As animal genetics and feeding practices change, producers must also adjust feed to ensure nutritional requirements are met
Livestock producers can’t rely on the same old science when formulating rations.
That’s because they’re not feeding the same old animals the same old way, researchers and experts told animal nutritionists and farmers at the Western Nutrition Conference Sept.30.
“If we’re going to be doing some genetic selection with (residual feed intake) and selecting for cattle that are more efficient, we know we won’t have the same cow in the year 2020 that we had in 1990,” said Alberta Agriculture livestock research scientist Susan Markus.
“Maybe our nutrition and our formulating need to change to take account of that.”
Mark Engstrom of feed company DSM highlighted the changing nature of dairy production, saying different cow treatment means farmers can’t just “set it and forget it” with feed, especially if farming practices change.
Modern dairy cows are often vitamin A deficient, a result of low beta-carotene in modern dairy diets.
“I think it’s just that our feeding practices have changed,” said Engstrom.
He said dairy cows once spent a lot of time on pasture, eating green chop and alfalfa haylage, but now many of them spend most of their time indoors eating corn silage. That means the beta-carotene sources are much fewer than in the past, but many farmers don’t realize that.
“We have corn silage. We have dried hay, and so our ration sources are lower for (beta-carotene).”
Markus highlighted the significant difference in body shape and physical composition of cattle from the 1950s to 1990s. The same applies to pigs, which once were much fattier and less muscled.
The change in physical composition might bring different dietary needs.
“The animal is changing physically.… We have changed the type of animal. If now we select for feed efficiency, maybe we need to take a closer look at nutrition, and it may change the way you formulate,” said Markus.
“Maybe that means our nutritional requirements need to change for the animals. We can’t just keep doing the same things we have done.”
The science that underlies feeding recommendations might also need to be revised, said Jeff Firkins of Ohio State University.
Livestock research from decades ago might not be a good source of understanding for animals that are now profoundly different.
“I’ve never been one to just take dogma,” said Firkins.
“I always challenge it. Sometimes I end up agreeing with it. (But) we should never just accept it. You need to go find out for yourself the origin, go look at the original papers and then figure out what you think.”