Ryegrass Pasture Research Articles

Infestation and natural parasitism of aphids in single and mixed pastures of black oats and ryegrass

Some species of aphids are major pests on cereal crops and grass pastures. Usually these pests are not adequately controlled in pasture lands that become sources of aphid infestations to cereal crops. The dynamics of aphids and the incidence of natural enemies are less known in pasture systems than in cereal fields. The objective of this work was to assess the aphid infestation and natural aphid parasitism in different pasture composition. Three hypotheses were tested: 1- the aphid species composition in pastures may vary according to the cereal species in the field; 2- the mixture of two plant species can modify the amount and diversity of aphids; 3- the plant species composition of pasture fields influences the parasitism of aphids. Empirical data were obtained from three Poaceae fields: black oats (Avena strigosa L.), ryegrass (Lolium multiflorum L.), and a mixed field of black oats and ryegrass. The most abundant aphid species was Rhopalosiphum padi followed by Sitobion avenae. Plant species composition increases the amount and the parasitism rates of aphids. The mixture of heavily infested black oats with a poorly infested ryegrass resulted in reduction of aphid infestation in comparison with heavily-infested single plant species field. This is possible because the conditions are favorable for the development of parasitoid populations. Aphidius colemani was the main parasitoid found in these areas.

Evaluation of beef cow and calf separation systems to improve reproductive performance of first-calf cows

A two-year study was conducted with the objective to compare the effects of a traditional 48-h calf withdrawal to early-weaning and repeated 48-h calf withdrawals on postpartum interval and measures of performance of first-calf cows. A total of 112 primiparous, Brahman×British cow–calf pairs were randomly allotted to three treatments over two consecutive years: early weaning (EW; permanent cow and calf separation); interval weaning (IW—48-h calf withdrawal; five times, 20 days apart); and control (CON; single 48-h calf withdrawal). Early-weaned calves were kept in an annual ryegrass (Lolium multiflorum) pasture and were fed supplemental concentrate (16% crude protein) daily at 1% of body weight. During the 48-h calf withdraw IW- and CON-calves were provided hay, water and free-choice access to the same concentrate supplement. Treatments were initiated at the start of a 90-day breeding season (average days postpartum=97±19). Blood samples were collected over 90 days on 10-day intervals for determination of progesterone concentrations. Resumption of cyclicity was defined as two consecutive samples with concentrations of progesterone ≥1.5ng/mL. Cow body weight was determined at the start (day 0), middle (day 41), and end (day 90) of the study, and cow body condition score was estimated using a nine-point scale where 1=emaciated and 9=obese on same days, only on year 2. Calf body weight was determined at the start and end of the study. Pregnancy was diagnosed by transrectal ultrasonography at approximately 45 days after the end of the breeding season. Cow body weight and body condition score at the beginning of the breeding season did not differ (369±38.2kg and 4.5±0.59, respectively); however, by day 90 body weight was greater (P<0.01) and body condition score tended to be greater (P=0.08) for EW versus IW and CON (385, 356, and 359kg; SEM=2.6; and 4.6, 4.1, and 3.9; SEM=0.20 for EW, IW, and CON cows, respectively). Calf BW was also greater (P<0.01) for EW calves versus IW and CON calves at the end of the study (170, 127, and 132kg for EW, IW, and CON calves, respectively; SEM=3.1). Cows in the EW and IW treatments had resumption of cyclicity earlier than CON cows (average days to resume cyclicity=65, 67, and 75 for EW, IW, and CON cows, respectively; SEM=0.2). By day 20 of the breeding season (corresponding to an average of 117 days postpartum), more (P=0.06) EW cows were cycling than CON-cows with IW cows intermediate. Cows exposed to IW had a greater (P=0.05) pregnancy rate than CON cows. Compared to a traditional, single-time, 48-h calf withdrawal, repeated 48-h calf withdrawal resulted in greater cow pregnancy rate with a reduced period of postpartum anestrus.

Nitrogen metabolism and rumen microbial enumeration in lactating cows with divergent residual feed intake fed high-digestibility pasture

Dairy cattle selected for negative residual feed intake (n-RFI; efficient) should maintain production while reducing dry matter intake over a lactation because of improvements in feed digestion and efficient use of nutrients. The objective of this study was to measure nitrogen (N) digestibility and rumen microbial community composition over a short period during early lactation in lactating Holstein-Friesian cows selected previously for divergent RFI. It was proposed that n-RFI cows would have greater apparent digestibility of N than the positive RFI (p-RFI; inefficient) animals, to compensate for the lower dry matter intake determined during selection for divergence. Sixteen 3-yr-old rumen-cannulated, lactating cows (56 ± 10d in milk) selected for n-RFI (n = 8) and p-RFI (n = 8) were housed in metabolism stalls and fed fresh vegetative ryegrass (Lolium perenne L.) pasture ad libitum as a sole diet during an 8-d digestibility study. Intake of nutrients and outputs of milk, feces, and urine were determined. Rumen parameters were determined by removing, weighing, and sampling digesta, and by cobalt-EDTA dilution. Intakes of N, dry matter, organic matter, or its components did not differ with RFI. Compared with p-RFI cows, n-RFI cows had a greater apparent N digestibility (77.2 vs. 75.5%), and a tendency toward greater dry matter and organic matter digestibilities. The n-RFI cows had a lower fecal N output (126 vs. 138g/d) and a lower partition of feed N to fecal N (23.1 vs. 24.7%) compared with p-RFI animals. We found no differences between phenotypes in the partition of N to urinary N or milk crude protein but did observe a trend for n-RFI cows to partition less N to milk casein (16.8 vs. 17.9%). Rumen digesta mass was similar for both groups, despite differences in calculated fractional liquid outflow rates, and most bacterial, archaeal, protozoal, and fungal communities were similar for both phenotype groups. In conclusion, dry matter intake and rumen function were similar for both phenotypes when the animals were fed highly digestible fresh ryegrass, but apparent digestibility of dietary N was higher in the efficient (n-RFI) cows. Future research should measure digestion parameters in cows with divergent RFI when fed diets differing in chemical composition (e.g., divergent crude protein contents).

Production parameters and forage loss of oat and rye grass pastures managed with beef heifers fed diets with energy supplementation

Production parameters of intercropped pastures of oat and rye grass managed with beef heifers supplemented with brown rice meal and/or protected fat were evaluated. Twenty-eight Charolais × Nellore crossbred heifers at initial average age of 18 months and initial average live weight of 274.9 kg were utilized in the experiment. Animals were kept on oat + rye grass pastures and distributed in the following treatments: no-supplementation (NS): heifers kept only in pastures; Megalac (MEG): supplementation with protected fat; brown rice meal (BRM): supplementation with BRM; BRM + MEG: supplementation with BRM plus protected fat. The greater participation of oat leaf was from July 5th to August 10th, 2009 and of rye grass, from August 30th to September 26th, 2009. The crude protein content increased until the 55th day (225.1 g/kg). Pasture total digestible nutrients presented a cubic behavior, with an average of 722.0 g/kg. The highest supply of leaf blades, 5.17 kg of dry matter/100 kg of live weight, was found in the second period. Pasture intake increased throughout the periods. Forage mass and support capacity of the animal did not differ between treatments, presenting means of 1245.02 kg of dry matter/ha and 882 kg of live weight/ha, respectively. Stoking rate, forage loss and pasture intake were not affected by the treatments. Supplementation of beef heifers with rice meal and/or protected fat did not change production parameters of oat + rye grass pastures or pasture intake. Increase in daily accumulation rate of dry matter and supporting capacity of the animals increases forage losses.

Behavior pattern of beef heifers supplemented with different energy sources on oat and ryegrass pasture

The objective of this study was to evaluate behavior patterns of heifers grazing on black oat (Avena strigosa Schreb.) and ryegrass (Lolium multiflorum Lam.), fed supplementation with brown rice meal and/or protected fat. A total of 28 Charolais × Nellore crossbred heifers at average initial age of 18 months and with initial live weight of 274.9±4.97 kg were used in the experiment. Animals were kept in oat + ryegrass pastures and distributed in the following treatments: no supplementation; Megalac (MEG): protected fat supplementation; supplementation with brown rice meal (BRM); and supplementation with BRM + MEG. The neutral detergent fiber (NDF) intake of pasture either in kg or in percentage of live weight was not changed by supply of supplement, but increased linearly (0.045 kg per day) over grazing periods. Supplementation with BRM and BRM + MEG reduced grazing time, 49.63%, in relation to non-supplemented animals and animals supplemented with MEG, 63.13%. Feeding seasons per minute increased over the experimental period with reduction in time spent in each feeding station. The number of bites per feeding station decreased linearly, with a variation of 34.48% in the late grazing period. Heifers supplemented with BRM and BRM + MEG require less time for grazing and increase their idle time, with no modification in displacement patterns within the paddocks and pasture ingestion. Grazing and idle time does not change in the distinct periods of pasture use, but rumination time increases with days of pasture use and with increase in NDF intake.

Método de amostragem e caracterização química da forragem consumida por bovinos em pasto consorciado de aveia e azevém

O presente ensaio foi conduzido com o objetivo de se estudarem diferentes métodos de amostragem de pasto e de se estimar a composição química da dieta consumida por novilhos Holandeses, mantidos em pastagem consorciada de aveia preta (Avena strigosa Schreb) e azevém (Lolium multiflorum Lam). Os métodos avaliados foram o corte da forragem rente ao solo (CFRS), o pastejo simulado (PSI) e a coleta de extrusa ruminal (CERU). Os teores médios de proteína bruta (PB), nutrientes digestíveis totais (NDT), fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA) foram de 9,7; 62,2; 64,5 e 33,1% para o tratamento CFRS; de 9,8; 65,4; 59,6 e 30,0% para o PSI, e de 11,4; 70,8; 51,6 e 25,5% para CERU, respectivamente. Não houve diferença estatística entre os métodos CFRS e PSI, todavia, em relação ao método CERU, ambos subestimaram a concentração proteica e a energética, e superestimaram a quantidade de parede celular presente na dieta. Conclui-se que a coleta da extrusa ruminal pode ser um método adequado para caracterizar a dieta consumida por novilhos em pastagem consorciada de aveia e azevém.

Physical properties and organic carbon content of a Rhodic Kandiudox fertilized with pig slurry and poultry litter

The impact of pig slurry and poultry litter fertilization on soils depends on the conditions of use and the amounts applied. This study evaluated the effect of organic fertilizers after different application periods in different areas on the physical properties and organic carbon contents of a Rhodic Kandiudox, in Concordia, Santa Catarina, in Southern Brazil. The treatments consisted of different land uses and periods of pig and poultry litter fertilization: silage maize (M7 years), silage maize (M20 years), annual ryegrass pasture (P3 years), annual ryegrass pasture (P15 years), perennial pasture (PP20 years), yerba mate tea (Mt20 years), native forest (NF), and native pasture without manure application (P0). The 0-5, 5-10 and 10-20 cm soil layers were sampled and analyzed for total organic carbon, total nitrogen and soil physical properties such as density, porosity, aggregation, degree of flocculation, and penetration resistance. The organic carbon levels in the cultivated areas treated with organic fertilizer were even lower than in native forest soil. The organic fertilizers and studied management systems reduced the flocculation degree of the clay particles, and low macroporosity was observed in some areas. Despite these changes, a good soil physical structure was maintained, e.g., soil density and resistance to penetration were below the critical limits, whereas aggregate stability was high, which is important to reduce water erosion in these areas with rugged terrain in western Santa Catarina, used for pig and poultry farming.

Influence of Sire Breed, Protein Supplementation and Gender on Wool Spinning Fineness in First-Cross Merino Lambs

Our objectives were to evaluate the effects of sire breed, type of protein supplement, level of supplementation and sex on wool spinning fineness (SF), its correlations with other wool characteristics and prediction accuracy in F1 Merino crossbred lambs. Texel, Coopworth, White Suffolk, East Friesian and Dorset rams were mated with 500 purebred Merino dams at a ratio of 1:100 in separate paddocks within a single management system. The F1 progeny were raised on ryegrass pasture until weaning, before forty lambs were randomly allocated to treatments in a 5 x 2 x 2 x 2 factorial experimental design representing 5 sire breeds, 2 supplementary feeds (canola or lupins), 2 levels of supplementation (1% or 2% of liveweight) and sex (wethers or ewes). Lambs were supplemented for six weeks after an initial three weeks of adjustment, wool sampled at the commencement and conclusion of the feeding trial and analyzed for SF, mean fibre diameter (FD), coefficient of variation (CV), standard deviation, comfort factor (CF), fibre curvature (CURV), and clean fleece yield. Data were analyzed using mixed linear model procedures with sire fitted as a random effect, and sire breed, sex, supplementary feed type, level of supplementation and their second-order interactions as fixed effects. Sire breed (P<0.001), sex (P<0.004), sire breed x level of supplementation (P<0.004), and sire breed x sex (P<0.019) interactions significantly influenced SF. SF ranged from 22.7 ± 0.2im in White Suffolk-sired lambs to 25.1 ± 0.2im in East Friesian crossbred lambs. Ewes had higher SF than wethers. There were significant (P<0.001) correlations between SF and FD (0.93), CV (0.40), CF (-0.94) and CURV (-0.12). Its strong relationship with other wool quality traits enabled accurate predictions explaining up to about 93% of the observed variation. The interactions between sire breed genetics and nutrition will have an impact on the choices that dual-purpose sheep producers make when selecting sire breeds and protein supplementary feed levels to achieve optimal wool spinning fineness at the farmgate level. This will facilitate selective breeding programs being able to better account for SF and its interactions with other wool characteristics.

Sward structure management for a maximum short‐term intake rate in annual ryegrass

AbstractThis study tested the hypothesis that different sward structures, which were constructed by varying the pre‐ and post‐grazing sward heights of annual ryegrass pasture (Lolium multiflorumLam.) in southernBrazil, affect the short‐term intake rate (STIR) by dairy cows. Treatments consisted of four sward‐management strategies defined by a combination of two pre‐ (25 and 15 cm) and two post‐grazing sward heights (10 and 5 cm): 15‐05, 15‐10, 25‐05 and 25‐10. A completely randomized block design with four replicates was used for the experimental design. TheSTIRwas determined by the double‐weighing technique. Jaw movements were evaluated using automatic recorders (IGER BehaviourRecorder). The results showed that treatment 25‐10 allowed the animals to collect more herbage with a greater bite mass and thus resulted in a greaterSTIR. Treatments in which sward height was reduced to 10 cm generally favoured the ingestion process than treatments with a post‐grazing sward height of 5 cm.

Glicerina bruta no suplemento para cordeiros lactentes em pastejo de azevém

Avaliou-se o efeito de níveis de glicerina bruta sobre o consumo de suplemento e o desempenho de cordeiros lactentes mantidos a pasto, além das características quali-quantitativas do pasto de azevém. Foram utilizados 32 cordeiros lactentes distribuídos nos tratamentos: 0, 10, 20 e 30% de glicerina bruta, em substituição ao milho, no suplemento isoproteico (18% PB) fornecido diariamente em quantidade equivalente a 2% do peso corporal. Não houve efeito (P&gt;0,05) dos níveis de glicerina bruta sobre as características qualitativas e quantitativas do pasto, na composição de proteína bruta e fibra detergente neutro e na carga animal suportada pela pastagem, nem no consumo de suplemento, ganho de peso médio diário e o número de dias até o abate dos cordeiros. Níveis de até 30% de glicerina bruta, em substituição ao milho, no suplemento fornecido para cordeiros lactentes pastejando azevém não comprometem o consumo de suplemento, desempenho e período de terminação dos animais.

Production and Economics of Grazing Steers on Rye–Annual Ryegrass with Legumes or Fertilized with Nitrogen

ABSTRACTCool‐season legumes have potential to replace N fertilizer in annual cool‐season grass pastures, thus improving returns to producers. The objective of this 3‐yr study was to compare the performance and economics of stocker cattle (Bos spp.) grazing rye (Secale cereale L.)–annual ryegrass (Lolium multiflorum Lam.) under two N systems. Paddocks were planted in early September 2008 through 2010 and contained rye–annual ryegrass with 112 kg N ha−1 (fertilized so that a total of soil residual N plus fertilizer N would equal 112 kg N ha−1) (RR‐N) or contained a rye–annual ryegrass with annual legume mixture (arrowleaf clover [Trifolium vesiculosum Savi], field pea [Pisum sativum L.], and hairy vetch [Vicia villosa Roth]) (RR‐Leg). Steers (307 ± 55 kg initial body weight) were weighed every 28 d and stocking rates were adjusted based on forage mass with put‐and‐take steers. Forage mass, forage allowance, and stocker average daily gain (ADG) and total gain (TG) were measured every 28 d. Results show similar performance between RR‐N and RR‐Leg systems in grazing days (average 367 d ha−1), ADG (average 1.065 kg per head d−1), and TG (average 390 kg ha−1). While the 3‐yr average total cost associated with the RR‐N system (US$569.88 ha−1) was greater than the RR‐Leg system ($550.57 ha−1), there were no differences in gross revenue (average $815.91 ha−1) or expected net returns (average $255.68 ha−1) between systems. Annual legumes could be a viable replacement for commercial N fertilizer in rye–annual ryegrass pastures although adoption may be limited due to ease of N fertilizer application.

Herbicide application and direct drilling improves establishment and yield of chicory and plantain

AbstractThe herbs chicory ( C ichorium intybus L.) and plantain ( P lantago lanceolata L.) are increasingly popular summer forage cropping options for dairy producers. However, the impact of different establishment methods on their productivity is largely unknown. Four establishment methods for chicory and plantain crops sown into non‐cultivated ryegrass pastures in spring were compared. Establishment methods included direct‐drilling or broadcasting seed into existing pastures, with or without herbicide application before sowing in a 2 × 2 factorial design. It was hypothesized that plant establishment and growth would be enhanced by spraying to kill existing ryegrass pasture and direct‐drilling herbs (Spray and Drill, SD) compared with broadcasting seed with no herbicide application (Unsprayed and Broadcast, UB). This hypothesis was supported with an additional 2·1–2·3 t DM ha−1 grown over 201 d from swards established by SD, compared with swards established by UB. The SD method also increased the plant density of the herbs and reduced the proportion of weed species. Spraying and direct drilling is more expensive than broadcasting seed with no herbicide application, but the increase in yield means that extra feed can be supplied at less than half the cost of purchasing the equivalent amount of feed. Therefore, for optimal economic outcomes, chicory and plantain swards should be established by applying herbicide to existing pasture and direct‐drilling seed.

Efectos del tipo de carbohidrato sobre la captura de nitrógeno y producción de leche bovina

El estudio tuvo por objetivo determinar si la suplementación con dos fuentes de carbohidratos de distinta tasa de degradación disminuía la concentración de amoníaco al incrementar la captura de nitrógeno por las bacterias ruminales en vacas en lactancia, pastoreando ballica perenne (Lolium perenne), con alto contenido de proteína. Se utilizaron 4 vacas con cánula ruminal distribuidas en 4 tratamientos con distintas proporciones de maíz:avena, como suplemento: T0 (control): sin suplementación; T1: 80:20; T2: 50:50 y T3: 20:80. Se utilizó un diseño de cuadrado latino de 4 x 4 y los efectos se midieron en la concentración de amoníaco ruminal, amoníaco y urea en sangre y urea en leche además de producción y composición de la leche. La pastura de ballica perenne presentó un 23 % de proteína bruta y 14,4 MJ*kg-1 de energía metabolizable.El aporte energético en los tratamientos con suplementación fue similar, ajustando la cantidad de suplemento diario. Los tratamientos con suplementación, a excepción del T3, presentaron una concentración de amoníaco ruminal menor (p0,05). Tampoco hubo diferencias (p&gt;0,05) para concentraciones de amoníaco plasmático, urea plasmática, producción de leche, contenido de grasa, proteína, energía y urea en leche. El suministro de mezclas de maíz y avena a vacas en praderas de ballica de alto contenido de proteína degradable, reduce la concentración de amoníaco ruminal, pero este efecto no se traduce en mayores producciones de leche o cambios en sus componentes.

Características da ingestão de forragem por cordeiras nos estádios fenológicos da pastagem de azevém

Foram estudadas as características do processo de ingestão de forragem por cordeiras em azevém (Lolium multiflorum Lam.) nos estádios fenológicos vegetativo, pré-florescimento e florescimento, por meio de testes de pastejo e da técnica da dupla pesagem. O delineamento experimental foi o inteiramente ao acaso, com três tratamentos e cinco repetições no estádio vegetativo e seis nos demais estádios. Os diferentes estádios fenológicos não influenciam a taxa de ingestão, a massa do bocado e a profundidade de bocado quando a oferta de forragem não é limitante ao consumo. O aumento na taxa de bocados é o mecanismo utilizado por cordeiras para manter a taxa de ingestão constante. Os modelos de regressão múltipla indicam que, dentre os atributos do pasto, sua altura é o de maior importância para determinar mudanças no comportamento ingestivo de cordeiras.

The influence of herbage mass and supplementary feeding on nutrient flows and animal performance in grazing, lactating ewes

SUMMARYThe present paper examines the effect of the type of supplement given to grazing ewes in early lactation on the performance of ewes and lambs on temperate sown pastures. Lactating ewes grazed perennial ryegrass pastures at either low- or high-herbage masses, between days 8 and 96 of lactation. On the low-herbage mass treatments, ewes were either unsupplemented or received either an energy supplement (sugarbeet pulp) or a protein supplement (1:1 sugarbeet pulp:formaldehyde-treated soyabean meal) between days 8 and 50 of lactation. The provision of supplements or the higher herbage mass led to increases in live weight (LW) and body condition score of ewes during days 8–50 of lactation, while unsupplemented ewes on the low-herbage mass treatment lost LW and had lower body condition scores. After supplementation finished, previously supplemented ewes or those grazing the higher herbage mass lost LW and condition, while unsupplemented ewes grazing the low-herbage mass gained both LW and condition. Non-treatment factors such as ewe dentition score significantly affected ewe and lamb LW gains. Regression analyses indicated that lamb LW gains between days 8 and 50 of lactation were 40–60 g/d greater in lambs from supplemented ewes or ewes grazing the higher herbage mass cf. unsupplemented ewes. Overall, there was no difference in the response of ewes or lambs to the type of supplement. Milk yields were estimated in a subset of ewes (replicate 4). Ewes on the high-herbage mass treatment or those supplemented with protein had higher milk yields than those on the low-herbage mass treatment or those given the energy supplement. Supplemented ewes in this replicate had higher metabolizable energy intakes (MEIs). Measurements of digesta flow in a further subset of ewes indicated that both supplements resulted in greater ruminal and post-ruminal supplies of energy and protein than in the unsupplemented ewes at the lower herbage mass, but differences in ruminal and post-ruminal nutrient provision between the supplements were less than had been intended. It is suggested that this is the reason for there being no statistical difference in the performance of ewes and lambs in response to the type of supplement.

Rumination behavior of grazing dairy cows in response to restricted time at pasture

The short-term adaptations of cattle behavior to time restrictions at pasture are poorly understood. This study explored the diurnal rumination pattern of dairy cows in response to restrictions to time at pasture. Six groups of eight Holstein–Friesian cows (470±47kg, 35±9days in milk) were strip-grazed on a perennial ryegrass (Lolium perenne L.) pasture over 21days (2 groups per treatment) for either 4h after each milking (2×4), one period of 8h between milkings (1×8), or 24h excluding milking times (control, CTL). All cows were equipped with HR Tag™ rumination collars which recorded chewing activity and regurgitation of digesta boluses during rumination. Cows in 1×8 reduced daily rumination time by 36% compared with cows in 2×4 and CTL (304, 402 and 423 SED 26.3min, respectively). There were no differences in the average intervals between regurgitation of digesta boluses (48.9±0.96s) and average interval between chewing actions was also similar (0.7±0.02s) between treatments. Treatment affected the diurnal rumination pattern. There was little rumination during the time at pasture for the restricted cows (1×8 and 2×4), whereas the CTL cows ruminated for almost a third of the time between the am and pm milking. In all treatments, cows ruminated the longest during the night. These results suggest grazing dairy cows modulate their time for rumination to compensate for a reduction in available grazing time. This behavioral study contributes to the understanding of changes in rumination behavior and associated effects in grazing dairy cattle in response to hunger.

Foraging behavior and ruminal fermentation of dairy cows grazing ryegrass pasture alone or with white clover

The objective of this work was to evaluate the influence of pasture composition and regrowth age on the relationship between feeding behavior and ruminal fermentation in dairy cows grazing perennial ryegrass with or without white clover. The experiment was carried out in a 2x2 factorial arrangement, with two sward types and two ages of regrowth. Swards of perennial ryegrass sown alone (PRG) and of perennial ryegrass mixed with white clover (GC) were evaluated. Twelve late-lactation Holstein cows, fistulated at the rumen, were distributed in a 4x4 latin square experimental design with four 12-day periods. Daily distribution of grazing was similar in the PRG and the GC swards, but the concentration of rumen volatile fatty acids (VFA) was higher and the proportion of propionate was lower on mixed swards during the day. Daily distribution of grazing was similar in pastures of different ages. However, in the oldest swards, rumen fluid pH increased and VFA concentration decreased after evening milking. Time spent grazing does not influence ruminal fermentation, which depends on the changes that occur as different sward layers are grazed.

The evaluation of endophyte toxin residues in sheep fat

AIM: To monitor changes in concentrations of lolitrem B and epoxy-janthitrems in the fat of sheep grazing perennial ryegrass infected with wild-type- and AR37-endophyte, respectively, during the time of year when ryegrass staggers would be expected to be observed. METHODS: Ten 5-month-old lambs with no previous exposure to endophytes were grazed on either wild-type (containing lolitrem B, n = 5) or AR37 (containing epoxy-janthitrems, n = 5) endophyte-infected perennial ryegrass (Lolium perenne L.) pastures between October 2008 and June 2009. Animals were regularly assessed for ryegrass staggers using the Keogh scale (0 = no signs, 5 = severe tremors). When a score of > 3.5 was observed animals were removed from the treatment pastures for 1 month. Fat biopsy samples were taken from each animal at approximately monthly intervals and analysed for endophyte metabolites using high performance liquid chromatography (HPLC) methods developed during this study. Regular herbage samples were also taken and concentrations of endophyte metabolites measured. RESULTS: Efficient and reproducible methods to analyse both lolitrem B and epoxy-janthitrems in fat were developed. Concentrations of lolitrem B and epoxy-janthitrems in herbage and in sheep fat increased from late November to peak in mid-February. Ryegrass staggers was observed in both groups of sheep at this time. Following 1 month of grazing non-infected pasture mean concentrations in fat of lolitrem B decreased by 43% from 61.8 to 35.3 ppb, and of epoxy-janthitrems by 38% from 1032.0 to 639.5 ppb. Maximum concentrations in herbage of epoxy-janthitrems (35.7 ppm) were higher than of lolitrem B (3.4 ppm), but signs of staggers were less severe in sheep grazing pasture containing the former compared with the latter (median Keogh scores in late February were 2 and 3, respectively), consistent with epoxy-janthitrems being low potency toxins. CONCLUSION: This study demonstrated that concentrations of epoxy-janthitrems and lolitrem B in sheep fat increased quickly during the initial phase of the study when concentrations in pasture increased, and decreased when animals were removed from pastures containing these compounds. These data will be used in the risk assessment of the endophyte metabolites.

Stocker Growth on Rye and Ryegrass Pastures Affects Subsequent Feedlot Gains and Carcass Traits

Stocker Growth on Rye and Ryegrass Pastures Affects Subsequent Feedlot Gains and Carcass Traits

Effects of wild-type, AR1 and AR37 endophyte-infected perennial ryegrass on dairy production in Victoria, Australia

A 3-year experiment compared the effects of wild-type ryegrass endophyte and two novel endophytes on milk production in dairy cattle. On three 9.9-ha farmlets in West Gippsland, Victoria, pasture swards were established that were dominant in perennial ryegrass (Lolium perenne) infected with either wild-type, AR1 or AR37 endophytes. Each farmlet was stocked with 25 spring-calving Holstein–Friesian cows, which rotationally grazed nine paddocks within their farmlet during three lactations over 3 years. The three endophytes are known to produce different alkaloids, with wild-type producing ergot alkaloids, lolitrems and peramine, AR1 producing peramine and AR37 producing epoxy-janthitrems. These alkaloids were present in fresh pasture as well as hay and silage made from that pasture. Grazed pasture comprised 53% of estimated annual DM intake. The proportion was least from December to March when the daily ration of 2 kg DM/cow.day cereal grain was increased to 6 kg/day and forage supplements were fed consisting of purchased lucerne (Medicago sativa) hay and pasture silage grown on the farmlets. There were no differences in pasture accumulation rates or nutritive characteristics of ryegrass pastures on the three farmlets and no differences in the production of milk, fat or protein by cows grazing pasture infected with the three endophytes. Ryegrass staggers was only observed in four cows consuming the wild-type-infected ryegrass in the first year when the highest concentrations of lolitrem B were recorded in pasture. Soil samples showed lower numbers of root aphids (Aploneura lentisci), mealybugs (Pseudococcidae) and pasture tunnel moths (Philobota spp.) beneath ryegrass infected with the AR37 endophyte compared with the other two endophytes. Numbers of redheaded (Adoryphorus couloni) and blackheaded (Aphodius tasmaniae) cockchafers did not differ between treatments. Under dairy management and supplementary feeding regimes common to south-eastern Australia, the novel endophytes AR1 and AR37 had no effect on the milk production compared with the wild-type endophyte, and did not cause ryegrass staggers.