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Aim. The effectiveness of the use of the mineral feed additive bischofit in the diets of young sheep in the South of Russia at various doses and its impact on the productive qualities of young sheep. Materials and Methods. The material for conducting the experiment in this household was the livestock of sheep of the Grozny breed on fattening. The sheep of the control group received a basic household diet, the I experimental group received 5 ml of bischofite per head per day in addition to the main diet, the II experimental group received 8 ml of feed additive. Classical zootechnical methods were used in the process of work, including wool yield and physical and technological properties were studied individually in 3 experimental animals from each group according to the VNIIOK method. The research materials were processed by the methods of variation statistics using the Microsoft Office software package. Results. Young sheep from the I experimental group, who received bischofite at 5 ml / head per day, were 9.4% more in live weight than in the control group. Young sheep that received 5 ml of feed additive had the best meat index, and exceeded the control group in terms of pulp yield by 12.5%. The maximum deviation from the average value of the cut of pure wool in the upward direction (110.6%) was observed in I experimental group. The most durable wool of 7.24 sN / tex is found in the group that received the bischofit feed additive as part of the main diet. Conclusion. To compensate for the lack of mineral substances of the natural and environmentally safe feed additive bischofit at a dose of 5 ml / head per day, it changes the metabolic reactions in the body in a positive way, which is confirmed by an increase in the growth of live weight and wool productivity.

This publication presents the results on the growth, development, live weight, body indices in ram lambs and ewe lambs of three-breed crossbreeds ♀ (♀Karakul 18.7% x ♂Avassi 31.3%) x ♂Assaf 50.0% and purebred Assaf, as well as the dynamics of the live weight gain of lambs from birth to 4–4.5 months of age. Crossbreed lambs are developed better than purebred lambs. The absolute weight gain in the ram lambs ♀ (♀Karakul 18.7% x ♂ Avassi 31.3%) x ♂Assaf50.0% was 4.8 kg, which is by 0.32 kg (7.1%) higher in relation to the ram lambs of the Assaf breed, the average daily weight is also higher by 5.4 g. According to the same trend, crossbred ewe lambs had a gross weight gain of 3.72 kg or by 0.22 kg (6.3%) more than in purebred ones and the average daily weight are also higher by 3.2 g. Of the eight body indices, crossbred ram lambs and ewe lambs have five indices that exceed the obtained indicators in purebred animals, and in purebred lambs only three body indices are superior. In ram lambs of the Assaf breed, the indicators for three indices are higher in comparison to crossbreeds: transverse by 0.78%, chest by 0.5% and robustness by 4.65%, and for three-breed crossbreeds they are higher in relation to purebred ones according to the following 5 indices: body format by 4.33%, massiveness by 1.28%, bones by 0.58%, forehead width by 3.74% and head length by 1.42%. The indices of body format, bones and head length are also higher in the purebred ewe lambs by 0.12%, 0.46% and 1.36%, and in the crossbreeds the indices of transverse, massiveness, chest, and head width are higher by 1.21%, 1.35%, 2.02%, 0.29% and 2.97%. The slaughter qualities of crossbreeds are higher for the most indicators taken into account, with the exception of the area of sheepskins. The slaughter weight of crossbred ram lambs is higher by 1.62 kg (13.2%) compared to purebred ram lambs, and the slaughter yield of carcasses is also higher by 2.88%. After deboning chilled half-carcasses, the mass of meat was higher in crossbred animals in comparison to purebred animals by 0.59 kg or 14.8%. All this denoted an higher meat ratio characterizing the relative development of bones and muscle tissues in crossbred animals with made up 2.51 vis-a-vis 2.34 in purebred ones. The highest weight of sheepskins was in crossbred ram lambs and amounted to 3.76 kg, which is by 0.65 kg or by 20.9% more than in peers. At the same time, purebred ram lambs had the largest sheepskins area of 80.3 dm2, which are by 5.52 dm2 (8.51%) more than in crossbreeds. The interior parameters of the internal organs, the development of the digestive organs are closely related to the constitutionally productive characteristics of sheep. The internal organs of crossbred ram lambs, which also have the greatest pre-slaughter live weight, are somewhat better developed. At the same time, they surpassed their purebred peers in the mass of the lungs, spleen and kidneys. The weight of the lungs indicates the volume of respiration and the redox processes occurring in it, on which depend the health and endurance of animals. There were no significant differences in the absolute weight of the lungs in both groups of animals and they were almost the same and ranged from 0.550 g to 0.555 g. Thus, our results indicate that there is a positive relationship between the productivity of ram lambs and the development of their internal organs. The digestive organs and their development ensure the future productivity of the animal. Crossbreed lambs by weight of the stomach without the contents of 973.2 g exceed they peers by 1.4%. The total length of the intestine also for this group of ram lambs is 36.38 meters or more than by 2.36%. In total, all this can lead to better use of the feed, increasing its digestibility. At the ends of the slaughter were taken from each carcass their measurements and the indices were calculated. In crossbred three-breed ram lambs, all carcass evaluation indices are higher in comparison with purebred ones, with the exception of the chest depth index. The lamb leg development index in crossbreeds is significantly higher by 22.52% (P

Aim. Study the effect of low-intensity laser radiation on the genotype's young sheep (poll Dorset x North Caucasian meat-wool) and their exterior. Material and Methods. Zootechnical, biophysical, statistical and other methods were used in research. Experimental animals were exposed to an STP laser apparatus, the action of which is based on the use of low-intensity laser radiation in the infrared region of the spectrum. The study of measurements of animals at the age of 5 and 7 months was carried out and physique indices were calculated. Results. Comparing measurements in the studied animals at 5 months of age revealed the advantage of lambs of groups II and III over the control, in almost all main parameters. However, the experimental groups' young animals were characterized by higher rates of breast measurements. Thus, the superiority of lambs of groups II and III over animals of the control group were: in chest depth 2.1-3.3%, width – 4.4-7.1%, girth – 1.2-4.1% (P < 0.001). A similar trend was established due to measurements of the studied animals' physique at the age of 7 months. At the same time, a clear advantage in terms of measurements characterizing breast development was found in young animals of the second and, especially, in the third group: in chest depth by 3.8-7.4%, width by 4.8-9.1%, girth – 3,7-9.0%, with a significant difference (P < 0.05; P < 0.001). It was also found that the greatest value of the breast index at 5 months of age was typical for animals of groups II and III (77.6-78.6%), which is 1.8-2.8 abs. percent (P < 0.001). However, with age, the difference in the value of this indicator between the groups decreased. Therefore, at the age of 7 months, young animals of groups II and III surpassed animals of group I in this indicator by 0.8-1.5 abs. percent. Conclusion. Thus, it was found that the best ratio of most body articles and body build indices, characterizing them as animals with well-pronounced meat forms, were animal groups II and III.

The purpose of the research is analysis of infection with intestinal cestodosis of young sheep in the plain and mountainous zones of the Republic of Dagestan.Materials and methods. For a number of years, on the basis of the Caspian Zonal Scientific Research Veterinary Institute – Branch of the Federal State Budgetary Scientific Institution “Federal Agrarian Scientific Center of the Republic of Dagestan”, of the laboratory for the study of infective diseases of livestock and birds, we carried out studies of sheep fecal specimens from various regions of the Republic of Dagestan and tested various antiparasitic drugs.Results and discussion. It has been established that sheep cestodosis are ubiquitous in the Republic, although there are effective antiparasitic drugs, including those of domestic production. The infection extensity by Moniezia sp. in 2015 was 67.8%, Thysaniezia sp. – 12.5%, and Avitellina sp. – 6.2%. In 2016, infections continued to be recorded at a high level. In 2017, monieziosis of lambs was recorded with the infection extensity of 24.0–30.0% and with the infection intensity value of 1.5–6.4 sp. per animal. Avitellinosis was noted in 17.0–23.6 % of sheep with an infection intensity value of 1.0–4.8 sp. per animal. Cestodosis in sheep in 2019 are also found, but less frequently.

The feeding factor is an important condition in ensuring the normal life of the sheep. Any external abnormalities cause metabolic stress, the parameters of the biochemical profile change, and the analysis of the development of internal organs in sheep in the post-embryonic period is of great scientific interest, since the absolute mass of organs increases during ontogenesis. Any external abnormalities cause metabolic stress. The parameters of the blood's biochemical profile change. Analysis of the development of internal organs in sheep in the post-embryonic period is of great scientific interest. This is because the mass of organs increases during ontogenesis. Purpose of research. To study the results of the influence of biochemical parameters of blood serum in young sheep on the formation of internal organs against the background of liposomal form of antioxidants with the inclusion of iodine. The research methods. The control group of young animal (rams) received the basic diet (BD). The experimental group received the BD with the addition of antioxidants in liposomal form with organic iodine content at the rate of 5 grams per head. The biochemical parameters of blood serum, the development of internal organs of young sheep and the correlation relationship of the obtained indicators were determined. Results research. Liver and pancreatic enzymes have a significant advantage in animals of the experimental group by 11.5–25.1 % (p ≤ 0.01). The significant advantages for renal enzymes were observed in experimental animals by 10.7 % (p ≤ 0.05) was stated. The total thyroxine content in young animals of the experimental group increases by 5.3 % (p ≤ 0.05). Organs of the gastrointestinal tract were characterized by increased weight. The relationship between the development of internal organs and serum enzymes were enhanced between hepatic and renal enzymes in connection with the development of digestive organs in young animals of experimental groups. The novelty. The liposomal form of antioxidants allows selective delivery of vital compounds to tissues in optimal concentrations. The effectiveness of its use in sheep farming has not been studied, and in connection with the prospect of increasing the production of lamb in the Republic of Crimea, the issue of obtaining environmentally friendly products with minimal use of veterinary drugs and chemical-based feed additives becomes urgent. Thus, the use of antioxidants in liposomal form is a significant step towards achieving this mission.

The purpose of the research is studying the effect of mechanochemical technology on anthelmintic efficacy of supramolecular complexes of fenbendazole with licorice extract. Materials and methods. Tests of the supramolecular complexes of fenbendazole (SMCF) with licorice extract (LE) were carried out on 127 heads of young sheep spontaneously infected by Nematodirus sp. and other types of gastrointestinal strongylates. For each helminthosis, animals of different groups of 8–11 animals each were given single oral administration of SMCF with LE in a dose of 2.0 mg/kg in AD in the form of 10 and 17 % powders and 2.4 and 4.5% suspensions in comparison with the basic drug – fenbendazole (FBZ) in a dose of 2.0 mg/kg. SMCF with LE was developed according to mechanochemical technology for 2 hours. The baseline was a group of sheep that did not receive the drug. The anthelmintic efficacy of the preparations was taken into account according to the results of coproovoscopic studies of sheep by flotation before and 16 days after the preparations were used. Accounting for the effectiveness of drugs was carried out according to the "control test" type. Results and discussion. SMСF with LE in a dose of 2.0 mg/kg by AD in the form of 10 and 17% powders and 2.4 and 4.5% suspensions showed respectively 89.2; 83.12; 82.09 and 83.59% effectiveness against Nematodirus spp. and 88.73; 67.3; 83.87 and 86.38% activity against other types of Strongylata when receiving 22.7 and 21.9% effect of the base drug – FBZ.

Flystrike remains a serious financial and animal welfare issue for the sheep industry in Australia despite many years of research into control methods. The present paper provides an extensive review of past research on flystrike, and highlights areas that hold promise for providing long-term control options. We describe areas where the application of modern scientific advances may provide increased impetus to some novel, as well as some previously explored, control methods. We provide recommendations for research activities: insecticide resistance management, novel delivery methods for therapeutics, improved breeding indices for flystrike-related traits, mechanism of nematode-induced scouring in mature animals. We also identify areas where advances can be made in flystrike control through the greater adoption of well-recognised existing management approaches: optimal insecticide-use patterns, increased use of flystrike-related Australian Sheep Breeding Values, and management practices to prevent scouring in young sheep. We indicate that breeding efforts should be primarily focussed on the adoption and improvement of currently available breeding tools and towards the future integration of genomic selection methods. We describe factors that will impact on the ongoing availability of insecticides for flystrike control and on the feasibility of vaccination. We also describe areas where the blowfly genome may be useful in providing impetus to some flystrike control strategies, such as area-wide approaches that seek to directly suppress or eradicate sheep blowfly populations. However, we also highlight the fact that commercial and feasibility considerations will act to temper the potential for the genome to act as the basis for providing some control options.

El objetivo de esta investigación fue establecer valores de referencia en las concentraciones de la hormona estimulante de la tiroides (TSH, del inglés Thyroid-Stimulating Hormone) y tiroxina (T4) libre, para los pequeños rumiantes menores de 7 meses, analizando la influencia del sexo sobre las determinaciones. Se obtuvieron muestras de sangre de 48 ovinos en estado de ayuno (25 machos y 23 hembras menores de 7 meses de edad), las concentraciones de TSH y T4 libre se determinaron mediante inmunoensayo enzimático. Los valores de TSH para las hembras jóvenes (μUI/ml) fueron: promedio, mínimo, máximo y desviación estándar de 0,34; 0,0; 0,57; 0,15, respectivamente. Para los machos jóvenes fueron: 0,09; 0,0; 0,57; 0,15, respectivamente. El valor p del test F fue 0,147 (p ≥ 0,05), por lo cual no hay diferencia estadísticamente significativa con una confiabilidad de 95 % para la TSH en ovinos jóvenes con respecto al género. Los valores de T4 libre para las hembras jóvenes (ng/dl) fueron: promedio, mínimo, máximo y desviación estándar de 0,44; 0,13; 0,73; 0,21, respectivamente. Para los machos jóvenes fueron: 0,66; 0,31; 1,17; 0,24, respectivamente. El valor de p del test F es 0,04 (p < 0,05), lo cual evidencia diferencia significativa con una confiabilidad del 95 % para los valores de T4 libre en ovinos jóvenes. Se concluye que el sexo causa variación en la secreción de T4 libre en los pequeños rumiantes jóvenes.

Animals suffering from parasitism typically display altered grazing behaviour and a voluntary reduction in feed intake. These changes are potentially important as indicators of disease. Recent advances in sensor technologies provide the opportunity to objectively measure animal activity while on pasture. Tri-axial accelerometers measure body movement in terms of acceleration, which can then be used to estimate physical activity over time. This study investigated if tri-axial measures of overall activity can be used to assess the impact of gastrointestinal nematode (GIN) infection in young sheep. To address this, the overall activity, faecal nematode egg count (FEC) and body weight of two treatment groups of Romney X Suffolk ram lambs were compared. Animals were monitored for four days using tri-axial accelerometer sensors mounted on a ram mating harness after 42-days grazing on contaminated pasture. On Day 0, all lambs were given anthelmintics. Subsequently, a Suppressive Treatment Group (n = 12) was treated with anthelmintics every two weeks. An Untreated Group (n = 12) did not receive further anthelmintics. Overall activity levels were monitored from Day 42 – 46. Activity level was calculated as vectorial dynamic body acceleration (VeDBA). Anthelmintic treatment had a significant effect on FEC but there was no evidence found for a treatment effect on body weight growth over the 42-day period. An effect of treatment and lamb starting weight on overall activity was found (beta = –0.74, 95 % CI –1.17 to –0.30, p = 0.002), identifying a negative impact of parasitism on activity in heavier animals. These results highlight the usefulness of this approach in assessing the effect of GIN parasitism on sheep monitored remotely. If a threshold value of activity could be determined, it could provide a useful tool for farmers and managers that serves as an early indicator of parasitism in sheep.

Objective of research: The study of eosinophilic reaction in blood at experimental dictycaulosis of young sheep and after providing the complex therapy. Materials and methods: The research was conducted in August- September 2013at an experimental farm «Kurilovo» in Podolsk district of Moscow region. Six mongrel lambs at 4–5 months of age, free from infection, and 18 lambs experimentally infected with Dictyocaulus filarial at gtye dose of 1000 larvae per head were investigated. 30 days after invasion, lambs were divided into 3 equal groups (6 head in each) and kept under conditions excluding the possibility of spontaneous invasion. Lambs of the first group free from infection, served as controls and did not receive the drug. Infected animas of the second group were not treated and served as controls. Lambs of the third group received Alben as 20% granulated powder at the dose of 5 mg a.i./kg (0,25 g of granules per 10 kg of body weight); the fourth group of lambs received Alben at the same dose and subcutaneously T-activin at the dose of 2 mkg/kg once a day on the 1st , 3rd and 7th day of invasion, and В-activin at the dose of 5 mkg/ kg intramusculary once a day during 5 days. Before the experiment and after 7, 15, 30 and 60 days of treatment, blood samples were taken from calves. Trilon B was used as anticoagulant. Blood eosinophil levels were measured by the standard method. Results and discussion: Persistent blood eosinophilia was determined at experimental dictycaulosis in lambs. The level of eosinophils cannot be fully restored by dehelmintization with Alben. The full restoration of the quantity of eosinophils in blood of infected lambs occurs after the complex therapy with Alben in combination with T and В-activin.

The article presents the results of a study of meat efficiency of young Kazakh fat-tailed breed grubosherstnoj. The object of the study were rams, valushki, Mutton studied breed. The obtained data and their analysis shows that intensive cultivation of rams, and valushkov yarochek improved the slaughter qualities, as evidenced by the increase in slaughter yield with age. Rams, and Mutton valushki Kazakh fat-tailed breed grubosherstnoj distinguished by high slaughter qualities. This determines its prospects of breeding for high biological value of meat - lamb.

Studied the effect of organic and inorganic forms of iodine preparations on blood biochemical parameters and feeding qualities of young sheep. Studies were carried out in the Stavropol Territory, endemic iodine. On the North Caucasian sheep breed. The analysis of the results obtained, it was found that the use of iodine preparations, giving raise to 12.35% glucose, triglycerides by 11.55% to 20.15% chloride, 5.95% cholesterol, reduce the level of alkaline phosphatase per 89%, as well as improve other performance. The best results were obtained from animals of the second experimental group, which was added to the basic diet drug organic forms of iodine - Yoddar. Gain in the second group as well was the most high and amounted to 13.04 kg.

The article shows the development of the main departments of the muscle tissue depending on the genotype, sex, age and physiological state. It is established that, as in certain age periods, and during cultivation, the highest growth rate, as muscle mass halves, and its divisions, was the difference barancik all genotypes, and the minimum of jarocki, valoski took an intermediate position.

Animal habituation is key to obtain reliable data on behavioural studies but detailed procedures to achieve it are scarce. This study designed a set of actions to habituate sheep and goats to human observers. Pelibuey sheep (n = 15) and Criollo goats (n = 10) were classified as (a) avoider, flight from human interaction, or (b) follower, seek human interaction. Habituation was measured by the reduction of flight distance by avoiders, or number of followers in the presence of observers. The habituation protocol consisted of a gradually increased series of five manoeuvres, either challenge (for avoiders) or evasion (for seekers), performed first inside a pen and subsequently in a grass paddock. Habituation was considered successful when animals could be observed from a 1-m distance without flight or following the observer. In the pen, habituation took 12 and 13 days for sheep and goats, respectively. Meanwhile, in the grass paddock habituation took 10 days, for both species. The number of challenge and evasion series was negatively correlated with the flight distance in sheep and with the number of followers in goats. This protocol is simple and practical to implement and enables animal habituation for behavioural studies.

Perfluoroalkylated substances (PFASs) present a potential health risk for consumers. In animals these compounds are known to accumulate in livers. In order to determine potential PFASs contamination in commercially available livers, samples from farmed sheep, horses, cows, pigs and chicken were collected from the Dutch market. PFOS was the only detectable PFAS and its concentration was higher in free ranging animals like cows and sheep. The detected levels of PFOS in the liver samples were very low (up to 4.5 ng g(-1) ww). To further study the kinetic behaviour in foraging animals, samples from a study in which sheep were fed with grass obtained from a river floodplain, were examined. PFOS was the only detectable PFAS in the contaminated grass pellets, showing a level of about 0.5 μg kg(-1). Young blackhead sheep were fed with either clean or contaminated grass for a period up to 112 days. A time-dependent increase in liver PFOS concentrations was observed from 2.4 to 10.9 ng g(-1) ww after 8 and 112 days respectively. A time-dependent depuration was observed in livers of animals switched to clean grass after 56 days of exposure, from 9.2 to 4.7 ng g(-1) ww after 64 and 112 days respectively. The percentage of PFOS ingested from the grass and retained in the liver was estimated to be 12% at day 56, and decreased gradually to 6% after 56 days on clean grass, showing that the decrease in levels is not only caused by an increase in liver weight. Levels detected in commercial livers but also those in the sheep study would not lead to exceedance of the current TDI for PFOS set by EFSA. Therefore, it can be assumed that they do not present a risk for human health.

Articulating cartilage wear plays an important role in cartilage degeneration and osteoarthritis (OA) progression. This study investigated the changes of mechanical properties and surface roughness of sheep cartilages with wear progression at a nanometre scale. Young sheep’s rear legs were subjected to a series of wear tests to generate worn cartilage samples to simulate the OA progression. Atomic force microscopy (AFM) was used to determine the effective indentation modulus and to measure the surface morphology of moist cartilage surfaces. The study has found that the mean effective indentation modulus values of worn cartilages were lower than that of healthy cartilage as the control sample. A medium-to-strong correlation between the effective indentation modulus values and the OA grades has been found. The relation between surface topography and effective indentation modulus values of the cartilage surfaces with OA progression was weakly correlated. The method established in this study can be implemented to investigate the effective indentation modulus values of clinical osteoarthritic cartilages and to assist in the understanding and assessment of OA.

OBJETIVO: Para melhorar as propriedades mecânicas e imunogenicas, o glutaraldeido e utilizado no tratamento do pericardio bovino que e utilizado em bioproteses. A liofilizacao do pericardio bovino tratado com glutaraldeido diminui os radicais aldeido, com provavel reducao do potencial para calcificacao. O objetivo deste estudo e avaliar os efeitos da liofilizacao em bioproteses valvares de pericardio bovino como mecanismo protetor na diminuicao da disfuncao estrutural valvar. METODOS: Foi realizado o implante de bioproteses de pericardio bovino tratado com glutaraldeido, liofilizadas ou nao, em carneiros de 6 meses de idade, sendo os animais eutanasiados com 3 meses de seguimento. As bioproteses foram implantadas em posicao pulmonar, com auxilio de circulacao extracorporea. Um grupo controle e outro grupo liofilizado foram avaliados quanto ao gradiente ventriculo direito/arteria pulmonar (VD/AP) no implante e explante; analise quantitativa de calcio; inflamacao; trombose e pannus. O nivel de significância estabelecido foi de 5%. RESULTADOS: O gradiente medio VD/AP, no grupo controle, no implante, foi 2,04 ± 1,56 mmHg e, no grupo de liofilizacao, foi 6,61 ± 4,03 mmHg. No explante, esse gradiente aumentou para 7,71 ± 3,92 mmHg e 8,24 ± 6,2 mmHg, respectivamente, nos grupos controle e liofilizacao. O teor de calcio medio, apos 3 meses, nas bioproteses do grupo controle foi 21,6 ± 39,12 µg Ca+2/mg de peso seco, em comparacao com um teor medio de 41,19 ± 46,85 µg Ca+2/mg de peso seco no grupo liofilizado (P = 0,662). CONCLUSAO: A liofilizacao de proteses valvares com pericardio bovino tratado com glutaraldeido nao demonstrou diminuicao da calcificacao neste experimento.

A major part of sheep livers contains levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) above the former but to some extent also the new maximum levels (MLs) in the EU. In order to investigate the relationship between the intake of these contaminants and their accumulation in livers, kidney fat and meat, young blackhead sheep were fed with grass pellets containing PCDD/Fs at 2.5 times the maximum level. Levels of PCDD/Fs in livers were already quite high at the start of the exposure but increased 3-fold within 56 d, exceeding the new product based MLs. Levels in meat and fat also increased but did not exceed the MLs. Although less elevated in the grass, both dl- and ndl-PCB levels also increased in liver and fat. Their kinetics in the tissues was less clear, potentially caused by increased levels in the straw given to the sheep during the whole experimental period. There was a clear difference in the behavior of the various congeners, the PCDFs and especially the higher chlorinated PCDFs and PCDDs showing a higher accumulation in the liver. In the case of the PCBs, this was particularly true for PCB 126. When switched to clean grass after 56 d, the levels in livers and other tissues decreased to about the levels in the control sheep within 56 d. This offers a potential solution for decreasing the intake of consumers.

INTRODUCTION: Often, studies on aortic prosthetic valves analyze their performance not at the primitive position, but using tricuspid and mitral ones or inserting it in the descending aortic area. Taking that into account, it would be relevant to observe results in those studies in which the conclusions are based on their original implantation. MATERIAL AND METHODS: Thirty young sheep, 28 males and 2 females, were operated on. Ages ranged 4.4 to 6.3 months and weights 25 to 37 Kg. Extra corporeal circulation (ECC) was applied to all the animals, always guided by the conventional criteria, that is to say, the arterial cannula was inserted in the thoracic aorta just past the arterious ducts and the venous cannulae, a single one, was placed in the right atrium. The operation was performed according to the principle of moderately low body temperature- 29oC- and cold cristalloid cardioplegia, in the aortic root, to induce; but otherwise was utilized blood to the maintenance. Following with the technique proposed, the aortic valve of the animal heart was completely excised and finally implanted the valved tube stentless, not forgetting the refixation of the coronary main. The sheep were kept in clinical and laboratorial observation during thirty days in what was included a echocardiogram in the end. RESULTS: The results demonstrated 8 intraoperatory deaths (26.6%), and 6 during the following (27.7%). The mean time of ECC was 98 minutes. The dimension of the majority prothetics valves were 21 and 23. Only two valves evoluted with mild insufficiency, none denoted evidences of the endocarditis neither of leaflets perfuration, the mean fraction of ejection was 74%, the left ventricle had its wall preserved in all cases. CONCLUSION: This experimental model can certainly reproduce nearly the reality, confirming good parameters of prothetics stentless evaluation in the aortic position. And the sheep declared itself to be pleasant, which helps us its control during the whole study.

A total of 876 sheep from five flocks in north Jordan were selected to study the effect of shearing on the incidence of caseous lymphadenitis (CLA). The animals were divided into two age groups, sheep aged 1-2 years and those agedor = 3 years. Blood samples were collected from the animals at the time of shearing and again 6 months later. A toxin enzyme-linked immunosorbent assay was used to identify sheep that had been infected with Corynebacterium pseudotuberculosis. The point prevalences of CLA were 6.59% and 21.06% in the 1-2-year andor = 3-year age groups, respectively, and were significantly higher (P0.01) in theor = 3-year age group. The overall prevalence among all ages was 15.3%. In the shorn sheep, the incidence of CLA was 22.46% and 9.47% in the 1-2-year andor = 3-year age groups, respectively, and was significantly higher (P0.05) in the 1-2-year age group. In the control animals, the incidence was 8% and 5.26% in the 1-2-year andor = 3-year age groups, respectively, and was different (P0.01) between the shorn (22.46%) and control (8%) animals of the 1-2-year age group. An epidemiological survey of 35 sheep farms revealed the prevalence of CLA, shearing wounds and unhygienic conditions during shearing in all farms. In conclusion, the prevalence of CLA increases with age and the incidence increases only in young sheep after shearing. Sheep are sheared under unhygienic conditions, which may be a contributing factor in increasing both the prevalence and the incidence of CLA.

Biodegradable miniplates and screws offer special possibilities for surgical techniques because the removal operation is avoided. In areas beneath thin skin, intraosseous plating could be preferable to avoid palpability and transient swelling during resorption. The tissue reaction to a 0.5-mm-thick self-reinforced poly-L-lactide (SR-PLLA) plate fixed with an SR-PLLA miniscrew was studied histologically and histomorphometrically after implantation into the calvarium of six young sheep. After follow-up periods of 6, 20, and 52 weeks, no signs of adverse tissue reaction such as clinically manifest foreign body reaction or histologically manifest osteolysis were noted. By 52 weeks the implants were largely in direct contact with remodeled, dense bone tissue. No signs of fragmentation or resorption were noted in the intraosseous parts of the implants, whereas the screw head had been fragmented and was undergoing resorption at 52 weeks. The screw head is unnecessary in this plating method and could have been removed with a hot wire loop. The excellent biocompatibility of the mechanically strong, resorbable SR-PLLA plate with miniscrew fixation provides a possibility for intraosseous plating in less loaded craniofacial areas, especially in areas with very thin soft-tissue coverage.

Objective To confirm the efficacy of ivermectin released from a controlled-release capsule administered to young sheep and to breeding ewes under field conditions. Design Randomised field trials. Procedure In each of ten field trials 25 weaned lambs were treated with ivermectin controlled-release capsules and 25 remained untreated. Eight similar field trials were conducted using adult ewes. Efficacy against infections of gastrointestinal nematodes was assessed by faecal egg counts and faecal larval culture. Body weights were recorded and faecal soiling of the breech wool (dags) was assessed. Results Nematode faecal egg counts in the two groups were not different (P = 0.13) before treatment in the weaner trials or before treatment in the ewe trials (P = 0.49), but thereafter eggs in the untreated sheep persisted, whereas counts in sheep given capsules were negligible (P ≤ 0.01). In the weaner trials, dag scores for the two groups were not different at the start of the trials (P = 0.18) but at the end, untreated sheep had significantly more dags (P = 0.04) than treated sheep. In the ewe trials, dag scores remained low in both groups. Weaners treated with the capsule gained 1.4 kg (95% CL: 0.7, 3.1) more weight over the 16 week trial period compared to untreated weaners (P = 0.01). Both groups of ewes lost weight as a result of parturition but the mean loss by week 16 was greater for untreated (3.7 kg) (95% CL: -5.1,-2.2) than for treated ewes (1.8 kg) (95% CL: -3.3, -0.4). The mean change in ewe body weight for the two groups was however not significant (P = 0.07). Differentiation of nematode larvae recovered from cultures of faeces from untreated animals indicated that the capsules were effective against the common parasites of sheep. Conclusion The capsule was efficacious against gastrointestinal nematodes judging from faecal egg counts. It has the potential to significantly reduce contamination of pasture with nematode eggs. Treated weaners had less dags for 16 weeks and gained more weight than untreated weaners.

The prevalence and numbers of coccidian oocysts in faecal samples from young (less than 6 months old), immature (6-12 months old) and adult (over 12 months old) sheep on 15 farms in Nyandarua district were studied during the dry and wet seasons. The species of Eimeria occurring in these sheep were also identified. The proportion of animals shedding coccidian oocysts did not vary significantly with season. The prevalence of the oocysts was significantly higher (p0.05) in young sheep (mean 85.3%) compared to immature (mean 40.2%) and adult sheep (mean 32.15%). OPG counts (oocysts per gram of faeces) were significantly higher (p0.01) in the young sheep compared to immature and adult sheep during both seasons. Prevalence and OPG did not differ between immature and adult sheep. There was no significant difference in OPG during the wet season (mean 328 +/- 997) compared to the dry season (mean 219 +/- 773). The sex of the sheep had no significant effect on prevalence or OPG. Eight species of Eimeria were recognized. They (and their prevalence) were E. bakuensis (ovina) (43.6%), E. ovinoidalis (23.6%), E. ahsata (15.2%), E. intricata (8.27%), E. granulosa (4.8%), E. faurei (2.8%), E. parva (1.06%) and E. pallida (0.67%).

Sheep were slaughtered after live weight gain (LWG) and live weight loss (LWL) to evaluate the effect of different periods of normal and retarded growth on dissected carcass components. Thirty-five Merino wether sheep were allowed ad libitum access to the experimental diet of 80% alfalfa chaff and 20% cereal grain (17.23% CP and 18.10 MJ/kg of GE) to grow from 23.0 to 33.0 kg live weight and then fed to lose 10 kg at 133 g/d. Five animals were slaughtered at live weights of 23.0, 26.3, 29.6, and 33.0 kg during LWG and 29.6, 26.3, and 23.0 kg during LWL. Fleece-free empty BW was similar in both LWG and LWL animals at all common slaughter weights because of the lesser and greater weights of the alimentary tract contents and the fleece, respectively, in the LWL animals. Carcass weight or dissected side weight was greater in LWL animals at each common slaughter weight but significantly so (P less than .05) at the 23.0 kg live weight only. Total side muscle weight was similar in LWG and LWL animals at each common slaughter weight, but the proportion of muscle in the dissected side weight was lower (P less than .05) in LWL animals at 23.0 kg live weight. Total side fat, subcutaneous fat, intermuscular fat, and kidney and channel fat weights were all greater in LWL animals at each common slaughter weight, but significantly so (P less than .05) at the 23.0 kg live weight only. Total side bone weight was higher at both 26.3 kg (P less than .01) and 23.0 kg (P less than .05) in the LWL animals. Weight loss in young sheep mobilized more weight of muscle than fat from the carcass, whereas bone weight was constant.

Seasonal variation in reproductive activity in Australian goats was investigated in three experiments. In the first, the seasonal incidence of spontaneous ovulations was recorded by monthly endoscopy in mature does and young sheep separated from males during a 12 month period. The sheep began to ovulate in February with a peak incidence in March (95%); the proportion ovulating remained high until July, then declined with no ovulations observed between August and December. In contrast, does did not begin spontaneous ovulation until April, with peak incidence occurring in June (90%); no ovulations were recorded between September and February. In the second experiment, two groups of sheep and two groups of goats were joined in either April or September and mating and births recorded. A high proportion of the sheep and goats mated and fell pregnant at the April joining with 82% of sheep and 88% of goats giving birth. During the September joining 30% of sheep mated and 44% of these lambed. In contrast, 85% of does mated but only 12% kidded. The third experiment recorded ovarian activity by endoscopy at 30–40 day intervals in does either isolated from, or intermittently exposed or continuously exposed to bucks for a 20 month period. In the absence of males does only ovulated between April and August, but exposure to bucks, either intermittently or continuously, extended the ovulatory period to March–September. It is suggested that the annual ovulatory rhythm in does reflects a changing sensitivity to exteroceptive stimuli that initiate reproductive activity. The data presented suggests that there are at least three component phases, an active period of spontaneous ovulation, a responsive phase in which ovulation and pregnancy can be induced in anovular does, and a quiescent phase in which anovular does do not respond to the male stimulus.

This study compares the healing of lesions made in the occipital region of the calvarium of 5 foetal and 4 post-natal lambs. The foetuses, operated on between the 83rd and 91st day of gestation, had a bone flap elevated and the post-natal lambs, aged about 6 weeks, had a craniectomy and replacement of the bone pieces. The foetuses were delivered spontaneously at full-term. All the animals had computed tomographic (CT) scans and, after sacrifice, naked eye examination of the bony lesions. These showed that there was poor ossification of the lesions made in the foetuses compared to those made in the post-natal lambs. These findings need to be taken into account when intra-uterine correction of cranio-facial deformities are being contemplated.

OBJETIVO: Analisar comparativamente o uso do etanol (E) com o glutaraldeído (GDA), como método de inibição da calcificação dos heteroenxertos valvares pulmonares porcinos (HVPP) implantados na via de saída do ventrículo direito (VD) de ovinos jovens. MÉTODO: Foram utilizados dez ovinos jovens, em dois grupos contendo cinco animais cada. A operação consistiu na implantação do HVPP na via de saída do VD com circulação extracorpórea, divididos em dois grupos; o grupo do GDA (controle) e o grupo E (grupo em que os HVPP foram pré-tratados com etanol a 80%). Realizou-se estudo ecocardiográfico para medida do gradiente transvalvar pulmonar, análise macroscópica da parede do HVPP e microscópica quanto à presença de calcificação; e mensuração do cálcio na cúspide valvar após 210 dias. RESULTADOS: Na mensuração do cálcio do HVPP encontrou-se no grupo GDA (7,98 ± 6,82µg cálcio/mg tecido), no grupo E (0,31± 0,33µg cálcio/mg tecido). Em relação ao gradiente transvalvar máximo em 30 dias, não houve diferença significativa entre os grupos, já aos 90, 180 e 210 dias, o grupo GDA apresentou maior gradiente transvalvar do que o grupo do etanol. Na análise macroscópica da parede do HVPP, observou-se calcificação em ambos os grupos, sendo mais intensa no grupo do GDA. Na avaliação microscópica das cúspides do HVPP em relação à presença de calcificação, observou-se que no grupo GDA esteve presente em todos os animais, enquanto no grupo E, esteve ausente em todos. CONCLUSÃO: Conclui-se que etanol a 80% inibe a calcificação das cúspides no período analisado, mas não inibe a calcificação da parede do HVPP. OBJECTIVE: The objective of this work was to comparatively evaluate the use of ethanol (E) with glutaraldehyde (GDA) to inhibit the calcification of the porcine pulmonary valvar heterografts (PPVH) implanted in the right ventricle outflow tract of young sheep. METHODS: Ten young sheep were used, divided into two similar groups: the GDA (control) Group and the Ethanol Group (in which the PPVH were pre-treated with ethanol-80). The surgery consisted of implanting the PPVH in the right ventricle outflow tract using a cardiopulmonary bypass. Echocardiography was performed to measure the transvalvar gradient and macroscopic analyses of the PPVH wall and microscopic analysis for calcification were performed. The amount of calcium was measured in the valve cusp at 210 days. RESULTS: The quantity of calcium in the PPVH of the GDA Group was 7.98 ± 6.82µg calcium/mg tissue and of the E Group it was 0.31± 0.33µg calcium/mg tissue. In respect to the maximum transvalvar gradient at 30 days, there was no significant difference between the groups. At 90, 180 and 210 days however, the GDA Group showed a greater transvalvar gradient than the E Group. The macroscopic analyses of the heterograft wall evidenced calcification in both groups but it was more pronounced in the GDA Group. The microscopic analysis of the cusp valve revealed the presence of calcification in all animals of the GDA Group, while in the E Group no calcification was seen. CONCLUSION: In conclusion ethanol-80 inhibits calcification on the cusps during the period of the analysis but does not inhibit the calcification of the PPVH.

Much of the literature regarding arthrotic changes in the temporomandibular joint (TMJ) is based on the assumption, rather than the demonstration, that joint degeneration is pathologically and biochemically similar to that which has been described for other arthrodial joints. Understanding such changes is axiomatic of an understanding of the specific histomorphometric structure of the normal TMJ, in particular the condyle. Unfortunately, very little has been established about the trabecular bone patterns in the mandibular condyle as it develops. As a consequence of the obvious practical difficulties in investigations of the human TMJ, the sheep has been variously used as an animal model. In order to augment a fuller characterisation of this animal model, this study focuses on the quantitative histomorphometries of the trabeculae in the mandibular condyles of young and mature sheep. Quantitative histomorphometric analyses of condylar trabeculae were performed on histological sections prepared from mature and young sheep condyles. Lateral, central and medial sagittal sections, and anterior and posterior coronal sections of the condyle were analysed using a Quantimet 500MC image analysis system that had been programmed to provide structural index values of trabecular bone volume, surface, thickness, separation and number. Analysis of histoquantitation data revealed a significant concordance in bone structural index values between lateral, central and medial regions in young and mature sheep as well as anterior and posterior regions in young sheep. Moreover, there was little significant variation between similar regions in the respective age groups. This study provides the first comparative histomorphometric quantitative analysis of the trabeculae in the mandibular condyle of both young and mature sheep. The findings of this study reinforce the appropriateness of the sheep TMJ as a model in previous experimental studies of the bony architecture of the condyle.

This paper reports on three trials set up to evaluate Grasslands Advance tall fescue, a new cultivar bred by Tall fescue (Festuca urundinacea Schreb.) pastures AgResearch Grasslands. in New Zealand have been considered to have slow establishment (Grasslands Roa) or lower Methods summer quality (the faster establishing AU Triumph). Three experiments were conducted to Trial 1: Establishment study the establishment vigour, herbage production This experiment was sown on an irrigated Wakanui and animal growth rates of a new tall fescue silt loam at Lincoln in mid September 1992. Three cultivar, Grasslands Advance. Establishment replications of Grasslands Roa, Grasslands Advance vigour of Advance was similar to that of Au and AU Triumph were sown in 20 m drill rows with an Triumph and 30% greater than that of Roa. Oxford precision seed drill (9 coulters). Seeding rates Advance and AU Triumph were 17 and 8% higher were adjusted to sow 100 viable seeds per metre row in annual grass production than Roa, with Advance (equivalent to 17 kg/ha). Six weeks after sowing, whole significantly out yielding the other two cultivars plants were harvested, counted, dried and total root in the warm season. Animal performance per head and shoot growth weighed. Twelve 250-mm row lengths of young sheep on Roa was significantly higher per plot were taken for this measurement. than on AU Triumph in spring, both Advance and Roa having a significant advantage over AU Trial 2: Herbage production Triumph in the warm season. This trial site was a free draining Manawatu fine sandy loam overlying medium - coarse sands and deep gravel.

Objective To assess the effectiveness of intramuscular injection of copper heptonate (CuHep) and an oral dose of copper oxide wire particles (COWP) in preventing Cu inadequacy in adult and young sheep on pasture of high Mo content. Design Field experiments with flocks of mature Merino wethers and crossbred weaners. Procedure Adult wethers were given 25 or 37.5 mg Cu as CuHep, 2.5 g COWP or no Cu treatment. The weaners were given 12.5 or 25 mg Cu as CuHep, 1.25 g COWP or no Cu treatment. At intervals over the next 12 (adults) or 8 (weaners) months the sheep were weighed and samples of blood and liver were collected for trace element assay. Wool samples collected from the adults at the end of the experiment were assessed for physical characteristics. Results The higher dosage of CuHep raised liver Cu above control group values for at least 9 months in adults and 3 months in weaners. The lower dosage of CuHep was similarly effective for 3 months in adults but was without effect in weaners. In adults the response to COWP matched that to the higher dosage of CuHep; in weaners it was greater, lasting at least 5 months. No changes indicative of Cu deficiency, apart from a depressed body weight in adults, were seen. Conclusions In sheep on pasture of high Mo content a single intramuscular injection of CuHep providing 37.5 mg Cu to adults or 25 mg Cu to weaners will raise liver Cu reserves for at least 9 and 3 months respectively and may be an acceptable alternative to COWP for preventing seasonal Cu deficiency in sheep in southern Australia.

Filiform squamous papillomas occur rarely on young sheep and correspond closely to those on cattle and other species; they lack the fibromatous component of papillomas reported previously. This paper describes microscopical, immunological and molecular evidence for the presence of a putative ovine papillomavirus in these lesions.

The development of an enzyme-linked immunosorbent assay (ELISA) for the detection of Babesia ovis antibodies is described. In an initial study, a crude Babesia bovis antigen and a synthetic B. bovis -derived antigen (designated 11C5) were used to screen 46 B. ovis -positive and 55 negative sheep sera. A 95% correlation between the two antigenic preparations was found with the positive sera; no negative sera gave positive reactions. The synthetic antigen was then used in the screening of 1466 sera collected from sheep from 18 regions of Turkey. A high incidence of B. ovis -positive reactions was found from all regions (60–80%) in sheep over 1 year old, while from two smaller samples the incidence in young sheep was much less (28 and 52%). This test is superior to existing ones because the synthetic antigen can be produced in a highly reproducible state, is specific and is stable over extended periods of time.

We investigated the influence of age of exposure to a specific forage on its consumption by young sheep both during and after that exposure. Prior exposure to the shrub Cercocarpus montanus enhanced subsequent consumption (P less than or equal to .05) of that shrub by lambs and yearlings during two experiments in consecutive years. Effects of prior exposure persisted as long as 9 mo without intervening exposure. Age of exposure influenced consumption in lambs both during the period of exposure (P less than or equal to .0001) and during feeding trials following exposure (P less than or equal to .07) in Exp. 1. Lambs exposed at 1 to 5 wk of age, when they are nonruminant and normally are dependent on the dam, browsed less of the time while at the shrub (P less than or equal to .02) and consumed less of the shrub (P less than .02) at a slower rate (P less than or equal to .03) than did lambs exposed at older ages. Lambs exposed at 4 to 8 wk of age, a period corresponding to the transition from nonruminant to ruminant digestion, consumed more shrub following exposure than did lambs exposed at younger or older ages (P less than equal to .05, unprotected least significant differences test). In Exp. 2, which compared naive yearlings with the experienced yearlings exposed as lambs in Exp. 1 the previous year, age of exposure did not influence consumption by yearling sheep following exposure; however, the number of months that had elapsed from the period of exposure varied from 0 to 13 among experimental groups and may have confounded results. Learning of forages appeared poor among nonruminant lambs; data were inconclusive concerning the efficiency of learning of lambs in the transition to ruminant digestion.

Extract The susceptibility of many trichostrongylid nematodes, particularly those inhabiting the abomasa of domestic ruminants, to inhibited parasitic develolpment is well known. In most cases development is arrested at a precise point for a given species, usually occurring shortly before or after a moult (Rogers and Sommerville, 1969). Of the abomasal parasites of sheep, inhibition in Haemonchus contortus and Ostertagia circumcincta occurs at the early fourth stage (Blitz and Gibbs, 1971; Sommerville, 1953, 1954) and in Trichostrongvlus axei at a more loosely defined “fourth” larval stage (Reid and Armour, 1972).

Studies were made of the effects of barley grass on young sheep. Up to 8 kg per lamb loss of weight gain during summer has been shown to be due (to barley grass seed damage. Seed in the eyes caused the most rapid growth check but irritation to nostrils, mouth, and skin all contributed. Lambs were affected far more than adult sheep and differences between breeds of sheep were sufficient to consider change of breed where barley grass was troublesome. The beneficial effects and disadvantages of herbicide conmtrol are discussed in relation to density of barley grass infestation.

The effects of various doses of theophylline on the plasma levels of calcium, inorganic phosphorus and magnesium were studied in sheep. The dose of 0.25 mg/kg/min. during 40 min. produced a hypocalcaemia, which was abolished by thyroidectomy. At a higher dose, 1.0 mg/kg/min., thyroidectomy reduced, but did not block, the hypocalcaemic effect of theophylline. Young sheep showed a greater calcium response than did adult ewes. The decrease in plasma calcium was in no case accompanied by hypophosphataemia. Plasma magnesium decreased in all groups after 1.0 mg/kg/min. and was not influenced by thyroidectomy. Theophylline increased the urinary excretion of calcium and magnesium. It is concluded that theophylline-induced hypocalcaemia in sheep is in part a result of increased calcitonin secretion but that also other mechanisms must be involved, e. g. a direct effect of theophylline on bone.

SUMMARY A field survey was undertaken between 1972–76 to reappraise the nature of the blowfly problem in New South Wales. For 2 years, 1972–1974, some 80,000 sheep were kept under observation and 12,481 strikes were reported, most due to Lucilia cuprina. Breech strike was still the basic problem but tail strike associated with scouring had become an important component where pastures have been improved. Breech strike was controlled at minimal cost by managerial practices such as docking tails the correct length—second joint-space palpable ventrally (midway down the vulval orifice in ewes) for radically mulesed lambs and the third joint-space (tip of vulva in ewes) for all other lambs-mulesing at lamb marking, mid-season crutching, determining the cause of scouring and applying the appropriate preventative or remedial measures. Thus the use of insecticides could be reserved for the control of body strike in young sheep in the odd wet years and poll strike in horned rams. Major outbreaks of body strike occurred in 1973/74. Body strike worried graziers most because of its unpredictability, sudden onset and scale, and only failing insecticides were available for control.

Extract The ability of a heavy pellet containing cobaltic oxide to release cobalt when lodged in the reticulo-rumen of the sheep was first described by Dewey et al. (1958). However, investigation has shown that, at least in some situations, treatment with cobaltic oxide pellets may have two disadvantages. First, pellets may acquire a deposit of calcium phosphate, thus tending to seal the pellet off from the, reticulo-rumen environment (Andrews et al., 1958; Dewey et al., 1958; Millar and Andrews, 1964). Secondly, some sheep may eventually lose their pellets by regurgitation (Millar and Andrews, 1964).

Extract Bowie is a disease of young sheep of some parts of the South Island, and occurs on restricted areas usually of the unimproved high country. The name has been derived from the most frequent and obvious abnormality, which is an outward bowing or bandiness of the fore legs. It is not, however, invariably the fore legs that are affected in this way, for in some lambs the hind legs are bandy, and in some the “bowing” is inwards instead of outwards. The condition has a superficial resemblance to the deformity in rickets in some species, and, indeed, was at one time thought to be rachitic in origin. Fitch (1954), however, showed that the disease is not a form of rickets because it occurs in a season of the year when solar irradiation should provide an adequate level of vitamin D, because blood calcium and phosphate levels in affected animals are within normal limits, and because there are fundamental histopathological differences between the two diseases.

Extract Regular anthelmintic treatment is often recommended as a routine procedure in the management of lambs and hoggets over the summer, autumn, and winter months. There is, however, little published information available on the effect of such a procedure on the health and productivity of sheep. It is clear that the effect will vary widely under different conditions of climate, management, plane of nutrition, and level of parasitic infestation.

SUMMARY: The program for reduction of human incidence of hydatid disease in Tasmania is described. The program has been in progress since 1965. It is based on intensive education, directed particularly at owners of infested dogs. Results up to 30th June, 1978, are presented. Prevalence in dogs has been reduced from 12.66% to 0.22%. Prevalence in young sheep has fallen from about 15% to 0.05%, and in aged sheep from over 50% to 3.4%. The incidence in man has fallen, although the extent of the fall is difficult to quantify because of the small number of human cases. It is suggested that new infestations of man may have ceased by about 1970. The implications of the Tasmanian program for other Australian states are briefly discussed.

The liveweight gain of young sheep set-stocked on browntop and 'Grasslands Ruanui' perennial ryegrass pastures was compared during the main periods of pasture growth over two years. During spring there was no difference between the two species, but in early summer, although flowering was suppressed by grazing, the higher liveweight gains on ryegrass were attributed to greater stem and stolen development and poorer leaf growth in the browntop pasture. In early autumn an outbreak of staggers in the ryegrass sheep apparently reduced liveweight gain relative to browntop where no staggers occurred. These differences are discussed in relation to the closer grazing of ryegrass than browntop at this time of year.