Producers need to keep energy needs and other nutritional requirements in mind when using alternate feed ingredients
By Jackie Clark
Corn rootworm has become a prevalent pest in Ontario, which may require growers to replace corn acres with other crops. This shift may, in turn, necessitate some changes to livestock diets.
Dr. Denise Beaulieu gave producers some background knowledge about replacing corn with wheat in pig diets at the virtual London Swine Conference. Beaulieu is an assistant professor at University of Saskatchewan
Her goal was to help farmers “gain confidence in utilizing alternate ingredients, especially wheat, in swine rations,” she explained.
Soft red winter wheat is the most common type grown in Ontario. Beaulieu explained some of the differences between feed wheat and Eastern Soft Red Winter No. 1.
“Feed wheat can be any variety except durum,” she said. “Importantly, the percentage of ergot and mycotoxins can vary considerably. Ergot can be 0.1 per cent in feed wheat, compared to 0.04 per cent in No. 1.”
Sclerotinia, which is evidence of ergot contamination 0.25 per cent compared to 0.04 per cent, she added. Fusarium damage can be five per cent in feed wheat compared to one per cent. Also, feed wheat can contain up to 10 per cent foreign material compared to 0.8 per cent for No. 1 grade.
“2.5 per cent can be heated or mouldy, no limit on shrunken kernels, 50 per cent of kernels can be broke, and no limit on sprouted kernels” for feed wheat, she explains. “I’m not saying that we shouldn’t be using feed wheat, but we have to be aware of some of the differences … and it should be priced accordingly.”
In pig feed, “we’ll also be able to use some of the co products from wheat milling,” Beaulieu said. Those products can be called different names and have a range of crude fiber values.
Farmers “want to have some way, when we’re buying this wheat, to estimate feed quality, and the easiest, of course, would be bushel weight,” Beaulieu said.
Recent research indicated that feed efficiency is reduced using low bushel weight wheat, because daily gains are lower with the same feed intake, she explained.
“This is primarily due to a decrease in the energy content of this wheat,” she said. “However, in the discussion, the authors note that the low (bushel weight) wheat had reduced content of gross energy, it also had low crude protein and lysine content. And, this is important, it also had higher levels of mycotoxin. So, it’s really difficult to determine if these differences are due to mycotoxin contamination, or differences in density, or both.”
The scientists conclude that bushel weight “combined with chemical and mycotoxin analysis can be used as a predictor of wheat quality,” she added.
Older research from Saskatchewan showed that xylose (a type of sugar) content was correlated with digestible energy (DE), whereas bushel weight, or density, was not.
“Density is not really a good predictor of energy content but it can certainly be used as an indication of other potential quality factors, so it’s one thing we can have in our toolbox,” Beaulieu said.
OMAFRA recommendations suggest that producers can feed up to 95 per cent wheat to grow-finish pigs and 90 per cent during gestations, but only 40 per cent during lactation.
“You want lower levels during lactation because lactation diets require a higher energy content,” Beaulieu explained. “The energy content of wheat is less than corn … however wheat is higher in crude protein, specifically it’s higher in lysine which is typically the first limiting amino acid in our diets.”
She also outlined data informing decisions around processing and particle size, using enzymes like carbohydrase, and the impact of wheat in the diet on pork carcass quality.
Reducing particle size in meal diets can improve average daily gains and feed efficiency, in pelleted diets there was no difference, she explained.
Potential exists “for carbohydrases to improve the digestibility of wheat-based diets. An improvement in digestibility has not always been accompanied by an improvement in performance, and the effect of these carbohydrases is inconsistent,” she added. “We probably need some additional research in this area.”
Finally, “fatty acid composition varies dramatically between corn and wheat,” she explained. “We could expect that substituting fat for corn would give us a fat that is harder and perhaps whiter, the consumer might notice a difference in fat quality, especially if they’re used to corn fed pigs.”
However, when investigated in 2005, there was no effect of diet on carcass characteristics, pork fat composition, or colour.
One key takeaway was to remember “when we are using alternative ingredients … it’s even more important that we use the net energy system. We need to be able to put an accurate valuation of the energy content of the diets,” said Beaulieu.
“Similarly, we should be using standardized ileal digestible amino acids, not total amino acids, and standardized total tract digestible or available phosphorus,” she added.
Zoran Rakic\iStock\Getty Images Plus photo