Herbage Dry Matter Research Articles

Androgenesis in a Lolium multiflorum X Festuca arundinacea hybrid to generate genotypic variation for drought resistance

The pentaploid hybrid of Lolium multiflorum and Festuca arundinacea (2n = 5x = 35) combines the high growth rate of L. multiforum with the drought resistance and freezing-tolerance of F. arundinacea. Unfortunately, it also displays the deleterious traits associated with Festuca, namely those associated with high leaf fibre content giving rise to poor palatability and digestibility. To access different combinations of these characters, anther cultures were initiated and regenerated into single embryo derived plants. The anther culture method was very productive since out of a total of 2349 androgenic plants derived from the same parent plant, 57% were green plantlets, although only 507 (22%) subsequently established into plants following transfer to soil. Chromosome counts of randomly selected lines showed that plants with euploid chromosome numbers (14, 21, and 28) would appear to have selective advantage during regeneration. There was wide variation between mature androgenic plants grown under field conditions in plant height, leaf length, leaf width, tiller number and herbage dry matter. The variation between genotypes in response to drought stress was assessed by placing replicate clones under rain-out shelters or under irrigated control conditions in the field. Herbage dry matter under drought was higher in a number of androgenic lines than either parents, but not higher than the pentaploid hybrid. Androgenesis was shown to be a highly effective procedure to expose diverse phenotypic variation all derived from the same Lolium × Festuca hybrid genotype.

Balanced and adequate potassium and phosphorus nutrition of pasture

Pasture production responses from applications of four rates each of potassium (K) (0, 112.5, 225, 450 kg ha‐1) and phosphorus (P) (0, 60, 120, 240 kg ha‐1) in a factorial design were measured in a mowing trial with 60% of clippings returned at a K‐ and P‐responsive site (54.6 μg K ml‐1 and 9 μg Olsen P ml‐1) at Woodlands in Southland, New Zealand over 2 years. There were large significant responses in total pasture dry matter (DM) production to K and P. A bivariate Mitscherlich‐related equation accounted for 97% of the variation in measured values of total DM yield, 94–99% of the variation in ratios of K, P, and nitrogen (N) concentrations in mixed herbage, and 99–100% of the variation in nutrient ratios in white clover, summed or averaged over 2 years. The fitted equations were used to identify combinations of fertiliser P and K rates and ratios of K and P concentrations in mixed herbage and clover that resulted in balanced and adequate nutrition. Two nutrient elements are in balance when the yield response to one added on its own equals the response to the other added on its own, both in relation to the maximum yield. Balanced nutrition in total DM occurred at a K/P ratio of 5.1–7.4 for mixed herbage and 4.2–7.9 for clover, and were highest at higher rates of K and P. For balanced nutrition at 95% relative yield, K/P ratios were 6.8 for clover and 6.7 for mixed herbage. Fertiliser K/ (K + P) ratios for balanced nutrition increased from 0.5 for fertiliser expenditure of $50 ha‐1 to 0.7–0.8 for expenditure of $100–200 ha‐1. Modelled yield at the fertiliser K/(K + P) ratio for balanced nutrition in mixed herbage and clover DM was similar to maximum modelled yield. Mixed herbage and clover K/P ratios derived from economically optimal fertiliser K/P ratios were 6.2–6.6 and 5.6–6.7, respectively. Using N concentration as an internal standard, nutrient adequacy is defined as the herbage yield with K and P in physiological balance relative to the maximum yield with K and P in physiological balance and expressed as RY [KP]. At 95% RY [KP], adequate nutrition was achieved at K/N of 0.77 for mixed herbage and 0.46 for clover. Overall, the results from the trial reported here confirm that ratios of nutrient concentrations are useful indicators of balanced and adequate K and P nutrition for total pasture production. Mixed herbage or clover nutrient concentrations and ratios were both effective indicators of balanced and adequate nutrition.

Comparative digestion of herbage by two breeds of sheep: effects of grass maturity stage and level of intake

AbstractTwo trials were conducted to study the effect of the stage of maturity of fresh herbage on its digestibility by two breeds of sheep (Churra v. Merino). The sward consisted of a mixture of grasses and clover, and was harvested either in late May (early cut, EC) or in late July (late cut, LC). In each trial, 12 mature sheep of each breed were used. Each animal received a different amount of fresh herbage, so that levels of food intake ranged between 8·1 and 24·7 g dry matter (DM) per kg body weight per day. EC herbage showed higher crude protein content (116 v. 67 g/kg DM), lower neutral-detergent fibre concentration (494 v. 664 g/kg DM) and higher DM digestibility (0·687 (s.e. 0·005) v. 0·463 (s.e. 0·007)) than the LC herbage. DM digestibility coefficients observed in Churra (0·694 (s.e. 0·028) for EC and 0·476 (s.e.0·028) for LC herbage) tended to be greater than those observed in Merino sheep (0·680 (s.e. 0·021) for EC and 0·452 (s.e. 0·040) for LC herbage). With the EC herbage DM digestibility tended to decrease as the level of intake increased. Samples of dried herbage were incubated in the rumen of Churra and Merino sheep to determine the DM degradability by the in situ technique. Fractional degradation rates (c values) were significantly faster in the rumen of Churra than in Merino (0·046 (s.e. 0·003) v. 0·031 (s.e. 0·002)), with large differences between breeds in the DM disappearance rates at intermediate incubation times, and no significant differences between Churra and Merino sheep in the mean a + b values. Microbial N supply, calculated from the urinary excretion of purine derivatives, was significantly affected by the herbage maturity stage and by the level of DM intake, but not by the breed of sheep. It is suggested that differences between breeds of sheep in food digestibility may be related to their ability to digest fibrous diets.

Predicting Leaf/Stem Ratio and Nutritive Value in Grazed and Nongrazed Big Bluestem

Recent advancements in describing morphological development of perennial grasses have provided a useful index for identifying dates to harvest hay or graze pasture. The objective of this study was to determine the relationship between big bluestem (Andropogon gerardii Vitman) morphological developmental stage, days from 1 May, and accumulated growing degree days (GDD) and leaf/stem ratio, crude protein (CP), and neutral detergent fiber (NDF) in grazed and nongrazed swards. The grazing experiment was conducted in eastern Nebraska during 1997 and 1998. Six grazing treatments consisting of all combinations of two herbage allowances (22 or 66 kg of herbage dry matter per animal unit day) and three grazing dates (late May, early June, and mid‐June) were randomly assigned to seven paddocks (900 m2) in each of four blocks along with a nongrazed control treatment. Random samples consisting of 50 or more tillers were hand‐clipped weekly at ground level in each paddock beginning in late May and ending in early August. Morphological developmental stage of the samples were determined, and a mean morphological stage based on shoot count [mean stage count (MSC)] was calculated. Samples were hand‐separated to determine leaf/stem ratio and analyzed for CP and NDF. Regression analysis showed that good relationships were found between MSC (R2 = 0.61–0.81), days from 1 May (R2 = 0.45–0.76), and GDD (R2 = 0.44–0.74) and leaf/stem ratio in nongrazed big bluestem and high herbage allowance swards. All three were adequate predictors of nutritive value and leafiness, but MSC may be more useful to researchers who want a more descriptive measure of plant morphological development, particularly when comparing cultivars or species.

In‐Season Fertilizer Nitrogen Applications for Soybean in Minnesota

Predicted physiological factors and a limited number of field studies have resulted in debate regarding the recommendation of in‐season fertilizer N for soybean [Glycine max. (L.) Merrill]. The objective of our research was to evaluate several in‐season N fertilization strategies on soybean seed yield response as well as to measure the effect of fertilizer N additions on late‐season plant N concentrations and accumulation, seed N removal, seed protein, and seed oil composition. The research was conducted at 12 sites in the southern soybean‐growing region of Minnesota in 1998 and 1999. A combination of (i) application time (July vs. August), (ii) placement method (broadcast vs. knifed), and (iii) N source (urea vs. poly‐coated urea) gave five N treatments plus a control at all sites. Seed yield did not respond to the fertilizer N treatments at any of the 12 sites; however, a combined analysis indicated a significant increase (generally less than 0.06 Mg ha−1) from using polymer‐coated urea or applying the urea in August. Herbage dry matter (DM) and herbage N concentrations at the R6 stage were not affected by any of the N fertilizer strategies. Although soybean seed protein was statistically different among the treatments, protein was only increased 0.4 g kg−1. Soybean oil concentration was not affected by fertilizer treatments. In general, polymer‐coated urea, knifed applications, and August applications increased soil NO3–N in the 0‐ to 30‐cm layer at R6 relative to standard urea, broadcast applications, and July applications. Even though in‐season N fertilizer created greater levels of available soil N at all 12 sites during soybean pod filling, seed yield was not improved compared with unfertilized control plots at any site. As a result, the University of Minnesota does not recommended in‐season N fertilizer applications for soybean production.

Dinâmica do acúmulo de matéria seca em pastagens de Tifton 85 sob pastejo

O acúmulo de forragem é o resultado líquido de dois processos concomitantes e antagônicos: o crescimento e a senescência e morte de tecidos. O presente trabalho teve por objetivo avaliar o processo de produção de forragem através do estudo de seus componentes; crescimento e senescência. Os tratamentos corresponderam a quatro condições de pasto caracterizadas pelas alturas de 5, 10, 15 e 20 cm, mantidas constante através do pastejo por ovinos em regime de lotação contínua e taxa de lotação variável. O delineamento experimental utilizado foi o de blocos completos casualizados, com quatro repetições. Foram avaliadas as seguintes respostas: alongamento de hastes, alongamento de folhas, senescência, filocrono e o número de folhas por perfilho. Os resultados revelaram um padrão estacional de produção de forragem, com as maiores taxas de crescimento e senescência sendo observadas nas alturas de pasto mais altas (15 e 20 cm). O filocrono variou com a época do ano e com a altura de pasto, revelando uma alta associação com variações em temperatura do ar, disponibilidade de água no solo e índice de área foliar do pasto. As alturas de 15 e 20 cm resultaram na maior produção de matéria seca. Os mesmos princípios e relações originalmente descritos para plantas forrageiras de clima temperado são válidos para plantas tropicais dentro do contexto das limitações fisiológicas e de ambiente inerentes para cada condição.

The reclamation of bracken‐dominated pastures in Bulgaria using asulam and fertilizers

Bracken (Pteridium aquilinum) is a major weed of considerable economic concern in upland pastures in Bulgaria and elsewhere in Europe. Between 1993 and 1998, a field experiment was carried out to test methods for restoring productive meadows. Initially, spraying asulam (4·8 kg a.i. ha−1) was used to control the bracken on the site; this was achieved in terms of reduced frond densities and a higher level of grassland establishment. This grassland was dominated by Vicia cassubica and the perennial grasses Agrostis vulgaris, Dactylis glomerata, Festuca rubra, Holcus lanatus and Poa pratensis.After 2 years, a fertilizer addition experiment was started with four treatments (no fertilizer; addition of phosphorus; addition of nitrogen and phosphorus; addition of nitrogen, phosphorus and potassium. The phosphorus and potassium fertilizers were applied annually in the early spring at 80 kg of P ha−1 year−1 and 50 kg of K ha−1 year−1, and nitrogen was added at the start of grass growth at 60 kg of N ha−1 year−1. At the same time, a twice‐yearly hay‐cutting regime was implemented. Fertilizer addition increased both the quantity and the quality of the resulting grassland. The herbage dry matter was increased by at least a factor of two depending on fertilizer combination, and there was an increase in grass and legume cover and a decrease in both weed cover and bracken recovery. However, although bracken recovery was inversely related to grassland production, there was a consistent increase in bracken density across all treatments between 1997 and 1998, suggesting that increasing herbage biomass merely delays bracken recovery. The implications of these findings are discussed.

Demografia do perfilhamento e acúmulo de matéria seca em coastcross submetido a pastejo

Os objetivos deste trabalho foram identificar o padrão populacional do perfilhamento de coastcross (Cynodon spp. cv. Coastcross) sob pastejo, e avaliar o acúmulo de matéria seca de sua forragem. Foram avaliados densidade populacional, taxas de natalidade e mortalidade de perfilhos, proporção de perfilhos florescidos e acúmulo de matéria seca. Os tratamentos consistiram em manter a altura do pasto em 5, 10, 15 e 20 cm, utilizando ovinos sob regime de lotação contínua e taxa de lotação variável. Pastos mais baixos (5 cm) apresentaram as maiores densidades populacionais de perfilhos. O florescimento foi mais intenso durante o final do inverno e início da primavera. Ocorreu alta renovação de perfilhos durante o verão. As condições de seca promoveram fortes efeitos sobre as taxas de natalidade e de mortalidade de perfilhos. Não houve efeito (P>0,10) de tratamento sobre as taxas de acúmulo de matéria seca.

Chemical Induced Vigour for Heterotic Effects on Yield and Quality of Essential Oil in Palmarosa (Cymbopogon martinii Wats)

ABSTRACT The efficacy of a few selected synergistic combinations of ethephon as chemical hybridizing agent for stimulatory heterotic effects on biomass and essential oil yield in palmarosa plants has been tested. Ethephon in solo treatment as well as in various synergistic combinations with the two precursor compounds of m-coumaric acid/3-hydroxycinnamic acid-spermidine and putrescine, and with four micronutrients, Fe-EDTA, CuSO4, ZnSO4, MnCl2 was “mist sprayed” during the vegetative and anthesis growth stages of palmarosa plant. Ethephon treatment along with spermidine (2%) or putrescine (2%) in conjunction with any of the four micronutrient (0.5% solution) exhibited maximum fresh herbage yield (99 kg/plot) and dry matter yield (32 kg/plot) as compared to the control values of 68 kg/plot, and 23 kg/plot, respectively. Further, the treated plants possessed maximum total essential monoterpene oil(s) (2.3%) and geraniol (69%) as compared to control values of 0.66% and 57.3%, respectively. The positive significant correlation coefficient values between geraniol content and leaf area index (r = 0.941 ≤ = 0.01), and geraniol and dry matter content (r = 0.739 ≤ p = 0.01) suggested the increased availability of photosynthates and other precursor metabolites for enhanced growth and oil content. The data suggest that ethephon in synergistic treatment(s) of m-coumaric acid results into greater accumulation of endogenous ethylene in the anther leading to male sterility condition.

Effect of Application of Basic Slag and Superphosphate on Herbage Yield and on Soil and Herbage Concentrations of Phosphorus in Organic Grassland

ABSTRACT The experiment was carried out at an organic farm in 1996 and 1997. The purpose of the experiment was to test the effectiveness of basic slag (7% P) as a P fertilizer on an organic perennial ryegrass/white clover sward. Superphosphate (16% P) was used as a standard comparison. There was no difference between fresh weight or dry matter yields of grass or clover or of total herbage yields in plots treated with different rates of basic slag or superphosphate in the first harvest at the end of July 1996. In the second harvest, recorded at the end of August 1996, increasing rates of P gave increased yields. P source had no effect on herbage fresh weight or dry matter yield. P source and rate of P application had no effect on herbage yield in 1997. The percentage dry matter in herbage was unaffected by P source. Increasing rates of basic slag and superphosphate had no effect on the percentage dry matter in the herbage. There was no difference in the soil P concentrations obtained with basic slag or superphosphate when these were applied at equivalent rates. Increasing rates of P, when applied as basic slag or superphosphate at rates of 7, 14 and 28 kg ha−1, gave an increase in soil P concentration at 128 days after application. No increase was recorded at 531 days after application. Superphosphate gave the largest initial increase in herbage concentrations of P but was no more effective at raising the soil and herbage concentrations of this element than equivalent rates of basic slag over a two year period.

Sodium fertilizer application to pasture. 10. A comparison of the responses of dairy cows with high and low milk yield potential

Current recommendations for the intake of sodium of lactating dairy cows are related to milk yield. A study was conducted to compare the responses of cows of high and low milk production potential to the application of sodium fertilizer to grazed perennial ryegrass pasture. The application of sodium fertilizer increased the intake of herbage dry matter (DM), the time that cows spent grazing and the biting rate. It also increased the concentration of sodium, magnesium and calcium in herbage and decreased the concentration of potassium. Applying sodium fertilizer increased milk yield and milk fat concentration and decreased somatic cell count in the milk of cows of low‐production potential only, whereas it increased persistency of milk production in the cows of high‐production potential. The concentration of lactose in milk increased in both groups after the application of sodium fertilizer. It is concluded that the optimum dietary sodium concentration for grazing cows does not increase with milk yield, and that most immediate advantage will be gained from increasing the sodium concentration in herbage for low‐yielding cows.

The effect of sulphur application on the efficiency of nitrogen use in two contrasting grassland soils

The effect of sulphur (S) application on the efficiency of nitrogen (N) use was investigated using cut plot experiments on two contrasting soil types. Nitrogen was applied at 200 and 450 kg N/ha per year, with and without 38 kg SO3/ha (15·2 kg S/ha) per cut. Over three conventionally timed silage cuts for 2 years, measurements were made of herbage dry matter, the yield of N and S in herbage and losses of N and S by leaching, and N by denitrification.Herbage dry matter and N yields were significantly increased by the application of S at the high N level at the sandy loam site (Halse). At the clay loam site (Great Close) the application of S had no significant effect on herbage dry matter or N yields. At Halse, the pattern of response through the year was not the same in the 2 years studied, although in both, the effect of S was significant at third cut at high N. Deficiency was suggested by the N[ratio ]S ratio of herbage on the plots without S, especially at first cut, and at later cuts at Halse. Nitrate leaching was reduced by S at Halse by 72% and 58% with high N in 1997 and 1998, respectively, and by 10% and 5% on the low N treatments in 1997 and 1998, respectively. Application of S at high N at Halse reduced the peak concentration of nitrate-N in leachate from 27·3 mg N/l to 9·3 mg N/l. At Great Close, application of S had no significant effect on the amount or peak concentration of nitrate-N leached. The improvement in efficiency reported at Halse suggests that on permeable soils receiving high levels of N, the application of S could have a large effect on nitrate leaching and its associated environmental impact.

A comparison of three methods for measuring the vertical distribution of herbage mass in grassland

Three stratified clip methods for the estimation of herbage mass and its vertical distribution in grass swards were compared. The first method used a herbage‐gripping device, which held a sample from a 2 × 9 cm area while it was harvested and cut into layers in the field. For the other two methods, turfs of herbage were dug and brought into the laboratory where areas defined by 10 × 10 cm or 2 × 9 cm quadrats were cut into layers. For the comparisons, two operators collected independent samples from a sward shortly before it was cut for silage, a sward grazed by cattle and a sward grazed by sheep.The total mass of herbage dry matter collected depended on the method used, with the herbage‐gripping device producing greater estimates than the turf quadrats in two of the swards. The different methods produced similar estimates of the vertical distribution of mass. The larger quadrat usually produced the least variable results, while the herbage‐gripping device collected samples most quickly. There were also small differences between the estimates produced by different operators. It was concluded that because the herbage‐gripping device was the most cost‐effective it would often be the most appropriate method to use. However, when a higher level of precision per quadrat is required the large quadrat, following turf collection, would be more appropriate.

A comparison of two grassland‐based systems for autumn‐calving dairy cows of high genetic merit

A full lactation study compared the performance of autumn‐calving dairy cows of high genetic merit under two contrasting systems of milk production: high forage (HF) and high concentrate (HC). During the winter, animals on system HF were offered a silage with a high feeding value characteristics, supplemented with 5·5 kg of concentrate [crude protein content of 280 g kg−1 dry matter (DM)] through an out‐of‐parlour feeding system. From 14 March, these animals were given increasing access to grazing, achieving 24‐h turnout on 15 April. Thereafter, until day 305 of lactation, these animals were offered a large daily herbage allowance (23·0 kg grass DM cow−1, measured above a height of 4·0 cm), supplemented with 0·5 kg d−1 of a ‘high‐magnesium’ concentrate. During the winter, animals on system HC were offered a silage of medium feeding value, mixed with ≈14·0 kg of concentrate d−1 (crude protein content of 202 g kg−1 DM) in the form of a complete diet. These animals commenced grazing on 9 April, achieving 24‐h turnout on 18 April. From 18 April until 9 June, daily herbage allowances and concentrate feed levels were 17·0 kg DM and 5·0 kg respectively; thereafter, and until day 305 of lactation, these daily allowances were reduced to 15·0 kg of herbage DM and 4·0 kg of concentrate. Animal performance during the first 305 days of lactation for systems HF and HC, respectively, were as follows: total concentrate DM inputs, 842 and 2456 kg; total silage DM intakes, 2205 and 1527 kg; total grass DM intakes, 3019 and 2044 kg; total feed DM intake, 6061 and 6032 kg and total milk output, 7854 and 8640 kg. Total milk output per cow with system HF was 786 kg lower than for system HC, despite similar total DM intakes, suggesting a greater total nutrient requirement with the former to support a given milk production. However, the study confirms that relatively similar levels of animal performance can be achieved from systems based on very different sources of nutrient supply.

Prediction of silage feeding value from the analysis of the herbage at ensiling and effects of nitrogen fertilizer, date of harvest and additive treatment on grass silage composition

The prediction of silage feeding value from the analysis of herbage at ensiling and the effects of rate of nitrogen (N) fertilizer, date of harvest and treatment additive at ensiling on fermentation, dry matter (DM) recovery and effluent production were evaluated in a factorial experiment. Herbage was harvested from 75 plots, laid out in three replicate blocks of 25, from the primary growth of a predominantly perennial ryegrass sward. The plots received 72, 96, 120, 144 or 168 kg N/ha and were harvested on 10, 17, 24 or 31 May or 7 June. Herbage was ensiled for 176 days in laboratory silos (6 kg capacity), either untreated or treated with formic acid or a bacterial inoculant, each applied at 3 ml/kg herbage. Increasing the rate of N fertilizer and delaying harvest date increased herbage DM yield but decreased silage digestible organic matter digestibility (D-value) and intake potential (P < 0·001).Increasing the rate of N fertilizer increased crude protein (CP), acid insoluble N (AIN) (P < 0·001), acid detergent fibre (ADF) (P < 0·01) and acid detergent lignin (ADL) concentrations but had no statistically significant effect (P > 0·05) on pH or the concentrations of ammonia N, lactic or volatile fatty acids. Delaying harvesting date decreased CP, AIN and ADF concentrations (P < 0·001) and effluent DM losses (P < 0·001). Treatment with either formic acid or inoculant decreased silage pH and the concentrations of ammonia N, acetic acid and propanol and increased AIN, ethanol, neutral detergent fibre (NDF), ADF and cellulose concentrations, effluent volume, DM losses and intake potential. Formic acid treatment decreased D-value (P < 0·001), whereas inoculant treatment was not statistically significant (P > 0·05). For potential silage and metabolizable energy (ME) intakes and D- value, strong positive correlations (P < 0·001) were identified with herbage pH, buffering capacity and concentrations of CP, AIN, true protein nitrogen (TP), while negative correlations (P < 0·001) were identified with herbage yield and concentrations of NDF and hemicellulose. With untreated silages, strong positive correlations (P < 0·001) were identified between silage pH and herbage pH and concentrations of AIN, buffering capacity, ash, TP and negative correlations (P < 0·001) were identified with herbage DM yield and concentrations of DM and WSC. Herbage yield and concentrations of NDF, TP, DM and nitrate N provided the best linear relationship for predicting potential ME intake of the resultant untreated silages (R2 = 0·94). It is concluded that delaying harvest date had the most detrimental effect on silage feeding value, although this effect was partially overcome by reducing the rate of fertilizer N and use of either an inoculant or formic acid additive. Silage feed value was also highly correlated with the protein and fibre fractions, ash, buffering capacity and pH of the herbage at ensiling.

Short-term dietary effects on reproductive wastage after induced ovulation and artificial insemination in primiparous lactating Sarda ewes.

Short-term effects of nutrition on conception rate (CR), ovulation rate (OR), ova and embryo losses (OEL) during the first 50 days following insemination and total reproductive wastage after ovulation (TRW), were investigated in primiparous lactating Sarda ewes after oestrous synchronisation and cervical [corrected] artificial insemination (AI). Eighty ewes grazing a green high-quality pasture were offered one of three iso-energetic supplements from day 14 before to day 2 after AI: whole maize grain (M); soyabean meal (S); maize gluten meal (G); or served as controls (C). Supplements G and S were iso-nitrogenous but provided different amounts of rumen undegradable digestible protein. The intake of herbage and digestible dry matter, measured by the n560 mg/l was associated with lower CR. Ranking by ovulation groups of CR was single<double=triple; and of TRW was double<triple<single. In conclusion, OR in primiparous lactating Sarda ewes grazing on a good quality pasture is high, and CR after AI is reduced by ova as well as embryo loss, especially following single ovulations. Short-term supplementation with a soyabean-based concentrate may help alleviate these losses.

Intake of Cattle Offered Normal and Lodged Tall Fescue Swards

Grazing behavior of livestock may be altered when grass swards are lodged by trampling or wind and rain. We used a balanced change-over design to investigate the effects of lodging on the ingestive behavior of Angus cows (Bos taurus L.)(mass (M): 344 kg) grazing swards of vegetative endophytefree ‘Kenhy’ tall fescue ( Festuca arundinacea Schreb.). Animals were offered normal swards (T1), lodged swards (T2), or swards with one half of their area lodged (T 3 ). To simulate lodging, swards were covered overnight with weighted plywood sheets that compressed sward surface height (SSH) from 34 to 14 cm and elevated sward dry matter (DM) density from 151 to 499 kg ha -1 cm -1 for herbage > 5 cm. Mean herbage DM intake per bite was 561 mg for T1, 713 mg for T2 and 792 mg for T 3 . Cattle grazed at 28 bites min -1 for T 1 , and 25 bites min 1 for both T 2 and T3. Herbage DM intake rates were 0.27, 0.31, and 0.33 kg 100 kg -1 (M) hour -1 for T 1 , T 2 , and T 3 , respectively. In another experiment, cattle were offered equal areas of normal swards (SSH: 27 cm) and lodged swards (SSH: 16 cm), normal and partially defoliated swards (SSH: 20 cm) swards, or lodged and partially defoliated swards. When offered normal and lodged swards, 64% of DM intake came from normal swards. When offered normal and partially defoliated swards about 60% of DM intake came from normal swards. Cattle grazed equally on lodged and partially defoliated sward segments when offered that choice.

Endophyte Infection May Affect the Competitive Ability of Tall Fescue Grown with Red Clover

Cool-season grasses infected with Neotyphodium endophytes may be more persistent and competitive than non-infected plants. In a greenhouse experiment, two tall fescue (Festuca arundinacea Schreb.) cloned genotypes (DN2 and DN11) with different growth characteristics and endophyte status (E−, non-infected; E+, infected) were grown in monocultures and in full competition with red clover (Trifolium pratense L.) cv. Reddy Red for 20 weeks. When grown in monoculture, endophyte infection reduced the root dry matter (DM) of DN2 (16 %) and DN11 (5 %) when compared to E− plants, while shoot DM was not affected. In full competition with red clover, root and shoot DM of tall fescue were not influenced by endophytes, but cumulative herbage DM yield was less in E+ than in E− plants. Root growth of red clover was significantly depressed (22 %) in competition with E+ plants of DN2 compared to E− plants, but was not affected when plants were grown in competition with DN11. The relative yield total (RYT) did not differ from 1.0 in red clover mixtures with E− plants of DN2 and DN11, and with E+ plants of DN11, indicating competition between the competitors for the same resources. In contrast, RYT was less than 1.0 in the red clover/DN2 E+ mixture, suggesting a negative interaction between the competitors. Endophyte infection increased the competitive ability of DN2 but reduced that of DN11 when compared to E− plants. Because the concentration of pyrrolizidine alkaloids in roots of E+ plants of DN2 was twice that found in roots of DN11 (1083 and 536 μg g−1, respectively), we suggest that pyrrolizidine alkaloids might influence the competitive ability of some endophyte–tall fescue associations through a possible allelopathic effect on companion species.

Degradabilities of dry matter and crude protein from perennial herbage and supplements used in dairy production systems in Victoria

Summary The nylon bag technique was used to estimate the degradability of the dry matter (DM) and crude protein (CP) of herbage samples and supplementary feeds from recent grazing experiments with dairy cows conducted in Victoria. The cumulative disappearance data for CP were used to calculate the effective rumen degradability of CP (ERDP, g/kg DM) for these feeds at rumen outflow rates of 0.02, 0.05 or 0.08/h. Crude protein was more extensively degraded than DM in all herbage samples collected before grazing, or in those samples taken to represent the herbage consumed by grazing cows. The ERDP of spring pastures (excluding the dead material and postgrazed samples) was generally in the range 103–197 g/kg DM, at an outflow rate of 0.02/h and in the range 74–142 g/kg DM, at an outflow rate of 0.08/h. For summer pastures, the ERDP was generally in the range 80–128 g/kg DM, at an outflow rate of 0.02/h and in the range 58–108 g/kg DM, at an outflow rate of 0.08/h. For autumn pastures, ERDP ranged from 108 to 170 g/kg DM, at an outflow rate of 0.02/h and from 84 to 140 g/kg DM, at an outflow rate of 0.08/h. There were only 2 herbage samples collected during the winter, which had ERDP of 237 and 249 g/kg DM, at an outflow rate of 0.02/h and 213 and 222 g/kg DM, at an outflow rate of 0.08/h. Values for ERDP tended to be higher for these winter samples compared with spring samples. In contrast, autumn samples tended to have lower ERDP than spring samples. It is shown that metabolisable protein is unlikely to limit milk production of cows consuming 17 kg herbage DM/cow. day and producing up to 30 L milk/day, when milk production is determined from metabolisable energy supply. The excesses in metabolisable protein ranged from 0.48 to 1.21 kg/cow. day from a subset of spring herbage samples cut to represent that selected by cows and from 0.14 to 0.23 kg/cow. day from summer herbage samples. The degradability characteristics of the herbage samples were similar to some estimates for temperate herbages in the United Kingdom and from limited data from Australia and should form a useful basis on which to assess whether additional metabolisable protein is required as supplements for dairy cows grazing pastures in Victoria. There was a positive (P&lt;0.01) relationship between CP content and ERDP (R2 = 0.93), across herbage samples indicating it could be possible to estimate ERDP for herbage samples that have been assessed for CP content. There was also a significant (P&lt;0.01) positive relationship between the effective degradability of DM of herbage and ERDP (R2 = 0.77). The relationships between in vitro dry matter digestibility or neutral detergent fibre and ERDP were also significant (P&lt;0.01), but accounted for even less of the variability. The ERDP in cereal grain-based supplements ranged from 87 to 111 g/kg DM, at a outflow rate from the rumen of 0.02/h, compared with 70–92 g/kg DM, at an outflow rate of 0.08/h. The compounded supplements containing varying levels of cereal grain, lupins and cottonseed meal, had effective degradabilities of CP that generally declined as the content of lupins decreased and the content of cottonseed meal increased. However, ERDP increased to 152 g/kg DM because of the increasing CP content with increasing cottonseed meal. These results are compared with previously published estimates of effective degradability of CP for supplementary feeds.

Fall Seeding Date and Species Effects on Spring Forage Yield of Winter Cereals

A current research priority in short-season growing areas of Alberta is to increase cost efficiency of ruminant livestock production by extending the grazing season. The use of winter cereals is a potential source of earlier spring pasture than is provided by perennial grasses. This study determines the effect of fall seeding date on spring forage production of winter wheat (Triticum aestivum L.), fall rye (Secale cereale L.), and winter triticale (× Triticosecale Wittmack). One cultivar of each species (S) was seeded at Lacombe, AB, on 15 Aug., 1 Sept., and 15 Sept. in 1992 and 1993. Tiller and leaf numbers were recorded in the fall after dormancy. Spring clippings were taken when new growth was approximately 2 in. tall (as assessed by a disk height meter) and 1 wk later. Year and year × planting date effects were significant for most variables measured. Winter triticale and wheat were generally similar in treatment response while fall rye differed in some respects. Each delay of seeding resulted in smaller plants in the fall with fewer leaves and tillers. First clip yield varied from year to year, but was positively related to tiller or leaf number in the fall. Within the range of seeding dates used, earlier seeding produced earlier spring pasture. Fall rye tended to produce forage earlier and in greater quantity than the other two species. Dry matter yield generally increased linearly with increasing fall growing degree days (GDD) after planting. The use of early-planted fall rye for spring pasture in the western Parkland of the Canadian prairies is recommended. Research Question Alberta is a short-growing-season area where producers of ruminant livestock must feed conserved forage for 200 d or more each year. Extending the grazing season in spring or fall could have significant cost benefits for these producers. The feasibility of using spring-planted winter cereals either as monocrops or in mixtures with spring cereals has been demonstrated. It has been suggested that winter cereals may also provide alternative spring pasture to perennial grasses. The objective of this study was to determine the effects of seeding date on spring pasture production of three winter cereal species. Literature Summary Extension of the grazing season is a current research priority since significant cost savings to the livestock grazier can be effected. It has been shown that spring-planted winter cereals can be used to extend fall grazing and it has been suggested that fall-planted winter cereals may provide early spring pasture. Experiments relating to seeding date effects on winter cereals have confined observations to variables relating to grain production. It has been shown that optimum seeding dates differ for location according to climate and that deviation from this optimum, either earlier or later, generally results in yield reductions and some of the reasons have been explored. The effect of grazing on subsequent grain production has also been explored. There is little information on the effects of management practices on spring pasture production of winter cereals. Study Description This study was conducted for 2 yr at Lacombe, Alberta, Canada. Plots were seeded to ‘Norstar’ winter wheat, ‘Pika’ winter triticale, or ‘Muskateer’ fall rye on 15 August, 1 September, or 15 September each year. Fall observations included temperature and rainfall, time for crop emergence, and number of leaves and tillers produced per plant prior to winter dormancy. Spring weather records were kept from 1 April. The first clipping of plots occurred when crop canopy measured with a disk height meter was about 2 in. and a second followed 1 wk later. Herbage dry matter yields were determined. Crop growth stages, position of the growing point, and disk heights were recorded prior to each clipping. Applied Question Does seeding date for winter annual cereals affect spring pasture yield and earliness of usable pasture? Although year to year variations were large, earlier seeding generally produced higher yields and pasture was available earlier in the spring. Spring pasture yield showed a positive linear relationship to fall growing degree days. Do adapted winter cereal species differ in time and quantity of spring forage production or in response to fall seeding date? It appears that fall rye may have some advantage over winter triticale or winter wheat for spring forage production. In both years, rye produced harvestable forage earlier than the other two species. In one of the 2 yr, dry matter yields of rye were greater than the others. All species showed similar trends and relationships between seeding date and dry matter yield and harvest date. The growing point of rye remained below clipping height more consistently across clippings and seeding dates than the other species, which may allow a longer grazing period.