Effect of perennial ryegrass (Lolium perenne L.) cultivars on the milk yield of grazing dairy cows

Abstract

The objective of this experiment was to investigate the effect of four perennial ryegrass cultivars: Bealey, Astonenergy, Spelga and AberMagic on the milk yield and milk composition of grazing dairy cows. Two 4 3 4 latin square experiments were completed, one during the reproductive and the other during the vegetative growth phase of the cultivars. Thirty-two Holstein-Friesian dairy cows were divided into four groups, with each group assigned 17 days on each cultivar during both experiments. Within each observation period, milk yield and milk composition, sward morphology and pasture chemical composition were measured. During the reproductive growth phase, organic matter digestibility (OMD) was greater for Bealey and Astonenergy (P , 0.001; 11.6%). AberMagic contained a higher stem proportion (P , 0.01; 10.06) and a longer sheath height (P , 0.001; 11.9 cm). Consequently, cows grazing AberMagic recorded a lower milk yield (P , 0.001; 21.5 kg/day) and a lower milk solids yield (P , 0.001; 20.13 kg/day). During the vegetative growth phase, OMD was greater (P , 0.001; 11.1%) for Bealey, whereas the differences between the cultivars in terms of sward structure were smaller and did not appear to influence animal performance. As a result, cows grazing Bealey recorded a higher milk yield (P , 0.001; 10.9 kg/day) and a higher milk solids yield (P , 0.01; 10.08 kg/day). It was concluded that grass cultivar did influence milk yield due to variations in sward structure and chemical composition.Keywords: perennial ryegrass, cultivar, sward structure, dairy cow, grazing ImplicationsThis study investigated the effect of four perennial ryegrass cultivars on dairy cow milk yield and identified the cultivar characteristics responsible for variations in milk yield. The information generated by this study will be of significant use in pasture-based production systems. As the study identified the cultivar characteristics responsible for animal performance, it will allow grass breeders to increase their focus on such traits. Animal performance-orientated breeding programmes should result in grass cultivars becoming available to farmers that will increase animal performance from grazed grass, thereby further improving the economics of pastoral-based animal production systems.

Comparison of perennial ryegrass,Lolium perenneL., ploidy and white clover,Trifolium repensL., inclusion for herbage production, utilization and nutritive value

“…Tetraploid swards had lower NDF and DM contents when compared with diploid swards, which is similar to Wims et al. (), and Smith et al. (), and this is due to an increased ratio of cell contents to cell walls.…”

“…Tetraploid swards maintained superior herbage nutritive value than diploid swards throughout the grazing season due to lower postgrazing sward height, similar to O'Riordan, O'Kiely, and Keane () and Wims et al. (). Tetraploid swards had higher herbage OMD levels than diploid swards.…”

“…This was despite the diploid swards maintaining a consistently greater tiller density than tetraploid swards as well as a higher sward bulk density. Given that there was also a higher postgrazing sward height, the indication was that the dairy cows found it more difficult to graze to the bottom of diploid swards (Wims, McEvoy, Delaby, Boland, & O'Donovan, ).…”

Using Ecophysiology to Improve Farm Efficiency: Application in Temperate Dairy Grazing Systems

“…Early inroads are being made into this field. For example, Wims et al [71] identified an important interaction between cultivar and growth stage (vegetative versus reproductive) which influenced relative milk production of dairy cows and concluded that sward structural differences between cultivars are more important during reproductive development, while differences in digestibility are more important during vegetative growth. There is more to be learnt in this field of plant phenotypic variation and pasture-animal interactions, which offers gains for pasture-based livestock producers in all temperate regions.…”

Effects of predicted milk yields sustained by grazed grass on dairy cow performance and concentrate requirements throughout the grazing season

“…As a consequence of their greater nutrient demands, managing these higher‐yielding cows during the grazing period provides a considerable challenge. For example, while grazed grass as the sole feed may be able to sustain the milk yields of low‐ and medium‐yielding cows (Thomson et al ., ; Bryant et al ., ; Chapman et al ., ; O'Neill et al ., ; Wims et al ., ), it cannot meet the energy requirements for milk production of high‐yielding cows (Kolver and Muller, ). As a result, there has been an increase in the amount of concentrate feed offered to these cows, and a consequential decrease in the proportion of total milk sustained by grazed grass in many of the grassland‐based systems in which these cows predominate.…”