Ewe Liveweight Change Research Articles

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

Nematode parasites are not a major cause of illthrift in adult ewes in New Zealand

ABSTRACTIllthrift, defined as low body condition score (BCS), is a problem in adult ewes on many farms in New Zealand, and nematode parasites are often considered a significant contributing factor. Here we test the hypothesis that, over the lambing-lactation period, parasites are a significant causal factor in ewe illthrift, and that anthelmintic administration to low BCS ewes results in a greater improvement in condition than treatment of other ewes. Faecal nematode egg count (FEC) prior to lambing and ewe liveweight change over the study period were poorly correlated, and both were independent of pre-lambing BCS, as was ewe response to anthelmintic treatment. Some ewes lost, or gained, considerable amounts of weight independent of their BCS, the number and size of lambs reared, and anthelmintic treatment. We find no evidence that ewes of low BCS have higher FECs, or a larger response to anthelmintic treatment than ewes in better condition.

Effect of parity and type of lambing on performance and udder traits of Bandirma ewes

The objective of this study was to evaluate the effect of parity and lambing type on body condition score (BCS), live weight of ewes (LWE), daily milk yield (DMY), lambs growth performance and udder measurement of ewes during first 3 months of lactation in Bandirma ewes. Bandirma ewes (78) with healthy udders and their lambs (117 heads) were used. BCS of ewes was affected significantly by lambing types at first and third months of lactation, while lambing types were not significant in second month of lactation. Parity of ewes did not significantly affected BCS except third month of lactation which was significantly affected by parity. Effects of lambing types and parity of ewes were significant on BCS at first and third month of lactation. Live weight change of ewes was affected significantly by parity, while lambing types were not significant at first 3 months of lactation. There was a significant effect of parity on average daily milk yield at early lactation stage. Also lambing type had significant effect on DMY at first 2 months of lactation. DMY at third month of lactation were not affected by lambing types. Parity affected lambs growth performance in the first three months of lactation. No significant differences between lambing type and parity of ewes in udder measurement, except udder circumference (UC) measure which was significantly affected by parity and lambing types. The effects of parity of ewes were significant on udder circumference and udder width while the other udder traits were not significant. The effects of birth type of ewes were significant on udder width while the other udder traits were not significant. The positive and significant correlations were observed between udder circumference and udder width and daily milk yield in Bandirma sheep. Significant positive phenotypic correlations were determined between lambs live weight (LLW) and LWE, BCS and DMY, LLW and LWE, DMY and LWE. The results suggested that early stage of lactation of ewe’s can be feed supplemented with high energy or high protein for increasing milk production. The control of these physiological stages of ewe may be improved BSC and DMY, also growth performance of lambs. Hence, we recommend that early stage of lactation performance and udder measurements of ewes are to be taken into consideration for selection programme of Bandirma sheep.

Effect of supplementary feeding to ewes and suckling lambs on ewe and lamb live weights while grazing wheat stubble

A trial was conducted to determine the effects on the performance of creep feeding suckling lambs and supplementing ewes that were grazing wheat stubble. Eight experimental units of South African Mutton Merino (SAMM) ewes and lambs were used in a 2 (supplementing ewes or not) x 2 (creep feeding lambs or not) factorial design. Two groups, consisting of 68 and 100 ewes, grazed 12.9 ha and 18 ha paddocks, respectively. Each group was then divided into four sub-groups, of which two sub-groups received supplementation and two were not supplemented. Within each ewe group, two groups of lambs received creep feeding and two groups did not. Ewe groups were rotated between these camps each week to eliminate the effect of camps. Supplementation at 200 g/day took place from February 2000 to May 2000, after which it was increased to 300 g/day until August 2000. The liveweight change (LWC) of ewes during the total experimental period from 22 November to 31 August, as well as during the feeding period from 22 February to 31 August, was not affected significantly by supplementation, although ewes that received supplementary feed maintained higher live weights for a large part of the experimental period. The average daily gain (ADG) of lambs from ewes that received supplementary feed tended (9%) to be higher compared to the lambs of ewes that did not received any supplementary feed. There was no significant difference in the LWC of ewes during the total experimental period or during the feeding period due to the creep feeding of their lambs. The ADG of the lambs that received creep feeding from 24 May to 28 August was 25% higher than that of lambs that did not receive it, and the creep-fed lambs maintained higher live weights for most of the experimental period. Keywords : Creep feeding, SA Mutton Merino ewes, supplementation, wheat stubble

Increasing weight gain during pregnancy results in similar increases in lamb birthweights and weaning weights in Merino and non-Merino ewes regardless of sire type

Birthweight is the single largest determinant of survival in lambs and can be predicted from ewe liveweight at conception and liveweight changes during pregnancy. These prediction equations are known for Merino ewes, but it is unknown if they are applicable to non-Merino breeds. We tested the hypothesis that increasing conception weights of ewes will increase the birthweights, survival to weaning and weaning weights of their lambs, irrespective of ewe or sire breed, but that non-Merino lamb birthweights would be less responsive than Merino lamb birthweights, to changes in ewe liveweights during pregnancy. Ewe liveweight, lamb birth and weaning weight records from Merino sires mated to Merino ewes (MM), Border Leicester Merino (Maternal) sires mated to Merino ewes, Poll Dorset or Suffolk (Terminal) sires mated to Merino ewes (TM), and Terminal sires mated to Border Leicester Merino ewes (TMAT) were analysed from the 2007 to 2011 lambings of eight information nucleus flocks. Lamb birthweights increased by 0.032 ± 0.0012 kg from MM ewes and 0.024 ± 0.0026 kg from TMAT ewes with every 1-kg increase in conception weight (P < 0.001). Irrespective of breed, for every 1-kg increase in liveweight change during early and late pregnancy, lamb birthweights increased by 0.021 ± 0.0019 kg and 0.034 ± 0.0019 kg and weaning weights by 0.26 ± 0.013 kg and 0.09 ± 0.011 kg, respectively (P < 0.001). Survival to weaning of single, twin and triplet lambs was highest for lambs from TMAT ewes (89.3% ± 1.25, 84.6% ± 1.49 and 73.4% ± 2.35) and lowest for TM ewes (80.2% ± 1.89, 72.8% ± 2.09 and 57.4% ± 2.98; P < 0.001). Coefficients relating ewe liveweight change during pregnancy to lamb birthweights are similar for Merino and Maternal ewes, however conception weights of Maternal ewes are significantly heavier than Merino ewes when run together, and lamb birthweights from Maternal ewes are less responsive to ewe conception weights. The coefficients reported in this paper will enable development of optimum management guidelines for single-, twin- and triple-bearing Maternal ewes.

Mob-based walk-over weights: similar to the average of individual static weights?

Merino ewe liveweight represents an objective measure shown to have a profound effect on production outcomes and therefore research into technology that provides accurate and timely feedback of ewe liveweight change is warranted. Most sheep in Australia are not individually identified and therefore management of sheep is on a flock or ‘mob’ basis. Mob-based walk-over weighing (MBWOW) is a remote weighing concept for sheep flocks whereby animal weights are collected as they pass freely over a strategically placed weighing platform. The weights are then collected by the livestock manager, analysed and interpreted to aid nutritional decision making on a whole-flock basis. The hypothesis tested in this study was that data from MBWOW systems is comparable to data from static weighing sessions. At three sites, MBWOW data was collected simultaneously with monthly static weighing sessions. Raw data from MBWOW from each site was manipulated through a series of methodologies that were compared according to their relationship with the static weight data. All forms of MBWOW data showed a significant relationship with static weighing data (P < 0.05). Using a 25% filter (data within 25% of a predetermined central weight kept) and grouping data into 5-day groups strengthens the relationship between MBWOW data and static weighing data. In 1-day groupings, MBWOW data with a 25% filter and subjectively chosen central weight showed the strongest relationship (R2 = 0.89) with static weighing data. In 5-day groupings, MBWOW data with a 25% filter and reference weight from a previous weighing event as a central weight showed the strongest relationship (R2 = 0.88) to static weighing data. The former MBWOW data manipulation methodology had the least mean numerical difference (±s.d.) between MBWOW data and static weighing data (1.86 ± 0.85 kg), yet the latter had the least mean numerical difference in change-in MBWOW data and change-in static weighing data (1.51 ± 0.39 kg), and as change-in liveweight has the most application to industry, it is recommend as the preferred data manipulation technique. These findings suggest that although MBWOW is not fully congruent with static weighing, a strong relationship (R2 > 0.8) between the two and low mean numerical difference in change-in liveweight indicates that MBWOW has potential to be used to established liveweight profiles for Merino ewes that aid nutritional management.

Improving the nutrition of Merino ewes during pregnancy increases the fleece weight and reduces the fibre diameter of their progeny's wool during their lifetime and these effects can be predicted from the ewe's liveweight profile

Nutrition of ewes during pregnancy can have permanent impacts on the production potential of their progeny. The hypothesis tested in the experiments reported in this paper was that improving the nutrition of Merino ewes during pregnancy and lactation increases the fleece weight and reduces the fibre diameter of their progeny’s wool during their lifetime. In addition, that these effects on the progeny’s wool production can be predicted from the ewe’s liveweight profile. At sites in Victoria and Western Australia in each of 2 years, a wide range in the liveweight and condition score profiles of Merino ewes was generated by varying the amount of supplements fed from joining to Day 100 of pregnancy and the amount of feed on offer grazed from Day 100 to weaning. The site in Victoria was based on perennial pastures and included both single- and twin-bearing ewes whereas the site in Western Australia was based on annual pastures and included single-bearing ewes only. The production and characteristics of wool from the progeny were measured until 51 months of age at the site in Victoria and 33 months of age at the site in Western Australia. The nutritional treatments and the resulting changes in ewe liveweight had significant impacts on the fleece weight and to a lesser extent the fibre diameter of wool produced by their progeny, but there were no consistent effects on other characteristics of progeny fleece wool. The fleece weight of the progeny was related to the liveweight change during pregnancy of their mothers (P < 0.05) and the relationships were similar for the two experiments at each site. At the site in Victoria, a loss of 10 kg in ewe liveweight between joining and Day 100 of pregnancy reduced fleece weight by ~0.2 kg at each shearing until 51 months of age whereas gaining 10 kg from Day 100 of pregnancy to lambing had the opposite effect. The effect of changes in ewe liveweight during late pregnancy on the fleece weight of their progeny at each shearing was of similar magnitude at the site in Western Australia. When evident, the effect of the ewe liveweight profile on the fibre diameter of progeny wool was opposite to the effect on clean fleece weight and the effect of poor nutrition in early to mid pregnancy could be completely overcome by improving nutrition during late pregnancy. Twin-born and reared progeny produced ~0.3 kg less clean wool at each shearing (P < 0.001) that was 0.3-μm broader (P < 0.001) than that from single-born progeny at the site in Victoria. However, the effects of varying ewe nutrition and ewe liveweight change during pregnancy on fleece weight and fibre diameter of progeny wool were similar (P > 0.05) for both single- and twin-born or reared progeny. Overall, these results supported our hypothesis and it is clear that the nutritional management of Merino ewes during pregnancy is important for optimal wool production from their progeny during their lifetime.

The effect of high dietary protein levels during late gestation on colostrum yield and lamb survival rate in singleton-bearing ewes

The study was carried out to determine the effect of crude protein (CP) levels in late pregnancy on the subsequent colostrum production and lamb survival rate. A total of 40 singleton-bearing Hampshire Down X Karayaka (F 1) crossbred ewes were allocated to two treatment groups ( n=20 for each group), namely a control (P) and high CP (1.4P) group. The ewes in the P group were fed a protein maintenance level for pregnant ewes (117 g CP and 10.5 MJ metabolizable energy (ME)/kg dry matter (DM)), while ewes in the 1.4P group were fed 1.4 times the protein requirement level for pregnant ewes (165 g CP and 10.5 MJ ME/kg DM). The high crude protein level (1.4P) offered to the ewes did not affect lamb body weight from birth to weaning, however, it increased the live weight changes of ewes (2.5±1.3 kg for P versus 6.4±1.5 kg for 1.4P; P<0.05), lambing difficulty (5% versus 30%; χ 2=4.33; P<0.05) and lamb birth weight (4.3±0.1 kg versus 4.9±0.1 kg; P<0.05). It also decreased the total colostrum yield (1700±165 g versus 1200±147 g; P<0.01) and lamb survival from birth to weaning (100% versus 80%; χ 2=4.44; P<0.05). These results indicate a high level of CP (1.4P) supplementation to singleton-bearing ewes during late gestation to increase lamb birth weight decrease colostrum yield, increase lambing difficulty and reduce lamb survival rate prior to weaning. In conclusion, because of the adverse effect of high dietary protein nutrition during late gestation on colostrum yield and lamb survival rate in singleton-bearing ewes, feeding of protein to pregnant ewes with a view to increase postnatal lamb growth performance and lamb survival rate, should be treated with caution.

Use of varying combinations of energy and protein sources as supplementary feed for lambing ewes grazing cereal stubble

Summary. Three feeding trials compared production of lambing ewes grazing stubbles and fed different combinations of energy and protein supplements as loose licks. Each experiment had 2 treatments in a 2 x 2 factorial design. Experiment 1 compared urea (12.5 g/ewe. day) with fish meal (100 g/ewe. day) when fed with molasses (100 g/ewe. day) for 38 days during late pregnancy. Fish meal increased liveweight gain (from 2.0 to 5.7 kg) and wool growth (20%) but urea had no effect. In experiment 2, urea (12.5 g/ewe. day) was fed in combination with molasses (200 g/ewe. day) or barley meal (200 g/ewe. day) for 63 days during late pregnancy (last 6 weeks) and early lactation. Ewes supplemented with the barley–urea combination gained 5.6 kg during the last 6 weeks of pregnancy compared with 0.40 kg for barley and the 1.02 and 1.34 kg weight loss for ewes receiving molasses and the molasses–urea combination, respectively. Experiment 3 compared urea (12.5 g/ewe. day) with sweet lupin meal (106 g/ewe. day) when fed with barley meal (200 g/ewe. day) for 56 days during late pregnancy (last 4 weeks) and lactation. Sweet lupin meal improved the liveweight change of ewes during pregnancy (from 160 to 200 g/ewe. day) as well as the birth weight of lambs (400 g) but urea had no effect. The performance of lambing ewes grazing low-quality pasture at a high stocking density (&gt;4.5 ewes/ha) for a long period (&gt;130 days) can be improved by relatively low amounts of supplements such as fish meal, sweet lupin meal and barley–urea.

The effect of nutrition in mid pregnancy and ewe liveweight change on birth weight and management for lamb survival in highly fecund ewes

The effect of moderate undernutrition in mid pregnancy on lamb birth weight and survival of single- and multiple-bearing ewes is reported. A total of 1220 ewes of 3 crossbred types with different fecundity, Booroola Merino x Dorset (BD), Trangie Fertility Merino x Dorset (TD) and Border Leicester x Merino (BLM), were examined over 2 years. The treatments were low (L) and high (H) nutrition at pasture for 4 weeks from about day 75 of pregnancy. Ewe liveweight of the L group at the end of the treatments was 5 kg lower in 1984 and 8 kg lower in 1985 (P&lt;0.01) than the H group. The differences were smaller by late pregnancy and post-lambing. The L treatment increased (P&lt;0.01) birth weight by 0.16 kg in 1984 but had little effect in 1985. Litter size had the greatest effect on birth weight (P&lt;0.01). Ewe crossbred type and lamb sex effects were also significant (P&lt;0.01), although they tended to be reduced for higher order births. Nutritional treatment had no effect on gestation length. Ewe liveweight at joining and weight gains before and after the treatment period significantly affected birth weight and accounted for the large difference in birth weight between years (0.7 kg). Ewe weight gain during the treatment period in mid pregnancy had no significant effect on lamb birth weight. Nutritional treatment in mid pregnancy had no effect on lamb survival. Litter size significantly affected lamb survival, although inclusion of birth weight in the model reduced the effect. Weather conditions, as measured by chill index, significantly (P&lt;0.01) affected lamb survival in 1984 but accounted for less variation in 1985 (P&lt;0.05). Lamb survival for ewes was ranked BLM &gt; TD &gt; BD. Maximum survival was achieved at birth weights of 4-5 kg from BD and TD ewes and 5-6 kg from BLM ewes. The L treatment reduced (P&lt;0.01) ewe greasy fleece weight by 0.15 kg but did not affect staple strength. Plasma glucose concentration at the end of treatment was lower (P&lt;0.01) for L ewes, but there was no difference between L and H ewes in late pregnancy. Glucose declined with increasing fetal number. Plasma B-hydroxybutyrate concentration was lower for the H group than for L, and also for BLM than TD and BD ewes (P&lt;0.01).

Responses to protein plus energy supplements of pregnant ewes eating mature grass diets

Three experiments were conducted with ewes during late gestation (last 4 weeks) to examine metabolic and lamb birth weight responses to supplements. In a metabolism experiment, 18 ewes were divided into 2 groups and offered 800 g chopped Rhodes grass (Chloris gayanu, 1.1% N) with or without a supplement of 150 g cottonseed meal + 50 g molasses, daily until parturition. Supplementation was associated with significant increases in intake of digestible dry matter (37%) and crude protein (121%). Supplemented ewes had significantly greater liveweight gain (173 v. 39 g/day), plasma glucose (2.9 v. 2.5 mmol/L), glucose entry rate (20.6 v. 12.3 mmol/h), udder measurements (e.g. circumference, 548 v. 443 mm), and milk yields (measured at day 2 post-partum, 1748 v. 627 mL/day), and had heavier lambs at birth (3.9 v. 2.9 kg). In a second experiment, 10 ewes were pen-fed chopped Rhodes grass ad libitum, and 5 received individually 150 g cottonseed meal + 100 g molasses administered daily. Supplemented ewes were significantly heavier (47.8 v. 45.0 kg) in the last week before parturition. Supplementation was associated with improved ewe liveweight change (48 v. -33 g/day) and lamb birth weight (3.4 v. 2.4 kg). In a third experiment, 42 ewes grazed a 80-ha paddock during a dry season and received daily 1 of 3 individually administered treatments: control (20 mL water drench); 7 g urea + 4 g sulfate of ammonia in a 20 mL drench; 100 g meat and bone meal + 100 g molasses + 3 g urea administered as a slurry in a single drench. Performance and metabolic parameters for the 3 groups were ewe liveweight gain (38, 80, 131 g/day), rumen ammonia concentration (7.1, 10.0, 8.6 mmol/L), plasma glucose (2.6, 2.6, 2.1 mmol/L), plasma hydroxybutyrate (0.6, 0.5, 0.4 mmol/L), and lamb birth weight (3.5, 3.7, 4.0 kg). Differences were significant between the protein-supplemented and control groups for all parameters except rumen ammonia concentration. The data support the conclusion that protein supplements provide a production response in pregnant ewes that is sufficient to improve lamb survival rates when the nutrition from grass diets is inadequate.

Influence of shearing regime and grass silage quality on the performance of pregnant ewes

ABSTRACTThe performance of housed ewes, shorn at various stages during pregnancy and offered silages ad libitum made from grass harvested at two contrasting stages of growth, was studied. The mean increase in silage dry matter (DM) intake due to shearing (0·11 kg/day; P &gt; 0·05) was small in comparison with that resulting from offered earlier-cut silage (0·27 kg/day; P &lt; 0·001). The mean increase in twin lamb birth weight from ewes shorn at least 6 weeks before lambing was almost 1 kg per lamb (P &lt; 0·01) with no significant effect on ewe live-weight change. Greatest increase in lamb birth weight (1·11 kg; P &lt; 0·01) was produced by shearing several times during pregnancy, with least response (0·23 kg; P &lt; 0·05) from shearing once only, 4 weeks before lambing. The effect of silage quality on lamb birth weight was not significant, despite the large difference in DM intake of the two silages. This difference in intake was reflected by ewe live-weight change over pregnancy with those ewes offered early-cut silage gaining 5·57 kg while those offered late-cut silage lost 4·53 kg (P &lt; 0·001). There was a marked fall in respiration rate and rectal temperature after each shearing and, compared with shorn ewes, unshorn ewes had a mean gestation length which was 2·04 days shorter (P &lt; 0·01). In terms of lamb growth rates, ewe milk yields and milk composition, the performance on all treatments after turn-out to pasture was satisfactory and no significant carry-over effect of treatments applied during pregnancy were observed during the first 5 weeks of lactation.

Sheep productivity in the Ethiopian Highlands on a diet supplemented with urea-molasses block and/or noug cake.

A feeding experiment was carried out in which adult ewes of the Ethiopian Highland Menz breed grazed on meadow pasture were supplemented with urea-molasses block and/or noug cake. There was low consumption of urea-molasses block (67 gd-1) and its contribution to total nitrogen requirement was minimal. Dietary treatment had no significant effect on liveweight changes of ewes, their reproductive performance and performance of the lambs. When there was liver fluke infection, ewes and their lambs which were supplemented with urea-molasses block and/or noug cake had better survival compared to those which did not get any supplements (35% mortality vs 55%). The rumen ammonia-N concentration was significantly lower in the control sheep (11 mg/100 ml) and those that received only urea-molasses (14 mg/100 ml) and highest in sheep receiving the urea-molasses block and noug cake (26 mg/100 ml). The volatile fatty acid proportions were not significantly affected by the diets. Low level of urea-molasses block consumption seemed to be a main factor limiting the usefulness of the urea-molasses block and it is recommended that factors likely to enhance its consumption be investigated.

Low nutrition of ewes in early pregnancy and the residual effect on the offspring

SUMMARYMature Merino ewes (n = 500) were allotted at random to embryo removal (day 35; day 0 = day of oestrus detection), foetal removal (day 90) or lambing groups. These groups were further randomly divided into four single-sire mating groups. From day 1 until day 35 ewes were individually penned and fed either 50 or 150% of a maintenance ration (0·5 M or 1·5 M respectively). At day 35 single embryos were removed from anaesthetized ewes in the embryo removal group and all other ewes were endoscoped to confirm pregnancy. These ewes were then returned to pasture. Plasma samples were taken from all ewes on days 2, 4, 16, 23, 30 and 35 for analysis of glucose concentration. At day 90, ewes allotted to the foetal removal group were anaesthetized and plasma samples were obtained from the ewe's jugular vein and the umbilical arteryand vein. Ewes were then hysterectomized and the foetus was weighed and measured. Functional cotyledons were dissected from the uterus and chorio-allantois and all tissues were weighed. The remaining ewes (lambing group) were supervised at lambing and lambs were identified, weighed and measured.Live-weight changes from weaning and wool production and quality were measured in ewe and ram lambs at their first shearing (11 months of age). Ovulation rates in the first two oestrous seasons of the ewes and wool production at their second shearing (2 years of age) were also measured.During the 35-day treatment period, mean live-weight changes of ewes were –4·9 and + 1·8 kg in the 0·5 M and 1·5 M groups respectively. Pregnancy rates were similar in both groups but embryos from 0·5 M ewes weighed less than those from 1·5 M ewes (1·7 ± 0·04 ν. 1·9 ± 0·05 g; P &lt; 0·005). Foetuses taken at 90 days from 0·5 M ewes were smaller than those from 1·5 M ewes but these differences reached significance (P &lt; 0·025) only in the measurement of chin–crown length (8·0 ± 0·09 ν. 7·6 ± 0·11 cm). Correlations between foetal weight and total cotyledon weight, chorio-allantoic weight and empty uterine weight were all significant. Plasma glucose concentrations of ewes in the 0·5 M group were significantly (P &lt; 0·001) reduced by day 9. Differences between the two nutrition groups in maternal and umbilical plasma glucose concentrations at day 90 were not significant, though foetuses from 0·5 M and 1·5 M ewes removed a mean of 30 and 11% respectively of available glucose from the umbilical vein. Differences in live weight between 1·5 M and 0·5 M animals at weaning and in the post-weaning period were not significant (P &gt; 0·05). Wool production and woolquality were similar for both groups. Spontaneous ovulation rates measured on four occasions during the postpubertal oestrous season and on three occasions the following year were not significant (P &gt; 0·05). Treatment with pregnant mare's serum gonadotrophin (PMSG) increased ovulation rates in the ewes of both groups; however, the differences failed to reach significance (P &gt; 0·05); mean (± S.e.) ovulations per ewe were 4·8 ± 0·61 ν. 4·6 ± 0·60 for 1·5 M and 0·5 M group ewes respectively.

The performance of lactating ewes offered diets containing different proportions of fresh perennial ryegrass and white clover

ABSTRACTSix ewes with twin lambs were allocated to each of six restricted feeding treatments with 10, 0·8, 0·6, 0·4, 0·2 or 0 of the diet as perennial ryegrass and the remainder as white clover, and to two treatments with either perennial ryegrass or white clover offered alone ad libitum. Fresh herbage was offered and measurements were made over 8 weeks, with the exception of the ad libitum clover treatment which was terminated after 5 weeks. All lambs were allowed access to clover from 14 days of age. Digestibilities of the herbages were measured during four periods in the experiment.Increasing the proportion of clover in the diet significantly increased the intake of nitrogen by the ewes and the growth rate of their lambs, but had no effect on the live-weight changes of ewes on the restricted treatments. When there was no restriction of intake, ewes ate slightly more clover than ryegrass and lost less weight, but mean daily live-weight gains of their lambs over the first 5 weeks did not differ significantly (0·30 and 0·34 kg for ryegrass and clover, respectively).When ryegrass and clover were eaten alone or together their organic matter digestibilities (OMD) did not change, although OMD declined with increasing level of intake.Initial body condition of the ewes had a significant effect on the decline of ewe live weight and body condition during lactation, and on lamb live-weight gain

Performance of ewes and lambs on perennial ryegrass, cocksfoot, tall fescue and timothy pastures under upland conditions

SUMMARYThe performance of Welsh Mountain ewes and their single Clun-cross lambs on swards of perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.) and timothy (Phleum pratense L.) was studied over 3 years (1975–1977) at a site 305 m O.D. in mid-Wales. Under a rotational grazing regime at a fixed stocking rate of 25 ewes and lambs/ha, mean daily lamb live-weight gain over the 84 days experimental period from early May to late July was 24 g higher on timothy than on perennial ryegrass and tall fescue and 35 g higher than on cocksfoot. Averaged for the 3 years the mean daily lamb live-weight gains were 194, 170, 170 and 159 g on timothy, perennial ryegrass, tall fescue and cocksfoot respectively. There were, however, marked interactions with years.Ewe live-weight change varied considerably between grasses and years with cocksfoot poorer than timothy and perennial ryegrass. Mean ewe live-weight change ranged from an overall loss of 39 g/day in 1975 to a gain of 34 g/day in 1977.Differences detected in animal performance between the four grass species altered during the 84 days of the experiment. Timothy and to a lesser extent tall fescue produced better animal performance early in the season whereas perennial ryegrass came into prominence during July.The results are discussed in relation to the present and potential use of the grass species under upland conditions.

The effect of herbage allowance on herbage intake and performance of ewes and their twin lambs grazing perennial ryegrass

SUMMARYThe effect of herbage allowance on the intake and performance of Scottish Half bred ewes with twin lambs was investigated over the first 16 weeks of lactation. Herbage allowances were defined as g herbage D.M./kg live weight (LW)/day, and were maintained by provision of fresh areas of ungrazed sward each day.Herbage allowances in the range 25–120 g D.M./kg LW/day were offered on an area of perennial ryegrass (Lolium perenne cv. S. 23). Parturition was synchronized and ewes and lambs were turned out to pasture 1 day after lambing.Measurements were made of the herbage intake, live-weight change and milk yield of ewes, of lamb growth rates and of the herbage intake of lambs from 10 weeks of age.Herbage allowance had a significant linear effect on intakes of grass by ewes and lambs. The highest intakes by the ewes were achieved during the second week, and were in the range 23–43 g OM/kg LW/day. Intakes declined, as lactation proceeded, to 19–29 g OM/kg LW/day at week 12. Intakes of lambs were similar in weeks 10 and 12 and were in the range 17–24 g OM/kg LW/day. Allowance had a significant effect on live-weight change of the ewes after the first month and upon final body condition.There was no effect of allowance on milk yield until week 6. Mean milk yields were 2·3 kg/day at day 14, 1·0–1·5 kg/day at day 42 and 0·7–1·1 kg/day at day 84. There was a positive effect of allowance on growth rates of the lambs after the first month. Mean overall growth rates to 84 days of age were 175–243 g/day.

Effects of varying phosphorus intake and requirement on measures of skeletal mineralization in the ewe

Merino ewes were fed a specifically phosphorus-deficient ration, with or without supplementary phosphorus, for 20 weeks, spanning approximately the last 5 weeks of gestation and a 15-week lactation. Non-lactating ewes were employed as controls. No significant differences occurred between groups in liveweight change of ewes or lambs, nor did the groups differ in the mean interval from weaning to first oestrus. Biopsy samples of rib bone taken at the beginning and end of treatment showed significant loss of bone mineral by the end of lactation; ewes suckling twins lost 42 per cent of bone phosphorus, and those with single lambs, 17 per cent. Feeding supplementary phosphorus prevented the significant loss of bone mineral. Fortnightly measurement of the bone density of the hock by radiation absorption also showed differences dependent upon the number of lambs suckled, but failed to detect any effect of phosphorus supplementation. The detection of significant skeletal changes in the absence of effects on production demonstrates the sensitivity of these measures as indices of variations in phosphorus storage. The greater sensitivity of observations on rib bone is probably a reflection of differences between bones in the degree of lability of mineral.

Whole wheat grain feeding of pregnant and lactating ewes and their lambs. 1. The influence of energy, sodium chloride and elemental sulphur on ewe productivity

This experiment was designed to explore the influence of energy, sodium chloride and elemental sulphur on the productivity of pregnant and lactating ewes fed whole wheat grain diets. A central composite design was used to study the response over five levels of each factor. During the last 42 days of pregnancy, the energy treatments resulted in either maintenance of maternal body weights at about 42 kg, or losses of up to 5.5 kg. Ewe maintenance requirements were about 0.14 MJ ME kg-1 day -1 and their foetal requirement was 1 .I 5 MJ ME kg-1 day-1. Sodium chloride and elemental sulphur supplements had no influence on ewe liveweight change up to lambing, but wool growth increased with sulphur supplements of up to about 0.25 to 0.30 per cent. Energy intake and sodium chloride supplementation increased lamb birth weight. After lambing, ewes that had been offered low energy diets increased their liveweight gain and wheat intake with sulphur supplements whereas these supplements reduced the liveweight gain and wheat intake of ewes offered higher energy. Milk production measured on day 14 of lactation averaged 11 53 g day -1 and was not significantly influenced by treatment. These results are discussed in relation to the metabolism of pregnant and lactating ewes, and in the context of the composite design used.

Some effects of live weight and body condition on the milk production of Blackface ewes

SUMMARYApproximately 15 weeks before parturition, forty-eight pregnant Blackface ewes were divided into three similar groups. During the 15–6 weeks prepartum period the ewes were fed to increase the live weights and body condition scores of ewes in each of groups A and B and to decrease those of ewes in group C. At 6 weeks prepartum mean differences of approximately 11 kg live weight and two grades of body condition had been created. Food was rationed to the ewes in all groups per kg live weight based on their weights 6 weeks prepartum, to provide the theoretical requirements of Blackface ewes bearing twin lambs. All groups of ewes made similar live-weight gains in late pregnancy and the mean birth weights of the lambs were also similar. Blood plasma F.F.A. values confirmed that the ewes were similarly nourished in late pregnancy regardless of live weight or body condition. During lactation the ewes were fed 9·2 g D.O.M./kg based on their immediate post-partum live weights, plus an allowance for a predicted level of milk production. Ewes in groups A and C were fed 0·5 and ewes in group B, 0·25 g D.O.M. per g of predicted milk production. The ration was increased after the 1st and 2nd weeks of lactation, then maintained at a constant level for the remainder of lactation. Milk production of the ewes was measured using a lamb suckling technique during a 10-week lactation. The mean daily milk production of ewes in groups A and C were similar and the yield of each of these groups was substantially greater than that of group B ewes. The mean total milk production of ewes suckling twin lambs in groups A, B and C was 127, 108 and 142 kg respectively, and of ewes suckling single lambs 104, 81 and 91 kg respectively. The mean live-weight changes of ewes in groups A and C were similar during lactation. Except for group A ewes suckling single lambs, which maintained their mean live weight, all ewes lost weight in early lactation and consistent gains were not made until late lactation. Greatest live-weight loss occurred in group B ewes and extended further into lactation. Changes in body condition followed a similar course to live weight changes. The mean daily live-weight gain of twin lambs in groups A, B and C was 279, 275 and 284 g respectively, and of single lambs, 318, 300 and 319 g respectively. The evidence indicates that ewes in lean body condition have a higher efficiency of food conversion to milk and that in situations of continuous undernourishment a high state of body condition is undesirable during lactation.