Eating Time as a Genetic Indicator of Methane Emissions and Feed Efficiency in Australian Maternal Composite Sheep

Previous studies have shown reduced enteric methane emissions (ME) and residual feed intake (RFI) through the application of genomic selection in ruminants. The objective of this study was to evaluate feeding behaviour traits as genetic indicators for ME and RFI in Australian Maternal Composite ewes using data from an automated feed intake facility. The feeding behaviour traits evaluated were the amount of time spent eating per day (eating time; ETD; min/day) and per visit (eating time per event; ETE; min/event), daily number of events (DNE), event feed intake (EFI; g/event) and eating rate (ER; g/min). Genotypes and phenotypes of 445 ewes at three different ages (post-weaning, hogget, and adult) were used to estimate the heritability of ME, RFI, and the feeding behaviour traits using univariate genomic best linear unbiased prediction models. Multivariate models were used to estimate the correlations between these traits and within each trait at different ages. The response to selection was evaluated for ME and RFI with direct selection models and indirect models with ETE as an indicator trait, as this behaviour trait was a promising indicator based on heritability and genetic correlations. Heritabilities were between 0.12 and 0.18 for ME and RFI, and between 0.29 and 0.47 for the eating behaviour traits. In our data, selecting for more efficient animals (low RFI) would lead to higher methane emissions per day and per kg of dry matter intake. Selecting for more ETE also improves feed efficiency but results in more methane per day and per kg dry matter intake. Based on our results, ETE could be evaluated as an indicator trait for ME and RFI under an index approach that allows simultaneous selection for improvement in emissions and feed efficiency. Selecting for ETE may have a tremendous impact on the industry, as it may be easier and cheaper to obtain than feed intake and ME data. As the data were collected using individual feeding units, the findings on this research should be validated under grazing conditions.

Automated feeding of sheep. 2. Feeding behaviour influences the methane emissions of sheep offered restricted diets

Context During the non-growing season of pastures and during droughts, the dry-matter intake (DMI) of sheep is often constrained due to low pasture availability and the need to feed for weight loss or maintenance. Below-maintenance feeding may have consequences for methane (CH4) production and yield in farm systems. Aims The effect of six restricted feeding levels on CH4 emissions measured using portable accumulation chambers (PACs) was examined in relation to DMI, oxygen consumption (O2) and carbon dioxide (CO2) emissions and observed changes in feeding behaviour in sheep fed with automated feeders. Methods An automated feeding system was used to apply daily feeding levels to Maternal Composite ewes (n=126). Sheep were adapted to the automated feeding system over 19days, with unlimited access to feed. Following adaptation, sheep were allocated to restricted daily feed levels at 40%, 80%, 100%, 140% and 180% of estimated maintenance requirements (MR) for 41days. Methane, CO2 and O2 emissions from ewes were measured using PACs on Days 30 and 31 of the restricted feeding period. Key results Methane production (g/day) increased (P<0.001) with the level of feeding. However, time since the last meal decreased with the level of feeding and was associated with CH4 production. Sheep on lower levels of feeding tended to consume meals earlier in the day and had longer times since their last meal at PAC measurement and lower CH4 production. These two factors explained 58.7% of the variance in CH4 production in an additive linear model. Methane yield (gCH4/kg DMI) decreased as the level of feeding was increased. Conclusions Methane emissions were affected not only by daily DMI, but also time since the last meal. An understanding of the effect of feeding behaviour and time since the last meal should be incorporated into feeding protocols prior to CH4 measurements when PACs are being used to measure CH4 emissions from sheep fed restricted diets. Implications Utilising automated feeders may improve the accuracy of PAC measurements of sheep CH4 emissions fed both ad libitum and restricted feed amounts, by increasing understanding of DMI and feeding behaviour.

The impact of lamb and ewe mortality associated with dystocia on Australian and New Zealand sheep farms: A systematic review, meta-analysis and bio-economic model

Dystocia contributes to lamb and ewe mortality in the periparturient period but impacts for extensive sheep production systems remain poorly understood. Here we show that lamb and ewe mortality associated with dystocia has important impacts on sheep production in Australia and New Zealand, and quantify financial impacts for the Australian sheep industry. A systematic review of the literature identified 11 publications published since 1990 that reported sheep mortality due to dystocia in Australia or New Zealand. Assumptions for ewe breeding flock structure and reproductive performance were based on Australian sheep industry data. The proportion of lamb mortality attributable to dystocia (including stillbirths and perinatal deaths with evidence of hypoxic injury) pooled across all studies (pooled proportional mortality ratio) was 47 % (95 % Confidence Interval (CI): 38, 55). Pooled proportional mortality ratio for Australian studies was 53 % (95 %CI: 47, 60), and for New Zealand studies was 35 % (95 %CI: 19, 51). Pooled proportional mortality ratio was similar for lambs born to Merino and non-Merino ewes, although more data are needed to determine effects of ewe breed independent of other factors. Pooled proportional mortality ratio was higher for single lambs (59 %; 95 % CI: 55, 63) than twin (47 %; 41, 54) or triplet (49 %; 46, 52) lambs. However, the number of dystocia-associated mortalities is higher for twin-born lambs than for singles because total mortality is higher for twin-born lambs. It is estimated that approximately 7.7 million lamb deaths and 297,500 ewe deaths per year are attributable to dystocia in Australia for the national flock of 38 million breeding ewes. The whole-farm bio-economic Model of an Integrated Dryland Agricultural System (MIDAS) was used to determine the impacts of dystocia-associated ewe and lamb mortality on Australian farm profit. Dystocia is estimated to reduce Australian national farm profit by AU$780 million or $23.00 per ewe mated based on an assumed lamb sale price of AU$6.50 per kg carcass weight. These estimates do not include the costs of reduced productivity for surviving ewes and lambs, intervention, post-farmgate impacts, delayed genetic progress, or impacts on animal welfare and access into sheep meat and wool markets. Reducing dystocia through improved genetics and sheep management will improve animal welfare and farm profit.

Expression quantitative trait loci in sheep liver and muscle contribute to variations in meat traits

Background

Variants that regulate transcription, such as expression quantitative trait loci (eQTL), have shown enrichment in genome-wide association studies (GWAS) for mammalian complex traits. However, no study has reported eQTL in sheep, although it is an important agricultural species for which many GWAS of complex meat traits have been conducted. Using RNA sequence data produced from liver and muscle from 149 sheep and imputed whole-genome single nucleotide polymorphisms (SNPs), our aim was to dissect the genetic architecture of the transcriptome by associating sheep genotypes with three major molecular phenotypes including gene expression (geQTL), exon expression (eeQTL) and RNA splicing (sQTL). We also examined these three types of eQTL for their enrichment in GWAS of multi-meat traits and fatty acid profiles.

Results

Whereas a relatively small number of molecular phenotypes were significantly heritable (h² > 0, P < 0.05), their mean heritability ranged from 0.67 to 0.73 for liver and from 0.71 to 0.77 for muscle. Association analysis between molecular phenotypes and SNPs within ± 1 Mb identified many significant cis-eQTL (false discovery rate, FDR < 0.01). The median distance between the eQTL and transcription start sites (TSS) ranged from 68 to 153 kb across the three eQTL types. The number of common variants between geQTL, eeQTL and sQTL within each tissue, and the number of common variants between liver and muscle within each eQTL type were all significantly (P < 0.05) larger than expected by chance. The identified eQTL were significantly (P < 0.05) enriched in GWAS hits associated with 56 carcass traits and fatty acid profiles. For example, several geQTL in muscle mapped to the FAM184B gene, hundreds of sQTL in liver and muscle mapped to the CAST gene, and hundreds of sQTL in liver mapped to the C6 gene. These three genes are associated with body composition or fatty acid profiles.

Conclusions

We detected a large number of significant eQTL and found that the overlap of variants between eQTL types and tissues was prevalent. Many eQTL were also QTL for meat traits. Our study fills a gap in the knowledge on the regulatory variants and their role in complex traits for the sheep model.

Feeding lambs proportional mixtures of lucerne (Medicago sativa) and forage brassica (Brassica napus) grown under warm and dry conditions

Context Metabolisable energy (ME) and crude protein (CP) concentrations of forages are key determinants of lamb performance during pasture-based finishing. However, forage species often have unbalanced proportions of ME and CP, which can lead to below-optimum performance of lambs. This may be a problem with maturing lucerne (Medicago sativa L.) swards during dry summer conditions, and is a major challenge faced by grazing industries in Mediterranean environments. Aim We investigated whether two summer forages, lucerne and forage brassica (Brassica napus L. cv. Winfred), with differing ME and CP concentration could improve the growth of maternal-composite lambs when offered in mixtures compared with either forage fed alone. Methods A randomised complete block experiment with five treatments and 10 replicate animals per treatment was conducted in an animal house at Hamilton, Victoria, from February to March 2014. The treatments were 100% lucerne, 75% lucerne : 25% brassica, 50% lucerne : 50% brassica, 25% lucerne : 75% brassica, and 100% brassica on a dry-matter basis and fed to lambs. The lucerne and brassica were harvested daily and chopped to ~3 cm length before mixing and feeding. The lambs were adapted for 4 weeks before the start of the experimental phase. Key results Fasted liveweight gain of lambs increased linearly with an increasing proportion of brassica and a decreasing proportion of lucerne in the diet; no mixture performed better than brassica alone. Conclusions Under the warm and dry conditions of this experiment, the ME of lucerne was more limiting to lamb growth than its CP concentration. Implications The results suggest that a small increase in ME supply could improve the performance of lambs grazing a maturing lucerne sward during dry summer conditions. Further research is warranted into improving lamb growth and feed efficiency from lush lucerne and brassica forages.

Effect of grazing different forage systems prior to and during mating on the liveweight, condition score, conception and reproductive rate of maternal-composite ewe lambs

Context Economic modelling identified that mating of ewe lambs for lambing at 1 year of age has the potential to increase the profitability of sheep-production systems in south-western Victoria. In order to optimise reproductive rates, ewe lambs should weigh at least 35–40 kg, have a condition score (CS) of 3.0 at mating, and be gaining weight (100–150 g/day) during mating. However, typical perennial ryegrass (Lolium perenne L.) pastures in south-west Victoria do not support the attainment of these targets without additional supplementation. Aim Our research aimed to determine how grazing summer-active pastures or brassica (Brassica napus L.) forages affects the liveweight, CS, conception and reproductive rate of ewe lambs when offered before and during mating compared with a system using perennial ryegrass plus supplement. Methods A field experiment was conducted at Hamilton, Victoria, Australia, in 2014 and 2016 testing seven forage treatments replicated four times in a complete block design. The treatments were: canola (B. napus, two treatments of different cultivars), forage brassica, lucerne (Medicago sativa L.), chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.) and perennial ryegrass. Key results Ewe lambs grazing canola or forage brassica had higher (P &lt; 0.05) liveweight gains during the pre-mating and mating periods than those grazing the perennial ryegrass treatment (148 vs 75 g/day in 2014, s.e.m. 17; 139 vs 54 g/day in 2016, s.e.m. 17). In 2014, spring-sown dual-purpose canola, lucerne and chicory resulted in higher (P &lt; 0.05) reproductive rates (144–151%) than the perennial ryegrass treatment (103%); forage brassica and plantain gave intermediate results (128% and 129%). Conclusion Brassica forages (including spring-sown canola), lucerne and chicory can support the attainment of key liveweight and CS targets for successful mating of ewe lambs in autumn. Implications Spring-sown canola is therefore a viable alternative forage for use by livestock producers in southern Australia and presents an opportunity to incorporate an alternative income stream in mixed-farming systems.

Utilising dual-purpose crops effectively to increase profit and manage risk in meat production systems

Dual-purpose cropping (sowing crops with the intention of both grazing them during vegetative growth and harvesting grain thereafter) has become a widespread farming practice in southern Australia. This synopsis paper integrates research from a multi-institutional research project conducted at three nodes located near Hamilton (south-western Victoria), Wagga Wagga (southern NSW) and Canberra (ACT), and sets out 11 principles for the effective utilisation of dual-purpose crops in meat production systems to increase profit and manage risk. Dual-purpose crops can be used to overcome feed quality gaps in late summer–autumn or feed quantity gaps in late autumn/winter. They provide large quantities of high-quality forages for grazing in summer, autumn and winter and can provide a substantial contribution to the annual number of grazing days on a farm. Utilisation of the high-quality dry matter provided by dual-purpose crops is most effective when directed at young growing stock for sale or future reproduction rather than reproducing adult ewes. For example, sale weight of yearlings per ewe was increased by 16% in systems at the Canberra node when dual-purpose crops were prioritised for grazing by weaners. Wool production was also increased in systems that included grazing of dual-purpose crops. Grazing crops in winter does not necessarily reduce supplementary feeding costs for winter or spring lambing. Modelling suggests that inclusion of dual-purpose crops does not substantially change the optimum time of lambing for sheep meat systems. Financial analysis of the experimental data from the Canberra node showed that although cash expenses per hectare were increased in the crop-grazing systems, the overall profitability of those systems over the life of the experiment was greater by AU$207/ha.year than that of the pasture-only system. Factors driving improved profitability included income from grain, higher income from meat and wool, and lower supplementary feeding costs. However, increasing the area sown to crop from 10% to 30% of the farm area in this Southern Tablelands system appeared to increase risk. In south-western Victoria, spring-sown canola carried risk similar to or less than other options assessed to achieve ewe-lamb mating weight. It is likely that at least part of the reduction in risk occurs through the diversification in income from the canola produced as part of the system. It was concluded that the grazing of cereal and canola crops for livestock production can be profitable and assist in managing risk.

The impact of ewe lamb mating and different feeding strategies over summer–autumn on profit and risk: a case study in south-west Victoria

Context Mating ewe lambs at ~7 months of age is viewed as a way to increase the profit of sheep farms in south-west Victoria, Australia. For a successful mating and high reproductive rate, ewe lambs need to be of &gt;40 kg liveweight and condition score 3 at mating. The region has a temperate Mediterranean climate, and as such, dry summer pastures do not provide adequate nutrition for the weight gain required over summer and autumn if ewe lambs are to be mated early. There is limited economic information on the whole-farm benefits and risks associated with different feeding strategies for meeting the feed requirements of mating ewe lambs. Aims The aims were to test, for a prime-lamb system, whether profit would be increased by the mating of ewe lambs and whether there would be a reduction in whole-farm business risk. We hypothesised that different forage systems would offer profit and risk advantages over current dry-pasture and supplement systems for growing out ewe lambs. Method The biophysical and economic characteristics of a prime-lamb case-study farm were modelled to examine how six different pasture and forage systems for mating ewe lambs would perform under varying seasonal, price and cost conditions. Systems 1 and 2 were based on perennial ryegrass and subterranean clover pastures. System 1 compared lambing at 2 years of age, and System 2 lambing at 1 year of age. The other four systems simulated the use of different forages on a portion of the farm to grow out the ewe lambs for lambing at 1 year of age: System 3, spring-sown forage brassica rape; System 4, spring-sown winter-type canola; and System 5, lucerne; System 6, as for System 4 but at a higher lamb marking rate. Results and conclusions Lambing at 1 year of age increased profit and reduced business risk compared with lambing at 2 years of age. Use of spring-sown canola or lucerne forage for ewe-lamb mating provided the best returns on capital relative to the risk involved. Use of spring-sown canola reduced variability of annual returns, in part because of the diversification of income received from both lamb and canola. Implications The results of this modelling study indicate that some feed systems can increase farm profit and reduce business risk.

Effect of defoliation on spring-sown winter-type canola (Brassica napus) grain yield, quality and morphology

Context In Australia’s high-rainfall zone (&gt;550 mm/year), winter-type canola (Brassica napus L.) can be sown in spring and grazed as a forage crop during its vegetative phase, producing a canola grain crop in late spring of the second year. The timing, length and intensity of grazing or defoliation that can be imposed on canola before a grain yield penalty occurs remains largely unknown. Aim Our research aimed to determine the impact of grazing spring sown canola during summer and autumn on the subsequent canola grain yield. Methods A paddock-scale field experiment was conducted over 2 years, 2013–14 and 2015–2016, at Hamilton, Victoria, Australia, with two winter-type canola treatments and three grazing–defoliation sub-treatments replicated four times in a replicated block design. The canola cultivars used were Hyola971CL and Taurus in 2013–14 and Hyola971CL and Brazzil in 2015–16. The three grazing–defoliation sub-treatments were: NG, no grazing; VG, grazing with sheep for a 10-week period during the vegetative phase over summer–autumn; RG, grazing with sheep as per the VG sub-treatment and then in the reproductive phase, either cutting the canola for silage in August (2013–14) or grazing with sheep between 28 July and 17 August 2016 (2015–16). Key results The VG sub-treatment resulted in no grain-yield penalty (P &gt; 0.05) relative to NG in either year. In 2014, canola grain yields from VG for Hyola971CL and Taurus were 2.32 and 2.13 t/ha, compared with NG grain yields of 2.66 and 2.19 t/ha. In 2016, grain yields from VG for Hyola971CL and Brazzil were 2.14 and 1.74 t/ha, compared with NG grain yields of 1.87 and 1.90 t/ha. The RG sub-treatment reduced (P &lt; 0.05) canola grain yield by ~65% in 2014 and 80% in 2016 compared with NG and VG. Conclusions Spring-sown winter-type canola can be grazed during summer and autumn in southern Australia with no grain-yield penalty relative to ungrazed canola. However, further grazing or defoliation in winter once bud elongation commences can result in large grain-yield penalties. Implications Spring-sown winter-type canola is a viable forage option for filling the summer–autumn feed gap in southern Australia while also providing a dual-purpose income in mixed-farming systems.

Spring-sown winter-type canola (Brassica napus) as summer–autumn forage for sheep production in southern Australia

Context Filling the summer–autumn feed gap is a key priority for sheep producers in southern Australia’s high-rainfall zone. Aim Our research aimed to determine whether spring-sown winter-type canola (Brassica napus L.) could increase herbage mass and nutritive characteristics during summer and autumn relative to other forage options in southern Australia’s HRZ. Methods A field experiment was conducted at Hamilton, Victoria, Australia, in 2014 and 2016 testing seven forage treatments replicated four times in the complete block design. The treatments were: canola (two treatments of different cultivars), forage brassica (B. napus), lucerne (Medicago sativa L.), chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.) and perennial ryegrass (Lolium perenne L.). Key results Herbage mass and nutritive characteristics of the canola varieties did not differ (P &gt; 0.05) from forage brassica. Herbage mass in March 2014 was 3.35–3.64 t dry matter (DM)/ha for brassicas; 1.05–1.37 t DM/ha for perennial ryegrass, plantain and chicory; and 2.94 t DM/ha for lucerne (P &lt; 0.001, l.s.d. = 1.20). In March 2016, herbage mass was 1.86–2.05 t DM/ha for brassicas and 2.14–2.49 for the other forage treatments (P &lt; 0.05; l.s.d. = 0.47). Brassicas had higher (P &lt; 0.05) metabolisable energy (ME) concentrations and lower (P &lt; 0.05) neutral detergent fibre (NDF) concentrations on most sampling dates than chicory, plantain, lucerne and perennial ryegrass. The crude protein (CP) concentration of the brassica treatments was not different (P &gt; 0.05) from that of the other forage treatments. Concentrations of ME, CP and NDF were very similar between years for the brassicas, with March ME, CP and NDF concentrations of 12.0–13.2 MJ/kg DM, 14.0–20.1% DM and 16.7–23.6% DM. Conclusion Canola provided increased or equivalent levels of herbage mass and nutritive characteristics compared with other forage options in south-western Victoria on most, but not all, sampling dates. However, the annual spring-sowing requirement is a challenge under variable spring-rainfall conditions and may limit productivity if there is poor establishment. Implications Spring-sown canola is a viable alternative forage for livestock producers and offers a potential second income stream in high-rainfall-zone livestock farming systems.

Automated feeding of sheep. 1. Changes in feeding behaviour in response to restricted and ad libitum feeding

Context Automated feeding units allow the recording of individual feeding behaviour of group-housed sheep and provide data for research into feed efficiency. Aim It was hypothesised that measures of feeding behaviour such as the number of non-feeding events, meal size, eating rate and meal duration would change under different levels of feeding. Method Maternal Composite ewes (n = 126, 18 per pen) were fed a hay-based pellet using automated feeding units (2 per pen) for four periods differing in total daily feed allowance (kg/day) and meal allowance (g/meal). Sheep were initially fed ad libitum (meal allowance ~1000 g) for 19 days during an adaptation period, before restricted feeding for 41 days at daily allowances of 40%, 60%, 80%, 100%, 140% and 180% of estimated maintenance requirements, with a meal allowance of ~100 g. These restricted daily allowances were the experimental treatments that were randomly applied to sheep and replicated three times per pen. The daily allowance was then adjusted to 1.4 kg/day (with a ~200 g meal allowance) for all sheep over 5 days, before ad libitum feeding of all sheep for a period of 16 days. All feeding and non-feeding events were recorded. Key results Under restricted feeding, sheep altered the timing of their meals to consume more meals during the early morning after daily allowances were reset at 0000 hours. This change was more pronounced for sheep fed a smaller proportion of maintenance. The number of non-feeding events (~8/day) was not affected by the level of restricted feeding, but meal size was smaller, meal duration was longer and eating rate was lower for sheep fed 40% of their maintenance requirement. Under ad libitum feeding, sheep reverted to a preferred meal size and number of meals, with fewer than two non-feeding events per day, but differences in eating rate remained. Conclusions Sheep feeding behaviours adapt and respond quickly to changes in daily allowance and offered meal size, but the similar number of non-feeding events at different proportions of maintenance feeding suggest that non-feeding events may not reflect levels of hunger. Implications Our observations suggest that sheep are capable of learning and adapting to different levels of feeding and that this may allow for automated feeding systems to supplementary feed larger numbers of sheep under extensive situations.

Technical note: validation of an automated feeding system for measuring individual animal feed intake in sheep housed in groups

The development of feeding systems that can individually measure and control feed intake in a group-housed environment would allow a greater understanding of sheep intake without compromising animal welfare and behavior through the removal of social interactions between sheep. This study validated an automated feeding system for measuring feed intake of individual sheep when housed in groups. Validation of the feeding system was conducted during three separate experiments. The validation sampling involved the activation of four individual “feed events,” whereby four separate samples weighing approximately 50, 100, 200, and 400 g were removed from each feeder, with each feed event being linked to a specific radio frequency identification (RFID) tag. The feeder validation experiments evaluated the ability of the feeding system to 1) create a unique feed event every time a sample of pellets was collected from the feeder, 2) link the feed event to the correct RFID, and 3) accurately record the weight of feed that was manually removed. All feed events were initiated and logged in the feeding system with 100% of the events being linked to the correct test RFID. Concordance correlation coefficients between the feeding system-recorded feed weight and the manually removed weight were 0.99 within all three experiments. There was also no overall and little level-dependent bias between the weights measured by the feeding system and weights measured on the external scales. These results indicate the stability of the feeding system over time and consistency between the feeders within and across the three experiments. In conclusion, the automated feeding system developed for measuring individual animal feed intake was able to detect and record the unique electronic RFID associated with unique feed events and accurately capture the weight of feed removed. Furthermore, there was no change in the accuracy of the system from the start to the end of experimental periods, and the amount of feed removed in the feed event (or meal size) did not impact the accuracy of the results.

Understanding the impact of sire lean meat yield breeding value on carcass composition, meat quality, nutrient and mineral content of Australian lamb

Advances in genomics and technology measuring body composition are now allowing sheep producers to select directly for increased lean meat yield (LMY) using Australian Sheep Breeding Values (ASBV). This experiment evaluated the impact of sire LMY ASBV on carcass composition, meat quality, nutrient and mineral content for lambs reared at pasture and finished in a feedlot. A 1% unit increase in sire LMY ASBV resulted in progeny that were leaner (0.8%) and had less fat (1.0%) on carcass. There was also a 0.2% reduction in the intramuscular fat content, a 3.2 N increase in meat toughness determined by shear force at day 5 ageing, a reduction in the redness of the fresh meat and a lower iron content. It is concluded that Australian sheep producers will need to incorporate ASBVs for other aspects of meat quality when selecting sires with increased LMY to avoid deterioration in meat quality, nutritional content of lamb and fresh meat colour.

Crossbred ewes gain more weight and are fatter than Merino ewes when managed together but similar coefficients predict lamb birthweight and survival

Current Australian ewe management guidelines are based on research from Merino ewes and have been transposed to crossbred ewes. It is unknown whether guidelines developed for Merino ewes are applicable to crossbred ewe production systems. To investigate this, the effect of ewe liveweight and condition score profile during pregnancy on lamb birthweight and survival for Border Leicester × Merino (BLM) crossbreds was compared with Merino ewes. Condition score profiles of 720 Merino and 680 BLM ewes were managed from 50 days after ram introduction to achieve one of four target condition scores at lambing. There were three replicates of the four target condition score treatments and both breeds of ewes were in each plot. By Day 140 after rams in, the BLM ewes were fatter (P &lt; 0.001) and heavier (P &lt; 0.001) than the Merino ewes, despite being managed in the same plots. Liveweight at conception and change in liveweight in late pregnancy of the Merino and BLM ewes had a similar effect on the birthweight and weaning weight of their lambs. However, birthweight and weaning weight of lambs from BLM ewes was less sensitive to ewe liveweight change in early pregnancy. Birthweight survival curves were similar in lambs from Merino and multiple-born lambs from BLM ewes, and the survival of lambs from multiple-bearing BLM ewes responded to manipulation of condition score in a similar pattern to lambs from Merino ewes. Therefore, managing liveweight or condition score of multiple-bearing BLM ewes is likely to improve lamb survival in a similar fashion to lambs from Merino ewes, although the absolute response in survival will be smaller than that achieved in Merino ewes at the same condition score. In addition, it is important to manage liveweight of both single and multiple-bearing BLM ewes during pregnancy to optimise weaning weight of their lambs, as those lambs born to BLM ewes of low liveweight were significantly lighter at weaning.

Offering maternal composite ewes higher levels of nutrition from mid-pregnancy to lambing results in predictable increases in birthweight, survival and weaning weight of their lambs

Management of nutrition during pregnancy for maternal composite ewes has the potential to improve lamb production and survival in prime lamb production systems but existing condition score (CS) guidelines developed for Merinos may not be appropriate for the optimum production of maternal ewes. To address this, three replicated experiments were conducted at two research sites in Victoria and one in Western Australia. Ewes (781–800 per site) were allocated to four CS treatments following pregnancy scanning (~Day 50) and differentially fed to reach approximate targets of CS 2.4, 2.8, 3.2 and 3.6 by lambing. Single and multiple bearing ewes grazed together, and nutritional treatments were applied until the end of lambing after which ewes and lambs were aggregated into management groups containing all treatments. At lambing, maternal ewe liveweight had a range between treatments of 13.7–19.1 kg (average 16.4 kg) and CS varied by 1.1–1.5 of a CS (average 1.24). Across site analysis indicated that lamb birthweight and weaning weight increased with application of higher CS treatments (P &lt; 0.001). There was also an improvement in survival of multiple born lambs with increasing CS at lambing (P &lt; 0.001). Birthweight was significantly related to survival (P &lt; 0.001) at all sites with no significant effect of birth type on lamb survival. Changes in birthweight and weaning weight could be predicted from ewe joining liveweight, ewe liveweight change to Day 90 and ewe liveweight change Day 90 to lambing. The coefficients derived for each of these effects were similar to those found in previous experiments examining Merino and crossbred Border Leicester Merino ewes. The optimum CS targets for multiple bearing maternal composite ewes may be higher than the industry recommended target for Merino ewes based on advantages in lamb survival and weaning weight.

The influence of the level of ewe gestation nutrition and lamb finishing diet on long-chain polyunsaturated fat concentration, antioxidant and mineral status, and colour stability of meat

The influence of ewe gestation nutrition (EGN) and lamb finishing diet (LFD) on muscle essential fatty acid, antioxidant and mineral status and retail colour of meat in F1 progeny lambs were investigated. First-cross Border Leicester × Merino and Maternal–Coopworth Composite ewes (n = 938) were artificially inseminated to nine terminal sires. From this flock, 648 pregnant ewes were selected between Day 41 and Day 49 of pregnancy, producing 72 pregnant ewes from each sire for distribution across six condition-score (CS) groups. Each CS group was balanced for three sires of high, medium and low lean meat yield and ewe breed. Variation in EGN was achieved through pasture allocations and supplementation, to meet three CS (2.5, 3.0 and 3.5) targets at lambing. At lambing, management of EGN ceased and ewes and lambs were given access to similar pasture allocations. Lambs were weaned at 12 weeks of age and backgrounded on pasture before the random allocation from within each block of sire by CS treatment combination, to the following three different finishing diets: high energy–high protein (HEHP); high energy–moderate protein (HEMP) and moderate energy–high protein (MEHP). Moderate EGN (CS 3.0) increased (P < 0.02) muscle C22:6n-3 and decreased (P < 0.04) C20:4n-6 concentrations compared with CS 2.5 and CS 3.5 EGN groups respectively. Redness of meat over the display period was greater (P = 0.005) for CS 3.0 and CS 3.5 EGN regimes than for the CS 2.5 regime. The MEHP diet reduced (P < 0.01) muscle C18:2n-6, C20:4n-6 and total n-6 fatty acid and increased antioxidant (vitamin E, P < 0.01) concentrations compared with HEHP and HEMP diets, but iron concentration was not affected. Differences in dietary vitamin E concentration between MEHP diet and HEHP or HEMP diets are likely to have contributed to increases in muscle antioxidant status. The energy and protein concentration of LFD had no effect on the health claimable n-3 fatty acid concentration in meat.

Sheep residual feed intake and feeding behaviour: are ‘nibblers’ or ‘binge eaters’ more efficient?

Efficient liveweight gain is an important component of profitable livestock systems. In cattle, studies of residual feed intake (RFI) suggest that there are behavioural differences between efficient and inefficient animals; more efficient animals have less frequent, larger feed events. There is limited understanding of the association between feeding behaviour and feed conversion efficiency (measured as RFI) in sheep. We hypothesised that more efficient sheep would have lower daily number of meals but larger meal size than would less efficient sheep and that feeding behaviour would be repeatable between measurements conducted using the same sheep at different ages. Feeding behaviour was monitored at post-weaning (average 311 days) and hogget (average 533 days) age in a single cohort of maternal composite 2014-born ewes undergoing feed-efficiency testing. Feed intake (kg/day) and daily feeding behaviour (meal number, meal size and eating rate) were recorded by using automated feeders. Feed intake was recorded daily for a minimum of 40 days (mean 41 days), following a 14-day adaptation period. Animals were fed a pelleted hay-based diet, with liveweight measured three times per week. At both ages of measurement, a positive (P < 0.01) linear relationship was established between average daily number of meals and RFI. In these cohorts, as daily number of meals increased, RFI became more positive (less efficient). Meal size (kg DM) was also related to RFI (P < 0.05) when measured at the hogget age, with meal size decreasing with an increasing RFI (less efficient animals had smaller meals). These analyses suggest that sheep feeding behaviour, and in particular daily meal number, is associated with feed efficiency.

Dietary choice and grazing behaviour of sheep on spatially arranged pasture systems. 1. Herbage mass, nutritive characteristics and diet selection

Offering livestock dietary choice through access to different pasture species enables livestock to regulate their own feed intake, select for nutrients and minerals, balance rumen health and display natural grazing and foraging behaviours, which could in turn result in increased livestock productivity. An experiment was conducted at Hamilton, Victoria, Australia, to test the hypothesis that offering lambs dietary choice through spatially separated combinations of pasture species would improve lamb performance, relative to lambs with no dietary choice. The experiment tested seven treatments, replicated four times in a randomised complete block design with plot sizes of 1 ± 0.1 ha. The treatments were: 100% perennial ryegrass (Lolium perenne L.) (PR), 100% plantain (Plantago lanceolata L.) (PL), 100% lucerne (Medicago sativa L.) (LU), 50 : 50 perennial ryegrass/plantain (PR + PL), 50 : 50 perennial ryegrass/lucerne (PR + LU), 50 : 50 plantain/lucerne (PL + LU) and 33 : 33 : 33 perennial ryegrass/plantain/lucerne (PR + PL + LU). In the multiple species swards, the pasture species were separated spatially (by area). Plots were grazed by weaned lambs between March and June 2011. Pre-grazing herbage mass during March and April were highest (P < 0.05) from the lucerne and lowest (P < 0.05) from the plantain, with lucerne producing 4.5–5.5 t DM/ha during this time, whereas the perennial ryegrass and plantain produced 3.5–3.9 t DM/ha and 2.3–3.0 t DM/ha, respectively. Herbage disappearance (calculated estimate of feed intake) was highest (P < 0.05) from the lucerne and lowest (P < 0.05) from the plantain during March and April. Leaf crude protein between the perennial ryegrass and plantain did not differ (P > 0.05) and were lower (P < 0.05) than the lucerne, but the perennial ryegrass and plantain had higher (P < 0.05) leaf on offer (kg DM/ha). Plantain leaf had higher (P < 0.05) Fe, Zn, Co, Ca and S than the perennial ryegrass leaf and higher (P < 0.05) Se, Cu, Mg, Na and Cl than the perennial ryegrass and lucerne leaf and a more negative (P < 0.05) dietary cation : anion difference. The agronomic data presented in this paper provides support for the hypothesis, with lambs showing dietary preferences between pasture species and morphological components, and forms to basis for why these preferences exist. The two subsequent papers show how offering lambs dietary choice affected the performance of male lambs to slaughter and female lambs to first joining.

Dietary choice and grazing behaviour of sheep on spatially arranged pasture systems. 2. Wether lamb growth and carcass weight at slaughter

Dry matter production and nutritive characteristics of the pasture feedbase during autumn are key drivers of profitability in Australia’s prime lamb systems. An experiment was conducted to test the hypothesis that offering lambs dietary choice through spatially separated combinations of perennial ryegrass (Lolium perenne L.), plantain (Plantago lanceolata L.) and/or lucerne (Medicago sativa L.) improves the post-weaning liveweight gain, condition score (CS), pre- and post-slaughter carcass characteristics and reduces the internal parasite burdens of wether lambs finished to a slaughter weight over autumn, relative to lambs offered no dietary choice. The experiment tested seven treatments, replicated four times in a randomised complete block design with plot sizes of 1 ± 0.1 ha. The treatments were: 100% perennial ryegrass (PR), 100% plantain (PL), 100% lucerne (LU), 50 : 50 perennial ryegrass/plantain (PR + PL), 50 : 50 perennial ryegrass/lucerne (PR + LU), 50 : 50 plantain/lucerne (PL + LU) and 33 : 33 : 33 perennial ryegrass/plantain/lucerne (PR + PL + LU). Plots were grazed by weaned lambs between March and June 2011. The lambs had been born between 3 August and 7 September 2010 and were derived from either Coopworth composite dams joined to Coopworth maternal sires or from Merino dams (Toland or Centreplus bloodlines) joined to Border Leicester sires. Backgrounding the lambs on a pasture system that contained lucerne during the lactation to weaning period increased (P < 0.05) liveweight at slaughter by 8% and hot carcass weight by 10%, relative to lambs backgrounded on perennial ryegrass. Finishing lambs on the LU treatment between weaning and slaughter increased (P < 0.05) liveweight at slaughter by 11%, CS at slaughter by 0.3 units, hot carcass weight by 16%, carcass CFAT (measured over the loin) by 2.5 mm, carcass eye muscle depth by 1.1 mm and carcass GRFAT (total tissue depth at 11/12th rib, 11 cm from mid line) by 3.8 mm, relative to lambs finished on the PR treatment. Finishing lambs on LU + PR, LU + PL or LU + PR + PL did not (P > 0.05) improve any of the measured parameters, relative to finishing lambs on the LU treatment. The PL and PR treatments did not differ (P > 0.05) in liveweight at slaughter, CS at slaughter or carcass characteristics, but the PL treatment had lower (P < 0.05) liveweight gain than the PR treatment during the first 2 weeks of the experiment (39 g/day vs 330 g/day), which was later partially compensated for. Our hypothesis has not been supported given that the use of spatially arranged mixes resulted in no improvement in liveweight gain, CS, carcass characteristics or internal parasite burdens relative to the comparable single species sward.

An integrated sensory, consumer and olfactometry study evaluating the effects of rearing system and diet on flavour characteristics of Australian lamb

Producing lamb with good eating quality – flavour, tenderness and juiciness – is essential for consumer satisfaction. Forages such as lucerne and plantain can play an important role in sustainable lamb production; however, it is important to ensure that these feeds do not introduce undesirable flavours. We evaluated the potential for backgrounding (post-weaning) and finishing diets (11 weeks pre-slaughter) to affect lamb eating quality. Lambs were backgrounded on either (1) a combination of three cultivars of perennial ryegrass or (2) a combination of lucerne, ryegrass and fescue and then finished (76 days) on one of three forages; (1) perennial ryegrass (Lolium perenne), (2) lucerne (Medicago sativa) or (3) plantain (Plantago lanceolota). After slaughter, striploin (M. longissimus thoracis et lumborum) and topside (M. semimembranosus) muscles were removed. Grilled striploins were subjected to consumer acceptance studies and quantitative descriptive analysis by a trained sensory panel. Grilled meat from lambs finished on lucerne and plantain was equally or more acceptable than on ryegrass, with no negative impacts on flavour. The backgrounding system affected flavour attributes as well as tenderness. Grilled lamb volatiles were comprehensively characterised by gas-chromatography-mass spectrometry-olfactometry. Specific flavour-related sensory attributes were modelled using semi-quantitative volatile data. Targeted analysis of branch-chained fatty acids, 4-methylphenol and 3-methylindole indicated no significant effects of backgrounding regime or finishing feed. We conclude that neither lucerne nor plantain had negative impacts on lamb flavour although different combinations of backgrounding and finishing feeds may affect lamb tenderness.

Economic value of pregnancy scanning and optimum nutritional management of dry, single- and twin-bearing Merino ewes

The nutritional requirements of twin-bearing ewes are ~25% greater than those of ewes with single fetuses during late pregnancy and nearly twice those of non-pregnant ewes. Underfeeding ewes, resulting in liveweight loss during late pregnancy, can have adverse effects on the production and survival of both the lamb and the ewe, and improving twin-lamb survival is critical to improving the overall reproductive performance of the National Merino flock. Scanning for pregnancy status and litter size allows for more precise management of the nutrition of the ewe flock according to the different nutritional needs of dry, single- and twin-bearing ewes. In the present paper, we tested the hypothesis that it is profitable to identify pregnancy status and litter size, and the optimum nutrition profiles are different for dry, single- and twin-bearing ewes. We tested this by examining a range of nutrition strategies for flocks where only the dry ewes were identified, or for flocks where the single- and twin-bearing ewes were identified. A MIDAS model set up for the Hamilton region in south-western Victoria was used for this analysis as it represents the whole flock and it includes a powerful feed-budgeting module that optimises animal and pasture management across the whole farm. The survival and production of the single- and twin-born progeny was adjusted on the basis of the liveweight profile of the single- and twin-bearing ewes. Our hypothesis was supported and profitability was increased by approximately AU$4630/farm or AU$0.80/ewe, by scanning ewes for pregnancy status and litter size, and the optimum liveweight profiles were different for dry, single- and twin-bearing ewes. The majority of the increase in profit was due to identifying litter size and being able to differentially manage the single- and twin-bearing ewes. When ewes are scanned for pregnancy status and litter size, the most profitable combination of profiles involves all ewes losing 4 kg in early pregnancy and single-bearing ewes regaining the 4 kg to lamb at their standard reference weight, twin-bearing ewes gaining 8 kg to lamb above their standard reference weight and dry ewes losing a further 4 kg to be 8 kg lighter than their standard reference weight at lambing time.

Modelling the potential of birdsfoot trefoil (Lotus corniculatus) to reduce methane emissions and increase production on wool and prime lamb farm enterprises

In Australia in 2011 the Federal government introduced a voluntary offset scheme called the Carbon Farming Initiative, which allows farmers to receive carbon credits when they reduce or sequester greenhouse gas emissions. Various mitigation options have since been explored for their potential to reduce on-farm greenhouse gas emissions. Among these is the use of alternative pastures that lower methane (CH4) production of grazing animals such as Lotus corniculatus, a legume that contains condensed tannins that inhibit the formation of CH4 in the rumen. Lotus has other benefits for sheep production such as increased wool growth, liveweight gain and fecundity. This study modelled the potential emission, production and economic outcomes for wool and lamb enterprises that incorporate lotus in their pastures, evaluating the impact of existing farm productivity, lotus intake and carbon price. Depending on the amount of lotus consumed and the CH4 reduction rate, CH4 emissions fell by 0.02–0.38 t carbon dioxide equivalents (CO2e)/ha and 0.05–0.48 t CO2e/ha on wool and prime lamb enterprises, respectively. At a price of $6/t CO2e potential offset income attributable to use of lotus across all enterprises was $0.12–2.91/ha. Increases in income from increased productivity were 15–30 times greater than from potential carbon offset income. Income was driven by the amount of lotus dry matter intake and the subsequent production benefits. Over a 10-year period prime lamb enterprises generated up to $50/ha in profit by using lotus, due to increased liveweight gain and fecundity. In most modelled scenarios wool enterprises would not cover the cost of lotus pasture establishment. This research demonstrated that 18–23% and 37–46% of lotus intake within the diet was required to generate production enough to cover pasture establishment costs on prime lamb and wool enterprises, respectively. Potential carbon offset income would not be sufficient for farmers to establish lotus without the productivity benefits. While extra profit may be gained on prime lamb enterprises through the use of lotus, problems with persistence must first be overcome for lotus to be adopted on farms.

Does producing more product over a lifetime reduce greenhouse gas emissions and increase profitability in dairy and wool enterprises?

Australian agriculture generated 15% of national greenhouse gas emissions (GHGE) in 2011, with CH4 and N2O accounting for 12 and 3% of national emissions, respectively. In 2011, the Australian government introduced a voluntary carbon offset scheme called the Carbon Farming Initiative, which enables farmers to earn carbon credits by lowering GHGE or sequestering carbon. One way of reducing emissions is to decrease the number of replacement animals required on-farm and increase the amount of product that animals produce across their lifetime. This study explores two options for reducing GHGE over an animal’s lifetime: (1) changing from an annual calving system to extended lactation system on dairy farms; and (2) increasing the longevity of ewes on wool enterprises to produce an extra year of wool and offspring. The biophysical models DairyMod and GrassGro were used to simulate the dairy and wool enterprises, respectively, and GHGE were calculated using the Australian National Inventory methodology. Extended lactation produced lower total emissions and emissions intensity (t CO2e/t milk fat plus protein) than annual calving and also resulted in higher operating profits. The GHGE from increasing longevity on sheep enterprises was similar to the baseline scenario, largely as a result of similar stocking rates. Extended lactation had greater potential of reducing emissions than increasing longevity on wool enterprises because there was a larger increase in the production of milk fat plus protein across cows’ lifetimes, as well as greater reductions in the number of replacement animals required on the enterprise. This research demonstrated that the profitability of farm enterprises would be driven more by productivity than claiming carbon offsets from these management changes.

Carcase weight and dressing percentage are increased using Australian Sheep Breeding Values for increased weight and muscling and reduced fat depth

Pre-slaughter live weight, dressing percentage, and hot standard carcase weight (HCWT) from the 2007, 2008, 2009 and 2010 birth-years of the Information Nucleus Flock Lambs (n=7325) were analysed using linear mixed effects models. Increasing the sire breeding value for post-weaning weight (PWWT), and c-site eye muscle depth (PEMD), and reducing the sire breeding value for fat depth (PFAT) all had positive impacts on HCWT. The magnitude of the PWWT effect was greater in pure bred Merinos compared to Maternal and Terminal sired progeny. The improved HCWT resulting from increased PEMD was entirely due to its impact on improving dressing percentage, given that it had no impact on pre-slaughter live weight. There were marked differences between sire types and dam breeds, with pure-bred Merinos having lower pre-slaughter weight, reduced dressing percentage, and lower HCWT than progeny from Terminal and Maternal sired lambs or progeny from Maternal (1st cross) dams.

Mouse models for Aicardi-Goutières syndrome provide clues to the molecular pathogenesis of systemic autoimmunity

Aicardi-Goutières syndrome (AGS) is a hereditary autoimmune disease which overlaps clinically and pathogenetically with systemic lupus erythematosus (SLE), and can be regarded as a monogenic variant of SLE. Both conditions are characterized by chronic activation of anti-viral type I interferon (IFN) responses. AGS can be caused by mutations in one of several genes encoding intracellular enzymes all involved in nucleic acid metabolism. Mouse models of AGS-associated defects yielded distinct phenotypes and reproduced important features of the disease. Analysis of these mutant mouse lines stimulated a new concept of autoimmunity caused by intracellular accumulations of nucleic acids, which trigger a chronic cell-intrinsic antiviral type I IFN response and thereby autoimmunity. This model is of major relevance for our understanding of SLE pathogenesis. Findings in gene-targeted mice deficient for AGS associated enzymes are summarized in this review.

Plantain (Plantago lanceolata L.) and perennial ryegrass (Lolium perenne L.) as pregnancy and lactation feed for ewes joined at 8 months of age

Ewe nutrition during pregnancy and lactation is a key determinant of ewe and lamb performance. A paddock-scale field experiment in western Victoria, Australia, tested the hypothesis that grazing maiden ewes on plantain (Plantago lanceolata L.) from mid-pregnancy until lamb weaning (July 2010–January 2011) would increase ewe liveweight and condition score during this period, reduce worm egg counts, and increase lamb liveweights at birth, marking and weaning, relative to tetraploid perennial ryegrass (Lolium perenne L.), but that further increases would be achieved by offering a spatially arranged sward of plantain and perennial ryegrass. The experiment tested three treatments: plantain (PL), perennial ryegrass (PR), and a 50 : 50 (by area) spatially separated mixture of perennial ryegrass and plantain (PR + PL). Plots were ~1 ha in size arranged in a randomised complete block design with four replications. The ewes were Coopworth composites joined at 8 months of age. Feed-on-offer levels (kg DM/ha) did not differ (P > 0.05) between treatments, with 2.3–3.0 t DM/ha being available pre-grazing. Twin-bearing ewes had higher (P < 0.05) liveweights when offered PR + PL compared with PR or PL at late-pregnancy and higher (P < 0.05) liveweights than PR but not PL (P > 0.05) at lamb marking. At weaning, single-born lambs were heavier (P < 0.05) on PR than PR + PL, with the PL being intermediate. There were no other significant differences (P > 0.05). This experiment has found that feeding plantain to ewes during pregnancy and lactation, or offering ewes spatially separated mixes of plantain and perennial ryegrass, offers no clear liveweight or worm egg count improvement for ewes and lambs relative to a tetraploid perennial ryegrass under Western Victorian conditions.

The economic benefits of providing shelter to reduce the mortality of twin lambs in south-western Victoria

Achieving higher lamb weaning percentages by reducing lamb mortality can improve the profitability of sheep enterprises. In this paper we estimated the financial benefits from providing shelter to reduce the mortality of twin lambs in self-replacing Merino or dual-purpose Merino flock enterprises in south-west Victoria. A whole-farm bio-economic model (MIDAS) was initially used to estimate the increase in profit from reducing mortality of twin lambs and a second analysis included the costs of using perennial grass hedges to provide the shelter during lambing. The economic value of providing shelter was tested at three rates of twinning (10, 30 and 50%), three rates of mortality without shelter (70, 50 and 30%) and two levels of reduction in lamb mortality by providing shelter (25 and 50% reduction). A sensitivity analysis to wool and lamb prices, costs of establishing the grass hedges and stocking rates in the shelter area were also tested. Overall, more than 2500 scenarios were tested. Across the range of twinning rates and levels of twin mortality tested, at standard wool and meat prices, providing shelter to the dual-purpose Merino ewe flock was always profitable ($0.05 to 11.35/ewe) and the profits from providing shelter to the self-replacing Merino ewe flock were generally lower ($0.15 to $6.35/ewe). The impacts of changing wool and lamb prices depended on enterprise type, whereas the costs of establishment of the hedges or stocking rate of ewes in the hedge area during lambing had little impact on profitability. The main factor that determined the economic return from shelter was the reduction in mortality provided by the shelter but the proportion of twin-bearing ewes in the flock and the base rate of lamb mortality without shelter was also important. Overall, based on the assumptions used, we conclude that the profitability of many sheep enterprises lambing during frequent high chill weather conditions in temperate areas of south-eastern Australia could be improved by providing low cost shelter for twin-bearing Merino ewes lambing from July to September.

A survey of post-weaning mortality of sheep in Australia and its association with farm and management factors

A cross-sectional telephone survey of post-weaning sheep management and mortality was conducted involving 1410 farmers from across Australia. The average reported post-weaning mortality was 4.6%. Mortality was greatest in Queensland and Western Australia, and least in New South Wales, Victoria, and South Australia. Weaner mortality was also greater in the pastoral zone than in the sheep–cereals or high-rainfall zones. Overall, 44% of farms had mortality identified as ‘high’, exceeding the suggested benchmark of ≤4% per annum. High mortality was reported on 50% and 32% of farms with predominantly Merino and crossbred weaners, respectively. There was no statistically significant association between high mortality and the main month of lambing for a flock. Larger sheep flocks, flocks with a smaller proportion of weaners, and farms of smaller area were associated with a greater likelihood of high weaner mortality. The odds of high mortality in weaner flocks that were routinely separated according to bodyweight or condition score was half that of flocks that were managed as one group. Overall, 84% of farmers regularly provided supplementary feed to weaner sheep, but the kind of supplement offered and the proportions of farms routinely supplementing differed between states and sheep production zones. Only high-protein supplementary feeding was associated with lower odds of high mortality. This survey confirms that poor post-weaning survival remains a widespread issue for the Australian sheep industry but identifies farm and management factors associated with reduced weaner mortality.

Reproductive performance in the Sheep CRC Information Nucleus using artificial insemination across different sheep-production environments in southern Australia

The present paper covers reproductive performance in an artificial-insemination (AI) program of the Sheep CRC Information Nucleus with 24 699 lambs born at eight locations in southern Australia across five lambings between 2007 and 2011. Results from AI with frozen semen compared well with industry standards for natural mating. Conception rates averaged 72%, and 1.45 lambs were born per ewe pregnant for Merino ewes and 1.67 for crossbreds. Lamb deaths averaged 21% for Merino ewes and 15% for crossbreds and 19%, 22% and 20% for lambs from ewes that were mated to terminal, Merino and maternal sire types, respectively. Net reproductive rates were 82% for Merino ewes and 102% for crossbreds. From 3198 necropsies across 4 years, dystocia and starvation-mismothering accounted for 72% of lamb deaths within 5 days of lambing. Major risk factors for lamb mortality were birth type (single, twin or higher order), birthweight and dam breed. Losses were higher for twin and triplet lambs than for singles and there was greater mortality at relatively lighter and heavier birthweights. We conclude that reproductive rate in this AI program compared favourably with natural mating. Lamb birthweight for optimum survival was in the 4–8-kg range. Crossbred ewes had greater reproductive efficiency than did Merinos.

Relationships between skin follicle characteristics and fibre properties of Suri and Huacaya alpacas and Peppin Merino sheep

We aimed to quantify the number, type and arrangement of skin follicles in Huacaya and Suri alpaca skin and correlate their follicle characteristics with fibre traits of harvested fibre and compared these relationships with those of Merino sheep. Fibre and skin samples were collected from the mid-side of 12 Huacaya alpacas, 24 Suri alpacas and 10 Merino sheep. The mean fibre diameter (MFD ± s.e.) of the Huacaya and Suri were: 35.5 ± 0.9 and 28.3 ± 1.0 μm, respectively. The follicle groups found for alpacas were very different from the normal trio of primary follicles found in sheep and goats. The follicle group of the alpacas consisted of a single primary follicle surrounded by a variable number of secondary follicles. The mean ± s.e. primary follicle density was 3.1 ± 0.3 and 2.7 ± 0.1 follicles/mm2 for Huacaya and Suri, respectively. The mean ± s.e. secondary follicle density (SFD) was 13.7 ± 1.2 and 17.5 ± 0.6 follicles/mm2 for Huacaya and Suri, respectively. The mean ± s.e. ratio of secondary to primary follicles (S/P ratio) was 5.1 ± 0.5 for the Huacaya and 7.3 ± 0.2 for the Suri alpacas. The sheep had higher S/P ratios and SFD, lower MFD and produced significantly heavier fleeces. The key correlations found between traits in alpacas include a negative correlation between SFD and MFD (r = –0.71, P = 0.001) and a negative correlation between S/P ratio and MFD (r = –0.44, P = 0.003) and a positive correlation between S/P ratio and total follicle density (r = 0.38, P = 0.010). The study revealed that important relationships exist between alpaca skin follicle characteristics and fibre characteristics. It was the number of secondary follicles in a group that imparts density and a corresponding reduced MFD.

Participation in Lifetime Ewe Management results in changes in stocking rate, ewe management and reproductive performance on commercial farms

Lifetime Ewe Management is an extension program designed to assist sheep producers to improve their understanding of ewe nutrition and to develop the skills and confidence to improve their management. The course is based on a small-group extension model and was developed by the Lifetimewool project as a way to incorporate the research findings, economic modelling and producer guidelines developed by the project. Lifetime Ewe Management commenced in Victoria in the spring of 2006 and by the end of 2010, 221 producers had completed the 2-year program. The changes in knowledge, attitudes, skills, aspirations and management practices of 182 of these participants were examined. Participants of the Lifetime Ewe Management program increased their whole-farm stocking rates by 14%, increased lamb marking percentages by 11–13% depending on enterprise type, and decreased ewe mortality rates by 43%. These improvements resulted from a significant change in the perceived importance of managing ewes to condition-score targets to improve profitability and increases in the ability of participants to condition score ewes, assess pasture quantity and quality and feed budget. These changes were consistent regardless of how innovative the participants were at the beginning of the program. The appeal and success of the program was attributed largely to the small-group model where producers worked with their own flock under the guidance of a skilled facilitator and with access to effective decision-making tools. The Lifetime Ewe Management program design provides a blueprint for future extension programs striving to achieve widespread practice change.

On-farm paddock-scale comparisons across southern Australia confirm that increasing the nutrition of Merino ewes improves their production and the lifetime performance of their progeny

Experiments conducted by Lifetimewool at plot-scale have shown that differences in the maternal liveweight during pregnancy and lactation (liveweight profiles) of individual Merino ewes influences their wool production and reproductive rate as well as the birthweight, survival, weaning weight and lifetime wool production of their lambs in a predictable manner. This study determined whether these impacts of nutrition of the ewe on ewe and progeny performance are measurable on commercial properties across southern Australia at a paddock-scale where ewes were aggregated into flocks with a greater spread of the date of conception and where the liveweight profile of the flocks were managed based on random samples of 100 ewes and liveweight was uncorrected for fleece weight or conceptus. Eighteen paddock-scale experiments at 15 sites were conducted in cooperation with wool producers across Victoria, Western Australia, New South Wales, South Australia, and Tasmania. Each co-operator joined up to 1000 mixed aged adult Merino ewes. The flock was scanned using ultrasound at Day 50 from the start of joining to identify those ewes that conceived during the first 21 days of joining. These ewes were then split at random into two treatments and fed to achieve a target difference in liveweight of 10 kg or ~1 condition score/fat score at lambing. The production of ewes during their year of pregnancy and following their next joining was measured as was the performance of their progeny up to their third shearing. Only the 13 paddock-scale experiments that achieved a difference in liveweight profile at lambing of at least 4 kg were included in the final analysis. In these 13 experiments, increasing the nutrition of Merino ewes during pregnancy clearly increased the clean fleece weight and fibre diameter in ewes and the survival and lifetime wool production of their lambs. In most cases the size of the effect was not significantly different to that predicted by the relationship derived using individual liveweight profiles in the plot-scale experiments. This confirms that managing average ewe liveweight or condition score/fat score profile through better nutrition will lead to predictable increases in the performance of ewes and their progeny performance under commercial conditions and validates the use of the plot-scale relationships in economic analyses.

Evaluation of the impact of Lifetimewool on sheep producers

Lifetimewool was a national project that began in 2001 to develop profitable ewe feeding and management guidelines for wool producers across southern Australia. By 2005, the project included communication and adoption activities. Rigorous communication, adoption and evaluation plans were used to maintain focus on its objectives and to measure impacts. Evaluation was an integral part of the project’s development and allowed the project to gain a clear idea of its impact. The project aimed to influence at least 3000 producers nationally to change the management of their ewe flock by the adoption (or part thereof) of Lifetimewool messages and guidelines. More specifically, the project aimed to ‘cross the chasm’ and target producers that were deemed to be in the ‘early adopter’ and the ‘early majority’ segments. The project surveyed sheep producers, sheep industry consultants and sheep industry extension practitioners at the beginning and end of the project to gauge the change in knowledge, attitudes, skills and aspirations of wool producers over the life of the project. Results from the survey of sheep producers in 2008 indicate that the project achieved its aim. About 12% (~3000) of sheep producers nationally have changed practice due to information received from Lifetimewool since 2005. Many other producers have been affected through their increase in knowledge, belief and skills, and market segmentation of the audience shows that the project was successful in ‘crossing the chasm’. The strategies employed by the project to initiate change (i.e. using private consultants and extension professionals as a pathway to adoption, and involving producers, consultants and extension professionals in the development of the Lifetimewool key messages and tools) were validated. The survey results and analysis provided baseline data for future livestock management projects to build on producers’ progress towards practice change. The present paper looks at how the Lifetimewool’s evaluation plan provided a focus for and demonstrated meeting its objectives. In doing so, this paper also seeks to better understand the adoption process.

Successful adoption of new guidelines for the nutritional management of ewes is dependent on the development of appropriate tools and information

Low rates of adoption of innovations in sheep management have been blamed on the poor targeting of messages, low relative advantage of the innovation, a focus on awareness-raising activities rather than adoption activities, poor ‘packaging’ of information and few effective tools to aid decision making. Lifetimewool, a national project that developed management guidelines for Merino ewes specific to regions and different times of lambing, used a ‘review and improve’ process to identify areas of interest, level of knowledge and the skills required by different sectors of the audience to adopt the new recommendations for ewe management. To match these needs and to effectively communicate information from Lifetimewool, a combination of simple and complex tools were produced which were practical, effective, regionally specific and credible. All of the products were designed as a ‘family’ in terms of design and content, allowing a recognition by the producer that they complemented each other and led producers through logical steps for making decisions on managing and feeding ewes. The average awareness of all tools by consultants and extensionists was almost 90% and average usage rates were above 50%. However, the usage rates varied dramatically between tools and users, for example, 46% of consultants used the feed budget tables compared with 76% of extensionists for a similar awareness. Of 1353 producers surveyed more than 55% were aware of the Lifetimewool tools and average usage within this group was 19% and related to the length of time the tool had been available. An estimated 14 000 producers were aware of tools produced by Lifetimewool. The uptake and use of these tools by the target audiences support our hypothesis that tools of differing complexities are required to cater for individual needs.

The merit of condition score and fat score as alternatives to liveweight for managing the nutrition of ewes

The liveweight profile of Merino ewes is related to the production and profitability of the sheep enterprise, but few producers measure liveweight to manage the nutrition of Merino ewes. In this paper we examine the relationship between changes in liveweight and condition score using data from the Lifetimewool project and compare condition score and fat score as alternative monitoring tools. Analyses of liveweight and condition score data from 15 flocks of Merino ewes representing a range of different genotypes and environments showed that the relationship between change in liveweight and condition score was on average 9.2 kg per unit change in condition score or 0.19 times the standard reference weight of the flock. In two experiments experienced operators were used to estimate the condition score and fat score in over 200 ewes and accredited ultrasound scanners measured the eye muscle and fat depth at the C site in the same ewes. All assessments were repeated several times in random order. Within 24 h of the assessments the sheep were slaughtered at local abattoirs where the tissue depth at the GR site was measured on the hot carcasses. Both condition score and fat score were highly repeatable though subject to operator bias. They were related to each other and to the objective measures of fat and eye muscle depth at the C site. However, 95% of sheep below condition score 2.5 had a tissue depth (muscle and fat) at the GR site ≤3 mm, by definition equal to fat score 1. As the condition score of ewes on commercial properties often fluctuates between scores 2 and 3, and small changes in condition score within this range can have large effects on welfare and profit, we conclude that condition score is the most appropriate alternative to liveweight for managing the nutritional profile of ewes.

The national Lifetimewool project: a journey in evaluation

The national Lifetimewool project commenced in 2001 and was funded until 2008. The objective of this project was to develop practical grazing management guidelines that would enable wool growers throughout Australia to increase lifetime production of wool per hectare from ewes. The project achieved its ambitious target of influencing 3000 producers to change their management of ewe flocks by adoption (or part thereof) of Lifetimewool messages and guidelines by 2008. The present paper focuses specifically on the evaluation work that was conducted on the project between 2003 and 2008. It is a noteworthy journey because it provides a case study of the effective implementation of an evaluation plan. The Lifetimewool project used ‘people-centred evaluation’ to help guide the creation of an internal evaluation plan. The six core principles followed were: participation; program logic, a people-centred focus; multiple lines of evidence; reflection and learning and a clearly documented and resourced evaluation plan. These principles were applied from the onset of the project. The Lifetimewool team used the evaluation findings to refine the initial design. Based on learnings from their evaluation journey, they created and modified the extension and communications components of the project. The present paper contends that the evaluation process itself enabled the project team to plan and adjust the course of the project through evidence-based reflection and that this helped ensure that the targets were achieved and demonstrated.

Opportunities for genetic improvement of lamb survival

Data on lamb survival and associated traits involving records from 15 192 lambs, 6308 dams and 284 sires from the Sheep CRC’s Information Nucleus were studied. Lamb survival to 3 days of age and to weaning was 85 and 80%, respectively, and heritability (±s.e.) was 0.014 ± 0.010 and 0.010 ± 0.010, respectively. Of the 14 traits recorded at birth, time taken for the lamb to bleat, rectal temperature and crown–rump length had the highest genetic correlations with lamb survival to weaning (–0.43 ± 0.32, 0.56 ± 0.33 and –0.38 ± 0.36, respectively). Under selection for a multi-trait objective including net reproduction rate (but not lamb survival), survival was predicted to decline genetically by 0.25 lambs weaned per 100 lambs born.year, although this was reversed to a gain of 0.20 lambs weaned per 100 lambs born.year by including the trait in the breeding objective and using 50 half-sib and 50 progeny records per selection candidate. Accuracy of selection for lamb survival was improved to 0.735 with a selection index of lamb survival to weaning, lamb ease, birth coat score, time taken to bleat, rectal temperature and crown–rump length, with the addition of 50 half-sibs and 50 progeny records per candidate. Our results suggest that unless actively incorporated into breeding objectives, lamb survival may genetically decline; however, gains are possible with direct selection using half-sib and progeny records. The addition of indirect selection criteria for lamb survival can further improve accuracy, up to 93.4%, but requires further investigation.

Ultrafast conformational dynamics in cyclic azobenzene peptides of increased flexibility

Structural changes of peptides containing the azobenzene dye 4-aminomethyl-phenylazobenzoic acid (AMPB) are studied with ultrafast spectroscopy. AMPB peptides are a new class of molecules where the photoisomerizable dye azobenzene is linked to the peptide moiety via a flexible methylene spacer. The ultrafast reactions in the femtosecond to nanosecond time domain are investigated for the optical switch AMPB, a linear and cyclic octapeptide, and a bicyclic octapeptide containing an additional disulfide bridge. These molecules with increasing conformational constraints are studied for the cis to trans and the trans to cis photoreactions. For the cis to trans reaction the isomerization of the chromophore occurs fast in the 1-ps range, whereas it is slower (10-ps range) in the trans to cis reaction. In all peptides the structural changes of the chromophore lead to modifications in the peptide structure in the 10-ps-1-ns time range. The results indicate that the chromophore AMPB acts simultaneously as a fast molecular switch and as a sensor for initial conformational dynamics in the peptide. Experiments in the mid-infrared range where the structural changes of the peptide backbone are directly observed demonstrate that the essential part of the structural dynamics in the bicyclic AMPB peptide occurs faster than 10 ns.

[Prospective randomized comparative study of early functional outcome of 2 knee joint endoprosthesis systems--rotation plateau versus fixed polyethylene inlay]

AIM

Different systems are used for total knee arthroplasty (TKA). Compared were a press-fit femur condyle replacement system with fixed tibial PE-inlay versus a rotating tibia component system with an emphasis on the early functional results.

METHOD

Patient selection and the use of the Knee Society Score for this randomized and prospective study were based on the directives for TKA of the german Society for Orthopaedic and Trauma Surgery (DGOT). We examined the patients post-operatively after 1 week, 2 weeks, 6 weeks, 3 months, 6 months, and 1 year.

RESULTS

After 6 weeks an increase of the total knee score could be seen in both groups. The total knee score of the rotating tibia component increased from 93.96 pre-operatively to 113.57 after 6 weeks, to 139.82 after 3 months, to 154.32 after 6 months, and to 159.65 after one year. The total score with the fixed PE-inlay increased from 79.75 to 111.5 after 6 weeks, to 128.25 after 3 months, to 134.08 after 6 months, and to 130.08 after one year.

CONCLUSION

After 6 weeks the implant with the rotating tibia component showed a lasting higher score as compared to the implant with a fixed PE-inlay component using the same early rehabilitation and mobilization techniques.

Mutational studies on HslU and its docking mode with HslV

HslVU is an ATP-dependent prokaryotic protease complex. Despite detailed crystal and molecular structure determinations of free HslV and HslU, the mechanism of ATP-dependent peptide and protein hydrolysis remained unclear, mainly because the productive complex of HslV and HslU could not be unambiguously identified from the crystal data. In the crystalline complex, the I domains of HslU interact with HslV. Observations based on electron microscopy data were interpreted in the light of the crystal structure to indicate an alternative mode of association with the intermediate domains away from HslV. By generation and analysis of two dozen HslU mutants, we find that the amidolytic and caseinolytic activities of HslVU are quite robust to mutations on both alternative docking surfaces on HslU. In contrast, HslVU activity against the maltose-binding protein-SulA fusion protein depends on the presence of the I domain and is also sensitive to mutations in the N-terminal and C-terminal domains of HslU. Mutational studies around the hexameric pore of HslU seem to show that it is involved in the recognition/translocation of maltose-binding protein-SulA but not of chromogenic small substrates and casein. ATP-binding site mutations, among other things, confirm the essential role of the "sensor arginine" (R393) and the "arginine finger" (R325) in the ATPase action of HslU and demonstrate an important role for E321. Additionally, we report a better refined structure of the HslVU complex crystallized along with resorufin-labeled casein.

Photomodulation of conformational states. II. Mono- and bicyclic peptides with (4-aminomethyl)phenylazobenzoic acid as backbone constituent

It has been reported that backbone cyclization of octapeptides with the photoresponsive (4-aminomethyl)phenylazobenzoic acid imparts sufficient restraints to induce and stabilize ordered conformations of the peptide backbone in both the cis- and trans-azo-isomers (L. Ulysse, J. Cubillos, and J. Chmielewski, Journal of the American Chemical Society, 1995, Vol. 117, pp. 8466-8467). Correspondingly, the active-site octapeptide fragment H-Ala-Cys-Ala-Thr-Cys-Asp-Gly-Phe-OH [134-141] of thioredoxin reductase, with its high preference for a 3(10)-helix turn conformation centered on the Thr-Cys sequence, was backbone cyclized with this azobenzene moiety in the attempt to design a photoresponsive system where the conformational states of the peptide backbone are dictated by the configuration of the azobenzene and can be further modulated by the disulfide bridge. Nuclear magnetic resonance conformational analysis of the monocyclic compound clearly revealed the presence of two conformational families in both the cis- and trans-azo configuration. Of the higher populated conformational families, the structure of the trans-isomer seems like a pretzel-like folding, while the cis-isomer relaxes into a significantly less defined conformational state that does not exhibit any regular structural elements. Further restrictions imparted by disulfide bridging of the peptide moiety leads to an even better defined conformation for the trans-azo-isomer, whereas the cis-isomer can be described as a frustrated system without pronounced energy minima and thus with little conformational preferences. Our findings would suggest that this photoresponsive peptide template may not be of general usefulness for light-induced conformational transitions between two well-defined conformational states at least under the experimental conditions employed, even in the bicyclic form. However, trans --> cis isomerization of the bicyclic peptide is accompanied by a switch from a well-defined conformation to an ensemble of possible conformations.

Photomodulation of conformational states. I. Mono- and bicyclic peptides with (4-amino)phenylazobenzoic acid as backbone constituent

The thioredoxin reductase active-site fragment H-Ala-Cys-Ala-Thr-Cys-Asp-Gly-Phe-OH [134-141], which is known for its high tendency to assume an almost identical conformation as in the intact enzyme, was backbone cyclized with the photoresponsive (4-amino)phenylazobenzoic acid (APB) to produce a monocyclic and disulfide-bridged bicyclic APB-peptide. Light-induced reversible cis/trans isomerization occurs at identical extents in both the linear and the two cyclic forms. Nuclear magnetic resonance conformational analysis clearly revealed that in the bicyclic APB-peptide both as a trans- and cis-azo-isomer the constraints imparted by the bicyclic structure do not allow the molecule to relax into a defined low energy conformation, thus making the molecule a frustrated system that flip-flops between multiple conformational states. Conversely, the monocyclic APB peptide folds into a well-defined lowest energy structure as a trans-azo-isomer, which upon photoisomerization to the cis-azo configuration relaxes into a less restricted conformational space. First femtosecond spectroscopic analysis of the dynamics of the photoreaction confirm a fast first phase on the femtosecond time scale related to the cis/trans isomerization of the azobenzene moiety followed by a slower phase in the picosecond time scale that involves an adjustment of the peptide backbone. Due to the well- defined photoresponsive two-state transition of this monocyclic peptide molecule, it represents a model system well suited for studying the ultrafast dynamics of conformational transitions by time-resolved spectroscopy.

Photomodulation of conformational states. Synthesis of cyclic peptides with backbone-azobenzene moieties

The search for photoresponsive conformational transitions accompanied by changes in physicochemical and biological properties led us to the design of small cyclic peptides containing azobenzene moieties in the backbone. For this purpose, (4-aminomethyl)phenylazobenzoic acid (H-AMPB-OH) and (4-amino)phenylazobenzoic acid (H-APB-OH) were synthesized and used to cyclize a bis-cysteinyl-octapeptide giving monocyclic derivatives in which additional conformational restriction could be introduced by conversion to bicyclic structures with a disulphide bridge. While synthesis with H-AMPB-OH proceeded smoothly on a chlorotrityl-resin with Fmoc/tBu chemistry, the poor nucleophilicity of the arylamino group of H-APB-OH required special chemistry for satisfactory incorporation into the peptide chain. Additional difficulties were encountered in the reductive cleavage of the S-tert-butylthio group from the cysteine residues since concomitant reduction of the azobenzene moiety took place at competing rates. This difficulty was eventually bypassed by using the S-trityl protection. Side-chain cyclization of the APB-peptide proved to be difficult, suggesting that restricted conformational freedom was already present in the monocyclic form, a fact that was fully confirmed by NMR structural analysis. Conversely, the methylene spacer in the AMPB moiety introduced sufficient flexibility for facile and quantitative side-chain cyclization to the bicyclic form. Both of the monocyclic peptides and both of the bicyclic peptides are photoresponsive molecules which undergo cis/trans isomerization reversibly.

Photomodulation of the Conformation of Cyclic Peptides with Azobenzene Moieties in the Peptide Backbone

The cisright harpoon over left harpoon trans photoisomerization of the azobenzene building block 4-(4-aminophenylazo)benzoic acid incorporated in a cyclic peptide (see scheme) facilitated a two-state transition of the peptide chain from a rigid constrained conformation in the trans isomer into the largely free conformational space of the cis isomer.