Dry Matter Intake, Milk Performance and Production Efficiency from Spring Calving Dairy Cows Offered Grass-Only, Grass-White Clover and Total Mixed Ration Diets

In pasture-based dairy production systems, dry matter intake (DMI) is one of the main factors curtailing milk production and production efficiency. The inclusion of white clover (Trifolium repens L.) in swards of perennial ryegrass (PRG; Lolium perenne L.) can increase DMI from increased sward nutritive value over a grass-only sward. Feeding a fully balanced TMR diet can enhance milk production as a result of greater DMI and through greater control of feed quality. Therefore, the objective of this study was to determine the relationship between DMI, milk production, and energy efficiencies for dairy cows consuming different diets. A farm systems experiment was conducted from 2015-2021. The three treatments were: TMR (100% confinement; grass silage, maize silage, concentrate), grass-only herbage (GR), or grass-white clover herbage (CL). Dry matter intake was estimated 17 times over the duration of the study, using the n-alkane technique for the GR and CL treatments, and an electronic roughage intake control system for the TMR treatment. Simultaneously, milk production, and production efficiencies were also measured. Significant increases (P \u3c 0.001) in milk production, DMI, and production efficiencies were observed when cows consumed the TMR diet compared with the grazing diets. Greater energy (P \u3c 0.001) was available for milk production after maintenance for the TMR treatment. All treatments had similar energy (148.64 g Unité fourragère lait; UFL) available for milk solids (MS) production after accounting for maintenance. Cows consuming the TMR diet had significantly higher (P \u3c 0.001) daily energy intake (+17%) compared to the pasture-fed cows. Cows grazing the CL swards consumed 1.03 kg greater (P \u3c 0.001) total DMI compared to the GR cows. This translated into greater daily milk (+1.2 kg) and MS (0.12 kg) compared with the GR treatment. The current study highlights the benefits of a TMR and ryegrass/white clover diet for increasing milk production, and energy efficiencies above a grass-only diet

Dry Matter Yield of Perennial Ryegrass Cultivars under Mechanical Cutting and Animal Grazing

Perennial ryegrass evaluation trials are essential to identifying and promoting the most productive cultivars for use at farm level to maximise sward productivity (Grogan and Gilliland 2011). Cultivar testing is predominantly conducted under simulated grazing trials to predict dry matter yield (DMY) performance under animal grazing. Previous studies have shown a high correlation in DMY between these two defoliation methods (Camlin and Stewart 1975; Creighton et al. 2010). In contrast, Binnie and Chestnutt (1991) demonstrated that swards grazed by animals had higher DMY performance than those exposed to simulated grazing managements. Animal pressures such as pulling, treading and nutrient return are not present in a simulated grazing management. The objective of this study was to determine if a relationship exists between the DMY of perennial ryegrass cultivars exposed to mechanical cutting compared to animal grazing

A Retrospective Analysis of White Clover ( Trifolium repens L.) Content Fluctuation in Perennial Ryegrass ( Lolium perenne L.) Swards under 4 Years of Intensive Rotational Dairy Grazing

International audienceThe objective of this study was to examine fluctuations in white clover (Trifolium repens L.) content in perennial ryegrass (Lolium perenne L.) swards within a high nitrogen (250 kg N/ha) input grazing dairy system. The data came from a larger, overall system experiment within which all management and growing condition variables were categorised each year for the 40 paddocks that contained perennial ryegrass-white clover swards, over four growing years. Within that study, eight perennial ryegrass cultivars were examined, each sown individually with two white clover cultivars in a 50:50 mix of ‘Chieftain’ and ‘Crusader’. To determine management associations and meteorological patterns with white clover content and rate/direction of change, separate generalised linear models were used to analyse each individual management or meteorological variable. Paddocks with high white clover contents were associated with lower pre- and post-grazing sward heights, lower pasture cover over the winter period and shorter over-winter period. Perennial ryegrass cultivars with lower pre- and post-grazing height, lower pre-grazing pasture mass and pasture yield removed, all retained more white clover in their swards. Soil fertility remained a key factor that affected white clover persistence influencing the degree of responses in all treatments, particularly soil phosphorus (P) levels. Beyond this, higher white clover contents and lower rates of white clover decline were associated with paddocks that received lower rainfall, had higher soil moisture deficits and received more radiation into the base of the sward, particularly around the time of grazing