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Australian seedstock cattle breeders have expressed concerns that while there has been genetic improvement in feedlot and abattoir performance of cows, it could have led to a decline in maternal productivity, especially under variable nutritional conditions. This paper describes a substantial project with two components designed to address these issues. The first sub-project was to monitor bodyweight and composition of 7760 young Angus and Hereford cows as they experience variable physiological states (pregnancy and lactation) and seasons. This was conducted on large numbers in seedstock herds. The second sub-project was to monitor more regularly bodyweight, body composition, and calf rearing performance of 500 Angus cows that are genetically divergent for either fat or residual feed intake at two research centres. This also included two levels of nutrition and recording of weekly feed intake of small groups of cows for at least three parities to allow reporting of genotype × nutrition effects on maternal productivity and efficiency. Results from the project are reported in a series of papers with each one having a defined focus.

This paper reports a subset of results from the Beef Cooperative Research Centre-funded Maternal Productivity Project. This research aimed to describe the response of Angus cows of different and divergent genotypes to variable nutritional environments over five breeding seasons. Cows selected for a divergence in either fat depth (HFat vs LFat) or residual feed intake (RFI: HRFI vs LRFI) based on mid-parent estimated breeding values (EBV) for those traits were allocated in replicate groups to either high or low nutritional treatments at two different sites, namely the Vasse Research Centre in Western Australia and the Struan Research Centre in South Australia. The traits reported in this paper include output traits (birth and weaning weight of calves, liveweight change of cows), change traits (change in Rib Fat, P8 fat, eye muscle area and liveweight between specified time points) and reproductive traits [pregnancy rates, percentage calves born alive and days to calving at the days to calving at the second calving opportunity (DC2)]. Having had their first calf, the vulnerability of these young cows to nutritional restriction and how it may adversely affect rebreeding was examined. HFat and HRFI cows were fatter, heavier and had greater eye muscle area than LFat and LRFI, respectively, at all times during the breeding cycle on both levels of nutrition. There was no difference in either days-to-calving or pregnancy rates after the second mating between genotypes. Equally, nutritional treatment had no effect on these traits in this cohort of cows. There was evidence for an implied genetic correlation between Rib Fat EBV, DC2 and pregnancy rates of –0.38 that suggests that selection for leanness may result in reduced fertility of the herd but the effect was not significant herein. As long as producers record the phenotype for both traits and select cows with favourable DC2 as well as low fatness, these problems can be avoided, owing to only 22% of variation in pregnancy rates being explained by DC2 and Rib Fat EBV. Producers can largely be confident that selection for leanness, or increased feed efficiency, has little impact on productivity as long as cows are in adequate body condition to remain healthy and productive.

Context Dual-purpose wheat (Triticum aestivum L.) and canola (Brassica napus L.) crops have been extensively researched for grazing in Australian farming systems, with a focus on grazing by sheep. In some regions, dual-purpose crops have been grazed by cattle, but there have been reports of animal health problems. Aims This paper sought to collate all known experiments conducted throughout Australia of cattle grazing dual-purpose crops, in order to evaluate grazing management options for cattle on dual-purpose crops that result in high growth rates and good animal health outcomes. Methods There were six experiments. In Expts 1–3, cattle were grazed on wheat crops with and without available mineral supplementation of NaCl and MgO in a 1:1 ratio. In Expt 3, lime was also added to the mineral mix. In Expts 4 and 5, dual-purpose crops were grazed in combination with annual pastures to determine whether strategic use of dual-purpose crops could increase whole farm livestock productivity. In Expt 6, cattle were introduced to dual-purpose canola with different periods of adaptation (0, 4 and 7 days). Liveweight gain was monitored regularly to assess differences between adaptation treatments. Key results Liveweight gain was increased by 0–27% when cattle grazing high quality, dual-purpose wheat were provided with mineral supplement. Cattle had an initial lag in growth rate when introduced to dual-purpose canola for grazing and this was not affected by the adaptation strategy used. Cattle that experienced a shorter adaptation period achieved higher weight gains more quickly. After the lag phase, average daily gain (ADG) was ≥2 kg/head.day, with an ADG over the entire grazing period for all treatments of 1.75 kg/head.day. The effect on the farm system was determined by extending the length of the grazing period on the dual-purpose crops. Grazing periods of shorter duration did not increase overall liveweight gains compared with grazing only pasture, whereas extending the period of dual-purpose crop grazing resulted in increased cattle weights. Conclusions Cattle benefit from the addition of mineral supplements when grazing a dual-purpose wheat crop, with a response similar to that previously demonstrated in sheep. Cattle can safely graze dual-purpose canola and achieve high ADG. Inclusion of dual-purpose crops can improve overall cattle performance in the farming system. Implications The potential area for production of dual-purpose crops within the Australian mixed farming zone is large and there may be insufficient livestock numbers within the zone to utilise the potential forage production. Cattle from other regions could be introduced during autumn and winter to realise this large forage potential during a period that is commonly a feed deficit on grazing-only properties. Estimates suggest that up to two million young cattle could be supported for 60 days, increasing liveweight by 90 kg/head.

In southern Australian grazing systems, energy availability typically exceeds energy requirements. Grazing systems are likely to have higher profitability if ewes can utilise this relatively cheap feed by gaining more condition (muscle and fat) and then mobilising it when feed is expensive. The present paper focusses on the importance of genetic merit for fat on the lifetime productivity of the ewe within a commercial operation. The analysis was carried out on a maternal composite stud flock in Holbrook, New South Wales. Ultrasound fat and muscle depth were measured on 2796 ewes as lambs at post-weaning and as adult ewes, to determine the genetic relationship between young and adult body composition. The hypothesis of the paper is that selection for increased fat at young age will improve body condition of adult ewes, which will lead to improved reproduction and potentially reduced requirements for supplementary feeding. Given that the difference in feed cost between times of abundance and shortage is likely to be larger, the system may become more profitable despite being less efficient (owing to increased feed intake). Our results indicated that selection for scanned post-weaning fat and muscle depth in lambs should lead to increased fat muscle and body condition in the breeding ewe because of strong genetic correlation estimates between the post-weaning and adult traits of 0.68–0.99. The influence of body composition traits on reproduction (number of lambs weaned) within the stud flock was weak. However, it is hypothesised that by genetically increasing post-weaning fat depth in ewes, producers could improve profitability by reducing the demands for supplementary feeding.

A population-based epidemiological study was conducted between 2007 and 2011 and involved 78 northern Australian commercial beef-breeding herds and in excess of 56 000 cattle concurrently monitored. Cow reproductive performance was described from the biannual assessment of fetal age and lactation status. Both novel and well established measures of performance were used within four broad country types and included the following: percentage of lactating cows pregnant within 4 months of calving; percentage of cows pregnant within an approximate 12-month reproductive cycle (annual pregnancy); fetal and calf loss between confirmed pregnancy and weaning; percentage of cows contributing a calf at weaning and percentage of non-pregnant females retained for re-mating. The results from the present study described the variation in reproductive performance of commercial beef herds across northern Australia and defined typical and achievable levels of performance. The results from the study suggest that a weaning rate of 66% is a more realistic target level of performance for the Northern Forest, while weaning rates of at least 75–80% are realistic for other country types. Female-cattle performance was much lower in the Northern Forest than in the other country types. In absolute terms, there were 15–20% fewer surviving mated cows contributing a calf at weaning in an annual production year and ~4% more missing pregnant cows, which was associated with the ~20% higher retention of non-pregnant cows for re-mating. The reproductive performance of herds varied substantially among and within country types, with a 20–30% variation in reproduction rates and 5–15% variation in fetal and calf loss for half of the herds in all regions. Further analyses were performed and identified the major causes of this variation and are reported in subsequent papers within this series. The results from the present study appear to suggest that substantial opportunities to increase the reproductive performance of northern beef herds exist, providing that the causes of this variation are able to be identified and alleviated.

As the sophistication of genomic technologies increases and their cost continues to decrease, they are becoming routine tools in livestock breeding programs and production systems. The convergence of electronic measurement systems, cloud-based computing and fast internet enable the use of powerful decision support to help automate and manage livestock production, animal welfare and quality control. The complexity of livestock production systems, combined with the challenges of producing top-quality discretionary products for consumers, means that no single organisation has the range of expertise to support coordinated development of innovation in the relevant supply chains. Collaboration between a broad spectrum of scientists and industry partners is essential to ensure well integrated input to the design and implementation of programs to deliver improvements in efficiency, quality and profit. The need for collaboration among researchers, among research organisations and with end-users has never been more important. Collaboration brings together the skills needed to manage complex problems and enables the sharing of facilities and scarce resources within Australia and internationally. However, the most important component of effective collaboration is the early engagement of end-users to contribute to the design of programs of innovation, to ensure that investment is well targeted and that there is ownership of the problem as well as the solutions delivered through research. Although the potential benefits of effective collaboration are clear, it often takes more than logic to get individuals and organisations to work together. There needs to be a significant financial incentive combined with strong industry leadership and agreed common goals. Allocating resources to establish these foundations for effective collaboration should precede any major research and development funding initiative. The present paper argues that the new face of animal science in Australia should be structured around coordinated programs of research and development, on the basis of effective collaboration.

Context Net reproduction rate defined as number of lambs weaned for joined ewes reflects conception, litter size and the ability of ewes to rear lambs to weaning age. These three attributes can be treated as separate traits for genetic evaluation, allowing breeders to focus selection for each appropriately. Aims The aim of the present paper was to present characteristics of the data, models and genetic parameters estimated from Merino data, along with results demonstrating the predictive capacity of breeding values, for conception, litter size, rearing ability, maternal behaviour and body condition score. Methods Industry data from MERINOSELECT were used to derive phenotypes for conception, litter size and rearing ability traits separately for yearling and adult ewes, along with maternal behaviour and body condition score. Indirect traits provided correlated information, including scrotal circumference, weight, scanned fat and eye muscle depths at up to three ages (post-weaning, yearling and hogget), along with pre-joining weight and condition score for ewes. Co-variances were estimated among the 19 traits included in the analysis. Breeding values were estimated using single step genomic methodology using consensus estimates of genetic parameters, with the predictive capacity of breeding values being estimated using forward-validation. Key results Heritabilities ranged from 0.04 to 0.06 for conception, litter size and rearing ability, and were moderate for maternal behaviour (0.13) and condition score (0.20). Component traits were genetically controlled by some common genes, but with genetic correlations less than 0.5, each component can be selected for independently. Weight, fat depth and muscle depth measures were moderately to highly correlated with body condition score. These body development traits generally had low, favourable genetic correlations with ewe reproductive traits. Conclusions These procedures provide better use of data recorded by breeders subject to both data limitations and opportunities, and provide separate breeding values for conception, litter size, rearing ability, maternal behaviour and body condition score. Implications New breeding values with good predictive ability are now available for the component traits of reproduction. Direct recording data of the traits is required to achieve accuracy of breeding values. Australian Merino breeders are now able to select directly for components of reproduction and specific maternal characteristics.

Heat stress and a high metabolic rate of broilers increase the production of reactive oxygen species, which must be removed by antioxidants to prevent oxidative stress. Selenium (Se) is a potent antioxidant as it is a structural part of glutathione peroxidase (GPx). Dietary supplementation of Se can help reduce the oxidative stress caused by heat-stress conditions. The aim was to evaluate the effect of Se supplementation on the performance and antioxidant status of broilers under heat stress, by using a meta-analysis approach, and to quantify the contribution to heterogeneity of the explanatory variables through a meta-regression procedure. A database of 74 trials was created from 56 published studies that met the following inclusion criteria: papers that reported a measure of effect size, sample size, measure of variability and random procedure. The response variables were GPx and malondialdehyde concentrations, DM intake, average daily gain, and feed conversion rate. Broiler line, Se source, and dosage, heat-stress level, days of experimentation, sample source (blood, liver or meat) and basal Se concentration were considered to be explanatory variables. All statistical analyses were performed in R software, by using the ‘meta’ and ‘Metafor’ packages for meta-analysis and meta-regression respectively. High concentrations of GPx were found in Se-supplemented broilers (>1.76; P = 0.001), in comparison to control groups. However, when the random model was applied to GPx studies, it showed high heterogeneity (I2 = 95.4%), which was reduced (I2 = 61.5) when heat-stress temperature, Se source and its dosage and tissue sample were included as covariates in the meta-regression analysis. The highest standard mean difference of GPx was founded in studies that reported supplementation with inorganic Se sources (2.92), in comparison to supplementation with organic and nano-Se sources (1.66 and 1.44 respectively). The standard mean differences of malondialdehyde and feed conversion rate were significantly lower (

Context Data collected from producers in south-eastern Australia found that the survival of twin-born lambs decreased by 3.5% for each extra 100 ewes in the mob at lambing. Increasing stocking rate by 1 ewe/ha decreased lamb survival by a further 0.7%. These survey findings suggest that lamb survival could be improved by optimising the allocation of ewes to mobs and paddocks at lambing. Aim The present paper reports two experiments. Experiment 1 tested the hypotheses that (1) the survival of twin-born lambs would be greater when ewes lamb in smaller mobs and at lower stocking rates, and (2) the effects of mob size and stocking rate would be greater in Merinos than in non-Merino breeds. Experiment 2 tested the hypothesis that the survival of twin-born Merino lambs would be greater at lower mob sizes when ewes lambed at stocking rates

Research into the growth and development of Thoroughbreds managed on commercial breeding farms is reviewed in this paper. As horses are not meat producing animals, less research has been performed quantifying growth, muscle and bone development than with other production animals. However, variations in growth and development are linked with both value and wastage in young Thoroughbred horses, and can have a long-term impact on racing performance. In Thoroughbred horses, the breeder aims for optimum, or consistent, growth rather than maximum growth. Factors affecting equine growth including environment, nutrition, season and management are discussed in sections covering conception to weaning, weanling to yearling and yearling to 2 years old when horses are nearly fully grown and racing begins. The importance of reference curves for different ages, sex and locations is highlighted. While average daily gain (ADG) declines as the foal gets older, there are seasonal and management influences to consider. Month of birth has an influence on both birthweight and the expected ADG at different ages, which are believed to be related to ambient temperatures and pasture availability for the mare and growing horse. Weaning leads to a growth setback and ADG declines through winter, but increases in spring for the yearling as temperatures and pasture quality and quantity increase. Management factors such as yearling sale preparation are associated with an increase in growth rate, with gains of over 1 kg/day common during the yearling sales preparation process of 6–12 weeks. ‘Home-bred’ horses that do not go to a yearling sale grow at a slower rate but will reach the same endpoint in mature size. Growth of Thoroughbreds is influenced by country, and regions within a country, related to genetics, climate, management practices, market preferences and sale timing. More research is needed into factors affecting growth and development of Thoroughbred horses on commercial farms and the influence differing rates of growth and development have on wastage (such as developmental orthopaedic disease) and commercial outcomes such as yearling sale results and, ultimately, racing performance.

Cow–calf operations constitute the main land-use system in the 18 million ha of well drained tropical savannas of Colombia located in the Orinoco basin. There, numerous sex and age animal categories are present, ranging from suckling calves to old cull cows and steers, which in variable proportions are stocked at one animal unit (AU)/5–10 ha, depending on the ranch and distance from markets. In parallel, early-on farm observations showed that when sown pastures are introduced, graziers recur to opportunistic partial fattening of cull animals for a rapid economic return. The paper reports animal weight gains of cull cows, old steers, and young heifers and yearlings over seven consecutive years grazing on a low fertiliser-input well managed Andropogon gayanus-based pasture and four contemporary years on Brachiaria humidicola. The first 2 years involved three stocking rates (SR; 1.38, 1.85 and 2.32 animal units/ha), whereas a single SR of 1.33 animal units/ha was used for the remainder. A large database that included chemical, and in vitro and in vivo digestibility, values for all forages involved, was used as an input to a mathematical model to estimate methane (CH4) emissions. Estimations were compared with weight-based predictions derived from chamber measurements recorded recently in tropical Australia. Faecal mineral concentration varied little (not significantly) among SR and animal categories. Weight gains of old steers were 4–24% larger than those of cull cows, which, in turn, were larger than those of young steers and heifers (P < 0.01). Excepting one year, the performance of cull cows and old steers did not differ between pastures, confirming earlier on-ranch observations of reasonable weight gains of adult cattle on both pastures. The predicted carcass composition of cull cows and old steers did not differ between pastures either. Over the length of the experiment, cull cows emitted significantly less CH4 than did old steers (129 vs 141 g/day) on A. gayanus, while emissions on B. humidicola amounted to 128 and 137 g/day respectively. Despite between-year differences in animal performance, they are indicative of well managed pasture sustainability. They also show some of the trade-offs involved in the use of contrasting animal categories and pastures in terms of weight performance and predicted carcass composition and CH4 production. The authors expect that the present results will contribute to a rational, science-based discussion of the role of beef systems vis-à-vis environment in a region with limited production alternatives.

The present paper provides an indication (using selection index theory) of the contribution of genetics to a reduction in methane emissions through the current selection for productivity traits (defined as the inherent rate). This is then compared with potential new approaches that incorporate measurements or estimates of methane production as selection criteria. The predicted value of the inherent reduction in methane at a price (all costs and prices are in Australian dollars) of $25/t carbon dioxide equivalent (CO2-e; methane × 25) is $0.38/cow mated per year. The direct value of the estimated annual genetic gain in productivity (about $3/cow mated) is about eight times the value of the savings in methane. The value of the carbon savings doubles to ~$0.75 if methane yield (methane per unit feed intake) is included in the index. This is due to a reduction in methane emissions of 0.78% of the mean (1.20 kg methane/cow mated per year at a carbon cost of $25/t CO2-e) which increases to 1.0% at $50/t CO2-e. If selection is on methane alone, the annual response is ~1.45%, which is valued at $1.39 at a price of $25/t CO2-e. However, adoption is less than 100% at the breeder level, so that realised gains will be less than predicted here.

Potato by-products are frequently fed to cattle in many parts of the World. This paper considered the effect of feeding very high proportions of potato processing waste (PPW) to finishing beef cattle. One-hundred crossbred steers (Continental × British) were assigned to one of five finishing diets where rolled barley was replaced by PPW to give diets containing 0%, 20%, 40%, 60% or 80% PPW in the dry matter. Diets were fed ad libitum for 79, 107 or 135 days before steers were slaughtered and assessed for carcass and meat quality characteristics. Increasing the proportion of PPW in the diet resulted in a positive quadratic response in liveweight gain (P = 0.027). Inclusion level of PPW had no effect on carcass traits, although carcass weights declined linearly from 327 to 312 kg as PPW level in the diet increased (P = 0.016). Overall, effects of increasing the level of PPW on physical and sensory characteristics of meat were small and considered unlikely to affect consumer acceptance. Potentially due to inherent genetic variation in the cattle, some grew more slowly and were on feed for longer. Thus there was a linear decline in liveweight gain (P = 0.001) and a linear increase in grade fat (P = 0.039) as days to finish increased. Steers finished after 107 days had smaller loin eye area and lean meat yield, which resulted in negative quadratic effects for these characteristics (P = 0.014 and 0.024, respectively). We conclude that PPW can fully substitute for rolled barley in finishing diets without any negative implications for growth performance or meat quality and that the effect of days to finish were more important than the effect of the proportion of PPW in the diet.

The present paper focuses on the economic evaluation of the observed differences in maternal productivity of different genetic lines in Angus cattle that were managed under contrasting nutritional regimes typical of southern Australia. Five hundred Angus cows were managed concurrently at two locations in southern Australia. On each site, the cows were managed under the following two different nutritional treatments: High and Low, to simulate different stocking rates. Cows selected for a divergence in either carcass rib-fat depth or residual feed intake based on mid-parent estimated breeding values for those traits, were allocated in replicate groups to either High- or Low-nutrition treatments. By design, the supplementary feeding regime was the same for the High and Low genetic lines to ensure genetic differences were not confounded with management differences. Animal productivity results from the experiment were used as input data to evaluate the economic performance of the four genetic lines under the two nutritional treatments. Two methods were used; the first was a gross-margin calculation of income minus variable costs as AU$ per breeding cow for a 1000-cow herd; the second was a whole-farm linear programming model maximising the gross margin. Stocking rates were optimised by matching the energy requirements for the whole herd with the energy available from pasture and supplementary feed on a representative 700-ha farm. Using the two methods of calculating gross margin (per cow and optimised per hectare), including examination of sensitivity to changes in prices of cattle and supplementary feed, the present study demonstrated that genetically leaner cows due to selection of low fat or low residual feed intake, had gross margins superior to those of genetically fatter cows. They generated more income by selling more liveweight due to heavier weights and higher stocking rates. The results are affected by the management system utilised and some confounding with growth (leaner genetic lines had higher growth estimated breeding values), but will assist producers to make more informed decisions about how to manage animal breeding and nutritional interactions.

The present paper quantifies the variation in selection direction and genetic merit for the 10 Angus seedstock herds that contributed the majority of the data to the industry herd component of the Beef CRC Maternal Productivity Project. Differences in multi-trait selection direction for 17 BREEDPLAN estimated breeding values (EBVs) ranged between 16 and 63 degrees. Important differences among herds for selection direction for individual EBVs were identified. Specifically, some herds had been selecting to increase rib-fat and rump-fat EBV, while others were decreasing them. On the basis of a principal component analysis, 78% of the between herd difference in genetic merit as assessed by 17 EBVs was accounted for by two principal components. For 2000-born calves, the first principal component accounted for 50% of the genetic variation between herds and was most closely associated with days to calving EBV. Of the genetic merit for 2009-born calves, the first principal component accounted for 49% of the between herd variation and had the strongest weightings with BREEDPLAN rib-fat and rump-fat EBVs. The second principal component accounted for 29% of the variation and was most strongly related with BREEDPLAN EBVs for traits gestation length, milk and eye muscle area and 200-, 400- and 600-day weight. The variation at 2009 is consistent with outcomes from qualitative research that hypothesised that the main differences in genetic merit among herds are associated with rib-fat and rump-fat EBVs, but there were also differences in selection emphasis for weight traits. Despite differences in genetic merit among herds being generally small, they will manifest themselves in different productivity outcomes depending on the management system. Seedstock breeders and bull buyers should be aware of this and target their animal selection accordingly.

This paper reports results from a study of ewes in pregnancy and lactation, during which times they grazed at a high versus medium stocking rate and either received or did not receive a pelleted supplement. We measured ewe liveweight, condition score and body composition; intakes by ewes of pasture and supplementary feed; milk production by ewes, and; birthweight, milk intake, liveweight gain and body composition of single and twin lambs. Ewes grazing at the medium stocking rate consumed more pasture in late pregnancy and the intake of supplement significantly reduced pasture intake. Nevertheless, total intakes of organic matter or digestible organic matter were unaffected by supplementation and were significantly higher at the medium stocking rate. Effects of stocking rate on intake persisted into early and mid-lactation, but supplement intake did not affect pasture intake in lactation. Pasture intakes in pregnancy were not markedly different between twin-bearing and single-bearing ewes, nor were pasture intakes in lactation affected by the number of lambs suckled. Ewes suckling twins produced much more milk. There were significant effects of birth type, ewe stocking rate and supplementation on lamb milk intake and liveweight gain. The data were reanalysed by regression, to explore the effects of actual herbage masses and ewe intakes, and the possible effects of non-treatment terms such as ewe age, condition score and dentition score at allocation. These analyses confirmed the above effects of treatment, but also demonstrated that ewes in better condition at the start of the experiment ate less pasture in both pregnancy and lactation, and produced significantly less milk. Ewe organic matter intakes in pregnancy were not related to dentition score at allocation, but in early and mid-lactation were reduced by ~170 g organic matter/day and 280–380 g organic matter/day, respectively, per unit increase in dentition score. There was no significant effect of ewe dentition score on lamb milk intake, but there was a significant penalty of ~19 g lamb liveweight gain/unit increase in ewe dentition score at allocation. Future studies of this kind thus need to include estimates of the condition score and dentition score of ewes when they commence the experiment.

The objective of this study was to investigate the effect of ruminal mechanical stimulating brushes (RMS brush) on rumen fermentation and plasma oxidative stress and subsequent milk production in early lactation dairy cattle in the Australian spring and summer. Two hundred pasture-fed Holstein, Jersey, and Holstein × Jersey multiparous cows were enrolled into Control (no treatment; n = 103) or RMS brush (n = 97) groups in a randomised controlled trial at 26 ± 15 days before calving. The RMS brush group had three brushes/cow administered orally. Each RMS brush consisted of synthetic polymer bristles held in place with a metal component and was enclosed in a paper capsule that dissolved after insertion. Milk yield (MY), bodyweight, and weather data were recorded daily for the first 30 weeks of lactation. Stomach tube rumen fluid samples and plasma were collected monthly for the first 3 months of lactation from a minimum subset of 14 cows from each group. A total of 182 cows calved successfully and 34 cows were removed during the first 30 weeks of lactation. There was no difference in survival between the groups (hazard ratio = 0.952, confidence interval = 0.481–1.88). Rumen, plasma oxidative stress, and milk production measures were not affected by group or the interaction between group and time, with the exception of a mean increase of 304 µM of biological antioxidant potential in the RMS brush cows. The mean temperature humidity index for the first 30 weeks of lactation was

The present work aims to study the effect of species and seasoning time on the physicochemical, microbiological and sensory characteristics of cured legs of sheep and goats. Three cure periods were used: two for sheep and one for goat legs. Legs of lamb were cured for 7 and 8 months whereas legs of goat were cured for 8 months only. Samples were evaluated regarding pH, water activity and indicators of food microbial q uality and safety. A trained panel carried out the sensory analysis, with aroma, texture, appearance and taste being the evaluated parameters. Significant differences were detected between the amount of aerobic mesophiles of the products cured during 7 months and the sheep legs cured during 8 months. Moulds and yeasts were between 1.81 × 106 ± 1.73 × 106 and 3.97 × 106 ± 5.45 × 106 colony-forming units/g, whereas total coliforms varied from 2.80 × 102 ± 4.13 × 102 to 1.31 × 104 ± 2.39 × 104. All samples were negative for toxigenic species. Concerning sensory analysis, hardness and taste persistence were the attributes that presented the highest and the lowest discriminative power, respectively. In general, the panel was able to characterise and distinguish the samples. The cured legs of goats were characterised as harder and as less succulent than those obtained from sheep. Sheep meat with larger time of cure was the brightest, whereas the one with a smaller time of cure was the most succulent. However, goat meat presented higher values of rancid and acid flavour. Sheep meat submitted to longer processing presented the most intense flavour and sheep meat with an inferior cure period presented the lowest intensity in all flavour attributes. This paper describes, for the first time in Portugal, the production and characterisation of cured legs of sheep and goats as a strategy to enhance economic value to good quality products obtained from animals of second category. info:eu-repo/semantics/publishedVersion

Assessments of grazing systems are often constrained by the decisions regarding the management of the grazing systems, including stocking rate, and also the seasonal conditions that occur during the assessment period. These constraints have led to sometimes conflicting results about comparisons of grazing management systems. This paper examines 1-, 4- and 20-paddock (1P, 4P and 20P) grazing management systems to determine how the intensity of grazing management on native pastures influences the financial performance of sheep production systems. The performance of the grazing systems, as part of the Orange EverGraze research experiment, was initially examined using the biophysical data over the 4 years of the experiment and then a more detailed analysis over a longer timeframe was undertaken using the AusFarm simulation modelling software. Flexible management strategies to optimise ewe numbers, sale time of lambs, and adjust ewe numbers based on season, were also assessed to determine which management systems are the most profitable and sustainable. There was higher profit for the 20P grazing system than the 1P system during the experiment. However, when stocking rates were held constant at optimum levels and systems were simulated over 40 years, there was no difference between grazing systems. Modelling strategies used to vary stocking rates showed that flexible management options are better based on optimising ewe numbers and the sale time of lambs rather than changing ewe numbers between years. The sustainability of modelled systems was also assessed using frequency of events where the average herbage mass (0.8 t DM/ha) or ground cover (80%) in autumn dropped below levels that are associated with degradation. Degradation events occurred more so with increasing ewe number than lamb sale time. Overall, the most sustainable systems, when considering profitability and environmental issues, had a stocking rate of 4.2 ewes per ha, with lambs sold in February (2 or 18). Higher stocking rates (5.3 ewes/ha) would need to be run for more intensive grazing management to have higher profitability.

This paper reports on genetic variation in the growth, wool production, carcass, reproduction and the bodyweight and body condition of ewes managed in the Information Nucleus Flock (INF), with a focus on evaluating the potential value of including adult ewe bodyweight and condition change traits in the Australian national sheep genetic evaluations provided by Sheep Genetics. Data were collected over a 7-year period (2007–2013) at eight research sites across southern Australia. Approximately 13 700 ewes were weighed and condition scored with ewes on average mated four times during the study. Adult ewe weight and body condition were recorded across the production cycle and the impact of the physiological status and change in status of the ewe on the genetic relationships with lamb growth, carcass and wool production traits was evaluated. Strong genetic correlations between measurements across the production cycle for adult ewe bodyweight and condition, low heritability of change traits, along with weak genetic relationships between change traits and key production traits suggest that in production systems where nutritional challenges can be managed, change traits provide no improvement to the current practice of using static bodyweight and condition records. The genetic variation in weight and body condition and their genetic relationships with production traits were highly consistent across ages and the production cycle. As a result, the current practice by Sheep Genetics to treat adult weight as a single trait with repeat records is most likely sufficient. However, the inclusion of body condition within the Sheep Genetics evaluation has potential to assist in improving maternal performance, and the feed costs associated with maintaining ewe body condition.

Variation is inherent in any biological system and is a challenge to manage in modern pork-production businesses. In the case of the growing and finishing herd, inherent variation within a population of pigs represents a significant cost as a result of the need to select on farm to meet market specifications, poor matching of diet specifications to nutrient requirements, grading losses, higher pre-weaning mortality, and challenges associated with health management. As a consequence, any management practice that can be applied to reduce variation at the point of sale has the potential to improve the profitability and overall efficiency of a pig enterprise. The present paper considers nutritional interventions of sows during gestation, lactation and the weaning to oestrus interval to minimise inherent variation in the progeny and then pre- and post-weaning nutrition of piglets to limit further variation. Prior to birth, there are many factors that can influence variation in the birthweight and growth potential of the progeny. In gestating sows, dietary energy will not influence variation in birthweight, but supplementation with free arginine and glutamine will reduce variation in birthweight of piglets born and piglets born alive. In lactating sows, maintenance of feed intake to optimise milk production and minimise weight loss of the sow during lactation not only minimises variation in progeny weight at weaning, but enhances subsequent birthweight heterogeneity due to the influence of the sow’s metabolic status on follicle and oocyte quality. Supplementation with dextrose during the weaning to oestrus interval can also reduce variation in birthweight due to a pronounced effect on plasma glucose and insulin concentrations. Prior to weaning, light weight piglets appear to have an enhanced capacity for growth compared with their larger counterparts. To this end, split suckling has been shown to reduce weaning-weight variation, despite no effect on average growth rate or weaning weight for litters with nine piglets or more born alive. Supplemental milk before weaning has reduced variation in weaning weights, but creep feeding has proved equivocal in this regard. Post-weaning, it appears that remedial feeding strategies will do little to improve the growth potential of light-weight pigs, and while high specification diets may contribute to a slight reduction in variation at slaughter, this strategy is unlikely to be economically viable. As with many aspects of commercial pork production, it would seem that the greatest potential to reduce variation in the slaughter weight of market pigs vests with careful management of gestating and lactating sows, with some potential for dietary interventions to further reduce variation in birth and weaning weights.

PigBal is a mass balance model that uses pig diet, digestibility and production data to predict the manure solids and nutrients produced by pig herds. It has been widely used for designing piggery effluent treatment systems and sustainable reuse areas at Australian piggeries. More recently, PigBal has also been used to estimate piggery volatile solids production for assessing greenhouse gas emissions for statutory reporting purposes by government, and for evaluating the energy potential from anaerobic digestion of pig effluent. This paper has compared PigBal predictions of manure total, volatile, and fixed solids, and nitrogen (N), phosphorus (P) and potassium (K), with manure production data generated in a replicated trial, which involved collecting manure from pigs housed in metabolic pens. Predictions of total, volatile, and fixed solids and K in the excreted manure were relatively good (combined diet R2 ≥ 0.79, modelling efficiency (EF) ≥ 0.70) whereas predictions of N and P, were generally less accurate (combined diet R2 0.56 and 0.66, EF 0.19 and –0.22, respectively). PigBal generally under-predicted lower N values while over-predicting higher values, and generally over-predicted manure P production for all diets. The most likely causes for this less accurate performance were ammonium-N volatilisation losses between manure excretion and sample analysis, and the inability of PigBal to account for higher rates of P uptake by pigs fed diets containing phytase. The outcomes of this research suggest that there is a need for further investigation and model development to enhance PigBal’s capabilities for more accurately assessing nutrient loads. However, PigBal’s satisfactory performance in predicting solids excretion demonstrates that it is suitable for assessing the methane component of greenhouse gas emission and the energy potential from anaerobic digestion of volatile solids in piggery effluent. The apparent overestimation of N and P excretion may result in conservative nutrient application rates to land and the over-prediction of the nitrous oxide component of greenhouse gas emissions.

The impact of nutrition on the performance of broiler breeders in terms of bodyweight profile, egg production, egg size and shell quality, mortality, fertility and hatchability has been well documented. However, studies on the direct effects of breeder nutrition on subsequent chick quality and offspring performance are limited. The present paper reviews the nutritional factors in broiler breeders that may improve chick quality and progeny performance. Recent research has suggested that the feeding of low crude protein and medium to high energy breeder diets in both rearing and laying period will not only have a positive impact on egg production, egg size, breeder fertility, hatchability and embryonic livability, but also on offspring performance. Improvements include better chick quality, higher chick weight, lower mortality, increased immune responses, enhanced litter quality and broiler growth. Breast-meat yield in the progeny can be improved as the energy to protein ratio increases from the rearing phase to the laying phase, indicating that nutrition of pullets can also affect growth and yields. The effects of maternal diet on offspring performance may depend on the sex of the progeny, with male broilers responding more than female broilers to breeders’ dietary protein and energy concentrations. However, little work has been conducted on the effects of individual amino acids in breeder diets on the subsequent generation. There seems to be some benefits with the use of long-chain poly-unsaturated fats in breeder diets on carcass quality of offspring, but these effects appear inconsistent at this stage. There is substantial evidence that confirms the direct effects of vitamin D and E, and trace minerals, especially in organic form, such as selenium, zinc and manganese, on chick quality and progeny performance. In fact, the impact of breeder nutrition on progeny performance in the field is more likely to be greater under conditions of poor breeder-flock uniformity, low vitamin and trace mineral contents or certain types of stress in the broiler house.

The profitability of a sheep enterprise is greatly influenced by the ability of the ewe to produce a lamb annually. This paper examines the between- and within-breed association between the liveweight and fat score of the adult ewe and key fleece, reproduction and milk production traits. The study analysed the performance of 2846 first-cross Merino and Corriedale ewes from the maternal central progeny test (MCPT) over their first three production cycles. Breed (9 sire breeds) and within-breed (91 sires) correlations were calculated from bivariate correlations of adult liveweight and fat score with fleece, reproduction and milk production traits. The mean liveweight and fatness of the breeds were low to moderately negatively correlated with greasy fleece weight (–0.55 and –0.25, respectively) and moderate to strongly positively correlated with fibre diameter (0.88 and 0.41, respectively). However, the within-breed correlations were generally low to negligible. The genetic relationships between ewe fat score and reproductive traits at the breed and within-breed level was generally low to negligible and, in some cases, negative under production conditions where the ewes were well managed and averaged a fat score of 3.5 pre-joining and became too fat across the production cycle. Strong breed correlations between ewe fat score and milk fat concentration (0.88) suggest that selection of fatter sire breeds will lead to increased fat in their progenies’ milk, which was associated with larger lambs. The potential advantages of selecting for more fat to improve the maternal performance of the ewe seem to be limited in enterprises where the production system can easily be adjusted to restrict the influence of temporary and long-term feed deficiencies, as was achieved within the MCPT research flocks.

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.

Economic losses in pig production are highly due to neonatal mortality and poor postnatal growth performances predominantly of low birthweight piglets. To explore underlying mechanisms, we describe in this paper the effects of age and birthweight on body composition and muscle energy stores. Different parameters were assessed in pairs of low birthweight (LBW, n = 32) and normal birthweight (NBW, n = 32) piglets, at Day 0 (n = 16), Day 3 (n = 16), Day 10 (n = 16) and Day 28 (n = 16) of age. In total six piglets (three LBW and three NBW) per age group were killed for chemical total body composition analysis. The M. semimembranosus of 10 additional piglets (five LBW and five NBW) per age group were sampled for the analysis of muscle lipid and glycogen contents. Fore none of the tested parameters differences related to birthweight were observed (P > 0.05). With increasing age, dry matter, fat and protein percentages increased in both LBW and NBW piglets (P < 0.01). Body ash content remained constant during growth (P > 0.05). Muscle glycogen contents decreased with increasing age for both types of piglets (P < 0.05), whereas no age effects could be observed for muscle lipid deposition (P > 0.05). In conclusion, the age of the suckling piglet has a major impact on its body composition and muscle energy stores but its birthweight unexpectedly has no influence.

The practice of offering some whole grain to broiler chickens alongside a balancing concentrate is meeting increasing acceptance in certain regions, including Europe, Canada and Australia. Whole-grain feeding (WGF) regimes provide economic advantages by effectively reducing feed costs but, to varying extents, WGF regimes also generate improvements in energy utilisation and feed conversion efficiency. However, the context in which these improvements are best realised has yet to be defined adequately. The outstanding response to WGF is the development of heavier relative gizzard weights; however, the causative factors and biophysical and biochemical consequences of heavier, and presumably more functional, gizzards have not been properly investigated. It follows that heavier gizzards would enhance the initiation of protein digestion by pepsin and hydrochloric acid and facilitate amylase-induced starch digestion in the small intestine by the prior physical disruption of starch granules. However, it appears that improvements realised by WGF in energy utilisation and feed efficiency cannot be attributed entirely to heavier gizzards. One alternative or additional possibility is that WGF may influence starch digestive dynamics and provide more gradually or slowly digestible starch, which would benefit energy utilisation and feed efficiency. However, if this is the case, the genesis of this provision is not clear, although it may be associated with larger grain particle sizes and/or increased episodes of reverse peristalsis, but not retarded gut passage rates. The present paper reviews the essentially positive impacts of WGF on energy utilisation and feed conversion efficiency and considers the contexts in which these responses may be best realised and the possible mechanisms driving better performance under WGF regimes for chicken-meat production.

Long-term, declining fertility is a reported trend in high-production dairy herds. Nutrition management is identified as a key area where improvement is required. Most published literature relating to nutrition management of dairy cow fertility examines energy and protein status and peri-parturient calcium (Ca) homeostasis availability. This paper examines the current understanding of Ca homeostasis relevant to improving performance in the high-production dairy herd. In particular, this article reviews Ca and vitamin D nutrition during lactation, for achieving health and productivity improvements in subsequent lactations, with specific reference to pasture-based dairy herds. Vitamin D metabolites are essential for increasing the proportion of absorbed Ca when dietary Ca concentration is low or when the requirement for Ca is high. Vitamin D metabolites stimulate the synthesis of the proteins that control active intestinal Ca absorption. This has particular relevance to cows that may not be able to replenish Ca reserves before parturition, which may be a common occurrence in current pasture-based dairy systems. It is possible that due to reductions in Ca reserves, the effectiveness of the cow to liberate sufficient Ca into plasma at parturition will be compromised as she faces subsequent lactations. This has significant implications for the ability of the cow to progress through transition in a healthy state, maintain an optimum energy balance during early lactation and subsequently conceive. Suboptimal nutritional management of Ca status through successive lactations may be shortening the productive life of the high-producing dairy cow.