Ewe Flock Research Articles

Neospora caninum is not an important contributor to poor reproductive performance of primiparous ewes from southern Australia: evidence from a cross-sectional study.

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 1-2years 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 3years 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.

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.

Comparison of Pregnancy Rates after Short - Term and Long -Term Synchronization Protocol in Ewes- Pilot Study

The objective of the study was to compare the pregnancy rates after short-term and long-term synchroniza-tion protocol in Kivircik ewes. Ewes (n=54) were randomly divided into two synchronization groups as ST (short-term; n=27) or LT (long-term, n=27). Intravaginal sponge was inserted on the same day (D0) in both groups. It was removed at 7 days (D7) in the ST group and 13 days (D13) in the LT group. All ewes received 450 IU eCG and 75 μg d-cloprostenol at the time of sponge removal. The characteristics of vaginal discharge were evaluated following sponge withdrawal. For both protocols, 5 fertile rams per 27 ewes were used for natural mating following sponge removal. The overall estrous response and pregnancy rate were 88.9% and 64.8%, respectively. Following the synchronization, the overall estrous response (94.7% vs. 85.7%, respectively) and pregnancy rate (63.1% vs. 65.7%, respectively) were similar in both multiparous and nulliparous ewes. Although the short-term protocol reduced the rate of severe vaginitis from 48.1% to 25.9%, pregnancy rates were not different in both synchronization protocols. Nulliparous ewes had a higher rate (48.6% vs. 15.8%) of severe vaginal discharge than multiparous ewes. However, the alteration of the vagi-nal discharge severity depending on parity did not affect the overall pregnancy rate after the short-term (66.7%) and long-term (63.0%) protocols. Therefore, the long-term and short-term protocol can be used in both nulliparous and multiparous ewes in small flocks.

Chlamydia pecorum detection in aborted and stillborn lambs from Western Australia

Lamb survival is an important welfare and productivity issue for sheep industries worldwide. Lower lamb survival has been reported for primiparous ewes, but the causes of this are not well studied. The aim of this study was to determine causes of perinatal deaths for lambs born to primiparous ewes in Western Australia, and identify if infectious diseases are implicated. Lamb mortality from birth to marking were determined for 11 primiparous ewe flocks on 10 farms in Western Australia. Lamb mortality from birth to marking averaged 14% for single-born and 26% for multiple-born lambs. Lamb necropsies (n = 298) identified starvation–mismosthering–exposure (34%), dystocia (24%) and stillbirth (15%) as the most common causes of perinatal lamb death. There was no evidence of exotic abortigenic pathogens in aborted and stillborn lambs (n = 35). Chlamydia pecorum was detected by qPCR in 15/35 aborted and stillborn lambs on 5/6 farms. Preliminary molecular characterisation of C. pecorum detected in samples from aborted and stillborn lambs (n = 8) using both Multilocus Sequence Typing and ompA genotyping indicated all strains were genetically identical to previously described pathogenic livestock strains, denoted ST23, and dissimilar to gastrointestinal strains. High frequency of detection of a pathogenic C. pecorum strains ST23 associated with ovine abortion and stillbirth on multiple farms located across a wide geographic area has not been previously reported. Chlamydia pecorum may contribute to reproductive wastage for primiparous sheep in Western Australia. Further investigation to understand C. pecorum epidemiology and impact on sheep reproduction is warranted.

Coagulase-negative staphylococci in ewe udder surface and raw milk samples

Coagulase-negative staphylococci (CNS) are among the major causes of subclinical mastitis in dairy ewe flocks. This has a financially significant impact on the ewe dairy sector and consumer health. The determination of the bacterial count, particularly CNS, is critical in terms of the quantity and quality of ovine milk. Thus, the purpose of this study was to quantify the CNS count in the udder surface and raw milk samples of the ewe, in addition to identifying CNS strains (n=8) collected from udder surface and individual raw milk samples by 16S rRNA gene sequencing. A total of 164 samples of udder surface and raw milk originated from four sheep farms were tested. The obtained values were compared between the different farms. Furthermore, values during 2018 and 2019 in the case of Farm I were compared. Significantly higher (p&lt;0.05) average count was observed in udder surface samples taken from Farm I (2.8±1.0 lg CFU/cm2) than that of Farm III samples (2.3±0.6 lg CFU/cm2). In the case of individual raw milk, the higher value was observed in samples derived from Farm III (3.5±0.9 lg CFU/mL), while the obtained value was significantly lower (p&lt;0.05) in samples originated from Farm IV (1.8±0.4 lg CFU/mL). In the bulk tank milk samples, the highest mean value was 5.3±0.4 CFU/mL, and there was no significant (p&gt;0.05) variation between farms. Coagulase-negative staphylococci counts were decreased to a certain extent in both sample types tested during 2019 except for individual raw milk derived from the Tsigai breed. The correlation between the mean CNS counts of udder surface and individual raw milk was very weak (r=0.048). Staphylococcus simulans, Staphylococcus auricularis, and Staphylococcus equorum were identified by molecular sequencing and Staphylococcus simulans were the most frequently identified CNS species. A higher CNS count of bulk tank milk than individual raw milk indicates possible contamination during milking and storage. Therefore, further studies are required to investigate the other sources of bulk tank milk contamination to improve the hygienic quality of milk.

Growth Performance of Short Scrotum and Castrated Hair Sheep Lambs on Pasture During Different Seasons

Abstract Castrated lambs tend to grow slower compared to intact males. Rendering lambs short scrotum offers an opportunity to achieve comparable growth to an intact lamb while allowing them to be co-grazed with ewe lambs. Here we evaluated lamb growth in a mixed flock of castrated (CA), short-scrotum (SS) and female (FE) Barbados Blackbelly and St. Croix hair sheep lambs. Lambs were born in December (n = 30) and April (n = 45) from the same ewe flock mated to different sires each season. Ram lambs were either rendered short scrotum or completely castrated using elastrator bands at weaning, and all lambs transitioned in dry lot for 2 mo before return to pasture. Lambs co-grazed in a rotational pasture system and were moved based on visual assessment of forage availability and were provided bermudagrass hay when forage availability was limited. Lambs were supplemented with soy hull at 3% BW to ensure diet continuity between forage environments. Ewe lambs were grown to target weights of 35 kg and males to 40 kg. Data were analyzed for sex class, breed, and season as main effects. Pasture ADG was higher (P &amp;lt; 0.001) in SS (132 g/d) than in CA (102 g/d) and FE (96 g/d) lambs. Age at target weight tended to be earlier (P &amp;lt; 0.1) in SS (261 d) than CA (291 d). December-born lambs had higher pen ADG (236 vs. 135 g/d; P&amp;lt; 0.001) than April-born lambs, but had similar pasture ADG (102 vs. 108 g/d). In contrast, St. Croix lambs had similar pre-pasture growth to Blackbelly lambs, but higher pasture ADG (118 vs. 94 g/d; P &amp;lt; 0.001) and reached target weight 40 d earlier (P &amp;lt; 0.001). Data indicate that the forage environment allowed differences in growth potential derived from sex type and breed to be expressed, but that soy hull supplementation likely masked seasonal differences associated with forage quality.

Determining the Impact of Hogget Breeding Performance on Profitability under a Fixed Feed Supply Scenario in New Zealand.

Hoggets (ewe lambs aged 4 to 16 months) can be bred from approximately 8 months of age for potentially increased flock production and profit, however most New Zealand hoggets are not presented for breeding and their reproductive success is highly variable. Bio-economic modelling was used to analyse flock productivity and profit in four sets of scenarios for ewe flocks with varying mature ewe (FWR) and hogget (HWR) weaning rate combinations. Firstly, hogget breeding was identified to become profitable when break-even HWRs of 26% and 28% were achieved for flocks with FWRs of 135% and 150%, respectively. Secondly, relatively smaller improvements in FWR were identified to increase profit to the same level as larger improvements in HWR. Thirdly, a high performing flock with FWR and HWR both ≥ the 90th percentile currently achieved commercially, was the most profitable flock modelled. Fourthly, a FWR was identified with which a farmer not wishing to breed hoggets could have the same profit as a farmer with a flock achieving current industry average FWR and HWR. Overall, the relative profit levels achieved by the modelled flocks suggest that more farmers should consider breeding their hoggets, though improvements in FWRs should be prioritised.

Advances in managing pregnancy toxaemia in sheep

Background: Ovine pregnancy toxaemia (OPT) is a metabolic disorder of ewes in late pregnancy. Cases are typically seen in ewes carrying multiple fetuses, hence the alternative name of ‘twin lamb disease’. The disease has been well known for many years. Despite this, the toll inflicted by the disease remains considerable, due both to the poor prognosis of clinically affected animals, even with appropriate treatment, and the impact of the provoking factors of under‐nutrition and concomitant disease on ewe morbidity, lamb survival and flock productivity. Cases of OPT are an indication of shortcomings in the management of late‐pregnancy ewes.Aim of the article: This article provides an update on the aetiopathogenesis, diagnosis, treatment and prevention of OPT, drawing on recently published studies.

Sheep mastitis caused by staphylococci and streptococci and their influence on oxidative status

Article Details: Received: 2020-10-14 | Accepted: 2020-11-27 | Available online: 2021-01-31 https://doi.org/10.15414/afz.2021.24.mi-prap.53-57 Abstract The objectives of this study were to determine the relationship of oxidative product levels, using malondialdehyde (MDA) as a marker on occurrence of mastitis and its causing pathogens in two dairy flocks of ewes situated in east and north of Slovakia. The diagnosis of mastitis was performed on the basis of clinical examination of the udder, macroscopic evaluation of milk, with the evaluation of Californian mastitis test (CMT) and bacteriological analysis of individual raw milk samples. From total 537 and 444 halves ewe’s milk samples were 16.6% and 23.2% positive to CMT, respectively. The prevalence of mastitis caused by bacterial pathogenes in the monitored herds was 14.3% to 19.1%, respectively. In all monitored sheep flocks were confirmed predominantly subclinical forms (SM) of intramammary infection (IMI). The highest of etiological agents in all monitored herds had coagulase negative staphylococci and coagulase positive staphylococci especially Staphylococcus aureus . Except for staphylococci were Streptococcus uberis and Streptococcus spp. most frequently pathogens isolated from mastitic sheep. The highest MDA level was observed from clinical cases of mastitis however, increased MDA levels were detectable from subclinical cases. Bacterial isolates from mastitc halves milk samples are different in levels of MDA. In this study, we found that milk samples infected with S. aureus were higher compared to other pathogens. In conclusion, differences in both severities of IMI and mastitis pathogens were associated with differences of MDA in infected udders. Keywords: sheep, milking, mastitis, lipid peroxidation, S. aureus , coagulase negative staphylococci References Contreras, A. et al. (2007). Mastitis in small ruminants. Small Ruminant Research, 68(1-2), 145–153. https://doi.org/10.1016/j.smallrumres.2006.09.011 Fthenakis, G. C. (1995). California mastitis test and White side test in diagnosis of subclinical mastitis of dairy ewes. Small Ruminant Research , 16(3), 271–276. https://doi.org/10.1016/0921-4488(95)00638-2 Hariharan, H. et al. (2004). Bacteriology and somatic cell counts in milk samples from ewes on a Scottish farm. Canadian Journal of Veterinary Research, 68(3), 188–192. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1142138/ Malinowski, E. et al. (2008). Etiological agents of dairy cows’ mastitis in western part of Poland. Polish Journal of Veterinary Sciences, 9(3), 191-194. https://pubmed.ncbi.nlm.nih.gov/17020014/ Mork, T. et al. (2007). Clinical mastitis in ewes; bacteriology, epidemiology and clinical features. Acta Veterinaria Scandinavica , 49(1), 23. https://dx.doi.org/10.1186%2F1751-0147-49-23 Pyorala, S. and Taponen, S. (2009). Coagulase-negative staphylococci - Emerging mastitis pathogens. Veterinary Microbiology , 34(2), 3–8. https://doi.org/10.1016/j.vetmic.2008.09.015 Sharma, N. (2011). Oxidative stress and antioxidant status during transition period in dairy cows. Asian-Australian Journal of Animal Science , 24(4), 479–484. https://www.ajas.info/upload/pdf/24-58.pdf Suriyasathaporn, W. (2006). Higher somatic cell counts resulted in higher malondialdehyde concentrations in raw cow´s milk. International Dairy Journal, 16(9), 1088–1091. https://doi.org/10.1016/j.idairyj.2005.11.004 Turk, R. et al. (2017). The role of oxidative stress and inflammatory response in the pathogenesis of mastitis in dairy cows. Mljekarstvo, 67(2), 91–101. https://doi.org/10.15567/mljekarstvo.2017.0201

Proximity sensors provide an accurate alternative for measuring maternal pedigree of lambs in Australian sheep flocks under commercial conditions

Context Proximity sensors were used recently to determine the maternal pedigree of lambs on a small plot with high accuracy. If this accuracy is maintained under commercial grazing conditions, this method could be a useful alternative to improving genetic gain in sheep, including reproduction traits. Aims To investigate using proximity sensors to determine the maternal pedigree of lambs and to define the level of interactions required to determine maternal pedigree confidently irrespective of differences in ewe age, lamb age, birth type, paddock size, flock size or stocking rate under commercial grazing conditions. Methods We compared maternal pedigree determined using the proximity sensors to DNA profiling (n = 10 flocks) and lambing rounds (n = 16 flocks). Ewes (n = 7315) and lambs (n = 8058) were fitted with proximity sensors under normal grazing conditions for each property for 1–3 days. Flocks varied in ewe age (adults, hoggets and ewe lambs), lamb age (up to 100 days old, except for 1 flock), birth type (singles, multiples), paddock size (0.25–320 ha), flock size (37–420 lambs) and stocking rate (2–100 dry sheep equivalents/ha, except for 1 flock). Key results An interaction ratio of &gt;2 was required for a confident ewe–lamb match (ewe with the most interactions compared with the ewe with the second-most interactions for each lamb). Using this criterion, the average success of proximity sensors at matching a lamb to a ewe was 95% and the sensors were 97% accurate when compared with the pedigree results from lambing rounds or DNA. For lambs matched successfully, over 90% of this success was achieved in the first 7 h and over 99% in the first 20 h. While the success rate of matching a lamb to a ewe was not influenced significantly by ewe age, birth type, paddock size, flock size or stocking rate, the time to achieve sensor success was significantly quicker for singles than for twins and sensor accuracy was significantly higher for smaller paddocks with higher stocking rates. Conclusions Our results showed that proximity sensors can establish maternal pedigree effectively and accurately across a range of conditions experienced on commercial properties. Implications Private industry can now develop more cost-effective sensor technologies with greater confidence that will enhance recording of maternal pedigree and, hence, the rate of genetic gain across the sheep industry.

Effect of level of infection by gastrointestinal nematodes and anthelmintic treatment on milk yield in dairy sheep

The effects of gastrointestinal nematode infections and anthelmintic treatment on milk yields was compared between flocks with a low level (LL) of eggs per gram (epg) before partum and with a high level (HL). Faecal egg count reduction tests (FECRTs) were carried out before partum comparing a treated group with netobimin with an untreated group. Ewes belonging to LL flocks produced 55.4% more milk than ewes from HL flocks. A negative correlation was found between the mean epg before treatment and the mean milk yield per flock (r = −0.860; p < 0.01). However, treated ewes produced 10.1% more milk than untreated ewes in LL flocks, although in HL flocks, treated ewes produced less milk (−2.7%). The treatment of flocks even with low levels of infection can improve the milk yields. In this study, the epg before partum had a greater influence on total milk yield than the anthelmintic treatment.

142 Reproductive performance of land race hair sheep ewes in different breeding seasons under a semi-continuous production

Abstract A system for semi-continuous lamb production was evaluated using Barbados Blackbelly and St. Croix hair sheep ewes under 8-mo accelerated mating. Ewes were managed in a forage-based production system using rotational grazing. Two flocks of ewes (n = 30–35), equally representing the breeds, were bred 4 mo apart. Ewes were synchronized by feeding melengestrol acetate for 10 d, and mated in two single sire groups to like breed sires in November (NOV), March (MAR), and July (JUL) in a 25-d mating period. Pregnancy was recorded by transrectal ultrasound 22 d after breeding. Ewes were supplemented with corn/soybean meal during late gestation (0.75% of BW) and during lactation (1.5% of BW). They lambed on pasture with limited supervision, and lambs were weaned at 2 mo of age. Lambs had access to the supplement provided to ewes. Ewe performance (pregnancy rate, litter size, lamb survival, and birth and weaning weight) was recorded during a 2 yr production cycle, and analyzed for the effect of mating season. Pregnancy rate was not statistically different (P &amp;gt; 0.1) between season, and ranged from 93.9% in NOV, to 85.9 and 86.6% in MAR and JUL. Litter size (lambs born/ewe lambing) was higher (P &amp;lt; 0.05) in NOV (2.09) than MAR (1.68) and JUL (1.82). Lamb survival at birth was reduced (P &amp;lt; 0.001) in JUL (86.5%) compared to NOV (99%) and MAR (100 %), but was not different between seasons for survival to weaning (86 to 90%). Lamb birth weights were higher (P &amp;lt; 0.05) in MAR (3.16 kg) than JUL (2.99 kg), with NOV (3.05 kg) intermediate, while lamb weaning weights were higher (P &amp;lt; 0.001) in NOV (13.6 kg) compared with MAR (11.9 kg) and JUL (11.4 kg) mating. Data suggest that dual flock, accelerated mating of landrace hair sheep ewes can produce lamb cohorts of similar size in 4 mo intervals under a low-input, forage-based production system.

The Impact of Hogget and Mature Flock Reproductive Success on Sheep Farm Productivity

Breeding hoggets (ewe lambs aged four to 16 months) at 8 to 9 months of age has a number of potential benefits, including increased lamb production and profitability. However, the majority of hoggets in New Zealand are not bred due to producer concerns regarding their variable reproductive success and increased feed demand. Simulation modelling was used to quantify effects of hogget breeding on sheep numbers, lamb production, sheep feed demand, and sheep enterprise cash operating surplus (COS) compared with a flock not breeding hoggets. Hogget weaning rate (HWR) was modelled at 0%, 60%, 80%, and 100% and combined with mature ewe flock weaning rates (FWR) of 132% and 150%, while maintaining total annual sheep feed demand. For each FWR, increased HWR reduced total sheep numbers, increased the proportion of sheep feed demand for lamb production, increased total numbers of lambs weaned, and increased COS. Therefore, achieving even a relatively low HWR of 60% can improve sheep enterprise profitability for a given FWR. However, COS was lower with FWR = 132% and HWR = 100% than with FWR = 150% and HWR = 0%. The results indicate farmers who do not currently breed their hoggets may wish to improve their FWR before considering HWRs.

The 1B vaccine strain of Chlamydia abortus produces placental pathology indistinguishable from a wild type infection.

Chlamydia abortus is one of the most commonly diagnosed causes of infectious abortion in small ruminants worldwide. Control of the disease (Enzootic Abortion of Ewes or EAE) is achieved using the commercial live, attenuated C. abortus 1B vaccine strain, which can be distinguished from virulent wild-type (wt) strains by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Published studies applying this typing method and whole-genome sequence analyses to cases of EAE in vaccinated and non-vaccinated animals have provided strong evidence that the 1B strain is not attenuated and can infect the placenta causing disease in some ewes. Therefore, the objective of this study was to characterise the lesions found in the placentas of ewes vaccinated with the 1B strain and to compare these to those resulting from a wt infection. A C. abortus-free flock of multiparous adult ewes was vaccinated twice, over three breeding seasons, each before mating, with the commercial C. abortus 1B vaccine strain (Cevac® Chlamydia, Ceva Animal Health Ltd.). In the second lambing season following vaccination, placentas (n = 117) were collected at parturition and analysed by C. abortus-specific real-time quantitative PCR (qPCR). Two placentas, from a single ewe, which gave birth to live twin lambs, were found to be positive by qPCR and viable organisms were recovered and identified as vaccine type (vt) by PCR-RFLP, with no evidence of any wt strain being present. All cotyledons from the vt-infected placentas were analysed by histopathology and immunohistochemistry and compared to those from wt-infected placentas. Both vt-infected placentas showed lesions typical of those found in a wt infection in terms of their severity, distribution, and associated intensity of antigen labelling. These results conclusively demonstrate that the 1B strain can infect the placenta, producing typical EAE placental lesions that are indistinguishable from those found in wt infected animals.

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.

Potential profit gains from improving pasture productivity on New Zealand South Island high-country farms

Soil acidity combined with low levels of key nutrients on New Zealand hill-country farms are limiting factors for legume establishment/growth. However, legumes are a critical component of these farms as they provide nitrogen and high-quality feed. A farm-systems model was developed to estimate the impact of targeted fertiliser and lime application, combined with sowing clover, on whole-farm productivity and profitability. A base model was developed that incorporated 17 years’ worth of Beef + Lamb NZ survey data for Class 1: South Island Farms. This base model was then used investigate two lime-application/oversowing models where part of the modelled high-country farm was targeted for improvement: (1) Conservative, i.e. 0.6% farm area; and (2) Aggressive, i.e. 2.8% farm area. Three scenarios to utilise the additional pasture grown were then investigated for each model by: (a) increasing ewe numbers; (b) increasing ewe performance (lambing percentage); and (c) increasing liveweight gain of stock. Scenario 2a, generated the highest profitability level (Earnings before Interest Tax and Rent, EBITR $58,870) above the base model but became less financially attractive when the two years required to build the maternal ewe flock were factored in. Scenarios 2c and 1b generated increases in profitability (EBITR) between $33,310 and $41,290 above the base model. Variation in product prices, production levels and time to develop the final farm-management system would also influence the productivity and profitability of the scenarios. Environmental aspects, infrastructure and staff availability would affect the suitability of the development for individual farming businesses.

Correlations between feed intake, residual feed intake and methane emissions in Maternal Composite ewes at post weaning, hogget and adult ages

Sheep production in southern Australia (particularly south west Victoria) is based increasingly on the Maternal Composite ewe, a self-replacing stable crossbred. Breeding programs have focussed on maternal traits such as reproduction and lamb growth. Understanding the variability, range and correlations between the traits of residual feed intake (RFI), feed intake (dry matter intake, DMI), growth rate and methane (CH4) emissions within the Maternal Composite ewe flock is essential to development of selection parameters that improve feed efficiency and reduce environmental impact. Sheep and cattle with low RFI (more efficient) have been observed to produce less CH4 than animals with high RFI. Selecting for animals with improved RFI may enable producers to improve the enterprise productivity while decreasing greenhouse gas emissions.

Producing higher value wool through a transition from Romney to Merino crossbred ii: Cashflow and profit

• Bio-economic system-dynamics modelling of a Romney flock bred with Merino sires for whole flock breed transition. • Profit decreased during transition, but was greater post-transition than for Romney flock. • Economic benefit of transition ranged from zero to an increase of up to 26 %. • Greatest economic benefit with higher lamb selection intensity and longer transition. • With higher selection intensity, post-transition wool had lower fibre diameter and higher value. Data suggests crossbreeding a Romney ewe flock with Merino sires to achieve a second cross ¾ Merino ¼ Romney (¾M¼R) flock would reduce wool fibre diameter and increase income from wool sales. It is not known how cashflow would vary during such a breed transition and which factors would affect the profitability of such a strategy. A bio-economic system-dynamics modelling study was conducted to simulate the breed transition with low or high selection intensity (24 % vs. 35 % of crossbred ewe lambs not retained at each of two selection events) and either consistent lambing rate (132 % for all flocks) or breed specific lambing rate (lower for Merino-Romney crossbred flocks). Although sheep enterprise profit was always greater post-transition compared with the base Romney flock, during transition annual profit was reduced below that of the base Romney flock. The total cashflow of the breed transition (i.e. twelve years) ranged from relatively small or no economic benefit, to up to 26 % greater than maintenance of the base Romney flock. The most profitable breed transition strategies modelled had higher Merino-Romney ewe lamb selection intensity, achieved greater wool fibre diameter reductions, and occurred over a longer breed transition period.

Producing higher value wool through a transition from Romney to Merino crossbred i: Flock dynamics, feed demand, and production of lambs and wool

Abstract Data suggests crossbreeding a Romney ewe flock with Merino sires to achieve a second-cross ¾ Merino ¼ Romney (¾M¼R) flock could reduce wool fibre diameter to take advantage of increasing medium wool (fibre diameter > 24 μm and

Quantifying sheep enterprise profitability with varying flock replacement rates, lambing rates, and breeding strategies in New Zealand

Sheep sales are the major source of income for most New Zealand sheep enterprises. Terminal (meat breed) sires are used to increase lamb growth rates enabling lambs to be sold earlier at higher prices on a per kg basis. Their use in self-replacing flocks is generally constrained by requirements for purebred ewe lambs from which to choose ewe replacements. This study used a bio-economic system-dynamics model of a sheep enterprise to investigate use of terminal sires for a ewe flock with a range of ewe replacement and lambing rates. Values from New Zealand industry survey data were used to simulate a representative New Zealand North Island East Coast Hill Country sheep enterprise (self-replacing flock of 2182 mature breeding ewes with a stable flock size on 549 ha of pasture where 60.8% of feed was consumed by sheep). Three ewe replacement rates (20%, 25%, and 30% per annum), lambing rates (110, 130, and 150%; lambs weaned per ewe presented for breeding), and breeding strategies (no terminal sires; breeding the maximum possible proportion of mature ewes with terminal sires; and breeding half of the maximum with terminal sires) were modelled. Income from lamb sales increased with use of terminal sires, due to increased production of lamb liveweight for sale and lambs sold earlier for higher prices, resulting in greater sheep enterprise cash operating surplus (COS). Sheep enterprise COS increases, from no terminal sire use compared with maximum use of terminal sires, ranged from $3/ha to $101/ha. Larger increases in COS occurred with a higher flock lambing rate and lower ewe replacement rate, which allowed for terminal sire use over a greater proportion of the flock. Up to 65% of the flock could be bred with terminal sires while producing sufficient numbers of purebred ewe lambs from which to choose replacements. For an average North Island East Coast Hill Country sheep enterprise with a replacement rate of 25% and lambing rate of 130%, sheep enterprise COS increased by $15,021 with maximum use of terminal sires (45% of the mature ewe flock), compared with use of only maternal sires. Use of terminal sires increased annual sheep energy demand by up to 6% and changed the sheep feed demand profile, with increases in energy demand post-weaning in December mostly compensated for by subsequent reductions in demand following crossbred lamb sales in January.