Ewe Liveweight Research Articles

Studies on the relationship between live weight and body condition score and estimation of standard reference weight of ewes from the Icelandic sheep breed

The aim of the study was to define the mature live weight of Icelandic sheep breed ewes. Data on body condition scores (BCS) and live weight (LW) spanning 22 production years from the Hestur research farm were analyzed to fit the linear relationship LW = a + b x BCS of ewes in different age categories. Ewe live weight continued to increase until 5 years of age. A general estimate of standard reference weight (SRW) of a mature Icelandic ewe is 70.4 ± 3.4 kg, standardized at BCS 3. For mature ewes, approximately 8.5 kg LW is needed to raise BCS by one unit. SRW creates opportunities for studies relating mature weight to other important genetic traits and for analysing the independent effects of SRW, degree of maturity, and BCS on animal performance.

Live Weight and Live Weight Changes and Some Relationships of Certain Reproductive Traits in the Breeding Female Shugor and Dubasi Sub-Types of Sudan Desert Sheep

This study was carried out at the National Sheep Research Station in Elhuda, Sudan to investigate the situation of female sheep conditions while in gestation and to consult some aspects associated to pregnancy parameters and others on live weight were collected, processed and statistically tested in addition to variability consideration. Thus, live weight changes its variability and some relationships for certain reproductive traits in the Shugor and Dubasi subtypes of Sudanese Desert sheep ewes were studied from mating events to the immediate postpartum date. The overall live weight changes during this period resulted in an increase of 22.8 and 27.6% in the live weight of either of these two ewe groups ,respectively, but with an overall greater in live weight variability within the Shugor as contrasted with that within their contemporary Dubasi ewe group (11.33vs 8.27%, CV), having periodic mean value which ranges from 10.70 -13.5% CV and 7.2 – 8.5% CV, respectively, for the Shugor and Dubasi ewe groups. The combined contribution of the foetal lamb weights, foetal placenta fluids weights composed 20.0% for the Shugor and 17.9% for the Dubasi of the breeding (mating) live weight of each while the weight of the lamb at birth and that of the associated placenta had mean values of 11.1 ±0.06% and 1.23 ± 0.06, respectively, of the Shugor pre-partum ewe live weight but the corresponding mean proportional values in the Dubasi group were 9.48 ± 0.49% and 1.20 ±0.08 % .The regression of gestation length, post-partum ewe live weight and lamb birth weight had mean values of + 0.37 , + 0.71 and 0.002 as related to the breeding (mating) ewe live weight of the Shugor whereas the corresponding regression values in the Dubasi ewes were +0.03 ,+ 0.67 and + 0.03. None of these contrasting parameter values was significantly different in the two subtype groups. Similarly, the regression values of the placenta weight on the lamb birth weight were not significantly different, respecttively, - 0.02 and + 0.032 in the Shugor and Dubasi ewe groups. It is concluded that live weights variations in breeding females should be made manageable to their least possible to allow for more solid data, on the female and its offspring, as this is conductive to performance development.

Validation of maternal and terminal sheep breeding objectives using Irish field data.

Genetic evaluations provide producers with a tool to aid in breeding decisions and highlight the increase in performance achievable at the farm level through genetic gain. Despite this, large-scale validation of sheep breeding objectives using field data is lacking in the scientific literature. The objective of the present study was to evaluate the phenotypic differences for a range of economically important traits for animals divergent in genetic merit for the Irish national maternal and terminal sheep breeding objectives. A dataset of 17,356 crossbred ewes and 54,322 progeny differing in their maternal and terminal breeding index recorded in 139 commercial flocks was available. The association of the maternal index of the ewe or terminal index of the ram and a range of phenotypic performance traits, including lambing, lamb performance, ewe performance, and health traits, were undertaken. Ewes excelling on the maternal index had higher litter sizes and produced progeny with greater perinatal lamb survival, heavier live weights from birth to postweaning and reduced days to slaughter (P < 0.05). Ewe maternal index had no quantifiable impact on lambing ease, carcass conformation, or fat, the health status of the ewe or lamb, ewe barren rate, or ewe live weight. Lambs born to rams of superior terminal index produced heavier lambs from preweaning onwards, with a reduced day to slaughter (P < 0.05). Lambing traits, lamb health, and carcass characteristics of the progeny did not differ between sires stratified as low or high on the terminal index (P > 0.05). Results from this study highlight that selecting either ewes or rams of superior maternal or terminal attributes will result in an improvement on pertinent performance traits of the national sheep flock, resulting in greater flock productivity and profitability.

Frequency of feeding during the periconceptional period did not alter reproduction in Merino sheep

Context During drought, it is currently recommended to feed complete rations to sheep every second or third day, rather than daily, to reduce labour costs and the incidence of shy feeders. However, the frequency of feeding to ewes in the periconceptual period may influence fertility and fecundity and therefore profitability. Aims The study was designed to determine whether the feeding frequency of maintenance energy levels during joining affects reproductive performance and wool production of Merino ewes. Methods A group-fed pen study was conducted using two treatments and four replicates. Naturally oestrous-cycling Merino ewes (n = 800) were fed barley grain (90%) and wheat straw (10%) from 17 days before ram introduction until Day 30 of a 48-day joining period, either once-daily or on alternate days at maintenance energy levels. Lambing performance was recorded for 505 ewes pregnant by Day 19 of joining. Wool quality was assessed on Day 117 after commencement of joining. Key results Clinical acidosis occurred in both treatments, although the rate of mortality was low (4/800). The proportion of shy feeders was not affected (P = 0.486) by feeding frequency (n = 77, removed from pens). For the remaining ewes, weight loss was reduced by 1 kg (P = 0.003) when fed daily. Plasma progesterone concentrations post-mating were reduced (P &lt; 0.001) by 18% with alternate-day feeding. Proportions of ewes mated, returning to service, pregnant or bearing multiple fetuses, lamb survival, lamb weights at marking and ram semen morphology were similar (P &gt; 0.05) between feeding groups. Wool fibre diameter, staple strength and yield were similar between treatments. Ewes removed as shy feeders and joined on pasture recorded a 33% lower pregnancy rate but 17% higher rate of multiple fetuses than pen-joined ewes. Conclusions Ewes can be fed complete high-grain maintenance rations at 2-day intervals during joining without a reduction in reproductive traits or wool quality compared with daily feeding. Implications Producers may save labour with longer feeding intervals; however, greater monitoring and management intervention may be needed to maintain ewe liveweight when fed long term. Impacts in flocks without acidosis, on ram fertility when feeding is prolonged pre-joining, and with different diets require study.

Impact of rangeland enclosure and seasonal grazing on protected and unprotected rangelands in Chakwal region, Pakistan

Scrub rangelands support livestock grazing and provide ecosystem services to their inhabitants. The present study was conducted in Chakwal, an important tract of the Pothwar Plateau, which sustains herds of small domestic and nomadic ruminants. Urbanization and uncontrolled grazing practices have reduced rangeland productivity and increased soil erosion and resulted in poor land conditions. This study assessed the influence of two years of rangeland protection on aboveground vegetation biomass and the chemical composition of plants and aimed to determine the influence of seasonal grazing on the live-weight gain of small ewes. Using the line intercept method, vegetation data from protected and unprotected plots in 2015 and 2016 were collected at two sites, Dhulli and Begal. Vegetation cover was assessed from images using VegMeasure. Results showed that protected study sites displayed higher vegetation biomass (834 and 690 kg ha-1) compared to the unprotected study site (477 and 326 kg ha-1) during April and August of both years. In the seasonal grazing trial, the experimental ewes that grazed on protected rangelands showed higher live-weight gain (33–63 g day-1) compared to live weight of ewes (17–21 g day-1) that grazed on unprotected rangelands during the experimental period of 127 days at both sites. The results suggest that the Chakwal rangeland has tremendous potential to improve vegetation productivity but modern livestock management and seasonal grazing practices are needed to improve carrying capacity and livestock productivity.

Effect of Breeding Heavier Romney Ewe Lambs at Seven Months of Age on Lamb Production and Efficiency over Their First Three Breeding Seasons.

Simple SummaryThis experiment examined the impact of breeding heavier ewe lambs on lamb production and the ability of a ewe to produce a high number and heavier lambs (i.e., efficiency) over the first three breeding seasons. Two groups of ewe lambs were bred at seven months of age at an average live weight of either 47.9 ± 0.36 kg (n = 135) or 44.9 ± 0.49 kg (n = 135). Ewe live weight, number of lambs born and weaned, and lamb live weights were recorded, and ewe efficiency was calculated for each ewe. The weight and number of lambs at weaning over the three-year period did not differ between treatments, however, when data were pooled, heavier ewe lambs at breeding had a greater number and lamb weaning weight over the three-year period. Breeding heavier ewe lambs had no effect on ewe efficiency. There was a positive relationship between ewe lamb breeding live weight and their mature weight. These results suggest that breeding heavier ewe lambs increased the total lamb production over the three-year period, however, it had no effect on ewe efficiency. Before final recommendations can be made, ewe lifetime performance and longevity of heavier ewe lambs at breeding are required.This experiment examined the effect of breeding heavier ewe lambs on lamb production and their efficiency over their first three breeding seasons. Two groups of ewe lambs were bred at seven months of age at an average pre-breeding live weight of either 47.9 ± 0.36 kg (heavy; n = 135) or 44.9 ± 0.49 kg (control; n = 135). Ewe live weight, number of lambs born and weaned, and lamb live weight were recorded until 39 months of age, and efficiency was calculated for each ewe. Although the number and lamb weaning weight did not differ between treatments over three years, when data were pooled, heavier ewe lambs at breeding weaned a greater number of lambs over the three-year period. The total lamb weaning weight over the three-year period increased by 2% for each additional kilogram at ewe lamb breeding. Breeding heavier ewe lambs had no effect on efficiency. These results suggest that although breeding heavier ewe lambs had a positive effect on lamb production over the three-year period, it had no effect on efficiency. Before final recommendations can be made, lifetime performance and longevity to five years of age of heavier ewe lambs at breeding are required.

Effects of Increased Growth Rates Prior to the First Breeding as Ewe Lambs and Pregnancy Rank on Mammary Glands of Two-Year-Old Ewes

This study investigated potential carry-over effects of increased growth rates prior to breeding at seven months of age on mammary glands of two-year-old ewes bearing one or two lambs, and examined the association between ewe mammary structures and the growth of their progeny. Ewe live weight and mammary ultrasound measures were recorded at 119 days of pregnancy, 29 days of lactation (L29), and weaning of the progeny (L79) in 64 two-year-old ewes selected from two treatments. The heavy group (n = 32) was preferentially fed prior to their first breeding at seven months of age, achieving an average live weight of 47.9 ± 0.38 kg. The control group (n = 32) weighed an average of 44.9 ± 0.49 kg at breeding. Lambs (n = 74) were weighed at birth, L29 and L79. Udder ultrasound measures did not differ (p &gt; 0.10) between treatments, indicating no carry-over effects of treatments on mammary glands of two-year-old ewes. The association between ultrasound measures and lamb growth seemed to differ depending on lamb birth rank. More research is needed to further investigate these associations and determine whether ultrasonography could be used to identify ewes whose progeny would have greater growth rates based on birth rank.

Breeding heavier ewe lambs at seven months of age did not impact their subsequent two and three-year-old ewe live weight and reproductive performance

ABSTRACT The current study investigated the effects of growing ewe lambs to a heavier live weight at breeding on their subsequent reproductive performance and live weight at two and three years of age, and the growth of their progeny to weaning. Two groups of ewe lambs were bred at seven months of age at an average pre-breeding live weight of either 47.9 ± 0.36 kg (Heavy; n = 135) or 44.9 ± 0.49 kg (Control; n = 135). Breeding performance, fertility, litter size, lambing percentage, ewe wither height, live weight, progeny survival, and live weight were recorded at two and three years of age. None of the variables measured differed between the Heavy and Control ewes at either two or three years of age (P > 0.10). This suggests that farmers can breed their Romney-type ewe lambs at an average live weight of 48 kg without any negative impacts on reproductive performance at two or three years of age nor on their progeny’s live weight or growth to weaning. Although breeding heavier ewe lambs improved reproductive performance during their first year, further investigations are needed to assess their overall lamb production and efficiency over multiple breeding seasons.

The Effect of Herbage Availability, Pregnancy Stage and Rank on the Rate of Liveweight Loss during Fasting in Ewes

Sheep liveweight and liveweight change are vital tools both for commercial and research farm management. However, they can be unreliable when collection procedures are not standardized or when there are varying time delays between sheep removal from grazing and weighing. This study had two stages with different objectives: (1) A liveweight loss study to determine the effect of herbage availability (Low and High) on the rate of liveweight loss of ewes at different pregnancy stages (approximately 100 days of pregnancy: P100 and 130 days: P130) and ranks (single and twin); (2) A follow-up liveweight loss study to develop and validate correction equations for delayed liveweights by applying them to data sets collected under commercial conditions. Results from each stage showed that the rate of liveweight loss varied by herbage availability and stage of pregnancy (p &lt; 0.05) but not pregnancy-rank (p &gt; 0.05). Further, the rate of liveweight loss differed by farm (p &lt; 0.05). Applying liveweight correction equations increased the accuracy of without delay liveweight estimates in P100 ewes by 56% and 45% for single-bearing and twin-bearing ewes, respectively, when offered the Low-level diet. In ewes offered the High-level diet, accuracies of without delay liveweight estimates were increased by 53% and 67% for single-bearing and twin-bearing ewes, respectively. Among P130 ewes, accuracy was increased by 43% and 37% for single-bearing and twin-bearing ewes, respectively, when offered the Low herbage level and by 60% and 50% for single-bearing and twin-bearing ewes, respectively, when offered the High herbage level. In conclusion, a short-term delay of up to 8 hours prior to weighing, which is commonly associated with practical handling operations, significantly reduced the liveweight recorded for individual sheep. Using delayed liveweights on commercial farms and in research can have consequences for management practices and research results; thus, liveweight data should be collected without delay. However, when this is not feasible, delayed ewe liveweights should be corrected and, in the absence of locally devised correction equations, the ones generated in the current study could be applied on farms with similar management conditions and herbage type.

Application of Machine Learning Algorithms to Predict Body Condition Score from Liveweight Records of Mature Romney Ewes

Body condition score (BCS) in sheep (Ovis aries) is a widely used subjective measure of the degree of soft tissue coverage. Body condition score and liveweight are statistically related in ewes; therefore, it was hypothesized that BCS could be accurately predicted from liveweight using machine learning models. Individual ewe liveweight and body condition score data at each stage of the annual cycle (pre-breeding, pregnancy diagnosis, pre-lambing and weaning) at 43 to 54 months of age were used. Nine machine learning (ML) algorithms (ordinal logistic regression, multinomial regression, linear discriminant analysis, classification and regression tree, random forest, k-nearest neighbors, support vector machine, neural networks and gradient boosting decision trees) were applied to predict BCS from a ewe’s current and previous liveweight record. A three class BCS (1.0–2.0, 2.5–3.5, &gt;3.5) scale was used due to high-class imbalance in the five-scale BCS data. The results showed that using ML to predict ewe BCS at 43 to 54 months of age from current and previous liveweight could be achieved with high accuracy (&gt;85%) across all stages of the annual cycle. The gradient boosting decision tree algorithm (XGB) was the most efficient for BCS prediction regardless of season. All models had balanced specificity and sensitivity. The findings suggest that there is potential for predicting ewe BCS from liveweight using classification machine learning algorithms.

Direct and indirect effects of climate and vegetation on sheep production across Patagonian rangelands (Argentina)

Extensive sheep production is an important agricultural industry in the Patagonia region of Argentina, where the most important production metric is the effective lambing rate of the sheep (L%). Climate factors can affect sheep production in two ways: (i) directly on the survival of the lamb, and (ii) indirectly by determining the start of the growing season, aboveground net primary productivity (ANPP) and the availability of forage. The aim of this study was to determine the relationships between climatic variables and vegetation attributes as the major drivers of sheep productivity (ewe live weight pre-mating (ELW) and effective lambing rate (L%)), using structural equation modelling. We observed that precipitation in late autumn/winter and vegetation productivity in late spring/summer were the main drivers and were positively associated with ELW. The ELW was highly and positively correlated with L%. Additionally, the maximum temperature in late spring showed a strong direct and negative relationship with L%. These results indicated that ELW should be taken into account when modelling L%. Regional Patagonian climate change models predict, for the next century a decrease in precipitation and an increase in temperature. Thus, according to our findings, sheep production systems would be affected by a decrease in primary productivity, as well as ELW and L% since these variables are positively associated with precipitation and negatively with temperature. The use of strategic supplementation to meet nutrient requirements and protection from climatic stressors during physiologically demanding production stages of pregnancy and lactation through additional shelter and housing for the sheep could mitigate the effects of climate change by having a positive effect on L% and, therefore, on the total farm income.

ENERGY REQUIREMENTS OF YOUNG EWES FED GUINEA GRASS (PANICUM MAXIMUM) FOR MAINTENANCE AND GAIN

Energy requirement for maintenance and weight gain of non-lactating, non-pregnant West African Dwarf ewes were determined by using equation of the form DOMI = aw0.75 + bG........ (1) where, DOMI = Digestible Organic matter intake (kg/day), W = Liveweight of ewe (kg), G = Liveweight gain of ewe (kg/day), a = DOMI requirement per kg of Wkg0.75, b = DOMI requirement for each kilogram liveweight gain. The regression equation obtained was DOMI = 0.0385Wkg 0.75 + 1.54G........(2). The values of DOM required per kilogram of Wkg0.75 and for each kilogram of liveweight gain, were 0.0385 and 1.54kg respectively. In terms of Metabolizable energy (ME) equation (2) can be written as follows: ME = 523.50Wkg0.75 + 20940.92G........(3) Values of ME required per kilogram of Wkg0.75 and each kilogram of liveweight gain were 523.5 and 20940.92 KJ from equation 3. These results are comparable to those obtained for other breeds of sheep of both temperate and tropical origin.

Экономическая эффективность горного овцеводства в зависимости от живой массы маток

Экономическая эффективность горного овцеводства в зависимости от живой массы маток

Effects of heavier live weight of ewe lambs at mating on fertility, lambing percentage, subsequent live weight and the performance of their progeny

ABSTRACT Ewe lamb live weight at first mating (7 months of age) is positively associated with reproductive performance and led to the recommendation of a minimum mating live weight of 40 kg. This experiment examined the effects of heavier mating live weight of ewe lambs on their live weight, fertility, lambing percentage and their progeny performance to weaning. Ewe lambs (n = 270) were randomly allocated to one of two treatments. The Heavy group (n = 135) was preferentially fed until mating, achieving 47.9 ± 0.36 kg, while the Control group (n = 135) had an average mating live weight of 44.9 ± 0.49 kg. Fertility, lambing percentage, ewe live weights, the survival and live weights of their progeny were recorded. There was a 28% increase in fertility and a 59% increase in lambing percentage in the Heavy group compared to the Control group. Progeny survival and live weights did not differ (P > .05) by treatment. A curvilinear relationship between fertility and ewe live weight at mating was identified, suggesting that ewe lambs should be mated at a live weight of 50–55 kg to maximise fertility and lambing percentage without reducing ewe live weight nor the progeny performance.

Wool and Meat Production of Khangil-type Trans-Baikal Sheep

The wool and meat production of Khangil-type fine-fleece sheep within the Trans-Baikal breed has been studied. It is ascertained that 33.5, 59.1, and 7.4% of sheep are assigned to elite, first class, and second class, respectively, according to the rank structure. Liveweights of fine-fleece rams, replacement rams, ewes, and ewe lambs of the Khangil type exceed the breed standard for liveweight by 28.9, 38.7, 30.0, and 18.9%, respectively, and the breed standard for washed-wool clip by 42.6, 24.0, 22.7, and 38.9%, respectively. Analysis of fine wool quality revealed that rams’ wool corresponds to grade 60, while the wool of ewes, ram lambs, and ewe lambs is grade 64. The wool comfort factor of 86.1% was highest in the rams. It was 6.1, 3.1, and 5.4% higher than that in replacement rams, ewes, and ewe lambs, respectively. Coefficients of correlation between the wool fineness and its crimp and between the fineness and the comfort factor were negative in all the sex and age groups. These coefficients were rather high. A positive correlation of mean intensity (r = 0.274–0.652) between the wool fineness and the comfort factor was revealed. The results of slaughtering the fine-fleece ram lambs at the age of 6 months for control purposes indicated their high meat production performance. Thus, slaughter weight, slaughter yield, meat at grade 1, and coefficient of meatiness comprised 16.7 kg, 46.3%, 91.0%, and 3.4, respectively.

The effect of reproductive loss on the performance of a research flock.

The reproductive performance of a sheep flock is dependent on a multitude of complex interacting factors. Achieving optimal flock performance requires knowledge of the reproductive steps and how these are linked and related to available measurements of the state and performance of the flock. The goal was to use previously collected data from a research flock that had undergone selection for fecundity (11,369 lambing records), to model the key reproductive steps affecting flock reproductive performance. The model was used to investigate how changes in liveweight, age, ovulation rate, number of fetuses at midpregnancy, number of lambs born, and birthweight affect the number of lambs weaned and the weaning weight of each lamb in this flock. The data available from the research flock were used to parameterize models of each reproductive step and assess the role of ewe age and premating liveweight on each reproductive step. These models were then linked together as a simulation tool to assess the role of different parameters on flock reproductive performance, which was defined as the total weight of lambs weaned per ewe exposed to the ram. Flock elasticities were calculated that characterize the relative importance of the effect of average premating ewe liveweight (0.81), average ovulation rate (0.33), variance in ovulation rate (-0.095), embryo survival (0.72), lamb survival (1.03), conception failure (0.35), and average ewe age (0.056) on the total kilograms of lamb liveweight at weaning per ewe exposed to the ram. The largest elasticity for lamb survival indicated that a 1% increase in lamb survival is expected to have a 1.03% increase in the total kilograms of lamb liveweight at weaning per ewe exposed to the ram in this flock. Assuming similar costs, interventions to increase lamb survival for this flock will provide the largest increase in the total kilograms of lamb liveweight at weaning per ewe exposed to the ram, which is a key metric of flock performance.

The performance and profitability of plantain/clover pasture mixtures in East Coast farming systems

Yield and animal performance data from plantain/clover and resident ryegrass-based pastures were collected over several years from six properties on the East Coast of the North Island. This information was used in a FARMAX® model developed for a hypothetical farm based on data collected by the Beef + Lamb Economic Service. The hypothetical farm was 495 ha with 50 ha of flats used for silage and/or winter forage crop. The base model had a gross margin of $703/ha. The 50-ha flat block was modelled as if in a plantain rotation with two thirds in plantain and one third in annual ryegrass each year. The higher yields and better-quality feed on the plantain block improved animal performance and carcass weights. Early mating of one-year ewes for feeding on plantain provided a very high-returning enterprise. More ewes and lambs were killed early at heavier carcass weights with a premium before the onset of summer-dry conditions. This became a force multiplier across the entire farm as more feed was available for other stock and lamb carcass weights increased across the farm. Highest returns were generated by using the extra quality feed to increase ewe liveweights by 8 kg. Whilst ewe numbers had to be decreased, this was more than compensated for by the higher lambing percentage and greater number of lambs from mated hoggets. The combined effect was an increase in farm gross margin by around $200/ha and in farm returns of $100,000.

Production responses and cost-benefit of long-acting pre-lambing anthelmintic treatment of yearling ewes in two commercial flocks in New Zealand

AIMS: To investigate the production responses and cost-benefit of administering a controlled-release anthelmintic capsule (CRC) to pregnant yearling ewes prior to lambing.METHODS: Yearling ewes from two commercial sheep flocks (A, n=489; B, n=248) in the North Island of New Zealand were enrolled in the study. Prior to lambing, CRC containing albendazole and abamectin were administered to half the ewes while the other half remained untreated. Ewe liveweights and body condition scores were measured prior to lambing, at weaning and, for Flock B, prior to subsequent mating. Lambs were matched to dams shortly after birth and the weight and number of lamb weaned per ewe were determined. A cost-benefit analysis was undertaken for Flock B considering the increased weight of lamb weaned per ewe, and the weight of ewes at the next mating and the benefit in terms of lambs born.RESULTS: The mean weight at weaning of treated ewes was greater for treated than untreated ewes by 2.76 (95% CI 0.64–4.88) kg in Flock A (p<0.001) and 2.35 (95% CI −0.41–5.12) kg in Flock B (p=0.003); the weight of lamb weaned per ewe was greater for treated than untreated ewes by 1.43 (95% CI −0.71 to –3.49) kg in Flock A (p=0.041) and 3.97 (95% CI 1.59–6.37) kg in Flock B (p<0.001), and ewe liveweight prior to subsequent mating was greater for treated than untreated ewes in Flock B by 4.60 (95% CI 3.6–5.6) kg (p<0.001). There was no difference in the percentage of lambs reared to weaning between treated and untreated ewes in either flock (p>0.8). The overall cost-benefit of treatment for Flock B was NZ$9.44 per treated ewe.CONCLUSIONS AND CLINICAL RELEVANCE: Pre-lambing CRC administration to yearling ewes resulted in increased ewe weaning weights and weight of lamb weaned in both the flocks studied. There was an economic benefit in the one flock where this was assessed.

Grazing multispecies swards improves ewe and lamb performance

A two-year (2015 and 2016) grazing study was established to compare ewe and lamb performance when grazed on a perennial ryegrass only sward compared to more diverse sward types. In that study four sward types were investigated: a perennial ryegrass (Lolium perenne) only sward receiving 163 kg nitrogen per hectare per year (N/ha/yr) (PRG); a perennial ryegrass and white clover (Trifolium repens) sward receiving 90 kg N/ha/yr (PRGWC); a six species sward (two grasses (perennial ryegrass and timothy (Phleum pratense)), two legumes (white and red clover (Trifolium pratense)) and two herbs (ribwort plantain (Plantago lanceolata) and chicory (Cichorium intybus)) receiving 90 kg N/ha/yr (6S); and a nine species sward containing cocksfoot (Dactylis glomerata), greater birdsfoot trefoil (Lotus pedunculatus) and yarrow (Achillea millefolium) in addition to the six species listed above, receiving 90 kg N/ha/yr (9S). Each sward type was managed as a separate farmlet and stocked with 30 twin-rearing ewes at a stocking rate of 12.5 ewes/ha under rotational grazing management from turnout post-lambing until housing. Lamb live weight was recorded fortnightly and lambs were drafted for slaughter at 45 kg. Ewe live weight and body condition score (BCS) were recorded on five occasions annually. Lamb faecal egg count (FEC) was recorded fortnightly and lambs were treated with anthelmintics when mean lamb FEC per sward type was above 400 eggs per gram. Ewes grazing the 6S and 9S swards had heavier (P < 0.01) live weights and BCS throughout the study than the ewes grazing the PRG sward. Lambs grazing the 6S sward were heavier than lambs grazing all other sward types of 14 weeks old (P < 0.05). Lambs grazing the PRG sward required more days to reach slaughter weight than lambs grazing all other sward types (P < 0.001). Lambs grazing the 6S and 9S swards required fewer anthelmintic treatments than lambs grazing the PRG or PRGWC swards. In conclusion, grazing multispecies swards improved ewe and lamb performance and reduced the requirement for chemical anthelmintics.

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 &amp;lt; 0.001). There was also an improvement in survival of multiple born lambs with increasing CS at lambing (P &amp;lt; 0.001). Birthweight was significantly related to survival (P &amp;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.