Feeding maize silage in winter: Setting the herd up for success
As I write this article, we have just had our first frost in the Waikato, a change in weather signalling that winter is upon us.
Livestock Improvement Corporation (LIC) has been working to investigate how slickcoated cows – cows bred with the ‘slick’ variation – fare in colder climates.
Cows typically experience heat stress on days 22°C with 75% humidity, something LIC says is a concern because NIWA predicts that by the end of the century, the frequency of ‘hot days’ with maximum temperatures exceeding 25°C will double under modest modelling scenarios.
LIC chief scientist Richard Spelman says the slick variation was discovered approximately a decade ago in Senepol, a Caribbean beef bred, and since then LIC has been cross-breeding Senepol cows with New Zealand dairy cattle.
“Where we’ve got to now is that we have animals on the ground which only have about 3% of the Senepol breed still in them and they also have the slick variation. The other 97% is elite New Zealand dairy genetics,” says Spelman.
The programme has found that cows with the slick variation have lower rumen temperatures (0.5- 1.0°C) when compared with non-slick cows under certain temperature and humidity conditions.
Spelman says that the major question that has been asked is whether the heat tolerant cows are more cold sensitive.
Subsequently, LIC has worked with both Lincoln University and Massey University to test that cold sensitivity.
“It wasn’t a very controlled setting,” Spelman says of the initial trial.
“You were really dependent on whether you’ve got a cold day so you couldn’t really control it at all.”
The solution that was found to this issue which was used in the trials performed this year was to use a refrigerated shipping container that has been modified and then the temperature can be changed.
The result of the trial was that both control animals (cows without the slick variation) and the slick animals reacted the same to the cold temperatures.
“We’re really pleased to see that they [the slick cows] aren’t more sensitive to the cold which is an important one for us as we continue to invest quite heavily into the breeding programme so these animals will be robust under cold conditions and better under warm conditions,” Spelman explains.
Spelman says that overall LIC’s research into the slick variation could have a positive impact for the industry.
“A lot of the information that we have for the future is around the forecast of increased dry or hot days through summer,” he says.
“So, if we take those assumptions, we’ll have more hot days, these animals won’t be affected by the heat so the animal welfare of the animals will be better,” Spelman explains. “The expectation is that they will continue to eat and potentially produce more milk through that hot period as well because they won’t be affected quite as much.”
Spelman says the next step for the programme is to undertake a round of mating this spring and if progress continues as planned, Kiwi farmers will be able to breed heat tolerant cows by 2029.
