Short-season high-moisture corn products in western Canadian beef cattle diets

As low-heat unit corn becomes more abundant in western Canada, alternative utilization methods to corn silage and standing corn for grazing should be investigated. The objectives of this dissertation were to 1) evaluate yield and production costs of low-heat unit, high-moisture shelled corn (HSC) and snaplage; 2) evaluate the potential to utilize low-heat unit, HSC stover in a winter grazing system for pregnant beef cows relative to grazing whole-plant barley in a swath grazing system including system economic costs; 3) characterize low-heat unit HSC stover quality based on each plant component at the appropriate time of harvest and the digestibility of each component; and 4) evaluate the use of low-heat unit, high-moisture corn products (HSC and snaplage) in finishing diets compared to barley grain and silage. Over two consecutive years, high-moisture corn products (HSC, snaplage, and HSC stover) and barley greenfeed (BAR) were produced at the Livestock and Forage Centre of Excellence (LFCE; Clavet, SK, Canada). These products were utilized in five experiments: two in vivo winter feeding studies examining the use of HSC stover compared to BAR as forage for dry pregnant beef cows; one in vitro batch culture study comparing the nutrient composition and disappearance of anatomical components of HSC stover and BAR; one in vivo, metabolism study comparing the previously mentioned diets in site and extent of nutrient digestibility; and one in vivo small pen study comparing performance of steers finished on a traditional barley-based diet and those that substituted barley products with high-moisture corn products. An economic summary based on the results of these studies and crop production data was prepared. Both HSC and snaplage, along with their stovers, yielded less dry matter (DM) than BAR in 2020, but HSC and its stover yielded more DM than BAR in 2021. Production costs ($/ha) were greatest for snaplage, then HSC, then BAR. When HSC stover was swathed, cows performed similarly to those fed swathed BAR, but BAR was more economically favorable. When baled, cows fed BAR had greater final body weights (BW) and body condition scores (BCS), but HSC stover was more economically favorable. In vitro batch culture revealed that BAR leaves had the highest forage quality based on nutritional composition and in vitro fiber disappearance, while HSC stover cobs had the lowest forage quality. In the metabolism study, the barley grain finishing diet was comparable in starch digestion and live performance to a diet substituting 50% of barley grain with HSC (DM basis), but the diet containing HSC yielded heavier carcasses in the performance study. Additionally, when barley silage and approximately 10% of barley grain were replaced with snaplage, there were no differences in live performance of finishing steers, but ruminal starch digestion was more complete in the metabolism study, although severe liver abscesses were less common in the performance study. Substituting snaplage in finishing diets produced lower costs of gain than buying all feeding ingredients, and substituting HSC was more expensive than the traditional barley finishing diet. These results indicate that short-season high-moisture products are acceptable replacements for barley products in western Canadian beef cattle diets, but HSC was not as economically favorable at the time of the current study