characteristics of rams and ewes of different ages and their ability to transmit to their offspring the qualities required by the breeder which were obtained as a result of crossing is a very important and urgent task. To identify the best age combination of parents used to produce highly productive offspring, it is necessary to study not only the fertility and fertility of the queens of the selected breed as well as the safety of the resulting offspring, but also the exterior characteristics of the resulting offspring. For our research 1200 heads of Tushino breed sheep were selected and 4 groups of different ages were formed. The queens were inseminated with elite rams, of which, in turn, 3 age groups were formed. The characteristic measurements of the offspring obtained as a result of such mating were studied. Based on the experimental data, we can conclude that the little ones received from young and older parents are significantly inferior in all respects to their peers received from middle-aged parents. The same picture is observed in rams. Middle-aged parents gave birth to offspring that are the best in all respects.

Polymorphism in SNP G1 of the GDF9 gene associated with reproductive traits in Bulgarian dairy sheep

The Bulgarian Dairy Synthetic Population (BDSP) is the most numerous sheep breed in the country with a fertility of about 150%. Fertility in sheep is mainly determined by several major genes known as fecundity genes (Fec), one of which is GDF9 (growth differentiating factor 9). The aim of this study was to analyze the association of the GDF9 gene polymorphism at SNP G1 with litter size depending on age and birth type in BDSP ewes. The analysis included 163 sheep in which a 462 bp fragment of exon 1 of the GDF9 gene was amplified and subsequently cut with the restriction enzyme HhaI. As a result, two alleles were established: the wild-type G (with a frequency of 0.76) and the mutant A (with a frequency of 0.24), as well as the three possible genotypes AA, AG and GG with frequencies of 0.06, 0.35 and 0.59, respectively. There was no statistically significant difference in litter size between different genotypes at SNP G1. Significant differences were found in the litter size of the 2nd lambing (1.52) compared to the 4th lambing ewes (1.77), and in the single-born ewes (1.56) compared to ewes born as twins (1.70) (p ≤ 0.05). Proven higher fertility was observed in ewes born as twins with genotype AA (1.97) compared to twins born as carriers of heterozygous genotype AG (1.65) (p ≤ 0.05).

Anti-Müllerian hormone as a promising novel biomarker for litter size in Romanov sheep.

Anti-Müllerian hormone (AMH) is a hormone produced by growing preantral and antral follicles of the ovary. AMH is accepted as an important biomarker for fertility and superovulation parameters in livestock species. This study aimed to evaluate changes in serum AMH level in the oestrous cycle, repeatability of AMH, the effect of age on serum AMH level and the effects of AMH on litter size in Romanov sheep. In the study, a total of 36 Romanov sheep were used as animal material. First blood samples (0th day) were collected from 36 ewes to evaluate AMH and progesterone levels. Second blood samples were collected randomly from 20 ewes 9 days after first sampling to compare AMH levels at two different periods of the oestrous cycle in Romanov ewes. The ewes were categorized into three groups as low, medium and high AMH based on their first AMH levels. Results indicated that serum AMH level did not change during the oestrous and dioestrous phases of the oestrous cycle and two random time points of the oestrous cycle (p > .05). Pearson correlation analysis revealed that there is a high (r = .95) and significant (p < .001) correlation between AMH levels at the 0th (AMH-1) and 9th (AMH-2) days. The effect of AMH level on litter size was found to be significant. Litter size was significantly higher in the high AMH group than in the low AMH group (p < .05). In addition, the age of ewes did not affect serum AMH levels (p > .05). ROC analysis indicates that AMH cut-off value >320 pg/mL with 70% sensitivity and 100% specificity can be used for litter size in Romanov ewes. In conclusion, AMH is highly repeatable and its serum AMH level did not change during the oestrous cycle in Romanov sheep. In addition, AMH affects litter size and can be reliably used as a marker for litter size in Romanov sheep.

An analysis of fertility and fecundity in the Australian sheep flock between 2006 and 2019

After decades of decline, the Australian sheep flock aspires to rebuild its population of breeding ewes. A successful, rebuild will rely on high pregnancy rates and number of lambs born and reared. To examine this potential, a cross-sectional study of historical ultrasound pregnancy scanning records was undertaken using records collated from two experienced sheep pregnancy scanning businesses (years 2006 to 2019) from 15,397 mobs of ewes, totalling 7,443,314 ewes. Client details were de-identified and excluded from analyses, but details describing the mobs were retained when available, such as season of mating, production zone, ewe age, and breed. The key finding was a mean pregnancy rate (ewes pregnant per ewe scanned) of 0.76 ± 0.24, with a median of 0.83. Mobs scanned to identify fetal number had a higher mean (0.84 ± 0.15) and median (0.89) pregnancy rate. The mean reproduction rate (fetuses per ewe scanned) was 1.21 ± 0.27 and the median was 1.25. Differences were observed between the factors including age, breed, season, year or production zone but all results were lower than anticipated. The unexpected findings imply a problem exists with the fertility of many Australian sheep flocks.

Effects of β-carotene supplementation and age on the oxidative status, production and reproductive performance of grazing ewes

Context There is some evidence that physiological stages such as breeding, pregnancy, parturition and lactation may trigger oxidative stress. It has also been observed in several species, including sheep, that age affects their vulnerability to oxidative stress. Aims This study investigated the effects of supplemental β-carotene and age on the oxidative status of grazing ewes around breeding, pregnancy, parturition and early lactation as well as on their production and reproduction performance. Methods Hundred and four ewes were divided into two broad age groups (young = 1–3 years, and old = 4–6 years). Within age groups, ewes of similar age were randomly assigned to four treatment groups (A1, A2, A3, C) by using a completely randomised block design. The young (n = 13) and old (n = 13) sheep in Groups A1, A2 and A3 were daily drenched with 100 mg, 75 mg and 50 mg β-carotene respectively. Group C was unsupplemented (Control). Supplementation lasted 28 days before oestrus synchronisation; 14 days during oestrus synchronisation (CIDR) and hand-mating; 18 days post-hand-mating; 30 days before lambing; and 15 days after lambing. All animals were grazed on Kikuyu grass (Pennisetum clandestinum). Six ewes from each group (total = 24) were sampled for blood to measure oxidative and hormonal status during the experiment. Key results Supplemental β-carotene at ≥75 mg/day may act as a pro-oxidant in ruminants under oxidatively stressed conditions such as parturition. Age did not affect the ewes’ oxidative status. The supplemental β-carotene did not affect bodyweight, oestrus parameters, corpus luteum size, conception rate and litter size. Except for a tendency of lambs from supplemented ewes to have heavier weight at 15 days old (P = 0.080), age group and supplemental β-carotene did not affect the lamb mortality rate or weight at birth or 15 days old. Older ewes showed earlier and longer duration of oestrus than did younger ewes. Conclusions Supplementation of grazing ewes with β-carotene should not be ≥75 mg/day, especially at parturition period, because it may work as a pro-oxidant. The older ewes seem to have earlier oestrus with a longer duration than do the younger ones. Implications Caution is urged when administering high doses of β-carotene to ewes during the peri-parturient period.

Stress response to social isolation followed by exposure to a novel object in aged ewes born to undernourished mothers

Fetal programming by subnutrition affects offspring’s behaviour, metabolism, and sensitivity to stressors in sheep. The objective was to determine the stress response of ewes born to mothers nutritionally restricted during gestation to social isolation followed by exposure to a novel object. Twenty-six-year-old Corriedale ewes born to mothers who grazed high or low pasture allowances (HPA and LPA groups) from 23 days before conception until 122 days of gestation were used. Ewes were individually isolated in a novel place for 10 min, and 5 min after its beginning, an orange ball was dropped into the test pen. The ewes’ behaviours were recorded during the test. Blood proteins, glucose and cortisol concentrations, heart and respiratory rates and rectal and surface temperatures were determined. The number of times looking at the ball tended to be greater in HPA ewes than LPA (6.7 ± 1.0 vs 4.7 ± 0.8, P = 0.08). The LPA ewes had greater serum albumin concentration than HPA ewes (3.2 ± 0.1 g/dL vs 3.0 ± 0.1 g/dL, P = 0.02), regardless of the applied stressors. Overall, the nutritional treatments applied to ewes during their intrauterine development did not modify the stress responses to social isolation followed by exposure to a novel object.

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

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

Exploring Endogenous and Exogenous Factors for Successful Artificial Insemination in Sheep: A Global Overview.

Artificial insemination (AI) plays a vital role in animal breeding programs. AI is applied to enhance animal genetics and facilitate the widespread integration of desirable characteristics with a high potential for productivity. However, in sheep, this biotechnology is not commonly practicable due to multi-factorial challenges, resulting in inconsistent outcomes and unpredictable results. Thoughtful selection of semen donors and recipients based on genetic merit deeply impacts ovine AI outcomes. Additionally, endogenous factors such as breed, age, fertility traits, genetic disorders, and cervical anatomy in ewes contribute to ovine AI success. Extensive research has studied exogenous influences on sexual behavior, reproductive health, and hormonal regulation, all impacting ovine AI success. These exogenous factors include techniques like estrus induction, synchronization, semen handling methods (fresh/chilled/frozen), and insemination methods (cervical/laparoscopic), as well as nutritional factors and climatic conditions. This overview of the literature highlights the endogenous and exogenous challenges facing successful ovine AI and proposes strategies and best practices for improvement. This paper will serve as a guide for understanding and optimizing the success of ovine AI.

Ovine Brucellosis in Bangladesh: Seroprevalence and its associated risk factors

Aim: Brucellosis is a highly zoonotic and infectious disease caused by different species of the Brucella genus around the world. This disease has a substantial impact on animal and human health, and also on socioeconomic aspects, therefore it could pose a serious impediment to the development of livestock production. There has been a lack of extensive research on the seroprevalence of brucellosis in sheep, as well as risk factor analysis in Bangladesh. As a result, the current investigation was undertaken to estimate the seroprevalence and associated risk factors for ovine brucellosis in Bangladesh. Methods: A total 394 blood samples were randomly collected from eight districts of Bangladesh between July 2021 and June 2022. These samples were examined using both the Rose Bengal Plate Test (RBPT) and the indirect enzyme-linked immunosorbent assay (iELISA) to detect Brucella antibodies. To understand the potential risk factors, a structured questionnaire was used to gather information about sheep rearing from sheep owners through direct interview. Data analysis was done using STATA version 18.0, and logistic regression models were employed to identify relevant risk factors. Results: The study revealed an overall seroprevalence of ovine brucellosis was 5.84% (95% CI: 6.34, 14.25) and 3.55% (95% CI: 6.50, 6.97) using RBPT and iELISA, respectively. Age (over 3 years; OR: 6.56, 95% CI: 1.73–31.48) and parity of ewes (&gt; 3 times; OR: 13.11, 95% CI: 2.82–60.92) were found to be significant risk factors for Brucella seropositivity (p &lt; 0.05). Conclusion: In conclusion, the prevalence of ovine brucellosis in the study area was quite low. Efficient measures are required to be implemented in order to control the transmission of the disease.

Relationship between FAMACHA© scores and zootechnical indicators of a sheep production system

In Brazil, lamb producers face challenges raising their animals because of high anthelmintic resistance and loss of productivity due to parasites. It is well known that parasitic infections can reduce the performance of sheep. However, until the publication of this work, no research was found that quantified the effects that anemia reflected by FAMACHA© scores can exert on other zootechnical indicators in a lamb production system. The objective of this study was to use the FAMACHA© scores to quantify the impacts of anemia in ewes at breeding and lambing on the productive and reproductive performance of a meat sheep flock. The variables evaluated were i) FAMACHA© score of ewes at breeding and lambing, ii) body condition score of ewes at breeding and at lambing, iii) average daily gain of lambs until weaning, iv) ewe’s age, v) birth weights per individual lamb and litter, vi) weaning weight, vii) ewe’s weight, viii) litter size and ix) pre-weaning survival. The treatments evaluated corresponded to the FAMACHA© score of the ewes during breeding and lambing. Quantitative responses were submitted to analyses of variance and compared by Duncan’s test. In contrast, qualitative or discrete responses were evaluated by the Kruskal &amp; Wallis test and compared to Dunn’s test. The Wilcoxon test was performed to compare the FAMACHA© scores of ewes at breeding and lambing. All statistical analyzes were performed using the R-Studio software version 4.2.0 at a 5% significance level. The FAMACHA© score of breeding ewes was related to the body condition score at breeding, ewe weight, pre-weaning survival, ewe age, litter size, and birth weight. Furthermore, the FAMACHA© score of ewes at lambing was related to the body condition score at lambing, ewe weight, pre-weaning survival, birth weight per lamb and litter, pre-weaning average daily gain, weaning weight, and age of the ewe. There was no significant difference between the test times of the FAMACHA© scores of the ewes, indicating that an ewe will present a similar score at both stages. It was concluded that ewes with FAMACHA© scores of 4 and 5 and their offspring showed the worst productive and reproductive performances. Conversely, the ewes with FAMACHA© 1 obtained the opposite result, demonstrating better technical performance.

Mathematical models to predict the lamb weight at birth and at weaning reared in the tropical warm-climate pasture.

Our objective was to evaluate the productive parameters of ewes and their lambs in relation to ewe age and to develop models for predicting lamb weight at birth and weaning in a tropical warm-climate pasture. Individual data were collected from 273 ewes and 273 lambs, between 2013 and 2021. During this period all animals were kept on pastures of Brachiaria brizantha cv. Marandu All lambs in the experiments were supplemented in creep-feeding. A descriptive statistical analysis was performed using the PROC SUMMARY procedure in SAS (SAS University Edition, SAS Institute Inc. Cary, CA, USA). Pearson correlation coefficients between variables were estimated using the PROC CORR procedure in SAS (SAS University Edition, SAS Institute Inc. Cary, CA, USA). Model adjustments and variable selection were performed using PROC REG in SAS (SAS University Edition, SAS Institute Inc. Cary, CA, USA). The STEPWISE option and Mallow's C(p) were used to select the variables included in the equations. Outliers were identified by evaluating the studentized residuals based on the predicted values from the equations. Residual analysis was predicted by regression minus observed values and those that fell outside the range of -2.5 to 2.5 were removed. Several statistics were used to assess the predictability of the equations, including the coefficients of determination (r2) and mean standard error (RMSE). The average ewe age at lambing was 3.4 ± 1.7years, with an average weight of 56.9 ± 8,9kg and average body condition score (BCS) of 2,4 ± 0.8 points. The average ewe age at weaning was 51.1 ± 7.9, with average BCS of 1.8 ± 0.8 points. The average lamb at birthing was 3.9 ± 0.9kg. The average lamb at weaning was 21.0 ± 4.9, with daily gain of 0.2 ± 0.1kg/day and total gain of 17.1 ± 4.7kg birth to weaning. The lamb produced by ewe at lambing was 5.3 ± 1.7kg/ewe. The lamb weaned by ewe at weaning was 28.7 ± 10.8kg/ewe. The ratios of lamb produced per ewe at birth and at weaning were 0.1 ± 0.03 and 0.6 ± 0.2, respectively. The lamb's birth weight showed a positive linear relationship with the age of the ewe, increasing by 115g per year of age. The regression equations adjusted for ewe age had maximum points ranging from 4.2 to 5.2, occurring at average age of 4,7years. The other characteristics showed a quadratic tendency. The results suggest the culling of ewes at five years of age to generate lambs with ideal weight at birth and at weaning raised in warm tropical pastures.