Pasture Availability Research Articles

Effects of nutritional cues on the duration of the winter anovulatory phase and on associated hormone levels in adult female Welsh pony horses (Equus caballus)

BackgroundMares have an annual reproductive rhythm, with a phase of inactivity in midwinter. The aim of this study was to determine the impact of food restriction on physiological and metabolic hallmarks of this rhythm.MethodsOver three successive years, 3 groups of 10 mares were kept under natural photoperiod. A 'well-fed' group was fed to maintain the mares in good body condition; a 'restricted' group received a diet calculated to keep the mares thin and a 'variable' group was fed during some periods like the 'restricted' group and during some other periods like the 'well-fed' group, with the aim of mimicking the natural seasonal variation of pasture availability, but a few months in advance of this natural rhythm.ResultsWinter ovarian inactivity always occurred and was long in the restricted group. In contrast, in the 'well-fed' group, 40% of mares showed this inactivity, which was shorter than in the other groups. Re-feeding the 'variable' group in autumn and winter did not advance the first ovulation in spring, compared with the 'restricted' group. Measurements of glucose and insulin concentrations in mares from the 'restricted' group during two 24 h periods of blood sampling, revealed no post-prandial peaks. For GH (Growth hormone), IGF-1 and leptin levels, large differences were found between the 'well-fed' group and the other groups. The glucose, insulin, GH and leptin levels but not melatonin level are highly correlated with the duration of ovulatory activity.ConclusionsThe annual rhythm driven by melatonin secretion is only responsible for the timing of the breeding season. The occurrence and length of winter ovarian inactivity is defined by metabolic hormones.

Potential and constraints in the development of animal industries in China

Over the past three decades, the growth in terrestrial livestock and aquatic animal production in China has been much faster than the annual increase of 1.92% in total grain production. It was estimated that farming animals, including aquatic animals, would require a total of 860 million tons of feed in 2008, comprising almost equal portions of concentrates, pastures, and crop straw. Grain production amounted to 528 million tons in 2008, about half of which were available for use in animal feed after satisfying demand for human consumption. This situation will not change in the near future. Pastures from the natural grasslands supply about 290 million tons of dry matter, and are also unlikely to increase. In contrast, only one third of the 890 million tons of crop straw was used as animal feeds. We conclude that the availability of grain and pasture is the major constraint to further expansion of animal production, as well as crop straw which is not fully utilised. China needs to strategically structure the industries of its herbivores and the other domestic species, and to develop sustainable faming systems based on its available feed sources.

INVOLUÇÃO UTERINA, ATIVIDADE OVARIANA, PRIMEIRO CIO PÓS-PARTO E DISTÚRBIOS REPRODUTIVOS EM BÚFALAS

The aim of the present study was to evaluate some reproductive characteristics such as uterine involution, ovarian activity and first estrus after parturition, and reproductive disorders in buffaloes reared in the mixed system (floodplain and land / artificial pasture) in an experimental farm of Belém, Pará State, Brazil. A total of 62 female buffaloes and 167 postpartum periods were evaluated between 2002 to 2005 through gynecological and ultrasound examination. Animals were kept on artificial pasture during the rainy season (January-June) whereas on the floodplain areas with excellent availability of pasture during the dry season (July-December). The resumption of ovarian activity, verified by visual observation of the first estrus, was in average 47.06 ± 25.66 days, while the uterine involution verified by rectal palpation and ultrasound examination was 27.5 ± 7.77 days. The number of cases of abortion, retained placenta and embryonic death were 10 (5.90%), 13 (7.78%) and 14 (8.38%) cases, respectively, while the number of cases of uterine infection was 18 (10.7%). Regarding nonfunctional ovaries, 26 (15.56%) cases were found and two (1.19%) cases of ovarian hypoplasia, three (1.79%) cases of ovarian cysts and two (1.19%) cases of salpingitis were observed.KEYWORDS: Buffaloes, postpartum ovarian activity, reproductive disturbances, reproductive efficiency.

Effects of a short‐term increase in the nutritional plane before the mating period on metabolic and endocrine parameters, hepatic gene expression and reproduction in primiparous beef cows on grazing conditions

Sixty-four spring-calved primiparous crossbred cows paired by calving date and body condition score (BCS) at calving were used to study the effect of a short-term increase in the nutritional plane before the mating period on cow and calf performance, changes in metabolic and endocrine parameters and hepatic gene expression. At 48 ± 10 days post-partum (onset of nutritional treatment = day 0), cows were assigned to two treatments during 23 days: control (grazing of native pastures; NP; n = 31) and increased nutritional plane (NP improved with Lotus subbiflorous cv Rincon; IP; n = 33). Cow body weight (BW), BCS and total protein and albumin concentrations increased while urea and non-esterified fatty acids levels decreased from the beginning of the nutritional treatment in both groups, indicating the animal positive energy balance as forage growth and availability of pastures increased during spring. In addition, cow BW and BCS, as well as calf average daily gain and BW, were greater in IP than in NP cows groups. Insulin concentrations were less in IP than in NP (1.37 vs. 2.25 ± 0.26 μU/ml) because insulin increased owing to nutritional treatment only in NP cows. Hepatic insulin receptor mRNA at day 23 tended to be 1.5-fold greater, while insulin growth factor binding protein-3 mRNA expression was 1.7-fold greater in NP than in IP cows. Reproductive responses were not affected by nutritional treatment, but days to initiation of ovarian ciclicity (108 ± 10 days) were positively correlated with insulin concentrations. Grazing of improved NP for 23 days before the mating period did not improve cow reproductive performance but modified metabolic, endocrine and gene expression parameters, in agreement with greater nutrient and energy partitioning towards milk production, reflected in better calf performance.

Selenium Depletion Reduces Vaccination Response in Horses

Selenium Depletion Reduces Vaccination Response in Horses

“By endurance we conquer”: fat tailed sheep in the twenty-first century

In the temperate world, sheep are usually classified under two categories: wool and hair, where the latter are, in most cases, considered a relic of medieval times and not suitable for contemporary commercial sheep production. Additionally, in temperate countries, the sheep world is usually in black and white, as no other colors or mixing are commonly found. Interestingly, hair breeds are very adaptable to harsh environments like the churra breeds of the Iberian Peninsula or the Scandinavian hair breeds that thrive respectively in cold mountain ranges and sub-arctic islands. In the Tropics, however, the ovine world changes considerably: sheep have often (short) hair that tends to shed with changing seasons, and wool sheep are indeed a rare oddity. Additionally, tropical sheep are present in a vast array of coat-color patterns that eclipse the monochromatic nature of their relatives of temperate (mostly European) relatives. Besides these features, tropical sheep have a very distinctive and particular trait: the fat tail and/or fat rump, and are generally described as fat-tailed sheep (see Fig. 1). This morphological feature is characterized by an accumulation of fat mainly at the level of the hind quarters in varied shapes and volumes, and it is assumed to have similar physiological roles as those of the zebu or camel humps. Fat-tailed sheep distribution encompasses vast areas of the globe. They are the main ovine genetic resource in the Middle East and North Africa, Iran, Pakistan, Central Asian Republics, China and Mongolia, East and Southern Africa, and have important populations in agricultural export giants like Brazil or Australia. Interestingly, as to the best of our knowledge, in temperate countries, namely the European Union territory, there is only one autochthonous fat-tailed sheep breed: the Chios breed from the homonymous Greek Island near the Turkish coast. Regarding international diffusion, only two fat-tailed breeds may be classified as having acquired such preponderance: the Awassi breed original from several Middle East countries, improved in Israel and from there widespread to the entire world as a selected dairy breed and the Karakul (Astrakhan) breed form the former Soviet Union Republics of Central Asia that gained importance in the pelt production industry, curiously in fat-tailed sheep home range: Southern Africa and that nevertheless has lost the importance of the 1960s and 1970s. The wide distribution of fat-tailed sheep breeds may be explained by one particular trait: adaptability or endurance. In fact, these animals are able to thrive under extremely harsh conditions; they are able to tolerate hot weather, cope with dry environments with low pasture availability, able to walk long distances in search for pastures and drinking water, tolerate diseases and parasites, and even have gregarious and defense instincts that enable them to defend the flock from predators like jackals or foxes, similarly, to A. M. Almeida IICT–Instituto de Investigacao Cientifica Tropical & CIISA– Centro Interdisciplinar de Investigacao em Sanidade Animal, Lisbon, Portugal

Grazing effects on species composition in different vegetation types (La Palma, Canary Islands)

Grazing management is probably one of the most extensive land uses, but its effects on plant communities have in many cases been revealed to be contradictory. Some authors have related these contradictions to the stochastic character of grazing systems. Because of that, it is necessary to implement specific analyses of grazing effects on each community, especially in natural protected areas, in order to provide the best information to managers. We studied the effects of grazing on the species composition of the main vegetation types where it takes place (grasslands, shrublands and pine forests) on the island of La Palma, Canary Islands. We used the point-quadrat intersect method to study the species composition of grazed and ungrazed areas, which also were characterized by their altitude, distance to farms, distance to settlements, year of sampling, herbaceous aboveground biomass and soil organic matter. The variables organic matter, productivity and species richness were not significantly affected by grazing. The species composition of the analyzed plant communities was affected more by variables such as altitude or distance to farms than by extensive grazing that has been traditionally carried out on the island of La Palma involving certain practices such as continuous monitoring of animals by goat keepers, medium stocking rates adjusted to the availability of natural pastures, supplementation during the dry season using local forage shrubs or mown pastures and rotating animals within grazing areas Although some studies have shown a negative effect of grazing on endangered plant species, these results cannot be freely extrapolated to the traditional grazing systems that exert a low pressure on plant communities (as has been found in this study). We consider extensive grazing as a viable way of ensuring sustainable management of the studied ecosystems.

Podolian beef production on pasture and in confinement

From February to August 2007 the effect of rearing system (confined (C) v. free ranging (FR)) and season (spring v. summer) was evaluated on behaviour, immune and blood parameters and beef production (experiment 1). From February to August 2008, the effect of rearing system was only evaluated on beef production (experiment 2). A total of 12 Podolian young bulls were used each year. They were slaughtered at 18 and 15 months of age in 2007 and 2008, respectively. Herbage mass and pasture composition were monitored during the 2 years. Pasture availability, in terms of herbage mass and composition, as well as its seasonal development, was similar in the 2 years. In the first experiment, FR animals spent more time walking (P < 0.05), feeding (P < 0.001) and standing (P < 0.01) and showed a lower number of agonistic (P < 0.05) and non-agonistic social interaction than C animals (P < 0.01). Significant lower concentrations of serum urea nitrogen (P < 0.001) and creatinine (P < 0.10) in FR animals indicated a lower protein nutritional status due to inadequate protein availability at pasture. As a consequence, average daily gains (P < 0.05), slaughter weight (P < 0.05) and body condition score (P < 0.01) were lower in grazing animals as compared with C bulls. Cellular immune responsiveness was higher in FR animals (P < 0.05). Similarly, antibody titre to keyhole limpet hemocyanin was higher in FR bulls at the 2nd and 3rd month after antigen injection (P < 0.05), whereas it tended to be higher at the 4th month (P < 0.10). In both experiments, grazing negatively affected meat colour in terms of lightness. Eighteen-month-old bulls also showed lower final weight, weight gain and body conditions when kept outdoor: a possible consequence of nutrient deficits, as suggested by the metabolic status of FR animals. The same animals, however, benefited from FR in terms of natural behaviour expression and immune responsiveness. When the experiment was replicated the subsequent year, on animals slaughtered at 15 months of age, no differences between the performances of FR and C animals were detected. The earlier slaughter age system was also proportionally less dependent on external inputs as grazing was not extended to the dry season when herbage mass availability was lower.

Effect of fast-, medium- and slow-growing strains on meat quality of chickens reared under the organic farming method

The characteristics of meat quality, chemical and fatty acid composition, from fast-growing (FG) and medium-growing (MG) meat-type and slow-growing (SG) egg-type chickens reared under organic conditions were compared. Three-hundred and sixty 1-day-old male chicks, equally divided into three experimental groups represented by strains (FG: Cobb 700, MG: Naked neck Kabir and SG: Brown Classic Lohman) were housed into three poultry houses with outdoor pasture availability of 10 m2/bird located in the same Research Centre of the University of Perugia. All the birds were fed ad libitum the same diets formulated according to the European Union (EU) Regulations by using organic raw materials. Birds from the FG and MG groups were raised until 81 days, whereas birds from the SG group were raised until 96 days in order to achieve an acceptable market live weight. SG birds showed significantly (P < 0.01) higher breast meat drip and cook losses, Allo-Kramer shear values and collagen content. In comparison with FG and SG, MG exhibited a higher breast meat pH (5.86% v. 5.79% and 5.78%, respectively; P < 0.01) and a lower lightness (54.88% v. 57.81% and 56.98%, respectively; P < 0.05). Genotype dramatically affected the lipid content as well as the fatty acid composition of both breast and thigh meat. SG exhibited the lowest content of lipid, both in breast and in thigh meat, the lowest proportions of monounsaturated fatty acids (MUFA) and the highest proportions of polyunsaturated fatty acids (PUFA). The total n-3 PUFA of SG breast meat was double that of FG meat and intermediate with respect to MG birds (8.07% v. 4.07% v. 5.14% total fatty acids; P < 0.01). The fatty acid composition of thigh meat is similar to that of breast meat, but the differences among genotypes are less pronounced. Total saturated fatty acids were not affected by the genotype. In conclusion, meat functional properties of FG and MG strains appeared much more attractive both for industry and consumer (lower drip and cook losses and higher tenderness), whereas from a nutritional point of view, meat from SG appeared healthier (less fat and higher content of n-3 PUFA) and thus might better fit with the consumer’s expectations of organic products.

Dried yeast (Saccharomyces cerevisae) as a protein source for horses

The objective of this study was to evaluate the use of dried yeast in the diet of foals when replacing soybean meal to provide 0, 0.25, 0.50, 0.75 and 1.00 of the main protein source. Two trials were performed. Trial one was done to evaluate the influence of yeast on the digestibility of the five diets. Ten foals were kept in metabolic cages and five diets were tested twice. The experiment was repeated a second time, with foals receiving a different diet so that every diet was tested 4 times on a different animal. The concentrate was offered in a level of 2% of the body weight and Chloris guaiana hay was offered as roughage in a level of 1% of the body weight. In a second trial thirty ‘Brasileiro de Hipismo’ foals, aged between 12 and 14months, were used. They were kept on pastures of Cynodon dactylon c.v. Coastcross and Cynodon spp. c.v. Tifton 85, and the concentrate was offered twice a day in separate pens at a level of 2% of the body weight. The pastures were of good quality and the pasture availability was high. The experimental design was a 5×3 factorial (five levels of yeast and three groups of animals in different pastures), with two replicates/treatment. The foals were weighed and measured every 28days. Blood samples were collected at the end of the trial. The concentrate intake was measured daily. The pasture intake was measured through estimation of faecal output with chromic oxide and by the amount of acid detergent insoluble ash in the pasture, feed and faecal samples. The mean digestibility of dry matter, organic matter, crude energy and acid detergent fibre did not differ between the diets. A quadratic effect was observed for the digestibility of crude protein and neutral detergent fibre. Increasing the level of yeast in the diets did not have an influence on the average daily weight gain, heart girth gain, withers height gain, but linearly depressed the daily intake of the concentrate. However, the intake of pasture was not influenced by the different diets. The biochemical blood parameters total protein, albumin, globulin, urea, uric acid, creatinine, cholesterol, triglycerides, aspartate aminotransferase and gamma glutamyltransferase were not affected by increasing levels of dried yeast. It was concluded that dried yeast can be used as the only main protein source in the concentrate diets of 12month old foals.

Influence of climatic conditions on in vitro production of bovine embryos

Temperature and rainfall were analyzed daily during six years to evaluate their influence on in vitro production of bovine embryos. Weekly replications (n=480) were performed on 14,778 ovaries collected at slaughterhouses. Cumulus oocyte complexes (n=19,180) were fertilized with a pool of Bos taurus taurus semen in one incubator with 5% CO2. Presumable zygotes were cultured in gasified plastic bags with 5% CO2, 5% O2, and 90% N2. In the first year, cleavage and embryo yield were 60.3% and 15.6%, respectively, being lower (P&lt;0.05) than in the following years. Average cleavage rates were always lower in winter (P&lt;0.0001), thus producing less embryos. Winter climatic conditions had a negative influence on in vitro production, when cleavage and embryo yield declined, possibly because of reduced availability and growth of native pasture.

Performance of Nellore steers grazing on Panicum maximum Jacq cv. Mombaça receiving chopped sugar cane tops and protein supplementation

The aim of this study was to evaluate protein supplementation on the performance of steers grazing on Mombaça grass and receiving chopped sugar cane tops at a level of 0.80% of live weight (dry matter (DM) basis), during the dry season. Forage availability and quality of the experimental pasture were also evaluated. Thirty-two Nellore steers, weighing 300 kg (&plusmn; 25.80) of initial live weight, eight per treatment, were used. The statistical design was completely randomized and each steer group was allocated to one of four paddocks (1.125 ha paddock-1). All steers received a protein supplement at 0.40% of live weight (DM basis) and the four treatments consisted of the following four crude protein (CP) concentrations in supplements: 12.5, 25.0, 37.5 and 50.0% CP (DM basis). Average forage mass availability and green leaf blades availability were 10,069 and 2,195 kg of DM ha-1, respectively. Average CP, neutral fiber detergent (NDF) and in vitro dry matter digestibility (IVDMD) in forage mass were 6.87, 62.63 and 49.80%, respectively. Average daily gain was 0.61 kg steer-1 day-1 and these results show that the strategy of feeding steers in pasture, with chopped sugar cane tops (0.80% LW) and protein supplement with 12.50% CP (0.40% LW), during the dry season, allows high gain per area (363 kg live weight ha-1).

Reproductive physiology in female Old World Camelids

This review summarizes the basic reproductive physiology of dromedary and Bactrian camels. Camels are seasonal breeders with a relatively short breeding season during the cooler months. The onset of the breeding season can be influenced by local environmental factors such as temperature and pasture availability although decreased libido of the male as the environmental temperature increases is also a factor. Oestrous behaviour is highly variable in duration and intensity and is therefore unreliable for the detection of oestrus and difficult to relate to follicular activity in the ovaries. Camels are induced ovulators and thus normally only ovulate in response to mating. In the absence of mating, ovarian follicles tend to regress after a period of growth and maturity, whereas if male and females are kept together the female gets mated when the dominant follicle measures between 1.3 and 1.7 cm in diameter and the corpus luteum that develops has a lifespan of only 10–12 days. Peripheral concentrations of oestradiol increase with increasing follicle diameter until the follicle reaches 1.7 cm in diameter at which time they start to decrease even if the follicle continues to grow. The concentrations of progesterone remains low in non-mated animals but in mated camels it increases 3–4 days after ovulation (day of ovulation = Day 0) to reach maximum concentrations on Days 8–9 before decreasing rapidly on Days 10–11 in the non-pregnant animal. Ovulation can also be reliably induced using either Gonadotrophin Releasing Hormone (GnRH) or human Chorionic Gonadotrophin (hCG) but only when the follicle measures between 1.0 and 1.9 cm in diameter. Ovulation does not typically occur from follicles that grow beyond 2.0 cm in diameter but these follicles typically develop echogenic strands of fibrin as the follicle degenerates. The gestation period of camels is 13 months but the time of resumption of follicular activity following parturition is highly variable and influenced by nutritional status and lactation. Females that lose their offspring or have offspring which are weaned have a mature follicle develop within 10–12 days whilst in well-fed lactating females mature follicles do not develop until 30–60 days postpartum.

Herbage mineral nutrition indexed as tools for rapid mineral status diagnosis in tropical pastures

The animal production sector in the tropics is increasingly becoming challenged with the limited availability of pastures. There is need therefore to explore other options to suppliment the available pastures. The objectives of this study therefore was to understand how herbage mineral dilution indices used in developed countries as tools for controlled fertilisation, could be adapted in a tropical environment where high seasonal variations with regard to availability occur in pastures. A 3-year study was carried out in La Réunion Island, Indian Ocean. Fortynine farms, with swards made of either temperate or tropical grasses, grazed or mowed, were visited between four and five times a year. Dry biomass and dry matter contents were reported at each sample collection; whereas mineral indices were calculated from chemical analysis with a view to generate relevant fertilisation recommendations.Although the dry matter ( DM) values of less than 20% indicated a better stage of exploitation for the grasses, the data consistently indicate a decrease in the seasonal differences of dry biomass for grazed species. The use of indices, which combine both plant mineral status and pasture biomass, appeared relevant indicators for farmers and for pasture experts in tropical countries, and can be predicted through near infrared spectroscopy with an acceptable precision (R2 = 0.80, 0.60 and 0.91, for nitrogen , phosphorous and potassium, respectively). With reduced cost of pasture feed analysis using the NIRS, farmers can be able to make informed decisions basedon scientific data. Fertilisation is one of the potential options to improve pasture management as indicated by findings of this study. This is useful evidence-based information that could be incorporated in extension packages and resource materials for dissemination and subsequent adoption by livestock farming communities to improve produtivity.

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

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

Impacts and Economics of Wildlife Browsing on Tasmanian Pastures

The clearing of land for agriculture and the establishment of forestry plantations in Tasmania has led to changes in the distribution and population density of mammalian wildlife species. Populations of Bennett’s wallaby, Tasmanian pademelon, and common brushtail possum appear to have significantly increased over the past 50 years. Management of these and other species, including Forester kangaroo and introduced fallow deer on private land, is a contentious issue for landowners, animal welfare groups, and the government. Many farmers believe that browsing by native wildlife on pastures is significant and results in a considerable financial impost. However, limited research has been undertaken to quantify this wildlife browsing. The main control methods for these wildlife species include exclusion fencing, shooting, trapping, and poisoning. In 2005, the use of the poison 1080 (sodium monofluoroacetate) to kill wildlife was banned from use on public lands, and the Tasmanian Government plans to cease all use by 2015. This study investigated the effects of browsing wildlife on pasture within this region. We used a split plot design, consisting of 2 main treatments with 9 sub-plot treatments, to determine browse impact. Significant reductions in pasture biomass were recorded. The severity of browsing was affected by distance from native vegetation and also varied seasonally. Browsing damage declined with distance from native vegetation edge and was best explained by a logistic relationship. Browsing damage was severe during winter 2008 and varied between 100% at 25 m and 68% at 800 m from native vegetation edge. Browsing wildlife had the least impact during spring 2009 and reductions varied between 64% at 25 m and 0% at 800 m from native vegetation edge. The availability of pasture was found to be a determining factor in the distance and direction that wildlife would travel to browse. Browsing by wildlife also resulted in a reduction in ground cover.

Influence of stocking rate and mixed grazing of Angora goats and Merino sheep on animal and pasture production in southern Australia. 1. Botanical composition, sward characteristics and availability of components of annual temperate pastures

The effects of animal species (AS; Angora goats, Merino sheep or goats and sheep mixed grazed together at ratio 1 : 1) and stocking rate (SR; 7.5, 10 and 12.5 animals/ha) on the availability, botanical composition and sward characteristics of annual temperate pastures under continuous grazing were determined in a replicated experiment from 1981 to 1984. AS and SR had significant effects on pasture availability and composition and many AS × SR interactions were detected. The pastures grazed by sheep had significantly reduced content and proportion of subterranean clover and more undesirable grasses compared with those grazed by goats. There were no differences in dry matter availabilities between goat- and sheep-grazed pastures at 7.5/ha, but at 10 and 12.5/ha goat pastures had significantly increased availabilities of green grass, dead and green clover and less weeds compared with sheep pastures. There was a significant AS × SR interaction for the density of seedlings in May following pasture germination. Between July and January, the height of pastures was greater under goats than sheep but from January to March pasture height declined more on goat-grazed than on sheep-grazed pastures. There was an AS × SR interaction for incidence of bare ground. Increasing the SR increased bare ground in pastures grazed by sheep but no change occurred on pastures grazed by goats. Changes in pasture characteristics due to increased SR were minimised on pastures grazed by goats but the grazing of sheep caused larger and faster changes and the pastures were damaged at the highest SR. Goats did not always select the same herbage material as sheep, changed their selection between seasons and were not less selective than sheep. Angora goats were flexible grazers and continually adapted their grazing behaviour to changing herbage conditions. Goat grazing led to an increase in subterranean clover, an accumulation of dead herbage at the base of the sward, reduced bare ground, taller pastures in spring and a more stable botanical composition. Mixed-grazed pasture characteristics were altered with SR. With careful management Angora goats on sheep farms may be used to manipulate pasture composition, to speed up establishment of subterranean clover, to decrease soil erosion and to reduce weed invasion.

Survey of beef cattle producers to better understand factors influencing cattle movements from an exotic disease modelling perspective

In late 2008 a survey of beef cattle producers was undertaken to gain a clearer picture of how, why and when producers buy, sell, and move cattle, provide an insight into what influences on-farm decision making and to assist in the development of a simulation model for (modelling) cattle movements. The survey was targeted at beef producers in central and southern inland Queensland and north-western New South Wales. The survey was part of a project funded by the Federal Department of Agriculture, Fisheries and Forestry. The project focussed on utilising animal movement data from the National Livestock Identification System for 2006 and 2007 in the development of a national-scale spatial simulation model that would be used by national and state animal health agencies as a decision-support tool to assess and manage emerging animal disease threats. Major highlights arising from the study were that over half of the respondents were beef-only enterprises, with the remainder mixed enterprises (sheep and or cropping), and were predominantly in the breeding and growing production sector. The number of cattle movements, for farms having greater than 50 head, was not related to herd size. The most common movements other than buying or selling cattle were to a property owned by the producer close by (32%) or between properties for agistment (20%). Most types of cattle (cows, bulls, steers, etc) were sold within a few hundred kilometres of the property. The two main factors influencing when to sell cattle were reaching a target weight or matching a buyer/processor’s specification. Pasture availability, current prices and availability of suitable stock were also important factors.

The effects of pasture availability for twin- and triplet-bearing ewes in mid and late pregnancy on ewe and lamb behaviour 12 to 24 h after birth

This experiment was conducted to evaluate the effect of offering ewes two different feeding levels, during mid and late pregnancy, on ewe and lamb behaviour 12 to 24 h after birth. Romney ewes, bearing twin (n = 80) or triplet foetuses (n = 56), were allocated to a pasture sward height of 2 or 4 cm between 70 and 107 days of pregnancy. In late pregnancy (day 107 to 147), half of the ewes were reallocated the alternate sward height, which produced four treatments: 2-2, 2-4, 4-2 and 4-4. Ewes were weighed on days 65, 92, 107 and 130 of pregnancy and lamb live weights were recorded 12 to 24 h after birth. Twelve to 24 h after birth the maternal behaviour score (MBS) of the ewes were determined, whilst their lambs were tagged. After the lambs were released, the behaviour of each ewe and her lambs was observed for 5 min. Ewe treatment and litter size had no effect on ewe MBS. However, as MBS increased (ewes stayed closer to lambs during tagging), ewes bleated less in a high-pitch and were quicker to make contact with their lamb. During the observation period, ewes in the 4-4 treatment had a greater percentage of their bleats in a low pitch (P < 0.05) than ewes in the 2-2 and 4-2 treatment (61.3% v. 41.3% and 38.8% low bleats, respectively) and more lambs born to 4-4 ewes (95%) bleated than lambs born to 2-2 ewes (84%; P < 0.05). However, lambs born to ewes in the 2-2 treatment bleated earlier than lambs in all other treatments (P < 0.05). Lambs born to 4-4 ewes were less likely (P < 0.05) to move towards their dam in order to make contact than lambs born to 2-2 or 4-2 ewes (3.1% v. 16.9% and 16.7%, respectively). These findings suggest that under the conditions of the present study, ewe nutrition had little effect on maternal behaviour. However, lambs born to ewes offered 2 cm pasture sward heights during mid and/or late pregnancy (2-2, 2-4 and 4-2 treatments) displayed behaviour that demonstrated greater ‘need’ whereas lambs born to ewes offered 4 cm during mid and late pregnancy sought less attention from their dam.

Effect of supplementation of grazing dairy ewes with a cereal concentrate on animal performance and milk fatty acid profile

This work was conducted to investigate the effect of supplementing grazing ewes on pasture with a cereal concentrate on the milk fatty acid (FA) profile. Ninety Assaf ewes in mid lactation were distributed in 9 lots of 10 animals each and allocated to 3 feeding regimens: 1) pasture—ewes were only allowed to graze pasture (an irrigated sward of Lolium perenne, Trifolium pratense, and Dactylis glomerata); 2) PS—grazing ewes were supplemented with oat grain (700g/animal and day); and 3) TMR—ewes were fed ad libitum a total mixed ration (TMR; 80:20 concentrate/forage ratio). Milk yield and composition were recorded for 5 wk. The highest milk yield was observed in ewes receiving the TMR and the lowest in grazing ewes supplemented with oat grain. Productions of milk fat, protein, and total solids showed the lowest values in treatment PS. The atherogenicity index, which comprises C12:0, C14:0, and C16:0, in PS milk fat was no different from that observed in milk from animals on pasture (1.53 for pasture, 1.54 for PS, and 3.22 for TMR). Oat grain supplementation generated higher amounts of C18:0 and cis-9 C18:1 in milk fat than the pasture-only diet, but significantly decreased the levels of α-linolenic acid and most of intermediates of the process of biohydrogenation of this FA. Cis-9 trans-11 C18:2 and trans-11 C18:1, its precursor for endogenous synthesis in the mammary gland, were lower in PS (0.58 and 1.59g/100g of total FA) than in TMR (0.72 and 1.92g/100g of total FA) and very different from the results observed in grazing ewes receiving no supplement (1.21 and 3.88g/100g of total FA). Furthermore, the lowest levels of trans-10 C18:1 and trans-10 cis-12 C18:2 were detected in the milk fat of ewes fed pasture. It is concluded that, when pasture quality and availability do not limit dairy production, supplementation of grazing ewes with oat grain compromised the milk FA profile without any significant positive effect on milk production.