The Dairy Council for Northern Ireland, in conjunction with the European Milk Forum, recently hosted a webinar highlighting the impact of reduced protein levels in diets offered to freshly calved cows.
The event took the form of a virtual farm visit, hosted by Drew and Valerie McConnell. The couple farm on the outskirts of Omagh in Co. Tyrone. They had previously taken part in an Agri-Food and Biosciences Institute (AFBI) trial, investigating the role of protein in dairy cow diets.
Drew and Valerie McConnell Image source: Dairy Council NI
Drew and Valerie milk 160 Holstein cows. Current 305-day yields are in the region of 10,000L. The top 60 yielders are milked courtesy of a robot with the remainder of the herd put through a conventional parlour twice daily.
“We target 3,000L from grass and silage annually. In a dry year, it has been possible to get this figure up to 4,000L,” Drew explained.
“We believe that improving efficiency across every aspect of the farm is the only way to secure a sustainable future for ourselves.
“The Holstein cow works for us in this regard. Using new, high-energy grass varieties is another driver for the business, as is making best use of slurry.
All our slurry is spread using a dribble bar. This approach maximises the fertiliser of the slurry while also reducing the amount of ammonia gas that escapes to the atmosphere.
Soil testing
The McConnells reseed all their swards every seven years. They will add lime at that stage. However, the entire farm is soil tested every three years.
“The results of the soil test dictate our entire fertiliser management programmes. Fields found to have depressed pH value will be limed accordingly. There is sufficient potash in the slurry to meet our production needs with additional phosphate applied, as required,” Drew added.
“Taking this approach has allowed us to reduce our chemical fertiliser usage dramatically over the past number of years.”
AFBI trial
The AFBI trial carried out on the McConnell farm was designed to assess the impact of feeding concentrates containing reduced protein levels on freshly calved cows. The parameters measured courtesy of the work were: body condition score, subsequent fertility and 305-day yields.
However, this approach did impact beneficially on subsequent fertility while also helping to maintain body condition scores immediately post-calving. The reduced protein rations had been fully rebalanced from a metabolisable energy perspective.
“Our own trial fully confirmed the results of the original research. The work also focused on the benefits of calving heifers down at 24 months of age,” Drew continued.
“This approach works from a number of perspectives. In the first instance, it reduces the carbon footprint across the farm as a whole.
This is a direct consequence of having to keep less cattle within the business. In turn, this increases the amount of land that we can dedicate to actually producing milk.
“It requires a fundamental change of mindset to have heifers calving down at 24 months. For example, inseminating animals at just 13 months of age takes a bit of getting used to.
“But it is an approach to management that works. We have found that calving at 24 months of age actually increases cows’ longevity within the herd.
Milk production
“We now have a number of animals that have produced over 100t of milk. Most cows will stay within the milking group for at least five lactations,” Drew said.
“As a consequence, our herd replacement rate is now down at 16%.”
“Reducing dietary protein levels encourages cows to milk on for longer periods of time,” Drew said.
“In any event, we are not in that big of a hurry to get cows back in calf. However, I do use a lot of sexed semen on the cows. This is expensive, so it is important to maximise conception rates.”