Response of simple grass-white clover and multi-species pastures to gibberellic acid or nitrogen fertiliser in autumn

Herbage dry matter (DM) production, botanical composition and nutritive value of pastures were measured in response to the application of 24 g/ha gibberellic acid (GA; 60 g ProGibb®/ha) and 50 kg N/ha nitrogen fertiliser (N; 106 kg urea/ha) in autumn. Responses were compared for simple two species grass (perennial ryegrass or tall fescue)-white clover pastures and multi-species pastures where herbs (chicory and plantain), legumes (red clover and lucerne) and prairie grass were sown with the simple mixtures. Four weeks after application, the increase in DM yield averaged across pasture mixtures relative to untreated plots was 273, 104, and 493 kg DM/ha for GA alone, N fertiliser alone, and GA and N combined, respectively. Application of GA increased the white clover percentage in all pastures except simple tall fescue pastures. The percentage of herbs in multispecies pastures was increased by application of N but not GA. Crude protein concentration was decreased by GA application in all pastures except simple ryegrass pastures. The results from this study show that it is important to consider the botanical composition of pastures when determining the effect of GA on DM yield and nutritive value

Liveweight gain per head and per ha throughout the year of lambs grazing conventional pastures and those that switch from grass to clover

Intensive lamb finishing requires a consistent supply of high quality forage throughout the year to regularly finish lambs. Per head and per ha liveweight gain of weaned lambs was compared in 13 batches of lambs on replicated irrigated farmlets for 2.5 years from conventional mixed tetraploid perennial ryegrasswhite clover pastures (Conv) and pastures that were pure white clover for spring and summer and switched to overdrilled Italian ryegrass for the winter (Switch). Seasonal differences in stocking rate (lambs/ha), liveweight gain per head and per ha were significant (P<0.05). Average daily liveweight gain/ha was significantly higher (6.01 versus 5.66 kg/ha/day for Switch and Conv, respectively, but the total grazing days were slightly lower on the Switch farmlets resulting in similar annualised liveweight gain per ha (1 800 kg) and net carcass weight (800 kg/ha) on both pasture treatments. The farmlets apparently utilised 10 000 kg DM/ha/yr of the 16 000 kg DM accumulated.This work was funded by an internal Lincoln University Research Grant INT4052

Argentine stem weevil damage to high sugar ryegrass infected with AR1 under field conditions

Previous laboratory based studies indicate that, compared to standard cultivars, high sugar grasses (HSG) can have lower endophyte and peramine concentrations and suggest that N fertilisation may result in further reductions in endophyte and alkaloid. This could reduce the resistance of HSG, particularly at high N inputs, to Argentine stem weevil (ASW), but the interaction needs testing under field conditions. The present objective was to determine the effect of ryegrass cultivar on ASW damage, and possible interactions with N fertiliser. ASW damage, endophyte and peramine concentration were measured in three perennial ryegrass cultivars, (HSG diploid, standard diploid and a tetraploid) containing AR1 endophyte, under high and no N fertiliser application. The proportion of tillers damaged by ASW adults or larvae did not differ significantly between cultivars. However, ASW adults tended (P<0.10) to prefer the standard diploid and tetraploid cultivars over the HSG cultivar. Our results are in keeping with previous observations that higher sugar diploid cultivars may have lower endophyte and peramine content than a STD diploid cultivar, but this does not appear to have reduced resistance to ASW. Lack of differences in N content of herbage leaves, between the N fertiliser treatments, likely due to compensating changes in clover content of pastures, meant little effect of N application was seen in this field trial

Relationship between social dominance and milk production of dairy cows grazing pasture

The objectives of this experiment were to study factors determining social dominance of grazing dairy cows and the relationship between social dominance and milk production under grazing systems. A total of 252 spring calving Friesian x Jersey dairy cows in three groups differing in stocking rate and herd size grazing perennial ryegrass and white clover pasture were observed for three months in early lactation to determine their dominance value. All cows ranged in age from 2 to 11 years and live weight (LW) ranged from 340 kg to 648 kg. Dominance values were determined by social interactions indicating dominance and submission between cows. Social interactions were recorded on a win and loss basis. In all three groups, the dominance value was positively correlated (P<0.05) with age (r = 0.42 to 0.65), live weight (r = 0.33 to 0.47) and milk production (r = 0.32 to 0.42), but no relationship with body condition score was found. In conclusion, older cows with higher live weight were more dominant and tended to have higher milk productio

Can low input dairy systems be economically and environmentally sustainable? Results from a farmlet study

A two-year dairy study was conducted under irrigation at Lincoln, Canterbury, comparing 1. Moderate stocking rate (MSR, 3.9 cows/ha; comparative stocking rate (CSR) of 89 kg live weight (LWT)/t DM (dry matter) offered; 150 kg nitrogen (N) fertiliser/ha/year; grain supplementation of 0.55 t DM/cow/year; wintering cows off- farm); or 2. Low stocking rate (LSR, 2.9 cows/ha; CSR of 91 kg LWT/t DM offered; grazing diverse pasture (Italian ryegrass, plantain, red- and white clover); 103 kg N fertiliser/ha/year; wintering cows on-farm). The Lincoln University Dairy Farm (LUDF; 3.4 cows/ha; CSR of 76 kg LWT/t DM offered; 169 kg N fertiliser/ha/year) was the benchmark. Milk yield, pasture production and quality data were modelled in FARMAX and OverseerFM to estimate financial and environmental performance of each farm. Performance was similar for MSR and LUDF. LSR gave the best environmental outcome across 2018/19 and 2019/20, leaching approximately 31% less N compared with MSR and LUDF. However, annual milk solids per ha were 28% less for LSR relative to MSR and LUDF. Correspondingly, the annual operating profit per ha was 35% less for LSR compared with LUDF. These financial losses can be mitigated in an LSR system if the farmer adopts more complex pasture management

What perennial ryegrass should you sow?

Choosing the right perennial ryegrass or combination of perennial ryegrasses is an important decision to increase the production, persistence and quality of pasture harvested on your farm. Perennial ryegrasses can be effectively classified according to endophyte strain, flowering time and whether a tetraploid or diploid. Endophyte strain should be chosen relative to the known or expected insect pests on your property. Using paddocks of ryegrasses with different flowering dates on your farm will help to improve early and late spring growth and make it easier to sustain high pasture quality and DM intakes throughout spring and into summer. Tetraploid ryegrasses offer high quality feed, easy management and high utilisation but are particularly prone to pugging and treading damage on wet soils in the early part of spring.http://www.side.org.nz/Paper

Development of measurement techniques for use in a nutritive index for ryegrass breeding

Lack of suitable criteria for early screening for nutritive value (NV) of pasture varieties has been indicated as a cause of slow improvement in lamb liveweight gain from new pasture varieties. A study was carried out to develop a NV index that could be used in the early stages of a ryegrass breeding program to rank ryegrass varieties for lamb liveweight gain. A series of four experiments, involving 12 perennial ryegrass varieties (Lolium perenne), differing in flowering date and morphological attributes, were carried out over two autumn seasons (1999 and 2001). Varieties were established in pure sward plots that were mown to a height of 5 cm, two weeks prior to experimental measurements. These swards were used to obtain data for selected NV components (NVCs) that were later used in a multiple linear regression with published lamb liveweight gain data (LWG) to identify appropriate components of a NV index. The same control variety (c.v. Nevis) was used in each experiment so relative values of NVCs could be compared with LWG. Turves of all varieties were dug from established swards and offered in pairs to trained sheep to determine preference, intake rate, bite weight and bite rate. Preference for a variety was determined as the intake of that variety as a proportion (%) of the total intake of both varieties on offer. Representative samples were taken from swards to determine chemical composition; nitrogen (N) and water soluble carbohydrate (WSC) (glkg DM), degradable N to degradable non-N organic matter (g DN/kg DNNOM) in vitro digestibility (IVDMD, glkg DM), force to break leaf (FfB; N/mg DM) and in vitro DM loss after six hours incubation (DML6; glkg DM). Methods for quantifying preference, leaf FfB, DML6 and DN:DNNOM were developed during the study in order to reflect plant resistance to grazing, rumen degradation rate and N to energy balance, respectively. These methods were shown to be precise, repeatable and able to detect significant differences between varieties for preference, leaf FfB, DML6 and DN:DNNOM (50.0 ± 10.8, 4.14 ± 0.17, 529 ± 23, and 3l.6 ± 2.0 respectively) The mean values of a range of NV components (WSC, N, IVDMD, DML6, leaf FfB, DN:DNNOM) were determined by REML analysis for 12 perennial ryegrass varieties for which lamb liveweight gain data was available from published reports. Liveweight gain was used as the dependant variable in multiple linear regressions using different combinations of NV variables as indices of NV. Two of the three indices were significant (P < 0.05) but the backward stepwise" selection resulted in two different indices in terms of the final NV components. It was concluded that neither index provided reliable coefficients because the multiple regression was based on a data set that was limited and the explanatory and response variates were derived from disparate sources. The techniques used for quantifying NVCs were simple to use and required less than 5 g DM sample material, which make them appropriate for screening at early stages of ryegrass selection. Leaf FfB was negatively correlated with intake rate (r = -0.67; P < 0.05) and therefore has potential as an indicator of resistance to grazing, handling time and perhaps even subsequent digestion rate. Sequential in vitro degradation rate (h⁻¹ ) of freeze-dried ground ryegrass was strongly correlated with degradation rate in sacco (r = 0.94; P < 0.05). Selection for ryegrass using dry matter disappearance following a single incubation of six hours in pepsin-cellulase (DML6) may improve rate of rumen degradation and emptying. The ratio between N and energy supply was defined by a DN:DNNOM measurement. A quadratic relationship for DN:DNNOM with lamb liveweight gain was observed, a relationship which supported results in the literature. Significant variation between 12 varieties was recorded for each of the NVCs measured. Previously reported heritability estimates for like-measurements (leaf shear strength, IVDMD and N content) indicate that a response to selection can be expected. It is likely that the NV measurements developed in this research would be suitable for a ryegrassbreeding index. However, it was recommended that the measurements provided in this study initially be used to select the best parent material and that directional selection for improvement of NV is used on subsequent generations. Validation of relative importance of the NV measurements was also recommended following animal performance trials on improved genotypes

Pasture production and botanical composition of high sugar and control ryegrasses with or without endophyte under irrigation in Canterbury

High sugar grasses and novel endophytes are two new technologies promoted for pastoral farmers. While assessing their value for pastoral farming it is important to consider the interactive effects of these technologies on both pasture production and composition. Pasture production and botanical composition was measured over 2 years for a range of perennial ryegrass cultivars infected with different endophyte strains in grazed small plot trials under irrigation in Canterbury. Cultivar and endophyte strain had little effect on total dry matter production; agronomically the UK-bred high sugar grass performed as well as the New Zealand controls. There was a trend for less white clover with ryegrass cultivars infected with AR1 and AR37 endophyte compared with endophyte-free treatments. Generally, endophyte infection is promoted as being beneficial for ryegrasses. However, under irrigated conditions and low levels of insect pressure, the advantage of endophyte infection was minimal.This research was funded by Foundation for Research Science and Technology (Contract C10X0503)

Milk production and urinary nitrogen excretion of dairy cows grazing perennial ryegrass-white clover and pure plantain pastures

Milk production and urinary nitrogen (N) concentration were measured in late lactation dairy cows grazing a perennial ryegrass-white clover pasture, pure plantain and an area that is comprised of 50% perennial ryegrass-white clover and 50% pure plantain by ground area (50-50 pasture-plantain), (n=12). Milksolids production was greater (P=0.01) for cows grazing plantain (1.67 kg MS/cow/d) than those grazing pasture (1.50 kg MS/cow/d), with cows grazing 50-50 pasture-plantain intermediate (1.60 kg MS/cow/d). Urine-N concentration was 56% lower (P<0.001) for plantain (2.4 g N/L) and 33% lower for 50-50 pasture-plantain (3.6 g N/L) than pasture (5.4 g N/L). Plantain may offer environmental benefits to dairy systems by reducing the urinary N concentration deposited on the soil from grazing cows in late lactation

Dietary preference of dairy cows for perennial ryegrass cultivars growing with and without white clover

Dietary preference of dairy cows for eight perennial ryegrass cultivars (AberMagic, Alto, Base, Bealey, Commando, Kamo, One50 and Prospect) growing with and without white clover was examined at two vegetative stages (May and October) and one reproductive stage (November). Groups of dairy cows (n = 8) were offered free choice among cultivars growing with or without white clover for 6 to 8 hours. Preference was defined as the relative decreasing rate in sward surface height. Preference was higher for the tetraploid cultivars, Base and Bealey and the high-sugar diploid cultivar, AberMagic (preference ranged from 1.02 to 1.45). Preference was negatively correlated with herbage mass (r = -0.179, P = 0.013), proportion of dead material (r = -0.301, P < 0.001) and neutral detergent fibre (r = -0.287, P < 0.001), and positively correlated with sward surface height (r = 0.386, P < 0.001), ryegrass lamina length (r = 0.233, P = 0.001), tiller mass (r = 0.338, P < 0.001), water-soluble carbohydrate concentration (r = 0.143, P = 0.049) and organic matter digestibility in dry matter (r = 0.312, P < 0.001). Although the proportion of white clover was low (< 7% DM) in all three experiments, the interactions between perennial ryegrass cultivar and the presence of white clover were significant (P = 0.004 at pre-heading stage, P = 0.046 at reproductive stage and P = 0.038 at post-heading stage), with differences among preference for perennial ryegrass cultivars reduced when white clover was presen