UCD Lyons Research Farm Update

The development of a high output grass-based spring milk production system

Zoe McKay2, Finbar Mulligan1, Karina Pierce2, Bridget Lynch2, Ciaran McDonnell2, Nicholas Ryan2, Niall Walsh1,2, Alan Fahey2, Michael Wallace2
1School of Veterinary Medicine, University College Dublin, Ireland.
2School of Agriculture and Food Science, University College Dublin, Ireland.

Background

In regions where it is possible to grow and graze large quantities of highly digestible perennial rye grass it is favourable to produce as much milk as possible from this low-cost feed source.  However, dairy production systems that have been developed to utilise large quantities of grazed grass have mostly been based on low-output per cow.  With these low-output systems, high levels of profitability are possible through avid cost control and comparatively high stocking rates.

There are now many reasons to consider the development of grazing systems that are based on high-output per cow. These reasons include

concerns about increasing dairy cow numbers and environmental emissions
facilitating farm expansion post EU-milk quota removal for land limited and fragmented farms
increased requirement for dairy product for export
lack of available skilled labour and infrastructure at farm level to deal with expanding animal numbers
concern over the continued allowance of high-stocking rate systems within the EU nitrates directive derogation.

Given the significant costs associated with farm expansion and the fact that many farmers are operating on a land-bank that is limiting the expansion of their business, higher output spring calving grazing systems may offer an opportunity to grow the dairy business. Such a system might facilitate the successful expansion of the farm business without the need to buy or rent extra land, to buy stock, to acquire extra labour or to provide extra cow facilities.

The focus in such a system is on maximising milk/milk solids output from the existing land holding which involves high output from individual cows. This will occur most efficiently through maximising the use of grazed grass/home grown forage in the system and the strategic use of supplementation thereafter. At a national level, the adaption of such a system would allow for the continued expansion of the Irish dairy industry without the need to increase dairy cow numbers by as much as what a low output system would require.

In this ongoing study, the animal and grassland performance for a grazing system based on high-output per cow and the resultant dairy production system profitability will be reported.  The project began in 2016 and data has been collected for four full production years. To date, the system has been profitable, achievable and sustainable.

Project objectives

To develop a profitable high output grass-based spring milk production system
To incorporate the most recent advances in grassland management for dairy farms into a high output system
Use a type of dairy cow that has good genetic indices for both milk production and fertility
Employ the best practices from nutrition research and dairy cow husbandry
Incorporate nutritional studies into a high output system
To incorporate management technologies and system attributes that enhance the environmental sustainability of dairy production

Targets of the system and milk production results to date

The herd of 60 cows are in the top 1% of herds nationally with an EBI of €206, a milk sub-index of €69 and a fertility sub-index of €87 (January 2020, evaluation). The performance target is 625kg of milk solids per cow per lactation with a target stocking rate on the milking platform of 3.4 LU/ha and a whole farm stocking rate of 2.4 LU/ha. The performance target is approximately 46% higher than the national average figure of approximately 427kg of milk solids per cow.

Fertility targets are ambitious for a high output herd and are the same as those used to benchmark for lower output high fertility herds (75% 6-week in calf rate for the milking herd).

To date, output per cow is within 5% of the target set, with 586kg milk solids produced in 2019 resulting in just under 1,400kg milk solids per ha on the whole farm. The latest 305d predicted data (as of the 4th October 2020) indicates that the target yields for milk kg and milk solids kg may be achieved this year.

From a feeding perspective, the focus is to maximise grass intake with approximately 75% of the diet coming from grazed grass and grass silage (DM basis). On an as fed basis, the annual feed budget consists of approximately 94% grazed grass and grass silage. However, achieving over 600kgs milk solids will not happen with grass only and therefore cows are fed 1,500kgs concentrates over the lactation to meet energy requirements. Cows are fed a flat rate as in the table below with high feeding rates for the first 4 months post-calving and high overall intakes are achieved.

Within this study we have taken a further step to investigate nutritional methods that may increase the environmental sustainability of the system which is one of the main challenges facing the dairy industry. Supplementary feeding of dairy cows at grass offers an opportunity to explore this.

In 2019 we investigated the usefulness of a low crude protein concentrate supplements (14% versus 18%) from April through to September to reduce nitrogen emissions lost to the environment. Building from this work, in 2020 we used a low protein native feed ingredient concentrate with the objective of reducing the carbon footprint of the system by reducing the reliance on imported feed ingredients. The herd was split into three groups and were offered a 14% protein concentrate, 12% protein native formulation concentrate or a 12% protein non-native concentrate in the parlour for the main grazing season (6th April – 9th October).

2016 2017 2018 2019 2020
Number of cows bred 58 (of 58) 59 (of 60) 55 (of 60) 56 (of 58) 54 (of 57)
Submission rate % 91 90 96 95 91
First service conception rate % 43 49 69 64 74
6-week in-calf rate % 59 54 83 79 87
Empty rate of total cows % 9 15* 13* 12* 9*

*Figure includes cows not selected for breeding

Fertility

The breeding season totaled 10 weeks in 2020; it commenced on 2nd of May. The twenty-one-day submission rate was 91% with a 1st service conception rate of 74%. Six week in-calf rate was a very respectable 87%. The overall empty rate, including cows not selected for breeding, was 9%. High levels of fertility are currently being achieved with a group of cows that are within the top 5% of herds for fertility subindex.

Fertility performance of UCD high output grazing herd
Days in milk 0-20 21-60 61-90 91-120 121-180 181-240 241-270 271-305 306-365 Total annual DMI
Silage DMI 5 0 0 0 0 0 5 15 8.5 1.3 t DM
Grass DMI 10 15 15 15 15 14 7.5 0 – 3.5 t DM
Concentrate 8 8 7.5 6 3.5 3 3 3 – 1.5 t fresh

Grassland

This system has a very strong focus on growing and utilising as much grass as possible. In 2019 the milking platform grew 14.5 t DM/ha, with 9.6 grazings achieved on average per paddock with cows at grass for 263 days. Grazed grass utilized equated to 11.6 tonnes of DM/ha in 2019, and overall utilisation was 93% (13.5 t DM/ha). Despite a drought period in May and June, 12.6 t DM/ha of grass was grown up to 4th October in 2020 with approximately 13.5 t DM/ha expected to be the year’s annual total.

As grass is the corner stone of this system, we continue to aim to maximise grazed grass intake throughout the year with the autumn period being a great importance in order to achieve this.

Findings to date

High levels of milk and milk solids output per cow and per ha are achievable from moderate concentrate feed input in a grazing system.  These high levels of output are possible from cows that score highly on a selection index that has had a significant fertility component for some time. High levels of grass utilisation can also be achieved in higher output grazing systems. The system has also been found to deliver good levels of profitability. The system currently has a favourable comparative life cycle analysis for estimation of carbon footprint.