Clover Pasture Research Articles

Methane and carbon dioxide emissions from lactating dairy cows grazing mature ryegrass/white clover or a diverse pasture comprising ryegrass, legumes and herbs

There is a growing interest in forage mixtures (Diverse pasture; e.g. containing grasses, legumes and herbs), especially those with a greater tolerance of dry conditions and a decreased nitrogen (N) content (reducing N losses), compared with ryegrass (Lolium perenne L and Lolium multiflorum L)/white clover (Trifolium repens L) pastures (RyeWC), which dominate New Zealand pastoral systems for dairy production. However, the effect of alternative forages on enteric methane (CH4) emissions is not known. The objective of the present trial was to compare CH4 emissions and milk production from dairy cows grazing either mature RyeWC or mature Diverse pasture (both approximately with pasture mass of 5600 kg DM/ha). The Diverse mixture comprised ryegrass, white clover, lucerne (Medicago sativa L), chicory (Cichorium intybus L) and plantain (Plantago lanceolata L). Milk production, measured from cows commencing at ~162 days of lactation, was less when cows grazed RyeWC than Diverse pastures (15.4 vs 16.7 kg/day; P < 0.001), whereas CH4 production (g/day) was similar for the respective treatments (411 g/day; P = 0.16). Milk composition was not affected by diet and CH4 intensity was similar for both diets (22 g/kg fat- and protein-corrected milk; P = 0.31). Methane yield [g/kg predicted dry matter intake (DMI)] averaged 22.6 and 24.9 for cows grazing RyeWC and Diverse pastures, respectively (P = 0.006). In conclusion, although the CH4 yield was greater when Diverse pasture was grazed, relative to RyeWC, there were no differences in emissions intensity or total CH4 emissions.

Effect of repeated trace mineral injections on beef heifer development and reproductive performance.

To determine the effects of repeated trace mineral injections on heifer development and reproductive performance, commercial Angus heifers (n = 290; 199 ± 34.3 kg; 221 ± 22 d of age) were utilized in a completely randomized design. Heifers were stratified by body weight (BW) and were administered an injectable trace mineral (MM; Multimin 90) or saline (CON) given subcutaneously, post-weaning at 221, 319, 401, and 521 ± 22 d of age. Throughout development, heifers grazed endophyte-infected fescue, red clover pastures and were supplemented with corn distillers grains (2.7 kg per heifer per day) and given access to free choice inorganic minerals. Heifer BW and body condition scores (BCS) were collected at trial initiation and 4- to 7-wk intervals thereafter. Hair coat scores (HCS) and respiration rates (n = 30 heifers per treatment) were collected at 269, 310, and 361 ± 22 d of age. Blood and liver samples were collected at trial initiation and estrous synchronization from 30 heifers per treatment to determine trace mineral status. At 319, 372, and 421 ± 22 d of age, antral follicle count and ovarian size were determined via ultrasonography. Two blood samples from all heifers were collected 10 d apart, concurrent with ultrasound dates, for cyclicity determination. Estrous synchronization was initiated, and reproductive tract scores (RTS) were collected at 421 ± 22 d of age, and heifers were bred via artificial insemination (AI) at 430 ± 22 d of age. Heifer BW, BCS, and HCS did not differ (P ≥ 0.12) throughout development, except at 268 ± 22 d of age when BCS was greater (P = 0.03) for MM than CON heifers. Respiratory rates were greater (P = 0.05) for MM than CON heifers at 269 ± 22 d of age but did not differ (P ≥ 0.66) at 310 and 361 ± 22 d of age. Plasma Mn and Zn concentrations did not differ (P ≥ 0.54). However, MM heifers had greater (P ≤ 0.01) plasma and liver concentrations of Cu and Se compared to CON. Interestingly, MM decreased (P = 0.02) liver Zn concentrations compared to CON, and there was no difference (P = 0.60) in liver Mn. Antral follicle count and ovarian size did not differ (P ≥ 0.51) due to treatment. Throughout development, number of heifers cycling was lesser (P < 0.01) for MM than CON heifers. However, there was no difference (P ≥ 0.19) in RTS, AI pregnancy rates, or overall pregnancy rates. Supplementing an injectable trace mineral increased heifer Cu and Se status; however, no effect was noted on ovarian development or pregnancy rates.

Oat silage for grazing dairy cows in small-scale dairy systems in the highlands of central Mexico

The objective was to evaluate the provision of oat silage (Avena sativa) to supplement grazing dairy cows on pastures of perennial ryegrass (Lolium perenne), festulolium (Lolium multiflorum × Festuca pratense) and white clover (Trifolium repens) during the dry season when pasture growth is limited. The experimental design was a 3 × 3 Latin square replicated three times, with nine milking Holstein cows (mean live weight 496.2 ± 33.6 kg and daily milk yield 14.8 ± 2.8 kg cow−1) under on-farm participatory rural research. Experimental periods were 14 d. Simulated grazing samples of pasture herbage were analysed for chemical composition, sward height recorded and net herbage accumulation determined from exclusion cages. Treatments were the inclusion of oat silage at T0 = 0 kg DM cow−1 d−1 of oat silage, T3 = 3 kg DM cow−1 d−1 of oat silage, and T6 = 6 kg DM cow−1 d−1 of oat silage, plus 5.0 kg fresh weight commercial concentrate and 9 h of continuous grazing. Animal variables were milk yield and composition, live weight and body condition score. Feeding costs were calculated. Mean milk yield was 18.9 ± 0.27 kg cow−1 d−1 with no differences in animal variables (p > 0.05), but feeding costs per kilogram milk increased 25% for T3 and 50% for T6. Oat silage supplementation is only viable under difficult grazing conditions.

Milk yield and urinary-nitrogen excretion of dairy cows grazing forb pasture mixtures designed to reduce nitrogen leaching

The effect of including a mixture of forbs in a standard perennial ryegrass-white clover pasture, with or without Italian ryegrass was investigated in a two-period grazing study comparing urinary nitrogen (N) excretion and milk yield of dairy cows in late lactation. Forty-eight mixed age, Holstein Friesian x Jersey cows were assigned to replicated, balanced, groups of six and offered one of four pasture treatments. Pasture types were either a perennial ryegrass-based pasture (PRG) with white clover or a forb-containing mixed pasture (MIX) including perennial ryegrass, white clover, chicory, plantain and lucerne. A second factor was the inclusion of Italian ryegrass (PRG+I and MIX + I). During Period I, ten cows in each of the MIX and PRG treatments were fitted with urine sensors to measure urine N parameters (urination frequency, volume and N concentration). During Period II, milk yield was measured from cows on all four pasture types. In both the ryegrass and forb pasture types, legume content exceeded 30% of the DM and in forb pastures chicory and plantain accounted for over 30% of the DM. Italian ryegrass in the MIX + I and PRG+I was respectively 5% and 15% of the DM. Digestibility and crude protein was similar for all pasture types, but fibre content was lower for forb pastures. During Period I, there was no effect of pasture type on the amount of N per urination event (averaged 13gN/event) and daily urine-N excreted (190gN/cow/day). However, pasture type affected the diurnal pattern in urine-N excretion with MIX pastures having a lower urine N loading per event during the day and higher urine N loading at night compared with PRG pastures. During Period II, milk yield was greater for forb compared with ryegrass pasture types (1.66 vs 1.50kg MS/cow/d). There was no effect of Italian ryegrass on milk yield due to low botanical content. This study demonstrated that forb containing pastures altered the diurnal pattern in urine-N excretion and offers opportunities to mitigate N leaching from grazed pastures whilst supporting high milk production in late lactation.

Supplementation of dairy cows with commercial concentrate or ground maize grain under cut-and-carry or grazing of cultivated pastures in small-scale systems in the highlands of central Mexico

Small-scale dairy systems (SSDS) in Mexico represent over 78% of dairy farms and 37% of milk production. In the central highlands, many SSDS base the feeding of herds on irrigated cultivated pastures (mostly cut-and-carry), straws, and large amounts of commercial concentrates that result in high feeding costs and low economic sustainability. Intensive grazing may result in lower feeding costs when compared with cut-and-carry strategies. The high protein content of pasture may meet requirements of dairy cows with moderate milk yield (16–20 kg milk/cow.day), so that lower protein supplements, like ground maize grain, may substitute for commercial concentrates. An on-farm experiment following a participatory rural research approach was undertaken with seven farmers evaluating commercial concentrate (CC) or ground maize grain (MG) as supplement; and two pasture managements, grazing (G) or cut-and-carry (C) of irrigated ryegrass/white clover pastures to assess productive performance and feeding costs. Six farmers participated with four milking cows each and one farmer with two groups of four milking cows in a 2 by 2 factorial experiment. Daily milk yield per cow before the experiment was used as covariate. The experiment lasted 12 weeks. There is a trend in G for higher protein content in milk (P &amp;lt; 0.10). CC showed higher body condition score than MG with a significant interaction for body condition score with the highest body condition score in CCC (P &amp;lt; 0.05). Feeding costs were 15% higher per kg of milk yield and 19% per kg of energy-corrected milk under cut-and-carry but no statistical differences were detected (P &amp;gt; 0.05) in comparison with the grazing strategy. Supplementing with home-grown ground maize grain resulted in 28.5% higher margins per kg of milk produced. Implementing grazing involves less work burden for small-scale dairy farmers, and combined with home-grown grains as supplement is a viable option that may reduce feeding costs in these systems.

Ex-vivo cow rumen fluid fermentation: changes in microbial populations and fermentation products with different forages

ABSTRACTThis study investigated the effects of three forage treatments [herbal plantain (PL), ryegrass-white clover pasture (RW) and root crop fodder beet (FB)] on ex-vivo rumen fluid fermentations. Quantitative real-time Polymerase Chain Reaction (qPCR) and PCR-single-stranded conformation polymorphism (PCR-SSCP) analyses were undertaken for aliquots collected from the fermentations. The FB treatment had the highest volatile fatty acid (VFA) and lowest pH compared with other treatments. The RW culture that had a higher fibre content, had higher Fibrobacter succinogenes(F. succinogenes) and anaerobic fungi levels when compared with the FB and PL. Protozoans were however the most abundant microorganisms in the FB cultures, and they had the highest water-soluble carbohydrate (WSC) content. The abundance of F. succinogenes increased in the RW fermentation up to 12 h, and the abundance of anaerobic fungi increased in the RW fermentation up to 24 h. In all the treatments, no effect was found on the overall abundance of bacteria. The findings confirmed that changes in rumen microbial community and fermentation products are partly related to the WSC and fibre content of two novel forages (i.e. PL and FB) increasingly used in animal production.

Live weight gain, animal behaviour and urinary nitrogen excretion of dairy heifers grazing ryegrass–white clover pasture, chicory or plantain

ABSTRACTThe objective of this study was to assess live weight gain, animal behaviour and N excretion in the urine of dairy heifers fed herbs during autumn and spring. Sixty heifers were allocated into five dietary treatments: 100% ryegrass–white clove pasture (100RG/WC); 50% RG/WC + 50% chicory (50CH); 75% RG/WC + 25% chicory (25CH); 75% RG/WC + 25% plantain (25PL); and 50% RG/WC + 50% plantain (50PL). The 100RG/WC had the highest (5.0 times/6 h) and lowest (2.5 times/6 h) urination frequency compared with other treatments in autumn (averaged 3.5 times/6 h) and spring (averaged 4.5 times/6 h), respectively. The heifer LWG in spring was higher in 25CH (1.36 kg/day) than other treatments (averaged 1.10 kg/day). Urinary N concentration was 0.18% and 0.23% in autumn and spring, respectively, across treatments, with no difference between treatments. The study demonstrated inconsistent results of use of chicory and plantain as a mitigation tool to reduce the environmental impact of heifer rearing systems in autumn and spring.

Outdoor grazing of dairy cows on pasture versus indoor feeding on total mixed ration: Effects on gross composition and mineral content of milk during lactation

The influence of feeding system and lactation period on the gross composition, macroelements (Ca, P, Mg, and Na), and trace elements (Zn, Fe, Cu, Mo, Mn, Se, and Co) of bovine milk was investigated. The feeding systems included outdoor grazing on perennial ryegrass pasture (GRO), outdoor grazing on perennial ryegrass and white clover pasture (GRC), and indoors offered total mixed ration (TMR). Sixty spring-calving Holstein Friesian dairy cows were assigned to 3 herds, each consisting of 20 cows, and balanced with respect to parity, calving date, and pre-experimental milk yield and milk solids yield. The herds were allocated to 1 of the 3 feeding systems from February to November. Milk samples were collected on 10 occasions over the period June 17 to November 26, at 2 or 3 weekly intervals, when cows were on average 119 to 281 d in lactation (DIL). The total lactation period was arbitrarily sub-divided into 2 lactation periods based on DIL, namely mid lactation, June 17 to September 9 when cows were 119 to 203 DIL; and late lactation, September 22 to November 26 when cows were 216 to 281 DIL. With the exception of Mg, Na, Fe, Mo, and Co, all other variables were affected by feeding system. The GRO milk had the highest mean concentrations of total solids, total protein, casein, Ca, and P. The TMR milk had the highest concentrations of lactose, Cu, and Se, and lowest level of total protein. The GRC milk had levels of lactose, Zn, and Cu similar to those of GRO milk, and concentrations of TS, Ca, and P similar to those of TMR milk. Lactation period affected all variables, apart from the concentrations of Fe, Cu, Mn, and Se. On average, the proportion (%) of total Ca, P, Zn, Mn, or Se that sedimented with the casein on high-speed ultracentrifugation at 100,000 × g was ≥60%, whereas that of Na, Mg, or Mo was ≤45% total. The results demonstrate how the gross composition and elemental composition of milk can be affected by different feeding systems.

Milk production and urinary nitrogen excretion of dairy cows grazing plantain in early and late lactation

ABSTRACTThe effects of 50% or 100% of a herbage diet of plantain on milk production and urinary nitrogen (N) concentration were measured in two experiments for late (autumn 2015) and early (spring 2015) lactation dairy cows. Three groups of 12 mixed age Friesian × Jersey dairy cows were offered a perennial ryegrass-white clover pasture, or pure plantain or 50% perennial ryegrass-white clover and 50% pure plantain by ground area (50–50 pasture–plantain). Urine N concentration was lower in both experiments (P < .001) for plantain (2.4 and 2.2 g N/L) and 50–50 pasture–plantain (3.6 and 3.4 g N/L) than pasture (5.4 and 4.7 g N/L). Cows on plantain or 50–50 pasture-plantain produced at least as much milk as those on pasture in both experiments. Plantain may offer environmental benefits to dairy systems by reducing the N concentration of urine deposited on the soil from grazing cows.

637 Effect of repeated trace mineral injections on beef heifer development and reproductive performance

To determine the effects of repeated trace mineral injections on heifer development and reproductive performance, commercial Angus heifers ( n = 290; 199 ± 34.3 kg) were utilized in a completely randomized design. Heifers were stratified by BW into 6 groups and assigned to injectable trace mineral (MM; Multimin90) or saline injection (CON) given post-weaning at 221, 319, and 401 ± 22 d of age. Throughout development, heifers grazed endophyte-infected fescue-red clover pastures and were supplemented with modified corn distillers grains (2.7 kg·heifer-1·d-1) and given access to free choice inorganic minerals formulated to meet or exceed NRC recommendations. Heifer BW and BCS were collected at trial initiation and 4-7 week intervals thereafter. Hair coat scores (HCS) and respiration rates (n = 30 heifers/treatment) were collected at 269, 310, and 361 ± 22 d of age. Additionally, blood and liver samples were collected at trial initiation and estrous synchronization from 30 heifers/treatment to determine trace mineral status. At 319, 372, and 421±22 d of age, antral follicle count and ovarian size were determined via ultrasonography. Two blood samples from all heifers were collected 10 d apart, concurrent with ultrasound dates, for puberty determination. Estrous synchronization was initiated and reproductive tract scores (RTS) were collected at 421±22 d of age. Heifers had AI at 430 ± 22 d of age. Heifer BW, BCS, and HCS did not differ (P ≥ 0.12) throughout development, except at 268 ± 22 d of age when BCS was greater (P = 0.03) for MM than CON. Respiratory rates were greater (P = 0.05) for MM than CON at 269±22 d of age, but did not differ (P ≥ 0.66) at 310 and 361 ± 22 d of age. Plasma Mn and Zn concentrations did not differ between treatments (P ≥ 0.54). However, MM had greater (P ≤ 0.01) plasma and liver concentrations of Cu and Se compared to CON. Interestingly, MM decreased (P = 0.02) liver Zn concentrations compared to CON and there was no difference (P = 0.60) in liver Mn concentrations. Antral follicle count and ovarian size did not differ (P ≥ 0.43) between treatments. Throughout development, the number of pubertal heifers was less (P < 0.01) for MM than CON. However, there was no difference (P ≥ 0.26) in RTS or AI pregnancy rates (36 and 37% for MM and CON, respectively). Supplementing an injectable trace mineral increased heifer Cu and Se status; however, no effect was noted on ovarian development or reproductive performance.

Pasture damage from spot-sprayed herbicides

Spot-spraying weeds in pastures enables the use of herbicide that would be too harmful to pasture if boom-sprayed. However, some herbicides are more damaging than others. To quantify this damage, a range of spot-spraying treatments was applied to ryegrass/white clover pastures. Four herbicide treatments were compared, each at two application rates and two sizes of sprayed patch. Applications of either clopyralid or a triclopyr/picloram mix resulted in total removal of white clover from the sprayed patches but these patches remained covered in perennial ryegrass. Metsulfuron also removed all white clover but also severely damaged the perennial ryegrass, although some grass cover remained due to survival of browntop. Residues of these treatments suppressed seedlings of white clover and weeds for many weeks after application. Glyphosate treatments resulted in the most bare soil. White clover recovered most rapidly in glyphosate-treated areas, mainly by lateral spread of stolons, but weed species also established rapidly.

Effect of pasture versus indoor feeding systems on quality characteristics, nutritional composition, and sensory and volatile properties of full-fat Cheddar cheese.

The purpose of this study was to investigate the effects of pasture-based versus indoor total mixed ration (TMR) feeding systems on the chemical composition, quality characteristics, and sensory properties of full-fat Cheddar cheeses. Fifty-four multiparous and primiparous Friesian cows were divided into 3 groups (n = 18) for an entire lactation. Group 1 was housed indoors and fed a TMR diet of grass silage, maize silage, and concentrates; group 2 was maintained outdoors on perennial ryegrass only pasture (GRS); and group 3 was maintained outdoors on perennial ryegrass/white clover pasture (CLV). Full-fat Cheddar cheeses were manufactured in triplicate at pilot scale from each feeding system in September 2015 and were examined over a 270-d ripening period at 8°C. Pasture-derived feeding systems were shown to produce Cheddar cheeses yellower in color than that of TMR, which was positively correlated with increased cheese β-carotene content. Feeding system had a significant effect on the fatty acid composition of the cheeses. The nutritional composition of Cheddar cheese was improved through pasture-based feeding systems, with significantly lower thrombogenicity index scores and a greater than 2-fold increase in the concentration of vaccenic acid and the bioactive conjugated linoleic acid C18:2 cis-9,trans-11, whereas TMR-derived cheeses had significantly higher palmitic acid content. Fatty acid profiling of cheeses coupled with multivariate analysis showed clear separation of Cheddar cheeses derived from pasture-based diets (GRS or CLV) from that of a TMR system. Such alterations in the fatty acid profile resulted in pasture-derived cheeses having reduced hardness scores at room temperature. Feeding system and ripening time had a significant effect on the volatile profile of the Cheddar cheeses. Pasture-derived Cheddar cheeses had significantly higher concentrations of the hydrocarbon toluene, whereas TMR-derived cheese had significantly higher concentration of 2,3-butanediol. Ripening period resulted in significant alterations to cheese volatile profiles, with increases in acid-, alcohol-, aldehyde-, ester-, and terpene-based volatile compounds. This study has demonstrated the benefits of pasture-derived feeding systems for production of Cheddar cheeses with enhanced nutritional and rheological quality compared with a TMR feeding system.

Direct recovery of 33 P-labelled fertiliser phosphorus in subterranean clover ( Trifolium subterraneum ) pastures under field conditions – The role of agronomic management

Abstract Grazing systems are a major producer of food and fibre across the world. These systems often require the addition of fertiliser phosphorus (P) for maximum pasture growth, and it is now estimated that a four-fold increase in the use of P fertiliser in grasslands is needed to meet increased food demand by the year 2050. However, the recovery of P from fertiliser is often inefficient and global issues associated with P scarcity will continue to worsen. Knowledge on the uptake of fertiliser P by grasslands, including the effect of agronomic management, remains incomplete under field conditions. The aim of this study was to quantify the effects of soil P fertility (across three levels of soil P fertility), time of fertiliser application (at one level of soil P fertility), and placement of fertiliser (at one level of soil P fertility) on the growth and uptake of fertiliser P by clover pastures during a growing season. Subterranean clover (Trifolium subterraneum L.) monocultures established at two field sites in Australia were used to test the growth response to, and recovery of: (i) early-season (autumn) additions of fertiliser P to the soil surface at three levels of soil P fertility; (ii) mid-season (late winter) additions of fertiliser P to the soil surface; and (iii) early-season additions of fertiliser P placed 6 cm below the soil surface. Fertiliser P was applied to the pastures as single superphosphate that was labelled with a 33P radiotracer to supply ∼20 kg P ha−1. Total herbage yield and recovery of fertiliser P by the clover pastures was generally highest when fertiliser P was applied to the soil surface early in the growing season and to soils maintained at the optimum level of soil P fertility for maximum pasture growth. An audit of the 33P recovery of fertiliser P in the clover pasture revealed that up to 50% of the fertiliser P was recovered by the clover plant (shoots and roots), 5–15% remained in the fertiliser granule, and 20–25% was recovered in the 0–4 cm soil layer (largely as inorganic P) by the end of the growing season. We demonstrate that clover pastures are able to recover a relatively large proportion of surface applied fertiliser P during a growing season. Surface application is the simplest and most cost-effective strategy for management of fertiliser P in pastures.

Environmental factors determine severity of Rhizoctonia damping-off and root rot in subterranean clover

This study defines the importance of environmental conditions occurring across southern Australian subterranean clover (Trifolium subterraneum) forages on the severity of Rhizoctonia (Rhizoctonia solani) damping-off and root rot and on consequent plant productivity. Environmental factors tested included temperature regimes 14/9; 18/13 and 22/17 °C day/night, high vs. low soil moisture; sand vs. loam soil; high vs. low nutrition, and clover cultivars Riverina, Seaton Park and Woogenellup. Environmental factors significantly affected the severity of damping-off, root disease and root and shoot productivity. Damping-off was at or close to 100% at the two cooler of the three temperature regimes. At the warmest of the three temperature regimes (22/17 °C), significant numbers of subterranean clover plants germinated and survived, and germination, dry root and shoot weights all increased conversely with decreased tap and lateral root disease under higher moisture, better nutrition and under ‘heavier’ soil conditions. Findings demonstrate how variations in environmental factors like temperature in particular, but also soil type, nutrition, moisture, individually and interacting, have profound effects on the expression and severity of Rhizoctonia damping-off and root disease and the consequent productivity of subterranean clover forages. Findings explain the severe devastation to subterranean clover pastures observed in the presence of this pathogen when cool seasonal conditions occur across the critical autumn feed-gap period; especially under relatively drier soil conditions and in nutritionally impoverished sandy soils where there is little competition from other soil microbes.

The effects of feeding cut plantain and perennial ryegrass-white clover pasture on dairy heifer feed and water intake, apparent nutrient digestibility and nitrogen excretion in urine

Urinary nitrogen concentration (UNcc) and urinary N excretion (UN) are directly associated with the nitrogen (N) leaching potential of soil and greenhouse gas emissions from grazing ruminants’ urine patches. This study was carried out to examine the effects of feeding cut plantain (PL) and perennial ryegrass-white clover pasture (PW) on dairy heifer feed and water intake, apparent nutrient digestibility and N excretion in urine. Twelve Jersey-Friesian heifers aged 9–10 months with an average body weight of 200±18.8kg (mean±standard deviation (SD)) and breeding worth of NZ$162±16.9 (mean±SD) were randomly allocated to one of two treatments (six heifers per treatment): PW and PL. No difference was observed in dry matter intake (P=0.117) and N intake (P=0.370) between PW- and PL-fed heifers. The dry matter digestibility and digestible organic matter in the dry matter were similar between PL- and PW-fed heifers (P>0.05). Heifers consuming PL had lower UNcc and UN than those consuming PW (P<0.01). Estimated urine volume and total water intake were higher for PL-fed heifers than those fed PW (P<0.01). Further, in comparison with PW-fed heifers, PL-fed heifers had lower plasma urea N (P<0.001) and tended to have lower plasma δ15N – feed δ15N (P=0.086). The findings suggest that feeding PL to dairy heifers may reduce UNcc and UN in comparison with those on conventional pastures; therefore it provides an opportunity to mitigate on-farm N pollution.

Seasonal changes in the digesta-adherent rumen bacterial communities of dairy cattle grazing pasture.

The complex microbiota that resides within the rumen is responsible for the break-down of plant fibre. The bacteria that attach to ingested plant matter within the rumen are thought to be responsible for initial fibre degradation. Most studies examining the ecology of this important microbiome only offer a ‘snapshot’ in time. We monitored the diversity of rumen bacteria in four New Zealand dairy cows, grazing a rye-grass and clover pasture over five consecutive seasons, using high throughput pyrosequencing of bacterial 16S rRNA genes. We chose to focus on the digesta-adherent bacterial community to learn more about the stability of this community over time. 16S rRNA gene sequencing showed a high level of bacterial diversity, totalling 1539 operational taxonomic units (OTUs, grouped at 96% sequence similarity) across all samples, and ranging from 653 to 926 OTUs per individual sample. The nutritive composition of the pasture changed with the seasons as did the production phase of the animals. Sequence analysis showed that, overall, the bacterial communities were broadly similar between the individual animals. The adherent bacterial community was strongly dominated by members of Firmicutes (82.1%), followed by Bacteroidetes (11.8%). This community differed between the seasons, returning to close to that observed in the same season one year later. These seasonal differences were only small, but were statistically significant (p < 0.001), and were probably due to the seasonal differences in the diet. These results demonstrate a general invariability of the ruminal bacterial community structure in these grazing dairy cattle.

Herb and clover mixes for New Zealand sheep and cattle grazing systems

Perennial ryegrass/white clover (rye/wc) pasture provides the predominate pasture source for sheep and beef cattle farming systems in New Zealand. However, during summer limited rainfall often results in soil moisture deficits and when combined with high air temperatures, rye/wc can have low growth rates and be of poor quality. Farmers are sowing summer active perennial herb and clover mixes in order to combat this problem and improve animal performance. This article describes the pasture yield and quality attributes of herb and clover mixes, the potential improvement to animal performance and the optimum grazing management regimen necessary to maximise both the pasture and animal performance.

Cultivation offers effective management of subterranean clover damping‐off and root disease

AbstractSoil cultivation studies involving subterranean clover pastures were undertaken utilizing field cores from five farms and two in‐field trials. Tap and lateral root disease in cores was less (p &lt; .001) severe and root and shoot weights greater (p &lt; .001) following simulated cultivation. Germination and severity of root disease were both affected (p &lt; .005) by three‐way interactions with cultivation, cultivar and field site. Cultivation in cores suppressed tap root disease for cultivars Meteora and Riverina across the five sites and Seaton Park for two sites. In‐field trials confirmed cultivation reduces root disease severity and increases germination and plant productivity. The best in‐field treatment was cultivation + fumigation that reduced (p &lt; .05) tap and lateral root disease and increased nodulation and root and shoot weights for Riverina, Seaton Park and Woogenellup. Cultivation + fumigation also increased (p &lt; .05) germination for Woogenellup and Seaton Park. There were negative correlations (all p &lt; .001) between tap and lateral root disease with nodulation (R2 = .85, R2 = .58, respectively); tap root disease with root and shoot weight (R2 = .58, R2 = .854, respectively); and lateral root disease with root and shoot weight (R2 = .83, R2 = .64 respectively). This study highlights the close relationship between severe root disease and reduced nodulation, likely explaining much of the widespread poor nodulation in subterranean clover pastures. This study confirms that damping‐off and root disease can be mitigated by cultivation, offering producers flexibility in disease management, especially where autumn–winter feed shortages occur on a regular basis.

Turning knowledge into practical benefit: a producer case-study increasing the return on investment in science

The present paper addresses turning knowledge into practical benefit; acknowledging a critical emphasis of the career of John L. Black. Average efficiency of pasture use by beef enterprises in southern Australia is historically ~35%. Two projects established in 2002 showed that the efficiency of pasture use could approach 90% and the conservative rates observed were due to a low adoption of existing knowledge and the perceived risks from intensification. A risk-control management system, ‘More Beef from Pastures’, was developed from these projects, to identify management practices that had the largest impacts on productivity and profitability, the variables that needed to be measured and the upper and lower limits for those measurements to optimise enterprise performance. The principles from that system were incorporated into a productivity and economic spreadsheet model for a beef enterprise near Blayney on the Central Tablelands of New South Wales. The present paper reports the effects on productivity and profitability of several management scenarios, including current practice with 180 breeding cows and progeny sold in the second year after birth; buying and selling steers; making silage; or combinations of steers and silage, to maintain pasture availability between 1200 and 2600 kg DM/ha. Simulations were conducted for rainfall and growth of a phalaris–subterranean clover pasture predicted for the Blayney climate by the Sustainable Grazing Systems model for the Years 2000–2011. The simulations covered eight consecutive years from 2002 to 2009, when mean pasture growth was only 70% of the average. Results from the simulations for current practice were similar to those observed for the enterprise. The simulations showed the importance on profitability of utilising excess pasture in years of high pasture growth. The highest average profitability across years resulted from the scenario involving purchase and sale of steers, but year-to-year fluctuations were large and significant capital was required. The silage and steer-silage scenarios were intermediate in profitability, and depended on initial silage reserves and numbers of breeding cows. The exercise demonstrated that a simple spreadsheet model based on principles of animal nutrition, pasture management and economics was needed to fully evaluate alternative management strategies for practical benefit on existing beef enterprises.

Interaction of diet and long ageing period on lipid oxidation and colour stability of lamb meat

Eighty-four crossbred wether and ewe lambs were allocated to four finishing diets. The diets were: Lucerne pasture (n=24), Annual ryegrass with sub clover pasture (n=18), Standard commercial feedlot pellets (n=24) and Annual ryegrass based pasture and commercial feedlot pellets (500g/day/head) (n=18). After 8weeks of feeding the lambs were slaughtered and the m. longissimus (LL) and m. semimembranosus (SM) were vacuum packaged and held chilled for 5 (fresh) or 60 (long aged) days, after which samples of each were displayed for 4days under simulated retail conditions. Irrespective of muscle type the long aged samples exhibited a rapid reduction in redness (a*-values) and R630/580nm ratio values such that consumer acceptable thresholds for both traits were quickly exceeded providing limited shelf life. Long ageing also lead to high TBARS levels measured as MDA mg/kg muscle suggestive of a product likely to exhibit rancidity and off flavours from lipid oxidation.