Texel Ewes Research Articles

Changes in the aerobic vaginal flora after treatment with different intravaginal devices in ewes

The objective of this study was to characterize the vaginal bacterial flora and subsequent pregnancy rates after AI in sheep subjected to 4 different estrous synchronization regimes – the use of two intravaginal devices (silicone or polyurethane sponges), and two different treatment periods (7 or 14 days). Twenty-one multiparous Texel ewes were randomly allocated to 4 treatment groups during the breeding season. In the ewes from Group I ( n = 6) and Group II ( n = 5), a polyurethane sponge containing 60 mg MAP was inserted in the vagina for a period of 7 or 14 days, respectively. In the ewes of Group III ( n = 5) and Group IV ( n = 5), an intravaginal progesterone releasing insert (IVP4) containing 160 mg of progesterone in an inert silicone device, was inserted for 7 or 14 days, respectively. At device withdrawal, each ewe was treated with 200 IU eCG i.m. Standard bacteriological procedures were performed on vaginal mucus samples obtained before the introduction of the devices, at device withdrawal and on the day of AI in all groups. Estrus was recorded with the aid of vasectomized rams every 12 h, and AI was performed 52–54 h after device withdrawal, using fresh semen. The intervals between device withdrawal and estrus were: Group I: 56.4 ± 21.5 h; Group II: 42.0 ± 33.9 h; Group III: 51.6 ± 21.5 h; Group IV: 37.2 ± 10.7 h, while the pregnancy rates were: Group I: 83.3%; Group II: 60.0%; Group III: 60.0%; Group IV: 60.0%. The pregnancy rates and the interval between device withdrawal and the occurrence of estrus did not differ between treatments. The predominant bacterial flora population at device insertion was mostly gram positive (G+) (90%) bacteria. The strains most frequently found were Bacilllus sp., Staphylococcus sp. and Corynebacterium sp. Of the 19 isolates made at device removal, 79% were gram negative, with the Escherichia sp. being the most frequently isolated. At the time of AI and regardless of the device used, the 14-day treatment group presented an initial gram positive bacterial flora, while the 7-day groups presented gram negative flora (82%). It could be concluded that the use of intravaginal devices, regardless of their composition (silicone or polyurethane), may generate changes in the normal vaginal bacterial flora of the vaginal mucus. These changes did not reflect on the subsequent fertility. The use of intravaginal devices should however include the adoption of strict hygiene procedures, to minimize the growth of bacterial flora.

Characterisation of white line degeneration in sheep and evidence for genetic influences on its occurrence

Shelly hoof in sheep occurs when the hoof wall becomes detached from the laminar corium; it often then becomes impacted with debris leading to infection, pain and lameness. The problem of shelly hoof is under-reported and is often confused with classical footrot. A study was conducted using data on 9,169 Blackface and Texel sheep from 22 farms in the UK. The aim of the study was to estimate the prevalence of shelly hoof in these breeds, to quantify the genetic basis to shelly hoof, and to describe a pilot trail to characterise the physical properties of horn using Transmission Electron Microscopy (TEM). The results showed that shelly hoof has a high prevalence (47% for Blackface and 24% for Texel ewes) and is under moderate genetic control (h(2) = 0.3). The TEM images showed fragmented dorsal wall horn, microscopic crevices leading deeper into the hoof accompanied by bacteria and other micro-organisms. The invasion of bacteria was facilitated by separation of the cells in a characteristic 'un-zipping' phenomenon, poor attachment of the keratin to the cell membranes, poor cell membrane quality with a 'lace-chain' effect and incomplete keratinisation of the cells.

Ovelhas esquiladas e não esquiladas durante a gestação no Sul do Brasil: efeito na condição corporal e no peso ao nascer dos cordeiros

No presente trabalho, foi testado o efeito da esquila pré-parto na condição corporal (BCS), no peso de cordeiros ao nascer e no seu desenvolvimento. O grupo experimental foi constituído de 64 ovelhas com 3 anos, cruzas Border Leicester x Texel (49-54 kg), encarneiradas em março, foram divididas, aos 74 dias de gestação, em dois grupos de 32 cada. As ovelhas foram mantidas em campo nativo, 5 ovelhas/ha, com disponibilidade aproximada de 800 kg/ha. Aos 74 dias de gestação, um grupo foi esquilado (S) e o outro foi mantido não esquilado (US). A BCS dos dois grupos foi avaliada no início do experimento (P74), P108 e P135 dias de gestação e aos 15 e 24 dias da lactação. Foi também coletado o peso dos cordeiros ao nascer e a duas e três semanas da lactação. Observou-se uma redução na BCS média das ovelhas, de ambos os grupos, durante a gestação e lactação. O grupo S experimentou uma redução significativamente mais severa (P < 0,05) na BCS. A BCS média desse grupo decresceu de 3,3 no dia P74 para 1,79 e 1,22 nos dias P135 e L24. No mesmo período, os valores da BCS média do grupo US foram de 3,11, 2,19 e 1,21. Ao nascer, o peso dos cordeiros, de ovelhas S foi 0,71 kg maior (P < 0,05) do que o dos cordeiros de ovelhas do grupo US. Não houve diferença entre o ganho de peso dos cordeiros dos dois grupos medido a duas e três semanas de vida. O aumento no peso ao nascer dos cordeiros produzido pela esquila das ovelhas durante a gestação, descrito nesse trabalho, poderá reduzir a mortalidade perinatal de cordeiros, especialmente em anos com escassez de pastagem que pode resultar em uma BCS crítica durante a gestação. Os resultados sugerem também que atenção especial deverá ser dada a BCS das ovelhas durante a gestação, prática que não é comum no Sul do Brasil.

Fertility Rates of Ewes Treated with Medroxyprogesterone and Injected with Equine Chorionic Gonadotropin plus Human Chorionic Gonadotropin in Anoestrous Season

The aim of the present paper was to investigate the efficiency of the equine chorionic gonadotropin (eCG) plus human chorionic gonadotropin (hCG) associated with medroxyprogesterone acetate (MAP) to estrous ewes synchronization. Ninety Texel ewes were investigated during seasonal anoestrous. The ewes received intravaginal sponges containing MAP (60 mg) for nine days. At the time of sponges' withdrawal, the ewes were divided into three groups (G): (1) receiving 2 mL of saline i.m. (n = 30), (2) receiving eCG 400 IU i.m. (n = 30), and (3) receiving eCG 400 IU plus hCG 200 IU i.m. (n = 30). Twelve h after sponges' removal, teaser rams were used to estrus check and remained with the ewes for 96 h. The artificial insemination was made with fresh semen 10 h after estrus detection. The effect of the treatment was not significant for the estrous rates among the groups: 73%, 90%, and 86%, respectively. The main effect was observed in the pregnancy and lambing rates among the groups: 70%, 86%, 56%, and 80%, 120%, 56%, respectively. Based on these results from our study, the use of the MAP—eCG is the best choice to improve the fertility rate on ewes.

Características de carcaça de ovelhas de descarte das raças Ideal e Texel terminadas em dois sistemas de alimentação

Avaliaram-se as características de carcaça de ovelhas de descarte das raças Ideal e Texel terminadas em dois sistemas de alimentação. Utilizaram-se 20 ovelhas (10 da raça Ideal e 10 da raça Texel) aleatoriamente distribuídas de acordo com o grupo genético em dois manejos alimentares (confinamento e pastagem cultivada). Os abates foram realizados quando os animais atingiram 3,5 pontos de condição corporal. Os pesos de carcaça quente (PCQ) e de carcaça fria (PCF) e os rendimentos de carcaça quente (RCQ) e de carcaça fria (RCF) das ovelhas Texel foram maiores que os das ovelhas Ideal: 27,85 e 19,04 kg; 27,08 e 18,43 kg; 47,25 e 45,20% e 45,95 e 43,72%, respectivamente. O peso dos cortes perna, paleta, pescoço e costela e os pesos de músculos, ossos e gordura da perna dos animais da raça Texel foram superiores aos obtidos na raça Ideal. Quando avaliadas em porcentagem do peso corporal, no entanto, essas características não diferiram entre as duas raças. O manejo alimentar não influenciou as características de carcaça de ovelhas de descarte. Ovelhas Texel apresentam cortes maiores que os de ovelhas Ideal.

Comportamento ingestivo de ovelhas em lactação alimentadas com dietas contendo diferentes níveis de fibra em detergente neutro

O objetivo do trabalho foi avaliar o efeito do fornecimento de dietas com diferentes níveis de fibra em detergente neutro (FDN) sobre o comportamento ingestivo de ovelhas em lactação. Foram utilizadas 18 ovelhas 5/8 Ile de France 3/8 Texel, confinadas 24 horas após o parto em baias individuais, sendo aleatoriamente distribuídas em três tratamentos: 34, 43 e 52% de FDN na dieta. As dietas, isoproteicas, foram compostas por silagem de milho (Zea mays L.), milho triturado, farelo de soja (Glycine max L.), calcário calcítico, fosfato bicálcico e sal comum, sendo fornecidas ad libitum, duas vezes ao dia, em horários pré-estabelecidos às 8h30min e 16h30min. O comportamento ingestivo dos animais foi determinado mediante apreciação visual. O aumento do nível de FDN na dieta influenciou significativamente os consumos de MS e FDN, a produção de leite e os tempos despendidos em ingestão, ruminação, ócio e mastigação total, que variaram de forma quadrática (P<0,05). As eficiências de ingestão e ruminação de FDN, expressas em g h-1, aumentaram (P<0,05), ao passo que as eficiências de ingestão e ruminação de MS decresceram linearmente (P<0,05) com o incremento do nível de FDN da dieta, sendo necessário maior período de tempo para ingerir e ruminar uma mesma quantidade de alimento. Altos níveis de FDN na dieta podem acarretar depressão do consumo de matéria seca.

Hormonal relationships during the periovulatory period among ewe breeds known to differ in fertility after cervical artificial insemination with frozen thawed semen

Our previous work indicates that ewe breed differences in fertility following cervical AI with frozen-thawed semen are due to failure of normal sperm transport and/or early embryo development. Here we examined differences in hormone concentrations about the time of ovulation among more (Finnish Landrace and Belclare) and less (Suffolk and Texel) fertile ewes after AI with frozen thawed semen. In Experiment 1, oestradiol concentrations were measured in samples collected frequently from 12 h before to 18 h after the LH surge and progesterone was measured in samples collected from 9 to 27 h after the LH surge in Suffolk ( n = 24), Texel ( n = 20) and Finnish Landrace ( n = 27) ewes. In Experiment 2, oestradiol concentrations were measured in samples collected frequently from 24 h before to 6 h after the LH surge and progesterone was measured in samples collected from 6 h to 6 days after the LH surge in Suffolk ( n = 35) and Belclare ( n = 30) ewes. In Experiment 1, there was an effect of breed, time and their interaction ( P < 0.001) on oestradiol concentrations between −12 and +6 h but only breed differences at +12 and +18 h ( P < 0.01). Progesterone concentrations increased over time ( P < 0.001) and the rate of increase was significantly greater in Finnish Landrace than in the other two breeds. In Experiment 2, oestradiol concentrations were unaffected by breed. There was an interaction between breed and time with the rate of increase of progesterone being greater in Belclare than Suffolk ewes ( P < 0.001). In conclusion, differences in hormone concentrations in the periovulatory period are not consistent with ewe breed differences in fertility; however, we have showed that progesterone concentrations rise earlier in the more prolific breeds and suggest that this may explain reported ewe breed differences in embryo development.

142DETECTION OF LATE EMBRYONIC MORTALITY BY MEANS OF OVINE PREGNANCY ASSOCIATED GLYCOPROTEINS

In sheep, conception rates of 80% are obtained after first mating. Some of the ewes that were not pregnant may have conceived, but underwent embryonic mortality. Embryonic mortality can be distinguished as early (EEM) or late (LEM) embryonic mortality. When EEM occurs, sheep return to estrus 17±2 days after mating, which makes the detection of EEM very difficult. Because determination of ovine pregnancy-associated glycoprotein (ovPAG) concentration can be used for pregnancy diagnosis from Day 25 of conception, with a specificity and sensitivity of 100% and 99%, respectively, it possibly could be used for detection of LEM (Verberckmoes et al., 2003. Pregnancy diagnosis in sheep by means of ultrasound and ovine pregnancy associated glycoproteins (ovPAG), 10th International Symposium on Veterinary Epidemiology and Economics (ISVEE 10), 17–21 November, 2003.). Therefore, in this study the prevalence of LEM and the usefulness of ovPAG concentration for the detection of LEM were examined. In a field trial, serum samples of 160 Texel and 127 Suffolk ewes were collected at the moment of estrus synchronization (T0), and at 25 (T25), 35 (T35), and 45 days (T45) after mating. Concentrations of ovPAG were determined by means of homologous RIA using ovine PAG as standard and tracer, and rabbit antibodies against ovPAG as antiserum. Ewes were considered as being pregnant when ovPAG concentrations were higher than 2ngmL−1. The F-test in a mixed model with ewe as random effect was used to compare the mean PAG concentrations. Of the 287 ewes examined, 5 Suffolk and 2 Texel ewes showed an abnormal PAG profile which was indicative of LEM. The average ovPAG concentration of the 7 former ewes at T25 was 5.6±2.0ngmL−1, which indicates that they were pregnant. However, in contrast to the normal pregnant ewes, they had significantly lower ovPAG concentrations at T35 (2.8±1.5ngmL−1 v. 9.5±2.3ngmL−1) and T45 (0.9±0.3ngmL−1 v. 9.0±1.9ngmL−1) (P&amp;lt;0.01), and they did not lamb at 145±5 days after mating. In conclusion, late embryonic mortality occurred in 2% of the ewes. Determination of the ovPAG concentration by means of homologous RIA is a useful tool for the detection of LEM in sheep.

Comparison of the carcass characteristics and meat quality of lambs produced from Texel and Rouge de l’Ouest ewes and their crosses

AbstractAn experiment was undertaken to compare the carcass characteristics and meat quality of lambs from crossbred ewes produced by crossing Texel sires with Rouge de l’Ouest dams and Rouge sires with Texel dams, relative to lambs from purebred Texel and Rouge ewes. The ewes were crossed with Texel or Rouge sires and the relative performance of the sires assessed in terms of lamb carcass quality. Ewe and ram genotype had a significant effect on conformation classification. Lambs from Texel ewes had a greater conformation classification (4·0) than lambs from Rouge ewes (3·4, s.e. 0·09) (P&lt;0·001) and Texel-sired lambs had a greater conformation classification (4·0) than Rouge-sired lambs (3·6, s.e. 0·06) (P&lt;0·001). Fat depth was significantly influenced by ewe genotype with lambs from Texel × Rouge ewes having greater fat depths compared with lambs from Texel ewes (longissimus dorsi 2·3 and 1·9 (s.e.0·12) mm respectively) (P&lt;0·05). Chemical composition of the carcass and meat quality measurements were unaffected by ewe or ram genotype. Significant heterosis effects on lamb live-weight gain (21 g/day; 15%) (P&lt;0·01) from birth to slaughter, age at slaughter (–37 days; –12%) (P&lt;0·01), weight of perinephric and retroperitoneal fat (76 g; 38%) (P&lt;0·01) and fat depth over the longissimus dorsi (0·3 mm; 16%) and gluteus medius (0·5 mm; 17%;P&lt;0·05) were obtained. The results from this study demonstrate that significant heterosis effects, particularly in terms of lamb growth rate, can be achieved by crossing Rouge and Texel breeds. In addition lambs from hybrid ewes have similar conformation characteristics to the Texel breed which has been intensively selected for carcass characteristics.

Comparison of the productivity of Texel and Rouge de l’Ouest ewes and their crosses

AbstractAn experiment was undertaken to compare the productivity of crossbred ewes, produced by crossing Texel sires with Rouge de l’Ouest (Rouge) dams and Rouge sires with Texel dams, relative to purebred Texel and Rouge ewes. The purebred and crossbred ewes were crossed with Rouge and Texel sires. The proportion of productive ewes was similar in the purebred and crossbred ewes with an average figure of 0·92. Irrespective of crossing sire, Rouge ewes produced 0·48 more lambs per ewe lambed than Texel ewes (P &lt; 0·001). The two crossbred ewe types (Texel ✕ Rouge and Rouge ✕ Texel) each produced similar numbers of lambs (on average 1·92 lambs per ewe lambed). Individual heterosis values for ewe fertility and prolificacy were small and not significant (–1·67 for the proportion of productive ewes and –3·14 for the number of lambs born per ewe lambed). Maternal heterosis values were also not significant but were of larger magnitude (6·26 for ewe fertility and 3·12 for prolificacy). Lamb mortality (number of lambs born dead per ewe lambed) at birth was similar for purebred Rouge (0·44) and Texel (0·30) ewes and was significantly reduced by crossbred matings and mating the crossbred ewes (individual heterosis –30·68, P &lt; 0·10; maternal heterosis –80·23, P &lt; 0·001). Individual and maternal heterosis values for lamb growth rate from birth to six weeks were 8 (P &lt; 0·05) and 4 (P &gt; 0·05) respectively. Lamb growth rate from birth to weaning was significantly lower in lambs from Texel ewes compared with those from the other genotypes (P &lt; 0·05). Individual and maternal heterosis values for live-weight gain from birth to weaning were 5 (P &lt; 0·10) and 5 (P &lt; 0·01). The results of the current study demonstrate the superior performance of purebred Rouge ewes compared with purebred Texel ewes in terms of prolificacy and lamb growth rate from birth to weaning. However, both breeds had high lamb mortality at birth. Crossbreeding led to the production of hybrid ewes which had relatively high prolificacy with low levels of dystocia and lamb mortality.

Relationships among heat production, body weight, and age in Finnsheep and Rambouillet ewes2

It was the objective of this study to quantify heat production across ages of Rambouillet and Finnsheep ewes and to evaluate the previous hypothesis that breed differences can be accounted for by scaling for proportion of mature body weight. Seventy-two Finnsheep and 55 Rambouillet ewes were sampled. Heat production was estimated based on individual animal gaseous exchange, which was determined from 55 through 71 h of the feed restriction. Heat production per unit BW decreased as sheep aged, and the breed-specific functions fit the data better than the pooled functions. The rate of decrease in heat production was greater in Finnsheep ewes until 37 wk of age. The rate of growth of Rambouillet ewes was greater than that of Finnsheep ewes over the first 52 wk of age, and Rambouillet ewes reached 95% of their mature BW at an earlier age (71 wk) than did Finnsheep ewes (113 wk). At any given age, Rambouillet ewes had achieved a greater proportion of their mature BW and had a lower heat production per unit BW than Finnsheep ewes. This study demonstrated the necessity of accounting for both age and breed when estimating metabolic rate in sheep. Furthermore, this study suggested that breed and age differences in metabolic rate could be accounted for by scaling for proportion of mature BW and that daily heat production per unit BW (kcal/kg) of Finnsheep, Rambouillet, Suffolk, and Texel ewes can be described by the function /(BW, matBW) = 59.5e(-0.797(Bw/matBw)), where BW = body weight and matBW = mature body weight.

In situ rumen degradation of dry matter and crude protein in ewes and dairy cows

AbstractComparative studies were performed on the in-situ rumen degradation rate (kd) and the in-situ rumen undegradable residue (U) of dry matter (DM) and crude protein (CP) in sheep and dairy cows. The effect of different treatmentsfor sheep were investigated together with the validity of using cow-based reference protein values of foods for sheep. The effect of different breeds (Texel ewes and crossbred ewes), dietary roughage: concentrate ratio and shearing (mild cold exposure) were investigated for sheep.The in-situ rumen incubations were performed in accordance with standard operational procedures which were comparable for both species. The foods under consideration were hay and concentrates. Cows displayed lower (DM 0·53 , CP 0·86) Kds than sheep for concentrates.For hay a clear trend between cows and sheep was not observed but cows displayed 0·40 lower Kds than Texel ewes and 0·30 higher Kds than crossbred ewes. For concentrates U levels did not differ between species but for hay cows had 0·45 higher U values than Texel ewes. Texel ewes showed 0·45 higher Kd and 0·35 lower U for DM and CP than crossbred ewes. Dietary roughage: concentrate ratio in sheep diets did not influence the Kds and Us of the foods under consideration. Shearing of crossbred ewes increased Kd of CP by 0·25 and reduced U for DM and CP by 0·20 and 0.24 .In conclusion different in situ rumen degradation rates were found between dairy cows and sheep. This probably makes using reference protein values of foods invalid for sheep since they are based on data for cows. Differences (Kd andU) were also found between sheep breeds and between unshorn and shorn crossbred ewes (mild cold exposure). No effect on rumen degradation kinetics could be attributed to dietary roughage: concentrate ratio.

A comparison of sires of Suffolk and Dutch Texel breeds and ewes of Greyface, Suffolk Cheviot and Dutch Texel breeds in terms of food intake, prolificacy and lamb growth rates

AbstractA comparison was made over 2 years of sires of Suffolk and Dutch Texel breeds and ewes of Greyface (Border Leicester × Scottish Blackface), Suffolk Cheviot and Dutch Texel breeds in terms of food intake, prolificacy and lamb growth rates under a grass-based system of production. Suffolk Cheviot ewes consumed significantly more silage dry matter than the Greyface ewes in both years of the study. There was no overall difference between Greyface and Suffolk Cheviot ewes in terms of prolificacy. However lambs from Suffolk Cheviot ewes had a higher growth rate than lambs from Greyface ewes from birth to weaning in year 1 (P &lt; 0·01). In the comparison of the three ewe breeds sired by Dutch Texel rams in year 2, Dutch Texel ewes produced a similar number of lambs to the other genotypes but had a higher incidence of difficult lambings, higher lamb mortality and consequently a lower number of lambs weaned. Purebred Dutch Texel male lambs had lower growth rates than crossbred Dutch Texel lambs (143 compared with 158 glday for lambs from Greyface ewes and 166 (s.e. 13.4) glday for lambs from Suffolk Cheviot ewes in year 1 and 183 compared with 251 and 248 respectively (s.e. 10.9) glday in year 2). Lambs sired by Suffolk rams had higher growth rates than those sired by Dutch Texel rams (252 compared with 224 (s.e. 5.4) glday) in year 2.

Determination of corpora lutea numbers in booroola — texel ewes using transrectal ultrasound

Ovulation rates in Booroola — Texel ewes are currently determined by laparoscopic examination of the ovaries during the luteal phase allowing for carrier status of the ewe to be diagnosed. However, this is an invasive procedure and the aim of this work was to determine whether or not transrectal ultrasound would be an acceptable and accurate alternative to laparoscopy for this purpose in ewes. Transrectal ultrasound was performed using a 5.0 MHz transducer in 18 ewes restrained in the standing position. They were then euthanized and laparoscopy was performed, following which the reproductive tracts were recovered. An additional 22 ewes were subjected to scanning in dorsal recumbency, using a 7.5 MHz transducer, at various stages of the luteal phase before being euthanized and the reproductive tracts recovered. The ovarian structures identified using each method were then compared. The results demonstrated that laparoscopy is an accurate method of determining ovulation rates in ewes. Transrectal ultrasound examination appeared to be an acceptable and non — invasive procedure. The use of a 7.5 MHz transducer with the ewes in dorsal recumbency produced the best results and clearest images of the ovaries, which allowed for the determination of the number of corpora lutea (CL) and the presence of other structures. Accuracy improved with experience in the technique, the stage of the luteal phase at which the examination was performed, the number of CL present in the ovary and the age of the ewe. Further work is needed to confirm this finding due to the small numbers of animals in the present study. This ultrasound technique, however, has the potential to provide an alternative to laparoscopy for the determination of numbers of CL in ewes.

Effects of Texel or Rouge de l’Ouest genes in lowland ewes and rams on ewe prolificacy, lamb viability and weaned lamb output

AbstractAn evaluation of the effects of the proportion of Texel or Rouge de l’Ouest (Rouge) genes in ewes (0, 0·5 or 1·0; the remainder being Greyface (Border Leicester × Scottish Blackface)) on prolificacy, lamb viability and lamb output was undertaken. A comparison of Texel and Rouge sires was carried out on Greyface, Texel and Rouge ewes. Prolificacy was higher in Greyface compared with Texel ewes (P = 0·06) but was lower in Greyface compared with Rouge ewes (P &lt; 0·001). Prolificacy was similar in Greyface and Texel × Greyface ewes mated to Texel rams and in Greyface and Rouge × Greyface ewes mated to Rouge rams. The level of dystocia was similar in Greyface and Texel × Greyface ewes but significantly higher in Texel ewes (P &lt; 0·001). The proportion of Rouge genes in the ewe had no effect on the level of dystocia. Litter weight of lambs at birth was significantly heavier in Greyface (P &lt; 0·001) and Texel × Greyface (P &lt; 0·01) ewes compared with Texel ewes. The proportion of Rouge genes in the ewe had no significant effect on litter weight. Lamb mortality (no. of lambs born dead and died birth to weaning) was significantly greater with Rouge ewes compared with the other ewe breed types (P &lt; 0·001). The number of lambs which died from birth to weaning was lower with Texel × Greyface compared with Greyface ewes (P &lt; 0·01). Expressed on a unit metabolic weight basis, Greyface ewes produced a significantly greater weight of lamb compared with Texel (P &lt; 0·05) and Rouge ewes (P &lt; 0·001). Texel × Greyface ewes produced a significantly greater weight of Texel-sired lamb compared with Greyface (P &lt; 0·01) and Texel ewes (P &lt; 0·001).Sire had a significant effect on a number of parameters. The number of productive ewes was significantly lower in ewes mated with Texel sires (P &lt; 0·001). Lamb birth weights and pre-weaning growth rates were greater with Rouge sires (P &lt; 0·05). Number of lambs weaned per ewe lambed was significantly greater with Texel sires (P &lt; 0·01). Overall weight of weaned lamb produced per ewe was not significantly affected by sire breed.

Circulating levels of inhibin and FSH during the oestrous cycle in 4 genotypes of sheep with different reproductive performances

Two relatively fecund genotypes (Flemish Milksheep and KU-Lovenaar—an F 2 cross-bred originating from pure-bred Suffolk and Flemish Milksheep) and two meat-type breeds (Texel and Suffolk) were compared regarding their plasma inhibin and FSH levels. Oestrus was synchronised by progestagen-impregnated sponges. Blood sampling, starting 12 h after the sponge removal, continued twice daily for 21 consecutive days. To localise the pre-ovulatory LH peak and to determine the cycle length, sampling at 2 h intervals was carried out during the first 3 days and the last 4 days of the 21-day period. Immunoreactive inhibin was measured by a 5-24 α-subunit inhibin assay as well as by an assay based on an antiserum against native bovine 31-kDa inhibin (Monash assay). Changes in plasma concentration of immunoreactive FSH and LH during the oestrous cycle agree with the literature data. The profiles generated by the two different inhibin RIAs were different and showed a negative correlation during the periovulatory phase and on days 9–11. No characteristic pattern could be observed during the oestrous cycle. Significant breed differences were observed for 5-24 α-subunit inhibin as well as for inhibin, measured by the Monash assay. The significantly higher ( P<0.05) 5-24 α-subunit inhibin and lower inhibin (Monash assay) concentration in Texel ewes resulted in a differential ratio of both inhibin measurements for the Texel in comparison with the other breeds. No significant breed differences for FSH were observed during the oestrous cycle. It is concluded that, although significant breed differences in inhibin concentration are observed, the FSH-inhibin interaction is not the only factor responsible for breed differences in ovulation rate.

Rick factors for seroprevalence of ovine lentivirus in breeding ewe flocks in Nebraska, USA

The prevalence of and risk factors for ovine lentivirus (OLV) infection in 1466 breeding ewes in nine US Meat Animal Research Center (MARC) flocks were determined using a recombinant transmembrane protein (rTM) enzyme-linked immunosorbent assay (ELISA) to detect serum anti-OLV antibodies and define infection. Based on multivariable logistic regression, confinement birth and rearing (odds ratio (OR) = 1.6), older weaning ages (OR = 1.1 week −1), and older age (OR = 1.3−2.5 year −1 beyond age 1 year) were significantly associated with higher OLV prevalence in ewes. Prevalence also varied significantly by flock, with Finnsheep and Texel ewes having the highest prevalences and Booroola Merino and Suffolk ewes having the lowest prevalences. These findings support the hypothesis that management control efforts should concentrate on events early in the life of sheep, as this period is associated with factors which can modulate the risk for OLV infection.

The effect of litter size, age of ewe and Booroola gene (Fee B) on the birth and placental characteristics of Texel ewes

It is widely recorded that placental weight varies a great deal in uniformly treated ewes, yet this variation remains unexplained (Mellor, 1983). The aim of this experiment was to assess the effects of differing parameters on birth weight, placental weight, and number and weight of cotyledons in Texel ewes carrying the Booroola fecundity gene.

Relationships among heat production, body weight, and age in Suffolk and Texel ewes

The objective of this study was to test the null hypothesis that heat production (HP) was equivalent between Suffolk and Texel ewes at common fasted BW and at common ages. Open-circuit respiration calorimetry was used to estimate HP in 48 Suffolk and 48 Texel ewes at eight ages (10, 15, 20, and 28 wk of age and 1.5, 2.5, 3.5, and 4.5 yr of age). Sheep were individually penned in an environmentally controlled building 6 to 10 d before sample collection. Feed was removed 55 h before sample collection. Heat production measurements were made from 55 and 71 h of the feed restriction. Suffolk ewes had greater mature weights (P < .01) and reached maturity more rapidly than Texel ewes (P < .05). At a common weight, Texel ewes had a lower HP than Suffolk ewes. The ratio of HP:BW declined as ewes aged, as indicated by the fact that the slope of the log-transformed data was negative and less than 1 (P < .01). The models predict that Suffolk ewes had a lower HP:BW than Texel ewes at a common age, but when ewes were compared at common proportions of mature weight HP:BW did not differ between breeds. Breed differences in HP seem to be the result of differences between breeds in maturing rate.

The effect of long photoperiod or bromocryptine treatment on prolactin concentration and fertility in ewe lambs mated at induced oestrus

AbstractAn investigation was conducted into the effects of increasing plasma prolactin concentration with long photoperiod or suppressing it with bromocryptine on the fertility of ewe lambs. One hundred and twenty dim Forest ewe lambs were divided into three groups: group C was kept as a control; group L was exposed to a long photoperiod (16 h light: 8 h dark) and group B was given daily injections of 1 mg bromocryptine from 12 days before until 21 days after mating. All three groups were mated in late November, 30 days after housing, following progestagen/PMSG treatment. Post-mating prolactin concentrations were significantly higher in group L and lower in group B compared with group C (P &gt; 0·05). There was a tendency for pregnancy rate and the number of corpora lutea to be represented by viable foetuses to be lower in group L than in group C (P &lt; 0·05). Furthermore, post-mating progesterone concentration was higher in this group compared with those in group C (P &gt; 0·05). In a second experiment, 100 Welsh Χ Texel ewe lambs were given treatment C or L. Embryo survival tended to be lower and crown rump length, embryo weight and amniotic sac width were reduced at 25 days post mating in the animals given treatment L, compared with those given treatment C (P &lt; 0·05). The combined results of the experiments indicated that fewer corpora lutea were represented by viable embryos or foetuses in group L than in group C (P &lt; 0·05). These results suggest that embryo growth and survival is reduced in animals bred under a long photoperiod.