Starling proofing could be well worth the investment on some farms, following new research findings which equated the negative effect of the birds on ration composition to around £40,000 per winter.
As part of a Nottingham University dissertation with dairy scientist Professor Phil Garnsworthy, Kerensa Hawkey monitored the effects of starlings on 10 farms in Cornwall and North Devon in the winter of 2015. The farms were all Mole Valley Farmers customers, with all silage testing carried out through the farmer owned business.
Herd size varied from 200 to 1,000 cows with all herds fed a TMR. Maize and grass silage were the main forage elements on all farms, apart from one, where wholecrop was fed. Building design and feeding varied between farms with some feeding inside and other feeding in troughs outside.
The amount of feed stolen by starlings was assessed by comparing weight and compositional changes of TMR samples either exposed to the birds or covered to prevent stealing.
• Starlings ate 18-43% of ration samples, highlighting that they could be removing nearly half of the diet on a daily basis.
• There was a significant decrease in feed components of <4mm, suggesting starlings were picking out the cereal and protein components.
• There was a 14% reduction in dry matter concentration from morning to evening, equating to a 7.5 litre reduction in yield per cow per day.
• Weather conditions and building design did not affect the number of starlings or feed loss - it was more a case of location of the farm in relation to roosting places.
The loss in energy and protein alone equated to a cost of £0.97/cow/day - a figure that correlates with AHDB Dairy research findings from 2012 which suggested a £0.96/cow/day loss (However this included loss in milk output as well).
The cost figures calculated were based on data from one of the trial farms, which was one of the worst affected by the starlings. However, the fact last year was a mild winter and starling numbers were lower than in some years suggests the figures could be a conservative estimate.
Mole Valley Farmers nutritionist, Dr Robin Hawkey says the trial results have huge implications on ration formulation.
“Usually we say there are four rations; what is formulated, what is mixed, what is fed out and what the cow’s eat, but maybe we need to reassess and think of the five rations. We could say there’s two sets of sorting; the cows and the starlings,” he says.
The removal of the “goodies” in the ration and reduction in energy density not only has ramifications in terms of yields, but also to fresh cow health, potentially leading to higher levels of ketosis if left unaddressed.
The trial also clearly showed the benefits of starling proofing buildings. Mark Button from Polshea Farm in St Tudy, was the only farmer to have carried out such work at a cost of around £5,000 for materials plus £10,000 of labour.
By doing so, the number of starlings present was reduced, but not eliminated leading to a saving of 0.15kg/cow/day in lost feed value on his 940 cow herd.
Miss Hawkey, who is now trainee feed formulator for Mole Valley Farmers says: “This 0.15kg/cow/day is equal to 25,380kg for 940 cows over a 180 day starling season. In terms of milk yield, that’s 55,836 litres or around £11,000. So by improving buildings, farmers could save around £11,000 a year or even more if starling incidence is higher.”
Dr Robin Hawkey says the huge financial impact of starling infestations highlights how farmers could benefit from standing back and assessing the scale of the issue on their farm. This is also vital considering the potential impact of starlings on cow health due to the transmission of diseases, such as E.coli and salmonella.
“If there’s a starling problem on your farm, go out and assess the TMR and evaluate how much of an issue you’ve got. Take a sample of the TMR at feed out and in the afternoon and send it for analysis and put it through a Penn State separator to assess the change in particle size,” he explains. An informed decision can then be made as to whether investing in starling proofing is worthwhile.