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1
Eady, SJ, PK O'Rourke e PT Connelly. "Comparison of wool production and reproductive rate of South Australian strain Merinos and locally bred Peppin Merinos in the semi-arid tropics of Queensland". Australian Journal of Experimental Agriculture 31, n. 6 (1991): 737. http://dx.doi.org/10.1071/ea9910737.
Testo completoAbstract (sommario):
Three experiments were conducted to provide information on the wool production and reproductive rates of different strains of Merino sheep, and on the role of heat tolerance in determining the productivity of sheep in north-western Queensland. The locally bred Peppin Merinos had a significantly (P<0.05) lower rectal temperature (RT) and respiratory rate (RR) under heat load than the South Australian (SA) strain Merinos. Place of birth of SA Merinos had no effect on their RT and RR. At 16 months of age the Peppin sheep produced significantly (P<0.05) less clean wool (1.55 v. 1.82 kg) and had significantly (P<0.05) lower liveweights (28.5 v. 31.6 kg) than the SA group reared in the same environment. Although differences between the groups were not always statistically significant, there was a trend for a consistent increase in wool production, fibre diameter and liveweight as the proportion of SA in the cross increased. The impact of these differences on proceeds from wool sales is discussed. At maturity the SA strain ewes were heavier (P<0.05) than their Peppin counterparts (48.4 v. 44.1 kg) and produced heavier (P<0.05) lambs at 6 weeks of age (7.0 v. 6.2 kg) and at weaning (13.9 v. 12.5 kg). Milk yield at 6 weeks post-lambing was significantly (P<0.05) greater for the SA sheep than the Peppin Merinos (303 v. 216 mL/day). Lamb survival from 6 weeks to 3 months was 64% for the SA Merinos and 45% for the Peppin Merinos, but this difference was not statistically significant. The SA strain Merinos produced more clean wool and heavier offspring than locally bred Peppin sheep and demonstrated a similar reproduction rate in the face of severe drought conditions.
2
Behrendt, Karl. "Price risk exposure of Australian Merinos – is it in the bloodline?" Animal Production Science 54, n. 9 (2014): 1317. http://dx.doi.org/10.1071/an14305.
Testo completoAbstract (sommario):
Sheep producers and their advisors utilise Australian Merino bloodline trial data to guide future sheep breeding objectives and ram selection. To adequately assess the economic outcomes from different bloodlines in the decision making process, there is a need to consider the impact of wool and sheep meat price risk. Using a steady-state wether flock model that accounts for the lifetime productivity of 268 reported Merino bloodlines and stochastic dependency in weekly wool and sheep meat prices from 28 June 2005 to 10 November 2011, gross incomes per dry sheep equivalent (GI/DSE) were calculated for a weekly time step. The analysis found that across all bloodlines and market price scenarios, GI/DSE ranged between AU$13.92 and AU$67.83, with an overall mean of AU$32.60. The individual means of bloodlines across the time series ranged from AU$37.46 to AU$25.19 GI/DSE. The coefficient of variation, used as the measure of relative risk for each bloodline, ranged from 0.24 to 0.30 with a mean of 0.25. The analysis showed that a bloodlines exposure to price risk has a curvilinear relationship to fibre diameter and fleece weight. The results from a risk-reward point of view indicate that the majority of Australian Merino bloodlines are risk-inefficient. This suggests Australian sheep producers have a significant opportunity to increase net returns and reduce price risk exposure by identifying and switching to more risk-efficient bloodlines.
3
LUSHNIKOV, V. P. "MEAT PRODUCTIVITY OF RAMS OBTAINED BY CROSSING VOLGOGRAD SHEEPS WITH RAMS OF DIFFERENT FOREIGN BREEDS". Sheep, goats, woolen business, n. 2 (2021): 23–25. http://dx.doi.org/10.26897/2074-0840-2021-2-23-25.
Testo completoAbstract (sommario):
The article presents the indicators of slaughter, morphological and chemical composition of lamb meat obtained from industrial crossing of Volgograd breed queens with sheep breeds: Poll Dorset, Australian meat merino, North Caucasian meat-wool, Suff olk, Ile-de-France and Merinoland.
4
Lakota, E. A. "Productivity of Stavropol sheep with Australian meat merino rocks in the Volga region". Agrarian science 322, n. 2 (febbraio 2019): 42–43. http://dx.doi.org/10.32634/0869-8155-2019-322-2-42-43.
Testo completo
5
Cottle, D. J., M. T. Harrison e A. Ghahramani. "Sheep greenhouse gas emission intensities under different management practices, climate zones and enterprise types". Animal Production Science 56, n. 3 (2016): 507. http://dx.doi.org/10.1071/an15327.
Testo completoAbstract (sommario):
Greenhouse gas emissions (GHG) from broadacre sheep farms constitute ~16% of Australia’s total livestock emissions. To study the diversity of Australian sheep farming enterprises a combination of modelling packages was used to calculate GHG emissions from three sheep enterprises (Merino ewe production for wool and meat, Merino-cross ewes with an emphasis on lamb production, and Merino wethers for fine wool production) at 28 sites across eight climate zones in southern Australia. GHG emissions per ha, per dry sheep equivalents and emissions intensity (EI) per tonne of clean wool or liveweight sold under different pasture management or animal breeding options (that had been previously determined in interviews with farmers) were assessed relative to baseline farms in each zone (‘Nil’ option). Increasing soil phosphorus fertility or sowing 40% of the farm area to lucerne resulted in the smallest and largest changes in GHG/dry sheep equivalents, respectively (–66%, 113%), though both of these options had little influence on EI for either clean wool or liveweight sold. Breeding ewes with greater body size or genotypes with higher fleece weight resulted in 11% and 9% reductions, respectively, in EI. Enterprises specialising in lamb production (crossbred ewes) had 89% lower EI than enterprises specialising in fine wool production (Merino wethers). Thus, sheep producers aiming for lower EI could focus more on liveweight turnoff than wool production. Emissions intensities were typically highest in cool temperate regions with high rainfall and lowest in semiarid and arid regions with low aboveground net primary productivity. Overall, animal breeding options reduced EI more than feedbase interventions.
6
Lakota, E. A., e M. V. Zabelina. "An effective type of merino in the Volga region by the method of intrabreed selection". Agrarian science, n. 7-8 (24 settembre 2021): 24–27. http://dx.doi.org/10.32634/0869-8155-2021-351-7-8-24-27.
Testo completoAbstract (sommario):
The article presents experimental data on the use of intrabreed selection in order to create the most effective productive type of sheep of the Stavropol fine-wool breed. In the zone of the dry steppe of the Volga region the sheep of the Stavropol breed were improved by the meat merino of the Australian selection. Scientific and experimental research was carried out in JSC “New Life” ofNovouzensky district of the Saratov region. The crossbreeds obtained during the step-by-step crossing of Stavropol sheep with tup-producers of Australian meat merino with 1/8-blood content according to AMM by eye-measuring the degree of severity of wool and meat productivity were distributed according to productive indicators (live weight, wool shearing) to the corresponding specific types of productivity. The first group — the uterus of the wool productive type; the second — wool-meat, the third — meat-wool. Each group of sheep was assigned to tuh of meat-wool productive type. The offspring were obtained according to the selection of parental pairs: father x mother. At birth, the M-W x M-W ewe hoggs had an advantage over the W x M-Wanimals in terms of live weight by 7.47%, and over the M-W x M-W — by 1.7%. After weaning at 4.5 months, the live weight of all young animals decreased slightly. In 13.5 months, the superiority of group III over group I and II was 9.3%, 4.6%. In terms of cutting physical wool, group II yarks outperformed group I and III by 1.91 and 3.45%, while their advantage in pure wool was 13.6 and 4.11%. The longest coat was characterized by the young animals of group I, the stronger coat was in the young animals of group III. In the structure of fine-wooled sheep of the Stavropol breed of the Volga population three productive types were distinguished, which differ from each other in terms of productive indicators: wool, wool-meat and meat-wool. At the same time sheep of the Stavropol breed, bred in the dry steppe of the Volga region, to a greater extent deviate towards the wool-meat productive type, such merinos of the combined direction in the conditions of the modern economic situation are most demanded and profitable.
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Ponnampalam, E. N., D. L. Hopkins, F. R. Dunshea, D. W. Pethick, K. L. Butler e R. D. Warner. "Genotype and age effects on sheep meat production. 4. Carcass composition predicted by dual energy X-ray absorptiometry". Australian Journal of Experimental Agriculture 47, n. 10 (2007): 1172. http://dx.doi.org/10.1071/ea07008.
Testo completoAbstract (sommario):
This study compares the carcass composition of different genotypes of Australian sheep slaughtered at four ages (110, 236, 412 and 662 days of age, or 4, 8, 14 and 22 months of age). The genotypes used were Poll Dorsetgrowth × Border Leicester Merino (PDg × BLM), Poll Dorsetgrowth × Merino (PDg × M), Poll Dorsetmuscling × Merino (PDm × M), Merino × Merino (M × M) and Border Leicester × Merino (BL × M). Approximately 150 mixed sex animals were slaughtered at each age and the right sides (half carcass) were scanned by dual energy X-ray absorptiometry (DXA) for chemical lean, fat and bone mineral percentages of the carcass. Carcass lean percentage decreased (P < 0.001) across sire groups from Merino to Poll Dorset to Border Leicester at each age, while fatness increased (P < 0.001) in the opposite direction. With age, the magnitude of difference between genotypes for fatness became greater. There was a marked increase (P < 0.01) in ash mineral percentages in M × M and PDg × M genotypes relative to other genotypes in the 14- and 22-month groups. There were no differences (P > 0.1) between PDg × M and PDm × M in either chemical lean or fat percentages at any age but ash mineral percentage was higher in the PDg × M genotype at older ages (P < 0.05). This in turn led to differences in chemical lean : ash mineral content at later ages between PDg × M and PDm × M. Wethers had higher chemical lean (P < 0.05) and lower fat (P < 0.05) percentages in the carcass than ewes at all ages but ash mineral and chemical lean : ash mineral content did not differ between sexes. It was clear that the level of chemical lean or fat or ash mineral composition reached by some genotypes at one age was equivalent to that reached by other genotypes at the next measurement age. Those genotypes that reach a specification at younger ages will be more productive for meat production. Purebred Merino genetics will always be less productive in terms of carcass weight and muscle related productive traits (loin weight, semitendinosus muscle weight, eye muscle area) than BL and PD genetics, but the relative productivity of PD and BL genetics will depend on the traits used in the specification [see also Ponnampalam EN, Hopkins DL, Butler KL, Dunshea FR, Warner RD (2007) Genotype and age effects on sheep meat production. 2. Carcass quality traits. Australian Journal of Experimental Agriculure 47, 1147–1154]. The results suggest that selection for muscling had a greater impact on reducing ash mineral content associated with bone mineral mass than on increasing lean mass in the carcass.
8
Aboneev, Vasily, Dmitry Aboneev, Ekaterina Aboneeva, Safarbi Kazanchev e Dastanbek Baimukanov. "Results of using different breed studs in commercial fine wool sheep breeding". E3S Web of Conferences 262 (2021): 02016. http://dx.doi.org/10.1051/e3sconf/202126202016.
Testo completoAbstract (sommario):
This work presents the material of research and production experiments on the crossing of stud rams of the North Caucasian meat and wool breed and Australian meat merino with fine wool ewes of a commercial herd. It is identified that the use of North Caucasian rams on fine wool ewes serves to increase the fertilizing ability and milk production of the breeding stock, to increase viability and resistance of young animals, as confirmed by the best morphometrical differences of crossbred offspring placentas. Crossbred offspring from semi-fine wool rams had a large live weight at birth at 21 days and at 4 months of age. The use of Australian producers did not have a significant effect on the above indicators of economically useful traits in comparison with purebred breeding.
9
Li, G. D., K. R. Helyar, M. K. Conyers, L. J. C. Castleman, R. P. Fisher, G. J. Poile, C. J. Lisle, B. R. Cullis e P. D. Cregan. "Pasture and sheep responses to lime application in a grazing experiment in a high-rainfall area, south-eastern Australia. II. Liveweight gain and wool production". Australian Journal of Agricultural Research 57, n. 10 (2006): 1057. http://dx.doi.org/10.1071/ar05299.
Testo completoAbstract (sommario):
‘Managing Acid Soils Through Efficient Rotations (MASTER)’ is a long-term pasture–crop rotation experiment commenced in 1992. One of the objectives was to demonstrate the extent of crop, pasture, and animal responses to lime application on a typical acidic soil in the 500–800 mm rainfall zone of south-eastern Australia. Two types of pastures (perennial v. annual pastures) with or without lime application were established in 1992. Fifteen- to eighteen-month-old Merino hoggets were used as test animals and were changed annually. This paper reports the results of sheep responses to liming from the 4 continuous pasture treatments over 6 years from 1992 to 1997. The stocking rate was the same on all plots within a treatment during each rotation period, but was varied between treatments based on the pasture availability and sheep body condition. The most important findings from this study are that the limed treatments carried 29% and 27% more stock (up to 4 DSE/ha) than the unlimed treatments for perennial and annual pastures, respectively. As a result, the limed perennial pastures produced 27% more liveweight gain (62 kg/ha.year) and 28% more greasy wool (13 kg/ha.year) than unlimed perennial pastures, whereas the limed annual pastures produced 34% more liveweight gain (77 kg/ha.year) and 24% more greasy wool (11 kg/ha.year) than unlimed annual pastures. The significant responses to lime in liveweight and wool production were detected from the second growing season after the pastures were established. The increased sheep productivity on the limed treatment was due to a combination of increased pasture production and improved pasture quality. Perennial pastures showed a slight advantage in wool production, but not in liveweight gain. However, the seasonal variation of liveweight was greater on annual pastures than on perennial pastures. The larger variation in liveweight change could lead to more adverse effects on wool quality especially at high grazing pressures. Grazing management can be used to manipulate pasture and animal productivity to increase profits from lime use.
10
Ferguson, M. B., J. M. Young, G. A. Kearney, G. E. Gardner, I. R. D. Robertson e A. N. Thompson. "The value of genetic fatness in Merino ewes differs with production system and environment". Animal Production Science 50, n. 12 (2010): 1011. http://dx.doi.org/10.1071/an10130.
Testo completoAbstract (sommario):
Selection against fatness in the Australian sheep industry has been a priority, but defining the true value of fat requires an understanding of the effects it has on both the value of lamb carcasses and on sheep productivity. A Merino flock with 10 years of reproduction data was used to analyse the correlation between breeding values for fatness at yearling age (YFAT) and the number of lambs born per ewe mated (NLB). In 2 production years, NLB was related (P < 0.01) to YFAT resulting in an extra 14 or 24.5 lambs born per 100 ewes mated per mm of YFAT. Based on these relationships, bio-economic modelling was used to assess the whole-farm value of YFAT for different sheep production systems and for years representing a low, medium and high response of NLB to YFAT. The changes in whole-farm profitability for a 1-mm increase in YFAT varied from $1000 (2%) for a wool enterprise with a low response up to $44 000 (25%) for a lamb enterprise with a high response. Appropriate carcass value discounts for higher YFAT were investigated but were not evident because of the small change in GR fat depth associated with the range of YFAT investigated. In most years there is no impact of YFAT on NLB and therefore profitability, yet in years where Merino ewes with higher YFAT produce higher NLB, ewes with an extra 1 mm of YFAT will be up to 25% more profitable. Therefore, care is required in determining the appropriate selection pressure to be placed on YFAT in Merino selection.
11
Denney, GD. "Effect of pre-weaning farm environment on adult wool production of Merino sheep". Australian Journal of Experimental Agriculture 30, n. 1 (1990): 17. http://dx.doi.org/10.1071/ea9900017.
Testo completoAbstract (sommario):
The influence of pre-weaning environment on the adult productivity of medium Peppin Merino sheep has been examined in field experiments. In 1983 and 1984 groups of pregnant ewes and. subsequently, their lambs were run with breeding flocks on farms located over the Central Tablelands and Central Western Slopes of New South Wales. After weaning, each year's progeny grazed as a single flock at Condobolin on the Central Western Slopes, thus allowing the sheep equal nutritional opportunity in post-weaning and adult life. Differences in the progeny's liveweight and wool production could be attributed to the effects of the different environmental conditions experienced before they were weaned. Birth weight and lamb growth rates were affected (P<0.001) by early environment. At weaning, mean group liveweights covered a range of 6.9 kg in 1983 and 7.8 kg in 1984. In both years the proportion of the phenotypic variation of liveweight due to pre-weaning environment fell from approximately 0.35 at weaning to 0.15 (P<0.001) at 12 months of age, but the proportion was not significantly different from zero when the progeny were 24 and 36 months of age. Pre-weaning environment affected the production of greasy wool (P<0.001) over the progeny's first year of life. However, among the 1983 progeny no differences in wool production were observed at 24 and 36 months of age. With 1984 progeny no differences occurred at 24 months of age or, when the wool weights were adjusted to a common liveweight by covariance, at 36 months of age. Yield, fibre diameter and staple length were not affected by pie-weaning environment when measured at 24 and 36 months, and there were no differences between groups in the ratio of secondary to primary wool follicles or in wool follicle density at 36 months of age. It is concluded that the adult productivity of Merino sheep is unlikely to be permanently reduced by poor pre-weaning environmental conditions on farms but overall flock productivity will be reduced if fewer weaners survive.
12
Eady, SJ, DA Pritchard e PK O'Rourke. "Effects of genotype and environment on wool production of Merinos at pasture at two locations in semi-arid tropical Queensland". Australian Journal of Experimental Agriculture 30, n. 6 (1990): 735. http://dx.doi.org/10.1071/ea9900735.
Testo completoAbstract (sommario):
The problem of low wool production in central- western and north- western Queensland led to a study of the relative wool production of different genotypes of Merino sheep in these 2 regions. A number of the bloodlines of sheep introduced to central western and north-western Queensland attained a higher mature liveweight (P<0.01) and produced more wool (P<0.05) than the locally bred sheep. Annual wool production was closely related to mature liveweight, and the strong wool South Australian Merinos were consistently the heaviest and produced the most wool. Ranking on fleece characteristics and liveweight was consistent for both locations. Under severe nutritional stress, the sheep introduced to north-western Queensland showed a significantly (P<0.05) greater drop in tensile strength of their wool than locally bred sheep. There was a significant difference (P<0.05) between productivity levels of the sheep at each location, with the environment in central-western Queensland being more suited to wool production. The results of this experiment suggest that some bloodlines of Merinos offer the potential to improve the wool production of sheep bred in central- western and northwestern Queensland; however, the effect of rearing environment may also be important.
13
Revell, D. K., H. C. Norman, P. E. Vercoe, N. Phillips, A. Toovey, S. Bickell, E. Hulm, S. Hughes e J. Emms. "Australian perennial shrub species add value to the feed base of grazing livestock in low- to medium-rainfall zones". Animal Production Science 53, n. 11 (2013): 1221. http://dx.doi.org/10.1071/an13238.
Testo completoAbstract (sommario):
Australian native perennial shrubs that are adapted to drought and infertile soils contribute nutrients to grazing systems that would otherwise support limited ruminant productivity. In this study, we report the nutritive value of 39 Australian shrub species of the genera Atriplex, Rhagodia, Maireana, Chenopodium, Enchylaena, Acacia, Eremophila, and Kennedia. Edible foliage was sampled in winter and summer, and there was little difference in nutritive value between seasons. The in vitro organic matter digestibility of most shrub species was 40–70%. Most species contained medium to high levels of crude protein (12–22% of dry matter, DM) and high concentrations of sulfur (2–8 g/kg DM). In an 8-week grazing experiment in which Merino wethers grazed a ‘shrub system’ containing four shrub species and a sown inter-row of annual pasture, the sheep gained weight during autumn without supplementary feeding. By comparison, sheep fed senesced volunteer pasture and supplementary cereal grain only maintained weight. The forage shrubs provided up to 50% of the total DM intake of sheep grazing the ‘shrub system’ and made a modest contribution to the digestible energy intake of the animals and a large contribution to their crude protein and mineral intake. Considering the timely and predictable provision of limiting nutrients and benefits such as gut health and the provision of shade and shelter, we suggest that Australian shrub species can make a valuable addition to the feed base of low- to medium-rainfall zones in southern Australia.
14
Hrymak, K. "The sexual activity of the ram-sires, depending on their mode of use". Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 21, n. 91 (6 novembre 2019): 29–32. http://dx.doi.org/10.32718/nvlvet-a9105.
Testo completoAbstract (sommario):
Literary data are presented and their analysis is conducted regarding the mode of use of ram-sires and their effect on sexual activity and sperm productivity. The results of research of scientists with recommendations of optimal modes of use of fetuses for semen production and its cryopreservation in non-pairing and steaming periods are presented. According to the results of the analysis of many researchers, the activity of the sexual reflexes of the rams in the spring and summer decreases by 1.4 times compared to the winter. At the same time quantitative indicators of sperm productivity decrease. However, M.M. Aibazov (1987) experimentally confirmed that sheep-breeders of the Caucasian fine-breed and Australian merenos breed exhibit high sexual activity and produce sperm of satisfactory quality in all seasons. Similar results were obtained by British researchers in the study of sexual activity and sperm productivity of ram-sires of British breeds. A.A. Ivanov (1987) indicates the regime of use of ram sires, for five years with obtaining and subsequent freezing in the unpaired period 6 ejaculates (2 doublets 3 times) per week and in the breeding season 10 ejaculates (2 doublets 5 times) week. P.P. Kundyshev (2004) considers it possible and proposes to obtain from the breeding rams for cryopreservation and storage during the year, both unpaired and steaming periods, with daily ejaculate production. This mode, according to the author, provides a sufficiently high fertility sperm up to 50.3 percent. In the study of sexual activity and sperm productivity of ram-sires of different breeds, including the North Caucasian meat-wool, jalgin merino, Soviet merino, maniche merino, Russian meat merino, Edelbaev, polldore P.P. Mammoth and others. (2018) found that the most active were the rams of the Edinburgh breed, which took 22 seconds. ejaculate secretion, and the slowest texel breeders, which took 39 seconds to ejaculate. The rams of the other breeds listed above spent 25 to 34 seconds to ejaculate. In addition, rams of Texel breed produced the lowest activity sperm, and therefore only 19 sperm were frozen from one ejaculate, with an average of 20 to 26 sperm species tested.
15
Sawyer, Gregory, Dylan Russell Fox e Edward Narayan. "Pre- and post-partum variation in wool cortisol and wool micron in Australian Merino ewe sheep (Ovis aries)". PeerJ 9 (27 aprile 2021): e11288. http://dx.doi.org/10.7717/peerj.11288.
Testo completoAbstract (sommario):
An individual merino sheep’s output of wool production is influenced by synergistic interactions of sheep genetics, climate, farm management, and nutrition available to the whole flock. The price paid to the producer for this wool commodity is determined via numerous tested parameters and /or subjective appraisal of the raw greasy wool. This research investigated the level of variation in wool cortisol (a physiological stress biomarker) and wool micron (MIC) in Merino ewes (Ovis aries), pre-partum and post-lambing (lactation/lambs at foot), using maiden ewe (n = 38) managed in an outdoor paddock in a commercial farm. The key findings of this study are; (1) wool quality indicators showed a significant variation between pre- and post- parturition including significant reduction in MIC and (2) there was a negative correlation between wool cortisol levels and wool micron pre-parturition (rs = − 0.179, p < 0.05). This relationship between wool cortisol and wool micron was positive (rs = + 0.29, p < 0.05) during post-parturition suggesting that ewes with lambs at foot ended up with finer wool (reduction in fibre diameter) but they also maintained high levels of wool cortisol. Furthermore, the comfort factor, curvature, standard deviation and spin fineness of the wool were also significantly reduced post-parturition. The results of this study show that metabolic resources partitioning in ewe associated with pregnancy and lambing can result in a reduction in wool quality indices. The activity of the HPA-axis is attenuated during late gestation and parturition as a maternal adaptation; however, the results of our study show that wool cortisol remained similar between pre- and post- lambing. This result indicates that environmental stressors that may have been operating on farm (e.g., cold winter period) could influence on maternal physiological stress response however the exact level of influence of environment conditions on ewe stress levels and productivity traits (e.g., lambing success and wool quality) warrants further investigation. In conclusion, the use of top-knot wool sampling in combination with wool cortisol analysis provides researchers with a convenient method to quantify wool quality and physiological stress simultaneously under commercial sheep production.
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Norton, BW, FT O'Grady e JW Hales. "Grazing management studies with Australian cashmere goats. 2. Effect of stocking rate on the liveweight gain of sheep and goats grazing an oats-rye grass pasture". Australian Journal of Experimental Agriculture 30, n. 6 (1990): 777. http://dx.doi.org/10.1071/ea9900777.
Testo completoAbstract (sommario):
Australian cashmere goats and Border Leicester x Merino sheep grazing an oats-rye grass pasture were used to study the effects of stocking rate (20, 40, 60 animals/ha) on growth, intestinal parasite burdens and haematology of the 2 species and on the persistence and productivity of the crop grazed. Goats and sheep were either grazed alone or together over a 12-week period to determine the interaction between the species. Liveweight gain decreased with both stocking rate and time on experiment. At the highest stocking rate all animals lost weight between weeks 9 and 12. During the first 9 weeks of grazing, sheep had significantly (P<0.05) higher liveweight gains than goats at all stocking rates; but the rate of decline in liveweight gain with increased stocking rate was similar in both species, whether they were grazed alone or together. Mean values for sheep were 161, 133 and 105 g/day, and for goats 101, 84 and 59 g/day at stocking rates of 20, 40 and 60 animals/ha. Under the same drenching regime, goats were more severely infested by intestinal parasites than sheep as indicated by significantly (P<0.05) higher concentrations of parasite eggs in faeces and lower packed cell volumes and haemoglobin concentrations in blood. Oats was the major contributor to green feed available at all stocking rates, although rye grass yields increased in the later stages of the trial, particularly in high stocking rate paddocks. At the end of the trial, high yields of oat stem remained in the paddocks grazed by goats and goats plus sheep, suggesting that sheep grazed both leaf and stem but goats selectively grazed oat leaf. The availability of green leaf (oat + rye grass) per animal was closely related to liveweight gain in any period, although these relationships were different for sheep and goats.
17
Paganoni, B. L., C. M. Oldham, M. B. Ferguson, A. N. Thompson, P. E. Vercoe e D. G. Gordon. "Ewe nutrition during pregnancy and birthweight of lambs has minimal impact on fat and eye muscle depth in Merino progeny". Animal Production Science 53, n. 6 (2013): 509. http://dx.doi.org/10.1071/an12266.
Testo completoAbstract (sommario):
The hypothesis tested in this experiment was that Merino lambs with lower birthweights, due to poor ewe nutrition during pregnancy, would have more fat and less muscle than Merino lambs with higher birthweights. At two sites (Victoria and Western Australia) in each of 2 years, a wide range in the liveweight profiles of ewes was generated during pregnancy and lactation by varying the amount of supplements fed and feed on offer grazed. Progeny had fat and muscle depth at the C-site measured at various ages from 8 to 28 months of age. Across the four experiments, there were differences of 0.5 kg in birthweights and 8 kg in weaning weights between extreme treatments. The effects on the depth of fat and muscle were very small with fat depth increasing by 0.1–0.2 mm (5–7%) and muscle depth increasing by 0.2–0.7 mm (1–3%) when birthweights decreased by 1 kg. The effects of birthweight on fat depth are consistent with our hypothesis whereas the effects of birthweight on muscle depth are in contrast to our hypothesis. Nevertheless, the impacts of birthweight on the depth of fat and muscle measured at the C-site of progeny from Merino ewes, is unlikely to be of any commercial significance within the range of nutritional scenarios during pregnancy and lactation that are likely to be experienced within the Australian sheep industry.
18
Hodge, Marnie J., Sara de las Heras-Saldana, Sally J. Rindfleish, Cyril P. Stephen e Sameer D. Pant. "Characterization of Breed Specific Differences in Spermatozoal Transcriptomes of Sheep in Australia". Genes 12, n. 2 (30 gennaio 2021): 203. http://dx.doi.org/10.3390/genes12020203.
Testo completoAbstract (sommario):
Reduced reproductive efficiency results in economic losses to the Australian sheep industry. Reproductive success, particularly after artificial insemination, is dependent on a number of contributing factors on both ewe and ram sides. Despite considerable emphasis placed on characterising ewe side contributions, little emphasis has been placed on characterising ram side contributions to conception success. Over 14,000 transcripts are in spermatozoa of other species, which are transferred to the ova on fertilisation. These transcripts conceivably influence early embryonic development and whether conception is successful. Semen was collected (n = 45) across three breeds; Merino, Dohne, and Poll Dorset. Following collection, each ejaculate was split in two; an aliquot was assessed utilising Computer Assisted Semen Analysis (CASA) and the remaining was utilised for RNA extraction and subsequent next-generation sequencing. Overall, 754 differentially expressed genes were identified in breed contrasts and contrast between ejaculates of different quality. Downstream analysis indicated that these genes could play significant roles in a broad range of physiological functions, including maintenance of spermatogenesis, fertilisation, conception, embryonic development, and offspring production performance. Overall results provide evidence that the spermatozoal transcriptome could be a crucial contributing factor in improving reproductive performance as well as in the overall productivity and profitability of sheep industries.
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Bell, A. W. "Prenatal programming of postnatal productivity and health of livestock: a brief review". Australian Journal of Experimental Agriculture 46, n. 7 (2006): 725. http://dx.doi.org/10.1071/ea06006.
Testo completoAbstract (sommario):
Human epidemiological evidence has suggested that metabolic perturbations during fetal life may increase predisposition to cardiovascular disease, type 2 diabetes and obesity in later life. A growing number of controlled experiments on sheep and other large animal species are adding to the already large body of experimental evidence from rat studies in supporting the ‘fetal origins’ hypothesis. Of particular practical relevance are findings that maternal undernutrition in late pregnancy can predispose lambs to glucose intolerance and increased adiposity in early adulthood. This effect may be exacerbated by high energy intakes and limited capacity for muscle growth in undernourished or growth-retarded lambs during early postnatal life. Recent Australian studies have demonstrated the effects of prenatal nutrition on postnatal growth and meat production in beef cattle, and on quantity and quality of wool production in sheep.
20
Bencini, R., T. W. Knight e P. E. Hartmann. "Secretion of milk and milk components in sheep". Australian Journal of Experimental Agriculture 43, n. 6 (2003): 529. http://dx.doi.org/10.1071/ea02092.
Testo completoAbstract (sommario):
The effect of milking intervals of 4–20 h and of milking frequencies of 1–6 times a day on the rate of secretion of milk and milk components was determined in 2 breeds of sheep unselected for dairy production, the Australian Merino and the New Zealand Poll Dorset. The rate of milk secretion was greater after short intervals and after increased milking frequencies, indicating that in sheep the rate of milk secretion in the short term is regulated by a local feedback mechanism. After short intervals between milkings, the fat concentration in the milk was higher (99.5 ± 6.21 g/kg) and the protein concentration was lower (about 65 ± 2.89 g/kg) than after long intervals between milkings. This was not due to the presence of residual milk left in the mammary glands as subsequent experiments gave similar results when the residual milk was removed with the aid of oxytocin. We obtained similar responses if ewes were exposed to a series of 4 consecutive milkings to remove possible carry-over effects of the previous interval and achieve a constant volume of residual milk. We concluded that in sheep the rate of secretion of fat decreases while that of protein increases with time after milking and that the synthesis of fat and protein are controlled by at least 2 different mechanisms. This might be due to the fact that, unlike dairy cows and goats, sheep have not been subjected to selective pressure for dairy production.
21
Warner, R. D., D. W. Pethick, P. L. Greenwood, E. N. Ponnampalam, R. G. Banks e D. L. Hopkins. "Unravelling the complex interactions between genetics, animal age and nutrition as they impact on tissue deposition, muscle characteristics and quality of Australian sheep meat". Australian Journal of Experimental Agriculture 47, n. 10 (2007): 1229. http://dx.doi.org/10.1071/ea07229.
Testo completoAbstract (sommario):
The combined effects of age and genetics and Poll Dorset sire and growth path were studied in two separate experiments (n = 595 and 627, respectively). In the first experiment, containing genotype crosses typically used in Australia (Merino, Poll Dorset, Border Leicester) and sires selected for growth or muscling, sheep were slaughtered at 4, 8, 14 and 22 months. The second experiment used Poll Dorset sires selected for high muscling, fat or growth with progeny having two levels of nutrition postweaning. Border Leicesters expressed higher levels of carcass fat percentage and intramuscular fat and produced the heaviest carcass. Merinos had the lowest subcutaneous fat depth and highest carcass lean percentage when compared at the same age. The progeny of Poll Dorset sires selected for high muscling (PDm) expressed a shift toward glycolytic fibres relative to those from Merino sires, and PDm sires produced progeny with reduced spine and limb length and higher carcass muscle : mineral ratios, suggesting skeletal stunting. Genotype meat quality differences were minimal except that PDm sire topsides were tougher and Merinos produced higher pH meat. With age (4–22 months), lambs became heavier and fatter, fibres shifted towards oxidative and away from glycolytic, muscle myoglobin increased, the meat became darker and redder and tenderness declined. Early weaning had no effect on the time to reach slaughter weight, provided nutrition was not restricted. The sire genetics influence on the carcass composition far outweighed the effect of nutrition postweaning. Lambs on a restricted diet tended to have less acceptable meat quality but this was not evident in lambs from sires selected for high fatness. Sensory tenderness was improved and intramuscular fat was higher in lamb progeny from sires selected for high fatness.
22
Entwistle, K. W., L. J. Cummins, M. A. Hillard, J. E. Kinder, T. O'Shea, L. R. Piper, J. Thimonier e J. F. Wilkins. "Bernard Michael Bindon — reproductive physiologist, animal scientist, research leader". Australian Journal of Experimental Agriculture 46, n. 2 (2006): i. http://dx.doi.org/10.1071/ea05222.
Testo completoAbstract (sommario):
This paper is a foreword to a series of papers commissioned on ‘the impact of science on the beef industry’, where the Beef CRC-related collaborative scientific work of Professor Bernard Michael Bindon will be reviewed. These papers will be presented in March 2006, as part of a ‘festschrift’ to recognise his wider contributions to the Australian livestock industries for over 40 years. Bindon’s career involved basic and applied research in many areas of reproductive physiology, genetics, immunology, nutrition, meat science and more recently genomics, in both sheep and cattle. Together with his collaborators, he made large contributions to animal science by improving the knowledge of mechanisms regulating reproductive functions and in elucidating the physiology and genetics of high fecundity livestock. His collaborative studies with many colleagues of the reproductive biology and genetics of the Booroola Merino were amongst the most extensive ever conducted on domestic livestock. He was instrumental in the development of immunological techniques to control ovulation rate and in examining the application of these and other techniques to increase beef cattle reproductive output. This paper tracks his investigations and achievements both within Australia and internationally. In the later stages of his career he was the major influence in attracting a large investment in Cooperative Research Centres for the Australian cattle industry, in which he directed a multi-disciplinary approach to investigate, develop and disseminate science and technology to improve commercial cattle productivity.
23
Thompson, A. N., M. B. Ferguson, A. J. D. Campbell, D. J. Gordon, G. A. Kearney, C. M. Oldham e B. L. Paganoni. "Improving the nutrition of Merino ewes during pregnancy and lactation increases weaning weight and survival of progeny but does not affect their mature size". Animal Production Science 51, n. 9 (2011): 784. http://dx.doi.org/10.1071/an09139.
Testo completoAbstract (sommario):
Lamb growth to weaning, and during the period immediately following weaning, influences post-weaning mortality and may affect mature size. The hypothesis tested in the experiments reported in this paper was that changes in the maternal liveweight of Merino ewes during pregnancy and lactation could predict the weight at weaning, post-weaning survival and mature size of their progeny. At two sites (Vic. and WA) in each of two years, a wide range in the liveweight profiles of ewes was generated during pregnancy and lactation by varying the amount of supplements fed and feed on offer grazed. Across the four experiments this resulted in progeny weights ranging from 13.8 to 28.3 kg just before weaning. Lamb growth was primarily related to the amount of feed on offer during lactation, but was also related to the liveweight change of the ewe during pregnancy. These relationships were consistent in both experiments at each site. Weaning weight was strongly associated with post-weaning survival at the Vic. site. Survival rates decreased significantly when weaning weights were below 20 kg. These results indicate that management of ewe and lamb nutrition to maximise growth of lambs before weaning and growing weaners at 30 g/day or more after weaning are important for optimal post-weaning survival. The findings also suggest that the mature size of offspring is unlikely to be adversely affected by pre-weaning nutrition within the range of nutritional scenarios during pregnancy and lactation that are likely to be experienced within the Australian sheep industry.
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Kirkegaard, J. A., S. J. Sprague, H. Dove, W. M. Kelman, S. J. Marcroft, A. Lieschke, G. N. Howe e J. M. Graham. "Dual-purpose canola—a new opportunity in mixed farming systems". Australian Journal of Agricultural Research 59, n. 4 (2008): 291. http://dx.doi.org/10.1071/ar07285.
Testo completoAbstract (sommario):
The term dual-purpose canola describes the use of a canola crop for forage before seed production. It could potentially provide a profitable and flexible break-crop option for mixed farms, but there have been no studies to test the concept in Australia. We investigated the feasibility of using canola in this way in field experiments near Canberra, Australia, from 2004 to 2006, using European winter and mid–late maturing Australian spring canola varieties. Winter varieties sown from early March to mid-April produced 2.5–5.0 t/ha of biomass providing 0.3–3.5 t/ha of high-quality forage grazed by sheep in winter. The spring varieties produced similar amounts of vegetative biomass from April sowing but were unsuited to the earlier March sowing as they flowered in early winter and did not recover from grazing. The canola forage was readily eaten by sheep; alkane-based estimates of diet composition indicated that >85% of the organic matter intake consisted of canola. Canola forage was also highly digestible (86–88%) and Merino hoggets grew at 210 g/day from a dry matter intake of 1530 g DM/day. The canola generally recovered well when grazed in winter before bud elongation. Delays in flowering associated with heavy grazing ranged from 0 to 4 days when grazed before buds were visible, to 28 days if the crop had commenced flowering. Significant delays in flowering (>14 days) associated with winter grazing did not reduce seed yield or oil content when favourable spring conditions allowed compensatory growth. Yield loss was observed when winter and spring conditions were unfavourable for compensatory growth, or if grazing continued too late into spring (late September) irrespective of seasonal conditions. The yield loss was more than offset by the value of the grazed forage and the mean gross margin for dual-purpose canola over the four experiments was $240 to $500 higher than for grain-only canola depending on the value assumed for the forage. The study indicates there is considerable scope to capture value from grazing early-sown canola crops during winter without significant, uneconomic trade-offs with seed yield. Further investigations in other medium to high rainfall environments in southern Australia are warranted.
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McCormick, J. I., J. W. Paulet, L. W. Bell, M. Seymour, M. P. Ryan e S. R. McGrath. "Dual-purpose crops: the potential to increase cattle liveweight gains in winter across southern Australia". Animal Production Science 61, n. 11 (2021): 1189. http://dx.doi.org/10.1071/an19231.
Testo completoAbstract (sommario):
Context Dual-purpose wheat (Triticum aestivum L.) and canola (Brassica napus L.) crops have been extensively researched for grazing in Australian farming systems, with a focus on grazing by sheep. In some regions, dual-purpose crops have been grazed by cattle, but there have been reports of animal health problems. Aims This paper sought to collate all known experiments conducted throughout Australia of cattle grazing dual-purpose crops, in order to evaluate grazing management options for cattle on dual-purpose crops that result in high growth rates and good animal health outcomes. Methods There were six experiments. In Expts 1–3, cattle were grazed on wheat crops with and without available mineral supplementation of NaCl and MgO in a 1:1 ratio. In Expt 3, lime was also added to the mineral mix. In Expts 4 and 5, dual-purpose crops were grazed in combination with annual pastures to determine whether strategic use of dual-purpose crops could increase whole farm livestock productivity. In Expt 6, cattle were introduced to dual-purpose canola with different periods of adaptation (0, 4 and 7 days). Liveweight gain was monitored regularly to assess differences between adaptation treatments. Key results Liveweight gain was increased by 0–27% when cattle grazing high quality, dual-purpose wheat were provided with mineral supplement. Cattle had an initial lag in growth rate when introduced to dual-purpose canola for grazing and this was not affected by the adaptation strategy used. Cattle that experienced a shorter adaptation period achieved higher weight gains more quickly. After the lag phase, average daily gain (ADG) was ≥2 kg/head.day, with an ADG over the entire grazing period for all treatments of 1.75 kg/head.day. The effect on the farm system was determined by extending the length of the grazing period on the dual-purpose crops. Grazing periods of shorter duration did not increase overall liveweight gains compared with grazing only pasture, whereas extending the period of dual-purpose crop grazing resulted in increased cattle weights. Conclusions Cattle benefit from the addition of mineral supplements when grazing a dual-purpose wheat crop, with a response similar to that previously demonstrated in sheep. Cattle can safely graze dual-purpose canola and achieve high ADG. Inclusion of dual-purpose crops can improve overall cattle performance in the farming system. Implications The potential area for production of dual-purpose crops within the Australian mixed farming zone is large and there may be insufficient livestock numbers within the zone to utilise the potential forage production. Cattle from other regions could be introduced during autumn and winter to realise this large forage potential during a period that is commonly a feed deficit on grazing-only properties. Estimates suggest that up to two million young cattle could be supported for 60 days, increasing liveweight by 90 kg/head.
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Hantzopoulou, Georgia-Constantina, Gregory Sawyer, Alan Tilbrook e Edward Narayan. "Intra- and Inter-sample Variation in Wool Cortisol Concentrations of Australian Merino Lambs Between Twice or Single Shorn Ewes". Frontiers in Animal Science 3 (9 maggio 2022). http://dx.doi.org/10.3389/fanim.2022.890914.
Testo completoAbstract (sommario):
Stress in Merino sheep can cause a reduction in the quantity and quality of fine wool production. Furthermore, it has been found that environmental stress during pregnancy can negatively affect the wool follicles of the developing fetus. This study was part of a larger field investigation on the effects maternal shearing frequency on sheep reproductive and productivity outcomes. For this study, we investigated the intra- and inter- sample variation in wool cortisol levels of weaner lambs. We conducted two experiments, the first was to determine the intra- and inter- sample variation in wool samples taken from the topknot of weaned lambs, and the other aim was to determine any difference between maternal shearing treatment (single or twice shearing) on absolute wool cortisol levels of weaned lambs. In the first experiment, topknot wool was collected from 10 lambs, and each sample was further divided into four subsamples, leading to a total of 40 wool subsamples. For the second experiment, we collected the topknot from the 23 lambs produced by the shearing frequency treatment ewes (once or twice shorn). The samples were then extracted and analyzed using a commercially available cortisol enzyme-immunoassay in order to determine the concentration of cortisol in each of the samples. Statistical analysis for the first experiment showed that there was no significant difference between the subsamples of each topknot wool sample taken from each lamb (p = 0.39), but there was a statistical difference between samples (p < 0.001), which was to be expected. In the second experiment, there was a significant difference between the lambs born to the one shearing and two shearing treatments (p = 0.033), with the lambs of the twice sheared ewes having higher average wool cortisol levels [2.304 ± 0.497 ng/g (SE); n = 14] than the ones born to once shorn ewes [1.188 ± 0.114 ng/g (SE), n = 8]. This study confirms that the topknot wool sampling can be a reliable method adapted by researchers for wool hormonal studies in lambs. Second, ewes shorn mid-pregnancy gave birth to lambs with higher cortisol concentrations than ewes that remained unshorn during pregnancy. This result warrants further investigation in a controlled study to determine if maternal access to nutrition (feed and water) may impact on the HPA-axis of lambs.